Light detection element and electronic device

Abstract

[Problem] To provide a light detection element and an electronic device capable of suppressing a decrease in measurement accuracy due to a temperature change. In order to solve the above-mentioned problem, provided is a light detection element comprising: a photodiode that performs photoelectric conversion on incident light and outputs a photocurrent; and a control circuit performing control to change a potential of one end of the photodiode according to a temperature associated with the photodiode.

Description

Technical Field

[0001] The present disclosure relates to a light detection element and an electronic device. Background Art

[0002] Generally, in an electronic device having a distance measurement function, a distance measurement method called a time-of-flight (ToF) method is known. The ToF method is a method of measuring a distance by irradiating an object with irradiation light from the electronic device and obtaining a round-trip time until the irradiation light is reflected and returned to the electronic device. For example, a ToF camera that detects reflected light using a single-photon avalanche diode (SPAD) has been proposed. A SPAD is a photodiode that has improved sensitivity by amplifying a photocurrent.

[0003] The SPAD is used in Geiger mode, in which a reverse bias is applied to a voltage equal to or higher than a specific voltage. In this Geiger mode, control is performed such that a constant potential is applied in a state where power is applied to the anode side and a resistor or a constant current is applied to the cathode side.

[0004] Citation List

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application No. 2019-75394 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in the SPAD, even when a constant potential is applied to the anode side, the voltage between the anode and the cathode varies according to temperature. For this reason, the voltage between the anode and the cathode changes, and the measurement accuracy may decrease.

[0009] The present disclosure provides a light detection element and an electronic device capable of suppressing a decrease in measurement accuracy caused by temperature changes.

[0010] Solutions to the Problems

[0011] To solve the above problems, a light detection element of the present invention includes: a photodiode that performs photoelectric conversion on incident light and outputs a photocurrent; and a control circuit that controls to change a potential of one end of the photodiode according to a temperature related to the photodiode.

[0012] When the temperature is higher, the control circuit can provide a lower potential to the anode of the photodiode.

[0013] The photodiode may be a SPAD that can operate in Geiger mode, the light detection element may further include a resistor having one end connected to the cathode of the photodiode, and a predetermined potential may be provided to the other end of the resistor.

[0014] It further includes a temperature detection circuit for detecting temperature, and the control circuit can control the potential according to the temperature detected by the temperature detection circuit.

[0015] It further includes a resistor with one end connected to the cathode of the photodiode, and the following controls can be performed: a first mode of controlling the potential according to temperature; a second mode in which when a photocurrent flows through the resistor, a lower potential is supplied to the anode of the photodiode because the bottom potential of the cathode is higher.

[0016] After stopping supplying the potential to the anode of the photodiode, the potential can be controlled in the first mode until a predetermined number of times.

[0017] The control circuit can control the potential in the second mode after controlling the potential in the first mode.

[0018] In the case where a predetermined potential in the cathode cannot be detected, the control circuit can control the potential in the first mode.

[0019] It further includes an arithmetic circuit for calculating the potential according to temperature, and the control circuit can control the potential based on the calculation result of the arithmetic circuit.

[0020] The arithmetic circuit can calculate the potential according to a predetermined coefficient and temperature.

[0021] The arithmetic circuit can also calculate the potential based on the difference between the initial bottom potential of the cathode and the target potential, where the initial bottom potential is the potential when the control in the second mode has started.

[0022] The arithmetic circuit can calculate the potential based on the temperature fluctuation per predetermined time.

[0023] It further includes a detection circuit that detects the minimum value of the cathode as the bottom potential when a photocurrent flows through the resistor and supplies the detected minimum value to the arithmetic circuit.

[0024] The detection circuit may include a smoothing circuit that performs a smoothing calculation including a predetermined number of bottom potentials before imaging, and the predetermined number of imaging times in the first mode may correspond to the predetermined number before imaging.

[0025] The predetermined number of imaging times in the first mode can be one time when activated.

[0026] It further includes a pixel array unit, in which a plurality of pixel circuits each including a resistor and a photodiode are arranged in a two-dimensional matrix, at least two of the temperature detection circuits can be configured at different positions of the elements in which the pixel array unit is configured, and the control circuit can perform control to change the potential of one end of each photodiode in the plurality of pixel circuits based on each temperature detected by each temperature detection circuit in the temperature detection circuits.

[0027] It further includes a pixel array unit, in which a plurality of pixel circuits each including a resistor and a photodiode are arranged in a two-dimensional matrix. Each of at least two pixel circuits among the plurality of pixel circuits may include a detection circuit, and the control circuit may perform control to change the potential of one end of each photodiode in the plurality of pixel circuits based on each potential detected by the detection circuit.

[0028] The arithmetic circuit and the control circuit may be integrally configured in the same element.

[0029] It further includes a power supply circuit that provides the potential of the anode of each of the plurality of pixel circuits, and the control circuit may control the power supply circuit.

[0030] According to the present disclosure, an electronic device is provided, which includes a light detection element and a light emitting unit, and the light emitting unit is configured to emit measurement light synchronized with the timing of changing the potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a block diagram showing a configuration example of a distance measurement module according to a first embodiment of the present technology.

[0032] Figure 2 is a block diagram showing a configuration example of a light detection element according to a first embodiment of the present technology.

[0033] Figure 3 is a diagram showing a configuration example of a pixel array unit and a control circuit according to the present embodiment.

[0034] Figure 4 is a diagram showing a circuit configuration example of an imaging pixel circuit.

[0035] Figure 5 is a diagram showing the temperature characteristics when a constant anode potential is applied to the anode of the photodiode.

[0036] Figure 6 is a diagram showing an example of the temperature characteristics of the cathode potential.

[0037] Figure 7 is a diagram showing a control example of the anode potential of the photodiode of the control circuit.

[0038] Figure 8 is a circuit diagram showing a configuration example of the control circuit.

[0039] Figure 9 is a diagram showing a control operation example of the light detection element.

[0040] Figure 10It is a diagram showing an example of the control operation of the photodetection element when the temperature monitoring value is not used as a comparative example.

[0041] Figure 11 It is a circuit diagram showing a configuration example of the monitoring pixel circuit and the VBD monitoring circuit.

[0042] Figure 12 It is a diagram showing an example of the operating characteristics of the VBD monitoring circuit.

[0043] Figure 13 It is a diagram showing an example of the operating characteristics of the VBD monitoring circuit when the temperature monitoring value is not used at high temperature.

[0044] Figure 14 It is a diagram showing the time change of the cathode potential when the temperature monitoring value is not used at high temperature.

[0045] Figure 15 It is a diagram showing an example of the operating characteristics of the VBD monitoring circuit when the temperature monitoring value is not used at low temperature.

[0046] Figure 16 It is a diagram showing the time change of the cathode potential when the temperature monitoring value is not used at low temperature.

[0047] Figure 17 It is a flowchart showing an example of the operation of the photodetection element of the present embodiment.

[0048] Figure 18 It is a diagram showing a configuration example of the pixel array unit and the arithmetic circuit according to the first modification of the first embodiment.

[0049] Figure 19 It is a diagram showing a configuration example of the pixel array unit and the arithmetic circuit according to the second modification of the first embodiment.

[0050] Figure 20 It is a block diagram showing a configuration example of the pixel array unit according to the second embodiment.

[0051] Figure 21 It is a diagram showing the time change of the cathode potential Vc and the anode potential of the photodiode.

[0052] Figure 22 It is a diagram showing an example of the temperature characteristics of the cathode potential Vc.

[0053] Figure 23 It is a flowchart showing an example of the operation of the photodetection element of the second embodiment.

[0054] Figure 24 It is a diagram showing a configuration example of the imaging element according to the second embodiment.

[0055] Figure 25 is a block diagram showing a configuration example of a pixel array unit according to a third embodiment.

[0056] Figure 26 is a diagram showing the time variations of the cathode potential Vc, the anode potential, and the temperature of a photodiode.

[0057] Figure 27 is a diagram showing an operation example of a photodiode in the case where a temperature change occurs.

[0058] Figure 28 is a diagram showing a configuration example of an imaging element according to a second embodiment.

[0059] Figure 29 is a block diagram showing a configuration example of a distance measurement module according to a fourth embodiment.

[0060] Figure 30 is a diagram showing the relationship between the anode-cathode voltage and the pixel sensitivity of an imaging pixel circuit.

[0061] Figure 31 is a diagram showing the relationship between the anode-cathode voltage and the distance error of an imaging pixel circuit.

[0062] Figure 32 is a diagram showing a configuration example of a light detection element according to a fourth embodiment.

[0063] Figure 33 is a diagram showing an example of performing control in the case where all flags except the activation time are set to 1.

