Sensing device and electronic device

Abstract

This sensing device for generating a distance image reduces variations in the ranging accuracy of the distance image. The sensing device is provided with: a predetermined number of pixel circuits; and a voltage control unit. A photoelectric conversion element and a detection circuit are provided to each pixel circuit. A predetermined reverse bias voltage is applied between the anode and the cathode of the photoelectric conversion element. The detection circuit detects the presence or absence of photons based on the potential of either the anode or the cathode. The voltage control unit adjusts the reverse bias voltage to a value corresponding to the breakdown voltage of the photoelectric conversion element of each pixel circuit.

Description

Technical Field

[0001] The present technology relates to a sensing device. Specifically, the present technology relates to a sensing device and an electronic device capable of detecting the presence or absence of photons. Background Art

[0002] Generally, a distance measurement method called the time-of-flight (ToF) method has been used in electronic devices having a distance measurement function. The ToF method is a method of measuring distance by obtaining the round-trip time from when irradiated light is emitted from an electronic device to an object until the irradiated light is reflected and returns to the electronic device. For example, a solid-state imaging element has been proposed that measures distance using the ToF method and controls the anode potential of a single-photon avalanche diode (SPAD) according to the sensitivity of each chip based on processing or temperature changes (see, for example, Patent Document 1). Here, an SPAD is a photodiode that improves sensitivity by amplifying a photocurrent.

[0003] Citation List

[0004] Patent Document

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-75394 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the above-described conventional technology, the sensitivity variation of each chip is corrected by controlling the anode potential. However, in a chip, the sensitivity can vary for each pixel according to processing or temperature. In the above solid-state imaging element, the sensitivity variation for each pixel cannot be corrected. Therefore, there is a concern that the sensitivity variation between pixels may cause brightness and darkness distortion in a distance image, resulting in a large variation in distance measurement accuracy.

[0008] In view of this situation, the present technology has been made, and an object thereof is to provide a sensing device that generates a distance image capable of reducing the variation in distance measurement accuracy in the distance image.

[0009] Solution to the Problem

[0010] The present technology has been made to solve the above problems. According to a first aspect of the present technology, a sensing device includes: a predetermined number of pixel circuits, each pixel circuit including a photoelectric conversion element and a detection circuit, a predetermined reverse bias voltage being applied between an anode and a cathode of the photoelectric conversion element, the detection circuit detecting the presence or absence of photons based on the potential of the anode or the cathode; and a voltage control unit that adjusts the reverse bias voltage to a value corresponding to the breakdown voltage of the photoelectric conversion element for each pixel circuit. This results in the effect of correcting the variation in sensitivity.

[0011] In addition, in the first aspect, the voltage control unit may include a predetermined number of individual bias circuits, and the individual bias circuits are respectively connected to different pixel circuits to respectively supply a predetermined individual bias potential to one of the anode and the cathode. This causes the effect of adjusting the individual bias potential for each pixel.

[0012] In addition, in the first aspect, the voltage control unit may further include a common bias circuit, and the common bias circuit is commonly connected to a predetermined number of pixel circuits to supply a predetermined common bias potential to the other of the anode and the cathode. This causes the effect of supplying the common bias potential to all pixels.

[0013] Alternatively, in the first aspect above, it may also be that the above-mentioned individual bias circuit supplies the above-mentioned individual bias potential to the above-mentioned cathode. This causes the effect of adjusting the anode potential.

[0014] Alternatively, in the first aspect above, it may also be that the above-mentioned individual bias circuit supplies the above-mentioned individual bias potential to the above-mentioned anode. This causes the effect of adjusting the potential of the negative electrode.

[0015] In addition, in the first aspect, the pixel circuit and the individual bias circuit may be arranged in each of a predetermined number of pixels. This causes the effect of adjusting the individual bias potential for each pixel.

[0016] In addition, in the first aspect, a predetermined number of pixel circuits may be dispersedly arranged in a plurality of pixel blocks, and the individual bias circuit may be arranged in each of the plurality of pixel blocks. This causes the effect of adjusting the individual bias potential for each pixel block.

[0017] In addition, in the first aspect, a predetermined number of pixel circuits may be dispersedly arranged in a plurality of lines, and the individual bias circuit may be arranged in each of the plurality of lines. This causes the effect of adjusting the individual bias potential for each line.

[0018] In addition, in the first aspect, the individual bias circuit may be arranged at a position where the thermal distribution in the pixel array unit is not biased. This causes the effect of uniform heat distribution.

[0019] In addition, in the first aspect, the sensing device may further include a voltage dividing resistor network, wherein a predetermined number of nodes are connected to each other via resistors, a predetermined number of nodes may be respectively connected to different individual bias circuits, and each individual bias circuit may supply an individual bias voltage corresponding to a reference voltage that is the voltage of each node connected to it. Thereby, the effect of supplying the bias potential to each pixel through a simple circuit is caused.

[0020] In addition, in the first aspect, the sensing device may further include: a measurement value storage unit that stores measurement values of the breakdown voltages of the photoelectric conversion elements for each pixel circuit; and a setting unit that sets a reference voltage based on the measurement values. Accordingly, an effect of causing a separate bias potential corresponding to the measurement value of the breakdown voltage is achieved.

[0021] In addition, in the first aspect, the voltage control unit may perform control to maintain an error of the breakdown voltage with respect to a target value for each pixel circuit in the detection circuit, and apply a potential corresponding to the error to the anode. This causes an effect of applying a reverse bias corresponding to the error of the breakdown voltage.

[0022] In addition, in the first aspect, the detection circuit may include: a power supply reset switch that disconnects or closes a path between the cathode and the power supply potential; a capacitor inserted between the anode and a low potential lower than a predetermined reference potential; an anode reset switch that disconnects or closes a path between both ends of the capacitor; a cathode reset switch that disconnects or closes a path between the cathode and the reference potential; and a logic gate that generates a pulse signal based on the potential of the cathode. Accordingly, an error of the breakdown voltage is held in the capacitor by controlling the switches.

[0023] In addition, in the first aspect, the voltage control unit may sequentially perform the following operations: a reset control that makes the power supply reset switch enter an off state and makes the anode reset switch and the cathode reset switch enter an on state; a control that holds the power supply reset switch and the anode reset switch in the on state and makes the cathode reset switch enter the off state to hold an error in the capacitor; and a bias control that makes the power supply reset switch enter the on state and makes the anode reset switch and the cathode reset switch enter the off state to supply an excessive bias to the cathode. This results in an effect of supplying an excessive bias after holding the error.

[0024] In addition, according to the second aspect of the present technology, an electronic device includes: a light emitting unit that supplies predetermined irradiation light; a predetermined number of pixel circuits, each pixel circuit including a photoelectric conversion element and a detection circuit, applying a predetermined reverse bias voltage between the anode and the cathode of the photoelectric conversion element, the detection circuit detecting whether or not photons are present in the reflected light with respect to the irradiation light based on the potential of the anode or the cathode; and a voltage control unit that adjusts the reverse bias voltage to a value corresponding to the breakdown voltage of the photoelectric conversion element for each pixel circuit. This causes an effect of correcting a change in sensitivity to light emitted by the light emitting unit.

[0025] In addition, according to the third aspect of the present technology, the sensing device includes: a first pixel circuit including a first photoelectric conversion element; and a first detection circuit that detects the presence or absence of photons based on the potential of the anode or cathode of the first photoelectric conversion element; a second pixel circuit including a second photoelectric conversion element and the first detection circuit, the first detection circuit detecting the presence or absence of photons based on the potential of the anode or cathode of the second photoelectric conversion element; a first bias circuit connected to the anode or cathode of the first photoelectric conversion element; a second bias circuit connected to the anode or cathode of the second photoelectric conversion element; and a reference voltage supply unit that supplies different reference voltages to the first bias circuit and the second bias circuit respectively to supply potentials corresponding to the respective reference voltages. Thereby, an effect of supplying different potentials to each pixel circuit is caused. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a block diagram showing a configuration example of a distance measurement module in the first embodiment of the present technology.

[0027] Figure 2 is a diagram showing an example of a stacked structure of a solid-state imaging element in the first embodiment of the present technology.

[0028] Figure 3 is a block diagram showing a configuration example of a solid-state imaging element in the first embodiment of the present technology.

[0029] Figure 4 is a circuit diagram showing a configuration example between a pixel and a common bias circuit in the first embodiment of the present technology.

[0030] Figure 5 is a diagram showing an example of the arrangement of circuits and elements of each chip in the first embodiment of the present technology.

[0031] Figure 6 is a block diagram showing a configuration example of a signal processing unit in the first embodiment of the present technology.

[0032] Figure 7 is a timing diagram showing an example of fluctuations in the cathode potential and pulse signal in the first embodiment of the present technology.

[0033] Figure 8 is a timing diagram showing an example of fluctuations in the cathode potential in the comparative example.

[0034] Figure 9 is a diagram showing an example of a distance image with sensitivity change in the comparative example.

[0035] Figure 10 is a circuit diagram showing a configuration example of a reference voltage supply unit in the first embodiment of the present technology.

[0036] Figure 11 It is a diagram showing an example of setting a reference voltage in the first embodiment of the present technology.

[0037] Figure 12 It is a timing chart showing an example of cathode potential fluctuation in the first embodiment of the present technology.

[0038] Figure 13 It is a diagram showing an example of the sensitivity of each pixel of a distance image in the first embodiment of the present technology.

[0039] Figure 14 It is a diagram for explaining voltage control in the first embodiment of the present technology.

[0040] Figure 15 It is a flowchart showing an example of measurement processing during shipment in the first embodiment of the present technology.

[0041] Figure 16 It is a flowchart showing an example of distance measurement processing in the first embodiment of the present technology.

[0042] Figure 17 It is a circuit diagram showing an example of pixel configuration in the first modification of the first embodiment of the present technology.

