TW202101188A - High resolution touch sensor apparatus and method - Google Patents

Abstract

A sensor array (10) comprising a plurality of touch sensitive pixels, each pixel (12) comprising a capacitive sensing electrode (14) and a reference capacitor (16) connected in series with the capacitive sensing electrode (14) to provide an indicator voltage that is indicative of the proximity of a conductive object to be sensed.

Description

High-resolution touch sensing device and method

The present invention relates to devices and methods, in particular to methods of touching sensing surfaces, controlling and obtaining signals from such surfaces, and methods of manufacturing such surfaces.

The security and verification of user identity is an increasingly important part of the overall technology; to give a few examples, it has participated in:

. User equipment (UE) used for communication and user access to media content;

. Computer devices and systems that store and provide access to sensitive information;

. Devices and systems used in financial transactions and building access control; and

. Access control for vehicles.

Now, the user’s biometric measurement is common in all these and other environments; biometric measurements, such as iris scanning and face recognition, rely on lighting and the camera’s field of view; by presenting users’ videos or photos It is also possible for the camera to circumvent such security measures.

Multiple fingerprint sensors have been considered safer, but it is possible to overcome the security they provide. The manufacturing requirements of such sensors make them integrated with other electronic devices, such as mobile phones and other UEs. Difficult; especially, fingerprint sensing requires very high resolution-at least hundreds of pixels per inch.

An example of such a sensor is Apple’s Touch ID (RTM); this sensor is based on laser-cut sapphire crystal, which uses a detection ring to surround the sensor to detect the presence of the user’s finger; The touch ID (RTM) sensor uses capacitive touch sensing to detect fingerprints and has a resolution of 500 pixels per inch (PPI).

Capacitive sensors, such as those that use the capacitive effect associated with the surface profile of the fingerprint. Each sensor array pixel includes an electrode that serves as one plate of a capacitor and a leather that serves as the other plate. The dermal layer, which is conductive, and the non-conductive epidermal layer that acts as a dielectric. The closer the dermis is to the pixel electrode, the greater the capacitance, so the surface contour of the skin can be measured by measuring the capacitance of each pixel (for example, based on the charge accumulated on the pixel electrode) and compiling the data from these pixels. The image is sensed.

Both passive matrix and active matrix capacitive touch sensors have been proposed. Most so-called passive capacitive touch sensing systems use an external drive circuit (such as an integrated circuit, IC) to drive the matrix of passive electrodes, and use a separate readout circuit (such as an IC) to drive the The charge stored on these electrodes is read out during the period; the stored charge changes depending on the small capacitance change caused by the touch event; the passive electrode system is sensitive to environmental noise and interference.

The active matrix capacitive touch sensor includes a switch element in each pixel; the switch element can control the capacitive sensing electrode between the pixel and an analog to digital converter (ADC) connected to a readout circuit. ) Is a conduction path between an input channel; generally, each row of pixels in an active array is connected to one such input channel; therefore, the charge stored in the array can be obtained from the active matrix by The switching elements are controlled to connect each column of the pixels to be read out to the ADC one to one.

Each pixel needs to be connected to the readout circuit, and all pixels in each row are actually connected in parallel; the parasitic capacitances associated with each pixel are thus additionally combined; this sets an inherent restriction that any row can be combined in The number of pixels together; this in turn limits the size and/or resolution of the capacitive touch sensor.

Therefore, for large-area high-resolution touch sensors, there are still notable unmet commercial needs.

The aspects and examples of the present invention are proposed in the claim and the goal is to try to solve at least part of the above technical problems and other problems.

In one aspect, a sensor array is provided, including a plurality of touch sensing pixels, each pixel includes: a capacitive sensing electrode to accumulate a charge in response to sensing the proximity of a conductive object; a reference capacitor, and the capacitor The type sensing electrodes are connected in series, so that in response to a control voltage, an indicator voltage is provided at the connection point (18) between the reference capacitor and the capacitive sensing electrode to indicate the proximity of the conductive object. This arrangement can reduce or overcome the problems related to parasitic capacitance existing in the touch sensor of the prior art.

Each pixel may include a sensing VCI (Voltage Controlled Impedance) with a control terminal connected so that the impedance of the sensing VCI is controlled by the indicator voltage. Generally, the sensing VCI includes at least one TFT (thin film transistor), and the conduction path of the VCI includes a channel of the TFT. The conductive path of the sensing VCI can be connected to a first plate of the reference capacitor (16), and the control terminal of the first VCI is connected to the second plate of the reference capacitor. At least one plate of the reference capacitor can be provided by a metallisation layer of a thin film structure that provides the sensing VCI.

The conductive path of the sensing VCI can be connected to the first plate of the reference capacitor, and in this way, the control voltage is also connected to an input of a readout circuit; this can enable the control voltage to be provided by the pixel The basic circuit of the output signal; this can further solve the problems related to the parasitic capacitance and the signal-to-noise ratio of the prior art touch sensor. Another way to solve the same problem is to connect the conductive path of the sensing VCI to a reference signal supplier to an input of a readout circuit; the reference signal supplier may include a constant voltage current source; therefore, adjust a pixel The impedance of the sensing VCI controls the current from the pixel to the input of the readout circuit.

A selection VCI can also be included in each pixel; this can be connected so that its conduction path is connected in series between the conduction path of the sensing VCI and the reference signal supplier; therefore, switching the selection VCI into a The non-conduction state can isolate the sensing VCI from the reference signal input, but switching the selected VCI into a conduction state allows current to flow through the pixel (depending on the impedance of the sensing VCI). A control terminal of the selection VCI can be connected to receive the control voltage, for example, from a gate drive circuit.

Each pixel may include a reset circuit to set the control terminal (22) of the sensing VCI to a selected reset voltage; the reset circuit may include a reset VCI; a conductive path connecting the reset VCI Between a second plate of the reference capacitor and (a) a reset voltage; and (b) one of a first plate of the reference capacitor. A control terminal (32) of the reset VCI can be connected to another pixel of the sensor to receive a reset signal (for example, from the selection VCI of a pixel in another column of the array connected to a control terminal A channel of the gate drive circuit); the reset signal can be configured to switch the reset VCI into a conducting state, thereby connecting the second plate of the reference capacitor to (a) the reset voltage and (b) One of the first plates of the capacitor. Connect the second plate of the reference capacitor to (a) one of the reset voltages.

