JP6519033B1 - Object detection device, object detection method, and design method of object detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the influence of disturbance light simply and inexpensively in the case where reflected light incident from the outside of a laser beam projected to the outside is detected using a light receiving element.
SOLUTION: A light projecting unit for projecting a laser beam to the outside, a light receiving element 43, a light receiving optical system for guiding incident light from the outside to the light receiving element 43, a light emitting timing of the laser beam, a light receiving element 43 And an object detection unit for detecting the distance to the object on the optical path of the laser beam based on the timing of the light detection signal output from the light source. A condenser lens 42 for forming an image on the upper side, and an aperture 44 disposed on the focal plane of the condenser lens 42 are provided.
[Selected figure] Figure 20

Description

The present invention relates to an object detection apparatus and an object detection method for detecting an object on the light path of a laser beam using a laser beam. The present invention also relates to a method of designing such an object detection apparatus.

BACKGROUND ART Conventionally, an object detection apparatus that detects an object on the optical path of laser light and a distance to the object by irradiating a pulse of laser light to the outside and detecting the laser light reflected and returned by the object is disclosed. Are known. Such an object detection device is called a light detection and ranging (LiDAR).
In recent years, riders have come to be used in the field of automatic driving of automobiles. In order to compensate for the shortcomings of camera sensors that are susceptible to external lighting conditions and millimeter wave radars with low resolution, and to detect relatively small obstacles under driving environments with precision, camera sensors and millimeter wave radars It is combined use etc.

  Examples of riders that can be used in the field of autonomous driving are described, for example, in US Pat. In order to capture high-resolution distance information in the field of view, the lidar described in Patent Document 1 arranges the near-infrared laser as the light source and the light detection element as the receiver as a pair on the substrate according to the measurement angle. 32 sets or 64 sets of light source-receiver pairs are used. Therefore, the cost of the device is very high.

  In addition, another rider's example is described in Non-Patent Document 1. The rider described in Non-Patent Document 1 rotates a polygon mirror having three planes with different inclination angles, and deflects the laser beam with the polygon mirror to obtain a viewing angle range of 4.5 ° in the vertical direction. The light reflected from the object is reflected on the same surface as that of the projection of the polygon mirror and guided to the light detection element for detection.

In the lidar described in Non-Patent Document 1, one light receiving element can detect reflected light from a plurality of positions in the vertical direction. However, the rider described in Non-Patent Document 1 has a problem that it is difficult to design the center of gravity because a polygon mirror having different inclination angles for each reflection surface is used, and the cost becomes high in this respect. In addition, if the polygon mirror continues to rotate at high speed for a long time, the bearing generates heat and wear due to friction, and there is a problem in terms of maintainability when used for a long time.
A rider using a rotating mirror is also described in Non-Patent Document 2, but this document does not describe the configuration of the rider in detail.

U.S. Patent No. 8767190

Cristiano Niclass, et al., “A 100-m Range 10-Frame / s 340 x 96-Pixel Time-of-FlightDepth Sensor in 0.18-μm CMOS”, IEEE JOURNAL OF SOLID-STATE CIRCUITS, Institute of Electrical and Electronics Engineers, FEBRUARY 2013, VOL. 48, NO. 2, p. 559-572 Naoshi Shimizu, "Redundant system to achieve level 3 and LiDAR Audi become pioneers in automatic driving," Nikkei Automotive, Nikkei BP, September 2017, p. 22-23

  By the way, in order to detect an object having a lower light reflectance at a longer distance in object detection in the lidar, the detection sensitivity of the light receiving element (light detecting element) is increased to enable detection of weaker reflected light. An approach can be considered. However, disturbance light is also incident from the light path for taking in the reflected light from the object, so if the detection sensitivity of the light receiving element is increased, not only the reflected light from the object but also the detection signal of the disturbance light becomes large. There is also a high possibility that the disturbance light is misidentified as the reflected light from the object.

Therefore, in the related art, many approaches have been taken to increase the intensity of the reflected light by increasing the output of the laser beam to be irradiated, and to relatively reduce the influence of disturbance light. However, in this approach, the apparatus becomes large and expensive in order to generate a high power laser beam, and there are problems in safety in projecting the high power laser beam on the road.
The problem of disturbance light as described above does not presuppose scanning by a laser beam, but occurs similarly when detecting an object in only one direction.

  The present invention has been made in view of such circumstances, and it is simple and inexpensive to detect disturbance light of a laser beam projected to the outside, which is reflected from the outside using a light receiving element. Intended to reduce the impact.

In order to achieve the above object, an object detection apparatus according to the present invention diverges in the arrangement direction of the plurality of light emitting points from a laser light source in which a plurality of light emitting points are arrayed and laser light output by the plurality of light emitting points. A lens for generating a laser beam having an angle, a light receiving element which is one silicon photomultiplier (SiPM) corresponding to the laser beam, and the laser beam is projected to the outside, and the same optical axis as the light projection An optical system for guiding incident light from the outside and guiding it to the light receiving element, a scanning unit for periodically changing the projection direction of the laser beam by the light projection unit, and a projection timing of the laser beam Object detection for detecting the distance to the object on the optical path of the laser beam and the direction in which the object is present, based on the light emission direction and the light detection signal output from the light receiving element An optical element, the optical system separating the incident light from the projection light path of the laser beam, and the incident light separated by the optical element on a predetermined focal plane A focusing lens for forming an image, and an aperture disposed on the focal plane of the focusing lens, wherein the divergence angle is α, and the diameter of the light passing region of the aperture in the direction corresponding to the divergence angle Where D is the distance from the focusing lens to the aperture, and β = arctan (D / d), where α ≦ β.

In such an object detection apparatus , it is preferable that 1 ≦ β / α ≦ 3.
Furthermore, it is preferable that the light passing through the condensing lens be incident on the entire light receiving surface of the silicon photomultiplier.
Furthermore, a light diffusion member may be provided between the aperture and the light receiving element.

Further, according to the object detection method of the present invention, a laser beam emitted by a laser light source in which a plurality of light emitting points are arranged passes a lens to generate a laser beam having a diverging angle in the arrangement direction of the plurality of light emitting points. The laser beam is projected to the outside while periodically changing its projection direction by the scanning unit, and the incident light from the outside is guided with the same optical axis as the projection, and the optical element The incident light is separated from the projection light path of the laser beam, and the separated incident light is imaged on a predetermined focal plane by a condenser lens, and an aperture disposed on the focal plane of the condenser lens The diameter of the light passing region of the aperture in the direction corresponding to the divergence angle is D, the distance from the focusing lens to the aperture is d, β = arctan (D As α / d), α ≦ β By some aperture diaphragm the light condensed by the condenser lens to be incident light passing through the aperture on the light-receiving element is one of a silicon photomultiplier corresponding to the laser beam (SiPM), the laser beam The distance to the object on the optical path of the laser beam and the direction in which the object is located are detected based on the light emission timing and the light emission direction of the light emission element and the timing of the light detection signal output from the light receiving element.
In the method of designing an object detection apparatus according to the present invention, the laser light source in which a plurality of light emitting points are arranged and the laser light output from the plurality of light emitting points have a divergence angle in the arrangement direction of the plurality of light emitting points. A lens for generating a laser beam , a light receiving element which is one silicon photomultiplier (SiPM) corresponding to the laser beam, and the laser beam is projected to the outside, and the same optical axis as the projection is applied to the outside An optical system for guiding incident light incident from the light source to the light receiving element, a scanning unit for periodically changing the light projection direction of the laser beam by the light emitting unit, light projection timing and light emission of the laser beam An object detection unit for detecting the distance to the object on the optical path of the laser beam and the direction in which the object is located based on the direction and the timing of the light detection signal output from the light receiving element An optical element for separating the incident light from the projection light path of the laser beam; a condenser lens for forming the incident light separated by the optical element on a predetermined focal plane; A design method for designing an object detection device comprising an aperture arranged on a focal plane of a lens, the method comprising: β based on the size α of the divergence angle and the distance d from the focusing lens to the aperture As arctan (D / d), the diameter D in the direction corresponding to the divergence angle of the light transmission region of the aperture is determined so as to satisfy α ≦ β.
In such a method of designing an object detection apparatus, the diameter D may be set to satisfy 1 ≦ β / α ≦ 3.

  The present invention also provides another object detection apparatus, control method and program therefor for the purpose of realizing scanning with a periodic variation in the projection direction of a laser beam with a small size and high durability. Do.

  This object detection apparatus includes a light emitting unit that emits a laser beam to the outside, a scanning unit that periodically changes the light projection direction of the laser beam by the light emitting unit, a light receiving element, and incident light from the outside. The distance to the object on the optical path of the laser beam, based on the light receiving optical system leading to the light receiving element, the light projection timing and direction of the laser beam, and the timing of the light detection signal output from the light receiving element An object detection apparatus comprising: an object detection unit for detecting a direction in which the object is present, wherein the scanning unit is a torsion spring formed of a plate material having a fold, and a linear shape formed by the fold A torsion spring fixed to the support member, a mirror fixed to one surface of the torsion spring and reflecting the laser beam, and the torsion spring so as to straddle the projection. A permanent magnet having an N pole on one side across the projection and an S pole on the other side, a drive coil disposed on the opposite side of the permanent magnet from the torsion spring, and The mirror includes: a sensing coil having a core material common to the drive coil, a magnetic body surrounding the drive coil, and a drive unit for applying a drive signal having a voltage or current periodically changed to the drive coil, It reciprocates according to the application of the drive signal.