[0043] Figure 18 It is a circuit diagram showing an example of pixel block configuration in the second modification of the first embodiment of the present technology.

[0044] Figure 19 It is a diagram showing an example of the configuration of circuits and elements of each chip in the second modification of the first embodiment of the present technology.

[0045] Figure 20 It is a circuit diagram showing an example of the configuration between a separate bias circuit and a line in the third modification of the first embodiment of the present technology.

[0046] Figure 21 It is a diagram showing an example of the arrangement of circuits and elements of each chip in the third modification of the first embodiment of the present technology.

[0047] Figure 22 It is a diagram showing another example of the arrangement of circuits and elements for each chip in the third modification of the first embodiment of the present technology.

[0048] Figure 23 It is a circuit diagram showing an example of pixel configuration in the fourth modification of the first embodiment of the present technology.

[0049] Figure 24 It is a circuit diagram showing an example of pixel block configuration in the fifth modification of the first embodiment of the present technology.

[0050] Figure 25 It is a block diagram showing an example of the configuration of a solid-state imaging device in the second embodiment of the present technology.

[0051] Figure 26 It is a circuit diagram showing an example of the configuration of a pixel according to the second embodiment of the present technology.

[0052] Figure 27 It is a circuit diagram showing an example of the equivalent circuit of an SPAD in the second embodiment of the present technology.

[0053] Figure 28 It is a graph showing an example of the voltage-current characteristics of an SPAD in the second embodiment of the present technology.

[0054] Figure 29 It is a timing diagram showing an example of the operation of a control circuit in the second embodiment of the present technology.

[0055] Figure 30 It is a circuit diagram showing an example of the state of a pixel circuit when the anode and cathode are reset in the second embodiment of the present technology.

[0056] Figure 31 It is a circuit diagram showing an example of the state of a pixel circuit when the reset of the anode is canceled in the second embodiment of the present technology.

[0057] Figure 32 It is a circuit diagram showing an example of the state of a pixel circuit when an error is held in the second embodiment of the present technology.

[0058] Figure 33 It is a circuit diagram showing an example of the state of a pixel circuit when the reset of the cathode is canceled in the second embodiment of the present technology.

[0059] Figure 34 It is a circuit diagram showing an example of the state of a pixel circuit when an excessive bias voltage is applied in the second embodiment of the present technology.

[0060] Figure 35 It is a circuit diagram showing an example of a pixel circuit in a standby state in the second embodiment of the present technology.

[0061] Figure 36 It is a timing diagram showing an example of the fluctuations of the cathode potential and a pulse signal in the second embodiment of the present technology.

[0062] Figure 37 It is a flowchart showing an example of the operation of a solid-state imaging device in the first embodiment of the present technology.

[0063] Figure 38 It is a block diagram showing an example of the schematic configuration of a vehicle control system.

[0064] Figure 39 It is a diagram showing an example of the installation position of the imaging unit. Detailed implementation manners

[0065] Hereinafter, the modes for implementing the present technology (hereinafter referred to as embodiments) will be described. The description will be given in the following order.

[0066] 1. First Embodiment (Example of adjusting the reverse bias of each pixel by a separate bias potential)

[0067] 2. Second Embodiment (Example of adjusting the reverse bias of each pixel by a potential corresponding to the error from the breakdown voltage)

[0068] 3. Application Example of a Moving Body

[0069] <1. First Embodiment>

[0070] [Configuration Example of Distance Measurement Module]

[0071] Figure 1 It is a block diagram showing a configuration example of the distance measurement module 100 in the first embodiment of the present technology. The distance measurement module 100 measures the distance to an object and includes a light emitting unit 110, a synchronization control unit 120, and a solid-state imaging element 200. The distance measurement module 100 is installed on a smart phone, a personal computer, a vehicle-mounted device, etc., and is used to measure the distance. It should be noted that the device on which the distance measurement module 100 is installed is an example of the electronic device described in the claims.

[0072] The synchronization control unit 120 operates the light emitting unit 110 and the solid-state imaging element 200 in synchronization with each other. The synchronization control unit 120 supplies a clock signal of a predetermined frequency (for example, 10 to 20 MHz) as a light emission control signal CLKp to the light emitting unit 110 and the solid-state imaging element 200 via signal lines 128 and 129, respectively.

[0073] The light emitting unit 110 supplies intermittent light as irradiation light in synchronization with the light emission control signal CLKp from the synchronization control unit 120. For example, near-infrared light or the like is used as the irradiation light.

[0074] The solid-state imaging element 200 receives the reflected light of the irradiation light to measure the round-trip time from the light emission timing indicated by the light emission control signal CLKp to the timing of receiving the reflected light. The solid-state imaging element 200 calculates the distance from each pixel to the object from the round-trip time, and generates and outputs a distance image in which distance data indicating the distance is arranged. It should be noted that the solid-state imaging element 200 is an example of the sensing device described in the claims.

[0075] [Configuration Example of Solid-State Imaging Element]

[0076] Figure 2 This is a diagram showing an example of the stacked structure of the solid-state imaging device 200 in the first embodiment of the present technology. The solid-state imaging device 200 includes a circuit chip 202 and a pixel chip 201 stacked on the circuit chip 202. These chips are electrically connected by connectors such as vias. Note that the chips can also be connected to each other by Cu-Cu bonding or bumps instead of by vias.

[0077] Figure 3 This is a block diagram showing an example of the configuration of the solid-state imaging device 200 in the first embodiment of the present technology. The solid-state imaging device 200 includes a reference voltage supply unit 210, a control circuit 221, a pixel array unit 222, a measurement value storage unit 223, a bias voltage setting unit 224, a signal processing unit 230, and a common bias circuit 240. In addition, in the pixel array unit 222, a plurality of pixels 300 are arranged in a two-dimensional lattice pattern.

[0078] The reference voltage supply unit 210 supplies a reference voltage VREF for each pixel individually. The control circuit 221 drives the rows in sequence to output a pulse signal.

[0079] The pixel 300 uses a SPAD to detect the presence of photons. The pixel 300 outputs a pulse signal indicating the detection result to the signal processing unit 230.

[0080] The signal processing unit 230 calculates the distance by measuring the round-trip time of each pixel based on the pulse signal from the pixel 300 and the light emission control signal CLKp from the synchronization control unit 120. The signal processing unit 230 generates a distance image in which distance data indicating the distance is arranged, and outputs the distance image to the outside.

[0081] The measurement value storage unit 223 holds a digital signal representing the measurement value of the breakdown voltage of the SPAD in each pixel for each pixel. In addition, in the measurement value storage unit 223, a target value to be used for the calculation of the bias voltage setting unit 224 and the measurement value are held. The target value will be described later. As the measurement value storage unit 223, for example, a non-volatile memory or a register is used.

[0082] The bias voltage setting unit 224 reads out the measurement value and the target value of each pixel from the measurement value storage unit 223, and sets the output voltage of each of the reference voltage supply unit 210 and the common bias circuit 240 based on the read values.

[0083] The common bias circuit 240 supplies a predetermined common bias potential as the anode potential VA to all pixels.

[0084] [Configuration Example of Pixel and Common Bias Circuit]

[0085] Figure 4 This is a circuit diagram showing an example of the configuration between the pixel 300 and the common bias circuit 240 in the first embodiment of the present technology. Each pixel 300 includes an individual bias circuit 310 and a pixel circuit 320.

[0086] The individual bias circuit 310 generates a potential corresponding to the reference voltage VREF as an individual bias potential VE from the reference voltage supply unit 210, and supplies the generated individual bias potential VE to the pixel circuit 320 in the same pixel. The reference voltage supplied to the pixel 300 in the x-th row (where x is an integer from 1 to X) and the y-th column (where y is an integer from 1 to Y) will be represented by VREFxy. Note that the individual bias circuit 310 of each pixel is an example of each of the first bias circuit and the second bias circuit described in the claims.

[0087] The individual bias circuit 310 includes an operational amplifier 311, a p-channel metal oxide semiconductor (pMOS) transistor 312, and a current source 313. The pMOS transistor 312 and the current source 313 are connected in series with each other between the power supply voltage VDDH and the reference potential VSSH.

[0088] In addition, one of the two input terminals of the operational amplifier 311 is connected to the reference voltage supply unit 210, and the other of the two input terminals of the operational amplifier 311 is connected to the connection node between the pMOS transistor 312 and the current source 313. The output terminal of the operational amplifier 311 is connected to the gate of the pMOS transistor 312. In addition, the potential of the connection node between the pMOS transistor 312 and the current source 313 is supplied as the individual bias potential VE to the detection circuit 330. Hereinafter, the individual bias potential of the pixel 300 in the x-th row and the y-th column will be represented by VExy.

[0089] The pixel circuit 320 includes a detection circuit 330 and a SPAD 340. The detection circuit 330 includes a driving transistor 331 and a logic gate 332.

[0090] The driving transistor 331 disconnects or closes the path between the cathode of the SPAD 340 and the node of the individual bias potential VExy according to the driving signal GAT from the control circuit 221. When driving the pixel circuit 320 in Geiger mode, the control circuit 221 controls the driving transistor 331 to the closed state using the driving signal GAT.

[0091] The logic gate 332 generates a pulse signal PDET indicating the result of detecting the presence of photons based on the cathode potential VC of the SPAD 340. For example, an inverter is used as the logic gate 332. For example, when the cathode potential VC is below a specified threshold, the logic gate 332 outputs a high-level pulse signal PDET to the signal processing unit 230, and when the cathode potential VC exceeds the specified threshold, the logic gate 332 outputs a low-level pulse signal PDET to the signal processing unit 230.

[0092] Hereinafter, let GATx denote the drive signal of the x-th row, and let VCxy and PDETxy denote the cathode potential and the pulse signal of the pixel 300 of the x-th row and the y-th column, respectively.