Each pixel may include a gate line VCI, and a conductive path of the gate line VCI may connect the reference signal supplier to the first plate of the reference capacitor to provide the control voltage.

One aspect also provides a method of operating a sensor array, the sensor array including a plurality of touch sensing pixels, the method including: applying a control voltage to a reference capacitor of a pixel of the sensor to charge the reference capacitor, and A capacitive sensing electrode, in which the control voltage is responded to, and the reference capacitor and the capacitive sensing electrode together provide an indication voltage to indicate that the pixel senses the proximity of a conductive object.

The indication voltage can be used to control the impedance of a conductive path of an inductive VCI connected to an input channel of a readout circuit; the control voltage can be provided by an output channel of a gate drive circuit, and the The output channel of the gate drive circuit can be connected to the input channel of the readout circuit via the conduction path of the inductive VCI. The method may include operating the inductive VCI to adjust the impedance of a conduction path between the output channel of the gate drive circuit and the input channel of the read circuit; this can help solve problems associated with parasitic capacitance , Where the parasitic capacitance comes from other pixels in the same row, and comes from the swamping signal of the active pixel. When a reference signal supplier is connected to the input channel of the readout circuit through the conductive path of the sensing VCI, another way to solve the same technical problem is provided. In those embodiments, the method may include operating the inductive VCI to adjust the impedance of a conductive path between the reference signal supplier and the input channel of the readout circuit.

The method may include operating a gate line VCI to provide the control voltage by connecting the reference signal supplier to the reference capacitor through a conductive path of the gate line VCI.

The method may include resetting the reference capacitor before a subsequent application of the control voltage; resetting the reference capacitor may include operating a reset circuit using a control voltage, wherein the control voltage is also applied to another of the sensor array A pixel-for example a control voltage used to activate another column of the pixels of the array.

Resetting the reference capacitor may include operating a reset VCI to connect a first plate of the reference capacitor to: (a) a reset voltage; and (b) one of a second plate of the reference capacitor . Resetting the reference capacitor may include connecting the first and second plates of the reference capacitor to each other.

One aspect also provides another pixel, including: a capacitive sensing electrode to accumulate a charge in response to sensing the proximity of a conductive object; a reference capacitor connected in series with the capacitive sensing electrode to respond to a control voltage, The connection point (18) between the reference capacitor and the capacitive sensing electrode provides an indicator voltage to indicate the proximity of the conductive object. Specific embodiments may provide a group of such pixels, for example, may provide a component part of such an array.

In order to avoid any doubt, the disclosure of this application should be viewed as a whole; any feature of any example disclosed herein can be combined with any selected feature of any other example described herein.

For example, the features of the method can be implemented by appropriately configured hardware, and the function of the specific hardware described herein can be used in a method that uses other hardware to implement the same function.

FIG. 1 shows a sensing device 1 including the sensor array 10 of the present disclosure; FIG. 2 illustrates a circuit diagram of such a sensor array 10. The following description should refer to FIGS. 1 and 2 together; from the inspection of FIGS. 1 and 2, it can be seen that the inset A of FIG. 1 shows a detailed view of a pixel of the array 10.

The sensor array 10 includes a plurality of touch-sensitive pixels 12; in general, each pixel 12 is the same as other pixels 12 in the array 10 except for its position in the array. As shown in the figure, each pixel 12 includes a capacitive sensing electrode 14 to accumulate a charge in response to the proximity of the surface of a conductive object; a reference capacitor 16 is connected to the capacitive sensing electrode 14 and connected to a Between a connection point of a gate drive channel 24-1 of the gate drive circuit 24; therefore, a first plate of the reference capacitor 16 is connected to the gate drive channel 24-1, and the reference capacitor 16 A second electrode plate of is connected to the capacitive sensing electrode 14.

Each pixel 12 may also include a sensing VCI (Voltage Controlled Impedance) 20. The sensing VCI 20 has a conduction path and a control terminal (22; inset A of FIG. 1) to control the impedance of the conduction path; the sensing VCI The conductive path 20 can connect the gate drive channel 24-1 to an output of the pixel 12; the control terminal 22 of the VCI is connected to the capacitive sensing electrode 14 and the second plate of the reference capacitor 16 Therefore, in response to a control voltage applied by the gate drive channel 24-1, the reference capacitor 16 and the capacitive sensing electrode 14 act as a capacitive potential divider (capacitive potential divider).

The capacitance of the capacitive sensing electrode 14 depends on the proximity of a conductive surface of an object sensed to the capacitive sensing electrode 14; therefore, when a control voltage is applied to the first reference capacitor 16 In the case of a polar plate, the relative partial voltage between the sensing electrode 14 and the reference capacitor 16 provides an indication of the proximity of the surface of the conductive object of the capacitive sensing electrode 14. This part of the control voltage provides an indicator voltage, which is located at the connection point 18 between the reference capacitor 16 and the capacitive sensing electrode 14; the indicator voltage can be applied to the sensing VCI 20 The control terminal 22 provides an output from the pixel 12 indicating the proximity of the conductive object.

Plural pixels can be placed sufficiently close together to be able to determine the contours of the skin, such as those related to epidermal ridges, such as those that appear on a fingerprint, palmprint, or other recognized surface of the body; the context of this disclosure will be understood as skin The outline of can include a plurality of ridges and a plurality of recesses between those ridges. During the touch sensing period, the ridges can be relatively closer to a sensing electrode than the "concavities" between those ridges; therefore, the capacitance of a sensing electrode adjacent to a ridge will be higher than The capacitance of a sensing electrode adjacent to a recess. The following description explains how such a system can be provided: a sensor with a sufficiently high resolution is provided in a larger area than previously possible to perform fingerprint and other biometric touch sensing.

As shown in FIGS. 1 and 2, in addition to the sensor array 10, such an inductor may also include a dielectric shield 8, a gate drive circuit 24, and a readout circuit 26; it may also include connections A connector 25 to a host device, which can be provided by a multi-channel connector with a plurality of wires, can be flexible, and can include, for example, a flexible or bendable PCB, a ribbon cable Cable or similar connector; the connector 25 can carry a host interface 27, such as a plug or socket, to connect the wires in the connector to a plurality of signal channels of a host device, wherein the host device includes The induction device1.

