US20110049245A1

US20110049245A1 - Optical reader having reduced specular reflection read failures

Info

Publication number: US20110049245A1
Application number: US12/853,090
Authority: US
Inventors: Ynjiun P. Wang
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-03
Filing date: 2010-08-09
Publication date: 2011-03-03
Anticipated expiration: 2026-06-02
Also published as: US12001913B2; US20230147821A1; US20180365461A1; US10949634B2; US9058527B2; US20230105536A1; US20210192161A1; US20230088760A1; US11625550B2; US20230090343A1; US20220284204A1; US20230109181A1; US20060283952A1; US12026580B2; US20230214612A1; US20230252252A1; US8196839B2; US11238251B2; US7770799B2; US9454686B2

Abstract

There is provided in one embodiment an optical reader having an image sensor array. In one embodiment, the image sensor array can include a first subset of pixels and a second subset of pixels. The first subset of pixels can be devoid of light polarizing filter elements, and the second subset of pixels can be light polarizing pixels including light polarizing filter elements. An optical reader can be configured to selectively read out image data from an image sensor array's light polarizing pixels.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 11/445,930 filed Jun. 2, 2006 entitled, “Optical Reader Having Reduced Specular Reflection Read Failures” which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 60,687,606, filed Jun. 3, 2005 and titled “Digital Picture Taking Optical Reader Having Hybrid Monochrome And Color Image Sensor Array,” (now expired) and to U.S. Provisional Patent Application No. 60/690,268, filed Jun. 14, 2005 and titled “Digital Picture Taking Optical Reader Having Hybrid Monochrome And Color Image Sensor Array,” (now expired) and to U.S. Provisional Patent Application No. 60/692,890 filed Jun. 22, 2005, entitled “Digital Picture Taking Optical Reader Having Hybrid Monochrome And Color Image Sensor Array” (now expired) and to U.S. Provisional Patent Application No. 60/694,371 filed Jun. 27, 2005 entitled “Digital Picture Taking Optical Reader Having Hybrid Monochrome And Color Image Sensor Array” (now expired). The referenced U.S. patent application Ser. No. 11/445,930 and all of the aforementioned provisional patent applications are herein incorporated by reference in their entirety. The aforementioned U.S. patent application Ser. No. 11/445,930 is also related to U.S. patent application Ser. No. 11/174,447 filed Jun. 30, 2005 entitled, “Digital Picture Taking Optical Reader Having Hybrid Monochrome And Color Image Sensor” (now U.S. Patent Publication No. 2006/0274171) which is also incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to optical readers in general and specifically, to an optical reader having a reduced specular reflection read failures.

BACKGROUND OF THE PRIOR ART

Performance of an optical reader may be hindered where an optical reader is operated to read bar code symbols or other indicia of a substrate having a “shiny” surface. Such substrates can include, e.g., metal, glass, and laminated plastic. Light rays emanating from a reader that are projected on a highly reflective shiny surface of a substrate may be substantially entirely reflected directly onto a reader image sensor array. Artisans skilled in the art of optical readers regard a “specular reflection” read condition to have occurred where a substantial percentage of light rays are reflected from a substrate and directed onto a reader image sensor array. Light rays are said to be reflected at a “specular” angle when light rays are reflected from a substrate at about the angle of incidence. Specular reflection tends to saturate a reader image sensor array to cause decoding failures.
There is a need for an optical reader configured so that specular reflection read errors are reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention can be better understood with reference to the drawings described below, and the claims.

FIG. 1 a is an electrical block diagram of a hand held optical reader of the invention including a hybrid monochrome and a color sensing solid state image sensor array;

FIG. 1 b is a block diagram of an alternative image sensor array which may be incorporated into an optical reader according to the invention;

FIG. 1 c is a schematic block diagram illustrating an RF communications circuit according to the invention;

FIG. 1 d is a schematic block diagram illustrating a display according to the invention;

FIG. 1 e is a schematic view illustrating incorporation of a decode circuit, a signature autodiscrimination circuit, a demosaicing circuit, and a fusion circuit into an optical reader according to the invention;

FIGS. 2 a-2 d are various partial exploded top views of an embodiment of a solid state image sensor array according to the invention;

FIG. 3 a is a cutaway exploded side view of a monochrome pixel according to one embodiment of the invention;

FIG. 3 b is a top view of the pixel shown in FIG. 3 a;

FIG. 3 c is a cutaway exploded side view of a color sensitive pixel in one embodiment of the invention;

FIG. 3 d is a top view of the pixel shown in FIG. 3 c;

FIG. 4 a is an electrical block diagram of an embodiment of an image sensor according to the invention;

FIG. 4 b is an electrical block diagram of an image sensor array of the invention showing incorporation of reset control lines in the image sensor array;

FIG. 4 c is a timing diagram illustrating coordinated exposure control timing pulses and reset control timing pulses according to the invention;

FIGS. 5 a-5 e are various partial exploded top views of an embodiment of a solid state image sensor array according to the invention;

FIG. 5 f is a top perspective view of an image sensor integrated circuit chip incorporating an image sensor array according to the invention with an exploded view portion illustrating a pixel pattern of color sensitive “clusters” of pixels which pattern may be distributed throughout the array;

FIGS. 5 g-5 i are top perspective views of image sensor integrated circuit chips incorporating a linear bar code symbol optimized image sensor array according to the invention with respective exploded view portions illustrating pixel patterns including “zones” of monochrome pixels and “zones” of color sensitive pixels;

FIG. 5 j is a top perspective view of an image sensor integrated circuit chip incorporating a linear symbol optimized image sensor array according to the invention;

FIG. 6 a is a cutaway exploded side view of a monochrome pixel according to one embodiment of the invention;

FIG. 6 b is a top view of the pixel shown in FIG. 6 a;

FIG. 6 c is a cutaway exploded side view of a color sensitive pixel in one embodiment of the invention;

FIG. 6 d is a top view of the pixel shown in FIG. 6 c;

FIG. 7 a is an electrical block diagram of an embodiment of an image sensor according to the invention;

FIG. 7 b is an electrical block diagram of an image sensor array of the invention showing incorporation of reset control lines in the image sensor array;

FIGS. 7 c and 7 d are schematic top views illustrating alternative configurations for a reset control system including separate sets of reset control lines for resetting a first subset of rows of pixels independent of resetting second subset of rows of pixels of an image sensor array according to the invention;

FIG. 8 a is an exploded perspective view of an imaging module according to the invention;

FIGS. 8 b and 8 c are front and side views, respectively, of the imaging module shown in FIG. 8 a;

FIG. 8 d shows an illumination and aiming pattern which may be projected by an optical reader according to the invention;

FIG. 8 e is a top view of an alternative imaging module incorporating a laser based aiming pattern generating system;

FIG. 8 f is a front view of a polarizer plate which may be included as part of an imaging module herein, e.g., the imaging middle shown in FIG. 8 a;

FIGS. 9 a and 9 b are physical form views of various hand held optical readers according to the invention;

FIG. 9 c is a perspective view of a hand held mobile telephone (a “cell phone”) which may incorporate a hybrid monochrome and color image sensor array according to the invention and which may be configured according to the invention;

FIG. 10 is a schematic view of a system incorporating a plurality of optical readers according to the invention;

FIG. 11 is an application schematic view illustrating an optical reader according to the invention being operated to capture image data representing a parcel that carries a plurality of bar code symbols;

FIG. 12 a is an application schematic view illustrating a first optical reader according to the invention and a second remotely located optical reader according to the invention being operated to take first and second digital pictures of a parcel at first and second locations that are a distance apart for purposes of determining whether the parcel was damaged during delivery from the first location to the second location;

FIG. 12 b is another application schematic view illustrating an optical reader being used to take a color picture of a delivery vehicle;

FIG. 13 a is an application schematic diagram according to the invention illustrating an optical reader according to the invention being used to read bar codes of a vehicle and to take color pictures of a vehicle;

FIG. 13 b is a view of a VIN sticker which may be disposed on the vehicle of FIG. 13 a;

FIG. 13 c is a view of a VIN plate which may be disposed on the vehicle of FIG. 13 a;

FIG. 13 d is a view of a vehicle registration sticker which may be disposed on the vehicle of FIG. 13 a;

FIG. 13 e is a view of an optical reader programmed to display a GUI form assisting an application wherein an optical reader, according to the invention, is utilized to decode bar code symbols and to take color pictures of a vehicle;

FIGS. 14 a-14 c are various flow diagrams illustrating the invention;

FIGS. 14 d-14 f are additional flow diagrams illustrating examples of operation of an optical reader according to the invention in an indicia decode mode of operation;

FIGS. 14 g and 14 h are additional flow diagrams illustrating examples of operation of an optical reader according to the invention in a picture taking mode of operation;

FIG. 14 i is a flow diagram illustrating operation of a fusion circuit of an optical reader according to the invention which processes monochrome and color image data to produce a high resolution visual display color frame of image data;

FIGS. 15 a-15 e are various image capture initiation control signal timing diagrams illustrating the invention;

FIGS. 16 a-16 c illustrate various pixelized frames of image data which may be captured by an optical reader according to the invention;

FIG. 17 a is an electrical block diagram of an optical reader according to the invention having a plurality of imaging modules;

FIGS. 17 b and 17 c illustrate alternative hardware blocks that can be utilized with the electrical circuit of FIG. 17 a;

FIGS. 17 d and 17 e illustrate imaging modules which may be utilized with the reader of FIG. 17 a;

FIGS. 17 f and 17 g illustrate exemplary optical readers incorporating a pair of imaging modules;

FIG. 18 a is a schematic view of a cyan-magenta-yellow (CMY) image sensor array in accordance with the invention which may be incorporated into an optical reader according to the invention and which may be controlled to generate both a decode frame of image data and a visual display color frame of image data;

FIG. 19 a is a schematic view of a hybrid monochrome and polarizer image sensor array in accordance with the invention which may be incorporated in an optical reader according to the invention;

FIG. 19 b is a top perspective view of a hybrid monochrome and polarizer image sensor array according to the invention with an exploded view section illustrating a pattern of light polarizing pixels that may be distributed throughout the image sensor array;

FIG. 19 c is a flow diagram illustrating an exemplary operational mode of an optical reader according to the invention which incorporates a hybrid monochrome and polarizer image sensor array according to the invention;

FIGS. 20 a and 20 b are top perspective views of a monochrome polarizer and color sensitive image sensor array according to the invention with an exploded view section illustrating a pattern of light polarizing pixels and color sensitive pixels that may be distributed throughout the array;

FIG. 21 is a schematic view of an image sensor integrated circuit chip incorporating an image sensor array having color sensitive pixels disposed therein with two different periods of distribution;

FIG. 22 a is a schematic block diagram of an autodiscrimination circuit which may be utilized with the invention;

FIG. 22 b is a process for practicing principles of the invention including automatically discriminating between different dataform types;

FIG. 22 c shows one embodiment of a plurality of curvelent detector maps which may be utilized with the invention;

FIG. 22 d shows another embodiment of a plurality of curvelent detector maps which may be utilized with the invention;

FIG. 22 e is a diagrammatic representation of a histogram analysis which may be performed in one embodiment of the invention;

FIGS. 22 f-22 i are diagrammatic representations of an image data segmentation process according to embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