[0093] In addition, the common bias circuit 240 includes a current source 241, an nMOS transistor 242, and an operational amplifier 243. The current source 241 and the nMOS transistor 242 are connected in series with each other between the power supply voltage VDDH and the reference potential VSSH.

[0094] In addition, the reference voltage VAREF from the bias voltage setting unit 224 is input to one of the two input terminals of the operational amplifier 243, and the other of the two input terminals of the operational amplifier 243 is connected to the connection node between the current source 241 and the nMOS transistor 242. The output terminal of the operational amplifier 243 is connected to the gate of the nMOS transistor 242. In addition, the potential of the connection node between the current source 241 and the nMOS transistor 242 is supplied as a common bias potential (i.e., the anode potential VA) to the anodes of the SPAD 340s of all the pixels.

[0095] With the above configuration, in each pixel, the individual bias circuit 310 generates an individual bias potential VE corresponding to the reference voltage VREFxy and supplies the generated individual bias potential VE to the corresponding pixel circuit 320. In addition, the common bias circuit 240 supplies a common bias potential (anode potential VA) corresponding to the reference voltage VAREF to the anodes of the SPAD 340s of all the pixels.

[0096] In addition, in the Geiger mode, the voltage between the individual bias potential VExy and the anode potential VA is applied as the reverse bias voltage between the anode and the cathode of the SPAD 340. Then, when photons are incident on the pixel 300 in a state where the reverse bias voltage is applied thereto, the SPAD 340 multiplies the charge obtained by photoelectrically converting the photons in the avalanche to generate a photocurrent. When the cathode potential VCxy of the SPAD 340 drops and becomes equal to or less than the threshold according to the photocurrent, the logic gate 332 detects the photons and outputs a high-level pulse signal PDETxy.

[0097] Here, the pixel can change the breakdown voltage of the SPAD340 according to a process or temperature change. Due to the change in the breakdown voltage, the pixel changes in terms of photon detection efficiency (PDE). Therefore, the individual bias circuit 310 supplies an individual bias potential VE corresponding to the measured breakdown voltage of the corresponding pixel. For example, the lower the breakdown voltage, the lower the value to which the individual bias potential VE is adjusted. The individual bias potential enables the application of a reverse bias voltage having a value corresponding to the breakdown voltage, thereby correcting the change in the PDE of each pixel.

[0098] It should be noted that the detection circuit 330 can detect the presence of photons based on the potential of the cathode of the SPAD340, but can also detect the presence of photons based on the potential of the anode of the SPAD340.

[0099] Figure 5 FIG. 7 is a diagram showing an example of the arrangement of circuits and elements of each chip in the first embodiment of the present technology. In the pixel chip 201, the SPAD340 is arranged for each pixel. On the other hand, in the circuit chip 202 on which the pixel chip 201 is arranged, the individual bias circuit 310 and the detection circuit 330 corresponding to the SPAD340 are arranged below each SPAD340.

[0100] [Configuration example of signal processing unit]

[0101] Figure 6 FIG. 14 is a block diagram showing a configuration example of the signal processing unit 230 in the first embodiment of the present technology. The signal processing unit 230 includes a time - to - digital converter (TDC) 231 and a distance data generation unit 232 for each column.

[0102] The TDC 231 measures the time from the light emission timing indicated by the light emission control signal CLKp to the start of the generation of the pulse signal PDET from the corresponding column (i.e., the light reception timing). The TDC 231 supplies a digital signal representing the measured time to the distance data generation unit 232.

[0103] The distance data generation unit 232 calculates the distance D to the object. The distance data generation unit 232 obtains, for each cycle, the mode value among the times measured in each cycle of the TDC 231 as the round - trip time dt based on the vertical synchronization signal VSYNC having a frequency (e.g., 30 Hz) lower than that of the light emission control signal CLKp. Then, the distance data generation unit 232 uses the following formula to calculate the distance D and generates distance data representing the distance D. The data arranging the distance data of each pixel is output as a distance image.

[0104] D = c×dt / 2

[0105] In the above equation, c is the speed of light, and its unit is meters per second (m / s). Additionally, the unit of distance D is, for example, meters (m), and the unit of round-trip time dt is, for example, seconds (s).

[0106] Figure 7 is a timing chart showing an example of the fluctuations in the cathode potential and the pulse signal in the first embodiment of the present technology. In the initial state of the Geiger mode, a separate bias potential VE is applied to the cathode of the SPAD340. In this way, the cathode potential VC becomes the separate bias potential VE. The anode potential VA of all pixels is lower than the reference potential VSSH. At this time, the voltage between the separate bias potential VE and the anode potential VA is applied as the reverse bias voltage VAC between the anode and cathode of the SPAD340. When avalanche breakdown occurs, the reverse bias voltage VAC is set to a voltage having an absolute value larger than the absolute value of the breakdown voltage VBD. The difference between the breakdown voltage VBD and the reverse bias voltage VAC is referred to as the excess bias voltage VEX.

[0107] When a photon is incident at time T0, the SPAD340 multiplies the charge obtained by photoelectrically converting the photon in the avalanche to generate a photocurrent. The cathode potential VC of the SPAD340 decreases according to the photocurrent. Then, when the cathode potential VC becomes lower than the threshold VT of the logic gate 332 at timing T1, the logic gate 332 outputs a high-level pulse signal PDET. In this way, the incidence of the photon is detected. The cathode potential VC drops to the bottom potential VS corresponding to the excess bias voltage VEX.

[0108] Then, when the cathode potential VC rises through recharge and exceeds the threshold VT at timing T2, the logic gate 332 returns the pulse signal PDET to the low level. The cathode potential VC returns to the initial separate bias potential VE at timing T3.

[0109] As described above, the breakdown voltage VBD of the pixel can vary according to processing or temperature changes. To observe the effects of the variations, a comparative example is presented in which the same potential VE’ is applied to the cathodes of all pixels instead of supplying the separate bias circuit 310.

[0110] Figure 8It is a timing chart showing an example of cathode potential fluctuations in the comparative example. Pay attention to three pixels at addresses (1, 1), (1, 2), and (1, 3). Assume that the breakdown voltage VBD11 at address (1, 1) is greater than the breakdown voltage VBD12 at address (1, 2), and the breakdown voltage VBD12 is greater than the breakdown voltage VBD13 at address (1, 3). In this case, since the initial potential VE’ of the anode between the pixels is the same (in other words, the reverse bias is the same), the excess bias voltage VEX11 at address (1, 1) is less than the excess bias voltage VEX12 at address (1, 2). Additionally, the excess bias voltage VEX12 is less than the excess bias voltage VEX13 at address (1, 3).

[0111] Due to the change in the excess bias voltage VEX, when photons are incident, the amount of decrease in the cathode potential VC11 at address (1, 1) is less than the amount of decrease in the cathode potential VC12 at address (1, 2). Furthermore, the amount of decrease in the cathode potential VC12 is less than the amount of decrease in the cathode potential VC13 at address (1, 3). As described above, in the comparative example, the change in the amount of decrease in the cathode potential results in a change in the PDE of each pixel.

[0112] Figure 9 It is a diagram showing an example of a distance image of sensitivity change in the comparative example. Figure 9 It shows the distance image 500 when light with uniform brightness is incident on all pixels. In the distance image 500, the pixel values are determined based on the PDE of the pixels. In Figure 9 it, pixels with high PDE are represented by light colors, and pixels with low PDE are represented by dark colors.

[0113] In the case where the breakdown voltage VBD of the pixels changes according to the process or temperature, the PDE changes between the pixels due to the influence of the breakdown voltage change. For example, the pixel at the lower left address (X, 1) has a low PDE, the pixel at the upper right address (1, Y) has a high PDE, and the PDE gradually increases from the lower left end to the upper right end. In the comparative example, the change in the PDE between the pixels is not corrected, and thus, this change causes light and dark distortion in the distance image. This distortion is called shadow noise.

[0114] Figure 10 It is a circuit diagram showing a configuration example of the reference voltage supply unit 210 in the first embodiment of the present technology. The reference voltage supply unit 210 includes a voltage dividing resistor network, where multiple nodes N are connected to each other via resistors 211. A node N is provided for each pixel, and the node at address (x, y) will be represented by N xy be denoted as.

[0115] To suppress the above-mentioned shadow noise, the distance measurement module 100 pre-measures the breakdown voltage VBD of each pixel during product shipment or the like. During the measurement, any one of the following three measurement methods is adopted.

[0116] (1) A method in which the breakdown voltage VBD of a corresponding pixel is measured by connecting a measurement circuit to the cathodes of the SPADs 340 of all pixels.

[0117] (2) A method of measuring the breakdown voltage VBD of some parts (e.g., four corners) of the pixel array unit 222 and estimating the breakdown voltage VBD of other parts of the pixel array unit 222.

[0118] (3) A method of separately preparing replica pixels for measurement to measure the breakdown voltage VBD.

[0119] The digital signal indicating the measured value of each pixel is held in the measured value storage unit 223. When activated, the bias voltage setting unit 224 reads out the measured value and the target value from the measured value storage unit 223, and sets the output voltage of each of the reference voltage supply unit 210 and the common bias circuit 240 based on the read values.

[0120] For example, as Figure 9 shown, in the case where the PDE gradually increases from the lower left address (X, 1) to the upper right address (1, Y), the breakdown voltage VBD is measured to gradually decrease from the lower left end to the upper right end. In this case, the bias voltage setting unit 224 supplies a predetermined input voltage VRB to the lower left node N X1 and supplies an input voltage VRA lower than the input voltage VRB to the upper right node N 1Y . These input voltages VRA and VRB are generated by, for example, a digital-to-analog converter (DAC).

[0121] Then, a divided voltage between the input voltage VRA and the input voltage VRB is generated at each node through a voltage-dividing resistor network. When the input voltage VRA is lower than the input voltage VRB, the divided voltage gradually decreases from the upper left end to the upper right end. The divided voltage at the node N xy is supplied as the reference voltage VREFxy to the individual bias circuit 310 at the address (x, y).