The host interface 27 is connected to the readout circuit 26 by the connector 25. A controller (6; FIG. 2) can be connected to the gate drive circuit 24 to operate the sensor array, and connected to the readout circuit 26 to obtain a signal representing the self-capacitance of the pixels of the sensor array 10.

The dielectric shield 8 is usually in the form of a sheet of insulating material, the insulating material may be transparent and flexible, such as a polymer or glass; the dielectric shield 8 may be flexible and bendable; An “active area” of this shielding covers the sensor array 10. In some specific embodiments, the VCI and other pixel elements are arranged on a separate substrate, and the shield 8 covers the elements on the substrate; in other specific embodiments, the shield 8 is These components provide the substrate.

The sensor array 10 can take any of the diversified forms discussed here; different pixel designs can be used, however, usually the pixels 12 include at least one capacitive sensing electrode 14, a reference capacitor 16, and at least one sensing VCI 20.

The array illustrated in FIG. 2 includes a plurality of columns of pixels, such as that illustrated in FIG. 1. 2 also shows the gate drive circuit 24, the readout circuit 26, and a controller 6. The controller 6 is configured to provide a clock signal, such as a periodic trigger, to the gate drive circuit 24 and the readout出circuit 26.

The gate drive circuit 24 includes a plurality of gate drive channels 24-1, 24-2, 24-3 that are operable to individually (that is, independently) control, each such gate drive channel 24-1 , 24-2, 24-3 include a voltage source configured to provide a control voltage output, and each channel 24-1 is connected to a corresponding column of pixels 12 of the sensor array 10. In the configuration shown in FIG. 2, each gate drive channel 24-1, 24-2, 24-3 is connected to the first reference capacitor 16 of each pixel 12 of the sensor array 10 Pole plate. During each clock cycle, the gate driving circuit 24 is configured to activate the gate driving channels 24-1, 24-2, and 24-3 by applying a gate driving pulse to the pixels. One of them; therefore, after a series of cycles, the channels (and therefore the columns) are activated in turn and move from one step in the sequence to the next in response to the clock cycle from the controller 6 .

The readout circuit 26 includes a plurality of input channels 26-1, 26-2, 26-3; each input channel 26-1, 26-2, 26-3 is connected to a corresponding row of the sensor array 10 In order to provide these connections, the conductive path of the sensing VCI 20 in each pixel 12 is connected to the input channel 26-1 of the row.

Each input channel 26-1, 26-2, 26-3 of the readout circuit 26 may include an analog front end (AFE) and an analog-to-digital converter (ADC) to connect to the input channel 26-1 The row obtains a digital signal; for example, it can integrate the current applied to the input channel during the gate pulse to provide the degree of current flowing through the sensing VCI 20 of the active pixel 12 in the row . The readout circuit 26 can use the ADC to convert the signal into digital data; in addition, the analog front end performs impedance matching, signal filtering, and other signal conditioning, and can also provide a virtual reference.

In the sensor array 10 shown in FIG. 2, the conductive channel of the sensing VCI 20 in each pixel connects the input channel of the readout circuit of the row to the gate drive channel of the pixel column; In Figure 2, the gate drive channel in the column therefore provides a reference input. The operation of the sensing VCI 20 adjusts the reference input to provide the pixel output; the output signal from a pixel indicates the charge stored on the capacitive sensing electrode 14 in response to the charge stored on the reference capacitor The reference input.

Fig. 1 contains a grid as a very general illustration of the columns and rows of the pixels 12 that make up the array; this will usually be a straight grid, and usually the columns and rows Will be evenly spaced; for example, the pixels may be square; of course, it should be understood that the grid shown in FIG. 1 is not drawn to scale. Generally, the sensor array has a pixel pitch of at least 200 dots per inch (dpi) (78 dots per centimeter); the pixel pitch can be at least 300 dpi (118 dots per centimeter), for example, at least 500 dpi ( 196 points per centimeter).

The operation of the sensor array 10 of FIG. 2 will now be described.

In each cycle of operation, each of the gate drive circuit 24 and the readout circuit 26 receives a clock signal from the controller 6.

In response to the clock signal, the gate drive circuit operates one of the gate drive channels to apply a control voltage to one of the columns of the array; in each pixel of the column, from the The control voltage of the gate drive channel is applied to the reference capacitor 16 and the capacitive sensing electrode 14 connected in series; the voltage at the connection point 18 between the reference capacitor 16 and the capacitive sensing electrode 14 provides an indication Voltage to indicate the proximity of the capacitive sensing electrode 14 to a conductive surface of an object. The indicating voltage can be applied to the control terminal of the sensing VCI 20 to control the impedance of the conduction path of the sensing VCI 20; therefore, a current is provided from the gate drive through the conduction path of the sensing VCI 20 to the The input channel of the row of pixels; the current is determined by the gate drive voltage and the impedance of the conduction channel.

In response to the same clock signal, the readout circuit 26 senses the pixel output signal in each input channel; this can be received by each input of the readout circuit 26 integrated in the time period of the gate pulse The signal in each input channel, such as the voltage obtained by integrating the current from the corresponding row of the array, can be digitized (for example, using an ADC). Therefore, for each gate pulse, the readout circuit 26 obtains a set of digital signals, and each signal corresponds to a row of the active column during the gate pulse; therefore, the set of signals together represent The active column is a whole, and together represent the output from each pixel indicating the stored charge, and/or together represent the self-capacitance of the capacitive sensing electrode 14 of the pixel.

According to the same process, each of the gate drive channels is activated in turn; this drives the sensing VCI 20 of each pixel connected to the channel into a conductive state for a selected time (usually a gate This period of the pulse wave). By sequentially activating the columns of the array, the readout circuit can scan the sensor array in a row operation. Other pixel designs, other scanning sequences, and other types of sensor arrays can be used.

Figure 3 illustrates another sensor array that can be used in the device illustrated in Figure 1.

Figure 3 shows a sensor array 10, including a plurality of pixels and a reference signal supplier 28, the reference signal supplier 28 is used to supply a reference signal to the pixels; this can avoid the need for the gate drive power supply It is also necessary to provide the read signal current demand.

FIG. 3 also shows the gate drive circuit 24, the readout circuit 26, and the controller 6.