In such an object detection apparatus, the cross-sectional shape of the protrusion may be V-shaped.
Furthermore, it is preferable that one end of the axis of the drive coil is opposed to the midpoint between the S pole and the N pole of the permanent magnet.
Further, the end of the magnetic body facing the N pole and the S pole of the permanent magnet is the N pole when viewed from the end of the axis of the drive coil facing the permanent magnet along the axis. It is preferable to be at a position farther than the center line of the permanent magnet connecting the two and the S pole.
Furthermore, a detection unit that detects a voltage or current generated in the sensing coil, and a cycle that controls the blinking cycle of the laser beam emitted by the light projection unit according to the level of the voltage or current detected by the detection unit. It is good to provide a control part.
Furthermore, when the level of the voltage or current detected by the detection unit is a first level indicating that the mirror is near the center of the path of the reciprocating drive, the cycle control unit causes the mirror to move back and forth It is preferable to shorten the blink cycle as compared to the case where the second level indicates that the drive path is near the end.

A control method according to the present invention is a control method for controlling any one of the above object detection devices, which detects a voltage or current generated in the sensing coil and responds to the level of the detected voltage or current. And controlling the blinking period of the laser beam emitted by the light emitting unit.
In such a control method, depending on the level of the voltage or current generated in the sensing coil, the level of the voltage or current is a first level indicating that the mirror is near the center of the path of the reciprocating drive. In some cases, it is preferable to control the blinking period of the laser beam so as to shorten the blinking period as compared with the case where the mirror is at the second level indicating that the mirror is near the end of the reciprocating drive path. .
Also, a program according to the present invention is a program for causing a processor to control hardware to execute any of the control methods described above.

  Another object of the present invention is to realize a mover having a reciprocally driven mirror, which can be used for scanning to periodically change the projection direction of a laser beam, with a configuration that can be mass-produced at low cost. The invention also provides a mover and a method of manufacturing the same.

The mover is a torsion spring formed of a plate material having a fold, and the protrusion is a linear protrusion formed by the fold and the protrusion so as to straddle the protrusion around the center of the protrusion. A torsion spring including a flat portion integrally formed with the first portion, and a first spacer of the same height as the protrusion fixed to the first surface of the flat portion on the side where the protrusion protrudes. A first member fixed to the side opposite to the flat surface portion of the first spacer, and a second member fixed to the second surface opposite to the first surface of the flat surface portion; One of the member and the second member is a mirror, and the other is a magnet, and the magnet is fixed so as to straddle the projection, and has an N pole on one side across the projection and an S pole on the other side. Is located.
It is preferable that such a mover have a second spacer between the flat portion and the second member, and the second member be fixed to the flat portion via the second spacer.

  Further, the method of manufacturing the mover is a torsion spring formed of a plate material having a fold, and straddles the linear protrusion formed by the fold and the protrusion in the vicinity of the center of the protrusion. In a torsion spring including a flat portion integrally formed with the protrusion, a first spacer having the same height as the protrusion is provided on a first surface of the flat portion on the side where the protrusion protrudes. In the first step of fixing so as to be able to maintain fixation even during the heat treatment of the third step by adhesion or pressure bonding, and after the first step, via the adhesive layer melted by heating on the first spacer In a second step, a first member is stacked, and a second member is stacked on the second surface opposite to the first surface of the flat portion via an adhesive layer which is melted by heating. And one of the first member and the second member is a mirror, and the other is a mirror. The magnet is a stone, and the magnet straddles the protrusion, and is stacked in the second step such that the N pole is positioned on one side across the protrusion and the S pole is positioned on the other side, and the second step A heat treatment is performed on the formed laminate, and the third step of fixing the first member to the first spacer and fixing the second member to the flat portion is provided.

  In the manufacturing method of such a mover, in the first step, the second spacer can be maintained fixed during the heat treatment in the third step by adhesion or pressure bonding to the second surface of the flat portion. In the second step, the second member is laminated on the surface of the second spacer opposite to the flat portion via the adhesive layer melted by the heating, In the third step, the second member may be fixed to the flat portion via the second spacer.

  Further, a plurality of the torsion springs and the first spacers are prepared in a state of being connected in a plurality and connected in a planar manner, and in the first step, the plurality of torsion springs and the plurality of first spacers Are collectively fixed in a connected state, and in the second step, the laminate is formed for each of the plurality of torsion springs, and in the third step, collectively in the plurality of laminates. The heat treatment may be performed to form a plurality of coupled movers.

  Alternatively, a plurality of the torsion springs, the first spacers, and the second spacers may be prepared in a plurality of connected and arranged in a planar manner, and the plurality of torsion springs and the plurality of torsion springs may be prepared in the first step. The plurality of first spacers and the plurality of second spacers are collectively fixed in a connected state, and the laminate is formed for each of the plurality of torsion springs in the second step. In the third step, the plurality of stacks may be collectively subjected to the heat treatment to form a plurality of coupled movers.

  Further, the invention described above as an apparatus, method, program or the like can be implemented not only in the aspect described above but also in any form such as an apparatus, system, method, program, recording medium recording the program, and the like.

  According to the configuration of the present invention as described above, the influence of disturbance light can be reduced easily and inexpensively when using the light receiving element to detect the reflected light of the laser beam projected to the outside incident from the outside. Can.

It is a block diagram which divides and shows the main components of object detection device 10 which is one embodiment of this invention paying attention to the function. FIG. 6 is a diagram for describing the principle of object detection in the object detection device 10; FIG. 2 is an exploded perspective view showing the structure of main components of the object detection device 10; FIG. 1 is a perspective view showing the appearance of an object detection apparatus 10; FIG. 5 is a view showing the general appearance and arrangement of the actuators 300 and 380 in an enlarged manner as compared with FIG. 3; It is a disassembled perspective view which shows the structure of the components which comprise the actuator 300, and the outline of the assembly process. FIG. 7 is an exploded perspective view showing the structure of parts constituting a mover 320 of the actuator 300. FIG. 7 is a cross-sectional view of a cross-section in a plane indicated by an alternate long and short dash line of the actuator 300 illustrated in (d) of FIG. FIG. 8B is a cross-sectional view corresponding to FIG. 8A, showing a configuration of a modification of the actuator 300. It is a disassembled perspective view which shows the structure of the components which comprise the needle | mover 330, and the outline of the assembly process. FIG. 10 is a cross-sectional view of a cross section in a plane indicated by an alternate long and short dash line of the mover 330 illustrated in (c) of FIG. It is a figure which shows the example of the laminated body which laminated | stacked and fixed in the state in which the torsion spring 331, the 1st spacer 332, and the 2nd spacer 333 were mutually connected and planarly arranged in multiple numbers, respectively. It is a graph which shows the relationship between the scanning angle of the mirror 301, and the absolute value of a scanning angular velocity. FIG. 7 is a diagram showing an example of a drive signal of the LD module 21. FIG. 14 is a diagram showing an example of a spot by the outgoing light L2 formed on a scanning line when the drive signal of FIG. 13 is used. FIG. 7 is a diagram showing a configuration of a control circuit for controlling a pulse interval of a drive signal of the LD module 21 together with circuits in the periphery thereof. It is a figure which shows the example of the drive signal of LD module 21 produced | generated by the circuit of FIG. FIG. 17 is a view showing an example of a spot by the outgoing light L2 formed on a scanning line when the drive signal of FIG. 16 is used. FIG. 3 is a view schematically showing an optical path of a laser beam emitted from the light emitting unit 20. It is a figure which shows the optical path of condensing of the return light L4 by the condensing lens 42 in case there is no aperture 44. FIG. It is a figure which shows the optical path of condensing of the return light L4 by the condensing lens 42 in case the aperture 44 exists. It is a figure which shows arrangement | positioning of the light transmission area | region of the aperture 44. FIG. It is a figure for demonstrating the effect of the aperture 44. FIG. FIG. 16 is another view for explaining the effect of the aperture 44. It is a figure corresponding to FIG. 20 which shows the optical path of condensing of the return light L4 by the condensing lens 42 at the time of providing the light-diffusion member 46. As shown in FIG.

Embodiments of the present invention will be described with reference to the drawings.
[1. Overall Configuration of Object Detection Device (FIGS. 1 to 4)]
First, the overall configuration of an object detection apparatus according to an embodiment of the present invention will be described by using FIG. 1 and FIG. FIG. 1 is a block diagram showing the main components of the object detection apparatus, focusing on its functions. FIG. 2 is a diagram for explaining the principle of object detection in the object detection apparatus.

  An object detection apparatus 10 according to an embodiment of the present invention projects a laser beam to the outside and detects a laser beam reflected and returned by an external object, and the light emission timing and the detection timing of the reflected light And a device for detecting the distance to an object on the optical path of the laser beam and the direction in which the object is located. As shown in FIG. 1, the object detection apparatus 10 includes a light emitting unit 20, a scanning unit 30, a light receiving unit 40, a front end circuit 51, a TDC (Time-to-Digital Converter) 52, and a processor. 53, an input / output unit 54 is provided.

Among them, the light projecting unit 20 is a module for projecting a laser beam to the outside, and includes an LD (laser diode) module 21, a laser driving circuit 22, and a light projecting optical system 23.
The LD module 21 is a light emitting unit that outputs a laser beam according to a drive signal applied from the laser drive circuit 22. Here, although what has a plurality of light emitting points is used to increase the output intensity, the number of light emitting points may be one. There are no particular restrictions on the wavelength of the laser light, but it is conceivable to use, for example, near infrared light laser light.
The laser drive circuit 22 is a circuit for generating a drive signal for lighting the LD module 21 at a timing according to the parameters supplied from the processor 53 and applying the drive signal to the LD module 21. Lighting of the LD module 21 is intermittently performed by a pulse wave.