[0122] Note that the resistance value of each resistor 211 can be variable. When the resistance value is variable, the set value of the resistance value is held in the resistor or the like, and the resistance value is controlled based on the set value.

[0123] In addition, in the reference voltage supply unit 210, the reference voltage VREF of each pixel is generated by a voltage-dividing resistor network, but the reference voltage VREF can also be generated by a circuit other than the voltage-dividing resistor network.

[0124] Figure 11 is a diagram showing an example of setting the reference voltage VREF in the first embodiment of the present technology. In the case where the PDE gradually increases from the lower left address (X, 1) to the upper right address (1, Y), the reference voltage VREF is set to gradually increase from the upper right end to the lower left end.

[0125] Figure 12 is a timing diagram showing an example of the cathode potential fluctuation in the first embodiment of the present technology. As described in reference Figures 9 to 11 , since the reference voltage VREF is set to correspond to the breakdown voltage VBD, a separate bias potential VE corresponding to the breakdown voltage VBD is applied to the cathode of each pixel.

[0126] For example, assume that the breakdown voltage VBD11 at the address (1, 1) is greater than the breakdown voltage VBD12 at the address (1, 2), and the breakdown voltage VBD12 is greater than the breakdown voltage VBD13 at the address (1, 3). At this time, a single bias potential VE11 is supplied to the address (1, 1), and the single bias potential VE11 is greater than the single bias potential VE12 at the address (1, 2). In addition, a separate bias potential VE12 is provided to the address (1, 2), and the separate bias potential VE12 is greater than the separate bias potential VE13 at the address (1, 3).

[0127] By applying these separate bias potentials, the excess bias voltage VEX becomes substantially the same between pixels. Therefore, when photons are incident, the amount of decrease in the cathode potential is substantially the same between pixels, and the PDE is also substantially the same between pixels.

[0128] Figure 13 is a diagram showing an example of the sensitivity of each pixel in the distance image in the first embodiment of the present technology. Figure 9 shows the distance image 500 when light with uniform brightness is incident on all pixels.

[0129] In the case where the breakdown voltage VBD of the pixel changes, as in the comparative example, shadow noise appears, as shown in Figure 9 . In this regard, in the distance measurement module 100, the reference voltage VREF is set to a value corresponding to the breakdown voltage VBD of each pixel to adjust the bias potential, as shown in Figure 11 . As a result, as shown in Figure 13 , the PDE is uniform between pixels, thereby suppressing shadow noise. Therefore, the variation in the distance measurement accuracy in the distance image 501 can be reduced.

[0130] Figure 14This is a diagram for explaining the voltage control in the first embodiment of the present technology. Each pixel circuit 320 includes a SPAD 340 and a detection circuit 330. In Geiger mode, a reverse bias voltage is applied between the anode and cathode of the SPAD 340. The detection circuit 330 detects the presence of photons based on the potential of the cathode of the SPAD 340.

[0131] In addition, an individual bias circuit 310 is connected to each pixel circuit 320. The individual bias circuit 310 provides an individual bias potential VE (e.g., VE11 or VE12) to the corresponding pixel circuit 320. As described above, since different reference voltages VREF11 and VREF12 are provided to the respective individual bias circuits 310, the respective biases VE11 and VE12 are provided, and the output of the bias circuit is determined based on each reference voltage. On the other hand, the pixel circuits 320 of all pixels are commonly connected to a common bias circuit 240. The common bias circuit 240 provides a common bias potential as the anode potential VA to the anodes of the SPAD 340s of all pixels.

[0132] When the common bias potential (anode potential VA) is provided to the anodes of all pixels, for each pixel, an individual bias potential VE is provided to the cathode. For each pixel, the individual bias potential VE is controlled to a value corresponding to the breakdown voltage of the SPAD 340.

[0133] The circuit including the individual bias circuit 310 and the common bias circuit 240 for each pixel serves as a voltage control unit 305 that adjusts the reverse bias voltage between the anode and cathode of each pixel. By adjusting the reverse bias between the anode and cathode for each pixel, the variation in the PDE (in other words, sensitivity) of each pixel can be corrected to suppress shadow noise.

[0134] [Operation example of distance measurement module]

[0135] Figure 15 This is a flowchart showing an example of the measurement process at the time of shipment in the first embodiment of the present technology. For example, the measurement process at the time of shipment is performed at the time of shipment. The distance measurement module 100 measures the breakdown voltage VBD of each pixel (step S901), and writes the measured value together with the target value into the measurement value storage unit 223 (step S902). For example, the target value of the bottom potential VS and the target value of the excess bias voltage VEX are written into the measurement value storage unit 223. After step S902, the distance measurement module 100 ends the measurement process at the time of shipment.

[0136] Figure 16 This is a flowchart showing an example of the distance measurement process in the first embodiment of the present technology. For example, when a predetermined application for generating a distance image is executed after shipment, the distance measurement process is started.

[0137] The bias voltage setting unit 224 initializes the individual bias potential VE and the common bias potential (anode potential VA) (step S911). Then, the bias voltage setting unit 224 reads out the measured value of the breakdown voltage VBD of each pixel from the measurement value storage unit 223 (step S912), and reads out the target value VSt of the bottom potential VS (step S913).

[0138] The bias voltage setting unit 224 calculates the statistical value (average value VBD AV , sum, etc.) of the breakdown voltage VBD of the corresponding pixel, and sets the anode potential VA that satisfies the following equation by controlling the common bias circuit 240 (step S914).

[0139] VA = VSt - VBD AV … Equation 1

[0140] Moreover, the bias voltage setting unit 224 reads out the target value VEXt of the remaining bias voltage VEX (step S915). Then, the bias voltage setting unit 224 sets the individual bias potential VE of each pixel that satisfies the following formula by controlling the reference voltage supply unit 210 (step S916).

[0141] VExy = VSxy + VEXt

[0142] = (VA + VBDxy) + VEXt… Equation 2

[0143] The calculation result of Equation 1 is input to VA on the right side of Equation 2. In addition, the measured value of the breakdown voltage at the address (x, y) is input to VBDxy on the right side of Equation 2.

[0144] The common bias circuit 240 starts to provide the set anode potential VA (step S917), and the individual bias circuit 310 starts to provide the set individual bias potential VE (step S918). Then, the distance measurement module 100 starts to measure the distance (step S919). After step S919, the distance measurement module 100 ends the distance measurement process.

[0145] Note that although it has been described that the same anode potential VA is provided to all pixels, individual anode potentials corresponding to the breakdown voltage of each pixel can be provided to each pixel. In this case, a bias circuit similar to the common bias circuit 240 is provided to each pixel and connected to the anode of each pixel. Then, the following expression is used instead of Equation 1 to provide an individual anode potential for each pixel.

[0146] VAxy = VSt - VBDxy

[0147] As described above, according to the first embodiment of the present technology, since the voltage control unit 305 adjusts the reverse bias voltage of each pixel to a value corresponding to the breakdown voltage of each pixel, it is possible to correct the change in sensitivity caused by the change in the breakdown voltage of each pixel. By correcting the change in sensitivity, it is possible to suppress shadow noise and reduce the change in distance measurement accuracy in the distance image.

[0148] [First Variation Example]

[0149] In the first embodiment described above, the common bias circuit 240 applies a common bias potential to the anode. However, in this configuration, the common bias circuit 240 is required, and the circuit scale of the distance measurement module 100 increases accordingly. The first variation example of the first embodiment is different from the first embodiment in that the common bias circuit 240 is not arranged in the solid-state imaging element 200.

[0150] Figure 17 It is a circuit diagram showing a configuration example of the pixel 300 in the first variation example of the first embodiment of the present technology. In the first variation example of the first embodiment, the common bias circuit 240 is not arranged, and a predetermined anode potential VA is applied to the anodes of all the SPADs 340 of the pixels. By eliminating the common bias circuit 240, the circuit scale of the distance measurement module 100 can be reduced.

[0151] As described above, in the first variation example of the first embodiment of the present technology, since the common bias circuit 240 is eliminated, the circuit scale of the distance measurement module 100 can be reduced.

[0152] [Second Variation Example]

[0153] In the first variation example of the first embodiment described above, the voltage control unit 305 adjusts the respective bias potentials for each pixel. However, in this configuration, it is necessary to arrange a separate bias circuit 310 for each pixel, making it difficult to increase the number of pixels. The second variation example of the first embodiment is different from the first variation example of the first embodiment in that a separate bias circuit 310 is arranged for each pixel block in the solid-state imaging element 200.

[0154] Figure 18 It is a circuit diagram showing a configuration example of the pixel block 306 in the second variation example of the first embodiment of the present technology. In the second variation example of the first embodiment, the pixel array unit 222 is divided into a plurality of pixel blocks 306. In each pixel block 306, a predetermined number of pixel circuits 320 and one separate bias circuit 310 are arranged. For example, four pixel circuits 320 of 2 rows × 2 columns are arranged for each pixel block 306.

[0155] The individual bias circuit 310 is commonly connected to the pixel circuits 320 in the same pixel block 306 to provide an individual bias potential VE to those pixel circuits 320. In this way, the individual bias potential VE is adjusted for each pixel block 306. Since different reference voltages VREF are supplied to the respective pixel blocks, an individual bias VE is supplied to each pixel block, and the output of the bias circuit is determined based on the corresponding reference voltage.

[0156] Figure 19 A diagram showing a configuration example of circuits and elements of each chip in a second modification of the first embodiment of the present technology. As Figure 19 shown, a predetermined number (e.g., four) of detection circuits 330 and individual bias circuits 310 are arranged for each pixel block 306 in the circuit chip 202. In Figure 19 this, the area surrounded by the dotted line represents the area corresponding to the pixel block 306. By arranging the individual bias circuit 310 for each pixel block 306, the circuit scale of each pixel can be reduced compared with the case of arranging an individual bias circuit 310 for each pixel. As a result, it is easy to increase the number of pixels.