There is provided in one embodiment an optical reader having an image sensor array. In one embodiment, the image sensor array can include a first subset of pixels and a second subset of pixels. The first subset of pixels can be devoid of light polarizing filter elements, and the second subset of pixels can be light polarizing pixels including light polarizing filter elements. An optical reader can be configured to selectively read out image data from an image sensor array's light polarizing pixels.
An optical reader image sensor array of the invention can include light polarizing pixels, each light polarizing pixel having a light polarizing filter element (light polarizing filter) that significantly attenuates polarized light rays generated from an appropriately polarized light source and reflected at a specular angle; thus, reducing the contribution of specularly reflected light rays to generated image signals from the polarizing pixels. In one embodiment, a first subset of pixels of an optical reader image sensor array are monochrome pixels and a second subset of pixels are light polarizing pixels. For decoding decodable indicia in specular reflection read conditions, image data corresponding to the light polarizing pixels can be selectively transferred to a decode circuit, either by way of selecting reading out image data from the light polarizing pixels, or by selectively extracting image data corresponding to light polarizing pixels from a frame of image data including image data in addition to image data corresponding to light polarizing pixels.
In another embodiment, there is provided a picture taking optical reader having a hybrid monochrome and color (monocolor) solid state image sensor array. The hybrid image sensor array comprises a plurality of pixels including a first subset of pixels and a second subset of pixels, wherein the first subset of pixels are monochrome pixels and the second subset of pixels are color sensitive pixels having wavelength selective color filter elements.
In one embodiment, the monochrome first subset of pixels is formed in a checkerboard pattern, and voids are formed at the corners of pixels of the first subset, such that combinations of voids of adjacent pixels define open areas. Pixels of the color sensitive second subset of pixels are formed at the open areas, and wavelength selective filter elements are formed on pixels of the second subset but not on pixels of the first subset.
In another embodiment, an optical reader solid state image sensor array includes a plurality of pixels formed in a plurality of rows on an IC chip in a checkerboard pattern wherein each pixel has approximately the same dimension. The majority of pixels of the image sensor array are monochrome pixels of the first subset. Color sensitive pixels of the second subset are at spaced apart positions and are uniformly or substantially uniformly distributed throughout the image sensor array. Color sensitive pixels may be distributed in the array in a specific pattern of uniform distribution such as a period of P=2, where every other pixel of every other row of the image sensor array is a color sensitive pixel, or a period of P=4 where, for every fourth row of pixels of the array, every fourth pixel is a color sensitive pixel.
A hybrid monochrome and color sensing solid state image sensor array of the invention may be incorporated in an imaging module which, in addition to having an image sensor array constructed in accordance with the invention includes such elements as an imaging lens, an illumination assembly including a field illumination assembly, an aiming illumination assembly and a support member for supporting the above elements. An imaging module, in turn, may be incorporated into a hand held housing which encapsulates and supports the imaging assembly.
Utilizing complementary metal-oxide-silicon (CMOS) integrated circuit fabrication technologies the image sensor array in one embodiment can be made to have selectively addressable pixels. Where the image sensor array is constructed to have selectively addressable pixels, pixels of the first subset of pixels can be selectively addressed independent of the second subset of pixels so that image data corresponding to the first subset of pixels is selectively read out independent of the second subset of pixels. Image sensor arrays having selective read out capability can be provided utilizing alternative fabrication technologies.
In a further aspect, an optical reader according to the invention includes separate and independently controllable reset control lines for resetting monochrome pixels and color sensitive pixels of the image sensor array. During exposure periods for exposing color sensitive pixels, monochrome pixels may be driven into reset. During exposure periods for exposing monochrome pixels, color sensitive pixels may be driven into reset. Driving pixels not being selectively addressed for image data read out into a reset state reduces cross-talk between pixels of the image sensor array.
By incorporating within a single low cost image sensor array a combination of monochrome pixels and color sensitive pixels, an optical reader according to the invention provides indicia decoding performance approximately equal to the performance of an optical reader having an all monochrome image sensor array, and picture taking performance (i.e., the ability to obtain visual display quality color frames of image data) approximately equal to or superior to that of a digital camera incorporating an all color pixel image sensor array, wherein each pixel of the array includes a wavelength selective filter element.
An electrical block diagram of an optical reader 100 according to the invention is shown in FIG. 1 a. Reader 100 includes a solid state image sensor array 182A, incorporated on an image sensor integrated circuit chip 1082A shown in FIG. 1 a as a CMOS image sensor integrated circuit (IC) chip. In an important aspect, as will be described herein, image sensor array 182A includes a plurality of pixels and wavelength sensitive color filter elements associated with a color sensitive subset of the pixels, wherein the remaining pixels external to the color sensitive subset of pixels are devoid of associated wavelength selective filter elements. Because image sensor array 182A includes both monochrome pixels and color sensitive pixels, image sensor array 182A may be termed a hybrid monochrome and color image sensor array. Reader 100 further includes a processor IC chip 548 and a control circuit 552. Control circuit 552 in the embodiment of FIG. 1 a is shown as being provided by a central processing unit (CPU) of processor IC chip 548. In other embodiments, control circuit 552 may be provided by e.g., a programmable logic function execution device such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). Imaging lens 212 focuses images onto an active surface of image sensor array 182A and together with image sensor array 182A forms an imaging assembly 200. Control circuit 552 executes picture taking and indicia decoding algorithms in accordance with instructions stored in program memory EPROM 562 which together with RAM 560 and Flash memory 564 forms a reader memory 566. Reader memory 566 is in communication with processor IC chip 548 via system bus 570. Main processor IC chip 548 may be a multifunctional IC chip such as an XSCALE PXA25x processor IC chip including central processing unit (CPU) 552. Reader 100 further includes a field programmable gate array (FPGA) 580. Operating under the control of control circuit 552, FPGA 580 receives digital image data from image sensor IC chip 1082A and transfers that image data into RAM 560 so that the image data can be further processed (e.g., by the decoding of a bar code symbol). Processor IC chip 548 can include an integrated frame grabber. For example, processor IC chip 548 can be an XSCALE PXA27X processor IC chip with “Quick Capture Camera Interface” available from INTEL. Where processor IC chip 548 includes an integrated frame grabber, the integrated frame grabber may provide the frame acquisition functionality of FPGA 580. Reader 100 further includes an illumination assembly 104 and a manual trigger 216. Image sensor IC chip 1082A in the embodiment of FIG. 1 a includes an on-chip control/timing circuit 1092, an on-chip gain circuit 1084, an on-chip analog-to-digital converter 1086 and an on-chip line driver 1090. An image sensor array which is incorporated into optical reader 100 may take on a variety of forms. In FIG. 1 a reader 100 includes first image sensor array 182A. However, as indicated by hardware block 208, the image sensor array 182A may be replaced. For example, in the embodiment of FIG. 1 b, reader 100 incorporates image sensor array 182B. In other embodiments, optical reader 100 incorporates more than one image sensor array. Various embodiments of image sensor arrays which may be incorporated into reader 100 are described herein.
In a further aspect, reader 100 includes a radio frequency (RF) communication interface 571. Radio frequency communication interface 571 may include one or more radio transceivers. Referring to the schematic diagram of FIG. 1 c, radio frequency communication interface 571 may include one or more of an 802.11 radio transceiver 5712, a Bluetooth radio transceiver 5714, a GSM/GPS radio transceiver 5716 or a WIMAX (802.16) radio transceiver 5718. Radio frequency communication interface 571 facilitates wireless communication of data between device 100 and a spaced apart device 150. I/O communication interface 572 includes one or more serial or parallel hard-wired communication interfaces facilitating communication with a spaced apart device 150 as will be described further in connection with FIG. 10. I/O communication interface 572 may include one or more of an Ethernet communication interface, a universal serial bus (USB) interface, or an RS-232 communication interface. Optical reader 100 may further include a keyboard 508 for entering data, a pointer mover 512 for moving a pointer of a graphical user interface (GUI) and a trigger 216 for initiating bar code reading and/or picture taking. Optical reader 100 may also include a display 504, such as a monochrome or color LED display and a touch screen 504T overlaid over display 504. As shown in the schematic block diagram of FIG. 1 d, display 504 may include a display screen 5042 coupled to display controller 5044 for displaying color image data. Display controller 5044 receives a visual display color frame of image data from control circuit 552, and reformats that data for display depending on the particular requirements of display screen 5042, including the pixel resolution of display screen 5042. All of the components of FIG. 1 a can be encapsulated and supported by a hand held housing 101, e.g., as shown in FIGS. 9 a-9 c. Additional features and functions of the components of reader 100 shown in FIG. 1 a are described herein.
Referring to FIG. 1 e, optical reader 100 may be regarded as having various processing circuits (modules). Indicia decode circuit 1702 receives image data and decodes decodable indicia therein such as bar code indicia and OCR character data. Optical reader 100 can be configured so that indicia decode module 1702 decodes such bar code symbols UPC/EAN, Code 11, Code 39, Code 128, Codabar, Interleaved 2 of 5, MSI, PDF417, MicroPDF417, Code 16K, Code 49, MaxiCode, Aztec, Aztec Mesa, Data Matrix, Qcode, QR Code, UCC Composite, Snowflake, Vericode, Dataglyphs, RSS, BC 412, Code 93, Codablock, Postnet (US), BPO4 State, Canadian 4 State, Japanese Post, KIX (Dutch Post), Planet Code and the like, and such OCR character forms as OCR A, OCR B, and the like. Autodiscrimination circuit 1704 processes received image data and distinguishes between handwritten character data and decodable indicia. Autodiscrimination circuit 1704 may include indicia decode circuit 1702. Autodiscrimination circuit 1704 and indicia decode circuit 1702 may be physically embodied by a combination of control circuit 552 and memory 566. Specifically, control circuit 552 operating under the control of a program stored in memory 562 may process image data stored in memory 560 to decode decodable indicia therein or to discriminate between handwritten character data and decodable indicia. Further aspects of indicia decode circuit 1702 and autodiscrimination circuit 1704 are described in copending U.S. patent application Ser. No. 10/958,779 entitled, System And Method To Automatically Discriminate Between A Signature And A Barcode, filed Oct. 5, 2004 and U.S. patent application Ser. No. 11/077,975, filed Mar. 11, 2005 entitled, Bar Code Reading Device With Global Electronic Shutter Control, both of which are incorporated herein by reference. As will be described further herein, optical reader 100 may further include a demosaicing circuit 1706, and a fusion circuit 1708. Demosaicing circuit 1706 receives as an input a color filter array image data frame (e.g., a Bayer pattern image) and produces as an output a visual display color frame of image data. Fusion circuit 1708 receives as inputs both monochrome and color image data and produces as an output a visual display color frame of image data having a spatial resolution at or on the order of the pixel resolution of the optical reader's hybrid monochrome and color image sensor array. Like circuit 1702, 1704, circuits 1706 and 1708 may be physically embodied by the combination of control circuit 552 and memory 566. Control circuit 552 as well as circuits 1702, 1704, 1706, and 1708 may be incorporated within hand held housing 101 (e.g., as shown in FIGS. 9 a-9 c) or else one or more of circuits 552, 1702, 1704, 1706, and 1708 can be incorporated in a housing of a spaced apart device 150 as described in connection with FIG. 10.
A visual display color frame of image data as referred to herein, in one embodiment is an image frame including a set of color indicating data at each of a plurality of pixel positions, wherein each set of color indicating data represents a color at a discrete position of a target 1850 (shown in FIG. 8 d). Each set of color indicating data includes three color values, e.g., a color scale value representing red, a color scale value representing blue, and a color scale value representing green. Alternatively, the set of color indicating data for each pixel position may include a cyan value, a magenta value and a value representing yellow.
In one specific example, the set of color indicating data for each pixel position of a visual display color frame of image data output by demosaicing circuit 1706 or fusion circuit 1708 are RGB data sets including 24 bits of information, wherein the first 8 bits represent a red color scale value (red value) for the pixel position, the second 8 bits represent a green color scale value (green value) for the pixel position and the third 8 bits represent a blue color scale value (blue value) for the pixel position.
A major feature of the invention is the construction of the optical reader's image sensor array various embodiments of which are shown and described throughout several views including the views of FIGS. 2 a-7 d.
A first embodiment of a hybrid monochrome and color sensitive (monocolor) solid state image sensor array is shown and described in FIG. 1 a and FIGS. 2 a-4 b.
Referring to FIG. 1 a and FIGS. 2 a-4 b, solid state image sensor array 182A includes a monochrome first subset of pixels 250M and a color sensitive second subset of pixels 250C. The first subset of monochrome pixels 250M is formed in a checkerboard pattern and voids 253 as shown in FIG. 2 a are formed at the corners of pixels of the first subset, such that combinations of voids, e.g., voids 253-1, 253-2, 253-3, 253-4 of adjacent pixels define open areas, e.g., open area 255, each open area bounded by four pixels of the first subset. With further reference to image sensor array 182A, pixels 250C forming a second subset of pixels 250C are disposed in the open areas 255, and wavelength selective filter elements, e.g., filter element 260C, 260M, as shown in FIG. 2 b are formed on pixels of the second subset but not on pixels of the first subset. Monochrome pixels 250M as described herein are devoid of color filter elements (color filters). Pixels of the first monochrome pixel subset are in the shape of twelve sided polygons. The pixels are cross-shaped as seen from the top view that is indicated by FIGS. 2 a-2 d (the monochrome pixels are square shaped as modified by the presence of voids 253). Pixels of the color sensitive second subset are square as seen from a top view.
In the version of image sensor array 182A shown in FIG. 2 b, color sensitive pixels 250C of image sensor array 182A include either a cyan (Cy) filter element 260C or magenta (Mg) filter element 260M. In the version of FIG. 2 c, color sensitive pixels 250C of image sensor array 182A include either a red filter element 260R, a green filter element 260G or a blue color filter element 260B (RGB filters). The color sensitive pixels 250C can be distributed throughout image sensor array 182 according to a Bayer pattern wherein there are N blue pixels, N red pixels and 2N green pixels. Color filter elements of any image sensor array pixel as described herein can be deposited on the major body of color sensitive pixels 250C by way of a depository process. As will be explained herein, visual display color image data can be obtained utilizing either the version of image sensor array 182A shown in FIG. 2 b or the version of image sensor array 182A shown in FIG. 2 c, or another version of image sensor array 182A such as a version including cyan, magenta and yellow (CMY) color sensitive pixels. Because cyan and magenta filters require only one dye and not two dyes (as in red, green, and blue filters) a version of image sensor array 182A including cyan and magenta filter elements in place of red, green and blue filter elements allows more light to pass through to a photodetector of the pixels and exhibits a higher signal to noise ratio than a version including red, green and blue filters. Nevertheless, an image sensor array having a combination of red, green and blue (RGB) filter elements may be preferred for certain applications. Referring to FIG. 2 d, image sensor array 182A may include microlenses 320 for directing of light rays incident on image sensor array 182A. Further aspects of microlenses 320, including monochrome pixels, microlenses 320M, and color sensitive pixel microlenses 320C are described herein.
Exploded physical form views of an image sensor pixel array 182A, where array 182A is configured to operate in a global electronic shutter operating mode are shown and described in FIGS. 3 a-3 d. A monochrome pixel 250M of image sensor array 182A is shown in FIGS. 3 a and 3 b. Monochrome pixel 250M includes a photodetector 302 which may be of photodiode or photogate construction, a transfer gate 304, a floating diffusion 306, a reset transistor 307 including reset gate 308, a row select transistor 309 including row select gate 310 and a source follower amplifier transistor 311 including amplifier gate 312. An important feature of pixel 250M is opaque optical shield 316. Opaque optical shield 316, typically comprising metal, shields light rays from components of pixel 250M other than photodetector 302. Accordingly, pixels from each of several rows of image sensor array 182A can be simultaneously exposed to light in a global electronic shutter operating mode without the light rays modulating charges stored in floating diffusion 306 or another storage region. Further aspects of image sensor arrays capable of operating in a global electronic shutter operating mode are described in U.S. patent application Ser. No. 11/077,975 incorporated herein by reference. Referring to additional aspects of pixel 250M, pixel 250M includes microlens 320 which may be disposed on light transmissive protective layer 322. Microlens 320 collects light from a larger surface area than photodetector 302 and directs light toward photodetector 302.
A color sensitive pixel 250C of image sensor array 182A is described with reference to FIGS. 3 c and 3 d. Color sensitive pixel 250C is similar in construction to monochrome pixel 250M. Color sensitive pixel 250C includes a photodetector 302 which may be of photodiode or photogate construction, a transfer gate 304 for transferring charge from photodetector 250C, a floating diffusion 306, a reset transistor 307 including reset gate 308, a row select transistor 309 including row select gate 310 and a source follower transistor amplifier 311 including amplifier gate 312. Color sensitive pixel 250C also includes opaque shield 320 which shields light from light sensitive components of pixel 250C other than photodetector 302. Pixel 250C may also include microlens 320 for increasing the amount of light incident on photodetector 302. In addition to the above elements color sensitive pixel 250C includes a wavelength selective color filter element 260 formed thereon. Wavelength selective color filter element 260 may be disposed intermediate microlens 320 and protective layer 322. In the versions of FIGS. 2 a-2 d, it is seen that each color sensitive pixel 250C has four adjacent monochrome pixels 250M.
Microlenses 320 as shown in FIGS. 3 a and 3 c are also shown in the view of FIG. 2 d. Monochrome pixel microlens 320, 320M and color sensitive microlens 320, 320C may be formed on a microlens array included a plurality of microlenses. With the architecture described wherein color sensitive pixels 250C are disposed in open areas defined by voids of checkerboard pattern of a first monochrome subset of pixels 250M, microlenses 320C of color sensitive pixels 250, 250C have very little (e.g., less than 3.4%) of overlap relative to microlenses 320M.
Color sensitive pixel 250C of image sensor array 182A as best seen by a comparison between FIGS. 3 b and 3 d and consumes a smaller surface area than pixel 250M. In one version, pixel 250M includes an area, as seen from a top view, of about 12 nm by 12 nm while pixel 250C includes an area, as seen from a top view, of about 6 μm by 6 μm. In another version, pixel 250M includes a top surface area of about 6 μm by 6 μm, while pixel 250C includes a top surface area of about 3 μm or 3 μm. Size reductions of pixel 250M or pixel 250, 250C may be made at low cost by reducing the number of transistors of pixel 250M and/or pixel 250C.
A transistor count of a pixel 250C of image sensor array 182A may readily be reduced by eliminating optically shielded floating diffusion 306 in which charges are stored on a temporary basis to facilitate global electronic shutter operation. Accordingly, in one embodiment, monochrome pixels 250M of image sensor array 182A have more transistors than color sensitive pixels 250C but are capable of being exposed on a global electronic shutter basis, whereas color sensitive pixels 250C have fewer transistors than monochrome pixels 250M but are not capable of being exposed on a global electronic shutter basis. In yet another embodiment with reference to image sensor array 182A having smaller dimensioned color sensitive pixels than monochrome pixels, the relatively larger monochrome pixels 250M have a transistor count sufficient to facilitate global shutter operation, but the relatively smaller color sensitive pixels 250C are passive pixels requiring off-pixel amplification, and comprise a single transistor each. Further aspects of global electronic shutter and rolling shutter operations relative to image sensor arrays which may be incorporated into reader 100 are described herein.
Referring to FIG. 4 a, a high level electrical block diagram of image sensor array 182A is shown. According to one version, image sensor array 182A is an active pixel image sensor array of complementary metal oxide semiconductor (CMOS) construction such that each pixel 250M, 250C, whether from the monochrome first subset of pixels or the color sensitive second subset of pixels is an active pixel including a pixel amplifier 311 for amplifying signals corresponding to light incident on photosensitive region 252. Each pixel 250M, 250C may also include an optically shielded storage element 306. Image sensor array 182A further includes two-dimensional grid of interconnects 262 which are in electrical communication with respective column circuitry 270 and row circuitry 296. Row circuitry 296 and column circuitry 270 enable such processing and operational tasks as selectively addressing pixels, decoding pixels, amplification of signals, analog-to-digital conversion, applying timing, read out and reset signals and the like.
Among the control lines forming interconnect grid 262 of image sensor array 182A are pixel reset control lines. When pixels are reset by application of an appropriate control signal on a reset control line, residual charges which have accumulated on the pixels are connected temporarily to VDD so that built up charges on pixels of the image sensor array drain out of the pixels. In accordance with the invention, image sensor array 182A includes separate reset control lines for monochrome pixels 250M and color pixels 250C. Referring to FIG. 4 b, image sensor array 182A may be constructed so that image sensor array 182A has a first set of reset control lines 262R-M for resetting monochrome pixels 250M and a second set of reset control lines 262R-C for resetting color pixels 250C.
In certain operating modes optical reader 100 selectively reads out a windowed frame of image data comprising image data from monochrome pixels 250M. In other operating modes, optical reader 100 selectively reads out a windowed frame of image data comprising image data from color pixels 250C. In accordance with the invention, a reset control timing pulse can be applied to image sensor array 182A during the time that a windowed frame of image data is being captured to reset pixels of image sensor array 182A that are not being selectively addressed for image data read out. As shown by the timing diagram of FIG. 4 c, an exposure control timing pulse 354 can be coordinated with a reset control timing pulse 370.
With further reference to FIG. 4 c, exposure control timing pulse 354 may control exposure of monochrome pixels 250M of image sensor array 182A (or alternatively, color pixels 250C) of image sensor array 182A, while reset control timing pulse 370 drives pixels not being selectively addressed into a reset state. When pixels are reset, charges built up on pixels tend to be drained out of the pixels. Further, it is believed that photons entering pixels driven into reset may be refracted so that fewer photons become incident on neighboring pixels being exposed for image data read out. Accordingly, coordinating the timing of an exposure control pulse 354 for exposing selectively addressed pixels and a reset control timing pulse 370 for resetting pixels not being selectively addressed reduces cross talk between pixels.
Referring again to the view of FIG. 4 b, image sensor array 182A may be constructed so that the presence of multiple reset control lines 162R-C, 162R-M do not substantially decrease the fill factor of pixels of image sensor array 182A. FIG. 4 b shows a schematic top view of multiple reset control lines 162R-M, 162R-C incorporated in image sensor array 182, 182A. According to the invention, control lines 162R-M, 162R-C can be incorporated in image sensor array 182A in a layered manner so that for a substantial portion of image sensor array 182A, control lines 164R-M have x, y positions that coincide with x, y positions of control line 164R-C (axes are defined in FIG. 8 a). Control lines 164R-C in the embodiments of FIG. 4 b are installed at a different height (a different Z axis position) within image sensor array 182A such that control lines 162R-M and 162R-C, for substantial length of the control lines, have common x, y positions. Installing the multiple control lines to be on top of one another so that the control lines have a common x, y axis position within image sensor array 182A reduces the amount of fill factor degradation which would otherwise result from installation of an additional set of reset control lines within image sensor array 182A.
An alternative construction for an image sensor array according to the invention is described with reference to FIGS. 5 a-7 b. In the embodiment of FIGS. 5 a-7 b image sensor array 182B includes a plurality of square shaped pixels (as seen from a top view) in a checkerboard pattern, each of the pixels having substantially the same dimensions. Each pixel 250M, 250C of image sensor array 182B may be constructed to have approximately the same top surface dimensions as seen from the top views of FIGS. 5 a-5 i and approximately the same side view cross-sectional dimensions as seen from the cross-sectional views of FIGS. 6 a-6 d. Image sensor array 182B is similar to the construction of a standard off-the-shelf monochrome image sensor array except that select ones of the pixels of the image sensor array have an associated wavelength selective color filter element. Solid state image sensor array 182B includes a plurality of pixels formed in a plurality of rows. In the version of FIGS. 5 a-5 e, a monochrome first subset of pixels 250M comprise the majority of pixels of the array. Wavelength selective color filter elements 260 are included in the second subset of color sensitive pixels 250C. The color sensitive second subset of pixels 250C comprises pixels at spaced apart pixel positions uniformly distributed or substantially uniformly distributed throughout the plurality of pixels forming the image sensor array 182B. In the embodiment of FIGS. 5 a and 5 b, every other pixel in every other row of pixels (e.g., pixel row 2, 4, 6 . . . ) has an associated wavelength selective color filter element. In one example of the invention, image sensor array 182B can be provided by including an appropriately designed color filter array on an image sensor array of an MT9M111 Digital Clarity SOC 1.3 megapixel CMOS image sensor IC chip of the type available from Micron, Inc., an MT9V022 image sensor IC chip also available from Micron, Inc. or a VV6600 1.3 megapixel CMOS image sensor IC chip of the type available from STMicroelectronics. Other image sensor IC chips which can be utilized to provide image sensor array 182B include MT9M413 image sensor IC chip available from Micron, Inc., a KAC-0311 image sensor IC chip manufactured by Kodak, Inc. and a KAI-0340 image sensor IC chip also manufactured by Kodak, Inc. Operational aspects of the referenced KAI-0340 image sensor IC chip are described further herein. Various manufacturer product description materials respecting certain of the above image sensor IC chips are appended to Provisional Patent Application No. [not yet assigned] filed Jun. 22, 2005 (Express Mail Label No. EV554216715US) and Provisional Patent Application No. [not yet assigned] filed Jun. 27, 2005 (Express Mail Label No. EV554216661US) which are incorporated herein by reference. The above commercially sold image sensor IC chips can be utilized (with additions or replacements of filter elements as are necessary) to provide any one of image sensor arrays 182B, 182C, 182D, 182F, 182G, 182H described herein.
The above referenced MT9V022 and MT9M413 image sensor IC chips manufactured by Micron, Inc., and KAC-0311 image sensor IC chip by Kodak, Inc. are CMOS image sensor IC chips that may be operated in a global electronic shutter mode such that all rows of pixels subject to image data read out have common exposure periods; that is, all rows of pixels subject to image data read out for reading out a frame of image data (i.e., full frame or “windowed frame”) have a common exposure start time and a common exposure stop time. For global electronic shutter operation, an exposure control timing pulse, as will be described herein is applied to the image sensor array. Exposure of each row of pixels subject to image data read out begins at the leading edge of the exposure control timing pulse and ends at the falling edge of the exposure control timing pulse. In its technical literature, Micron, Inc. uses the trademark TRUESNAP with reference to a global electronic shutter operating mode.
Referring to FIG. 5 b, wavelength selective color filter elements (filters) formed on color sensitive pixels 250, 250C may be a combination of cyan filter elements 260C and magenta color filter elements 260M. As shown in FIG. 5 a, wavelength sensitive filters of color sensitive pixels 250C may also be a combination of red filter elements 260R, green filter elements 260G and blue filter elements 260B. Because cyan and magenta filters require only one dye and not two dyes (as in red green and blue filters), the version of FIG. 5 b allows more light to pass through to a photodetector (e.g., photodetector 302 as shown in FIG. 6 c) and exhibits a higher signal to noise ratio than the embodiment of FIG. 5 b. Nevertheless, the version of FIG. 5 a may be preferred for certain applications.
In the embodiment of FIGS. 5 a-7 d, hybrid monochrome and color image sensor 182B can be made by including an appropriately designed color filter array on a commonly available, off-the-shelf image sensor array in a standardly known checkerboard pattern, each pixel of the array having substantially the same dimensions. A larger portion of image sensor array 182B is shown in FIG. 5 c, where pixels designated by the letter “c” are color sensitive pixels 250C and pixels not designated by the letter “c” are monochrome pixels 250M. In the example of FIG. 5 c, color sensitive pixels are formed on array 182B with a period of P=2, meaning the every other pixel of every other row of pixels is a color sensitive pixel 250C. In the version of FIG. 5 d, color sensitive pixels are formed on array 182B with a period of P=3, meaning that every third pixel of every third row is a color sensitive pixel 250C. In the version of FIG. 5 e, color sensitive pixels, c, are formed with a period of P=4, meaning that every fourth pixel from every fourth row of pixels is a color sensitive pixel 250C. In the versions of FIGS. 5 a-5 e, each color sensitive pixel 250C has eight adjacent monochrome pixels 250M (two side adjacent, one top adjacent, one bottom adjacent and four corner adjacent).
Additional views of image sensor array 182B including a subset of monochrome pixels 250M and a subset of color sensitive pixels 250C, wherein each pixel of the image sensor array has substantially equal dimensions are shown and described in connection with FIGS. 5 f-5 j.
Referring to the version of FIG. 5 f, image sensor array 182B includes the first subset of monochrome pixels 250M and a second subset of color sensitive pixels 250C. The color sensitive pixels 250C of image sensor array 182B in the version of FIG. 5 f are formed in clusters such as cluster 257R, cluster 257G and cluster 257B.
Each cluster 257 in the version of FIG. 5 f includes a plurality of pixels in successive horizontally adjacent pixel positions, such that each pixel of the cluster is horizontally adjacent to at least one other color sensitive pixel. Color sensitive clusters of pixels are distributed uniformly or substantially uniformly throughout image sensor array 182B. Clusters may be formed in accordance with the standardized color filter pattern such as an RGB Bayer pattern or a cyan-magenta-yellow (CMY) pattern. Each cluster may have a plurality of pixels with each pixel of every individual cluster having a filter element of the same wavelength rating. In the specific version shown in FIG. 5 f, clusters are distributed throughout image sensor array 182B in a pattern that is accordance with the pattern of Bayer color filter array.
Cluster 257G includes three horizontally adjacent green pixels. Cluster 257R includes three horizontally adjacent red pixels. Cluster 257B includes three horizontally adjacent blue pixels. As will be described further in connection with FIG. 7 c, the version of image sensor array 182B including a distribution of color sensitive pixels in horizontally arranged clusters as shown in FIG. 5 f is particularly useful where it is desired to include in image sensor array 182B separate and independently controllable reset control lines 262R-M and 262R-C for separately and independently resetting monochrome pixels of image sensor array 182B and color sensitive pixels of image sensory array 182B without increasing the thickness of image sensor array 182B.
Referring now to the versions of image sensor array 182B shown in FIG. 5 g-5 j, image sensor array 182B having a subset of monochrome pixels in a subset of color sensitive pixels may be configured to include “zones” of monochrome pixels and “zones” of color sensitive pixels. A “zone” of pixels herein is a collection of positionally related pixels at a specified area of an image sensor array each having a color filter element or alternatively, each being without a color element. Examples of zones described herein comprise all pixels of one row of pixels or all pixels of each of several consecutive rows of pixels. In the version of FIG. 5 g, image sensor array 182B includes two color sensitive zones of pixels 2500C and a single monochrome zone of pixels 2500M. Each zone of pixels comprises a plurality of horizontally, vertically or diagonally adjacent pixels. The plurality of pixels of a monochrome zone of pixels, e.g., zone 2500M are all devoid of a color sensitive filter element. The plurality of adjacent pixels in a color sensitive zone of pixels, e.g., zone 2500C, all include a color sensitive filter element.
Referring to the version of FIG. 5 g, monochrome zone of pixels 2500M is interposed between a pair of color sensitive zones of pixels 2500C. Monochrome zone of pixels 2500M in the version of FIG. 5 g comprises a single row of pixels of image sensor array 182B at or approximately the center of image sensor array 182B. The first color sensitive zone of pixels of an image sensor array 182B includes all pixels from the row of pixels of zone 2500M up to the top row of image sensor array 182B. The second color sensitive zone of pixels 2500C in the version of FIG. 5 g includes all pixels from all rows from the center row monochrome zone of pixels 2500M down to the bottom row of pixels of image sensor array 182B. The color filter elements of color sensitive pixels 250C of image sensor array 182B may be formed in a standard color filter pattern, e.g., an RGM Bayer color filter pattern or a CMY pattern.
Referring to FIG. 5 h, another version of image sensor array 182B is shown and described. The version of FIG. 5 h is similar to the version of FIG. 5 g except that the monochrome zone of pixels 2500M is expanded to include ten consecutive rows of pixels at the center or approximately the center of image sensor array 182B.
In the version of image sensor array 182B as shown in FIG. 5 i, a single color sensitive zone of pixels 2500C is interposed between two relatively small width monochrome zones of pixels 2500M formed at the top and bottom of image sensor array 182B respectively. In the version of image sensor array 182B shown in FIG. 5 a, the first monochrome zone of pixels 2500M comprises the first ten rows of pixels of image sensor array 182B and a second monochrome zone of pixels 2500M includes pixels of the bottom ten rows of image sensor array 182B. Color sensitive zone of pixels 2500C in the version of FIG. 5 i includes all pixels of the array excluding the first ten and the last ten rows of pixels of image sensor array 182B. In the versions of FIG. 5 h and FIG. 5 i, the pixels of the color sensitive zones 2500C shown may include color filter elements in accordance with the pattern of a standardized color filter array, e.g., an RGB Bayer pattern or a CMY pattern.
The version of image sensor array 182B shown in FIG. 5 j is similar in construction to the version of FIG. 5 g except that the version of FIG. 5 j includes additional monochrome zones of pixels 2500M. In the version of FIG. 5 j image sensor array 182B includes a pair of diagonal zones of monochrome pixels 2500M-D extending through a center (actual or approximate) of image sensor array 182B and a vertically extending zone of monochrome pixels 2500M-V extending through a center of image sensor array 182B. The linear zones of monochrome pixels 2500M shown in the version of FIG. 5 j may include a minor dimension equal to one pixel width or more than one pixel width. For example, the vertically extending monochrome zone of pixels 2500M of FIG. 5 j may include pixel positions of one column of pixels or of a plurality of columns of pixels. Likewise, the diagonally extending linear monochrome zones of pixels 2500M of FIG. 5 g may include pixel positions of a single diagonal row of pixels or alternatively, of a plurality of diagonal rows of pixels.
It will be seen that the versions of image sensor array 182B shown in FIGS. 5 g-5 j are particularly well suited for use in picture taking optical readers which in bar code decoding applications are expected to decode linear bar code symbols. The image sensor arrays of FIGS. 5 g-5 j may be referred to as linear symbol optimized image sensor arrays. As will be described in further detail herein, image data corresponding to monochrome zones of pixels 2500M in the versions of FIGS. 5 g-5 j can be selectively addressed and read out independently of image data from rows from color sensitive zones 2500C of pixels. In bar code decoding applications, control circuit 552 may selectively address pixels of monochrome zones 2500M and read out image data from monochrome zones of pixels 2500M as shown in FIGS. 5 g-5 i and transfer such image data to indicia decode circuit 1702 for decoding of a linear bar code symbol. For picture taking applications, control circuit 552 may selectively address pixels of a color sensitive zone or zones of pixels 2500C and selectively read out image data from color sensitive zone or zones 2500C and process such color image data into a visual display color frame of image data. The processing as will be explained further herein may include such steps as executing a demosaicing routine to convert color filter pattern image data into a visual display format and interpolation of color pixel values corresponding to the missing pixel positions at the pixel positions occupied by a monochrome zone or zones 2500M of pixels.
In FIGS. 6 a-6 d, exploded physical form view of pixels of image sensor array 182, 182B are shown. A monochrome pixel 250M of image sensor array 182B is shown in FIGS. 6 a and 6 b. Pixel 250M includes a photodetector 302 which may be of photodiode or photogate construction, a transfer gate 304, a floating diffusion 306, a reset transistor 307 including reset gate 308, a row select transistor 309 including row select gate 310 and a source follower amplifier transistor 311 including amplifier gate 312. An important feature of pixel 250M is opaque optical shield 316. Opaque optical shield 316, typically comprising metal, shields light rays from components of pixel 250M other than photodetector 302. Accordingly, pixels from each of several rows of image sensor array 182A can be simultaneously exposed to light in a global electronic shutter operating mode without the light rays modulating charges stored in floating diffusion 306 or another storage region. Further aspects of image sensor arrays capable of operating in a global electronic shutter operating mode are described in U.S. patent application Ser. No. 11/077,975 incorporated herein by reference. Referring to additional aspects of pixel 250M, pixel 250M includes microlens 320 which may be disposed on light transmissive protective layer 322. Microlens 320 collects light from a larger surface area than photodetector 302 and directs light toward photodetector 302.