The projection optical system 23 is an optical system for converting the laser beam output from the LD module 21 into a beam of parallel light, and in this embodiment, the focal point is located at the center of a plurality of light emitting points included in the LD module 21. A collimating lens with a convex lens is used.
The laser beam L1 formed by the light projecting optical system 23 passes through the through hole 41a of the mirror 41 of the light receiving unit, is reflected by the mirror 31 of the scanning unit 30, and is output to the outside of the object detection device 10 as the emitted light L2. Output.

  Next, the scanning unit 30 is a module for deflecting the laser beam output by the light emitting unit 20 to scan the inside of a predetermined field of view (FOV: Field of View) 70, and an actuator 32 having a mirror 31. Equipped with The actuator 32 periodically changes the projection direction of the laser beam by periodically changing the direction of the mirror 31 provided on the optical path of the laser beam.

In addition, although only one actuator 32 is shown in FIG. 1, the actuator 32 actually comprises two actuators 300 and 380 for swinging the mirror about different axes as shown in FIGS. 3 and 5. Be done. Then, the actuator 300 takes charge of scanning in the main scanning direction to form the main scanning direction (Horizontal) scanning line 71a, and the actuator 380 changes the direction of the mirror at the end of the scanning in the main scanning direction The vertical scanning line 71b is formed, and the scanning position in the sub-scanning direction is adjusted.
In addition, since the LD module 21 is intermittently turned on, the scanning line 71 is not a continuous line but a set of beam spots in practice.

  Next, the light receiving unit 40 is a module for detecting light incident from the outside of the object detection device 10, and includes a mirror 41, a condensing lens 42, a light receiving element 43, and an aperture 44. The light desired to be detected by the light receiving unit 40 is a laser beam which is projected from the object detection device 10 and reflected by an external object and returned. The laser beam is diffusely reflected at the object plane, but only the component reflected in the opposite direction to the light path at the time of light emission is returned to the object detection apparatus 10 as return light L3. The return light L3 travels in the reverse direction substantially the same path as the outgoing light L2 and reaches the mirror 41 as the return light L4.

  The mirror 41 is a fixed mirror for guiding the return light L4 to the light receiving element 43 as well as having a through hole 41a for passing the laser beam output from the light emitting unit 20. At the position of the mirror 41, the return light L4 spreads more than the laser beam L1. Therefore, the component hit the mirror 41 in a range wider than the through hole 41a and the component corresponding to the position other than the through hole 41a is reflected toward the light receiving element 43 Be done.

The condenser lens 42 is a lens that condenses the return light L4 reflected by the mirror 41 and forms an image on a predetermined focal plane.
The light receiving element 43 is a light detecting element that outputs a detection signal according to the intensity of the light striking the predetermined light receiving surface. In this embodiment, a silicon photomultiplier (SiPM) is used as a light receiving element. This point will be described in detail later.
The aperture 44 is disposed on the focal plane of the condenser lens 42 and blocks light other than the opening. The detailed configuration of the aperture 44 and the meaning thereof will also be described later.
Among the above, the mirror 41, the condenser lens 42 and the aperture 44 constitute a light receiving optical system.

Next, the front end circuit 51 is a circuit that shapes the detection signal output from the light receiving element 43 into a waveform suitable for timing detection in the TDC 52.
The TDC 52 corresponds to the timing t0 of the lighting pulse of the laser beam L1 to be emitted light, based on the drive signal supplied from the laser drive circuit 22 and the shaped detection signal supplied from the front end circuit 51. Is a circuit that forms a digital output indicating the time difference from the timing t1 of the pulse of the return light L4.

  Since there is a time difference between the pulse of the emitted light and the pulse of the return light by the time required for the light to reach and return to the object on the optical path, the object detection is performed based on the time difference Δt as shown in FIG. The distance s from the device 10 to the object can be determined as s = c (Δt) / 2. c is the speed of light. The above s is exactly the optical path length from the object to the light receiving element 43.

  The processor 53 is a control unit that controls the operation of each unit illustrated in FIG. It may be configured by a general-purpose computer that includes a CPU, a ROM, a RAM, and the like and executes software, or may be configured by dedicated hardware, or a combination thereof. For example, the processor 53 calculates the distance to the object based on the output signal from the TDC 52, and calculates the direction in which the object is based on the scanning timing (projecting direction of the emitted light L2) by the scanning unit 30 at the detection time of the return light. I do. Further, as will be described in detail later, control of the lighting interval of the LD module 21 in accordance with the direction of the mirror 31 in the scanning unit 30 is also performed.

  The input / output unit 54 is a module that inputs and outputs information with the outside. For the input and output of information mentioned here, wired or wireless communication with an external device, reception of operation from the user using a button, a touch panel, etc., a user using a display, a lamp, a speaker, a vibrator, etc. Including the presentation of information to The information to be output to the outside by the input / output unit 54 includes, for example, information related to the detected object (even for raw data of distance and direction, it indicates that an object of a predetermined size, position, moving speed, etc. is detected based on them). Information regarding the operation state or the setting state of the object detection device 10 can be considered. As information that the input / output unit 54 should receive an input from the outside, for example, information regarding the setting of the operation of the object detection device 10 can be considered.

As a partner of the communication by the input / output unit 54, for example, an automobile equipped with an automatic driving system can be considered. If the information of the object detected by the object detection device 10 is supplied to the automatic driving system, the automatic driving system can refer to the information and plan a traveling route to avoid the detected object.
It is also conceivable to implement the present invention as a system including the object detection apparatus 10 and an apparatus such as a car, a drone, an aircraft or the like with which the object detection apparatus 10 communicates.

Next, a schematic structure of the object detection device 10 will be described using FIGS. 3 and 4. FIG. 3 is an exploded perspective view showing the structure of the main components of the object detection device, and FIG. 4 is a perspective view showing the appearance of the object detection device.
As shown in FIGS. 3 and 4, the object detection device 10 includes an exterior in which a top cover 61 and a rear cover 62 are coupled by two cover clips 63 and 63. In addition, the top cover 61 includes a window for transmitting the emitted light L2, and a protective material 64 transparent to the wavelength of the emitted light L2 is fitted to the window for preventing entry of dust.

The components shown in FIG. 1 are stored inside these housings. The actuators 32 shown in FIG. 1 are shown as two actuators: an actuator 300 in charge of scanning in the main scanning direction and an actuator 380 in charge of scanning in the sub scanning direction. The mirror 301 is a mirror that the actuator 300 comprises.
Also, although not shown in FIG. 1, the mirror 48 is an optical element that is between the mirror 41 and the condenser lens 42 and changes the direction of the return light L4. The broken line 65 indicates the field of view of the object detection device 10 (the scan range of the emitted light L2), which corresponds to the field of view 70 in FIG. Wirings between circuits and modules such as the laser drive circuit 22 and the processor 53 are omitted in FIG. 3 in order to make the drawing easy to see.
After the description of the overall configuration has been completed, the following will individually describe some of the components of the object detection apparatus 10.

[2. Swing actuator using a torsion spring (FIGS. 5 to 8B)]
Although it has already been described that the scanning unit 30 includes the actuators 300 and 380, among these, the actuator 300 has a characteristic configuration, so this point will be described next.
FIG. 5 shows the general appearance and arrangement of the actuators 300, 380 in a larger scale than FIG.

As shown in FIG. 5, the actuator 300 and the actuator 380 differ greatly in their configurations.
Since the actuator 380 is used for deflection of the outgoing light L2 in the sub-scanning direction, a high speed movement is not required, so an actuator of a type for rotating the mirror about a physical axis is used. The actuator 380 is configured by fixing the mirror 381 to the shaft 382, inserting the shaft 382 into the holder 383 and rotatably attaching it. Then, by the action of the permanent magnet and the coil disposed on the back side of the mirror 381, the mirror 381 rotates around the center of the shaft 382 as the rotation shaft 384 according to the voltage applied to the coil, and reciprocates within a predetermined angle range. Do. By adjusting the intensity of the voltage, it is also possible to stop the mirror at the desired angle within the range of motion.
Such an actuator is called a galvano mirror. In general, a configuration in which a mirror attached to the other end of the shaft is rotated by applying a force to one end of the shaft is widely used, but like the actuator 380, the position where the force is applied to the shaft and the mounting position of the mirror However, even on the same position in the longitudinal direction of the shaft, driving on the same principle is possible.

  On the other hand, since the actuator 300 is used for deflection of the outgoing light L2 in the main scanning direction, high speed movement is required, and durability capable of continuing the high speed movement for a long time is also required. Therefore, as the actuator 300, a novel actuator meeting such a purpose is used.

  Although the specific configuration will be described in detail with reference to FIGS. 6 to 8A, generally, the actuator 300 has a mirror 301, a protrusion on one surface of a torsion spring 302 having a linear protrusion, and It is fixed to straddle, and the end of the torsion spring 302 is fixed to the top yoke 314 as a support member. Then, according to the voltage applied to the coil by the action of the permanent magnet and the coil disposed on the other surface side of the torsion spring 302, the torsion spring 302 and the mirror 301 are substantially at the center of the projection of the torsion spring 302. It rotates around a rotating shaft 304 and reciprocates within a predetermined angular range.

The scanning unit 30 reflects the laser beam L1 by the mirrors 301 and 381 driven by the above actuators 300 and 380, and deflects the laser beam L1 so that the outgoing light L2 scanning the scanning line 71 shown in FIG. Can be projected to
Of course, using an actuator having the same structure as that of the actuator 300 as an actuator for performing deflection scanning in the sub scanning direction is not disturbed.