[0064] Figure 34 is a diagram showing an example of performing control using the temperature T in the case where the VBD monitoring circuit is not functioning;

[0065] Figure 35 is a diagram showing a configuration example of the VBD monitoring circuit 2 according to a fourth embodiment.

[0066] Figure 36 is a flowchart showing an example of a control process during a measurement operation according to the present embodiment.

[0067] Figure 37 is a diagram showing a configuration example of a pixel array unit and a control circuit according to a first modification of a fourth embodiment.

[0068] Figure 38 is a diagram showing a configuration example of a pixel array unit and a control circuit according to a second modification of a fourth embodiment.

[0069] Figure 39 FIG. is a diagram showing an example of a circuit configuration of the VBD monitoring circuit 2 according to the fifth embodiment.

[0070] Figure 40 FIG. is a diagram showing a change in the VBD monitoring value when the reaction count threshold is set to 1.

[0071] Figure 41 FIG. is a diagram showing a change in the VBD monitoring value when the reaction count threshold (in a slightly bright environment) is set to 1.

[0072] Figure 42 FIG. is a diagram showing a change in the VBD monitoring value when the reaction count threshold is set to 4.

[0073] Figure 43 FIG. is a diagram showing a change in the VBD monitoring value when the reaction count threshold (in a slightly bright environment) is set to 4.

[0074] Figure 44 FIG. is a flowchart showing an example of control processing during the measurement operation in the fifth embodiment.

[0075] Figure 45 FIG. is a block diagram showing an example of the configuration of a light detection element according to the sixth embodiment of the present technology.

[0076] Figure 46 FIG. is a flowchart showing an example of control processing according to the sixth embodiment.

[0077] Figure 47 FIG. is a block diagram showing an example of the configuration of a light detection element in the first modification of the sixth embodiment.

[0078] Figure 48 FIG. is a block diagram showing an example of the configuration of a light detection element in the second modification of the sixth embodiment.

[0079] Figure 49 FIG. is a block diagram showing an example of the configuration of an optical pixel array unit in the seventh embodiment of the present technology.

[0080] Figure 50 FIG. is a block diagram showing an example of the configuration of a light detection element according to the eighth embodiment.

[0081] Figure 51 FIG. is a diagram showing an example of the arrangement of a temperature monitoring circuit and a VBD monitoring circuit according to the sixth embodiment.

[0082] Figure 52 FIG. is a diagram showing an example of the arrangement of a temperature monitoring circuit and a VBD monitoring circuit according to the ninth embodiment.

[0083] Figure 53 is a diagram showing a configuration example of a pixel array unit according to the ninth embodiment.

[0084] Figure 54 is a block diagram showing a configuration example of a pixel array unit according to the tenth embodiment.

[0085] Figure 55 is a block diagram showing a configuration example of a pixel array unit according to the eleventh embodiment.

[0086] Figure 56 is a block diagram showing an example of a schematic configuration of a vehicle control system.

[0087] Figure 57 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit. Detailed Embodiments

[0088] Hereinafter, embodiments of a light detection element and an electronic device will be described with reference to the drawings. Hereinafter, the main components of the light detection element and the electronic device will be mainly described, but the light detection element and the electronic device may also have components or functions not shown. The following description does not exclude components and functions not depicted or described.

[0089] (First Embodiment)

[0090] [Configuration Example of Distance Measurement Module]

[0091] Figure 1 is a block diagram showing a configuration example of a distance measurement module 100 according to 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 control unit 120, and a light detection element 200. The distance measurement module 100 is mounted on an electronic device such as a smartphone, a personal computer, or a vehicle-mounted device and is used for measuring distance.

[0092] The control unit 120 controls the entire distance measurement module 100. For example, the control unit 120 synchronizes the operations of the light emitting unit 110 and the light detection element 200. The control unit 120 supplies a clock signal having a predetermined frequency (e.g., 10 to 20 MHz) as a light emission control signal CLKp to the light emitting unit 110 and the light detection element 200 via signal lines 128 and 129.

[0093] The light emitting unit 110 provides intermittent light as irradiation light in synchronization with the light emission control signal CLKp from the control unit 120. For example, near-infrared light or the like is used as the irradiation light.

[0094] The light detection element 200 receives the reflected light of the irradiated light, and measures 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 light detection element 200 calculates the distance to the object based on the round-trip time, and generates and outputs distance data representing the distance.

[0095] [Configuration example of light detection element]

[0096] Figure 2 is a block diagram showing a configuration example of the light detection element 200 according to the first embodiment of the present technology. The light detection element 200 includes a control circuit 210, an anode potential supply power source 220, a signal processing unit 230, and a pixel array unit (sensor) 240. It should be noted that the control circuit 210 may also be configured in the control unit 120 (see Figure 1 ).

[0097] The control circuit 210 is, for example, an application processor (AP), and can control the potential of each pixel circuit in the pixel array unit 240. Details of the control circuit 210 will be described later.

[0098] The anode potential supply power source 220 supplies the anode potential to the pixel circuits in the pixel array unit 240 under the control of the control circuit 210. Note that the anode potential supply power source 220 according to the present embodiment corresponds to a power supply circuit.

[0099] The signal processing unit 230 measures the round-trip time of each pixel circuit based on the signal from the pixel circuit and the light emission control signal CLKp from the control unit 120, and calculates the distance. The signal processing unit 230 generates distance data representing the distance for each pixel circuit and outputs it to the outside.

[0100] In the pixel array unit 240, the imaging pixel circuits 250 and the monitoring pixel circuits 260 are arranged in a two-dimensional grid pattern. Details of the pixel array unit 240 will also be described later. In addition, the total number of the monitoring pixel circuits 260 and the pixel array unit 240 is N (N is an integer of 2 or more). In addition, at least one of the N pixel circuits is a monitoring pixel circuit 260, and the rest are imaging pixel circuits 250. Hereinafter, a group of pixel circuits arranged in the horizontal direction may be referred to as a "row", and a group of pixel circuits arranged in the direction perpendicular to the row may be referred to as a "column". It should be noted that the imaging pixel circuits 250 and the monitoring pixel circuits 260 according to the present embodiment correspond to pixel circuits. In addition, in this case, distance data is generated for each imaging pixel circuit 250.

[0101] [Configuration example of pixel array unit]

[0102] Figure 3FIG. is a diagram showing a configuration example of a pixel array unit and a control circuit according to the present embodiment. In the following description, in order to simplify the description, some configurations in the signal processing unit 230 and the imaging pixel circuit 250 may be omitted. It should be noted that the details of the imaging pixel circuit 250 will be described later with reference to Figure 4 , the details of the imaging pixel circuit 250 are described.

[0103] As Figure 3 shown, the pixel array unit (sensor) 240 includes a plurality of imaging pixel circuits 250, a monitoring pixel circuit 260, a VBD monitoring circuit 270, a temperature monitoring circuit 280, a storage unit (memory) 290, and an arithmetic circuit 300. In addition, the arithmetic circuit 300 includes an anode potential absolute value calculation unit 301 and an anode potential adjustment amount calculation unit 302. It should be noted that the details of the control circuit 210 will be described later with reference to Figure 8 . In addition, in the present embodiment, the control circuit 210 and the arithmetic circuit 300 are separately configured, but the present invention is not limited thereto. For example, the control circuit 210 and the arithmetic circuit 300 may be integrally configured as one element. In this case, the arithmetic circuit 300 may be configured without the control circuit 210. Alternatively, the control circuit 210 may be configured without the arithmetic circuit 300. In addition, the control circuit 210 and the arithmetic circuit 300 configured as one element may be configured without the pixel array unit 240. Alternatively, the control circuit 210 and the arithmetic circuit 300 configured as one element may be configured outside the pixel array unit 240.

[0104] Here, examples of the imaging pixel circuit 250 and the temperature characteristics of the imaging pixel circuit 250 will be described with reference to Figure 4 and Figure 5 . Figure 4 FIG. is a diagram showing a circuit configuration example of the imaging pixel circuit 250. As Figure 4 shown, the imaging pixel circuit 250 includes a resistor 251, a photodiode 252, an inverter 271, and a transistor 273.

[0105] Figure 5 FIG. is a diagram showing temperature characteristics when a constant anode potential Vacon is applied to the anode of the photodiode 252. (a) of the figure is a diagram showing the cathode potential Vc in the case where a constant anode potential Vacon is applied to the anode of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time.

[0106] FIG. (b) is a diagram showing the output signal of the inverter 271. The vertical axis represents the signal level, and the horizontal axis represents time. FIG. (c) is a diagram showing an example of a histogram of the rise time of the pulse generated by the signal processing unit 230. The vertical axis represents the frequency, and the horizontal axis represents time. In the present embodiment, the measurement object is irradiated with the measurement light a plurality of times. Therefore, the signal processing unit 230 generates the rise times of a plurality of pulses.