[0157] As described above, in the second modification of the first embodiment of the present technology, since the individual bias circuit 310 is arranged for each pixel block 306, the circuit scale can be reduced compared with the case of arranging an individual bias circuit 310 for each pixel.

[0158] [Third Modification]

[0159] In the first modification of the above-described first embodiment, the voltage control unit 305 adjusts the respective bias potentials for each pixel. However, in this configuration, it is necessary to arrange the individual bias circuit 310 for each pixel, making it difficult to increase the number of pixels. The third modification of the first embodiment is different from the first modification of the first embodiment in that the individual bias circuit 310 is arranged for each line in the solid-state imaging device 200.

[0160] Figure 20It is a circuit diagram showing a configuration example of a pixel block 306 in a third modification of the first embodiment of the present technology. In the third modification of the first embodiment, a plurality of lines are arranged in the pixel array unit 222. In each of these lines, pixel circuits 320 are arranged in a predetermined direction (e.g., horizontal direction). Moreover, a separate bias circuit 310 is arranged for each line. The separate bias circuits 310 are commonly connected to each of the pixel circuits 320 in the corresponding line to supply a separate bias potential VE to the pixel circuits 320. In this way, the separate bias potential VE is adjusted for each line. Note that the pixel circuits 320 may also be arranged for each row in the vertical direction. Since different reference voltages VREF are supplied to the corresponding lines, a separate bias VE is supplied to each line, and the output of the bias circuit is determined according to the corresponding reference voltage.

[0161] Figure 21 It is a diagram showing an arrangement example of circuits and elements of each chip in a third modification of the first embodiment of the present technology. As Figure 21 shown, a separate bias circuit 310 is arranged for each line in the circuit chip 202. In Figure 21 it, the area surrounded by the dashed line represents the area corresponding to the line. By arranging a separate bias circuit 310 for each line, compared with the case of arranging a separate bias circuit 310 for each pixel, the circuit scale of each pixel can be reduced. As a result, it is easy to increase the number of pixels.

[0162] It should be noted that, as Figure 21 shown, if the separate bias circuit 310 is arranged only on one side of the line, heat generated from the separate bias circuit 310 can be concentrated from that position. Since the PDE may change due to temperature fluctuations, it is preferable that the heat distribution on the chip is uniform.

[0163] Therefore, the separate bias circuit 310 can be arranged at a position where the heat distribution is not biased. For example, as Figure 22 shown, the separate bias circuit 310 can be arranged on both sides of each line. In this case, half of the pixels in the row are connected to the right separate bias circuit 310, and the remaining pixels are connected to the left separate bias circuit 310. Alternatively, the separate bias circuit 310 can be arranged at one of the two ends (e.g., the left end) of the odd lines, and the other separate bias circuit 310 can be arranged at the other of the two ends (e.g., the right end) of the even lines.

[0164] As described above, in the third modification of the first embodiment of the present technology, since a separate bias circuit 310 is arranged for each line, compared with the case of arranging a separate bias circuit 310 for each pixel, the circuit scale can be reduced.

[0165] [Fourth Modification]

[0166] In the first modification of the first embodiment described above, the separate bias circuit 310 supplies an independent bias potential VE to the cathode. However, the separate bias circuit 310 may also supply an independent bias potential to the anode. The fourth modification of the first embodiment is different from the first embodiment in that the separate bias circuit 310 supplies an independent bias potential to the anode in the solid-state imaging device 200.

[0167] Figure 23 FIG. 4 is a circuit diagram showing a configuration example of the pixel 300 in the fourth modification of the first embodiment of the present technology. In the fourth modification of the first embodiment, the separate bias circuit 310 supplies a separate bias potential VA (for example, VA11 or VA12) to the anode of the SPAD 340. Since different reference voltages VREF11 and VREF12 are supplied to the respective separate bias circuits 310, separate biases VA11 and VA12 are provided, and the output of the bias circuit is determined based on each reference voltage. In this way, the potential of the anode is adjusted for each pixel. On the other hand, a potential common to all pixels is applied as VE to the cathode.

[0168] Note that a common bias circuit 240 may be further added. In this case, the common bias circuit 240 supplies a common bias potential as VE to the cathodes of all pixels.

[0169] As described above, according to the fourth modification of the first embodiment of the present technology, since the separate bias circuit 310 supplies an independent bias potential to the anode, the potential of the anode can be adjusted for each pixel.

[0170] [Fifth Modification]

[0171] In the fourth modification of the first embodiment described above, the voltage control unit 305 adjusts the respective bias potentials for each pixel. However, in this configuration, it is necessary to arrange a separate bias circuit 310 for each pixel, making it difficult to increase the number of pixels. The fifth modification of the first embodiment is different from the fourth modification of the first embodiment in that a separate bias circuit 310 is arranged for each pixel block in the solid-state imaging device 200.

[0172] Figure 24 FIG. 5 is a circuit diagram showing a configuration example of the pixel block 306 in the fifth modification of the first embodiment of the present technology. The fifth modification of the first embodiment is different from the fourth modification in that the pixel array unit 222 is divided into a plurality of pixel blocks 306. In each pixel block 306, a predetermined number of pixel circuits 320 and one separate bias circuit 310 are arranged.

[0173] By arranging a separate bias circuit 310 for each pixel block 306, the circuit scale of each pixel can be reduced compared to the case where a separate bias circuit 310 is arranged for each pixel. As a result, it is easy to increase the number of pixels.

[0174] Note that a separate bias circuit 310 that provides a separate bias potential to the anode can be arranged for each line.

[0175] As described above, in the fifth modification of the first embodiment of the present technology, since the separate bias circuit 310 is arranged for each pixel block 306, the circuit scale can be reduced compared to the case where the separate bias circuit 310 is arranged for each pixel.

[0176] <2. Second Embodiment>

[0177] In the above first embodiment, the solid-state imaging device 200 sets a separate bias potential based on the breakdown voltage measured in advance at the time of shipment. However, the value of the breakdown voltage may fluctuate according to the temperature after shipment. The second embodiment is different from the first embodiment in that the solid-state imaging device 200 maintains an error in the breakdown voltage with respect to the target value for each pixel after shipment.

[0178] Figure 25 is a block diagram showing a configuration example of the solid-state imaging device 200 in the second embodiment of the present technology. In the second embodiment, the control circuit 221, the pixel array unit 222, and the signal processing unit 230 are arranged in the solid-state imaging device 200. In the pixel array unit 222, a plurality of pixels 300 are arranged in a two-dimensional lattice pattern.

[0179] Figure 26 is a circuit diagram showing a configuration example of the pixel 300 according to the second embodiment of the present technology. In the second embodiment, the SAPD 340 and the detection circuit 350 are arranged in the pixel 300. The detection circuit 350 includes a power reset switch 351, an anode reset switch 352, a capacitor 353, a low potential supply unit 354, a cathode reset switch 355, and an inverter 356.

[0180] The power reset switch 351 opens or closes the path between the potential VE and the cathode of the SPAD 340 according to the power reset signal RESH from the control circuit 221. For example, the power supply potential is used as the potential VE.

[0181] The capacitor 353 is inserted between the anode of the SPAD 340 and the low potential supply unit 354. The low potential supply unit 354 supplies a low potential VRLD lower than a predetermined reference potential (for example, 0 V) to one end of the capacitor 353. The other end of the capacitor 353 is connected to the anode of the SPAD 340.

[0182] The anode reset switch 352 opens or closes the path between both ends of the capacitor 353 according to the anode reset signal RESAN from the control circuit 221.

[0183] The cathode reset switch 355 disconnects or closes the path between the cathode of the SPAD 340 and the reference potential according to the cathode reset signal RESL from the control circuit 221.

[0184] For example, nMOS transistors are used as the power reset switch 351, the anode reset switch 352, and the cathode reset switch 355. In this case, each switch transitions to the closed state in response to a high-level signal and transitions to the open state in response to a low-level signal.

[0185] The inverter 356 generates a pulse signal PDET based on the potential of the cathode of the SPAD 340. Note that the inverter 356 is an example of the logic gate described in the claims.

[0186] Note that the control circuit 221 is an example of the voltage control unit described in the claims.

[0187] Figure 27 is a circuit diagram showing an example of the equivalent circuit of the SPAD 340 in the second embodiment of the present technology. The equivalent circuit of the SPAD 340 is represented by a circuit in which, for example, the switch 341, the internal resistor 342, and the breakdown voltage supply unit 343 are connected in series between the anode and the cathode.

[0188] The switch 341 transitions to the closed state to generate a photocurrent when photons are incident. The breakdown voltage supply unit 343 supplies the breakdown voltage.

[0189] According to Figure 27 the configuration shown in, when photons are incident, the switch 341 transitions to the closed state, and a photocurrent flows through the internal resistor 342. As a result, the potential of the cathode drops.

[0190] Figure 28 is a graph showing an example of the voltage-current characteristics of the SPAD 340 in the second embodiment of the present technology. In Figure 28 the horizontal axis represents the voltage applied between the anode and the cathode of the SPAD 340, and the vertical axis represents the photocurrent from the SPAD 340. In the case of operating in Geiger mode, a negative voltage, that is, a reverse bias voltage, is applied as the voltage between the anode and the cathode of the SPAD 340. When the reverse bias voltage is lower than a predetermined breakdown voltage, avalanche breakdown occurs in the SPAD 340, and the photocurrent is amplified. When a voltage several volts lower than the breakdown voltage is applied between the anode and the cathode, the gain in amplification becomes substantially infinite, and one photon can be detected.