The sensor array 10 can also benefit from the inclusion of a reset circuit 32, 34 in each pixel; this allows the control terminal 22 of the pixel to be inactive when the pixel is inactive (for example, when another column of the array The gate pulse that is being applied to a different column of the array is pre-charged to a selected reset voltage.

In these embodiments, the sensor may also include a reset voltage supply 42 to supply a reset voltage to each of the pixels 12 of the array as described below; the reset voltage supply 42 may include The voltage source circuit can be configured to supply a controllable voltage, and can be connected to the controller 6 to enable the controller 6 to adjust and fix the reset voltage.

The reset voltage can be selected to adjust the sensitivity of the pixel; in particular, usually the output current of the sensing VCI 20 has a characteristic that depends on the indicator voltage at the control terminal 22 and its turn-on voltage; therefore, based on the sensing VCI The turn-on voltage of 20, the reset voltage can be selected; the characteristic can also include a linear region, and the inductive VCI 20 operates better in the linear region.

The pixels illustrated in FIG. 3 are similar to the pixels illustrated in FIGS. 1 and 2. Each pixel includes a capacitive sensing electrode 14 and a reference capacitor 16 connected to a capacitive sensing electrode 14; The connection between these two capacitors provides an indicator voltage, which can be, for example, the control terminal 22 connected to a sensing VCI 20. In addition, the pixels of the sensor array illustrated in FIG. 3 further include two VCIs 34, 38, and a connection to the reset voltage supply 42 and a connection to the reference signal supply 28 .

As mentioned above, the sensing VCI 20 is arranged substantially as described above with respect to FIG. 1, and the control terminal 22 of the sensing VCI 20 is connected to the connection between the reference capacitor 16 and the capacitive sensing electrode 14. Point; However, in Figure 3, the conduction path of the induction VCI 20 is connected differently from Figure 1; in particular, the conduction channel of the selected VCI 38 connects the conduction channel of the induction VCI 20 to the reference signal supplier 28. The reference signal supplier 28 provides a voltage _Vref ; therefore, the conduction channel of the inductive VCI 20 is connected in series between the conduction channel of the selection VCI 38 and the input of the readout circuit of the row . Therefore, the selected VCI 38 plays a role of a switch. When it is turned on, the sensing VCI 20 is connected between the _Vref /reference signal supplier 28 and the input of the readout circuit, and when it is not turned on, The reference signal supplier 28 disconnects the inductive VCI. For the sake of clarity, the connection between the conduction channel of the selected VCI and V _ref and the reference signal supplier 28 is only shown in the uppermost column of the array of the pixels; this is used in the figure Mark V _ref to indicate the connection between the lower columns of the array and the reference signal supplier 28.

Therefore, the selection VCI 38 is operable to prohibit the supply of signals from any inactive pixels to the input of the readout circuit 26; this can help confirm that only those pixels that are active (for example, those The signals of the pixels in the column to which the gate drive pulse is being applied).

In a specific embodiment, each row of the pixels is actually connected to a ground or reference voltage; because of this, there is no voltage difference on each of the rows, so parasitic capacitance is minimized. In addition, a current-driven reference signal supplier can be used instead of a voltage-driven one, so as to be able to further reduce the activity on the inputs of the readout circuit 26. Any influence of parasitic capacitance.

The gate drive channel of the pixel column is connected to the first plate of the reference capacitor 16 and to the control terminal of a selection VCI 38; as in the pixel illustrated in FIGS. 1 and 2, the reference The connection point of the capacitor 16 and the capacitive sensing electrode 14 means that the gate driving voltage is divided between the reference capacitor 16 and the capacitive sensing electrode 14 to provide the indicator voltage to control the sensing VCI 20. However, the connection point to the control terminal 40 of the selection VCI 38 means that the conductive path of the sensing VCI 20 is cut off from the reference signal supplier 28 when the pixel is not active.

A control terminal 22 of the sensing VCI 20 is connected to the second plate of the reference capacitor 16; the conductive path of the sensing VCI 20 connects the reference signal supplier 28 to the readout circuit 26 of the pixel row The input.

A conductive path of the reset VCI 34 is connected between the second plate of the reference capacitor 16 and a voltage output of the reset voltage supply to receive the reset voltage; the reset VCI 34 The control terminal 32 is connected to a reset signal supplier, such as the gate drive channel of another column of the sensor array; during the activity period of another column of the array (for example, the gate before the column of the pixel) This can cause the reset VCI 34 to discharge the reference capacitor 16 or cause the control terminal 22 of the sensing VCI 20 to be pre-charged to the reset voltage.

The operation of the sensor array of FIG. 3 will now be described.

Each of the gate drive circuit 24 and the readout circuit 26 receives a clock signal from the controller 6; in response to this clock signal, the gate drive circuit 24 activates a first gate drive of the gate drive circuit 24 Channel to provide a gate pulse to a column of the array 10; therefore, a control voltage is applied to the selected VCI 38 of the pixels in the first column (the active column during the gate pulse) Control terminal.

The control voltage is also applied to the control terminal of the reset VCI 34 of the pixels in a second column (inactive during the gate pulse).

In the first row (the active row), the conduction channel of the selected VCI 38 is switched to a conduction state by the control voltage (for example, provided by the gate pulse); therefore, the selected VCI 38 The conductive channel of the sensor VCI 20 is connected to the reference signal supplier 28.

The control voltage is also applied to the first plate of the reference capacitor 16; with respect to FIGS. 1 and 2 as described above, the proportional voltage division between the sensing electrode 14 and the reference capacitor 16 is between The connection point between the reference capacitor 16 and the capacitive sensing electrode 14 provides an indicator voltage; the indicator voltage is applied to the control terminal 22 of the sensing VCI 20 to control the impedance of the conduction channel of the sensing VCI 20; Therefore, the sensing VCI 20 connects the reference signal supplier 28 to the input channel of the readout circuit 26 of the row, and reveals an impedance between the two to indicate the electrical power of the capacitive sensing electrode 14 capacity. Please note that the reference signal supply can be provided by a constant voltage current supply.

Therefore, a current is supplied from the reference signal supplier 28 to the input channel of the readout circuit 26 of the pixel row through the conduction path of the sensing VCI 20; this current is determined by the voltage and the reference signal supplier's The impedance of the conductive channel of the inductive VCI is determined.