[0107] As Figure 4 shown, one end of the resistor 251 is connected to the cathode of the photodiode 252, and the other end is connected to the terminal of the potential VE. When the reflected light is incident, the photodiode 252 photoelectrically converts the incident light and outputs a photocurrent. For example, an SPAD is used as the photodiode 252. Further, the anode potential supplied from the power supply 220 to the anode of the photodiode 252 is controlled by the control circuit 210.

[0108] As Figure 5 shown in (a), when the reflected light is incident, the photocurrent from the photodiode 252 flows through the resistor 251, and the cathode potential Vc drops from the potential VE according to the current value. When a constant anode potential Vacon is applied to the anode of the photodiode 252, as shown by the line L100 in the cathode potential Vc at the time of high-temperature activation of the photodiode 252, the voltage drop of the cathode potential Vc becomes small. On the other hand, when a constant anode potential Vacon is applied to the anode of the photodiode 252, at the time of low-temperature activation of the photodiode 252, the voltage drop of the cathode potential Vc becomes large, as shown by the line L102 in the cathode potential Vc.

[0109] In the present embodiment, the minimum value of the cathode potential Vc is referred to as the bottom potential Vbtm. The voltage of the difference between the constant anode potential Vacon of the photodiode 252 and the bottom potential Vbtm is referred to as the breakdown voltage VBD.

[0110] The inverter 271 inverts the signal of the cathode potential Vc of the photodiode 252 and outputs it as a pulse signal OUT to the signal processing circuit 230. As shown in FIG. (b), the inverter 271 outputs the pulse signals L104 and L106 at a low level when the cathode potential Vc is higher than a predetermined threshold Vth, and outputs the pulse signals L104 and L106 at a high level when the cathode potential Vc is equal to or lower than the threshold. The pulse signal L104 corresponds to high-temperature activation, and the pulse signal L106 corresponds to low-temperature activation.

[0111] As shown in (c) of the figure, the signal processing unit 230 can detect the timing of the statistical value based on the rise of the pulse signal OUT as the optical reception timing based on the rising histograms of the pulse signals L104 and L106. The histogram signal L108 corresponds to high-temperature activation, and the histogram signal L110 corresponds to low-temperature activation.

[0112] When the photodiode 252 is an SPAD, the SPAD is used in the Geiger mode, in which a reverse bias voltage is applied to a voltage equal to or higher than a specific voltage. Then, when light is detected, due to impact ionization, the anode-cathode voltage VEX drops to the quenching voltage (the voltage at which the bottom potential Vbtm is generated), and the photodiode 252 changes from a high-impedance state to a low-impedance state. The light detection element 200 can create ToF data by detecting the change in the cathode potential at this time, for example, with respect to a threshold value Vth. When the anode-cathode voltage drops to the quenching voltage, the photodiode 252 again becomes high-impedance and is switched back to the Geiger mode by the pull-up due to the high impedance.

[0113] Accordingly, when the temperature at activation is different, the falling characteristic of the cathode potential Vc varies, and the quenching voltage varies. Therefore, the detection distance changes. Thus, in the present embodiment, the temperature is measured by the temperature monitoring circuit 280, and the anode potential of the photodiode 252 is controlled so that the bottom potential Vbtm of the photodiode 252 at activation becomes close to the target potential Vtarget regardless of the temperature.

[0114] As Figure 3 shown, similar to the imaging pixel circuit 250, the monitoring pixel circuit 260 includes a resistor 251 and a photodiode 252. Similar to the imaging pixel circuit 250, when reflected light is incident, the photocurrent from the photodiode 252 flows through the resistor 251, and the cathode potential Vc drops according to the current value.

[0115] The VBD monitoring circuit 270 monitors the signal of the cathode potential Vc of the photodiode 252 in the pixel circuit 260. More specifically, the VBD monitoring circuit 270 samples the cathode potential Vc (i.e., the bottom potential Vbtm) of the region including the lowermost part of the cathode potential Vc. The VBD monitoring circuit 270 outputs the sampled bottom potential Vbtm to the anode potential adjustment amount calculation unit 302 of the arithmetic circuit 300. In addition, the details of the VBD monitoring circuit 270 will be described later.

[0116] The temperature monitoring circuit 280 monitors the temperature of the photodiode 252 in the pixel circuit 260. For example, the temperature monitoring circuit 280 is a temperature sensor arranged in the pixel array unit 240. The temperature monitoring circuit 280 can monitor the temperature of the photodiode 252 considering, for example, the temperature gradient in the pixel array unit 240 and the like. The temperature monitoring circuit 280 outputs the measured temperature value to the anode potential absolute value calculation unit 302 of the arithmetic circuit 300. Note that the temperature monitoring circuit 280 according to the present embodiment corresponds to the temperature detection circuit.

[0117] The storage unit (memory) 290 stores the individual value temperature coefficient α in the photodiode 252. Figure 6 It is a diagram showing an example of the temperature characteristics of the cathode potential Vc. The vertical axis represents the breakdown voltage VBD of the photodiode 252, and the horizontal axis represents the temperature. The temperature characteristic line VBD(T) of the breakdown voltage has, for example, a linear characteristic with respect to the temperature. Note that in the present embodiment, the temperature characteristic line VBD(T) is described as linear, but the present invention is not limited thereto. For example, a non-linear function can be used.

[0118] The slope of the temperature characteristic line VBD(T) is defined as the individual value temperature coefficient α. For example, the individual value temperature coefficient α can be measured by a test measurement at the time of shipment of the sensor. For example, the individual value acquisition temperature T0 at the time of shipment and the value VBD(T0) of the temperature characteristic line at this time are stored in the storage unit 290 as the VBD individual value VBD(T0). Since the individual value temperature coefficient α, the individual value acquisition temperature T0, and the VBD individual value VBD(T0) are stored, the temperature characteristic line VBD(T) at each temperature T can be obtained by linear calculation. Note that in the case of non-linearity, the temperature characteristic line VBD(T) can be stored in the storage unit 290 as a temperature table.

[0119] The anode potential absolute value calculation unit 301 of the arithmetic circuit 300 calculates the anode potential of the photodiode 252 using the monitored temperature value T of the temperature monitoring circuit 280, the individual value temperature coefficient α, the individual value acquisition temperature T0, and VBD and the individual value VBD(T0). That is, for example, as shown in Expression (1), the breakdown voltage VBD(T) at the temperature T is VBD(T0)+α×(T - T0). The anode potential of the photodiode 252 when the bottom potential Vbtm at the breakdown voltage VBD(T0) becomes the target potential Vtarget is set to (VE - Vtarget)-VBD(T0)+c. c is any constant including 0. Therefore, the anode potential abs having the bottom potential Vbtm at the breakdown voltage VBD(T) of the cathode potential at the temperature T as the target potential Vtarget is, for example, Expression (2).

[0120] That is, the absolute value calculation unit 301 of the anode potential calculates the anode potential abs of the photodiode 252 according to, for example, Expressions (1) and (2) such that the bottom potential Vbtm of the photodiode 252 becomes close to the target potential Vtarget when activated.

[0121] [Expression 1]

[0122] VBD(T) = VBD(T0) + α × (T - T0) (1)

[0123] [Expression 2]

[0124] abs = (VE - Vtarget) - VBD(T) + c (2)

[0125] As Figure 6 shown, the breakdown voltage VBD(T) increases as the temperature rises. Therefore, the anode potential abs decreases as the temperature rises.

[0126] On the other hand, the anode potential of the second and subsequent anodes is calculated by the anode potential adjustment amount calculation unit 302. The anode potential adjustment amount calculation unit 302 calculates the adjustment value delta of the anode potential according to Expression (3) using the bottom potential Vbtm monitored by the VBD monitoring circuit 270.

[0127] [Expression 3]

[0128] delta = (Vtarget - Vbtm) (3)

[0129] Figure 7 is a diagram showing a control example of the anode potential of the photodiode 252 of the control circuit 210. In Figure 7 it, as in Figure 5 (a) of, the vertical axis represents the cathode potential Vc, and the horizontal axis represents time. Here, the line L114 represents the cathode potential Vc.

[0130] The control circuit 210 has a first mode of controlling the anode potential according to the temperature T and a second mode of supplying a lower potential to the anode of the photodiode 252 when the bottom potential Vbtm is higher when a photocurrent flows through the resistor 251 (see Figure 3 ).