  Next, the structure and operation principle of the actuator 300 will be described in more detail with reference to FIGS. 6 to 8A. FIG. 6 is an exploded perspective view showing the structure of parts constituting the actuator 300 and an outline of its assembly process, including a perspective view of the actuator 300 completed in its final process. FIG. 7 is an exploded perspective view showing the structure of parts constituting the mover 320 of the actuator 300. As shown in FIG. FIG. 8A is a cross-sectional view of a cross section in a plane indicated by an alternate long and short dash line of the actuator 300 illustrated in (d) of FIG. However, in order to make a figure legible, illustration of coil assembly 313 is omitted in Drawing 8A, and how to wind a coil is shown typically.

The actuator 300 includes a core yoke 311, a frame yoke 312, a coil assembly 313, a top yoke 314, and a mover 320, as shown in FIG. 6A.
Among these, the frame yoke 312 and the top yoke 314 form an outer package made of a magnetic material surrounding the coil. The frame yoke 312 and the top yoke 314 are fixed so as to hold the coil assembly 313 inside by four screws 315 passing through the four sets of screw holes 312 b and 314 b.

The coil assembly 313 is obtained by winding two coils of a drive coil 316 and a detection coil 317 shown in FIG. 8A around a nonmagnetic bobbin 313a and covering the outside with a protective cover 313c. An insertion hole 313 b for passing the core portion 311 a is provided inside the bobbin 313 a. In addition, the protective cover 313 c is provided with a terminal for applying a drive signal to the drive coil 316 and a terminal for outputting a signal generated in the sensing coil 317 at a position not covered by the exterior.
The core yoke 311 includes a core portion 311 a of ferromagnetic material, which is a core of the drive coil 316 and the sensing coil 317.

  In each of these parts, as shown in FIG. 6B, the core portion 311a of the core yoke 311 is inserted into the insertion hole 312a of the frame yoke 312, and then in the insertion hole 313b of the coil assembly 313 as shown in FIG. The core portion 311a is inserted to position the coil assembly 313, and thereafter, as shown in (d), the top yoke 314 and the frame yoke 312 are fixed by screws 314 and integrated.

At this time, the core portion 311a is fixed to the frame yoke 312 in the steps (a) to (b), and the coil assembly 313 is fixed to the core portion 311a (and the frame yoke 312) in the steps (b) to (c). Fix it. This fixing is performed by using screws, welding, or bonding (not shown), or by inserting the member on the insertion side slightly larger than the space on the receiving side and pressing it into the receiving position, or a combination of these. It is possible to do.
In addition, in (b) and (c) of FIG. 6, illustration of the needle | mover 320 is abbreviate | omitted on account of space.

Further, as shown in FIG. 7, the mover 320 includes a permanent magnet 321 and a connection holder 323 in addition to the mirror 301 and the torsion spring 302.
Among them, the torsion spring 302 is a spring formed by bending a metal plate by pressing, folding or the like, and is provided with a linear protrusion 302 c having a V-shaped cross section by its fold. In addition, flat portions 302b are provided in the vicinity of the center of the protruding portion 302c so as to cross the protruding portion 302c, and flat portions protruding on both sides so as to cross the protruding portion 302c. And 302a. The projection 302c and the flat portions 302a and 302b are all integral, and a single plate-like member is bent to form these portions, so that the torsion spring 302 having sufficient strength can be manufactured at low cost. It can be formed.

Further, the flat portions 302a and the flat portions 302b at both ends are all located on the same plane in the natural state. However, when a force rotating around the protrusion 302c is applied to the flat portion 302b with the flat portions 302a at both ends fixed on the same plane, the protrusion 302c is twisted, and the flat portion 302b centers the protrusion 302c. Move to the When the application of force is stopped, the resilient force of the spring cancels the twist of the protrusion 302c, and the flat portion 302b returns to the same plane as the flat portion 302a.
The permanent magnet 321 is fixed on the surface of the flat portion 302b opposite to the protrusion 302c such that the N pole 321n is located on one side across the protrusion and the S pole 321s is located on the other side. The positions of the N pole 321 n and the S pole 321 s do not matter even if they are reverse to those in the figure.

Fixing between the permanent magnet 321 and the flat surface portion 302b is performed by sandwiching the permanent magnet 321 and the flat surface portion 302b from outside with the connection holder 323 as shown in FIG. 8A. Then, the connection holder 323, the permanent magnet 321, and the flat portion 302b are fixed to each other by bonding or the like. It is also conceivable to fix by the elastic force using the connection holder 323 which has elasticity. A combination of these may be used. It is also conceivable to form the resin connection holder 323 integrally with the torsion spring 302 on the torsion spring 302 by outsert molding.
FIG. 8A is a cross-sectional view of a plane perpendicular to the longitudinal direction of the protrusion 302c, which passes near the center of the flat portion 302b.

The mirror 301 is fixed to the surface of the connection holder 323 opposite to the flat portion 302 b. This fixing is performed by adhesion. Although any adhesive may be used, an adhesive having less curing shrinkage is desirable.
The mover 320 described above is fixed to the mover holding portion 314a of the top yoke 314 in the process between (c) and (d) in FIG. 6 after the members shown in FIG. 7 are assembled in advance. Do. This fixing is performed by screwing the flat portion 302a to the mover holding portion 314a with a screw (not shown), bonding or welding the flat portion 302a and the mover holding portion 314a, or the flat portion The insertion can be performed by any method such as inserting the slit 302 a into the slit provided in the mover holding portion 314 a.

  With the mover 320 fixed to the top yoke 314, the flat portion 302 b of the torsion spring 302 and the permanent magnet 321 face the coil assembly 313 through the opening 314 c of the top yoke 314. More specifically, as shown in FIG. 8A, one end of the shaft of the drive coil 316 provided in the coil assembly 313 faces the midpoint between the N pole 321 n and the S pole 321 s of the permanent magnet 321. When viewed from the permanent magnet 321, the drive coil 316 is disposed on the opposite side of the torsion spring 302.

In this state, when the drive coil 316 is energized, for example, the end facing the permanent magnet 321 has an N pole, the S pole 321s of the permanent magnet 321 is attracted to the drive coil 316, and the N pole 321n is The repulsive force acts on the permanent magnet 321 to rotate clockwise as viewed in FIG. 8A. The force is transmitted to the flat portion 302b of the torsion spring 302, and the torsion spring 302 is rotated clockwise about an imaginary rotation axis 304 near the center of the cross section of the projection 302c and twisted. Along with this, the mirror 301 fixed to the flat portion 302 b also rotates clockwise about the rotation axis 304.
Then, the rotation stops at a position where the magnetic force generated between the drive coil 316 and the permanent magnet 321 and the restoring force of the torsion spring 302 are balanced. By changing the strength of the current supplied to the drive coil 316, the speed and stop position of this rotation can be adjusted.

  Next, with the permanent magnet 321 and the mirror 301 rotated clockwise to an appropriate position, when the current supply direction to the drive coil 316 is reversed, the end on the side facing the permanent magnet 321 becomes the S pole, This time, the N pole 321n of the permanent magnet 321 is attracted to the drive coil 316, the S pole 321s repels the drive coil 316, and the permanent magnet 321 exerts a force to rotate counterclockwise as viewed in FIG. 8A. . The force is transmitted to the flat portion 302b of the torsion spring 302 as in the case of the clockwise rotation, and the torsion spring 302 rotates counterclockwise around the rotation axis 304 and twists in the opposite direction. Along with this, the mirror 301 fixed to the flat portion 302 b also rotates counterclockwise around the rotation axis 304.

  Periodically reversing the direction of the voltage or current of the drive signal applied to the drive coil 316 causes the mirror 301 to alternately perform the above-mentioned clockwise and counterclockwise rotations, as indicated by the arrow V, and the rotation shaft A reciprocation can be made to rotate around 304 in a predetermined angular range. That is, the mirror 301 can be rocked on a predetermined movement path. By this, it is possible to realize the periodic deflection of the laser beam L1 necessary for scanning in the main scanning direction described with reference to FIG.

  In consideration of the life of the torsion spring 302, it is desirable that the range of oscillation be symmetrical with respect to the natural state. But this is not essential. For example, by periodically switching on and off of the voltage applied to the drive coil 316, it is possible to perform oscillation within a predetermined range in which the position near the natural state is one end. By periodically changing the voltage or current applied to the drive coil 316 within an appropriate range, the mirror 301 can be swung in an arbitrary swing range within the movable range of the torsion spring 302.

In any case, in this actuator 300, although the mover 320 is fixed at its end to the top yoke 314, the portion near the flat portion 302b which is actually moved floats in the air, so that it can No friction occurs, and even if used for a long time continuously, heat generation and wear are less likely to occur. Therefore, high durability can be obtained.
Further, since the coil assembly 313 is surrounded by the top yoke 314 and the frame yoke 312 of magnetic material, leakage of the magnetic force generated in the drive coil 316 can be prevented, and high drive efficiency can be obtained. However, providing such a magnetic enclosure is not essential.

Further, as shown in FIGS. 6 and 8A, the mover holding portion 314 a of the top yoke 314 is thinner than the other portions of the top yoke 314. This is because the permanent magnet 321 is positioned inside the exterior formed of the top yoke and the frame yoke 312, and the magnetic force generated in the drive coil 316 is transmitted to the permanent magnet 321 without leaking.
In order not to leak the magnetic force generated in the drive coil 316, the end of the sheath made of a magnetic body, which is opposed to the N pole 321n and the S pole 321s of the permanent magnet 321, is one end that faces the permanent magnet 321 of the shaft of the drive coil 316. Viewed from the direction along the axis (vertical direction in FIG. 8A), it is at a position farther than the center line (indicated by reference numeral 321x in FIG. 8A) of the permanent magnet 321 connecting the N pole 321 n and the S pole 321 s. It is good.