A color sensitive pixel 250C of image sensor array 182B is described with reference to FIGS. 6 c and 6 d. Color sensitive pixel 250C is similar in construction to monochrome pixel 250M. Color sensitive pixel 250C includes a photodetector 302 which may be of photodiode or photogate construction, a transfer gate 304 for transferring charge from photodetector 250C, a floating diffusion 306, a reset transistor 307 including reset gate 308, a row select transistor 309 including row select gate 310 and a source follower transistor amplifier 311 including amplifier gate 312. Color sensitive pixel 250C also includes opaque shield 320 which shields light from light sensitive components of pixel 250C other than photodetector 302. Pixel 250C may also include microlens 320 for increasing the amount of light incident on photodetector 302. In addition to the above elements, color sensitive pixel 250C includes a wavelength selective color filter element 260 formed thereon. Wavelength selective color filter element 260 may be disposed intermediate microlens 320 and protective layer 322.
A high level electrical block diagram of image sensor array 182B is shown in FIG. 7 a. Image sensor array 182B may be of CMOS construction and may be an active pixel image sensor array such that each pixel 250 of image sensor array 182B includes a pixel amplifier 311. Each pixel 250 of image sensor array may further have a photosensitive region 252 and an optically shielded storage element 306. Image sensor array 182B further includes a two-dimensional grid of interconnects 262 which are in electrical communication with respective column circuitry 270 and row circuitry 296. Row circuitry 296 and column circuitry 270 enable such processing and operational tasks as selectively addressing pixels, decoding pixels, amplification of signals, analog-to-digital conversion, and applying timing, read out and reset signals.
Reset control lines of interconnect grid 262 are shown in FIG. 7 b. Image sensor array 182B may have multiple sets of reset control lines so that monochrome pixels 250M of image sensor array 182B can be reset independently of color sensitive pixels 250C of image sensor array 182B as described previously in connection with the description of image sensor array 182B. According to the invention, control lines 262R-M, 262R-C can be incorporated in image sensor array 182B in a layered manner so that for a substantial portion of image sensor array 182B, control lines 262R-M have x, y positions that coincide with x, y positions of control line 262R-C (axes are defined in FIG. 8 a). Control lines 262R-C in the embodiment of FIG. 7 b are installed at a different height (a different Z axis position) within image sensor array 182B relative to control lines 262R-C such that control lines 262R-M and 262R-C, for substantial length of the control lines, have common x, y positions. Installing the multiple control lines to be on top of one another so that the control lines have a common x, y axis position within image sensor array 182B reduces the amount of fill factor degradation which would otherwise result from installation of an additional set of reset control lines within image sensor array 182B.
Referring to FIGS. 7 c and 7 d, image sensor array 182B may be configured to include separate and independent reset control lines for separately and independently resetting monochrome pixels 250M and color sensitive pixels 250C without increasing the overall thickness of image sensor array 182B. While disposing reset control lines on top of one another as described in connection with FIGS. 4 b and 7 b provides significant advantages; the image sensor array is made thicker with such arrangement which adds to manufacturing costs. Referring to FIG. 7 c, a version of image sensor array 182B is illustrated having a first set of reset control lines 262, 262R-M for resetting monochrome pixels 250M and a second set of reset control lines 262, 262R-C for resetting color sensitive pixels 250C of image sensor array 182B. The reset control line configuration of FIG. 7 c may be utilized with the color sensitive pixel distribution shown in FIG. 5 f to provide an image sensor array 182B having separate and independently controllable reset control lines for separately resetting monochrome pixels 250M and color sensitive pixels 250C and which exhibits a thickness equal to a thickness of a commonly available off-the-shelf image sensor array. In the version of image sensor array 182B shown in FIG. 7 c, the reset control lines of monochrome pixel rows are electrically connected together and the reset control lines of rows of pixels including color sensitive pixels are electrically connected together. The commonly connected reset control lines of the monochrome pixel rows are designated with the reference numeral 262, 262R-M, while the commonly reset control lines of the rows including color sensitive pixels are designated with the reference numeral 262, 262R-C. In the version of FIG. 5 f and FIG. 7 c, every fourth row of pixels of image sensor array 182B includes clusters of color sensitive pixels 257R, 257G, 257B. As shown in FIG. 7 c, with reset control lines 262, 262R-C of rows including color sensitive pixels 250C electrically connected together, all rows of image sensor array 182B including color sensitive pixels 250C may be driven into reset by application of a reset control signal on common reset control line 262, 262R-C. Likewise, all rows of pixels including only monochrome pixels 250M (the monochrome row of pixels) can be driven into reset by applying a reset control signal on common monochrome pixel reset control line 262, 262R-M. With further reference to the version of image sensor array 182B shown in FIG. 7 c, monochrome pixels 250M of image sensor array 182B may be driven into reset when pixels 250C are exposed for image data read out of color image data.
It is noted that with the configuration of FIG. 7 c, adjacent monochrome pixels 250M-A adjacent to an end pixel, e.g., pixel 250C-E of a color sensitive pixel cluster, e.g., cluster 257R are not driven into reset during exposure periods of color sensitive pixels 250C. However, according to the invention in one example, image data corresponding only to a center pixel 250C-I of each color sensitive horizontally arranged cluster (and not the end pixels 250C-E) may be selectively addressed during read out of color image data. The presence of each lateral color filter element at the end pixels 250C-E, which are not addressed for image data read out, reduces the effect of cross talk attributable to photons entering image sensor array 182B at an angle through end pixels 250C, 250C-E.
Another configuration for providing separately and independently resetting monochrome pixels 250M and color sensitive pixels 250C of image sensor array 182B is shown and described with reference to FIG. 7 d. In the version of FIG. 7 d, image sensor array 182B includes a plurality of rows of pixels including all monochrome pixels 250M followed by a plurality of rows of pixels that include color sensitive pixels 250C only. The monochrome rows of pixels 250M form a first subset of pixels and the color sensitive pixels 250C form a second subset of pixels. The reset control lines for resetting the first subset of pixels can be made separate and independent of the reset control lines for controlling the second subset of pixels by electrically connecting the reset control lines of the first subset of pixels together and then separately electrically connecting together the reset control lines of the second subset of pixels. The common control lines of the first subset of monochrome pixels 250M in the version of FIG. 7 d are designated with reference numeral 262, 262R-M while the common control lines of the second subset of color sensitive pixels 250C in the version of FIG. 7 d are designated with the reference numeral 262, 262R-C. It will be seen that the configuration of FIG. 7 d facilitating separate and independent control of monochrome pixels 250M and color sensitive pixels 250C can be utilized with the line art symbol optimized versions of image sensor array 182B shown and described in FIGS. 5 g-5 i having “zones” of monochrome or alternatively color sensitive pixels 250C that extend entire rows of image sensor array 182B.
Referring to FIG. 7 d, color sensitive pixels 250C may be driven to reset during exposure periods for monochrome pixels 250M by application of a common reset control signal on reset control line 262, 262R-M during exposure of color sensitive pixels 250C for read out of color image data. Similarly color sensitive pixels 250C may be driven into reset by application of a reset control signal on common reset control line 262, 262R-C during exposure periods of monochrome pixels 250M for read out of image data from monochrome pixels 250M.
Features respecting specific embodiments of an image sensor array according to the invention have been described in connection with the views of FIGS. 2 a-4 c (image sensor array 182A), and the views of FIGS. 5 a-7 d (image sensor array 182B). General features of an image sensor array which may be incorporated into optical reader 100 (that is, features which can be incorporated in the image sensor array, whether of the embodiment labeled 182A, the embodiment labeled 182B, or another embodiment such as CMY image sensor array 182C, RGB image sensor array 182D, monochrome linear image sensor array 182E, monochrome area image sensor array 182F, monochrome and polarizer image sensor array 182G, or monochrome color and polarizer image sensor array 182H) are now described.
Optical reader 100 can be programmed or otherwise be configured to selectively address a first plurality of pixels in an image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H independently of selectively addressing a second plurality of pixels of the image sensor array so that image data can be read out of the first plurality of pixels independently of the second plurality of pixels. In one operating mode optical reader 100 selectively addresses the first subset of pixels and reads out image data from first subset of pixels independently of the second color sensitive subset of pixels. In another operating mode optical reader 100 selectively addresses the second subset of pixels and reads out image data from the second subset of pixels independently of the first subset of pixels 250M. Where optical reader 100 selectively addresses and selectively reads out only a subset of pixels of an image sensor array, the resulting frame of image data read out of the image sensor array may be referred to as a “windowed frame” of image data. When a windowed frame of image data is read out, the frame rate of the image sensor array is normally increased relative to a normal frame rate of the image sensor array.
Image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H can be configured to have a rolling shutter operating mode and a global shutter operating mode. When a rolling shutter operating mode is entered, rows of pixels of image sensor array are exposed sequentially. The term “rolling” shutter is used because when in a rolling shutter operating mode an exposure period for a row of pixels generally begins prior to a time an exposure period for a previous row has ended.
When operated in a global electronic shutter operating mode, pixels from several rows of an image sensor array are exposed simultaneously. That is, when operated in a global electronic shutter operating mode, transistor components (for example, transfer gates 304 and reset gates 308 of the array as shown in the embodiments of FIGS. 3 a and 6 a) forming an electronic shutter an image sensor array are controlled in a coordinated manner so that a plurality of rows of pixels are exposed simultaneously and have common exposure periods. In a global electronic shutter operating mode, electronic shutter components of the array are controlled so that the common exposure period for each of the plurality of rows of pixels begins at a common exposure start time (via control of reset gates 308) and ends at a common exposure stop time (via control of transfer gates 304). As explained herein, each pixel of the array may store a charge in an optically shielded storage region during the common exposure period. For facilitating a global electronic shutter operating mode, an exposure control timing pulse 354, 354′, 354″, 354″′ can be applied to an image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H, as is described in further detail in connection with the timing diagrams of FIGS. 15 a-15 e. An exposure control timing pulse 354, 354′, 354″, 354″′ controls the timing for exposure of each row of pixels of image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H being exposed. The exposure period for each row of pixels the image sensor array being subject to image data read out begins at the leading edge of exposure control timing pulse 354, 354′, 354″, 354″′ and ends at the falling edge of exposure control timing pulse 354, 354′, 354″, 354″′. For construction of an image sensor array having a global electronic shutter operating mode each pixel of the array is equipped with additional circuit elements as is described herein.
Image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H of optical reader 100 may be constructed to be operated in a rolling shutter mode of operation only; that is, in one specific embodiment an image sensor array of optical reader 100 can only be controlled to expose pixels of the image sensor array on a rolling shutter basis and cannot be controlled so that pixels of image sensor array are exposed on a global electronic shutter basis. In another embodiment, an image sensor array incorporated in optical reader 100 is constructed to be operated in a global electronic shutter operational mode only and is incapable of operation in a rolling shutter mode.
Image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H can be constructed to be operated in either of a global electronic shutter operation mode or a rolling shutter operational mode. Where an image sensor array incorporated in optical reader 100 is constructed to be operational in either of a rolling shutter operational mode or a global shutter operational mode, the switching between rolling shutter and global shutter operational modes may be made in response to a receipt of operator instructions to change the shutter mode. The switching between rolling shutter and global shutter operational modes may also be automatic and dynamic in response to the sensing of a predetermined criteria being satisfied. An image sensor array equipped optical reader 100 having both rolling shutter and global shutter operational modes is described in U.S. patent application Ser. No. 11/077,975, filed Mar. 11, 2005 entitled, Bar Code Reading Device With Global Electronic Shutter Control, which is incorporated herein by reference. An image sensor array constructed to be operated in either of a rolling shutter or global shutter operational mode is described in U.S. Pat. No. 6,552,323 entitled, “Image Sensor With A Shared Output Signal Line” which is incorporated by reference.
Image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H can be constructed so that certain pixels of the image sensor array are capable of being exposed on either a rolling shutter basis or a global shutter basis and certain other pixels of the image sensor array are capable of being exposed only on a rolling shutter basis and are not capable of being exposed on a global electronic shutter basis.
It has been described with reference specifically to image sensor array 182A, and image sensor array 182B that it may be advantageous to incorporate into an image sensor array of optical reader 100 separately controllable reset control lines 262, 262R-M and 262, 262R-C for resetting monochrome pixels separately and independently of color sensitive pixels to thereby reduce pixel cross talk. It will be understood that it may be advantageous to incorporate separately and independently controllable reset control lines into an image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H according to the invention whenever image data is selectively read out of a first subset of image data and it is desired to reduce cross talk from pixels of the image sensor array external to the first subset of pixels. For example, in optical reader 100 incorporating a cyan-magenta-yellow (CMY) image sensor array 182C as shown in FIG. 18 c, it may be advantageous to incorporate separate reset control lines for resetting magenta and cyan pixels separately from yellow pixels so that when yellow pixels are exposed for read out of decode frame yellow pixel image data for transmission to decode circuit 1792, the remainder of the pixels of the array, i.e., the cyan and magenta pixels can be set to reset to eliminate electron diffusion cross talk and to reduce photon penetration cross talk. When hand held optical reader 100 incorporates a hybrid monochrome and polarizer image sensor array 182G as shown in FIG. 19 b or the monochrome color and polarizer image sensor array 182H as shown in FIGS. 20 a and 20 b, it may be beneficial to incorporate into image sensor array 182 separately controllable reset control lines for controlling the reset of pixels external to the polarizing pixels so that when the polarizing pixels are exposed for read out of image data from the polarizing pixels, the remaining pixels of the image sensor array are set to reset to reduce cross talk from the pixels external to the polarizing pixels.
While an image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H is conveniently provided by a CMOS image sensor array fabricated utilizing complementary metal-oxide-silicone integrated circuit fabrication technologies, an image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H may also be a charge coupled device (CCD) image sensor array, or a CID image sensor array or an image sensor array of another fabrication technology. In various embodiments of the invention described herein, it is advantageous to read out less than a full frame of image data, i.e., a read out of a “windowed frame” of image data which may also be referred to as an image region of interest (ROI). An example of a CCD image sensor array integrated circuit chip having windowing capability is the KODAK KAI-0340 image sensor array IC chip available from Eastman Kodak Corporation of Rochester, N.Y. The KAI-0340 image sensor array IC chip has various operational modes that are selectable utilizing various input switch setups. For example, setting a SW1 switch to the HIGH position causes charge in outer vertical resisters of the image sensor array to be dumped before it reaches the horizontal register, facilitating the selective read out of image data from center columns of the array only. Setting the SW2 switch of the KAI-0340 image sensor array chip changes diode transfer clock timing such that only charge from the center rows is transferred to vertical registers, facilitating the selective read out of image data from center rows of the image sensor array only. Accordingly, where image sensor array 182B is configured according to the version shown in FIG. 5 h having center rows of monochrome pixels defining a monochrome pixel zone 2500M and where the image sensor array is a CCD KAI-0340 image sensor array, image data from the center rows can be read out by selecting a preconfigured operating mode of the image sensor array chip. Additional “windowed frame” patterns can be selectively read out of a CCD image sensor array by varying the speed of a pixel clock timing control timing pulse that controls the speed with which a pixel is clocked. Invalid or null data can be clocked out of a CCD pixel by speeding up a pixel clock signal. Varying a pixel clock control signal between valid data yielding rates and invalid data yielding rates during the reading out of image data from a CCD image sensor array yields a windowed frame of image data comprising valid image data clocked out at normal speed and invalid image data clocked out at high speed. Image data can also be selectively read out of a CCD image sensor array by selectively gating to output circuitry of the CCD image sensor array image data corresponding to select pixels of the image sensor array. It will be seen that for any application described herein wherein a windowed frame of image data is read by selective addressing of pixels from a CMOS image array, a CCD image sensor array supporting windowing capability may be substituted therefore to provide selective read out functionality.
Additional aspects of the invention are described with reference to the physical form views of FIGS. 8 a-8 c and the physical form views 9 a, 9 b and 9 c. In the physical views of FIGS. 8 a-8 c, an imaging module onto which an image sensor chip may be incorporated is described. With reference to FIGS. 9 a, 9 b and 9 c, hand held housings for supporting and encapsulating an imaging module including an image sensor chip are described.
An optical reader 100 of the invention, as shown in the embodiment of FIGS. 8 a-8 c, may include an imaging module such as imaging module 1802A. Imaging module 1802A as shown in FIGS. 8 a-8 c incorporates certain features of an IT4000 imaging module herein and additional features. IT4000 imaging modules are available from Hand Held Products, Inc. of Skaneateles Falls, N.Y. Imaging module 1802A includes first circuit board 1804 carrying light sources 160 a, 160 b, while second circuit board 1806 carries light sources 160 c, 160 d, 160 e, 160 f, 160 g, 160 h, 160 i, 160 j, 160 k, 160 l, 160 m, 160 n, 160 o, 160 p, 160 q, 160 r, 160 s, and 160 t (hereinafter 160 c through 160 t). First circuit board 1804 also carries image sensor array 182, which is integrated onto image sensor IC chip 1082. Image sensor IC chip 1082 and image sensor array 182 in FIG. 8 a are generically labeled with the reference numerals “1082” and “182” respectively in FIGS. 8 a-8 d to indicate that any one of the specifically described image sensor IC chips 1082A, 1082B, 1082C, 1082D, 1082E, 1082F, 1082G, 1082H described herein or any one of the specifically described image sensor arrays 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H described herein may be incorporated into imaging module 1802A. The various image sensor IC chips and image sensor arrays can also be incorporated in another imaging module described herein such as imaging module 1802B, 1802C, 1802D, and 1802E. Imaging module 1802C shown in FIG. 8 e is a laser aiming IT4300 imaging module of the type available from Hand Held Products, Inc. The laser aiming IT4300 imaging module includes a plurality of illumination LEDs e.g., LED 160, and an aiming pattern generator comprising a laser diode assembly 1872 in combination with a diffractive element 1873, wherein the diffractive element of the imaging module diffracts laser light from the laser diode assembly to project a two-dimensional aiming pattern onto a substrate, s. Imaging module 1802A also includes support assembly 1810 including lens holder 1812, which holds lens barrel 1814 that carries imaging lens 212 that focuses images onto an active surface of image sensor array 182. Lens 212 may be e.g., a single lens (a lens singlet), a lens doublet or a lens triplet. Light sources 160 a, 160 b are aiming illumination light sources whereas light sources 160 c through 160 t are illumination light sources. Referring to FIG. 8 d, illumination light sources 160 c through 160 t project a two-dimensional illumination pattern 1830 over a substrate, s, that carries a decodable indicia such as a bar code symbol 1835 whereas aiming illumination light sources 160 a, 160 b project an aiming pattern 1838. In the embodiments shown and described in connection with FIGS. 8 a-8 c, light from aiming illumination light sources 160 a, 160 b is shaped by slit apertures 1840 in combination with lenses 1842 which image slits 1840 onto substrate, s, to form aiming pattern 1838 which in the embodiment of FIGS. 8 a-8 c is a line pattern 1838. Illumination pattern 1830 substantially corresponds to a full frame field of view of image reader 100 designated by box 1850. The present field of view of optical reader 100 is herein referred to as the “target” of optical reader 100. Aiming pattern 1838 is in the form of a line that extends horizontally across a center of field of view of image reader 100. Illumination pattern 1830 may be projected when all of illumination light sources 160 c through 160 t are operated simultaneously. Illumination pattern 1830 may also be projected when a subset of light sources 160 c through 160 t are simultaneously energized. Illumination pattern 1830 may also be projected when only one of light sources 160 c through 160 t is energized such as LED 160 s or LED 160 t. LEDs 160 s and 160 t of imaging module 1802 have a wider projection angle than LEDs 160 c through 160 t. In an optical reader 100 incorporating imaging module 1802, 1802 A illumination assembly 104 includes LEDs 160 a, 160 b, LEDs 160 c through 160 t and slit apertures 1840 in combination with lenses 1842.
A reader imaging module may be incorporated into one of a hand held housing as shown in FIGS. 9 a, 9 b and 9 c. In the embodiment of FIG. 9 a, hand held housing 101 is a gun style housing. In the embodiment of FIG. 9 b, hand held housing 101 supporting imaging module 1802 is in the form factor of a portable data terminal (PDT). In the embodiment of FIG. 9 c, hand held housing 101 supporting imaging module is in the form factor of a mobile telephone, often referred to as a “cell phone.” When optical reader 100 is a cell phone, optical reader 100 is configured to send voice data over GSM/GPRS transceiver 571 to GSM/GPRS network 198 (FIG. 10) and to receive over GSM/GPRS transceiver 571 voice data from GSM/GPRS network 198. Further, where optical reader 100 is a cell phone, optical reader 100 may be configured so that an operator inputs telephone numbers via keyboard 508. The specific imaging module 1802A described in connection with FIGS. 8 a-8 c may be incorporated in the optical reader shown in FIG. 9 a or the optical reader 100 shown in FIG. 9 b or the optical reader 100 shown in FIG. 9 c. However, in the embodiment shown in FIG. 9 a, housing 101 supports and encapsulates imaging module 1802B an imaging module of construction similar to imaging module 1802A, except that only two light sources 160 are incorporated into the imaging module. Housing 101 of the reader of FIG. 9 b supports imaging module 1802 which is generically labeled element 1802 to indicate that any one of the specific imager modules described herein, e.g., 1802, 1802A, 1802B, 1802D, 1802E may be incorporated into an optical reader according to the invention.
Referring to further aspects of optical reader 100, optical reader 100 may incorporate a graphical user interface (GUI) 3170 enabling selection between various operating modes. With GUI 3170 an operator moves pointer 3172 to a selected icon and clicks on the icon to configure optical reader 100 in accordance with an operating mode associated with the selected icon. Reader 100 may include pointer mover 512 (otherwise termed a navigation matrix) to facilitate movement of the pointer 3172. Buttons 512B of pointer mover 512 facilitate selection of an icon of a GUI interface that is supported by incorporating a multitasking operating system (OS) into reader 100 such as WINDOWS CE. GUI 3172 may be developed using various open standard languages as HTML/Java or XML/Java.
In the embodiment of FIG. 9 b, GUI 3170 includes a plurality of virtual selection buttons 3152, 3154, 3156, 3158, 3162, 3164. Selection of rolling shutter icon 3152 configures reader 100 so that during a next exposure period image sensor array 182 is operated in a rolling shutter mode. Selection of global shutter icon 3154 configures optical reader 100 so that during a next exposure period image sensor array 182 is operated in a global electronic shutter mode.
Selection of decode icon 3162 drives optical reader 100 into an indicia decode mode so that a next time a trigger signal is received, optical reader 100 captures a frame of image data and attempts to decode a bar code symbol or other decodable indicia (e.g., an OCR character) represented therein and outputs a decoded out message to display 504, or a spaced apart device 150, as is described with reference to FIG. 10. Selection of image capture (which may otherwise be referred to a picture taking) icon 3164 configures optical reader 100 so that next time a trigger signal is received, optical reader 100 captures image data and outputs the image data to one or more of a display 504, a specified memory address, or to a spaced apart device 150 without attempting to decode decodable indicia therein. Optical reader 100 may also be constructed so that optical reader 100 can be configured in accordance with a selected operating mode by sending to reader 100 a serial command from a spaced apart device, or by the reading of a specially configured programming bar code symbol.
Optical reader 100 is configured so that optical reader 100 receives a trigger signal when manual trigger 216 is manually depressed by an operator. Optical reader 100 may also be configured so that a trigger signal is received by the sensing of an object in the proximity of reader 100 or by the sending of a serial trigger command to reader 100 from a spaced apart device, 150, as shown in FIG. 10.
A flow diagram illustrating operation of optical reader 100 in one embodiment is described with reference to FIGS. 14 a, 14 b, and 14 c. At step 1100 an operator selects between an indicia decode mode and a picture taking mode. At step 1100 an operator may select icon 3162 (FIG. 9 b) to drive optical reader 100 into an indicia decode mode, or alternatively icon 3164 to drive optical reader 100 into a digital picture taking mode of operation. These modes may also be selected by sending to reader 100 a serial command from a spaced apart device 150 or by the reading of a programming bar code symbol. If an indicia decode mode of operation is selected, optical reader 100 executes an indicia decode process 1102. If a picture taking mode is selected, optical reader 100 executes picture taking process 1400.
An example of an indicia decode process 1200 is described with reference to FIG. 14 b. At step 1202 a trigger signal is received by one of the methods described (depressing trigger 216, object sensing, serial trigger command) to commence a decode process. At step 1203, control circuit 552 of optical reader 100 captures a plurality of “parameter determination” or test frames of image data. The frames of image data captured at step 1203 are not subject to indicia decode processing, but rather, are processed for parameter determination (e.g., exposure, gain, illumination). Alternatively, parameter determining step 1203 may be avoided. For example, control circuit 552 may apply parameters determined from a previous image capture operation rather than determining parameters at step 1203. At step 1204 control circuit 552 obtains a decode frame of image data details of which are explained herein.
For the capturing of frames of image data (i.e., “test” frames and/or frames for use in decoding, picture taking or other processing or storage) control circuit 552 (FIG. 1 a) may send an illumination control signal to illumination assembly 104 and various image capture initiation control signals to control/timing circuit 1092 of image sensor chip 1082 (labeled generically to refer to any of the image sensor chips described herein).
Image capture initiation control signals are described in greater detail with reference to FIGS. 15 a-15 e. For the capturing of image data, control circuit 552 may send to illumination assembly 104 an illumination control timing pulse 350 to energize at least one light source 160 such that illumination pattern 1830 is projected (as shown in FIG. 8 d). Control circuit 552 may also send to image sensor IC chip 1082 an exposure control timing pulse 354 and a read out control timing pulse 368, and a reset control timing pulse 370 (that is, control circuit 552 sends appropriate signals to image sensor IC chip 1082 to initiate exposure control timing pulse 354, read out control timing pulse 368 and reset control timing pulse 370).
In one embodiment as shown in FIG. 15 a, the exposure control timing pulse 354 begins after and finishes before the illumination control timing pulse 350. The read out control timing pulse 368 begins at the conclusion of the illumination control timing pulse 350. In another embodiment as shown in FIG. 15 b, the illumination control timing pulse 350′ begins after and finishes before the exposure control timing pulse 354′. In this embodiment, the read out control timing pulse 368′ begins at the conclusion of the exposure control timing pulse 354′. In further embodiments the exposure control timing pulse and the illumination control timing pulse overlap each other while occurring sequentially. In one such embodiment as shown in FIG. 15 c, this sequential operation can include the illumination control timing pulse 350″ starting, the exposure control timing pulse 354″ starting, the illumination control timing signal pulse 350″ ending, and then the exposure control timing pulse 354″ ending. In this embodiment, the read out control timing pulse 368″ begins at the conclusion of the exposure control timing pulse 354″. In a further such embodiment as shown in FIG. 15 d, the sequential operation can include the exposure control timing pulse 354″′ starting, the illumination control timing pulse 350″′ starting, the exposure control timing pulse 354″′ ending, and then the illumination control timing signal pulse 350″′ ending. In this embodiment, the read out control timing pulse 368″′ begins at the conclusion of the illumination control timing signal pulse 350″′. Each illumination control timing pulse 350, 350′, 350″, 350″′ described herein may comprise a plurality of short duration individual pulses, sometimes referred to as a “strobed” pulse, as is indicated by FIG. 15 e.
When exposure control timing pulse 354 is received by an image sensor IC chip and optical reader 100 is configured in a global electronic shutter operating mode, pixels from several rows of image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H are simultaneously exposed to light for the duration of the pulse. That is, when optical reader 100 is configured in an global electronic shutter operating mode, each of several rows of image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H that are subject to image data read out have common exposure periods such that the exposure period for each row of pixels the image sensor array subject to image data read out begins at a common exposure start time and ends at a common exposure stop time. The exposure period for each row of pixels image sensor array 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H subject to image data read out begins at the leading edge of exposure control timing pulse 354, 354′, 354″, 354″′ and ends at the falling edge of exposure control timing pulse 354, 354′, 354″, 354″′.
When read out control timing pulse 368 is received by image sensor IC chip 1082B, image data is read out from the image sensor array. Image signals corresponding to pixels of the image sensor array are converted into digital form by analog-to-digital converter 1086 and transferred into memory 560 by FPGA 580.
Optical reader 100 may be configured so that at step 1204 when reading out image data, optical reader 100 reads a “windowed frame” of image data. As indicated herein, a windowed frame of image data may be read out by selectively addressing pixels of a desired region of interest or window. A windowed frame of image data read out during frame capture at step 1204 may comprise pixel values corresponding to all or substantially all monochrome pixels 250M of an image sensor array. With further reference to the timing diagrams of FIGS. 15 a, 15 b, 15 c and 15 d, a reset control timing pulse 370 for resetting pixels that are not selectively addressed may be coordinated with the exposure control timing pulse 354 for controlling exposure of pixels that are selectively addressed for reading out a windowed frame of image data. Thus, for reading out a monochrome frame of image data from a hybrid monochrome and color image sensor array, e.g., image sensor array 182A or image sensor array 182B, reset control timing pulse 3709 is applied to reset color pixels of the image sensor array 182 while exposure control timing pulse 354 is applied to enable exposure of monochrome pixels of the image sensor array. To facilitate resetting of color pixels of an image sensor array independent of resetting of monochrome pixels, an image sensor array may be configured to include a reset control line grid specifically adapted to enable resetting of color pixels. Applying reset control pulse 370 to drive color pixels into reset while monochrome pixels are being exposed to light can be expected to eliminate electron diffusion cross talk and to reduce cross talk resulting from light rays angularly entering the color pixels during exposure.
When frames are obtained at step 1204, they are obtained in a form suitable to facilitate indicia decoding such as bar code symbol decoding or OCR decoding. With the windowed frame of image data read out at step 1204 from a hybrid monochrome and color image sensor array 182A, 182B including only image data corresponding to monochrome pixels and no image data corresponding to color sensitive pixels 250C, control circuit 552 at step 1204 may store gray scale values into RAM 560, each pixel value representing an intensity of light at a particular monochrome pixel of image sensor array 182A, 182B. The frame of image data obtained at step 1204 may include e.g., 8 bit gray scale pixel values, 10 bit gray scale pixel values or 12 bit gray scale pixel values. Since numerous legacy bar code decoding and OCR decoding schemes are designed to operate on monochrome gray scale image data or binarized image data derived from gray scale image data, the selective addressing of monochrome pixels 250M in the capturing of a monochrome image frame yields a frame that is well suited for being subjected to indicia decoding processing. Of course, in certain applications, control circuit 552 at step 1204 may obtain a decode frame of image data including color image data. For example, where decode circuit 1702 is configured to decode color encoded bar code symbols, it is advantageous for control circuit 552 to obtain a decode frame of image data including color image data at step 1204.
In the execution of step 1204, control circuit 552 may carry out a plurality of alternative processes in obtaining a decode frame of image data. Referring to the flow diagram of FIG. 14 d, optical reader 100 at step 1204 may simply capture a single windowed frame of image data which has been described herein above. As indicated by process step 1205 of FIG. 14 d, control circuit 552 may carry out process step 1204 by selectively addressing monochrome pixels 250M of a hybrid monochrome and color image sensor array such as image sensor array 182A or image sensor array 182B and reading out image data from monochrome pixels 250M only; i.e., a windowed frame of image data comprising image data from monochrome pixels 250M only.
Referring to the flow diagram of FIG. 14 e, the obtaining a decode frame step 1204 may be carried out in the alternative by the execution of steps 1206 and 1207. At step 1206 optical reader 100 may generate a frame of image data that includes image data corresponding to monochrome pixels 250M and color sensitive pixels 250C and at step 1207 image sensor array 182A, 182B may convert pixel values of the frame generated at step 1206 into gray scale values. The frame generated at step 1206 may be generated by exposing color and monochrome pixels of image sensor array 182A, 182B during a single exposure period, and reading out image data from both color and monochrome pixels 250M, 250C of image sensor array 182A, 182B during a single pixel read out period. Alternatively, at step 1206 control circuit 552 of optical reader 100 may combine image data from two different frames such as two successive frames, wherein a first of the captured frame is a windowed frame of image data including image data from color sensitive pixels 250C only and a second of the frames is a frame of image data including image data read out from monochrome pixels 250M only.
Referring to the flow diagram of FIG. 14 f, optical reader 100 may also obtain a decode frame at step 1204 by carrying out steps 1208 and step 1209. At step 1208 optical reader 100 may capture a windowed frame of image data including image data corresponding to monochrome pixels 250M only and at step 1209 control circuit 552 may interpolate pixel values corresponding to color pixel positions of image sensor array 182A, 182B utilizing the monochrome pixel values from the windowed monochrome frame captured at step 1208. For example, control circuit 552 may capture a gray scale pixel value frame 5202 as illustrated in FIG. 16 a that includes a gray scale pixel value for each monochrome pixel position of the image sensor array 182A, 182B. Optical reader 100 may interpolate a monochrome pixel value for any “missing pixel” color pixel position of the frame 5202. Referring to frame 5202, frame 5202 is a gray scale frame of image data captured by selecting reading out image data from an image sensor array 182B constructed in accordance with FIGS. 4 a-7 b (Period=2).
Pixel positions P₁₁, P₃₁, P₅₁, P₁₂, P₂₂, P₃₂, P₄₂, P₅₂, P₁₃, P₃₃, P₆₃. . . are pixel positions corresponding to monochrome pixels 250M of image sensor array 182 for which individual frame image data has been read out. Pixel positions P₂₁, P₄₁, P₂₃, P₄₃, . . . are missing pixel positions corresponding to color sensitive pixels, 250C of image sensor array 182B. Referring to the frame of image data represented at FIG. 16 a an optical reader 100 may calculate a gray scale pixel value for color pixel positions, e.g., position P₂₃, by averaging the gray scale values for each pixel position that is adjacent to pixel position P₂₃and each pixel position that is corner adjacent to color pixel position P₂₃. For example, referring to the frame represented in FIG. 16 a, a gray scale value for color pixel position P₂₃can be interpolated by averaging pixel values of pixel positions P₁₂, P₂₂, P₃₂, P₁₃, P₃₃, P₁₄, P₂₄, P₃₄. A pixel value for “missing pixel” position P₂₃can also be interpolated utilizing more than 8 neighboring pixel positions. Also, corner adjacent pixels may be weighted less than side, top or bottom adjacent pixels during averaging. In one simple averaging method, only four surrounding pixels are averaged; namely, the top and bottom adjacent pixels and the two side adjacent pixels adjacent to the pixel position for which a gray scale value is being interpolated. In a still further interpolation method, only two pixels are used for averaging; namely either the two side adjacent pixels adjacent to the pixel position being interpolated or the top and bottom adjacent pixels. A two-dimensional image representation of a linear bar code symbol can be expected to have several consecutive pixel positions along a column with similar gray scale values, if the representation of the symbol is oriented with 0° or 180° angle of rotation (i.e., the symbol is right side up or upside down). If the symbol representation has a 90° or 280° angle of rotation, several consecutive pixel positions along rows of pixel positions can be expected to have similar valued gray scale values. Accordingly, it can be seen that interpolating pixel values of adjacent pixel position values running in the direction of bars in a symbol representation yields truer edge information than utilizing all surrounding pixel positions for interpolation.
In one method of the invention, the correlation between a pair of horizontally oriented scan lines is calculated along with a correlation between a pair of vertically oriented scan lines. The two correlation measurements are then compared. If row scan lines are more closely correlated, column adjacent pixels are selected for interpolation. If column scan lines are more closely correlated, row adjacent pixels are selected for interpolation. An exemplary set of code for calculating a first derivative correlation for a pair of scan lines (horizontal or vertical) is presented by Table 1.