[0191] Figure 29It is a timing diagram showing an example of the operation of the control circuit 221 in the second embodiment of the present technology. At timing T11 before moving to Geiger mode, the control circuit 221 provides a high-level anode reset signal RESAN during the pulse while setting the cathode reset signal RESL to a high level. At this time, the power supply reset signal RESH is at a low level.

[0192] For example, through the control at timing T1, a predetermined reference potential (e.g., 0 volts) is applied to the cathode of the SPAD 340.

[0193] Then, at timing T12 when the pulse period has passed, the anode of the SPAD 340 reaches a predetermined low potential VRLD (e.g., -24 volts). At this time, the voltage between the anode and the cathode (e.g., -24 volts) corresponds to the target value VBD0 of the breakdown voltage.

[0194] Then, at timing T13, the light-emitting unit 110 emits a test light for measuring the error of the breakdown voltage of each pixel with respect to the target value VBD0. When emitting the test light, an object with a uniform reflectivity (e.g., white paper) is provided in front of the distance measurement module 100 so that the light reflected by the object is incident on the solid-state imaging element 200. Alternatively, light from outside the distance measurement module 100 is blocked, and the test light from the light-emitting unit 110 is reflected in the distance measurement module 100 so that the reflected light is incident on the solid-state imaging element 200.

[0195] The cathode potential VC of the SPAD 340 rises due to the incident light and becomes, for example, -20 volts (V). Since no excessive bias voltage is applied, the breakdown voltage VBD m appears in each pixel between the anode and the cathode of the pixel. Due to fluctuations in processing or temperature, the pixels may vary in terms of the breakdown voltage VBD m However, for each pixel, the error of the breakdown voltage VBD m with respect to the target value VBD0 (e.g., +4 volts) is held in the capacitor 353.

[0196] Then, at timing T14, the control circuit 221 cancels the reset of the cathode by returning the cathode reset signal RESL to a low level.

[0197] At timing T15 immediately after timing T14, the control circuit 221 provides a high-level power supply reset signal RESH during the pulse. Through this control, a potential VE (e.g., 3 volts) is applied to the anode of the SPAD 340. The voltage between the potential VE and the reference potential (e.g., 3 volts) is the excessive bias voltage.

[0198] At timing T15, the anode of SPAD340 is maintained at a potential (e.g., -20 V) with an error (e.g., +4 V). Therefore, a reverse bias (e.g., 23 V) between the potential with an error (e.g., -20 V) and potential VE (e.g., 3 V) is applied between the anode and the cathode. That is, the reverse bias voltage is adjusted to correspond to the breakdown voltage VBD of each pixel. m value.

[0199] At timing T16, the control circuit 221 causes the power reset signal RESH to return to a low level. The pixel circuit 320 transitions to the Geiger mode waiting for photon incidence. When a photon is incident in the Geiger mode, the potential of the anode drops.

[0200] Figure 30 is a circuit diagram showing an example of the state of the pixel circuit 320 when the anode and the cathode are reset in the second embodiment of the present technology. Figure 30 shows Figure 29 the state of the pixel circuit 320 at timing T11 shown.

[0201] At timing T11, the control circuit 221 controls the power reset switch 351 to be in an open state using the power reset signal RESH. In addition, the control circuit 221 controls the anode reset switch 352 and the cathode reset switch 355 to be in a closed state using the anode reset signal RESAN and the cathode reset signal RESL, respectively.

[0202] When the cathode reset switch 355 is in a closed state, the cathode of SPAD340 is initialized to a reference potential (e.g., 0 V). In addition, when the anode reset switch 352 is in a closed state, a low potential VRLD (e.g., -24 V) is applied to the anode of SPAD340. At this time, the voltage (e.g., -24 V) applied between the anode and the cathode corresponds to the target value VBD0 of the breakdown voltage.

[0203] Figure 31 is a circuit diagram showing an example of the state of the pixel circuit when the reset of the anode is canceled in the second embodiment of the present technology. Figure 31 shows at Figure 29 the state of the pixel circuit 320 at timing T12 shown.

[0204] At timing T12, the control circuit 221 controls the anode reset switch 352 to be in an open state using the anode reset signal RESAN.

[0205] Figure 32 is a circuit diagram showing an example of the state of the pixel circuit 320 when maintaining an error in the second embodiment of the present technology. Figure 32 shows Figure 29 the state of the pixel circuit 320 at timing T13 shown.

[0206] At timing T13, the reflected light of the test light is incident. The anode potential VA of the SPAD340 rises due to the incident light and becomes, for example, -20 volts (V). Since no excessive bias voltage is applied, the breakdown voltage VBD m appears in each pixel between the anode and cathode of the pixel. For each pixel, the breakdown voltage VBD m The error (e.g., +4 V) relative to the target value VBD0 is held in the capacitor 353.

[0207] Figure 33 is a circuit diagram showing an example of the state of the pixel circuit 320 when the reset of the cathode is canceled in the second embodiment of the present technology. Figure 33 Shows at Figure 29 the state of the pixel circuit 320 at timing T14.

[0208] At timing T14, the control circuit 221 controls the cathode reset switch 355 to the off state using the cathode reset signal RESL to cancel the reset of the cathode.

[0209] Figure 34 is a circuit diagram showing an example of the state of the pixel circuit when an excessive bias voltage is applied in the second embodiment of the present technology. Figure 34 Shows at Figure 29 the state of the pixel circuit 320 at timing T15.

[0210] At timing T15, the control circuit 221 controls the power supply reset switch 351 to the closed state using the power supply reset signal RESH. By this control, a potential VE (e.g., 3 V) is applied to the anode of the SPAD340. The voltage (e.g., 3 V) between the potential VE and the reference potential is the excessive bias voltage VEX.

[0211] At timing T15, a reverse bias voltage (e.g., 23 V) between the potential with error (e.g., -20 V) and the potential VE (e.g., 3 V) is applied between the anode and cathode.

[0212] Figure 35 is a circuit diagram showing an example of the pixel circuit 320 in the standby state in the second embodiment of the present technology. Figure 35 Shows Figure 29 the state of the pixel circuit 320 at timing T16.

[0213] At timing T16, the control circuit 221 controls the power supply reset switch 351 to the off state using the power supply reset signal RESH. The pixel circuit 320 transitions to a state of waiting for photon incidence (i.e., Geiger mode).

[0214] Figure 36It is a timing chart showing an example of fluctuations in the cathode potential and the pulse signal in the second embodiment of the present technology. In Geiger mode, a reverse bias voltage VAC corresponding to the difference between the breakdown voltage VBD and the excess bias voltage VEX is applied between the anode and the cathode of the SPAD340.

[0215] When a photon is incident just before timing T20, an avalanche breakdown occurs in the SPAD340, and the cathode potential VC drops. When the cathode potential VC becomes below the threshold VT at timing T20, the detection circuit 350 outputs a high-level pulse signal PDET. Then, when the cathode potential VC rises due to charging and exceeds the threshold VT at timing T21, the detection circuit 350 returns the pulse signal PDET to the low level.

[0216] Figure 37 It is a flowchart showing an example of the operation of the solid-state imaging element in the first embodiment of the present technology. For example, before switching to Geiger mode, this operation is started.

[0217] First, the control circuit 221 controls both the anode reset switch 352 and the cathode reset switch 355 to the closed state to initialize the potentials of the anode and the reset (step S951).

[0218] The control circuit 221 controls the anode reset switch 352 to the open state to cancel the reset of the anode (step S952).

[0219] Then, when light is incident, the capacitor 353 holds the error of the breakdown voltage VBD m (step S953).

[0220] The control circuit 221 controls the cathode reset switch 355 to the open state to cancel the reset of the cathode (step S954). The control circuit 221 controls the power supply reset switch 351 to the closed state to apply the excess bias voltage VEX (step S955). The control circuit 221 controls the power supply reset switch 351 to the open state to transition to the standby state for photons (Geiger mode) (step S956). After step S956, a distance image is captured, and the operation of the solid-state imaging element 200 for capturing the distance image ends.

[0221] Note that any one of the first embodiment and the first to fifth modification examples of the first embodiment can be applied to the second embodiment. By adjusting the bias potential of each pixel, it is possible to further improve the correction accuracy of the change in PDE.

[0222] As described above, in the second embodiment of the present technology, since the control circuit 221 performs control to hold the breakdown voltage VBD in the capacitor 353 mThe error is detected and the potential corresponding to the error is applied to the anode, so that the reverse bias voltage can be adjusted to a value corresponding to the breakdown voltage VBD. m As a result, the shading noise caused by the variation in the breakdown voltage can be suppressed, and the variation in the distance measurement accuracy in the distance image can be reduced.

[0223] <3. Application Example of Moving Body>

[0224] The technology according to the present disclosure (this technology) can be applied to various products. For example, the technology according to the present disclosure can be implemented as a device installed on any type of moving body, such as a vehicle, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, or a robot.

[0225] Figure 38 FIG. XX is a block diagram showing an example of a schematic configuration of a vehicle control system, which is an example of a moving body control system to which the technology according to an embodiment of the present disclosure can be applied.

[0226] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. In Figure 38 the example shown, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside vehicle information detection unit 12030, an in-vehicle information detection unit 12040, and an integrated control unit 12050. In addition, as a functional configuration of the integrated control unit 12050, a microcomputer 12051, a sound / image output unit 12052, and an in-vehicle network interface (I / F) 12053 are illustrated.

[0227] The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 serves as a control device for a driving force generation device for generating a driving force of the vehicle, such as an internal combustion engine, a drive motor, etc., a driving force transmission mechanism for transmitting the driving force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, a braking device for generating a braking force of the vehicle, etc.