  In this embodiment, the magnetic force can be reduced by providing the opening 314 c of the top yoke 314 with a protrusion 314 d extending in the direction from the both sides toward the mover 320 and away from the drive coil 316 (upper direction in FIG. 8A). The structure is realized to prevent leakage. With this structure, a large rotational moment can be applied from the drive coil 316 to the mover 320, and the swing speed of the mirror 301 can be increased and / or the power consumption can be reduced.

When the mover holding portion 314a is thin as shown in FIG. 8A, the mirror 301 is close to the top yoke 314, so that the movable range of the mirror 301 can be restricted by the interference between the mirror 301 and the top yoke 314. There is sex.
In order to cope with this point, as shown in FIG. 8B, it is conceivable to make the mover holding portion 314a thicker than the other portions and to separate the mirror 301 from the top yoke 314. In this configuration, the permanent magnet 321 may protrude outside the top yoke 314, which may cause a magnetic leakage. However, even in this case, as shown in FIG. 8B, if the protrusion 314d is formed such that its end is positioned above the center line 321x in the figure, magnetic leakage is prevented and the rocking speed is reduced. Speeding up and / or reduction of power consumption can be achieved.

The material of the torsion spring 302 may be, for example, stainless steel or phosphor bronze, but any other material capable of forming an elastic spring can be adopted. Also, the reason why the cross section of the protrusion 302c is V-shaped is that it has been found that a large spring constant can be obtained by the simulation of the inventors, thereby increasing the resonance frequency of the torsion spring 302. is there. A high resonant frequency is desirable, as a large scan angle can be achieved with less drive power.
However, the shape of the cross section is not limited to the V-shape, and if it can function as a torsion spring, the cross-section may be an n-shape, a U-shape, an M-shape, a W-shape or an opening There may be other shapes, such as no air core thin wall closed cross section.

In addition, the structure which has such linear protrusion part 302c can make rigidity of the direction orthogonal to a rotating shaft high compared with the torsion spring of planar structure. This rigidity is very useful for stable scanning in a constantly vibrating environment such as in a car and for ensuring the durability of the rocking portion.
Moreover, the torsion spring which has the projection part 302c is three-dimensional shape, and the thickness as a whole is large. For this reason, although it is easy to bend and form a plate material, it is possible to form a torsion spring having a projection 302c with a sufficient height in a wafer process using the technology of MEMS (Micro Electro Mechanical Systems). ,Have difficulty.

  In the example of FIG. 8A, the drive coil 316 is disposed in a direction perpendicular to the flat portion 302b in the natural state, but one end of the shaft is a midpoint between the N pole 321n of the permanent magnet 321 and the S pole 321s. And the orientation is not limited to that shown in FIG. 8A. For example, even if the axis is arranged in parallel with the protrusion 302c, the swing of the mirror 301 similar to the case of the configuration of FIG. 8A is possible.

Further, it is not essential to accommodate the drive coil 316 in the coil assembly 313 or to wind it on a bobbin, and direct winding on the core portion 311a is not hindered.
The sensing coil 317 is provided to adjust the lighting timing of the laser beam L1, which will be described later with reference to FIGS. 9 to 15, and is unnecessary if this adjustment is not performed.

Moreover, in the example shown to FIG. 8A and FIG. 8B, although the projection part 302c of the torsion spring 302 protruded to the mirror 301 side, you may project to the permanent magnet 321 side conversely. That is, the permanent magnet 321 may be provided on the surface of the flat portion 302b on the side where the protrusion 302c protrudes, via a holder similar to the connection holder 323, and the mirror 301 may be provided on the opposite surface. Also in this configuration, as in the case of the configuration described with reference to FIGS. 8A and 8B, the mirror 301 can be swung about a rotation axis located substantially at the center of the protrusion 302c.
In addition to the above, using the electromagnet that is energized when driving the mirror in place of the permanent magnet 321 is not hindered. However, the permanent magnet 321 is preferable in that the structure is simple, assembly errors are less likely to occur, and unnecessary noise is not generated.

[3. Another configuration example of the mover provided in the swing actuator and a method of manufacturing the same (FIGS. 9 to 11).
Next, another configuration example of the mover usable in the actuator 300 described above and a method of manufacturing the same will be described. The mover 330 described in this section has a configuration suitable for mass production.

FIG. 9 is an exploded perspective view showing the structure of parts constituting the mover 330 and an outline of its assembly process, including the perspective view of the mover 330 completed in its final step. FIG. 10 is a cross-sectional view of the cross section in the plane indicated by the alternate long and short dash line of the mover 330 shown in (c) of FIG. 9 as viewed in the arrow N direction.
As shown in FIG. 9A, the mover 330 includes a torsion spring 331, a first spacer 332, a second spacer 333, a mirror 301, and a permanent magnet 321. The mirror 301 and the permanent magnet 321 are equivalent to those constituting the mover 320 shown in FIG.

  The torsion spring 331 also has a flat portion 331 b and a projection 331 c similar to the torsion spring 302 constituting the mover 320. However, the flat portions 331a provided at both ends of the protrusion 331c are integrally connected to each other so as to surround the outer side of the flat portion 331b. Such a torsion spring 331 can be formed by simultaneously performing punching and bending processes on a metal plate material with a press.

  The first spacer 332 mainly includes the surface of the flat portion 331 b on which the protrusion 331 c protrudes so that the mirror 301 which is the first member can be attached on the flat portion 331 b while avoiding the protrusion 331 c. 1), and is a spacer for raising the mounting position of the mirror 301 to the same height as the protrusion 331c. The spacer portion 332 b is a spacer having the same height as the protrusion 331 c which bears the lifting. The spacer portion 332 b is connected to the outer peripheral portion 332 a by a bridge 332 d.

The outer peripheral portion 332a is formed in the same shape as the flat surface portion 331a of the torsion spring 331, and includes a protrusion 332c that covers the protrusion 331c at a position corresponding to the protrusion 331c. In addition, about the outer peripheral part 332a, ensuring of space is not necessarily required. However, in the case of simultaneous production of a large number of pieces as will be described later with reference to FIG. 11, the distance between adjacent members is too long if only the spacer portion 332 b is used. Since it is difficult to form in one sheet, it is provided also as a protective material of the torsion spring 331 in order to support the bridge 332 d.
The material of the first spacer 332 is not particularly limited as long as it can fix both the torsion spring 331 and the mirror 301. There is no need to have elasticity.

  On the other hand, when the torsion spring 331 is a material not suitable for soldering, such as stainless steel, the second spacer 333 is mainly a surface (second surface) opposite to the side where the protrusion 331 c protrudes from the flat portion 331 b. The permanent magnet 321, which is the second member, is used as a base for fixing to the flat portion 331b by soldering. The spacer portion 333 b plays a role of the base. The spacer portion 333 b is connected to the outer peripheral portion 333 a by a bridge 333 d.

The outer peripheral portion 333a is also formed in the same shape as the flat surface portion 331a of the torsion spring 331, and is provided with a projection 333c at a position corresponding to the projection 331c to cover the back side of the projection 331c. The reason for providing the outer peripheral portion 333a is the same as the case of the outer peripheral portion 332a.
The material of the second spacer 333 is a material that can be fixed to the torsion spring 331 and can be soldered. For example, if the torsion spring 331 is stainless steel, phosphor bronze is suitable as the material of the second spacer.

When manufacturing the mover 330, the following process may be performed.
First, as shown in FIG. 9B, the first spacer 332 can be maintained on the side of the protrusion 331c of the torsion spring 331, and the second spacer 333 can be maintained on the side opposite to the protrusion 331c in the heating step described later. So as to fix by bonding or crimping. FIG. 10 shows an example in which an adhesive is used to bond the first spacer 332 and the second spacer 333, respectively, which are shown as the adhesives 341 and 342. However, as the adhesive, a heat-resistant adhesive which does not melt in the heating step is used. Alternatively, molecular pressure bonding may be used.
FIG. 10 is a cross-sectional view of a plane perpendicular to the longitudinal direction of the protrusion 332 c, which passes near the center of the flat portion 332 b. Also, the thickness of the adhesive layer is shown to be emphasized rather than the actual value so that members used for adhesion between parts can be described.

Next, the bridges 332 d and 333 d unnecessary for the finished product of the mover 330 are removed by dicing or the like.
Thereafter, an adhesive layer 343 made of a material which is melted by heating is applied on the spacer portion 332b of the first spacer 332, and the mirror 301 is disposed thereon. Since the spacer portion 331b has the same height as the protrusion 331c, the mirror 301 can be disposed across the protrusion 331c without causing the protrusion 331c to be an obstacle. In FIG. 10, the spacer 332b appears to be slightly lower than the protrusion 331c by the amount of the adhesive layer 343. However, the adhesive layer 343 is actually thin and there is no substantial difference between the heights of the two.
It is desirable to use a low melting point glass paste as the adhesive layer 343. When heat treatment is required for adhesion, if the shrinkage ratio differs between the glass constituting the mirror 301 and the adhesive, it is possible that the mirror 301 is distorted due to contraction upon cooling and the accuracy of scanning is lowered. This is because paste can avoid this.

In addition, an adhesive layer 344 made of a material which is melted by heating is applied also on the spacer portion 333b of the second spacer 333 and the permanent magnet 321 is disposed thereon (on the lower side in FIG. 10). As in the case of the mover 320, the N pole 321n is disposed on one side across the protrusion 331c, and the S pole 321s is positioned on the other side. Although it is desirable to use a cream solder as the adhesive layer 344 in terms of cost, it is not limited thereto. Further, as the permanent magnet 321, it is desirable to use a samarium cobalt type magnet instead of a neodymium type to withstand the subsequent heating process.
The laminated body in which the arrangement of the mirror 301 and the permanent magnet 321 is finished is almost the same as the mover 330 shown in FIG.