TABLE 1

	Exemplary Code For Performing First Derivative Correlation Calculation

	%OneDcorelate: correlates two 1D 1st derivative signals to report the %correlation
	%input a,b: 1D array
	%output c: 1st derivative correlation
	function c=OneDcorrelate(a,b)
	% “diff” is the first derivative calculation.
	%for an input array a=[a_i]ⁿ _i=1 then diff(a) =[a_i− a_i+1]ⁿ⁻¹ _i=1
	da=diff(double(a));
	db=diff(double(b));
	n=length(da);
	c=0;
	for i=1:n
	c=c+da(i)*db(i);
	end
	[End Table 1]

A set of code for interpolating missing color pixel position values by one of three methods (simple averaging, first derivative correlation, and simple correlations) wherein “M-set” refers to the monochrome set of pixels is presented in Table 2.

TABLE 2

Exemplary Code For Interpolating Missing Pixels Corresponding To Color Pixel Positions

% MsetInterpolation: interpolates missing M-set pixels

%input I_Mset: M-set image

%input method: 1:first derivative correlation; 2: simple correlation; 3:

%simple averaging

%input p: sample period

%output Im: interpolated monochrome image

function Im=MsetInterpolation(I_Mset,method,p)

Isz=size(I_Mset);

%M-set topology

% {circumflex over ( )}

% MMMMMMMMM

% MxMxMxMxM

% MMMMMMMMM

% MxMxMxMxM

%(MMMMMMMMM)

% v

Im=double(I_Mset);

m=Isz(1);

n=Isz(2);

%correlated averaging

for i=p:p:m

for j=p:p:n

if i+1 <=m & j+1 <=n

if method == 2

%simple correlation

if abs(Im(i−1,j)−Im(i+1,j)) < abs(Im(i,j−1)−Im(i,j+1))

Im(i,j)=(Im(i−1,j)+Im(i+1,j))/2;

else

Im(i,j)=(Im(i,j−1)+Im(i,j+1))/2;

end

else if method==1

%first derivative correlation

if OneDcorrelate(Im(i−1,j−1:j+1),Im(i+1,j−1 :j+1)) > OneDcorrelate(Im(i−1:i+1,j−

1),Im(i−1:i+1,j+1))

Im(i,j)=(Im(i−1,j)+Im(i+1,j))/2;

else

Im(i,j)=(Im(i,j−1)+Im(i,j+1))/2;

end

else %method==3

%simple averaging

Im(i,j)=(Im(i−1,j)+Im(i+1,j)+Im(i,j−1)+Im(i,j+1))/4;

end

else if i+1 <=m & j+1 > n

Im(i,j)=(Im(i−1,j)+Im(i+1,j))/2;

else if i+1 > m & j+1 <=n

Im(i,j)=(Im(i,j−1)+Im(i,j+1))/2;

else if i+1 > m & j+1 > n

Im(i,j)=(Im(i−1,j)+Im(i,j−1))/2;

end

Im=uint8(Im);

[End Table 2]

At step 1210, optical reader 100 transfers the frame of image data obtained at step 1204, to an indicia decode circuit 1702 which may be a bar code symbol decoding circuit or autodiscrimination circuit 1704 including an indicia decode circuit 1702. In one embodiment, decode circuit 1702 decodes 1D and 2D bar code symbols and OCR characters. Autodiscrimination circuit 1704 may decode 1D and 2D bar code symbols and OCR characters (decodable indicia) and automatically discriminate between decodable indicia and handwritten characters. In the event that autodiscrimination circuit 1704 recognizes the presence of handwritten character information, autodiscrimination circuit 1704 automatically outputs to display 504 and/or a spaced apart device 150 image data representing the handwritten character image data. Further details of indicia decode circuit 1702 and autodiscrimination circuit 1704 are described in copending U.S. patent application Ser. No. 11/077,975, filed Mar. 11, 2005, incorporated by reference and U.S. application Ser. No. 10/958,779, filed Oct. 5, 2004, also incorporated herein by reference.
In general, indicia decoding accuracy is expected to increase with an increase in the percentage of monochrome pixels of image sensor array 182A, 182B. With image sensor array 182B having a period of P=2, every other row of pixels of image sensor array 182B are all monochrome pixels. Thus, horizontal scan lines can be launched through horizontal rows of pixel values of a frame of image data obtained utilizing a P=2 image sensor array 182B during attempts to decode a linear bar code symbol without substantial reduction in performance relative to a frame obtained utilizing an all monochrome pixel image sensor array. For decoding linear bar code symbols, control circuit 552 may read image data along scan lines, such as scan lines defined by a horizontal row of pixel positions to determine the relative widths of bars and spaces of a symbol and then decode the symbol through table lookup to determine a set of decoded character data corresponding to the bar space information.
At step 1212 control circuit 552 receives a decoded output message from decode circuit 1702 or autodiscrimination circuit 1704. The message received by control circuit 552 at step 1212 may be e.g., a decoded bar code message or a set of decoded OCR characters. At step 1214 optical reader 100 outputs a decoded out message. At step 1214 control circuit 552 may send decoded out bar code data and/or decoded OCR data to display 504 or to a spaced apart device 150 or to a data storage memory location of reader 100, or system 145 as described in FIG. 10.
Examples of spaced apart devices 150 which may be in communication with optical reader 100 are shown and described in connection with FIG. 10. Optical reader 100 may be part of a system 145 and may be included in a local area network (LAN) 170 which comprises, in addition to reader 100, such spaced apart devices as other portable readers 100′, 100″, network access point 174, personal computers 172 and central server 176 that are spaced apart from hand held housing 101 of reader 100, all of which are connected together via backbone 177. Server 176 in turn is in communication with a variety of additional spaced apart devices 150 that are spaced apart from hand held housing 101 of reader 100 and which through server 176 are in communication with optical reader 100. Server 176 may be connected via gateways 179, 180 and network 181 to a first distant remote local area network 185 located miles to thousands of miles away from local area network 170 and a second distant local area network 2170 also located miles to thousands of miles away from local area network. Network 170 may be located at a supplier's warehouse. Network 2170 may be located at a delivery destination; and network 185 may be located at a data processing/data archiving facility. Network 185 can be configured to assemble, store and maintain in server 184 various web pages accessible with use of optical reader 100, that summarize data that has been collected by various optical readers 100, 100′, 100″, 100R. Server 176 may alternatively or redundantly be connected to remote network 185 via private communication line 190. IP network 181 may be the Internet or a virtual private network (VPN). Remote LAN 185 may include a personal computer 186 and a remote server 184 connected via backbone 191. Remote LAN 185 may also include a wireless communication access point 193. Remote LAN 185 may also include a personal data assistant (PDA) 189. Remote LAN 2170 may include a server 2176, connected to IP network 181 via gateway 2179, backbone 2177, access point 2174, PC 2172, and optical reader 100, 100R. System 145 may be configured so that a display equipped device, e.g., device 100′, 172, 186, 189 automatically displays data, such as decoded out bar code message data of a visual display color image frame of image data, received from optical reader 100 on its associated display 1504 when receiving that data.
All of the steps of process 1200 are carried out automatically in response to the receipt of a trigger signal. The steps of process 1200 continue automatically until a stop condition is satisfied. A stop condition may be e.g., the receipt of a trigger stop signal as may be generated by release of trigger 216 or the successful decoding of a predetermined number of bar code symbols. As indicated by return line 1211 of FIG. 14 b, control circuit 552 may repeatedly attempt to obtain image data and attempt to decode decodable indicia therein until a stop condition is satisfied.
Interpolating monochrome pixel values for “missing pixels” pixel positions is particularly advantageous where a hybrid monochrome and color image sensor array according to the invention includes a high number of color sensitive pixels distributed at spaced apart pixel positions throughout image sensor array. In other instances as alluded to previously in connection with the flow diagram of FIG. 14 b, control circuit 552 may obtain a decode frame of image data at step 1204 that is suitable for transferring to decode circuit 1702 by simply reading from an image sensor array image data from monochrome pixels 250M without interpolation of any pixel values at “missing pixel” pixel positions where an image sensor array of reader 100 is constructed in accordance with image sensor array 182A, and monochrome pixels 250M form a complete checkerboard pattern, (there are no “missing” monochrome pixels positions in the M×N matrix of monochrome pixels within image sensor array 182A). Accordingly, where optical reader 100 includes image sensor 182A, the decode frame of image data at step 1204 is advantageously obtained by reading out from image sensor array 182A image data from monochrome pixels 250M without interpolation of any further monochrome pixel values.
It may also be useful to obtain a decode frame of image data at step 1204 without interpolation of monochrome pixel values where optical reader 100 includes a linear bar code symbol optimized image sensor array 182B of one of the versions described in connection with FIGS. 5 g-5 j. In the versions of image sensor array 182B shown and described in connection with FIGS. 5 g-5 j, image sensor array 182B includes at least one “zone” of monochrome pixels 2500M and at least one “zone” of color sensitive pixels 2500C. Monochrome zone of pixels 2500M of a linear symbol decoding optimized version of image sensor array 182B generally comprises an elongated line of monochrome of pixels 250M having a minor dimension of one to a limited number of rows of pixels (which may be diagonal rows). Where optical reader 100 includes a linear symbol optimized version of image sensor array 182B a reduced area decode frame of image data at step 1204 without any “missing pixel” pixel positions can be obtained by selectively addressing pixels of monochrome zone 2500M and selectively reading out of image data from the pixels of monochrome zone 2500M without reading any image data from the pixels of color sensitive zone of pixels 2500C. More specifically, where optical reader 100 comprises a linear symbol optimized version of image sensor array 182B, control circuit 552 at step 1204 may obtain a reduced area monochrome frame of image data at step 1204 (FIG. 14 b) and then transfer the reduced area monochrome frame of image data to decode circuit 1702 at step 1210. A reduced area frame of image data is further explained with reference to FIG. 11 illustrating an application where an optical reader 100 is utilized to collect decoded bar code data and image data from a parcel 1260 carrying various bar code symbols, e.g., linear bar code symbol 1266 and two-dimensional bar code symbol 1270. A full area frame of image data that may be obtained by optical reader 100 represents the scene area indicated by rectangular border 1276 of FIG. 11. Where image data from all pixels of image sensor array 182B are read out, a full area frame of image data is obtained. When optical reader 100 obtains a reduced area frame of image data, a reduced area frame of image data representing the reduced scene area as indicated by dashed-in border 1278 may be obtained. In the example of FIG. 11, optical reader 100 may incorporate one of the linear symbol optimized image sensor arrays 182B as shown in FIGS. 5 g and 5 h. A reduced area frame of image data representing the reduced scene area 1278 may be obtained by reading out image data from monochrome zone of thin center line monochrome zone 2500M of image sensor array 182B according to one of the versions of FIGS. 5 g and 5 h. It is seen with reference to FIG. 11 that when optical reader 100 obtains a reduced area frame of image data at step 1204 representing the reduced scene area 1278, the reduced area frame of image data, though reduced, can be of sufficient size to include a representation of linear bar code symbol 1266 carried by parcel 1260. Imaging module 1802 such as module 1802A (FIG. 8 a) of reader 100 can be constructed so that aiming pattern 1838 (FIG. 8 d) is projected onto scene area 1278 at expected reading angles, while aiming light sources 160 a, 160 b, and remaining light sources 160 c-160 t are energized simultaneously during the time that pixels of zone 2500M are exposed for read out of image data from zone 2500M. Simultaneously projecting aiming pattern 1838 and illumination pattern 1830 onto scene area 1278 improves the signal strength of image data corresponding to pixels of zone 2500M. After receiving the thin line reduced area frame of image data at step 1210, decode circuit 1702 may process the thin line reduced area decode frame of image data to decode linear bar code symbol 1266 by calculating the bar space widths of the bars and spaces of linear bar code symbol 1266 and then determining the characters of the symbol through table lookup. In a further aspect, optical reader 100 may be configured so that aiming pattern 1838 (FIG. 8 d) is projected horizontally at a center of a field of view 1276 of optical reader 100 to coincide with area 1278 represented by the reduced area image obtained at step 1204 to aid an operator in obtaining an image that includes a representation of linear bar code symbol 1266. The frame rate of optical reader 100 when obtaining the reduced area decode frame of image data at step 1204 may be significantly reduced relative to the frame rate of optical reader 100 when obtaining a full frame of image data. Accordingly, a method of the invention where optical reader 100 at step 1204 obtains a reduced area frame of image data which is transferred to decode circuit 1702 is optimized for fast (“snappy”) decoding. As has been described herein, color sensitive pixels 250C may be set to reset while monochrome pixels 250M are exposed for selective read out of image data from monochrome pixels 250M.
With further reference to the application view of FIG. 11, it is seen that the reduced area frame of image data representing scene area 1278 may not include a complete representation of linear bar code symbol 1266 and it is further seen that parcel 1260 may include or carry additional bar code symbols such as two-dimensional bar code symbol 1270 that is part of postal area 1268 of parcel 1260. According to the invention in another aspect, optical reader 100 can be configured so that where indicia decode circuit 1702 cannot successfully decode a bar code symbol via processing of a reduced area frame of image data or where control circuit 552 is programmed to search and decode multiple bar code symbols, control circuit 552 executes return line (FIG. 14 b) to re-execute the obtaining of a decode frame of image data at step 1204. However, when control circuit 552 executes step 1204 the second time, control circuit 552 captures a frame of image data that represents a scene area that is larger than the scene area represented by the frame obtained during the first execution of step 1204. The decode frame of image data obtained by a second execution of step 1204 may be a full area image data frame representing the full field of view of optical reader 100 indicated by dashed-in border 1276 of FIG. 11. Where color zones 2500C of image sensor array 182B are distributed in a Bayer pattern, control circuit 552 during the second execution of obtain step 1204 may selectively read out image data from the green pixels of color sensitive zones of image sensor array of 2500C and interpolate green pixels values at non-green pixel positions utilizing the green pixel values so that the decode frame of image data obtained at step 1204 includes all green pixel values. Further, the missing pixel positions corresponding to monochrome zone 2500M can be filled in utilizing the image data obtained during the previous execution of step 1204 as scaled based on a relationship between the color scale values of pixels corresponding to zone 2500M and the color scale values of pixels surrounding zone 2500M. At step 1210, larger area green image data is transferred to indicia decode circuit 1702. Indicia decode circuit 1702 may attempt to decode linear bar code symbol 1266 and all other bar code symbols such as two-dimensional bar code symbol 1270 that may be represented in the image obtained during the second execution of step 1204. With reference to the application view of FIG. 11, optical reader 100 incorporating a linear symbol decode optimized to image sensor array 182B may attempt to decode linear symbol 1266 utilizing small area image representing area 1278 and then subsequently attempt to decode a two-dimensional bar code symbol, e.g., symbol 1270, utilizing a larger area frame of image data representing scene area 1276. It will be seen that the method described where control circuit 552 obtains a reduced area frame of image data, attempts to decode, then subsequently obtains a larger frame of image data and attempts to decode utilizing the larger image may be practiced utilizing an “all monochrome” image sensor array 182F as shown and described in connection with FIG. 17 b. Where optical reader 100 incorporates an all monochrome image sensor array 182F as shown in FIG. 17 b, it is particularly useful to set monochrome pixels 250M to reset that are not being selected for read out of a reduced area decode frame of image data at step 1204 during exposure periods for selected monochrome pixels 250M that are being selectively addressed for image data read out.
Monochrome pixels 250M transmit more light than color sensitive pixels 250C. Therefore, resetting monochrome pixels 250M that are not selectively addressed and which are adjacent to a region of interest during an exposure period can be expected to have a greater benefit in terms of improving the overall signal to noise ratio of reader 100 than resetting color sensitive pixels 250C that are adjacent to a region of interest during an exposure period.
With still further reference to the application view of FIG. 11, it may be advantageous to utilize optical reader 100 to obtain a visual display color frame of image data representing parcel 1260. For example, parcel 1260 may include a damaged area 1272. Obtaining a visual display color frame of image data corresponding to parcel 1260 creates a record documenting parcel damage. Referring to the application view of FIG. 12 a, different optical readers 100 and 100R at different locations A and B located miles apart along a delivery route may be utilized to document physical transformations of parcel 1260 when parcel 1260 is carried along a delivery route. Optical reader 100 at location A including LAN 170 (FIG. 10) may be operated to obtain a visual display color frame of image data of parcel 1260 when parcel 1260 is located at location A. Further, the color frame may automatically be transferred to remote server 184 (FIG. 10) having a database 187 of color frames of image data that are indexed by a parcel identifier decoded in a parcel bar code symbol 1266 which identifier is also transmitted to remote server 184 automatically when optical reader 100 reads bar code symbol 1266. At location B remote optical reader 100, 100R (FIG. 10) may be utilized to again decode bar code symbol 1266 and capture visual display color frame of image data representing parcel 1266 and automatically transfer the parcel identifier corresponding to bar code 1266 and the color frame of image data to remote server 184. With reference to the application view of FIG. 12 a the color frame of image data transmitted to remote server 184 from location B will include a representation of damaged area 1272 that is not included in the color frame of image data transmitted to remote server 184 from location A. Accordingly, a person (for example, at PC 172 viewing web pages of server 184) reviewing the parcel identifier indexed color frame data of database 187 can determine that the damage to parcel 1260 occurred during the time that the parcel was delivered from location A to location B. Referring to FIG. 12 b, optical reader 100 can also be utilized to take color pictures of a delivery vehicle 1282 that carried parcel 1260 from location A to location B. In the example of FIG. 12 b, a picture being taken by optical reader 100 has the field of view indicated by rectangle 1286. The field of view encompasses parcel 1260, and delivery vehicle 1282, including a license plate 1284. Trigger 216 can be actuated a first time to decode bar code symbols 1266, 1267 and then an additional time or times to have a picture of parcel 1260 and/or vehicle 1272 including a picture of license plate 1284. The decoded bar code data and multiple color frames of image data may be associated with one another into a single transaction data set, and then via a packet based transmission scheme, the transaction data set may be sent to remote server 184, which may organize the data into viewable web pages viewable at PC 172. Optical reader 100, which may be incorporated in hand held housing 101, can be configured so that all of the data of the transaction data set is sent to remote server 184 in response to a single command input to optical reader 100 via a user interface of reader 100 (e.g., 3170). Further aspects of optical reader 100 operating in a picture taking mode of operation are described with reference to the flow diagrams of FIGS. 14 c, 14 g and 14 h.
Referring again to the flow diagram of FIG. 14 a, a digital picture taking process 1400 is executed when optical reader 100 is configured to operate in a picture taking mode of operation. At step 1100, a picture taking mode of operation may be selected, e.g., by clicking on “image capture” icon 3164 (FIG. 9 b) and at step 1104 picture taking process 1400 is executed.
Referring to the steps of picture taking process 1400, optical reader 100 at step 1402 receives a trigger signal as may be generated e.g., by depression of a manual trigger an object in the proximity of reader 100 being sensed or receipt of a serial command. At step 1403 control circuit 552 captures a plurality of “test” or parameter determination frames of image data. The frames of image data captured at step 1403 are not output for visual display; but rather are processed in order to determine operational parameters (exposure setting, gain illumination). Alternatively, step 1404 can be avoided and control circuit 552 can instead load operational parameters that were derived during a past image capture operation. At step 1404 control circuit 552 obtains a “visual display” image frame of image data. A visual display color frame of image data is one that is generated for visual display on a display and may include three color scale values for each pixel position of the plurality of pixel positions of the frame. A visual display frame after being obtained is sent to a display for visual display of an image or to a memory location for future display. In the embodiment of FIG. 14 c, the image data obtained at step 1404 is not transferred to decode circuit 1702.
An image captured as part of obtaining at step 1404 may be one that is captured in accordance with the timing diagrams of FIGS. 15 a-15 e. In an alternative embodiment, the control signals input into image sensor IC chip 1082 for the capture of a frame of image data may not include illumination control timing pulse e.g., pulse 350. In many applications an object subject to image capture by optical reader 100 during a picture taking mode will be a long range image (an object will be subject to image capture is one that is one to several feet from image reader). Light from light sources 160 may have little affect on an image captured that corresponds to a long range object; thus, optical reader 100, in one embodiment may not send an illumination control timing pulse at step 1404.
However, depending on the application, it may be desirable to increase the illumination intensity of optical reader 100 during capture of color image data relative to the intensity during capture of monochrome image data to compensate for the signal reduction affect of color filter elements 260R, 260G, 260B, 260M, 260C. In a further aspect, optical reader 100 can have a plurality of operator selectable configuration settings. Optical reader 100 can be configured so that activation of button 3150 toggles through a sequence of options one of which may be selected by actuation of a key of keyboard 508. As shown by Table 3, where e=exposure, g=gain, and i=illumination intensity, a selection of a configuration setting can result in a differentiation between the imaging parameters of reader 100 during read out of monochrome image data at step 1204 and the imaging parameters of reader 100 during read out of color image data at step 1404. Configuration setting 1 is a base line setting wherein there is no differentiation between monochrome read out and color image data read out imaging parameters. Configuration setting 2 has been described above. With configuration setting 2, there is no illumination during read out of color image data at step 1404. Configuration setting 3 has also been described above. With configuration setting 3, illumination intensity is increased for read out of color image data. With configuration setting 4, illumination intensity for read out of monochrome image data can be increased. For example, as described herein, illumination pattern 1830 and aiming pattern 1838 can be projected simultaneously during read out of monochrome image data corresponding to a monochrome zone 2500M of pixels. With configuration setting 5, exposure time is boosted for read out of color image data and with configuration setting 6, gain is boosted for read out of color image data. Configuration setting 3 is highly useful where optical reader 100 includes a long distance flash illumination light source 160, 160X or where optical reader 100 is used for picture taking at close range.