In response to the same clock signal from the controller 6, the readout circuit 26 senses the pixel output signal in each input channel (for example, by integrating the current provided to each input channel), and digitizes the signal ; The integration time of the readout circuit 26 can be equivalent to the period of the gate pulse.

Therefore, during each clock cycle, the readout circuit 26 obtains a set of digital signals, each signal corresponding to the signals induced from each row of the active column during the gate pulse; The output of each pixel 12 in the column (each channel during the gate pulse) indicates the charge stored on the capacitive sensing electrode of the pixel.

In the second (inactive) column, the control voltage is applied to the control terminal 32 of the reset VCI 34; this causes the reset VCI 34 of the pixels in the inactive column to connect their Refer to the second plate of the capacitor 16 to a reset voltage provided by the reset voltage supply; this will discharge the charge accumulated on the pixels of the inactive column (for example, at least partially move ), or charge them to the reset voltage before they are activated next in a subsequent gate pulse. The reset voltage can be selected to adjust the sensitivity of the pixels.

At the boundaries of the pixel array, an N-1 gate line cannot be obtained. A dummy signal can be used to provide the control signal to the reset VCI; the gate driving circuit 24 can provide the dummy signal; This can be provided by a gate drive channel that is only connected to the reset VCI in a column at the boundary of the array, but is not connected to any sense or select VCI.

As illustrated in FIG. 3, the reset VCI 34 of the pixels can be connected to the gate drive circuit, so that each column is discharged in such a way that by activating the immediately preceding column (which can be one of the array) Adjacent column) of the gate pulse.

FIG. 4 shows a signal timing diagram of a pixel in column N operating the sensor array of FIG. 3.

The signal timing diagram of FIG. 4 includes four separate sub-graphs (100, 102, 104, 106) with complex signal values with reference to a common time axis.

The first sub-diagram 100 shows the control voltage 100a applied to the gate line N-1 in response to the gate pulse N-1 100b; the second sub-diagram 102 shows the control voltage 100a applied to the gate line N-1 in response to the gate pulse N 102b. The control voltage 102a of the gate line N; the third sub-figure 104 shows the indication voltages 104a, 104b of the control terminal 22 of a pixel, in which the pixel senses a conductive object at two different distances from the capacitive sensing electrode 14 The fourth sub-picture 106 at the bottom represents the readout signals 106a, 106b, where the readout signals 106a, 106b are from the third sub-picture 104 applied to the input of the readout circuit 26 The pixel.

The time axis of Fig. 4 has three levels T ₀ , T ₁ and T ₂ , indicating different points in time; the interval between T ₀ and T ₁ indicates the duration of the gate pulse N-1, The interval between T ₁ and T ₂ represents the duration of the gate pulse N.

The operation of the subgraphs of FIG. 4 when the sensor array is in operation will now be discussed.

At T ₀ , a control voltage 100 generated in response to the gate pulse N-1 100b is applied from the gate line N-1 to the control of the reset VCI 34 of the pixels in the row N Terminal; this turns on the reset VCI 34 and therefore through the reset VCI 34 between the control terminals 22 of the sensing VCI 20 and the voltage output of the reset voltage supply to open a Conduction path; therefore, the reset voltage is applied to the control terminal 22 of the sensing VCI 20 of the pixel, for example, the voltage of the control terminal 22 of the sensing VCI 20 may be between T ₀ and T ₁ These sub-pictures 104a and 104b can be seen.

As described above, the reset voltage can be selected to adjust the sensitivity of the pixels in the matrix; in particular, the output current of the induced VCI 20 usually has a characteristic, wherein the characteristic depends on the The indicating voltage of the control terminal 22 and its turn-on voltage; therefore, the reset voltage can be selected based on the turn-on voltage of the sensing VCI 20; the characteristic can also include a linear region and the sensing VCI 20 operates at the The linear region is better.

At T ₁ , after the gate pulse N-1 100b has been completed, a gate pulse N 102b from the gate line N causes the gate drive circuit 24 to apply a control voltage 102a to the rows N The first plates of the reference capacitors 16 and the control terminals 40 of the selection VCI 38 of the pixel.

A result of the application of the control voltage 102 to the control terminals 40 of the selection VCI 38 is a value between the reference signal supplier 28 and the sensing VCI 20 of the pixels of the column N The conduction path is opened.

When a conductive surface is sufficiently close to the capacitive sensing electrode 14 of a pixel in column N, as in the case of FIG. 4, an indicator voltage 104a is generated, wherein the indicator voltage 104a depends on the sensing electrode 14 and the capacitive sensing electrode 14 The proportional voltage division between the reference capacitor 16; the indicator voltage generated by the capacitive sensing electrode and the reference capacitor is applied to the control terminal 22 of the sensing VCI 20, thereby being connected to the reference signal supplier 28 A conductive path between and the readout circuit 26 is opened.

Therefore, for example, those complex signals shown at 106 are applied to the corresponding input of the readout circuit 26, and the magnitude of the signal will depend on the proximity of the conductive surface.

The example shown in FIG. 4 overlaps two kinds of signals (106a and 106b) generated by the capacitive sensing electrode 14 arranged at two different distances from a conductive object to one pixel.

The two different positions of the conductive object result in two different capacitances of the sensing electrode (for example, because the skin of the finger provides a second "plate" of a capacitor, where the first "plate" Are provided by the sensing electrode 14); the indicating voltages (104a and 104b) are applied to the control terminal 22 of the sensing VCI 20 of the pixel; therefore, for the two positions of the conductive surface, the The impedance of the conductive path of the sensing VCI 20 will be different.

The signal applied to the input of the readout circuit 26 depends on the impedance of the sensing VCI 20 and therefore is different for the conductive surface at two different distances from the capacitive sensing electrode 14.

This is exemplified by the voltage signals (104a and 104b) and read signal shapes (106a and 106b) of the control terminals 22, as shown in FIG.

At T ₂ , the gate line pulse N 102b is completed, and the gate driving circuit stops applying a control voltage 102a to the pixels in column N; the control voltage is no longer applied to the pixels of the selected VCI 38 Therefore, the control terminal turns off the selected VCIs of column N.

Therefore, the conductive paths through the selective VCI of the pixels in column N are turned off, and the pixel no longer applies a signal (106a and 106b) to the input of the readout circuit.