[0228] The vehicle body system control unit 12020 controls the operations of various devices provided on the vehicle body according to various programs. For example, the vehicle body system control unit 12020 serves as a control device for a keyless entry system, a smart key system, an electric window device, or various lights such as headlights, rear lights, brake lights, turn signals, fog lights, etc. In this case, radio waves or signals from various switches sent from a mobile device as a substitute for a key can be input to the main body system control unit 12020. The vehicle body system control unit 12020 receives these input radio waves or signals and controls the vehicle door lock device, the electric window device, the lights, etc.

[0229] The outside vehicle information detection unit 12030 detects information outside the vehicle including the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside vehicle information detection unit 12030. The outside vehicle information detection unit 12030 causes the imaging unit 12031 to capture an image outside the vehicle and receives the captured image. In addition, the outside vehicle information detection unit 12030 can also perform processing for detecting objects such as people, vehicles, obstacles, signs, words on the road surface, etc., or processing for detecting their distances based on the received image.

[0230] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of received light. The imaging unit 12031 can output the electrical signal as an image, or can output the electrical signal as information about the measured distance. In addition, the light received by the imaging unit 12031 can be visible light, or can be invisible light such as infrared light.

[0231] The in-vehicle information detection unit 12040 detects information about the inside of the vehicle. The in-vehicle information detection unit 12040 is connected, for example, to a driver state detection unit 12041 that detects the state of the driver. The driver state detection unit 12041 includes, for example, a camera that captures the driver. Based on the detection information input from the driver state detection unit 12041, the in-vehicle information detection unit 12040 can calculate the driver's fatigue or the driver's concentration, or can determine whether the driver is dozing off.

[0232] The microcomputer 12051 can calculate control target values for a driving force generation device, a steering mechanism, or a braking device based on information about the inside or outside of the vehicle obtained by the outside vehicle information detection unit 12030 or the in-vehicle information detection unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can execute cooperative control for implementing functions of an advanced driver assistance system (ADAS), which includes functions such as anti-collision or shock absorption for the vehicle, following driving based on a following distance, maintaining the vehicle speed of driving, warning of vehicle collision, warning of deviation of the vehicle from the lane, etc.

[0233] In addition, the microcomputer 12051 controls the driving force generating device, the steering mechanism, the braking device, etc. based on information about external or internal vehicle information obtained by the external vehicle information detection unit 12030 or the in-vehicle information detection unit 12040, and can perform cooperative control for autonomous driving, enabling the vehicle to automatically drive without relying on the driver's operation, etc.

[0234] In addition, the microcomputer 12051 can output a control command to the vehicle body system control unit 12020 based on information about the outside of the vehicle obtained by the external vehicle information detection unit 12030. For example, the microcomputer 12051 can perform cooperative control aimed at preventing glare by controlling the headlamp to change from high beam to low beam according to the position of the vehicle ahead or the oncoming vehicle detected by the external vehicle information detection unit 12030.

[0235] The sound / image output unit 12052 sends an output signal of at least one of sound and image to an output device that can visually or auditorily notify information to the vehicle occupants or the outside of the vehicle. In Figure 38 the example, the audio speaker 12061, the display unit 12062, and the instrument panel 12063 are shown as output devices. For example, the display unit 12062 may include at least one of an on-board display and a head-up display.

[0236] Figure 39 is a diagram showing an example of the installation position of the imaging unit 12031.

[0237] In Figure 39 it, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0238] The imaging units 12101, 12102, 12103, 12104, and 12105 are, for example, arranged at positions on the front nose, side mirrors, rear bumper, and rear door of the vehicle 12100 and at a position above the windshield inside the vehicle. The imaging unit 12101 arranged at the front nose inside the vehicle and the imaging unit 12105 arranged above the windshield mainly obtain images of the front of the vehicle 12100. The imaging units 12102 and 12103 arranged on the side mirrors mainly obtain images of the sides of the vehicle 12100. The imaging unit 12104 arranged on the rear bumper or rear door mainly obtains images of the rear of the vehicle 12100. The imaging unit 12105 arranged above the windshield inside the vehicle is mainly used to detect the vehicle ahead, pedestrians, obstacles, signals, traffic signs, lanes, etc.

[0239] Incidentally, Figure 39An example of the imaging ranges of the imaging units 12101 to 12104 is described. The imaging range 12111 represents the imaging range of the imaging unit 12101 set to the front nose. The imaging ranges 12112 and 12113 represent the imaging ranges of the imaging units 12102 and 12103 set to the side mirrors, respectively. The imaging range 12114 represents the imaging range of the imaging unit 12104 set to the rear bumper or the rear door. For example, a bird's-eye view image of the vehicle 12100 viewed from above is obtained by superimposing the image data imaged by the imaging units 12101 to 12104.

[0240] At least one of the imaging units 12101 to 12104 may have a function of obtaining distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0241] For example, the microcomputer 12051 can determine the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the temporal change of the distance (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104, and thereby extract the nearest three-dimensional object as the preceding vehicle, which specifically exists on the travel path of the vehicle 12100 and travels in substantially the same direction as the vehicle 12100 at a predetermined speed (e.g., equal to or greater than 0 km / h). In addition, the microcomputer 12051 can preset a following distance to maintain in front of the preceding vehicle, and perform automatic braking control (including following stop control), automatic acceleration control (including following start control), etc. Thus, it is possible to perform coordinated control for autonomous driving that enables the vehicle to automatically travel without relying on the driver's operation or the like.

[0242] For example, the microcomputer 12051 can classify three-dimensional object data related to a three-dimensional object into three-dimensional object data of a two-wheeled vehicle, a standard vehicle, a large vehicle, a pedestrian, a utility pole, and other three-dimensional objects based on the distance information obtained from the imaging units 12101 to 12104, extract the classified three-dimensional object data, and use the extracted three-dimensional object data for automatically avoiding obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that can be visually recognized by the driver of the vehicle 12100 and obstacles that are difficult for the driver of the vehicle 12100 to visually recognize. Then, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle. When the collision risk is equal to or higher than a set value and thus there is a possibility of collision, the microcomputer 12051 outputs a warning to the driver via the audio speaker 12061 or the display unit 12062, and performs forced deceleration or avoidance steering via the driving system control unit 12010. The microcomputer 12051 can thereby assist driving to avoid a collision.

[0243] At least one of the imaging units 12101 to 12104 can be an infrared camera that detects infrared rays. The microcomputer 12051 can identify a pedestrian, for example, by determining whether there is a pedestrian in the captured images of the imaging units 12101 to 12104. Such identification of a pedestrian is performed, for example, by a process of extracting feature points in the captured images of the imaging units 12101 to 12104 that are infrared cameras and by a process of performing pattern matching processing on a series of feature points representing the contour of an object to determine whether it is a pedestrian. When the microcomputer 12051 determines that there is a pedestrian in the captured images of the imaging units 12101 to 12104 and thus identifies the pedestrian, the sound / image output section 12052 controls the display section 12062 such that a square contour line for emphasis is displayed superimposed on the identified pedestrian. The sound / image output section 12052 can also control the display section 12062 such that an icon representing the pedestrian or the like is displayed at a desired position.

[0244] Examples of a vehicle control system to which the technology according to the present disclosure can be applied have been described above. The technology according to the present disclosure can be applied to the outboard vehicle information detection unit 12030 among the above components. Specifically, Figure 1 the distance measurement module 100 of can be applied to the outboard vehicle information detection unit 12030. By applying the technology according to the present disclosure to the outboard vehicle information detection unit 12030, shadow noise can be suppressed, and variations in distance measurement accuracy in the distance image can be reduced.

[0245] It should be noted that the above embodiments describe examples for embodying the present technology, and there is a corresponding relationship between the matters in the embodiments and the matters specifying the present invention in the claims. Similarly, there is a corresponding relationship between the matters specifying the present invention in the claims and the matters represented by the same terms as the matters specifying the present invention in the embodiments of the present technology. However, the present technology is not limited to the embodiments, and various modifications can be made to the embodiments without departing from its gist to embody it.

[0246] It should be noted that the effects described in this specification are only examples and not restrictive, and there may be other effects.

[0247] It should be noted that the present technology may also have the following configurations.

[0248] (1) A sensing device, comprising:

[0249] A predetermined number of pixel circuits, each pixel circuit including a photoelectric conversion element and a detection circuit, applying a predetermined reverse bias voltage between the anode and the cathode of the photoelectric conversion element, and the detection circuit detecting the presence of photons based on the potential of the anode or the cathode; and

[0250] A voltage control unit that adjusts the reverse bias voltage to a value corresponding to the breakdown voltage of the photoelectric conversion element of each pixel circuit.

[0251] (2) The sensing device according to (1), wherein

[0252] The voltage control unit includes a predetermined number of individual bias circuits, and the individual bias circuits are respectively connected to different pixel circuits to respectively provide a predetermined individual bias potential to one of the anode and the cathode.

[0253] (3) The sensing device according to (2), wherein

[0254] The voltage control unit further includes a common bias circuit commonly connected to a predetermined number of pixel circuits to supply a predetermined common bias potential to the other of the anode and the cathode.

[0255] (4) The sensing device according to (2) or (3), wherein

[0256] The individual bias circuit supplies the individual bias potential to the cathode.

[0257] (5) The sensing device according to (2) or (3), wherein

[0258] The individual bias circuit supplies the individual bias potential to the anode.

[0259] (6) The sensing device according to any one of (2) to (5), wherein

[0260] A pixel circuit and an individual biasing circuit are arranged in each of a predetermined number of pixels.

[0261] (7) The sensing device according to any one of (2) to (5), wherein

[0262] The predetermined number of pixel circuits are dispersedly arranged in a plurality of pixel blocks, and

[0263] The individual biasing circuit is arranged in each of the plurality of pixel blocks.

[0264] (8) The sensing device according to any one of (2) to (5), wherein

[0265] The predetermined number of pixel circuits are dispersedly arranged in a plurality of lines, and

[0266] The individual biasing circuit is arranged in each of the plurality of lines.