TABLE 3

	Imaging Parameters When	Imaging Parameters When
	Reading Out Monochrome	Reading Out Color Image
	Image Data At Decode Frame	Data At Visual Display
Configuration	Obtain Step 1204	Obtain Step 1404

1	e = e₀	e = e₀
	g = g₀	g = g₀
	i = i₀	i = i₀
2	e = e₀	e = e₀
	g = g₀	g = g₀
	i = i₀	i = 0
		(Illumination Off)
3	e = e₀	e = e₀
	g = g₀	g = g₀
	i = i₀	i = i₁, i₁> i₀
4	e = e₀	e = e₀
	g = g₀	g = g₀
	i = i₂, i₂> i₀	i = i₀
5	e = e₀	e = e₁, e₁> e₀
	g = g₀	g = g₀
	i = i₀	i = i₀
6	e = e₀	e = e₀
	g = g₀	g = g₁, g₁> g₀
	i = i₀	i = i₀

In executing the obtaining visual display color frame of image data step 1404, optical reader 100 may carry out a variety of alternative processes. With reference to the flow diagram of FIG. 14 g, a process is described wherein optical reader 100 may obtain a visual display color frame of image data utilizing image data read out from color sensitive pixels 250C only. With reference to the flow diagram of FIG. 14 h, a process is described wherein control circuit 552 obtains a visual display color frame of image data utilizing image data derived by reading out of image data from both monochrome pixels and color sensitive pixels of image sensor array 182.
Referring to the flow diagram of FIG. 14 g, control circuit 552 at step 1405 captures a windowed frame of image data by selectively addressing color pixels 250C and by selectively reading out image data from color pixels 250C of image sensor array 182A, 182B. As explained previously herein, image sensor array 182A, 182B may include a separate reset control grid for resetting monochrome pixels 250M independent of color sensitive pixels 250C. At step 1405 while color sensitive pixels are exposed for read out of image data, monochrome pixels 250M may be reset with use of a reset control timing pulse 370, 370′, 370″, 370″′ (FIGS. 15 a-15 d). Coordinating a reset control timing pulse 370, 370′, 370″, 370″′ for resetting monochrome pixels with an exposure control timing pulse 354, 354′, 354″, 354″′ for controlling exposure of color sensitive pixels 250, 250C reduces cross talk resulting from light rays entering monochrome pixels 250M, i.e., by eliminating electron diffusion cross talk and by reducing cross talk attributable to light rays angularly penetrating through monochrome 250M.
At step 1406, optical reader 100 automatically transfers the color filter array image data frame captured at step 1405 to a demosaicing circuit 1706 (FIG. 1 e). Taking as an input a color filter array image data frame, demosaicing circuit 1706 outputs a visual display color frame of image data. Where display 504 is a color display configured to receive red, green and blue (RGB) signals for each pixel of display 504, demosaicing circuit 1706 at step 1406 may generate RGB color scale values for each pixel of display 504 so that a frame output by demosaicing circuit 1706 is compatible with display 504. The color scale values may comprise e.g., 8 bits, 10 bits, or 12 bits of data. At step 1407, optical reader 100 receives a visual display color frame of image data from demosaicing circuit 1706.
A particular example of optical reader 100 executing step 1404 is described with reference to FIG. 16 b. At step 1406 where optical reader 100 includes a hybrid monochrome color image sensor array 182A, 182B including a Bayer pattern color filter array as shown in FIG. 2 c and FIG. 5 a, optical reader 100 may read out an RGB Bayer pattern frame of image data as shown in FIG. 16 b. Where a reader image sensor array is provided by image sensor array 182B including a 1280×1024, array of pixels, with a 320×256 subset array (P=4) of color sensitive pixels 250, 250C (P=4) dispersed in array 182B optical reader 100 at step 1405 captures a 320×256 Bayer pattern of pixels. Demosaicing circuit 170 processes the Bayer pattern frame 1502 as shown in FIG. 16 b to output a visual display color frame of image data including a 320×256 color image, wherein each pixel of the frame includes a red color scale value, a green color scale value, and a blue color scale value. In such an embodiment, demosaicing circuit 1706, for each pixel of the Bayer pattern color filter array image data frame 5204, interpolates red, green, and blue values. Referring to frame 5204 shown in FIG. 16 b, optical reader 100 determines a red value for red pixel position P₃₂simply by reading the color scale value of pixel position P₃₂. Optical reader 100 determines a green value for red pixel P₃₂by averaging the values of green pixel positions P₃₁, P₂₂, P₄₂and P₃₃. Optical reader 100 may interpolate a blue value for red pixel position P₃₂by averaging the values of blue pixel positions P₁₄P₄₁, P₂₃, P₄₃. It will be seen that red, green, and blue values can be determined for each pixel position interpolating the pixel values as necessary. With increased processing speeds, it is possible to utilize dozens or more surrounding pixel values for interpolation of a red, green, or blue pixel for each pixel position.
In another aspect of the invention, the accuracy with which color scale values for each pixel position may be interpolated can be enhanced by utilizing monochrome pixel values in the color scale value interpolation process. Referring to red pixel position P₃₂of frame 5204, it has been described that color scale values at green pixel positions P₃₁, P₂₂, P₄₂, P₃₃may be averaged for interpolating a green color scale value at pixel position P₃₂. In another method, monochrome pixel values at positions P₃₃, P₂₂, P₄₂, P₃₃may be utilized for enhancing the interpolation of a green pixel value at position P₃₂. The monochrome pixel values at positions P₃₃, P₂₂, P₄₂, P₃₃may be interpolated from monochrome pixel values by one of the monochrome pixel interpolation methods described herein. Then, the color scale value at each pixel position, P₃₂, P₂₂, P₄₂, P₃₃may be offset by a value, Delta, equal to the difference between the interpolated monochrome pixel values at the position being interpolated and the monochrome pixel value at the position contributing to the interpolation calculation. Thus, a green color scale value at position P₃₂may be calculated according to Eq. A.
$\begin{matrix} G (P_{32}) = \frac{\begin{matrix} [G (P_{31}) + {Delta}_{31}] + [G (P_{22}) + {Delta}_{22}] + \\ [G (P_{42}) + {Delta}_{42}] + [G (P_{33}) + {Delta}_{33}] \end{matrix}}{4} & (Eq . A) \end{matrix}$
Where Delta₃₁=M(P₃₂)−M(P₃₁), Delta₂₂=M(P₃₂)−M(P₂₂), Delta₄₂=M(P₃₂)−M(P₄₂), Delta₃₃=M(P₃₂−M(P₃₃).
Similarly, a blue color scale value at position P₄₂may be interpolated according to the formula of Equation B.
$\begin{matrix} B (P_{42}) = \frac{[B (P_{41}) + {Delta}_{41}] + [B (P_{43}) + {Delta}_{43}]}{2} & (Eq . B) \end{matrix}$

Where Delta₄₁=M(P₄₂)−M(P₄₁) and Delta₄₃=M(P₄₂)−M(P₄₃).

An exemplary algorithm for interpolating a color scale value at a color pixel position utilizing monochrome pixel values is presented in Table 4 where “C-set” refers to color pixel values and “M-set” refers to monochrome pixel values.

TABLE 4

Algorithm For Interpolating Color Scale Values Utilizing Monochrome Image Data

1)	For each color pixel C for interpolation, select the missing color neighborhood C-set
	pixel values Ci and select the corresponding neighborhood M-set pixel values Mi.
	Select corresponding M-set pixel value M to color pixel C.
2)	let C=0
3)	for i=1 to n where n is the number of neighborhood pixel Ci
4)	C=C+Ci+M−Mi
5)	end
6)	C=C/n