It can be seen that after the online gate pulse N 102b is completed, some residual charges on the sensing electrode will remain; it should be understood that in the context of this disclosure, the selection of VCI 38 can be used to prevent such residual charges. Such residual charge operates the sensing VCI 20 and therefore causes false signals from the inactive columns.

Different pixel designs can be used in, for example, the configuration described in relation to FIG. 3.

FIG. 5 illustrates a circuit diagram of the sensing pixel 12 illustrated in the array of FIG. 3. However, for clarity, the pixel 12 is displayed in isolation.

It can be seen that the pixel 12 includes a reference capacitor 16, a capacitive sensing electrode 14, a sensing VCI 20, a selection VCI 38, and a reset VCI 34.

The pixel 12 of FIG. 5 is similar to the touch sensing pixel 12 shown in FIG. 1 and the above description, wherein a connection point between the reference capacitor 16 and the capacitive sensing electrode 14 provides an indication voltage, which can be connected To the control end of the sensing VCI 20.

However, the difference between the pixel 12 in FIG. 5 and the touch sensing pixel 12 in FIG. 1 is that it includes a selection VCI 38 and a reset VCI 34.

The conduction path of the selection VCI 38 is connected between the conduction channel of the sensing VCI 20 and a reference signal supplier; therefore, the sensing VCI 20 is one of the selection VCI 38 and a readout circuit 26 The inputs are connected in series. A gate line input of the pixel is connected to the control terminal 40 of the selection VCI 38.

The conductive path of the reset VCI 34 is connected between the second plate of the reference capacitor 16 and a reset voltage supply. The control terminal of the reset VCI 34 is connected to the input of a reset signal supplier of the pixel. When the pixel is combined into an array, this can be, for example, the AND of another column of the pixels in the array. A connection of the gate line.

FIG. 6 still illustrates a further example of a pixel suitable for use in an array such as that illustrated in FIG. 3; this pixel is the same as the pixel described in FIG. 4, except that it includes a gate line VCI 30 and a second Reset VCI 36.

The control terminal 44 of the gate line VCI 30 is connected to the gate drive channel of the other column of the array; the conduction path of the gate line VCI 30 is connected between the reference signal supplier 28 and the reference Between a first plate of the capacitor 16; therefore, the control of the gate line VCI 30 by the gate drive circuit 24 can connect the series connection of the reference capacitor 16 and the capacitive sensing electrode 14 to the reference signal supply When the gate line VCI 30 is closed and non-conducting, the pixel is disconnected from the reference signal supplier 28.

In addition, the gate line signal does not need to supply the current to charge the array for readout.

Just like the pixel of FIG. 5, the reset circuit of the pixel shown in FIG. 6 includes the reset VCI 34, wherein the reset VCI 34 is connected between the second plate of the reference capacitor 16 and a reset Between the voltage supply 42 and also includes a reset VCI 36, where the reset VCI 36 is connected between the first plate of the reference capacitor 16 and the reset voltage supply; the reset VCI The control terminal 32 of the 34 and the control terminal 46 of the reset VCI 36 are connected to a reset signal supplier, such as the gate drive channel of another column of the sensor array mentioned above.

It should be understood that in the context of the present disclosure, other reset circuits may be used; for example, the conductive path of the reset VCI 34 may connect the first plate of the reference capacitor to its second plate (for example, short-circuit the Refer to capacitor 16).

The operation of the pixel 12 shown in FIG. 6 in the array of FIG. 3 is similar to the operation of the pixel 12 shown in FIG. 5 and above; however, except for operating the control terminal of the selection VCI 38, the control voltage The gate line VCI 30 is also operated to connect the first plate of the reference capacitor 16 to the reference signal supplier 28; the reference signal is used between the reference capacitor 16 and the capacitive sensing electrode 14 The connection point provides an indication voltage, as described above with respect to Figs. 1 and 2; when a control voltage is applied to select VCI 38 to connect the reference signal supplier 28 to the input channel of the readout circuit of the row, The indicating voltage is applied to the control terminal of the sensing VCI 20 to control the impedance of the conduction channel of the sensing VCI 20.

In addition, in response to a reset signal sent from a reset signal provider (such as the gate drive channel of another column of the sensor array mentioned above) to the reset VCI 36 and the reset VCI 34 control terminals, A conductive path between the reference capacitor 16 and the reset voltage supply is opened; this causes the reset voltage to be applied to the two electrodes of the reference capacitor 16, and therefore the voltage across the reference capacitor 16 is zero.

Based on the thickness of the dielectric shield and/or the dielectric constant of the shield, the reset voltage may be selected; for example, the reset voltage may be selected to determine the range of capacitance change, wherein the capacitance changes It is related to sensing the complex characteristics of an object (such as the contour of human skin) to provide a complex change in the complex indication voltage from the capacitive potentiometer 14, 16 to be sufficient in different ways within a measurable degree Operate the inductive VCI; for example, based on a threshold voltage of the inductive VCI and based on the thickness of the dielectric shield and/or the dielectric constant of the shield, the reset voltage can be selected so that the skin The multiple ridges and the multiple recesses of the profile can enable the induced VCI to operate in a linear region of its current-voltage characteristics.

The output current of the conduction path of the inductive VCI 20 preferably depends on the indicating voltage applied to the control terminal 22, and in addition, for a given change in the voltage at the control terminal 22, the inductive VCI The change of the output current of 20 preferably depends on the value of the voltage applied to the control terminal 22.

The reset voltage can be beneficially set so that the voltage of the control terminal 22 of the sensing VCI is within a voltage range where the output current of the VCI and the voltage of the control terminal 22 change linearly; if the selected VCI exists, this is Especially correct. It is also possible to select the reset voltage based on a threshold voltage of the induced VCI, for example, such that in a static state, the induced VCI is at the threshold.

The specific embodiments described here generally include one or more voltage controlled impedances (VCI); each such VCI has a control terminal and a conductive path so that its impedance can be applied to one of its control terminals. Voltage controlled impedance; examples of voltage controlled impedance include multiple transistors, such as multiple thin film transistors (TFTs); it should also be understood that when the inductor is implemented by means of voltage controlled impedance, these thin film transistor systems are responsible A complex number of transconduction gates, where the output current (I _drain-source ) of the TFT can depend on the voltage across the gate and source of the TFT (V _gate-source ) .