[0131] That is, in the first mode, as Figure 7As shown by line L114 in [description], when activated, control circuit 210 controls anode potential supply power source 220 using temperature T of temperature monitoring circuit 280 and individual value temperature coefficient α so as to have the anode potential abs of photodiode 252 (see expression (2)). Thus, bottom potential Vbtm of cathode potential Vc of photodiode 252 becomes close to target potential Vtarget.

[0132] On the other hand, in the second mode, during operation, control circuit 210 adds adjustment value delta (see expression (3)) to the previous bottom potential Vbtm using bottom potential Vbtm of VBD monitoring circuit 270. Thus, bottom potential Vbtm during the second and subsequent operations asymptotically approaches a value substantially the same as target potential Vtarget. As described above, in the second mode, control circuit 210 controls anode potential supply power source 220 by feedback control.

[0133] In this way, control circuit 210 controls the anode potential in the first mode when activated. The activation time is, for example, a case where the supply of the anode potential of photodiode 252 resumes after the supply of the anode potential stops. On the other hand, control circuit 210 controls the anode potential in the second mode during operation. During operation, it is a state where the anode potential of photodiode 252 is continuously supplied. That is, in the present embodiment, after controlling the anode potential in the first mode, the anode potential is controlled in the second mode.

[0134] Figure 8 is a circuit diagram showing a configuration example of control circuit 210. As Figure 8 shown, control circuit 210 includes selection circuit 211, holding circuit 212, and addition circuit 213.

[0135] For example, selection circuit 211 is a multiplexer, and anode potential absolute value calculation unit 301 is connected to the input terminal on the 0 side, and the output terminal of addition circuit 213 is connected to the input terminal on the 1 side. Further, the output terminal of selection circuit 211 is connected to anode potential supply power source 220 and one end of holding circuit 212. For example, selection circuit 211 selects and outputs the input signal of the input terminal on the 0 side or the input terminal on the 1 side according to the control signal of control unit 120.

[0136] For example, holding circuit 212 is a memory, and the other end of holding circuit 212 is connected to one input terminal of addition circuit 213. Holding circuit 212 holds the output value of selection circuit 211 while updating the output value. Anode potential adjustment amount calculation unit 302 is connected to the other input terminal of addition circuit 213.

[0137] (Operation when activated)

[0138] The selection circuit 211 outputs the anode potential abs of the photodiode 252, which is the input of the anode potential absolute value calculation unit 301 on the 0 side, to the anode potential supply power source 220 when the light detection element 200 is activated (see Equation (2)). Further, the holding circuit 212 holds the anode potential abs when activated. Accordingly, the anode potential supply power source 220 supplies the anode potential abs (see Expression (2)) to the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 when activated.

[0139] (Operation during operation)

[0140] The addition circuit 213 adds the input value from the holding circuit 212 and the adjustment value delta, which is the input from the anode potential adjustment amount calculation unit 302 (see Expression (3)), and outputs the result to the selection circuit 211. That is, the addition circuit 213 outputs a current control value obtained by adding the previous anode potential control value and the adjustment value delta.

[0141] The selection circuit 211 outputs the current control value output from the addition circuit 213 on the 1 side to the anode potential supply power source 220 when the light detection element 200 is operating. Accordingly, the bottom potential Vbtm asymptotically approaches a value substantially the same as the target potential Vtarget.

[0142] Figure 9 is a diagram showing an example of the control operation of the light detection element 200. (a) of the figure is a diagram schematically showing the control state. The horizontal axis represents time.

[0143] (b) of the figure represents the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. Here, the line L114a represents the cathode potential Vc during low-temperature activation, and the line L116a represents the cathode potential Vc during high-temperature activation. Further, the line L114b indicates the cathode potential Vc during the operation after low-temperature activation, and the line L116b indicates the cathode potential Vc during the operation after high-temperature activation.

[0144] (c) of the figure shows the anode potential of the photodiode 252. The vertical axis represents the anode potential, and the horizontal axis represents time. Here, the line L118a represents the anode potential during low-temperature activation, and the line L120a represents the anode potential during high-temperature activation. Further, the line L118b indicates the anode potential during the operation after low-temperature activation, and the line L120b indicates the anode potential during the operation after high-temperature activation.

[0145] (d) of the figure shows the anode current of the photodiode 252. The vertical axis represents the anode current, and the horizontal axis represents time. Here, the line L122a represents the anode current during low-temperature activation, and the line L124a represents the anode current during high-temperature activation. In addition, the line L122b indicates the anode current during the operation after low-temperature activation, and the line L124b indicates the anode current during the operation after high-temperature activation.

[0146] The operating state of (a) of the figure will be described. First, the light detection element 200 starts to be driven according to the control of the control unit 120 ( Figure 1 ). At this time, the anode potential supply power source 220 also starts to be driven (timing t10). Next, the temperature monitoring circuit 280 acquires a temperature monitoring value according to the synchronization timing of the control unit 120, and the anode potential absolute value calculation unit 301 calculates the anode potential abs (see Expression (2)) (timing t12). Subsequently, the control circuit 210 supplies the anode potential abs to the anode potential supply power source 220, and the anode potential supply power source 220 controls the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to the anode potential abs (time t14).

[0147] Next, in synchronization with the light emission of the light emitting unit 110, waiting for the generation of the photocurrent of the photodiode 252 (time t16), and the VBD monitoring circuit 270 acquires the cathode potential Vc after a predetermined time when the cathode potential Vc exceeds the threshold th (see Figure 5 ) as the bottom potential Vbtm (time t18). Subsequently, the control circuit 210 supplies the control value obtained by adding the adjustment value delta (see Expression (3)) to the bottom potential Vbtm to the anode potential supply power source 220, and the anode potential supply power source 220 controls the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to the control value (time t20). After that, the timings t16 to t20 are repeated until imaging is completed.

[0148] As shown in (c) of the figure, through the voltage control at time t14, the anode potential is controlled to a higher anode potential L118a during low-temperature activation, and the anode potential is controlled to a lower anode potential L120a during high-temperature activation. Therefore, as shown in (b) of the figure, in the cathode potential lines L114a and L116a, near the target potential Vtarget becomes the bottom potential Vbtm in both the case of low-temperature activation and the case of high-temperature activation. In addition, as shown in (d) of the figure, the anode currents I122a and L124a at this time have the same values in both the case of low-temperature activation and the case of high-temperature activation, and the error in distance measurement is suppressed.

[0149] Similarly, during operation, as shown in (c) of the figure, by voltage control at time t20, the anode potential is controlled to a higher anode potential L118b during low-temperature activation, and the anode potential is controlled to a lower anode potential L120b during low-temperature activation. Therefore, as shown in (b) of the figure, during low-temperature activation and during the operation after high-temperature activation, the bottom potential Vbtm of the cathode potential lines L114b and L116b becomes a value close to the target potential Vtarget. In addition, as shown in (d) of the figure, during low-temperature activation and during the operation after high-temperature activation, the anode currents I122b and L124b at this time also have the same value, and the error in distance measurement is suppressed.

[0150] Figure 10 is a diagram showing a control operation example of the photodetection element 200 when the temperature monitoring value is not used as a comparative example. (a) to (d) of the figure are similar to Figure 8 . (a) of the figure is a diagram schematically showing the operation state when the temperature monitoring value is used. The horizontal axis represents time.

[0151] (b) of the figure shows the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. Here, the line L114c represents the cathode potential Vc during low-temperature activation, and the line L116c represents the cathode potential Vc during high-temperature activation. In addition, the line L114d represents the cathode potential Vc during the operation after low-temperature activation, and the line L116d represents the cathode potential Vc during the operation after high-temperature activation.

[0152] (c) of the figure shows the anode potential of the photodiode 252. The vertical axis represents the anode potential, and the horizontal axis represents time. Here, the line L118c represents the anode potential during low-temperature activation, and the line L120c represents the anode potential during high-temperature activation. In addition, the line L118d represents the anode potential during the operation after low-temperature activation, and the line L120d represents the anode potential during the operation after high-temperature activation.

[0153] (d) of the figure shows the anode current of the photodiode 252. The vertical axis represents the anode current, and the horizontal axis represents time. Here, the line L122c represents the anode current during low-temperature activation, and the line L124c represents the anode current during high-temperature activation. In addition, the line L122d represents the anode current during the operation after low-temperature activation, and the line L124d represents the anode current during the operation after high-temperature activation.

[0154] The operation state of (a) of the figure will be described. First, the photodetection element 200 is based on the control unit 120 ( Figure 1) control starts to drive. At this time, the anode potential supply power source 220 also starts to drive, and the anode potential supply power source 220 controls the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to a predetermined fixed potential (time t10a).