Regarding step 1, it is noted that there will normally be two neighborhood color or “C-set” pixels where blue or red values are interpolated at a green pixel position, and in other cases four neighborhood color pixels.
Another particular example of optical reader 100 executing steps 1405 and 1406 is explained with reference to FIG. 16 c. Where a reader image sensor array is provided by image sensor array 182B including 1280×1024 array of pixels, and a period P=4 of color sensitive pixels formed with a Cyan-Magenta (Cy-Mg, or “CM”) color filter array as shown in FIG. 5 b, optical reader 100 at step 1405 reads out a color filter array frame 5206 as shown in FIG. 16 c. Color filter array image data frame 5206 includes a 320×256 pattern of Cy-Mg pixel values. Demosaicing circuit 1706 may process image data frame 5206 into a visual display frame such as a visual display color frame of image data where each pixel position of frame 5206 is represented by a combination of red, green and blue values. In processing the Cy-Mg visual display color frame 5206 into a frame of image data including red, green, and blue values for each pixel position, optical reader 100 may first calculate white, cyan and magenta values for each pixel position of frame 5206. Where an original pixel position such as pixel position P₅₃(FIG. 16 c) is a cyan pixel, the cyan value is determined by directly reading the pixel value of the cyan pixel. A magenta value for cyan pixel at position P₅₃is calculated by interpolation utilizing the magenta values of surrounding pixel positions of magenta pixels such as positions P₅₂, P₄₃, P₆₃, P₅₄(FIG. 16 c). A white value for cyan pixel at position P₃₅is calculated by interpolation using pixel values from monochrome pixel positions that surround cyan pixel P₅₃. Referring to FIG. 5 b, a supplemental frame including monochrome pixel values may be captured, e.g., successively before or after frame 5206 is captured for purposes of interpolating a white value for each color pixel of the color filter array windowed frame 5206. Alternatively, the color filter array frame 5206 captured at step 1405 may include monochrome pixel image data for purposes of interpolating a white value for each color pixel value. When white, cyan and magenta values are calculated for each pixel of frame 5206, the white, cyan, and magenta values are readily converted into red, green, and blue values. Alternatively, display 504 can be configured to be responsive to white, cyan and magenta signals for each pixel of display 504. A set of transform equations for transforming a set of white, cyan and magenta values for a given pixel of a frame into a set of red, green and blue values for that pixel is given as follows.
R=W−Cy (Eq. 1)
G=Mg+Cy−W (Eq. 2)
B=W−Mg (Eq. 3)
In the process described relative to the flow diagram of FIG. 14 g, an original color filter array frame is processed into a visual display color frame of image data of reduced spatial resolution (a reduced spatial resolution 320×256 visual display color frame of image data may be produced using a hybrid monochrome and color image sensor array having a 1280×1024 pixel resolution). With reference to FIG. 14 h, a process for producing a high spatial resolution visual display color image is described. In the process described relative to the flow diagram of FIG. 14 h, optical reader 100 utilizes image data from both monochrome pixels 250M and color pixels 250C from a hybrid monochrome and color image sensor array such as image sensor array 182A or image sensor array 182B in the generation of a visual display color image having spatial resolution equal to or on the order of the overall pixel resolution of the image sensor array.
At step 1408 control circuit 552 captures a color filter array image data frame by selectively addressing color pixels 250C of an image sensor array and selectively reading out image data from color sensitive pixels 250M. The frame of image data captured at step 1408 is a windowed frame of image data. For reduction of cross talk resulting from light entering monochrome pixels 250M, the monochrome pixels of image sensor array 182A, 182B may be reset using reset control timing pulse 370, 370′, 370″, 370″′ at the time that exposure control timing pulse 354, 354′, 354″, 354″′ is applied to expose color pixels for capture of a color filter pattern image frame at step 1408.
At step 1409 control circuit 552 captures a monochrome frame of image data by selectively addressing monochrome pixels 250M of array 182A, 182B and selectively reading out image data from monochrome 280M pixels. The frame of image data captured at step 1409 is a windowed frame of image data. For reduction of cross-talk resulting from light entering color pixels 250C the color pixels of image sensor array 182 may be reset using reset control timing pulse 370, 370′, 370″, 370″′ at the time that exposure control timing pulse 354, 354′, 354″, 354″′ is applied to expose monochrome pixels for capture of a monochrome, typically gray scale or binarized image frame at step 1409.
At step 1410 control circuit 552 transfers both the color filter array frame captured at step 1408 and the monochrome image frame captured at step 1409 to fusion circuit 1708. Fusion circuit 1708 takes as inputs the color filter array image data frame and the monochrome image data frame and processes them into a high resolution visual display color frame of image data.
Referring to FIG. 14 i, an example of the process 1440 which may be executed by fusion circuit 1708 (FIG. 1 e) to process a combination of monochrome image data and color image data into a visual display color frame of image data is described. As explained with reference to FIG. 1 e, fusion circuit 1708 may be physically embodied by the combination of a control circuit provided by a CPU 552 operating in combination with memory 566 that stores an executable program. The specific process described with reference to FIG. 14 i is executed utilizing an optical reader 100 including substantially uniform dimensional pixel image sensor array 182B. At step 1442 of process 1440 control circuit 552 generates color filter array image data and monochrome gray scale image data. Where optical reader 100 includes image sensor array 182B, control circuit 552 may execute step 1442 by reading out from image sensor array 182B a single frame of image data comprising both monochrome image data and color image data. Control circuit 552 may also execute step 1442 by successively capturing a first monochrome frame comprising monochrome image data and then a second color frame comprising color image data. Control circuit 552 at step 1442 may drive monochrome pixels 250M into reset during an exposure period for read out of color image data from color sensitive pixels 250C. When generating a frame of monochrome image data at step 1442, control circuit may interpolate monochrome pixel values for “missing pixel” positions occupied by color sensitive pixels 250C.
At step 1446 control circuit 552 generates an RGB image having resolution equal to the color sensitive subset of pixels of image sensor array 182B. In an RGB image, each pixel of the image is represented by a red color value, a green color value and a blue color value. The RGB image generated at step 1446 may have the same characteristics as the visual display image received by optical reader 100 at step 1407 of the alternative process described in connection with FIG. 14 g. Where a color filter array image captured at step 1442 is a Bayer pattern image, the RGB image generated at step 1446 is derived by executing a demosaicing routine as described herein. Where the color filter array image captured at step 1442 is a CMY image or a CM image (cyan and magenta only) image as described in connection with FIGS. 2 b and 2 d, the RGB image generated at step 1446 is derived by way of a transformation process as described herein in connection with equations 1, 2 and 3. With further reference to process 1440 which may be executed by fusion circuit 1708 control circuit 552 at step 1450 expands the pixel count of the RGB image generated at step 1446 so that the pixel count of the color image is equal to the pixel count of the monochrome image captured at step 1442 (at step 1442 monochrome pixels from the captured monochrome image may be interpolated as described with FIG. 16 a). When control circuit 552 executes step 1450, the monochrome gray scale image generated at step 1442 and the color image at that stage of the processing have equal numbers of pixels such that each pixel position e.g., pixel of the monochrome image has a corresponding pixel position in the color image. With reference to image sensor array 182B having a period of P=2, there are four times as many monochrome pixels as there are color sensitive pixels. Accordingly, with image sensor array 182B having a period of P=2, control circuit 552 at step 1450 expands each pixel into a 2×2 pixel block. Where image sensor array 182B has a period P=3, control circuit 552 at step 1450 expands each pixel into a 3×3 pixel block. Where image sensor array 182B includes the period of P=4, control circuit 552 at step 1450 expands each pixel into a 4×4 pixel pixel block. At step 1454 control circuit 552 calculates an intensity value I_cfor each pixel position of the expanded color image. Control circuit 552 at step 1454 calculates an intensity value for each pixel position of the expanded color image according to the formula.
I _c=0.299R+0.587G+0.144B (Eq. 4)
Control circuit 552 at step 1460 then calculates an intensity value delta, D, for each pixel position, (Px, Py) utilizing a monochrome image intensity value I_mand an expanded image color intensity value, I_c, at each pixel position. Control circuit 552 at step 1460 may calculate an intensity value delta for each pixel position of the monochrome and expanded color image according to the formula
D(P _x ,P _y)=I _m(P _x ,P _y)−I _c(P _x ,P _y) (Eq. 5)
At step 1464, control circuit 552 updates the RGB data set color scale values of the expanded RGB color image using the set of formulas
R′(P _x ,P _y)=R(P _x ,P _y)+D(P _x ,P _y) (Eq. 6)
G′(P _x ,P _y)=G(P _x ,P _y)+D(P _x ,P _y) (Eq. 7)
B′(P _x ,P _y)=B(P _x ,P _y)+D(P _x ,P _y) (Eq. 8)
At step 1468 control circuit 552 truncates RGB data set color scale values that are greater than 255 (where an 8 bit gray scale is used). After control circuit 552 truncates RGB values greater than 255, control circuit 552 at step 1770 outputs a visual display color frame of image data having a spatial resolution equal to or approximately equal to the overall pixel resolution of image sensor array 182B. The visual display color frame of image data output at step 1770 may have a number of RGB data sets equal to the overall pixel count (e.g., monochrome pixels plus color sensitive pixels) of image sensor array 182B.
At step 1411 optical reader 100 receives from fusion circuit 1708 a high resolution visual display color frame of image data. The visual display color frame of image data received at step 1411 may include a pixel resolution equal to or on the order of the pixel resolution of image sensor array 182B. Optical reader 100 may be regarded as having received a visual display color frame of image data when fusion circuit 1708 outputs a visual display color frame of image data at step 1470.
When executing process 1440, control circuit 552 fuses monochrome and color image data to produce a high resolution visual display color frame of image data. When executing the alternative process described with reference to the flow diagram of FIG. 14 j, control circuit 552 fuses monochrome and color image data in such a manner that color reproduction is optimized.
In general, increasing the percentage of monochrome pixels 250M in image sensor array 182A, 182B increases indicia decoding accuracy, while increasing the percentage distribution of color sensitive pixels 250C in image sensor array increases color reproduction accuracy. Because of the light transmissivity of monochrome pixels, an image obtained utilizing an image sensor array having a higher percentage of monochrome pixels 250M has a higher signal to noise ratio than an image obtained utilizing an image sensor array having a smaller percentage of monochrome pixels 250M. Accordingly, an image obtained utilizing an image sensor array having a higher percentage of monochrome pixels often produces an image with greater detail and improved overall visual quality.
Optical reader 100 in another aspect may incorporate the structure shown in FIG. 21. In FIG. 21, center pixels 2072 of reader image sensor array 182B have a higher percentage of monochrome pixels 250M, i.e., a period of P=4, as shown in FIG. 5 e, while outer pixels 2074 have a lower percentage of monochrome pixels 250M, i.e., a period of P=2, as shown and described in FIG. 5 c. The image sensor array 182B is constructed such that center pixels 2072 are optimized for providing image data yielding increased decoding accuracy while outer pixels 2074 are optimized for providing image data yielding increased color reproduction accuracy.
Referring to further steps of process 1400, control circuit 552 at step 1412 outputs the visual display color frame of image data obtained at step 1404. At step 1412 control circuit 552 may output a visual display color frame of image data to display 504 for visual observation by an operator or to a designated color frame storage memory location of reader 100 such as a designated frame memory storage location of Flash memory 564 or to another frame memory location of system 145. Where control circuit 552 is incorporated in hand held housing 101, control circuit 552 at step 1410 may also send a visual display color frame of image data to spaced apart device 150, as shown in FIG. 10. For sending a frame of image data to a spaced apart device 150, optical reader 100, the spaced apart device 150, and a communication link there between may be configured to transmit data packets in accordance with a protocol of the TCP/IP suite of protocols. Further, optical reader 100 may format the visual display color frame of image data obtained at step 1412 in a suitable image file format (e.g., .BMP, .TIFF, .PDF, .JPG, .GIF) and optical reader 100 may automatically send the visual display color frame of image data at step 1412 utilizing the file transfer protocol (FTP). Optical reader 100 at output step 1212 may format the visual display color frame of image data in a suitable image file format (e.g., .BMP, .TIFF, .PDF, .JPG, .GIF) when storing the visual display color frame of image data in memory 566 (which can be incorporated in hand held housing 101) or when sending the visual display color frame of image data to a spaced apart device 150 for storage. Optical reader 100 may also transmit a visual display color frame of image data utilizing a suitable markup language such as .XML. Referring to FIG. 10, system 145 may be configured so that when a display equipped spaced apart device 150 receives a visual display color frame of image data from optical reader 100, the spaced apart device 150 automatically displays that received visual display color frame of image data on a display 1504 associated with that device.
Optical reader 100 can be configured so that all the steps of process 1400 are carried out automatically in response to receipt of a trigger signal until a stop condition is satisfied. A stop condition may be the receipt of a trigger stop signal such as may be generated by the release of trigger 216.
In the embodiments of FIGS. 14 a-14 c, two actuations of a reader control button are made to carry out an indicia decode process and two actuations of a reader control button are made to carry out a picture taking process (one actuation of button 3162 or button 3164 to configure the reader 100 and then another actuation of trigger 216 to capture an image). It will be understood that optical reader 100 can be configured to carry out indicia decoding or picture taking with a single actuation of a reader control button. For example, optical reader 100 can be configured so that actuation of virtual button 3162 both configures reader 100 to decode and simultaneously generates a trigger signal to immediately commence image capture and decoding. Optical reader 100 can also be configured so that actuation of virtual icon button 3164 both configures a reader 100 for picture taking and simultaneously generates a trigger signal to immediately commence image capture.
While process 1200 and process 1400 may be carried out in the alternative, process 1200 and process 1400 may also be executed contemporaneously. For example, while control circuit 552 obtains a decode frame at step 1204, control circuit 552 may obtain a visual display color frame of image data at step 1404. Control circuit 552 may obtain a color frame of image data as a decode frame at step 1204 and then outputs that frame at step 1212 as visual display color frame of image data. Control circuit 552 at step 1412 may output a visual display color frame of image data and contemporaneously transfer that frame of image data to decode circuit 1702. In general, reader 100 may be configured so that whenever control circuit 552 obtains a decode frame at step 1204, control circuit 552 may store that frame for later processing, which processing may include processing for generating a visual display color frame of image data and which processing may be responsive to an operator input command to perform such processing. Optical reader 100 may also be configured so that when control circuit 552 obtains a visual display color frame of image data at step 1404, control circuit may store that frame for further processing, which processing may include transferring that frame to decode circuit 1702 or autodiscrimination circuit 1704, and which processing may be responsive to an operator input command to perform such processing.
Another embodiment of the invention is described with reference to FIGS. 17 a-17 g. In the embodiment of FIGS. 17 a-17 g optical reader 100 includes a pair of imaging modules 1802D and 1802E. Imaging module 1802D is a color imaging module having color image sensor array 182D. Color image sensor array 182D includes a Bayer pattern color filter with one of red, green or blue wavelength selective filter disposed on each pixel. Imaging module 1802E as shown in FIG. 17 e is a monochrome imaging module having a one-dimensional solid state image sensor array 182E. One-dimensional monochrome image sensor array 182E in the embodiment of FIGS. 17 a, 17 e, 17 f, and 17 g includes an M×1 (one row) array of monochrome (without color filter) pixels. One-dimensional image sensor array 182E may also include and M×N array of pixels, where M>>N, e.g., an M×2 (2 rows) of pixels.
The reader 100 shown in the electrical block diagram of FIG. 17 a has many of the same components as shown in optical reader 100 of FIG. 1 a. Namely, optical reader 100 of FIG. 17 a includes a control circuit 552 provided in the example by a CPU, which operates under the control of program data stored in EPROM 562. Control circuit 552 is in communication with a memory unit 566 that includes in addition to EPROM 562, RAM 560, and Flash memory 564. Control circuit 552 further receives input control data from various user input devices such as manual trigger 216, pointer controller 512, keyboard 508 and touch screen 504T. Control circuit 552 may also output data such as decoded output data and visual display image data to color display 504. For capturing image data, control circuit 552 may control either image sensor array 182E or image sensor array 182D. For capturing one-dimensional image data corresponding to a one-dimensional slice image of a target, control circuit 552 sends various image capture initiating control signals to one-dimensional image sensor array 182E. In response to the image capture initiation control signals, image sensor array 182E sends analog image signals to signal processing circuit 591 which among various processing functions amplifies the signals and feeds the signals to analog-to-digital converter 592. Analog-to-digital converter 592 converts the signals into digital form and routes the digital image data to FPGA 593 which under the control of control circuit 552, manages the transfer of the digital information into RAM 560, where the monochrome image data can be accessed for decoding processing by control circuit 552. For capturing two-dimensional frames of color image data, control circuit 552 sends appropriate image capture initiation control signals (e.g., exposure, read out) to image sensor chip 1082. FPGA 580 receives digital image data from image sensor IC chip 1082, 1082D and under the control of control circuit 552 manages the transfer of color image data into RAM 560. Illumination assembly 104 for each module 1802D, 1802E may be controlled during image acquisition as explained with reference to the timing diagrams of FIGS. 15 a-15 e.
Optical reader 100 as shown in FIGS. 17 a-17 g may be operated in accordance with the flow diagram of FIGS. 17 a-17 g. Namely, by a suitable selection method such as by depressing icon 3162 or icon 3164 (FIG. 9 b) one of a decode mode of operation and a color image capture mode of operation can be selected. However, in the dual imaging module embodiment of FIGS. 17 a-17 g, the imaging module which is utilized for capturing image data depends on which mode (indicia decoding, or picture taking) is selected. If the indicia decode mode is selected at step 1100 (FIG. 14 a) and a trigger signal is received, optical reader 100 proceeds to step 1102 to execute indicia decode process 1200 (FIG. 14 a). At step 1204 of indicia decode process 1200, control circuit 552 obtains a decode frame of image data. If the picture taking mode of operation is selected at step 1100 (FIG. 14 a) and a trigger signal is received, control circuit 552 proceeds to step 1404 (FIG. 14 c) to obtain a visual display color frame of image data. Where reader 100 includes two imaging modules, one color such as module 1802, 1802D having color image sensor array 182, 182D and one monochrome such as module 1802, 1802E having monochrome image sensor 182, 182E, the particular image sensor array 182 to which control circuit 552 sends control signals for initiating image capture depends on whether optical reader 100 is operating in a decode mode of operation or a picture taking mode of operation. With reference to the reader 100 of FIGS. 17 a-17 g, and the flow diagrams of FIGS. 14 a, 14 b and 14 c, reader 100 at step 1204 sends image capture initiation control signals to monochrome one-dimensional image sensor array 182, 182E to initiate image capture without sending any image capture initiation control signals to color image sensor array 182, 182D if the reader 100 is operating in a decode mode operation. Reader 100 at step 1404 sends image capture initiation control signals to color image sensor array 182, 182D without sending any image capture initiation control signals to monochrome image sensor array 182, 182E if reader 100 is operating in a picture taking mode operation. Accordingly, where optical reader 100 is in an indicia decode mode and receives a trigger signal, a monochrome frame of image data is sent to RAM 560 for further processing by decode circuit 1702 (FIG. 10). Where optical reader 100 is in a picture taking mode and receives a control signal, a color image is sent to RAM 560. The color image if a Bayer pattern image is subject to a demosaicing process as described herein for generating a visual display color frame of image data, which visual display color frame of image data may be output by control circuit 552 e.g., to display 504 and/or a designated memory address of system 145 (e.g., memory 566 or another memory such as a memory of a spaced apart device 150), and/or to a display 1504 of a spaced apart device 150 of system 145 (FIG. 5).
When an image is captured by the two imaging module readers of FIGS. 17 a-17 g, the type of image capture (monochrome or color) depends on a selected operating mode. When an indicia decode mode is selected, a monochrome gray scale image well suited for decode processing is captured. When a picture taking mode is selected, a color image is captured which is well suited for visual display.
Further aspects of a dual imaging module reader are described with reference to FIGS. 17 b-17 g. FIGS. 17 b and 17 c illustrate that the hardware block 598 of reader 100 shown in FIGS. 17 a, 17 f, and 17 g may be replaced with alternative hardware blocks. As indicated by FIG. 17 b, hardware block 398 which in FIG. 17 a includes a CCD one-dimensional solid state image sensor array 182E and off-board signal processing circuit 591, analog-to-digital converter 592 and FPGA 593 may be replaced by a hardware block including an CMOS image sensor IC chip 1082F including a monochrome image sensor array 182F. Image sensor IC chip 1082, 1082F is of construction similar to image sensor IC chip 1082, 1082A and IC chip 1082, 1082D except that image sensor array 182F of chip 1082F includes monochrome pixels 250, 250M only and is devoid of color sensitive pixels 250, 250C. FIG. 17 c illustrates that imaging assembly hardware block 598 can be replaced with a laser scanning bar code engine 594 and an associated decode circuit 595. Laser scanning bar code engine 594 and associated decode circuit 595 may be available in a package known as an SE 923 decoded out scan engine available from Symbol Technologies. In the embodiment of FIG. 17 c, steps 1210, 1212, 1214 of decode process 1200 are carried out by decode circuit 595.
Exemplary imaging modules supporting various types of image sensor IC chips are shown in FIGS. 17 d and 17 e. FIG. 17 d shows an exemplary imaging module for supporting image sensor IC chip 182D. Imaging module 1082D includes the elements shown and described with reference to FIGS. 8 a-8 d except that imaging module 1082D includes image sensor IC chip 182D and further except that certain light sources are optionally deleted. Imaging module 1082E includes the elements shown and described with reference to FIGS. 8 a-8 e except that imaging module 1082E includes one-dimensional monochrome image sensor chip 182E and further except that certain light sources of illumination block 104 are optionally deleted. With module 1802E, aiming pattern 1838 (FIG. 8 d) may serve as an aiming and illumination pattern. Further, it will be noted that illumination assembly 104 of an imaging module herein may include a flash illumination light source, 160, 160X (FIG. 9 a). It may be particularly useful to incorporate a flash illumination into illumination assembly 104, where an imaging module 1082 is used primarily for capture of visual display color image.
Referring to FIGS. 17 f and 17 g construction views of dual imaging module readers incorporated in various optical reader housings are shown and described. In FIG. 17 f a gun style optical reader 100 is shown having color two-dimensional imaging module 1802D and one-dimensional monochrome imaging module 1082E supported therein. In FIG. 17 g a portable data terminal (PDT) optical reader 100 is shown having color two-dimensional imaging module 1802D and one-dimensional monochrome imaging module 1802E supported therein. The dual modules can also be installed in other types of housings such as cell phone housings (FIG. 9 c) and personal data assistant housings (PDAs). In the examples of FIGS. 17 f and 17 g, imaging modules 1802 are supported by struts 597 formed on an interior wall 1802 of housing 101. Via ribbon connectors 598, the modules 1802 in each example are in communication with a main printed circuit board 599 which includes various electrical components including processor IC chip 548.
In one application, the optical reader 100 of FIGS. 17 a-17 g is operated in the following manner. An operator actuates color image sensor array 182D to take a color picture of parcel 1260 (FIGS. 11 and 12) carrying a bar code symbol 1266, 1270. Such actuation may be carried out, e.g., by depressing decode button 3164 and then trigger 216 or button 3164 only. An operator then actuates monochrome image sensor array 182E (or alternatively image sensor array 182F, or laser scan engine 594) to decode bar code symbol 1266, 1270. Such actuation may be carried out e.g., by depressing button 3162 and then trigger 216 or by depressing button 3162 only. Further, control circuit 552, which may be incorporated in hand held housing 101, may transmit a visual display color frame of image data representing parcel 1260 and decoded out messages corresponding to one or more of symbols 1266, 1270 to remote server 184 (FIG. 10). System 145 can be configured so that such transmission is automatic in response to trigger signals being received, or optical reader 100 can be configured so that associated color picture data and decoded out bar code message data are transmitted in response to receipt of a user-initiated command input into a user-interface of optical reader 100 to transmit associated picture and decoded bar code message data.
With further reference to the reader electrical block diagram shown in FIG. 1 a, various useful optical reader embodiments may be yielded by reconfiguration of hardware block 208 including an image sensor array. With reference to FIG. 18 a, an optical reader 100 having the hardware components shown in FIG. 1 a may be modified to include an image sensor array 182C as shown and described in connection with FIG. 18 a. In the embodiment of FIG. 18 a, optical reader 100 includes cyan-magenta-yellow (CMY) color filter array 182C. Each pixel 250 of image sensor array 182C includes a color filter element; namely one of a cyan color filter element, a magenta color filter element or a yellow color filter element. Yellow color filter elements have excellent light transmittance (approaching the transmittance of a monochrome pixel). Further, it is seen that in accordance with the CMY color filter pattern shown in FIG. 18 a that approximately 50% of all pixels of image sensor array 182C are yellow pixels (pixels having a yellow light wavelength sensitive filter element). In the specific example of FIG. 18 a, image sensor array 182C having cyan, magenta and yellow pixels is devoid of green pixels. However, image sensor arrays are available which have green pixels in addition to cyan, magenta and yellow pixels. Image sensor array 182C may be incorporated into an optical reader 100 that operates in accordance with the picture taking mode/indicia decode mode flow diagram described in connection with FIG. 14 a. That is, when driven into a indicia decode mode of operation as described in connection with FIG. 14 b, optical reader 100 including CMY color image sensor array 182C obtains a decode frame of image data whereas when optical reader 100 including image sensor array 182C is driven into a picture taking mode of operation, optical reader 100 obtains a visual display color image frame of image data as described in connection with FIG. 14 c herein.
According to the invention, an optical reader including a CMY image sensor array 182C as shown in FIG. 18 a may obtain image data in a manner that depends on which operational mode (indicia code or picture taking) is selected. Where optical reader 100 including CMY image sensor array 182C obtains a decode frame of image data at step 1204, control circuit 552 of optical reader 100 can selectively address yellow color pixels of CMY image sensor array 182C and selectively read out image data only from yellow colored pixels of image sensor array 182C. With further reference to a reader including image sensor array 182C, control circuit 552 at step 1204 may interpolate missing pixel values corresponding to the pixel positions of magenta and cyan pixels of image sensor array 182C. After interpolating the missing pixel positions, control circuit 552 at step 1210 may transfer the interpolated decode frame to one of indicia decode circuit 1702 or autodiscrimination circuit 1704.
In a further aspect of the optical reader described in connection with FIG. 18 a including a CMY color image sensor array 182C, image sensor array 182C may include separate and independent reset control lines for facilitating the reset of magenta (labeled “Mg”) and cyan (labeled “Cy”) pixels independent from the resetting of yellow pixels (labeled “Y”). Accordingly, when image data at step 1204 is read out selectively from yellow pixels, the magenta and cyan pixels of image sensor array 182C may be driven into reset to eliminate electron diffusion cross talk and to reduce cross talk attributable to photons entering image sensor array 182C through magenta and cyan color pixels 250C.
When obtaining a visual display color frame of image data as described at step 1404 of the flow diagram FIG. 14 c an optical reader including image sensor array 182C may simply read out image data from all of the pixels of the array 182C and execute a simple demosaicing algorithm to convert a single color value for each pixel of image sensor array 182C into a visual display color image wherein each pixel of image sensor array 182C is represented by a data set including three color scale values, e.g., a cyan color scale value, a magenta color scale value and a yellow color scale value.
Control circuit 552 at step 1404 where the reader includes a CMY image sensor array 182C may transform the CMY visual display image into an RGB visual display image utilizing a CMY to RGB transformation process as described herein.
The performance of optical reader 100 may be hindered where optical reader 100 is operated to read bar code symbols or other indicia disposed on a substrate having a shiny surface (e.g., metal, glass, laminated, plastic, etc.). Light rays emanating from light sources 160 of reader 100 that are projected on a highly reflective shiny surface of a substrate, s, may be substantially entirely reflected directly on to image sensor array 182. “Specular” reflection is said to occur where a substantial percentage of light rays are reflected and directed onto image sensor array 182. Light rays are said to be reflected at a “specular angle” when light rays are reflected from a surface at about the angle of incidence. Specular reflection tends to saturate image sensor array 182 to cause decoding failures. The optical reader 100 described in connection with FIGS. 19 a-c is configured so that read errors resulting from specular reflection are reduced. As shown and described in connection with FIG. 19 a, hardware block 208 shown in FIG. 1 a as including a hybrid monochrome in color image sensor array 182A can be replaced with hardware block 208 as shown in FIG. 19 a including a hybrid monochrome and polarizer filter image sensor array 182G.
Image sensor array 182G includes a first subset of monochrome pixels 250M and a second subset of light polarizing pixels 250P. Light polarizing pixels 250P of image sensor array 182G include light polarizing filter elements 261 (alternatively termed “light polarizing filters,” or simply “light polarizers”) typically formed at each polarizing pixel 250P in the position of filter 260 as shown in the color pixel views of FIGS. 3 c and 6 c. Light polarizing filter elements 261 of image sensor array 182G, 182H can be deposited onto the major body of light polarizing pixels 250P by way of a depositing process. Light polarizing filter elements 261 of image sensor array 182G can be constructed to attenuate polarized light rays generated from an appropriately polarized light source and reflected at a specular angle. Accordingly, polarized light rays incident on the image sensor array on the polarizing pixels 250P are attenuated significantly; thus, reducing the contribution of specularly reflected light rays to generated image signals from the polarizing pixels 250P.
According to the invention, optical reader 100 including image sensor array 182G may be configured to selectively address light polarizing pixels 250P and selectively read out image data from light polarizing pixels 250P to generate image data for subjecting to decoding which is likely to result in successful reading of bar codes or other indicia notwithstanding the image data being obtained during specular reflections read conditions.