Finally, the laminated layers are subjected to heat treatment to melt the adhesive layers 343 and 344 to complete fixation of the mirror 301 and the permanent magnet 321, and the movable element 330 is completed.
As in the case of the mover 320, the mover 330 can be fixed on the top yoke 314 shown in FIG. 6 and FIG. 8A, etc. and can be used to swing the mirror 301 in response to the energization of the drive coil 316. It can be moved. In this case, of course, the mover holding portion 314 a of the top yoke 314 is configured to match the structure and shape of the mover 330.

The above movable element 330 is suitable for mass production because it can be manufactured only by laminating and bonding substantially planar members having protrusions but by cutting them if necessary.
It is also possible to prepare a plurality of torsion springs 331, first spacers 332 and second spacers 333 as sheet-like members in a state in which a plurality of torsion springs 331, first spacers 332 and second spacers 333 are connected in a plurality and connected in a planar manner.

FIG. 11 shows the stacked and fixed state.
In FIG. 11, the torsion springs 331, the first spacers 332 and the second spacers 333 are arranged in three rows and four columns on one sheet. Note that FIG. 11 shows the bridges 332 d and 333 d in a state of being removed by dicing.
The work of forming adhesive layers 343 and 344 on the laminate in this state and arranging the mirror 301 and permanent magnet 321 corresponding to the individual movers 330 is an electronic component using conventional surface mounting (SMT) technology This can be done very efficiently if you use an automatic part mounting machine for

In addition, when a reflow furnace is used, heat treatment can also be easily performed using a conventionally widely used apparatus.
In FIG. 11, the mirror 301 (and the permanent magnet 321 hidden behind) is fixed only to the uppermost left individual, but similar fixing can be performed simultaneously to all the individual. And after that, the movable element 330 of each individual can be separated. In addition, depending on the use of the mover 330, using the plurality of movers 330 while being connected is not hindered.

If the above configuration is adopted, the mover 330 usable for the actuator 300 can be efficiently manufactured using the conventionally used device in the same process as mounting of the conventionally used electronic component. it can. Therefore, the mover 330 can be manufactured at low cost, which also contributes to the cost reduction of the actuator 300.
When the permanent magnet 321 can be soldered directly to the torsion spring 331, the second spacer 333 can be omitted. In this case, the adhesive layer 344 may be directly formed on the surface of the flat portion 331 b opposite to the protrusion 331 c, and the permanent magnet 321 may be disposed thereon.

  Also in the mover 330, as in the case of the mover 320, the permanent magnet 321 is provided as a first member on the surface of the flat portion 331b on which the projection 331c protrudes, and the mirror 301 is used as a second member. It may be provided on the opposite side. In this case, the explanation has been made above except that the permanent magnet 321 is fixed on the first spacer 332 and the mirror 310 is fixed on the second spacer 333 and the materials of the spacers and the adhesive layer used are changed accordingly. The structure and method of manufacture are equally applicable.

[4. Control of the lighting interval of the beam according to the scanning position in the main scanning direction (FIGS. 12 to 17)
Next, control of the lighting interval of the beam according to the scanning position in the main scanning direction of the outgoing light L2 will be described. Since the scanning position in the main scanning direction corresponds to the direction of the mirror 301 in the actuator 300, the control described here is also control according to the direction of the mirror 301.

First, features of the swinging operation of the mirror 301 by the actuator 300 will be described with reference to FIGS. 12 to 14.
FIG. 12 is a graph showing the relationship between the scanning angle of the mirror 301 and the absolute value of the scanning angular velocity, FIG. 13 is a diagram showing an example of the drive signal of the LD module 21, and FIG. 14 is the emitted light formed on the scanning line It is a figure which shows the example of the spot by L2.

  According to the experiments of the inventors, it is known that the moving speed of the mirror 301 rocked by the actuator 300 is not constant. Since the mirror 301 stops at the end of the rocking path and moves in the other part, it is clear that there is a fluctuation in the moving speed, but the speed is roughly the end of the rocking path as shown in FIG. The slower you go to club, the faster you go to central. When rotating counterclockwise as well as clockwise, only the direction of movement is different, and at the same position, the speeds are approximately equal.

Therefore, in FIG. 12, the position on the rocking path (represented by the rotation angle and referred to as "scanning angle") is taken on the horizontal axis, and the absolute value of the angular velocity at that position is taken on the vertical axis. The change is illustrated.
Since the rotational speed of the mirror 301 fluctuates in this way, when the LD module 21 is driven by the drive signal drv1 having pulses at equal intervals as shown in FIG. A spot 72 of the outgoing light L2 is formed. That is, spots are formed roughly at the central portion in the main scanning direction and finely distributed at the end portions. For this reason, the detection resolution of the object is also coarser at the central portion than at the end.

When the detection of an obstacle is considered as the application of the object detection device 10, this state is not preferable because the importance near the center of the visual field is considered to be the highest.
Therefore, the object detection apparatus 10 is provided with a control circuit for controlling the pulse interval of the drive signal of the LD module 21 in accordance with the scanning angle of the mirror 301.

FIG. 15 shows the configuration of the control circuit.
The control circuit 351 illustrated in FIG. 15 corresponds to a cycle control unit, and roughly performs operations related to drive control of the drive coil 316, detection of the rotation speed of the mirror 301, and control of the lighting interval of the LD module 21.

  First, for drive control of the drive coil 316, the control circuit 351 sets the range and period of the scan to be executed by the actuator 300 for the drive signal generation circuit 352 that generates the drive signal 353 to be applied to the drive coil 316. Do. The drive signal generation circuit 352 generates a drive signal 353 of an appropriate level of a voltage which fluctuates at an appropriate cycle in accordance with the set value, and applies the drive signal 353 to the drive coil 316 of the actuator 300. As a result, as described with reference to FIG. 8A, the mirror 300 can be rocked by the actuator 300.

  Next, for detection of the rotational speed of the mirror 301, the detection circuit 354 detects an induced voltage generated in the sensing coil 317 of the actuator 300, and an ADC (analog digital converter) 355 converts the voltage to a digital value in real time. The value is corrected by the difference calculation unit 357 and supplied to the control circuit 351. The control circuit 351 calculates the rotation speed of the mirror 301 based on the voltage value. The number of turns of the sensing coil 317 may be the same as that of the drive coil 316 and may be reversely wound to that of the drive coil 316, but is not limited thereto.

Here, when the mirror 301 is swung, induced electromotive force is generated in the sensing coil 317 due to two types of factors.
The first factor is induced electromotive force due to fluctuation in the strength and direction of the magnetic field generated by the drive coil 316 due to voltage fluctuation of the drive signal applied to the drive coil 316.
The second factor is the induced electromotive force due to the fluctuation of the magnetic field strength caused by the swinging of the permanent magnet 321. When the permanent magnet 321 swings as described with reference to FIG. 8A, the variation speed of the strength of the magnetic field generated thereby in the sensing coil 317 can be considered to be approximately proportional to the rotational angular velocity of the permanent magnet 321. Since the rotational angular velocity of the permanent magnet 321 is also the rotational angular velocity of the mirror 301, the strength of the induced electromotive force generated due to the second factor can be considered to be proportional to the rotational angular velocity of the mirror 301.

The mutual induction voltage pattern storage unit 356 and the difference calculation unit 357 are provided to subtract the value of the induced electromotive force due to the first factor among the above from the output of the ADC 355.
That is, in the actuator 300, the mutual induction voltage pattern storage unit 356 displays the transition of the voltage value of the induction voltage generated in the sensing coil 317 by mutual induction when the drive signal is applied to the drive coil 316 with the permanent magnet 321 removed. And one cycle of the drive signal is stored in association with the phase of the drive signal. Then, when applying a drive signal to the drive coil 316 in order to swing the mirror 301, the drive signal generation circuit 352 supplies a timing signal indicating the phase of the drive signal to the mutual induction voltage pattern storage unit 356. The mutual induction voltage pattern storage unit 356 supplies a voltage value corresponding to the current timing to the difference calculation unit 357 based on the timing signal.

The difference calculation unit 357 subtracts the voltage value supplied from the mutual induction voltage pattern storage unit 356 as the contribution of mutual induction from the value of the induction voltage actually generated in the sensing coil 317 supplied from the ADC 355. The difference between the results is supplied to the control circuit 351.
As described above, it is possible to supply the value of the induced voltage proportional to the rotational angular velocity of the mirror 301 to the control circuit 351. The change of the induced voltage supplied to the control circuit 351 is plotted on the horizontal axis as the time of a half cycle from one end to the other end of the swing range of the mirror 301, as shown in a graph 361, as shown in FIG. It is considered that the shape is substantially similar to the graph of rotational angular velocity.

The control circuit 351 multiplies the voltage value VR (t) supplied from the difference calculating unit 357 at time t by the proportional constant K which is obtained and set in advance to obtain the angular velocity ω (t) of the mirror 301 as ω (t). ) = K × VR (t).
The value of K can be obtained, for example, by comparing the value obtained by measuring the rotation angle of the mirror 301 for a half cycle by another means with the integral value of the voltage value VR (t) for a half cycle.

Further, the control circuit 351 can obtain the lighting interval T for lighting the LD module 21 so that a desired resolution can be obtained on the scanning line 71 a in the main scanning direction, using ω (t). In terms of resolution, T = π · (ψ / 180) / ω (t).
In order to control the lighting interval of the LD module 21, the control circuit 351 obtains the lighting interval T in real time according to the supply of the voltage value VR (t) from the difference calculating unit 357, and a pulse indicating the value of T The width modulated signal is provided to a pulse generator 358.