The dielectric shield may include a thin plate or a layer of insulating material, such as glass or plastic; the insulating material of the dielectric shield described herein may be selected based on one or more of the following: surface roughness, transparency, Chemical inertia (chemical inertia), mechanical strength and toughness, dielectric constant, thermal behaviour (thermal behaviour) and ease of manufacturing; suitable glass substrates include but are not limited to: soda lime, borasilicate And silicon dioxide (SiO2); suitable polymer substrates include but are not limited to polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate Polyethylene naphthalate (PEN).

It should be understood that in the context of the present disclosure, the sensing device can be designed to match specific complex timings.

The readout of the pixel array performed by the readout circuit can be performed on a frame basis, where each column of the pixels is sequentially read out using a dedicated column time, so that Within one column time, all corresponding pixels in the column are read out.

Such a readout is similar to TFT display technology; however, the current example is related to pixel-reading of the sensor array, rather than pixel-writing of a TFT display.

The collection of all columns and related timing can define the frame time of the sensing device; for example, a column time of 25 microseconds (µsec), with a total of 100 columns, results in a frame time of 2.5 milliseconds (msec) The time is 25µsec x 100msecs.

Other timing and readout sequences may also be suitable; for example, in the case of a multiplexer circuit, many conversions must be performed within a single gate line time.

The specific embodiments disclosed herein describe the provision of a reset voltage transmitted to each of the pixels in the pixel array; the pixels in the pixel array can receive the same reset voltage, wherein the The reset voltage is selected in the aforementioned manner.

It should be understood from the above discussion that the specific embodiments shown in the drawings are merely examples, and include plural features that can be summarized, removed or replaced as described herein and as stated in the claims. ; Regarding these diagrams, in general, it should be understood that the plural block diagrams of the general functions are used to represent the functions of the systems and devices described herein; however, it should be understood that the functions need not be separated in this way, and are Should be taken to imply any specific structure of the hardware, but as described below and requested. The functions of one or more elements shown in these illustrations can be further subdivided and/or distributed throughout the disclosed device; in some specific embodiments, one or more elements shown in these illustrations The functions can be integrated into a single functional unit.

For example, it has been mentioned that a controller is used to provide a clock signal; however, it should be understood that in the context of this disclosure, the controller may be part of the gate drive circuit, and/or the gate described herein A pulse signal can be used to replace the clock signal; for example, the operation of the readout circuit and the gate drive circuit can be synchronized by using the gate pulses; for example, each of the readout circuits The integration period of the input channel can be controlled by the gate pulse.

In some examples, the functions of the controller may be provided by a general-purpose processor, which may be configured to execute a method based on any of those described herein; in some examples, the The controller may contain digital logic, such as field programmable gate arrays, FPGA, application specific integrated circuits, ASIC, a digital signal processor, DSP, or by any other Suitable hardware. In some examples, one or more memory devices can store data and/or program instructions for use to implement the operations described herein. The specific embodiments of the present disclosure provide tangible, non-transitory storage media containing program instructions that can be manipulated to program a processor to execute any one or more methods described and/or requests herein Item and/or provide the data processing device as described and/or the requested item here. The controller may include an analog control circuit, wherein the analog control circuit provides at least a part of the control function. A specific embodiment provides an analog control circuit, wherein the analog control circuit is configured to perform any one or more of the control methods described herein.

The above specific embodiments are to be understood as illustrative examples; further specific embodiments can be envisaged. It should be understood that any feature described with respect to any one specific embodiment can be used alone, or combined with other described features, and can also be used to combine one or more features of any other such specific embodiment , Or any other combination of these specific embodiments. In addition, equivalent equipment and modifications not described above can also be used without departing from the scope of the present invention, which are defined in the appended plural claims.

1: induction device

6: Controller

8: Dielectric shielding

10: Sensor array

12: Touch sensor pixels, sensor pixels, pixels

14: Capacitive sensing electrode, sensing electrode, capacitive potentiometer

16: Reference capacitor, capacitive potentiometer

18: Connection point

20: Induction VCI

22: Control terminal, control terminal voltage

24: Gate drive circuit

24-1: Gate drive channel

24-2: Gate drive channel

24-3: Gate drive channel

25: Connector

26: readout circuit

26-1: Input channel

26-2: Input channel

26-3: Input channel

27: Host Interface

28: Reference signal provider

30: Gate line VCI

32: Reset circuit, control terminal

34: Reset circuit, VCI, reset VCI

36: Second reset VCI, reset VCI

38: VCI, select VCI

40: Control terminal

42: Reset the voltage supply

44: control terminal

46: control end

100: Subgraph, first subgraph, control voltage

100a: control voltage

100b: Gate pulse wave N-1

102: Sub-graph, second sub-graph, control voltage

102a: Control voltage

102b: Gate pulse wave N, gate line pulse wave N

104: Sub-picture, third sub-picture

104a: Indicating voltage

104b: Indicating voltage

106: Sub-picture, fourth sub-picture

106a: Read signal

106b: Read signal

V _ref : voltage

V _reset : reset voltage

Some practical embodiments will now be described, but they are only examples and do not limit the invention. Regarding the drawings, where:

FIG. 1 includes a plan view of a sensing device including a sensor array, and inset A of FIG. 1 shows a circuit diagram of a pixel of the sensor array;

FIG. 2 shows a circuit diagram of a sensor array of a sensing device such as that illustrated in FIG. 1;

Figure 3 shows a circuit diagram of another sensor array of the type shown in Figure 1;

FIG. 4 shows a signal timing diagram of the operation of a pixel of a sensor array in the type shown in FIG. 3;

FIG. 5 shows a circuit diagram of a pixel using a sensor array as illustrated in FIG. 3;

FIG. 6 shows a circuit diagram of another pixel using a sensor array such as that illustrated in FIG. 3.

In the drawings, similar reference numbers are used to indicate similar elements.