Referring to FIG. 19 b, a perspective view of light polarizing image sensor array 182G is shown with an exploded view showing a pattern which may be repeated throughout the array. In the version of FIG. 19 b, light polarizing pixels 250P having light polarizing light filter elements 261 are uniformly distributed throughout image sensor array 182G with a period of P=2. It will be understood that light polarizing pixels 250P may also be distributed throughout image sensor array 182G in a uniform or substantially uniform distribution pattern other than the pattern shown in FIG. 19 b. For example, light polarizing pixels 250P may be distributed throughout image sensor array 182G with a distribution pattern of P=3, (as described in connection with FIG. 5 d showing a hybrid monochrome and color image sensor array) or a distribution pattern having the period of P=4, as illustrated with reference to hybrid monochrome and color image sensor array as shown in FIG. 5 e.
Referring to the view of FIG. 9 b, optical reader 100 may be operated in a mode in which optical reader 100 captures image data by selectively addressing polarizing pixels 250P and selectively reading out image data from light polarizing pixels 250P only. Optical reader 100 may be configured to have a reduced specular reflection read error decode mode. Optical reader 100 can be configured so that when button 3156 is actuated, optical reader 100 receives a trigger signal to obtain image data that is likely to result in successful reading notwithstanding specular reflection reading conditions.
Referring to the flow diagram of FIG. 19 c, optical reader 100 at step 1902 may receive a trigger signal to commence operation in a reduced specular reflection read error decode mode. The trigger signal may be received pursuant to a manual control by an operator such as an actuation of control button 3156. Control circuit 552 may also be configured to receive the trigger signal at step 1902 when control circuit 552 automatically senses a predetermined condition such as a saturation condition. Control circuit 552 at step 1902 may determine that a saturation condition is present by analysis of image data at step 1204 (FIG. 14 b) during normal decoding operations so that when a saturation condition is detected, optical reader 100 automatically commences operation in a reduced specular reflection read error decode mode. In a specific embodiment of the invention, control circuit 552 may determine that a saturation condition is present when an average white value of monochrome image data is below a predetermined level.
At step 1904 optical reader 100 obtains a specular reflection read condition decode frame of image data. Control circuit 552 obtains a specular reflection condition decode frame of image data at step 1902 by selectively addressing light polarizing pixels 250P of image sensor array 182G and selectively reading out image data from light polarizing pixels 250P only. In another aspect of image sensor array 182G that may be incorporated in optical reader 100, image sensor array 182G may include separate reset control lines for resetting monochrome pixels 250M separately and independently of light polarizing pixels 250P. Image sensor array 182G may have separate sets of reset control lines as described in connection with image sensor array 182G, particularly in connection with FIG. 7 a.
Accordingly, when control circuit 552 selectively addresses light polarizing pixels 250P for read out of image data from light polarizing pixels 250P, control circuit 552 drives monochrome pixels 250M into reset. Resetting of monochrome pixels 250M is synchronized with the exposure period for exposing light polarizing pixels 250P as described herein. Driving monochrome pixels 250M into reset while light polarizing pixels 250P are exposed eliminates electron diffusion cross talk and reduces cross talk resulting from photon penetration to image sensor array 182G.
At step 1904, control circuit 552 may interpolate pixel values at pixel positions corresponding to missing pixel positions. At step 1906 control circuit 552 transfers the specular reflection condition decode frame of image data obtained at step 1904 to indicia decode circuits 1702 or autodiscrimination circuit 1704 as are described in connection with FIG. 1 e.
At step 1908 control circuit 552 receives decoded output data output by decode circuit 1702 or signature autodiscrimination circuit 1704. At step 1910 control circuit 552 outputs decoded out data, e.g., by transferring decoded out data to an on reader display 504 or to a spaced apart display 1504 or else stores decoded data in appropriate memory address location of system 145 (FIG. 10).
A process has been described with reference to the flow diagram of FIG. 19 c wherein control circuit 552 selectively reads out monochrome pixel image data from monochrome pixels 250M and selectively reads out image data from light polarizing pixels 250P. An optical reader including hybrid monochrome and light polarizing image sensor array 182G may also be operated without selectively reading out image data from image sensor array 182G. An optical reader incorporating hybrid monochrome and light polarizing image sensor array 182G can be operated to decode decodable indicia and to take pictures in accordance with the process described with reference to the flow diagrams of FIGS. 14 a, 14 b, and 14 c. In obtaining a decode frame of image data (step 1204, FIG. 14 b), control circuit 552 may read out image data from all pixels of hybrid monochrome and light polarizing image sensor array 182G including image data from all monochrome pixels 250M and all light polarizing pixels 250P in a single frame capture step. The full frame monochrome and light polarizer pixel image data can also be captured with two frame capture steps. At step 1210, control circuit 552 may transfer to decode circuit 1702 or autodiscrimination circuit 1704 the full frame of monochrome and polarized pixel image data obtained at step 1204. If decode circuit 1702 or autodiscrimination circuit 1704 fails to decode or fails to detect the presence of handwritten characters, control circuit 552 may, after step 1210, transfer a subset of full frame of image data originally transferred at step 1210. Namely, after step 1210, if decoding or autodiscrimination fails, control circuit 552 may transfer to decode circuit 1702, or autodiscrimination circuit 1704 a reduced resolution image extracted from a full frame image by selectively extracting monochrome image data from the full frame of image data. The reduced resolution frame of image data includes only image data corresponding to light polarizing pixels 250P of image sensor array 182G. The failure of decode circuit 1702 to decode or autodiscrimination circuit to recognize may be regarded as a determination by control circuit 552 that a saturation condition is present.
The elements of a hybrid monochrome and color image sensor array (such as image sensor array 182A or 182B) as described herein can be combined with the elements of a hybrid monochrome and light polarizing image sensor array 182G into a single image sensor array. FIGS. 20 a and 20 b show an image sensor array 182H including a first subset of monochrome pixels 250M, a second subset of color sensitive pixels 250C and a third subset of light polarizing pixels 250P. Image sensor array 182H may include three separate sets of reset control lines to enable separate and independent of resetting of monochrome pixels 250M, of color sensitive pixels 250C and of light polarizing pixels 250P. Image sensor array 182H may be incorporated in hand held optical reader 100 and may be substituted for hardware block 208 as shown in FIG. 1 a. Optical reader 100 incorporating image sensor array 182H may have operating modes in which optical reader separately addresses monochrome pixels 250M for read out of image data from monochrome pixels 250M only. Optical reader 100 including image sensor array 182H may also have an operating mode in which optical reader 100 selectively addresses color sensitive pixels 250C and selectively reads out image data from color sensitive 250C. Optical reader 100 may also have an operating mode in which optical reader 100 selectively addresses light polarizing pixels 250P and selectively reads out image data from light polarizing pixels 250P. Optical reader 100 may obtain a full frame of image data including monochrome, color and light polarizing pixels image data (obtained with one, two, or three frame capture steps) and then utilize the image data on an as needed basis. For example, if a decode attempt utilizing the full frame image data fails, optical reader 100 may selectively extract light polarizing pixel image data from the full frame image data and transfer the extracted image data to decode circuit 1702.
In general, optical reader 100 including image sensor array 182H selectively reads out image data from monochrome pixels 250M in obtaining a decode frame of image data for transferring to a decode circuit 1702 under normal read conditions. Optical reader 100 selectively reads out image data from color sensitive pixels 250C when obtaining image data for use when obtaining a visual display color frame of image data. Optical reader 100 selectively reads out image data from light polarizing pixels 250P, or selectively extracts image data corresponding to pixels 250P from a frame of image data when optical reader 100 senses that a specular reflection is present or when an operator pursuant to operator control drives optical reader 100 into a reduced specular reflection read error decode mode of operation. An optical reader 100 including image sensor array 182H may operate in accordance with the picture taking and decode mode flow diagram as described in connection with FIG. 14 a and may execute the reduced specular reflection read error decode mode decoding process described in connection with FIG. 19 c.
For enhancing the performance of an optical reader according to the invention, having an image sensor array such as image sensor array 182G, 182H including light polarizing filters, optical reader 100 may incorporate emit optics light polarizers (which may alternatively be termed “light polarizing filter elements” or “light polarizing filters”). For example, a reader imaging module, e.g., module 1802A can include an optical plate 1962 as shown in FIG. 8 f which may be disposed forwardly of circuit board 1806 as shown in FIG. 8 a. Optical plate 1962 can incorporate light polarizers 1963 which polarize light from light sources 160S, 160T, that can be selectively energized when capturing images utilizing polarizing image sensor array 182G, 182H. Light polarizers 1963 can be cross-polarized relative to the polarizing filter elements 261 of image sensor array 182G, 182H. Optical plate 1962 can include other such elements as optical diffusers (not shown) for diffusing light rays emitted by light sources 160C-160T.
Further aspects of indicia decode circuit module 1702 and autodiscrimination circuit module 1704 are described with reference to FIGS. 22 a-22 i. Indicia decode circuit 1702 (which may be a bar code symbol dataform decode circuit) when receiving image data transferred by control circuit 552 may search the image data for markers, such as a quiet zone, indicative of the presence of a dataform, such as a one or two-dimensional bar code. If a potential decodable indicia (dataform) is located, the decode circuit 1702 applies one or more indicia decoding algorithms to the image data. If the decode attempt is successful, the optical reader outputs decoded dataform data. All of the circuits (modules) described with reference to FIG. 22 a can be incorporated in housing 101. Further, all of the circuits of FIG. 22 a can be embodied by the combination of control circuit 552 and memory 566.
Optical reader 100 may also include an autodiscriminating circuit 1704. Referring to FIG. 22 a, autodiscriminating circuit 1704 may incorporate a decode circuit 1702 and an image processing and analysis circuit 21208, that are in communication with one another.
As shown in this embodiment, the image processing and analysis circuit 21208 comprises a feature extraction circuit 21212, a generalized classifier circuit 21216, a signature data processing circuit 21218, an OCR decode circuit 21222, and a graphics analysis circuit 21224 that are in communication with each other. In addition, as shown in FIG. 22 a, the feature extraction circuit 21212 comprises a binarizer circuit 21226, a line thinning circuit 21228, and a convolution circuit 21230 that are in communication with each other.
FIG. 22 b shows a process 21300 for employing one embodiment of the invention utilizing the autodiscrimination circuit shown in FIG. 22 a. The process 21300 comprises an image reader recording an actuation event (step 21302), such as a receipt of a trigger signal, and in response at step 21304, collecting (obtaining) image data from a target with the optical reader 100. The collecting of image data step may be in accordance with step 1204 (FIG. 14 b). After collection, the image data is transferred (step 21308) to the decode circuit 1702. The dataform decode circuit searches (step 21310) the image data for markers, such as a quiet zone, indicative of the presence of a dataform, such as a one or two-dimensional bar code. If a potential dataform is located, the decode circuit 1702 applies (step 21314) one or more dataform decoding algorithms to the ensuing image data. If the decode attempt is successful, the optical reader 100 outputs (step 21318) decoded dataform data and signals (step 21322) a successful read with an alert, such as a beep tone.
In one embodiment if the decode attempt is not successful, the image data is transferred (step 21326) to the image processing and analysis circuit 21208. In another embodiment, the image data is processed in parallel with the attempt to decode the dataform data. In one such embodiment, the process that completes first (i.e., dataform decode attempt or the image processing) outputs its data (e.g., a decoded bar code or a captured signature) and the other parallel process is terminated. In a further embodiment, the image data is processed in response to the decoding of the dataform. In one such embodiment, a bar code encodes item information such as shipping label number and information indicating that a signature should be captured.
Within the image processing and analysis circuit 21208, the image data is processed by the feature extraction circuit 21212. In general, the feature extraction circuit generates numeric outputs that are indicative of the texture of the image data. As indicated above, the texture of the image data refers to the characteristics of the type of data contained in the image data. Common types of texture include one or two-dimensional bar code texture, signature texture, graphics texture, typed text texture, handwritten text texture, drawing or image texture, photograph texture, and the like. Within any category of texture, sub-categories of texture are sometimes capable of being identified.
As part of the processing of the image data by the feature extraction circuit 21212, the image data is processed (step 21328) by the binarizer circuit 21226. The binarizer circuit 21226 binarizes the grey level image into a binary image according to the local thresholding and target image size normalization. With the image data binarized, the image data is processed (step 21332) by the line thinning circuit 21228 to reduce multi-pixel thick line segments into single pixel thick lines. With binarized line thinned image data, the image data is processed (step 21336) by the convolution circuit 21230.
In general, the convolution circuit 21230 convolves the processed image data with one or more detector maps designed according to the invention to identify various textural features in the image data. In one embodiment, the convolution circuit 21230 generates a pair of numbers, the mean and variance (or standard deviation), for each convolved detector map. FIG. 22 c shows a set of 12 2×3 binary curvelet detector maps 21250 used to detect curved elements present in image data. As each of the curvelet detector maps 21250 is convolved with the image data, the mean value and the variance generated provide an indication of the presence or density of elements in the binarized line thinned image data having similar shapes to the curvelet detector maps 21250. As each pixel map generates a pair of numbers, the 12 curvelet detector maps 21250 generate a total of 24 numbers. According to one embodiment, these 24 numbers are representative of the curved or signature texture of the processed image data.
Further processing of the image data includes the outputs from the feature extraction circuit 21212 being fed (step 21340) into the generalized classified circuit 21216. The generalized classifier circuit 21216 uses the numbers generated by the feature extraction circuit as inputs to a neural network, a mean square error classifier or the like. These tools are used to classify the image data into general categories. In embodiments employing neural networks, different neural network configurations are contemplated in accordance with the invention to achieve different operational optimizations and characteristics. In one embodiment employing a neural network, the generalized classifier circuit 21212 includes a 24+12+6+1=43 nodes Feedforward, Back Propagation Multilayer neural network. The input layer has 24 nodes for the 12 pairs of mean and variance outputs generated by a convolution circuit 21230 employing the 12 curvelet detector maps 21250. In the neural network of this embodiment, there are two hidden layers of 12 nodes and 6 nodes respectively. There is also one output node to report the positive or negative existence of a signature.
In another embodiment employing a neural network, the 20 curvelet detector maps 21260 shown in FIG. 22 d are used by the convolution circuit 21230. As shown, the 20 curvelet detector maps 21260 include the original 12 curvelet detector maps 21250 of FIG. 22 c. The additional 8 pixel maps 21260 are used to provide orientation information regarding the signature. In one embodiment employing the 20 curvelet detector maps 21260, the generalized classifier circuit 21212 is a 40+40+20+9=109 nodes Feedforward, Back Propagation Multiplayer neural network. The input layer has 40 nodes for the 20 pairs of mean and variance outputs generated by a convolution circuit 21230 employing the 20 curvelet detector maps 21260. In the neural network of this embodiment, there are two hidden layers of 40 nodes and 20 nodes respectively, one output node to report the positive or negative existence of a signature, and 8 output nodes to report the degree of orientation of the signature. The eight output nodes provide 2⁸=256 possible orientation states. Therefore, the orientation angle is given in degrees between 0 and 360 in increments of 1.4 degrees.
In some embodiments, the generalized classifier circuit 21216 is capable of classifying data into an expanded collection of categories. For example, in some embodiments the generalized classifier circuit 21216 specifies whether the image data contains various data types such as a signature; a dataform; handwritten text; typed text; machine readable text; OCR data; graphics; pictures; images; forms such as shipping manifest, bill of lading, ID cards, and the like; fingerprints, biometrics such as fingerprints, facial images, retinal scans and the like, and/or other types of identifiers. In further additional embodiments, the generalized classifier circuit 21216 specifies whether the image data includes various combinations of these data types. In some embodiments, the general classifier circuit 21216 specifies whether the image data contains a specified type of data or not. In one such embodiment the image processing and analysis circuit 21208 is contained within an identification circuit that outputs an affirmative or negative response depending on the presence or absence of the specified data type, such as a signature or a biometric in the image data.
In one embodiment once the presence of a signature has been confirmed and its general orientation determined, image data is transferred (step 21344) to the signature data processing circuit 21218. In one embodiment, the signature data processing circuit 21218 is used to detect the boundaries of the signature in the image data. In one embodiment, the signature boundary is detected using a histogram analysis. As shown in FIG. 22 e, a histogram analysis consists of a series of one-dimensional slices along horizontal and vertical directions defined relative to the orientation of the signature. In one embodiment, the value for each one-dimensional slice corresponds to the number of black (i.e., zero valued) pixels along that pixel slice. In some embodiments if no bar codes have been decoded, then some specified region of the full frame of image data, such as a central region is captured for signature analysis. Once completed, the histogram analysis provides a two-dimensional plot of the density of data element pixels in the image data. The boundary of the signature is determined with respect to a minimum density that must be achieved for a certain number of sequential slices. In one embodiment, the histogram analysis searches inwardly along both horizontal and vertical directions until the pixel density rises above a predefined cutoff threshold. So that the signature data is not inadvertently cropped, it is common to use low cutoff threshold values.
In one embodiment, once the boundaries of the signature have been determined, the signature data processing circuit 21218 crops the image data and extracts the signature image data. In one such embodiment, the cropping is performed by an image modification circuit that generates modified image data in which a portion of the image data not including the signature has been deleted. In other embodiments, various compression techniques are employed to reduce the memory requirements for the signature image data. One such technique includes the encoding of the signature image data by run length encoding. According to this technique, the length of each run of similar binarized values (i.e., the length of each run of 1 or 0) for each scan line is recorded as a means of reconstructing a bit map. Another encoding technique treats the signature image data as a data structure where the elements of the data structure consist of vectors. According this encoding technique, the signature is broken down into a collection of vectors. The position of each vector in combination with the length and orientation of each vector is used to reconstruct the original signature. In one such embodiment, the encoding process generates a new vector whenever the curvature for a continuous pixel run exceeds a specified value. A further compression technique employs B-Spline curve fitting. This technique has the capacity to robustly accommodate curvature and scaling issues.
In various embodiments, the signature image data or a compressed or encoded version of the signature image data is stored locally on a dedicated memory device. In one such embodiment, the local memory device can be a detachable memory device such as a CompactFlash memory card or the like described in more detail below. In another embodiment, the signature image data is stored in a volatile or non-volatile portion of general purpose memory and downloaded at a future time. In a further embodiment, the signature image data can be transmitted via wired or wireless means either at the time of capture or at a later point, such as when a data collection session has been completed.
In another embodiment, the signature data processing circuit 21218 does not perform a histogram analysis but simply stores in memory the entire image or a compressed version once the presence of a signature has been determined. In a further embodiment to save processing time, the initial image analysis is performed on a lower resolution image. Once the presence of a signature is determined in this embodiment, a higher resolution image is taken. In one embodiment, a signature extraction histogram analysis is performed on this image. Next, the image is stored in memory in either compressed or original format. In some embodiments, the image data is combined with other data to form a record for a particular item such as a package or shipping envelope. As mentioned above, some of the additional data that can be collected by the optical reader 100 and stored with or separate from the signature data includes but is not limited to dataform data, handwritten text data, typed text data, graphics data, image or picture data, and the like.
As part of its operations, the image processing and analysis circuit 21208 can be designed to perform specialized tasks for different data types. For example, if the generalized classifier circuit 21216 determines that the image data contains typed or machine readable text, the image data can be collected, possibly histogram analyzed, and stored or alternatively, the image data can be transferred to the OCR decoding circuit 21222. Similarly, if the generalized classifier circuit 21216 determines that the image data includes a graphic element, the image data can be transferred to the graphics analysis circuit 21224 for processing. In one embodiment, the graphics analysis circuit 21224 is configured to recognize and decode predefined graphics. In one such embodiment, the graphics analysis can include determining which, if any, boxes have been selected in the billing and shipping instructions on a shipping label. In a further embodiment, the graphics analysis can include locating and decoding the typed or handwritten text contained in the zip code box on a shipping label. In an alternative embodiment, the optical reader 100 can be configured to automatically attempt decode operations in addition to the dataform decode, such as OCR decoding or graphics decoding, prior to the activation of the feature extraction circuit 21212.
In another embodiment, the image processing and analysis circuit 21208 segments the image data into regions and performs a feature extraction and general classification analysis on each region. In one embodiment as shown in FIG. 22 f, the standard rectangular image data window is divided into four equal sized sub-rectangles. In another embodiment shown in FIG. 22 g, the segmentation consists of overlapping regions so that the total area of the segmented regions is larger than that of the complete field of the image data. In FIG. 22 g there are seven shown overlapping regions where each identifying numeral is shown in the center of its region. In a further embodiment shown in FIGS. 22 h and 22 i, the segmentation consists of sample regions (shown as cross-hatched) within the complete field of the image data. In another embodiment, the sampled regions can be based on a preloaded user template that, for example, identifies regions of interest such as a signature region and/or a bar code region, in for example, a shipping label.
In one embodiment, the segmentation process is used to identify the location of a signature in image data the might include additional elements such as dataforms including bar code dataforms, text, graphics, images and the like. In one such embodiment the generalized classifier circuit 21216 classifies the contents of each region of the segmented image data. The region containing the signature is then extracted by the signature data processing circuit 21218. In one embodiment if multiple regions are indicated as containing signature data, the signature data processing circuit 21218 analyzes the arrangement of these regions to identify the region most likely to contain the image data. In a further embodiment when multiple regions are indicated as containing signature data, the image processing and analysis circuit 21208 establishes a feedback loop where additional segmented regions are generated and analyzed until a single segmented region containing signature data is located.
Additional image processing operations which may be carried out by optical reader 100 are described in U.S. patent application Ser. No. 10/958,779, filed Oct. 5, 2004 entitled, “System And Method To Automatically Discriminate Between A Signature And A Barcode” and incorporated herein by reference in its entirety.
Various applications which may be carried out by any of the optical readers 100 that have been described herein have been described with reference to FIGS. 10, 11, 12 a and 12 b. Another application which can be carried out with any optical reader 100 described herein is described with reference to FIGS. 13 a-13 e. In FIG. 13 a a motor vehicle 1282 is shown which may be a delivery vehicle or a passenger vehicle. Vehicle 1282 has a license plate 1314, a vehicle identification number (VIN) sticker 1306, typically located on the driver's side door jam. The VIN sticker 1306 carries a printed VIN number 1308 and a bar code symbol 1310. A VIN number is an alphanumeric unique vehicle identification number assigned at the time of manufacture of the vehicle. Vehicle 1282 may further include a VIN plate 1314 (FIG. 13 c) carrying the characters of the VIN number etched on a metal plate and located under the vehicle windshield 1351, and a vehicle registration sticker 1320. Vehicle 1282 has a plurality of machine readable vehicle identifiers. Specifically, the characters of license plate 1284 can be OCR decoded by optical reader. Further, VIN sticker 1308 has a VIN bar code 1310 and registration sticker 1320 which may include a plurality of bar code symbols 1322, 1324 encoding the vehicle registration number and possibly redundantly encoding the VIN number of vehicle 1282. The characters etched on VIN plate 1314 can also be subject to OCR decoding by optical reader 100. Further, the VIN characters of VIN sticker 1306 can be subject to OCR decoding by optical reader 100. It may be advantageous to utilize an optical reader including light polarizing pixels 250P having light polarizing filter elements 261 when reading VIN plate 1314 given that specular reflection read conditions are more prevalent when decoding indicia encoded by etching on metal surface.
In an application for utilizing optical reader 100 relative to vehicle 1282, several identifiers of vehicle 1282 may be decoded and several color pictures of vehicle 1282 may be taken. The decoded message data together with the color picture data may then be uploaded to a remote server 184 (FIG. 10) which archives and creates accessible web pages containing reports summarizing the identifier and picture information. In one application LAN 170 (FIG. 10) is a LAN at an automobile insurance claim center, LAN 185 is a distant data archiving center operated by the automobile insurance provider and LAN 2170 is a LAN apart from LAN 170 and LAN 185 and may be located, e.g., at a claim center of the insurance provider other than the claim center in which LAN 170 is located.
Optical reader 100 may be configured so that when an operator actuates a designated user interface control button such as button 3158 (FIG. 9 b) an auto insurance application form 1362 is displayed on display 504 which aids an operator of optical reader 100 in entering data into reader 100. Form 1362 first prompts an operator to read several machine readable identifiers of vehicle 1282. Form 1362 prompts an operator to read VIN bar code symbol 1310, then characters of VIN plate 1314, then the first registration sticker bar code symbol 1310, then the second registration sticker bar code symbol 1324, then the character of the license plate 1284. The text corresponding to each identifier may be highlighted when data corresponding to the identifier is read. When data corresponding to identifier decode section 1363 of form 1362 is being entered, optical reader 100 is in a decode mode of operation such that actuation of trigger 216 causes optical reader 100 to obtain a decode frame at step 1204 and transfer the decode frame to decode circuit 1702. The decode frame may contain monochrome image data read from a hybrid monochrome image sensor array 182, 182A. Where optical reader 100 has separate picture taking and decoding imaging assemblies as described in connection with FIGS. 17 a-17 g, the decode frame at step 1204 is obtained by actuation of the imaging assembly within block 598 (FIG. 17 a). When entry of decoded vehicle identifier information is complete, an operator toggles to line 1365 and clicks an appropriate key of keyboard 508 to indicate that identifier decoding is complete. Form 1362 then prompts an operator to take pictures of vehicle 1282 for purposes of making a record of the damage to vehicle 1282. The inventor discovered that the incorporation of color filter elements into an image sensor array 182 of optical reader 100 facilitates the obtaining of visual display frames of image data that accurately record damage to a vehicle. With visual display color frames of image data corresponding to vehicle 1282 being stored and/or displayed for visual display, damage to vehicle 1282 can readily be assessed by visual inspection of the visual display frames when displayed on a display 504, 1504. When damage records are recorded with color image data, the amount of paint scratched from a vehicle, for example, can readily be assessed by visual inspection. Section 1364 of display form 1362 prompts an operator to take several color pictures of vehicle. When picture entry section 1364 of form 1362 is being executed, optical reader 100 is in a picture taking mode such that actuation of trigger 216 causes a visual display frame of image data to be obtained at step 1404 (FIG. 14 c). The visual display frame of image data may be output to e.g., a storage device and/or a display device. When data corresponding to form section 1364 is being entered, an operator may use optical reader 100 to take several color pictures of damaged area 1370 of vehicle 1282. While executing obtain step 1404, control circuit 552 may selectively read out color image data from color sensitive pixels 250C as described herein and possibly utilize monochrome image data for enhancement of the information content of the color image data. Where optical reader 100 includes a pair of imaging assemblies as described in connection with FIGS. 17 a-17 g, control circuit 552 at step 1404 may actuate color image sensor array 182D for execution of obtain step 1404. When an operator inputs a confirmation that all necessary pictures of vehicle 1282 have been taken by toggling to line 1367 and clicking an appropriate key of keyboard 508, control circuit 552, which may be incorporated in hand held housing 101, may format obtained visual display color frames of image data in one or more suitably image file formats, (e.g., .BMP, .TIFF, .PDF, .JPG, .GIF) assemble all the collected decoded vehicle identifier data and all of the visual display color frames of image data corresponding to vehicle 1282 into a transaction data set, and send the transaction data set to distant remote server 184. Control circuit 552 may date/time stamp the transaction data set on sending. The File Transfer Protocol (FTP) may be utilized to send the transaction data set or another suitable file transferring protocol configured to carry associated decoded vehicle identifier data (such as decoded VIN bar code data and decode vehicle registration bar code data) and color image data. Server 184 may store the received transaction data set into a database as indicated by database 187 including similar information from other vehicles at other claim centers. Server 184 may be configured to create viewable web pages summarizing the transaction set data (e.g., the date/time stamped combined VIN, registration number, license plate number and record-of damage visual display color frames of image data). These web pages may be viewed using any PC in communication with IP network, e.g., PC 172 and PC 2172.
While the present invention has necessarily been described with reference to a number of specific embodiments, it will be understood that the time, spirit, and scope of the present invention should be determined only with reference to the following claims:

Claims

We claim:

1. An optical reading device, said optical reading device comprising:

a solid state image sensor array having a plurality of pixels, the plurality of pixels being formed in a plurality of rows of pixels, wherein the solid state image sensor array includes a first subset of pixels, a second subset of pixels, and a third subset of pixels, the first subset of pixels being monochrome pixels, the second subset of pixels being color sensitive pixels, and a third subset of pixels being light polarizing pixels;

an imaging lens focusing an image onto said solid state image sensor array;

a hand held housing encapsulating said solid state image sensor array;

wherein said optical reading device is operative to read out a frame of image data from the solid state image sensor array, the frame of image data having image data corresponding to at least one of the first subset of pixels, the second subset of pixels, and the third subset of pixels.

2. The optical reading device of claim 1, wherein the optical reading device is operative so that for read out of the frame of image data, the optical reading device reads out image data from pixels of more than one of the first, second, and third subset of pixels.

3. The optical reading device of claim 1, wherein the optical reading device is operative so that for read out of the frame of image data, the optical reading device selectively addresses pixels of the first subset of pixels and selectively reads out image data from pixels of the first subset of pixels.

4. The optical reading device of claim 1, wherein the optical reading device is operative so that for read out of the frame of image data, the optical reading device selectively addresses pixels of the second subset of pixels and selectively reads out image data from pixels of the second subset of pixels.

5. The optical reading device of claim 1, wherein the optical reading device is operative so that for read out of the frame of image data, the optical reading device selectively addresses pixels of the third subset of pixels and selectively reads out image data from pixels of the third subset of pixels.

6. The optical reading device of claim 1, wherein the optical reading device is operative so that for read out of the frame of image data, the optical reading device reads out image data from pixels of more than one of the first, second, and third subset of pixels, and wherein the optical reading device is operative to selectively extract from the frame of image data image data corresponding to the third subset of pixels.

7. The optical reading device of claim 1, wherein said optical reading device includes separate reset control lines for facilitating independent reset of pixels of said first subset of pixels, said second subset of pixels, and said third subset of pixels.

8. The optical reading device of claim 1, wherein the optical reading device is operative to sense a saturation condition.

9. The optical reading device of claim 1, wherein the optical reading device is operative to sense a saturation condition by analysis of image data.

10. The optical reading device of claim 1, wherein the optical reading device includes an illumination assembly.