  The pulse generator 358 performs pulse width modulation in accordance with the pulse width modulation signal, generates a timing signal having a pulse of interval T, and supplies the timing signal to the laser drive circuit 22. The laser drive circuit 22 generates a drive signal for lighting the LD module 21 at the timing of the pulse included in the timing signal supplied from the pulse generator 358, and supplies the drive signal to the LD module 21.

  The pulse interval supplied to the pulse generator 358 by the control circuit 351 is represented by a graph 362 when the time is plotted on the horizontal axis as in the graph 361 and the period from one end to the other end of the oscillation range of the mirror is shown. . That is, in the control circuit 351, when the mirror 301 is near the center of the swing path and the induced voltage is at a high level (first level) according to the induced voltage generated in the sensing coil 317, As compared with the case where the induced voltage is near the end of the swing path and the induced voltage is at a low level (second level), control is performed to shorten the blinking cycle of the LD module 21.

As a result, the drive signal of the LD module 21 generated by the laser drive circuit 22 has different pulse intervals according to the moving speed of the mirror 301 as drv2 shown in FIG. The beam spot 72 obtained by deflecting the laser beam L1 controlled in this way by the mirror 301 is, as shown in FIG. 17, generally over the entire length of the scanning line 71a in the main scanning direction. It will be arranged at equal intervals. And thereby, the object detection apparatus 10 can perform detection of an object with the substantially equal resolution within the visual field 70.
In the sub-scanning direction, since the mirror 351 is kept stationary while scanning for one line in the main scanning direction, the above problem does not occur, and the adjustment of the lighting interval is unnecessary.

The control circuit 351 described above may be provided as part of the processor 53 or separately from the processor 53. Further, the function of the control circuit 351 may be realized by dedicated hardware, or may be realized by causing a general purpose processor to execute software, or a combination of them.
Further, although the example of performing control based on the voltage value of the induced voltage generated in the sensing coil 317 has been described in the example of FIG. 15, similar control is possible using the current value of the induced current.

[5. Configuration of light receiving unit 40 (FIGS. 18 to 24)]
Next, the configuration of the light receiving unit 40 will be described in detail. The object detection device 10 has one feature in that the aperture 44 is provided on the focal plane of the condenser lens 42 in the light receiving unit 40, and therefore, this point will be mainly described.

First, the nature of the laser beam L1 emitted from the light emitting unit 20 will be described.
FIG. 18 is a view schematically showing an optical path of a laser beam emitted from the light emitting unit 20. As shown in FIG.
The LD module 21 of the light projecting unit 20 is provided with a plurality of light emitting points 21a1 to 21a3 as shown in FIG. The light emitting points 21a1 to 21a3 respectively output laser beams B1 to B3 having a certain extent of spread. Further, these light emitting points 21a1 to 21a3 are arranged at close positions, but are necessarily arranged with a certain extent. Of course, the number is not limited to three.

  On the other hand, the projection optical system 23 is designed to generate a beam of parallel light from the laser light output from the LD module 21. For example, when the light projecting optical system 23 is configured by a convex lens in which any light emitting point (here, the light emitting point 21a2) is positioned at the focal point, the laser light B2 output by the light emitting point is the power of the convex lens Thus, the beam C2 of collimated light traveling along the optical axis of the convex lens can be obtained.

However, although the laser beams B1 and B3 output from the light emitting points 21a1 and 21a3 at positions deviated from the focal point are parallel light due to the power of the convex lens, they are slightly inclined with respect to the optical axis It will be beams C1 and C3 that move in the direction.
Therefore, as a whole, when the laser beams output from the light emitting points 21a1 to 21a3 pass through the light projecting optical system 23, they become approximately parallel beams but laser beams having a slight spread. The spread angle can be regarded as constant at a position sufficiently away from the light projection optical system 23, and the angle is taken as the divergence angle α of the laser beam L1 or the emitted light L2.

Next, the detailed configuration of the aperture 44 provided in the light receiving unit 40 and the effect thereof will be described.
First, in the object detection device 10 of this embodiment, a silicon photomultiplier (SiPM) is used as the light receiving element 43 provided in the light receiving unit 40. The SiPM is an array of avalanche photodiodes (APD) operating in Geiger mode, and can obtain high detection sensitivity that can be detected from one photon, high multiplication factor, high-speed response, excellent time resolution, and the like.

As an example, in a general APD, the output signal has an amplification factor of about 50 times that of the input signal (the intensity of light incident on the light receiving surface), and MPPC ( Multi- pixel Photon Counter) sold by Hamamatsu Photonics Some of the registered trademarks can obtain an amplification rate of about 100,000 times (https://www.hamamatsu.com/resources/pdf/ssd/Photodetector_lidar_kapd0005e. Pdf).

  Therefore, by using SiPM, even weak return light L4 can be detected, so an object detection apparatus capable of detecting a distant object with low light reflectance can be configured using a low-intensity laser beam. it can. Since an amplification factor of about 2000 times that of APD can be obtained with SiPM, theoretically, using SiPM, the laser beam with an output of 1/2000 is equivalent to that of an object detection apparatus using APD. The object detection capability of

  In order to increase the intensity of the laser beam, a large and expensive apparatus is required. Therefore, the point that the intensity of the laser beam may be low is a great advantage in downsizing and cost reduction of the object detection device. However, since the size of the light receiving surface of SiPM is larger than that of APD, simply replacing APD with SiPM has the problem of being susceptible to disturbance light.

This point will be described with reference to FIG. FIG. 19 is a diagram showing an optical path of condensing the return light L4 by the condensing lens 42 when the aperture 44 is not provided.
In the light receiving unit 40, the condenser lens 42 is designed to focus the incident return light L4 on the focal plane. Here, the focal length is f. The return light corresponds to the emitted light having the divergence angle α as described with reference to FIG. 18, and returns to the object detection device 10 from the field range having the spread of the α. However, here, once the return light L4 is regarded as a perfect parallel light.

  Then, the return light L4 incident on the condensing lens 42 along the optical axis is condensed at the focal point of the condensing lens 42 and then diverges. Then, in order to receive the return light L4 over the entire light receiving surface, the light receiving element 43 is preferably disposed at a position ahead of the focal point where the return light L4 spreads to the width D ′ of the light receiving surface. The distance from the condenser lens 42 to the light receiving element 43 at this time is d ′. The light receiving element 43 may be disposed in front of the focal point. In this way, d ′ can be reduced to miniaturize the apparatus, but from the viewpoint of reducing the influence of disturbance light, it should be disposed prior to the focal point Is preferred.

  By the way, not only the return light L4 but also disturbance light from various directions enters the object detection device 10. A part of the light reaches the light receiving unit 40 in the same or close light path as the return light L4. Then, considering the property that light passing through the center of the condenser lens 42 goes straight even if it passes through the condenser lens 42, disturbance light X in the range of the viewing angle The disturbance light entering the condenser lens 42 will enter the light receiving element 43. The value of φ can be approximately obtained by φ = arctan (D ′ / d ′). "Arctan" is an arc tangent.

When APD is used as the light receiving element 43, the effective diameter of the light receiving surface is, for example, about 0.08 mm, so if D '= 50 mm, then φ ≒ 0.1 degrees, and only the disturbance light of a very limited range is received. It does not enter 43. Therefore, the influence of disturbance light X on object detection is limited.
However, when SiPM is used as the light receiving element 43, the effective diameter of the light receiving surface is, for example, about 1.3 mm, and in this case, D ′ = 50 mm, φ ≒ 1.5 degrees, and disturbance light with a fairly wide viewing angle Is incident on the light receiving element 43. The sensitivity of the SiPM may be extremely high. In this situation, when the sunlight is strong, the light receiving element 43 is saturated by the disturbance light X, the return light L4 can not be detected, and distance measurement can not be performed.

Therefore, in the configuration of FIG. 19, there is a problem that it is difficult to use SiPM as the light receiving element of the object detection device.
Therefore, in this embodiment, this problem is solved by providing the aperture 44 on the focal plane of the condenser lens 42.

This point will be described with reference to FIGS. 20 and 21. FIG. 20 is a diagram showing an optical path of condensing of the return light L4 by the condensing lens 42 when the aperture 44 is provided. FIG. 21 is a view showing the arrangement of the light passing area of the aperture 44. As shown in FIG.
The aperture 44 is provided on the focal plane of the condenser lens 42, and has a light passing area (opening) 44a for passing the return light L4, and the other part is a light blocking area 44b.

  Here, since the return light L4 actually returns from the field of view range of the spread angle α, even if the aberration of the condenser lens 42 is not taken into consideration, it is not imaged at one point of the focal point, and approximate. Onto the focal plane as a spot of diameter f · tan α. Therefore, in order to pass all the return light L4, the diameter D of the light passing area 44a also needs to be at least f · tan α. However, considering the assembly error of the parts, the diameter D should be slightly larger than the minimum value.

On the other hand, assuming that the distance from the focusing lens 42 to the aperture 44 is d (equal to the focal length f of the focusing lens 42 in the example of FIG. 20), the disturbance light X passing through the light passing area 44a of the aperture 44 has a field of view. The angle is in the range of β = arctan (D / d). Therefore, even if D is too large, the influence of disturbance light becomes large.
According to the inventors' simulation in consideration of these, if the diameter D of the light transmission region 44a is determined in the range of 1 ≦ β / α ≦ 3, some assembly error can be tolerated while suppressing the influence of disturbance light. Thus, the object detection device 10 with high yield and reliability can be configured.