[0155] Next, in synchronization with the light emission of the light emitting unit 110, the generation of the photocurrent of the photodiode 252 is awaited (time t16a), and the cathode potential Vc after a predetermined time when the cathode potential Vc exceeds the threshold th (see Figure 5 ) is acquired as the bottom potential Vbtm by the VBD monitoring circuit 270 (time t18a). The control circuit 210 supplies the control value obtained by adding the adjustment value delta (see Expression (3)) to the bottom potential Vbtm to the anode potential supply power source 220, and the anode potential supply power source 220 controls the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to the control value (step S20a). Thereafter, the timings t16a to t20a are repeated until imaging ends.

[0156] As shown in (c) of the figure, by voltage control at timing t10a, the anode potential is controlled to the same anode potentials L118c and L120c in both the case of low-temperature activation and the case of high-temperature activation. Therefore, as shown in (b) of the figure, the cathode potential line L114c can exceed the target potential Vtarge in the case of low-temperature activation. Accordingly, the voltage VEX between the anode and the cathode of the photodiode 252 increases beyond the target voltage.

[0157] On the other hand, as shown in (b) of the figure, in the case of high-temperature activation, the cathode potential line L116c can be in a state where it does not reach the target potential Vtarge. Accordingly, the voltage VEX between the anode and the cathode of the photodiode 252 decreases beyond the target voltage. Therefore, as Figure 5 shown, an error occurs in the distance measurement.

[0158] In addition, as shown in (d) of the figure, the anode currents I122c and L124c at this time vary between the case of low-temperature activation and the case of high-temperature activation.

[0159] Similarly, during operation, as shown in (c) of the figure, by controlling the voltage at time t20a, the anode potential is controlled to a higher anode potential L118d during low-temperature activation, and the anode potential is controlled to a lower anode potential L120d during low-temperature activation. Therefore, as shown in (b) of the figure, during low-temperature activation and during the operation after high-temperature activation, the potential near the target potential Vtarget of the cathode potential lines L114d and L116d also becomes the bottom potential Vbtm. In addition, as shown in (d) of the figure, the anode currents L122d and L124d at this time also have the same values during low-temperature activation and during the operation after high-temperature activation, and the error in distance measurement is suppressed. As described above, when the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 is controlled to a predetermined fixed potential during activation, due to the influence of the temperature characteristics of the photodiode 252, the measurement error during activation increases.

[0160] On the other hand, in the control circuit 210 according to the present application, as described above, the temperature monitoring circuit 280 acquires the temperature monitoring value, and the anode potential absolute value calculation unit 301 calculates the anode potential abs (see Expression (2)). Then, since the control circuit 210 controls the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to the anode potential abs, the influence of the temperature characteristics of the photodiode 252 can be suppressed, and the measurement error during activation can be suppressed.

[0161] Here, the configuration of the VBD monitoring circuit 270 will be described with reference to Figure 11 in more detail. Figure 11 FIG. is a circuit diagram showing a configuration example of the monitoring pixel circuit 260 and the VBD monitoring circuit 270. The monitoring pixel circuit 260 includes the resistor 251 and the photodiode 252 as described above. In addition, the VBD monitoring circuit 270 includes an inverter 271, an adjustment circuit 272, a transistor 273, a plurality of buffers 274 and 277, a switching element 275, and a capacitor 276.

[0162] The inverter 271 of the VBD monitoring circuit 270 inverts the signal of the cathode potential Vc of the photodiode 252 and outputs the inverted signal as a pulse signal OUT to the adjustment circuit 272. The inverter 271 outputs a low-level pulse signal OUT when the cathode potential Vc is higher than a predetermined value, and outputs a high-level pulse signal OUT when the cathode potential is equal to or lower than the predetermined value. The adjustment circuit 272 adjusts the delay time and the high-level width of the high-level pulse signal OUT output from the inverter 271.

[0163] As the transistor 273, for example, an N-type metal oxide semiconductor (MOS) transistor is used. A gate signal GAT for applying a predetermined potential is applied to the gate of the transistor 273. Its source is connected to the back gate and the ground terminal, and its drain is connected to the cathode of the photodiode 252, the input terminal of the inverter 271, and the input terminal of the buffer 274. For example, a low level is set for the gate signal during the row read cycle.

[0164] The output terminal of the buffer 274 is connected to one end of the switching element 275. In addition, the other end of the switching element 275 is connected to the input terminal of the buffer 277 and one end of the capacitor 276. The switching element 275 is, for example, an N-type metal oxide semiconductor (MOS) transistor, and enters a connected state when the output signal of the adjustment circuit 272 is at a high level, and enters a non-connected state when the output signal is at a low level.

[0165] The other end of the electrostatic capacitor 276 is connected to the ground potential. When the switching element 275 is in the connected state, the capacitor 276 samples the cathode potential Vc. As Figure 8 shown, since the bottom potential Vbtm according to the present embodiment is controlled to the target potential Vtarget, the adjustment circuit 272 can monitor the bottom potential Vbtm of the cathode potential Vc by adjusting the delay time and the high level width of the high level pulse signal OUT applied to the switching element 275. That is, the capacitor 276 samples the bottom potential Vbtm.

[0166] The output terminal of the buffer 277 is connected to the anode potential adjustment amount calculation unit 302 of the arithmetic circuit 300 (see Figure 3 ). The buffer 277 outputs the sampled value of the bottom potential Vbtm to the anode potential adjustment amount calculation unit 302.

[0167] Figure 12 is a diagram showing an example of the operation characteristics of the VBD monitoring circuit 270. (a) is a diagram showing the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. The line L130 represents the time change of the cathode potential Vc. (b) of the figure is a diagram showing the output signal of the adjustment circuit 272. The vertical axis represents the signal level, and the horizontal axis represents time. (c) of the figure is a diagram showing the sampled potential of the capacitor 276. The vertical axis represents the bottom potential Vbtm, and the horizontal axis represents time. In addition, the potential range of the capacitor 276 that can be sampled is indicated as the output dynamic range Wd. The line L134 indicates the time change of the bottom potential Vbtm. (d) of the figure is a diagram showing the anode current of the photodiode 252. The vertical axis represents the anode current, and the horizontal axis represents time. The line L136 represents the time change of the anode current.

[0168] As shown by line L130 in Fig. (a), when the control circuit 210 performs control, the bottom potential Vbtm of the cathode potential Vc approaches the target potential Vtarget. At this time, the voltage VEX between the cathode and anode of the photodiode 252 is the target value.

[0169] As shown by line L132 in Fig. (b), when the cathode potential Vc is higher than a predetermined threshold, the inverter 271 outputs a low-level pulse signal OUT. Then, the adjustment circuit 272 delays the pulse signal OUT by a predetermined time delay and shapes the pulse signal OUT into a predetermined pulse width. The time delay and pulse width are set at the position of the bottom potential Vbtm of the cathode potential Vc. Therefore, as shown by line L134 in Fig. (c), the capacitor 276 samples the bottom potential Vbtm of the cathode potential Vc and outputs the bottom potential Vbtm. In addition, as shown by line L136 in Fig. (d), the anode current also has a peak at the target time relative to the threshold Vth.

[0170] Figure 13 It is a diagram showing an example of the operating characteristics of the VBD monitoring circuit 270 without using the temperature monitoring value at high temperature. Figs. (a) to (d) are diagrams corresponding to Figure 12 the diagrams. (a) is a diagram showing the cathode potential Vc of the photodiode 252. Line L130a indicates the time change of the cathode potential Vc when activated at a temperature where the temperature monitoring value is not used as an activation. Fig. (b) is a diagram showing the output signal of the adjustment circuit 272. The vertical axis represents the signal level, and the horizontal axis represents time. Fig. (c) is a diagram showing the sampling potential of the capacitor 276. The vertical axis represents the bottom potential Vbtm, and the horizontal axis represents time. Line L134a indicates the time change of the bottom potential Vbtm. Fig. (d) is a diagram showing the anode current of the photodiode 252. Line L136a represents the time change of the anode current.

[0171] As shown by line L130a in Fig. (a), when the control circuit 210 performs control without using the temperature monitoring value, the bottom potential Vbtm of the cathode potential Vc becomes a high potential and in some cases does not exceed the threshold potential Vth. In this case, as shown in Fig. (b), since the inverter 271 always outputs a low-level pulse signal OUT, the adjustment circuit 272 cannot generate a high-level signal. Therefore, the capacitor 276 cannot sample the bottom potential Vbtm of the cathode potential Vc and maintains the initial value. In addition, as shown by line L136a in Fig. (d), the anode current also further decreases. As described above, when the temperature monitoring value is not used at high temperature, the bottom potential Vbtm of the cathode potential Vc cannot be sampled, and the control in the control circuit 210 during operation is not performed.