1: induction device

8: Dielectric shielding

10: Sensor array

12: Touch-sensitive pixels

14: Capacitive sensing electrode

16: Reference capacitance

18: Connection point

20: Induction VCI

22: Control terminal

24: Gate drive circuit

25: Connector

26: readout circuit

27: Host Interface

Claims (34)

A sensor array (10) includes a plurality of touch sensing pixels, and each pixel (12) includes: A capacitive sensing electrode (14) for accumulating a charge in response to sensing the proximity of a conductive object; A reference capacitor (16) is connected in series with the capacitive sensing electrode (14) so as to respond to a control voltage at the connection point (18) between the reference capacitor (16) and the capacitive sensing electrode (14) ) Provide an indicator voltage to indicate the proximity of the conductive object. The sensor array according to claim 1, wherein each pixel (12) includes an induced voltage control impedance (VCI) (20), and has a control terminal (22) connected to make the impedance of the induced VCI (20) Controlled by the indicated voltage. The sensor array according to claim 2, wherein a conductive path of the sensing VCI (20) is connected to a first plate of the reference capacitor (16), and the control terminal ( 22) The second plate connected to the reference capacitor (16). The sensor according to claim 3, wherein the conductive path of the sensing VCI (20) connects the first plate of the reference capacitor (16) to an input (24) of a readout circuit (26). The sensor array according to claim 2, wherein a conductive path of the sensor VCI (20) connects a reference signal supplier (28) to an input of a readout circuit (26). The sensor according to claim 5, comprising a selection VCI (38) having a conductive path connected in series between the conductive path of the inductive VCI (20) and the reference signal supplier (28). The sensor according to claim 6, wherein a control terminal (40) of the selection VCI (38) is connected to the control voltage. The sensor according to any of the foregoing claims, wherein each pixel includes a reset circuit to set the control terminal (22) of the sensing VCI to a selected reset voltage. The sensor according to claim 8, wherein a control terminal (32) of the reset circuit is connected to another pixel of the sensor to receive a reset signal. The sensor according to claim 8 or 9, wherein the reset circuit includes a reset VCI (34, 36), wherein a conductive path of the reset VCI is connected between a second plate of the reference capacitor and (A) a reset voltage; and (b) between one of the first plates of the reference capacitor. The sensor according to claim 10, wherein the reset VCI (34, 36) includes two conduction paths arranged to connect both the first and second plates of the reference capacitor (16) to a reset Voltage. The sensor described in claim 5 or any of the foregoing claims attached to claim 5, wherein each pixel (12) includes a gate line VCI (30), and a conduction of the gate line VCI (30) The path connects the reference signal supplier (28) to the reference capacitor (16) to provide the control voltage. A method of operating a sensor array, the sensor array including a plurality of touch sensing pixels, the method comprising: A control voltage is applied to a reference capacitor of a pixel of the sensor to charge the reference capacitor and a capacitive sensing electrode, wherein in response to the control voltage, the reference capacitor and the capacitive sensing electrode together provide an indication voltage to indicate the pixel The proximity of a conductive object is sensed. The method of claim 13, including using the indication voltage to control the impedance of a conductive path connected to an input channel of a readout circuit by an induced voltage control impedance. The method according to claim 14, comprising operating the inductive VCI to connect the control voltage to the input channel of the readout circuit through the conductive path of the induced voltage to control impedance. The method according to claim 14, including operating the inductive VCI to connect a reference signal supplier to the input channel of the readout circuit through the conductive path of the induced voltage to control impedance. The method according to claim 16, comprising operating a gate line VCI to provide the control voltage by connecting the reference signal supplier to the reference capacitor through a conduction path of the gate line VCI. The method according to any one of claims 14 to 17, comprising resetting the reference capacitance before a subsequent application of one of the control voltages. The method of claim 18, wherein resetting the reference capacitor includes operating a reset circuit using a control voltage applied to another pixel of the sensor array. The method of claim 19, wherein resetting the reference capacitor includes connecting a first plate of the reference capacitor to: (a) a reset voltage; and (b) a second plate of the reference capacitor one of them. The method according to claim 20, wherein resetting the reference capacitor includes connecting both of the first and second plates of the reference capacitor to a reset voltage. The method according to any one of claims 14 to 21, comprising disconnecting a conductive path of the sensing VCI from the supply voltage before the operation of another pixel of the sensor array. The method according to any one of claims 13-22, wherein the sensor array includes the sensor array according to any one of claims 1-12. The sensor array according to any one of claims 1 to 12, or the method according to claim 13 or 23, wherein the voltage-controlled impedances comprise a plurality of transistors, such as a plurality of thin film transistors (TFTs) . The sensor array according to any one of claims 1 to 12, or the method according to claim 13 or 23, wherein the voltage-controlled impedances are built on a glass or polymer substrate, wherein the substrate The capacitive sensing electrode is separated from the sensing object. An adjustable capacitive touch sensor, including a plurality of touch sensing pixels, each including a capacitive potentiometer and a reset voltage supply, which is set as a precharge potentiometer to adjust the pixels of the sensor The sensitivity. The capacitive touch sensor according to claim 26, wherein each of the plurality of touch sensing pixels includes a sensing VCI, wherein the control terminal of the sensing VCI is connected to the capacitive potentiometer and is configured as Relying on an indicator voltage provided by the capacitive potentiometer to provide an output signal. The capacitive touch sensor according to claim 26 or 27, wherein each of the plurality of touch sensing pixels includes a reset VCI, wherein a conductive path of the reset VC is connected in series between the capacitor Between the type potentiometer and a reset voltage supply to pre-charge the potentiometer. A method for calibrating the capacitive touch sensor as described in claim 26, the method comprising: A reset voltage is applied to the potentiometer of at least one pixel to precharge the potentiometer. The method according to claim 29, comprising selecting the reset voltage based on at least one of the following: A turn-on voltage of the induced VCI; A dielectric of the sensor touches a thickness and/or dielectric constant of the shield; and The sensing VCI is a linear region of operation. The method according to claim 29 or 30, wherein the at least one pixel includes: A capacitive sensing electrode (14) for accumulating a charge in response to sensing the proximity of a conductive object; A reference capacitor (16) is connected in series with the capacitive sensing electrode (14) so as to respond to a control voltage at the connection point (18) between the reference capacitor (16) and the capacitive sensing electrode (14) ) Provide an indicator voltage to indicate the proximity of the conductive object. The method according to claim 31, wherein the at least one pixel includes a reset circuit to set the connection point between the capacitive sensing electrode and the reference capacitor to a selected reset voltage. The method according to any one of claims 29 to 32, wherein the at least one pixel includes the feature of the pixel as described in any one of claims 1 to 12 and/or wherein the method includes such as claims 13 to The method described in any one of 25. The capacitive touch sensor according to any one of claims 26 to 28, wherein the pixels include the features defined in any one of claims 1 to 12.

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