[0267] (9) The sensing device according to (8), wherein

[0268] The individual biasing circuit is arranged at a position where the thermal distribution in the pixel array unit is not biased.

[0269] (10) The sensing device according to any one of (2) to (9), further comprising:

[0270] A voltage-dividing resistor network in which a predetermined number of nodes are connected to each other via resistors, wherein,

[0271] The predetermined number of nodes are respectively connected to different individual biasing circuits, and

[0272] Each individual biasing circuit supplies an individual biasing voltage corresponding to a reference voltage, and the reference voltage is the voltage of each connected node.

[0273] (11) The sensing device according to (10), further comprising:

[0274] A measurement value storage unit that stores measurement values of breakdown voltages of the photoelectric conversion elements of each pixel circuit; and

[0275] A setting unit that sets a reference voltage based on the measurement values.

[0276] (12) The sensing device according to (1), wherein

[0277] The voltage control unit performs control to maintain the error of the breakdown voltage with respect to the target value of each pixel circuit in the detection circuit, and applies a potential corresponding to the error to the anode.

[0278] (13) The sensing device according to (12), wherein

[0279] The detection circuit includes:

[0280] A power reset switch that disconnects or closes the path between the cathode and the power supply potential;

[0281] A capacitor inserted between the anode and a low potential lower than a predetermined reference potential;

[0282] An anode reset switch that disconnects or closes the path between the two ends of the capacitor;

[0283] A cathode reset switch that disconnects or closes the path between the cathode and the reference potential; and

[0284] A logic gate that generates a pulse signal based on the potential of the cathode.

[0285] (14) The sensing device according to (13), wherein

[0286] The voltage control unit sequentially performs a reset control that makes the power reset switch enter the off state and makes the anode reset switch and the cathode reset switch enter the on state, a hold control that makes the power reset switch and the anode reset switch enter the on state and makes the cathode reset switch enter the off state to hold the error in the capacitor, and a bias control that makes the power reset switch enter the on state and makes the anode reset switch and the cathode reset switch enter the off state to supply an excessive bias to the cathode.

[0287] (15) An electronic device, including:

[0288] A light emitting unit that supplies predetermined irradiation light;

[0289] A predetermined number of pixel circuits, each pixel circuit including a photoelectric conversion element and a detection circuit, applying a predetermined reverse bias voltage between the anode and the cathode of the photoelectric conversion element, and the detection circuit detecting whether photons exist in the reflected light relative to the irradiation light based on the potential of the anode or the cathode; and

[0290] A voltage control unit that adjusts the reverse bias voltage to a value corresponding to the breakdown voltage of the photoelectric conversion element of each pixel circuit.

[0291] (16) A sensing device, including:

[0292] A first pixel circuit including a first photoelectric conversion element and a first detection circuit, and the first detection circuit detecting whether photons exist based on the potential of the anode or the cathode of the first photoelectric conversion element;

[0293] A second pixel circuit including a second photoelectric conversion element and a first detection circuit, and the first detection circuit detecting whether photons exist based on the potential of the anode or the cathode of the second photoelectric conversion element;

[0294] A first bias circuit connected to the anode or cathode of the first photoelectric conversion element;

[0295] A second bias circuit connected to the anode or cathode of the second photoelectric conversion element; and

[0296] A reference voltage supply unit that supplies different reference voltages to the first bias circuit and the second bias circuit respectively to supply potentials corresponding to the respective reference voltages.

[0297] List of reference numerals

[0298] 100 Distance measurement module

[0299] 110 Light emitting unit

[0300] 120 Synchronization control unit

[0301] 200 Solid-state imaging device

[0302] 201 Pixel chip

[0303] 202 Circuit chip

[0304] 210 Reference voltage supply unit

[0305] 211 Resistor

[0306] 221 Control circuit

[0307] 222 Pixel array unit

[0308] 223 Measurement value storage unit

[0309] 224 Bias voltage setting unit

[0310] 230 Signal processing unit

[0311] 231 TDC

[0312] 232 Distance data generation unit

[0313] 240 Common bias circuit

[0314] 241, 313 Current source

[0315] 242 nMOS transistor

[0316] 243, 311 Operational amplifier

[0317] 300 Pixel

[0318] 305 Voltage control unit

[0319] 306 Pixel block

[0320] 310 Separate Bias Circuit

[0321] 312 pMOS Transistor

[0322] 320 Pixel Circuit

[0323] 330, 350 Detection Circuit

[0324] 331 Driving Transistor

[0325] 332 Logic Gate

[0326] 340 SPAD

[0327] 341 Switch

[0328] 342 Internal Resistor

[0329] 343 Breakdown Voltage Supply Unit

[0330] 351 Power Reset Switch

[0331] 352 Anode Reset Switch

[0332] 353 Capacitor

[0333] 354 Low Potential Supply Unit

[0334] 355 Cathode Reset Switch

[0335] 356 Inverter

Claims

1. A sensing device, comprising: A predetermined number of pixel circuits, each pixel circuit including a photoelectric conversion element and a detection circuit, applying a predetermined reverse bias voltage between the anode and the cathode of the photoelectric conversion element, and the detection circuit detecting the presence of photons based on the potential of the anode or the cathode; A voltage control unit that adjusts the reverse bias voltage to a value corresponding to the breakdown voltage of the photoelectric conversion element of each pixel circuit, wherein the voltage control unit includes a predetermined number of individual bias circuits, and the individual bias circuits are respectively connected to different pixel circuits to respectively supply a predetermined individual bias potential to one of the anode and the cathode; and A voltage dividing resistor network in which a predetermined number of nodes are connected to each other via resistors, wherein a predetermined number of the nodes are respectively connected to different individual bias circuits, and each individual bias circuit supplies an individual bias voltage corresponding to a reference voltage, and the reference voltage is the voltage of each connected node.

2. The sensing device according to claim 1, wherein The voltage control unit further includes a common bias circuit commonly connected to a predetermined number of the pixel circuits to supply a predetermined common bias potential to the other of the anode and the cathode.

3. The sensing device according to claim 1, wherein The individual bias circuit supplies the individual bias potential to the cathode.

4. The sensing device according to claim 1, wherein The individual bias circuit supplies the individual bias potential to the anode.

5. The sensing device according to claim 1, wherein The pixel circuit and the individual bias circuit are arranged in each of a predetermined number of pixels.

6. The sensing device according to claim 1, wherein A predetermined number of the pixel circuits are dispersedly arranged in a plurality of pixel blocks, and the individual bias circuit is arranged in each of the plurality of pixel blocks.

7. The sensing device according to claim 1, wherein A predetermined number of the pixel circuits are dispersedly arranged in a plurality of lines, and The individual bias circuit is arranged in each of the plurality of lines.

8. The sensing device according to claim 7, wherein The individual bias circuit is arranged at a position where the thermal distribution in the pixel array unit is not biased.

9. The sensing device according to claim 1, further comprising: A measurement value storage unit that stores the measured value of the breakdown voltage of the photoelectric conversion element of each pixel circuit; And A setting unit that sets the reference voltage based on the measured value.

10. The sensing device according to claim 1, wherein The voltage control unit performs control to maintain the error of the breakdown voltage with respect to the target value of each pixel circuit in the detection circuit, and applies a potential corresponding to the error to the anode.

11. The sensing device according to claim 10, wherein The detection circuit includes: A power reset switch that disconnects or closes the path between the cathode and the power supply potential; A capacitor inserted between the anode and a low potential lower than a predetermined reference potential; An anode reset switch for opening or closing a path between both ends of the capacitor; A cathode reset switch for opening or closing a path between the cathode and the reference potential; and A logic gate for generating a pulse signal based on the potential of the cathode.

12. The sensing device according to claim 11, wherein The voltage control unit sequentially performs a reset control for turning the power supply reset switch to an off state and turning the anode reset switch and the cathode reset switch to an on state, a holding control for turning the power supply reset switch and the anode reset switch to an on state and turning the cathode reset switch to an off state to hold an error in the capacitor, and a bias control for turning the power supply reset switch to an on state and turning the anode reset switch and the cathode reset switch to an off state to supply an excessive bias to the cathode.

13. An electronic device, comprising: A light emitting unit for supplying predetermined irradiation light; A predetermined number of pixel circuits, each pixel circuit including a photoelectric conversion element and a detection circuit, applying a predetermined reverse bias voltage between the anode and the cathode of the photoelectric conversion element, and the detection circuit detecting whether photons exist in the reflected light with respect to the irradiation light based on the potential of the anode or the cathode; A voltage control unit for adjusting the reverse bias voltage to a value corresponding to the breakdown voltage of the photoelectric conversion element of each pixel circuit; And A voltage dividing resistor network in which a predetermined number of nodes are connected to each other via resistors, wherein a predetermined number of the nodes are respectively connected to different individual bias circuits, and each individual bias circuit supplies an individual bias voltage corresponding to a reference voltage, and the reference voltage is the voltage of each connected node.

14. A sensing device, comprising: A first pixel circuit including a first photoelectric conversion element and a first detection circuit, the first detection circuit detecting whether photons exist based on the potential of the anode or the cathode of the first photoelectric conversion element; A second pixel circuit including a second photoelectric conversion element and a first detection circuit, the first detection circuit detecting whether photons exist based on the potential of the anode or the cathode of the second photoelectric conversion element; A first bias circuit connected to the anode or the cathode of the first photoelectric conversion element; A second bias circuit connected to the anode or the cathode of the second photoelectric conversion element; A reference voltage supply unit for respectively supplying different reference voltages to the first bias circuit and the second bias circuit to supply potentials corresponding to the respective reference voltages; And A voltage dividing resistor network in which a predetermined number of nodes are connected to each other via resistors, wherein a predetermined number of the nodes are respectively connected to different individual bias circuits, and each individual bias circuit supplies an individual bias voltage corresponding to a reference voltage, and the reference voltage is the voltage of each connected node.

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