[0172] Figure 14 is a diagram showing the time variation of the cathode potential Vc without using the temperature monitoring value at high temperature. The vertical axis represents the cathode potential Vc of the photodiode 252, and the horizontal axis represents time. The line L1300a indicates the time variation of the cathode potential Vc at activation when the control circuit 210 performs control without using the temperature monitoring value. As Figure 13 shown, when the bottom potential Vbtm of the cathode potential Vc becomes a high potential and does not exceed the threshold potential Vth, control during the operation in the control circuit 210 becomes impossible, and the state where the cathode potential Vc does not exceed the threshold potential Vth continues. As described above, when the control circuit 210 does not perform control when driving using the temperature monitoring value, control during the operation becomes impossible, and the error in distance measurement continues to increase.

[0173] On the other hand, since the control circuit 210 according to the present application controls the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to the anode potential abs at the time of driving as described above (see Expression (2)), the influence of the temperature characteristics of the photodiode 252 on the temperature characteristics can be suppressed, and the measurement error can be suppressed at activation.

[0174] Figure 15 is a diagram showing an example of the operation characteristics of the VBD monitoring circuit 270 without using the temperature monitoring value at low temperature. (a) to (d) of the figure are diagrams corresponding to Figure 12 . (a) is a diagram showing the cathode potential Vc of the photodiode 252. The line L130b indicates the time variation of the cathode potential Vc at activation when the temperature monitoring value is not used as the temperature at activation. (b) of the figure is a diagram showing the output signal of the adjustment circuit 272. The vertical axis represents the signal level, and the horizontal axis represents time. The line L132b represents the time variation of the output signal of the adjustment circuit 272. (c) of the figure is a diagram showing the sampling potential of the capacitor 276. The vertical axis represents the bottom potential Vbtm, and the horizontal axis represents time. The line L134b indicates the time variation of the bottom potential Vbtm. (d) of the figure is a diagram showing the anode current of the photodiode 252. The line L136b represents the time variation of the anode current.

[0175] As shown by line L130b in (a) of the figure, without the control circuit 210 performing control, the bottom potential Vbtm of the cathode potential Vc becomes a low potential and can become less than the target potential Vtarget. In this case, as shown in (b) of the figure, the adjustment circuit 272 generates a high-level signal. However, as shown in (c) of the figure, since the bottom potential Vbtm indicated by line L134c exceeds the potential within the range where the capacitor 276 can sample, the capacitor 276 cannot sample the bottom potential VbtmL134c of the cathode potential Vc, and samples the value of L134b as an incorrect value. In addition, as shown by line L136b in (d) of the figure, the anode current also increases.

[0176] Figure 16 is a diagram showing the time change of the cathode potential Vc without using the temperature monitoring value at low temperature. The vertical axis represents the cathode potential Vc of the photodiode 252, and the horizontal axis represents time. Line L1300b represents the time change of the cathode potential Vc when activated without the control circuit 210 performing control using the temperature monitoring value. As Figure 15 shown, when the bottom potential Vbtm of the cathode potential Vc becomes a low potential and becomes less than the target potential Vtarget, the anode potential is controlled by the bottom potential Vbtm with an erroneously sampled value. Therefore, it takes time to converge to the target potential Vtarget. As a result, the current consumption increases, and the distance measurement error increases.

[0177] On the other hand, since the control circuit 210 according to the present application controls the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to the anode potential abs during driving as described above (see Expression (2)), the influence of the temperature characteristics of the photodiode 252 can be suppressed, and the measurement error can be suppressed during activation.

[0178] Figure 17 is a flowchart showing an operation example of the light detection element 200 of the present embodiment. As Figure 17 shown, first, the light detection element 200 starts driving according to the control of the control unit 120 ( Figure 1 ) (step S100). Subsequently, the anode potential absolute value calculation unit 301 reads the coefficient α from the storage unit 290 (step S102). Subsequently, the temperature monitoring circuit 280 acquires the temperature T and supplies the temperature T to the anode potential absolute value calculation unit 301 (step S104).

[0179] Next, the anode potential absolute value calculation unit 301 calculates the anode potential abs (see Expression (2)) (step S106). Subsequently, the control circuit 210 supplies the anode potential abs to the anode potential supply power source 220, and the anode potential supply power source 220 controls the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to the anode potential abs (step S108). Subsequently, measurement at activation is started synchronously with the light emission of the light emitting unit 110 (step S110).

[0180] Next, the VBD monitoring circuit 270 waits for the generation of the photocurrent of the photodiode 252, and acquires the cathode potential Vc as the bottom potential Vbtm after a predetermined time when the cathode potential Vc exceeds the threshold th (see Figure 5 ). Subsequently, the anode potential adjustment amount calculation unit 302 calculates the adjustment value delta (see Expression (3)) (step S114).

[0181] Next, the control circuit 210 supplies the control value obtained by adding the adjustment value delta (see Expression (3)) to the bottom potential Vbtm to the anode potential supply power source 220. The anode potential supply power source 220 adjusts the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to the control value, and performs measurement at activation synchronously with the light emission of the light emitting unit 110 (step S116). The control unit 120 determines whether to continue the process (step S118), and when continuing (Yes in step S112), repeats the process starting from step S118. On the other hand, when the process ends (No in step S118), the control unit 120 ends the entire process.

[0182] As described above, according to the present embodiment, the control circuit 210 controls the anode potential of the photodiode 252 according to the temperature T of the photodiode 252 at activation. Therefore, temperature fluctuations of the anode potential in the photodiode 252 can be suppressed, and the bottom potential Vbtm of the photodiode 252 can be controlled to a predetermined target potential Vtarget. In addition, the anode-cathode voltage VEX at breakdown becomes constant regardless of temperature, and a decrease in distance measurement accuracy is suppressed.

[0183] (First Modification of the First Embodiment)

[0184] The distance measurement module 100 according to the first modification of the first embodiment is different from the distance measurement module 100 according to the first embodiment in that the arithmetic circuit 300a also has the circuit configuration of the control circuit 210. Hereinafter, the differences from the distance measurement module 100 according to the first embodiment will be described below.

[0185] Figure 18 is a diagram showing a configuration example of a pixel array unit 240a and an arithmetic circuit 300a according to a first modification of the first embodiment. In Figure 18 , the description of the signal processing unit 230 is omitted. In addition, the imaging pixel circuit 250 shows a part of the circuit structure. As Figure 18 shown, the distance measurement module according to the first embodiment is different from the distance measurement module 100 according to the first embodiment in that the arithmetic circuit 300a also has a circuit configuration of the control circuit 210 (see Figure 8 ). According to this structure, by integrating the circuit structure of the control circuit 210 and the circuit structure of the arithmetic circuit 300a into the same element, further miniaturization of the light detection element 200a can be achieved.

[0186] (Second modification of the first embodiment)

[0187] The distance measurement module 100 according to the second modification of the first embodiment is different from the distance measurement module 100 according to the first embodiment in that the arithmetic circuit 300a also has a circuit configuration of the control circuit 210, and the pixel array unit 240b is separated from the arithmetic circuit 300b. Hereinafter, the differences from the distance measurement module 100 according to the first embodiment will be described.

[0188] Figure 19 is a diagram showing a configuration example of a pixel array unit 240b and an arithmetic circuit 300b according to a second modification of the first embodiment. In Figure 19 , the description of the signal processing unit 230 is omitted. In addition, the imaging pixel circuit 250 shows a part of the circuit structure. As Figure 19 shown, the difference from the distance measurement module 100 according to the first embodiment is that the arithmetic circuit 300b also has a circuit configuration of the control circuit 210, and the pixel array unit 240b is separated from the arithmetic circuit 300b. With this configuration, the pixel array unit 240b can include an imaging pixel circuit 250, a monitoring pixel circuit 260, a VBD monitoring circuit 270, a temperature monitoring circuit 280, and a storage unit (memory) 290, so that the versatility of the pixel array unit 240b is further improved.

[0189] (Second embodiment)

[0190] The distance measurement module 100 according to the second embodiment is different from the distance measurement module 100 according to the first embodiment in that the arithmetic circuit 300c further includes a VBD time variation calculation unit 303 for correcting the breakdown voltage VBD(T) (see Figure 6 ). Hereinafter, the differences from the distance measurement module 100 according to the first embodiment will be described.

[0191] Figure 20 is a block diagram showing a configuration example of the pixel array unit 240c according to the second embodiment. As Figure 20 shown, the arithmetic circuit 300c further includes a VBD time change amount calculation unit 303.