  By providing the aperture 44 as described above, disturbance light from outside the range of the viewing angle β as shown by a broken line in FIG. 22 is blocked by the aperture 44 so as not to be incident on the light receiving element 43. it can. Compared to the configuration shown in FIG. 19, as shown in FIG. 23, the disturbance light X incident from a range between the viewing angle φ and the viewing angle β with the optical axis of the condensing lens 42 as the center is You can also think that you can block light. On the other hand, since the return light L4 incident from the range of the viewing angle (divergence angle) α passes through the aperture 44 and is incident on the light receiving element 43, it can be detected. Of course, the aperture 44 can block the disturbance light further outside the viewing angle φ.

  And, the arrangement of the apertures 44 has little influence on the cost and the manufacturing difficulty. Therefore, it can be said that the influence of disturbance light can be reduced simply and inexpensively by the aperture 44. And thereby, the characteristic of SiPM can be utilized and the object detection apparatus with a favorable detection sensitivity can be comprised at low cost as mentioned above. However, it is not essential to use SiPM, and the present invention is naturally applicable to reduce the influence of disturbance light on other light receiving elements.

  Although the aperture 44 is provided on the focal plane of the condenser lens 42 in the example of FIG. 20, this is not essential. Since the spot of the return light L4 is the smallest on the focal plane, providing the aperture 44 on the focal plane makes it possible to reduce the diameter of the light passing area 44a and is most effective for preventing disturbance light, but it is somewhat focal plane Even if the light passing area 44a has a size matching the spot of the return light L4 at that position, a certain degree of effect can be obtained. Further, if the deviation from the focal plane hardly affects the diameter of the light passing area 44a, it can be regarded as being identical to the case of providing on the focal plane.

  Although not shown in FIG. 20, in the light receiving section 40, a through hole 41a for passing the emitted laser beam L1 is opened in the mirror 41 for guiding the return light L4 to the condensing lens 42. Therefore, since the return light L4 is not reflected at the portion of the through hole 41a, the spot of the return light L4 incident on the light receiving element 43 becomes a dark spot in the region corresponding to the through hole 41a. As a result, it becomes difficult to obtain a peak detection signal in a dark portion, and the substantial detection sensitivity of the light receiving element 43 is accordingly reduced.

  Therefore, as shown in FIG. 24, it is preferable to provide a light diffusion member 46 between the aperture 44 and the light receiving element 43, and diffuse the return light L4 so as to be incident on the light receiving element 43. In this way, the return light L4 can be made to enter substantially uniformly over the entire light receiving surface of the light receiving element 43, and a decrease in detection sensitivity can be prevented. It is conceivable to use ground glass or a holographic diffuser as the light diffusion member 46.

[6. Other Modifications]
This is the end of the description of the embodiment, but in the present invention, the specific configuration of the object detection device, the specific operation procedure, the size of each part, the value of other parameters, the specific shape of parts, etc. It does not restrict to what was demonstrated by the form.
For example, the condensing lens 42 and the light projecting optical system 23 in the embodiment described above can be configured not only by a single lens but also by combining the powers of a plurality of lenses.

Also, the features described in the above items can be applied independently to the device or system. In particular, the light receiving unit 40, the actuator 300, the movers 320, 330, and the like can be distributed as parts alone. Moreover, the application is not limited to the object detection device.
Further, the above-described object detection device 10 can be configured to have a size sufficient to be placed on the palm of a person, and is suitable for being mounted on a car and used as an obstacle detection device for automatic driving. The purpose of use is not limited to this. It can also be fixed to a column or wall and used for fixed-point observation.

  In addition, according to the embodiment of the program of the present invention, one computer or a plurality of computers cooperate with one another to control required hardware, and light emission of the LD module 21 in the object detection device 10 in the embodiment described above. It is a program for realizing a function including a timing adjustment function or executing the processing described in the above-described embodiment.

  Such a program may be stored in the ROM or other non-volatile storage medium (flash memory, EEPROM, etc.) provided in the computer from the beginning. It can also be provided by being recorded on any non-volatile recording medium such as a memory card, CD, DVD, Blu-ray disc and the like. Furthermore, it is possible to download it from an external device connected to the network, install it on a computer, and execute it.

  Further, the configurations of the embodiments and the modifications described above can be implemented in any combination as long as they do not contradict each other, and it is a matter of course that only a part can be extracted and implemented.

DESCRIPTION OF SYMBOLS 10 ... Object detection apparatus, 20 ... Projection part, 21 ... LD module, 22 ... Laser drive circuit, 23 ... Projection optical system, 30 ... Scanning part, 31 ... Mirror, 32 ... Actuator, 40 ... Light reception part, 41, DESCRIPTION OF SYMBOLS 48 Mirror, 42 Focusing lens 43 Light receiving element 44 Aperture 46 Light diffusion member 51 Front end circuit 52 TDC 53 Processor 54 Input / output unit 61 Top cover 62: rear cover, 63: cover clip, 64: protective material, 70: field of view, 71: scanning line, 72: spot, 300, 380: actuator, 301, 381: mirror, 304, 384: rotation axis, 311: core yoke, 312 ... frame yoke, 313 ... coil assembly, 314 ... top yoke, 315 ... screw, 316 ... drive coil, 317 ... sensing car 302, 330: permanent magnet, 321s: S pole, 321n: N pole, 322, 331: torsion spring, 323: connection holder, 332: first spacer, 333: second spacer, 341 to 344 ... adhesive layer, 351 ... control circuit, 352 ... drive signal generation circuit, 353 ... drive signal, 354 ... detection circuit, 355 ... ADC, 356 ... mutual induction voltage pattern storage unit, 357 ... difference calculation unit, 358 ... pulse generator , 382 ... axis, 383 ... holder, L1 ... laser beam, L2 ... emission light, L3, L4 ... return light

Claims (7)

A laser light source in which a plurality of light emitting points are arranged;
A lens for generating a laser beam having a divergence angle in the arrangement direction of the plurality of light emitting points from the laser light output from the plurality of light emitting points;
A light receiving element which is one silicon photomultiplier (SiPM) corresponding to the laser beam ;
An optical system that projects the laser beam to the outside and guides incident light that is incident from the outside along the same optical axis as the projection and guides it to the light receiving element;
A scanning unit that periodically changes a projection direction of the laser beam by the projection unit;
Object detection for detecting the distance to an object on the optical path of the laser beam and the direction of the object based on the light projection timing and light emission direction of the laser beam and the timing of the light detection signal output by the light receiving element An object detection apparatus comprising:
The optical system is
An optical element for separating the incident light from the light projection path of the laser beam;
A condenser lens for focusing incident light separated by the optical element on a predetermined focal plane;
And an aperture disposed on a focal plane of the condenser lens,
The size of the divergence angle is α, the diameter of the light passing region of the aperture in the direction corresponding to the divergence angle is D, and the distance from the focusing lens to the aperture is d, β = arctan (D / d) An object detection apparatus characterized in that α ≦ β. The object detection apparatus according to claim 1, wherein
An object detection apparatus characterized in that 1 ≦ β / α ≦ 3. The object detection device according to claim 1 or 2, wherein
An object detection apparatus characterized in that the light having passed through the condenser lens is incident on the entire light receiving surface of the silicon photomultiplier. The object detection device according to any one of claims 1 to 3, wherein
An object detection apparatus comprising a light diffusion member between the aperture and the light receiving element. A laser beam output from a laser light source in which a plurality of light emitting points are arranged is allowed to pass through a lens to generate a laser beam having a divergence angle in the arrangement direction of the plurality of light emitting points;
The laser beam is projected to the outside while periodically changing its projection direction by the scanning unit, and light incident from the outside is guided along the same optical axis as the projection.
The optical element separates the incident light from the projection light path of the laser beam, and the separated incident light is imaged on a predetermined focal plane by a condenser lens.
An aperture disposed on the focal plane of the condenser lens, wherein the size of the divergence angle is α, the diameter of the light passing region of the aperture in the direction corresponding to the divergence angle is D, and the condenser lens Assuming that the distance to the aperture is d, β = arctan (D / d), the aperture focused by the focusing lens is narrowed by the aperture where α ≦ β,
The light having passed through the aperture is made incident on a light receiving element which is one silicon photomultiplier (SiPM) corresponding to the laser beam ,
Detecting the distance to the object on the optical path of the laser beam and the direction of the object based on the light projection timing and light emission direction of the laser beam and the timing of the light detection signal output from the light receiving element Object detection method to be characterized. Corresponding a laser light source in which a plurality of light-emitting points are arranged, the plurality of laser beams emission point is output, and a lens to produce a laser beam having a divergence angle in the direction of arrangement of said plurality of light emitting points, and the laser beam A light receiving element which is one silicon photomultiplier (SiPM), and the laser beam is projected to the outside, and incident light from the outside is guided along the same optical axis as the light projection, and the light receiving element Optical system for guiding the light beam, a scanning unit for periodically changing the light projection direction of the laser beam by the light projection unit, a light emission timing and light projection direction of the laser beam, and a light detection signal output from the light receiving element And an object detection unit for detecting a distance to an object on the optical path of the laser beam and a direction in which the object is located based on the timing, and the optical system includes the laser beam An optical element separated from the light projection optical path, a condenser lens for forming an incident light separated by the optical element on a predetermined focal plane, and an aperture disposed on the focal plane of the condenser lens. A design method for designing an object detection apparatus comprising:
Based on the size α of the divergence angle and the distance d from the focusing lens to the aperture, β = arctan (D / d), in the direction corresponding to the divergence angle of the light passing area of the aperture A diameter D is determined so as to satisfy α ≦ β. A method of designing an object detection apparatus according to claim 6, wherein
A method of designing an object detection apparatus characterized in that the diameter D is set so as to satisfy 1 ≦ β / α ≦ 3.

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