[0192] Figure 21 is a diagram showing the time changes of the cathode potential Vc and the anode potential Va of the photodiode 252. (a) is a diagram showing the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. The line L150 represents the time change of the cathode potential before the correction breakdown voltage VBD(T). In addition, the line L152 indicates the time change of the cathode potential V when the cathode potential V coincides with the target potential Vtarget at activation. In addition, the line L154 represents the time change of the cathode potential after the correction breakdown voltage VBD(T).

[0193] (b) is a diagram showing the anode potential of the photodiode 252. The vertical axis represents the m-anode potential Va, and the horizontal axis represents time. The line L156 represents the time change of the anode potential Va before the correction breakdown voltage VBD(T), and the line L158 represents the time change of the anode potential Va after the correction breakdown voltage VBD(T).

[0194] As shown in (a) of the figure, when the breakdown voltage VBD(T) is accurate, the time change of the cathode potential Vc becomes the line L152. However, for example, due to long-term changes, the breakdown voltage VBD(T) may deviate. Therefore, as in the line L150, a deviation occurs at the bottom potential Vbtm. As described above, the bottom potential Vbtm of the line L150 is monitored as the bottom potential Vbtm of the VBD monitoring circuit 270. At this time, the adjustment value delta calculated by the anode potential adjustment amount calculation unit 302 is the value shown in Expression (3).

[0195] As can be seen from these, the calculated adjustment value delta becomes the potential generated by the deviation of the breakdown voltage VBD(T) after activation. In addition, the temperature at this time is set to T0, and the initial adjustment value delta is set to the VBD time change amount ΔVBD(T0). The VBD time change amount calculation unit 303 stores the initial adjustment value delta in the storage unit 290 as the VBD time change amount ΔVBD(T0).

[0196] Figure 22 is a diagram showing an example of the temperature characteristics of the cathode potential Vc. The vertical axis represents the breakdown voltage VBD(T), and the horizontal axis represents temperature. The temperature characteristic line L160 after the time change of the breakdown voltage VBD(T) and the temperature characteristic line L162 before the time change of the breakdown voltage VBD(T) are shown. AsFigure 22 As shown, the change in the individual value temperature coefficient α representing the slope of the temperature characteristic line L160 is minute. Therefore, the anode potential absolute value calculation unit 301 adjusts the intercept value by adding the VBD time change amount ΔVBD(T0), as shown in Expression (4), so that the temperature characteristic line L160 after the time change coincides with the temperature characteristic line L162 before the time change.

[0197] [Expression 4]

[0198] VBDa(T) = VBD(T0) + α*{T - T0} + ΔVBD(T0) (4)

[0199] [Expression 5]

[0200] abs = (VE - Vtarget) - VBDa(T) + c (5)

[0201] The anode potential absolute value calculation unit 301 substitutes VBDa(T) in Expression (4) into Expression (1) to calculate the corrected anode potential abs in Expression (5).

[0202] As Figure 21 shown, when the anode potential is controlled with the anode potential abs in Expression (5), as shown by line L154, the bottom potential Vbtm matches the target potential Vtarget. The adjustment value delt at this time is 0.

[0203] Figure 23 is a flowchart showing an operation example of the photodetection element 200 of the second embodiment. The same processes as those in the flowchart shown in Figure 17 are denoted by the same reference numerals, and their descriptions are omitted. The processes of steps S101 to S104 end. Next, the anode potential absolute value calculation unit 301 substitutes VBDa(T) in Expression (4) into Expression (1) to calculate the corrected anode potential abs in Expression (5) (step S106a). Then, the control circuit 210 supplies the corrected anode potential abs in Expression (5) to the anode potential supply power source 220, and the anode potential supply power source 220 controls the potential of the anode of the photodiode 252 in the imaging pixel circuit 250 and the monitoring pixel circuit 260 to the corrected anode potential abs (step S108).

[0204] Subsequently, after the processing of steps S112 to S114 is completed, the VBD time variation calculation unit 303 determines whether it is the first control after driving (step S120). In the case where it is determined that the control is the first control after driving (Yes in step S120), the VBD time variation calculation unit 303 stores the adjustment value delta calculated by the anode voltage adjustment amount calculation unit 302 (see Expression (3)) as the VBD time variation ΔVBD(T0) in the storage unit 190.

[0205] On the other hand, in the case where it is determined that it is not the first control (No in step S120), the VBD time variation calculation unit 303 performs the processing starting from S116.

[0206] As described above, according to the present embodiment, the VBD time variation calculation unit 303 stores the adjustment value delta in the first control (see Expression (3)) as the VBD time variation ΔVBD(T0) in the storage unit 190. Then, the control circuit 210 controls the anode potential of the photodiode 252 when starting driving with the corrected anode potential abs in Expression (5) including the VBD time variation ΔVBD(T0). Therefore, the deviation between the bottom potential Vbtm and the target potential Vtarget due to the time variation of the photodiode 252 can be suppressed.

[0207] (First modification of the second embodiment)

[0208] The distance measurement module 100 according to the first modification of the second embodiment is different from the distance measurement module 100 according to the second embodiment in that the control circuit 210d includes the VBD time variation calculation unit 303. Hereinafter, the differences from the distance measurement module 100 according to the first embodiment will be described below.

[0209] Figure 24 is a diagram showing a configuration example of the imaging element 200 according to the second embodiment. As Figure 24 shown, the control circuit 210d is different from the distance measurement module 100 according to the second embodiment in that it includes a second storage unit 292, a first adder circuit 213a, a second adder circuit 213b, and the VBD time variation calculation unit 303. The second storage unit 292 stores the VBD time variation ΔVBD(T0).

[0210] [Expression 6]

[0211] abs2 = abs - ΔVBD(T0) (6)

[0212] As shown in Expression (6), the first adder circuit 213a adds the VBD time variation ΔVBD(T0) of the second storage unit 292 to the anode potential abs shown in Expression (3) to calculate the anode potential abs2. The selection circuit 211 outputs the anode potential abs2 as a control value when activated.

[0213] On the other hand, the second adder circuit 213b adds the adjustment potential δ to the previous anode potential held in the holding circuit 212. During operation, the selection circuit 211 outputs the output value of the second adder circuit 213b as a control value.

[0214] As described above, according to the present embodiment, the VBD time variation calculation unit 303 is arranged in the control circuit 210d. Therefore, in addition to the effects of the ranging module 100 according to the first embodiment, it is also possible to suppress the deviation between the bottom potential Vbtm and the target potential Vtarget caused by the time variation of the photodiode 252.

[0215] (Third Embodiment)

[0216] The ranging module 100 according to the third embodiment is different from the ranging module 100 according to the second embodiment in that it includes a VBD time variation calculation unit 303a having a temperature change threshold determination. Hereinafter, the differences from the ranging module 100 according to the second embodiment will be described.

[0217] Figure 25 is a block diagram showing a configuration example of the pixel array unit 240e according to the third embodiment. As Figure 25 shown, the arithmetic circuit 300e includes a VBD time variation calculation unit 303a having a temperature change threshold determination.

[0218] Figure 26 is a diagram showing the time variations of the cathode potential Vc, the anode potential Va, and the temperature T of the photodiode 252. (a) is a diagram showing the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. The line L160 represents the time variation of the cathode potential Vc before the correction breakdown voltage VBD(T). In addition, the line L162 indicates the time variation of the cathode potential Vc when the bottom potential Vbtm coincides with the target potential Vtarget at activation.

[0219] (b) is a diagram showing the anode potential of the photodiode 252. The vertical axis represents the anode potential Va, and the horizontal axis represents time. The line L164 represents the time variation of the anode potential Va before correcting the breakdown voltage VBD(T). (c) of the figure is a diagram showing the temperature of the photodiode 252. The vertical axis represents the temperature T, and the horizontal axis represents time. The line L166 represents the time variation of the temperature T of the photodiode 252.

[0220] As shown in Expressions (4) and (5), the VBD time variation amount calculation unit 303a with temperature change threshold determination can set the adjustment value delta in the first control (see Expression (3)) to the VBD time variation amount ΔVBD(T0). On the other hand, as shown in (c) of the figure, sometimes a temperature change AT occurs between startup and the first control. At this time, the component α×ΔT of the VBD fluctuation caused by the temperature change is added to the VBD time variation amount ΔVBD(T0).

[0221] Figure 27 is a diagram showing an operation example of the photodiode 252 when driving using the VBD time variation amount ΔVBD(T0) in the case of a temperature change ΔT occurring. (a) is a diagram showing the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. The line L168 represents the time variation of the corrected cathode potential Vc. In addition, the line L162 indicates the time variation of the cathode potential when the bottom potential Vbtm coincides with the target potential Vtarget at activation.

[0222] (b) of the figure is a diagram showing the anode potential Va of the photodiode 252. The vertical axis represents the anode potential Va, and the horizontal axis represents time. The line L170 indicates the time variation of the anode potential Va after correcting the individual value temperature coefficient α. (c) of the figure is a diagram showing the temperature of the photodiode 252. The vertical axis represents the temperature, and the horizontal axis represents time. The line L172 indicates the time variation of the temperature of the photodiode 252.

[0223] As shown in (c) of the figure, the temperature change of the line L172 is different from the temperature change of the line L166. Therefore, as shown by the line L168 in (a) of the figure, in the case of a temperature change ΔT occurring, the cathode potential after correcting the breakdown voltage VBD(T) using the VBD time variation amount ΔVBD(T0) deviates from the target potential Vtarget. Therefore, the VBD time variation amount calculation unit 303a with temperature change threshold determination according to the present embodiment calculates the temperature change ΔT of a predetermined time width of the temperature monitoring value of the temperature monitoring circuit 280, and executes control not to update the VBD time variation amount ΔVBD when the temperature change ΔT exceeds the threshold.

[0224] More specifically, the VBD time variation calculation unit 303a with temperature change threshold determination calculates the difference ΔT = (T1 - T0) between the activation temperature T0 and the temperature T1 at the time of the first increment calculation during operation. Then, when the temperature difference ΔT is equal to or less than the temperature change threshold ΔTth, the VBD time variation calculation unit 303a with temperature change threshold determination updates the VBD time variation ΔVBD according to Expression (7) using the first increment during operation and the VBD time variation ΔVBD read from the storage unit 290.

[0225] [Expression 7]

[0226] ΔVBD (updated value) = ΔVBD (value read from memory) - Δ (first operation) (7)

[0227] On the other hand, when the temperature difference AT is equal to or greater than the temperature change threshold ΔTth, the VBD time variation ΔVBD is not updated. By obtaining the VBD time variation only when the temperature change is small, the bottom potential Vbtm can be accurately adjusted from the activation time.

[0228] (First modification of the third embodiment)

[0229] The ranging module 100 according to the first modification of the third embodiment is different from the ranging module 100 according to the third embodiment in that the control circuit 210f includes a VBD time variation calculation unit 303a with temperature change threshold determination. Hereinafter, the differences from the ranging module 100 according to the third embodiment will be described.

[0230] Figure 28 is a diagram showing a configuration example of the imaging element 200 according to the second embodiment. As Figure 28 shown, the control circuit 210f is different from the ranging module 100 according to the third embodiment in that it includes a second storage unit 292 with temperature change threshold determination, a first adder circuit 213a, a second adder circuit 213b, and a VBD time variation calculation unit 303a. As described above, the second storage unit 292 stores the VBD time variation ΔVBD(T0).

[0231] As shown in the above Expression (6), the first adder circuit 213a adds the VBD time variation ΔVBD(T0) of the second storage unit 292 to the anode potential abs shown in Expression (3) to calculate the anode potential abs2. The selection circuit 211 outputs the anode potential abs2 as a control value at activation.

[0232] On the other hand, the second adder circuit 213b adds the adjustment potential δ to the previous anode potential held in the holding circuit 212. During operation, the selection circuit 211 outputs the output value of the second adder circuit 213b as the control value.

[0233] As described above, according to the present embodiment, the VBD time change amount calculation unit 303a having temperature change threshold determination is configured in the control circuit 210f. Therefore, in addition to the effects of the distance measurement module 100 according to the first embodiment, it is possible to suppress the deviation between the bottom potential Vbtm and the target potential Vtarget caused by the time change of the photodiode 252, and to accurately adjust the bottom potential Vbtm from activation by obtaining the VBD time change amount only when the temperature change is small.

[0234] (Fourth Embodiment)

[0235] The distance measurement module 100 according to the fourth embodiment is different from the distance measurement module 100 according to the first embodiment in that, when the photodiode 252 of the monitoring pixel circuit 260 cannot generate a photocurrent that reaches the accuracy that the VBD monitoring circuit 270 can maintain, the information of the temperature monitoring circuit 280 can be used to control the anode potential Va. Hereinafter, the differences from the distance measurement module 100 according to the first embodiment will be described.

[0236] Figure 29 FIG. is a block diagram showing a configuration example of the distance measurement module 100 according to the fourth embodiment of the present technology. The distance measurement module 100 is mounted on the electronic device 1. The electronic device I is a smart phone. FIG. (a) is a diagram schematically showing a plan view of the smart phone. FIG. (b) is a diagram schematically showing a cross-sectional view of the distance measurement module 100.

[0237] As shown in FIG. (b), the distance measurement module 100 includes optical systems 130 and 140. The light emitting unit 110 emits measurement light via the optical system 130. The light detection element 200 receives the return light from the object via the optical system 140. However, the photodiode 252 of the monitoring pixel circuit 260 may not be able to generate a photocurrent. For example, the return light does not hit the photodiode 252 of the monitoring pixel circuit 260, or the ambient light is insufficient, such as at night. In this case, the anode potential Va cannot be appropriately controlled.

[0238] In this case, as Figure 6 shown, the breakdown voltage VBD(T) varies according to the temperature. Therefore, as Figure 10 shown, the anode-cathode voltage VEX fluctuates.

[0239] Figure 30It is a diagram showing the relationship between the anode-cathode voltage VEX and the pixel sensitivity of the imaging pixel circuit 250. The vertical axis represents the sensitivity, and the horizontal axis represents the anode-cathode voltage VEX. As shown by the change curve L190 of the pixel sensitivity, as the anode-cathode voltage VEX decreases, the pixel sensitivity decreases.

[0240] Figure 31 It is a diagram showing the relationship between the anode-cathode voltage VEX and the distance error of the imaging pixel circuit 250. The vertical axis represents the distance error, and the horizontal axis represents the anode-cathode voltage VEX. As shown by the change curve L192 of the distance error, the distance error increases as the anode-cathode voltage VEX decreases. As described above, when the anode-cathode voltage VEX is not controlled within an appropriate range, the distance error of the imaging pixel circuit 250 increases.

[0241] Figure 32 It is a cross-sectional view showing a configuration example of the light detection element 200k according to the fourth embodiment. As Figure 32 shown, the VBD monitoring circuit 270k generates Flag 1 when generating a photocurrent within the measurable range of the photodiode 252 of the monitoring pixel circuit 260. On the other hand, a flag 0 is generated during activation and when the photodiode 252 does not generate a photocurrent within the measurable range. The monitoring pixel circuit 260 outputs the flag to the selection unit 305 of the arithmetic circuit 300g.

[0242] The VBD monitoring circuit 270g generates Flag1, for example, when the cathode potential Vc exceeds Figure 7 the threshold potential Vth shown, etc. On the other hand, when the cathode potential does not exceed the threshold potential, a flag 0 is generated.

[0243] The arithmetic circuit 300g includes a first anode voltage adjustment amount calculation unit 304a, a second anode voltage adjustment amount calculation unit 304b, and a selection unit 304. The first anode voltage adjustment amount calculation unit 304a can perform the same operation as the anode potential absolute value calculation unit 301 (see Figure 3 ) during activation. Therefore, during activation, the anode potential abs is calculated according to Expressions (1) and (2).

[0244] [Expression 8]

[0245] delta = -α × (T1a - T1b) (8)

[0246] In addition, the first anode voltage adjustment amount calculation unit 304a obtains the temperature T1 from the temperature monitoring circuit 280 during calculation and causes the storage unit 290 to hold the temperature T1. That is, even during operation, when the flag is 0, the first anode voltage adjustment amount calculation unit 304a calculates the adjustment value delta of the anode potential according to Expression (8).

[0247] The temperature T1b is the temperature during the previous operation, and T1a is the temperature during the current operation. As Figure 6 shown, since the breakdown voltage VBD(T) has a slope with a coefficient α depending on the temperature and changes substantially linearly, the temperature fluctuation of the bottom potential Vbtm depending on the breakdown voltage VBD(T) can be suppressed by using the temperature difference (T1a - T1b). Therefore, if the bottom potential Vbtm has a value equal to the target potential Vtarget at the temperature T1b, the bottom potential Vbtm also has a value equal to the target potential Vtarget at the temperature T1a.

[0248] The second anode voltage adjustment amount calculation unit 304b has the same configuration as the anode voltage adjustment amount calculation unit 302 (see Figure 3 ). That is, the second anode voltage adjustment amount calculation unit 304b calculates the adjustment value delta according to Expression (3) when the flag is set to 1.

[0249] The selection unit 305 outputs the adjustment value delta generated by the first anode voltage adjustment amount calculation unit 304a when the flag is 0, and outputs the adjustment value delta generated by the second anode voltage adjustment amount calculation unit 304b when the flag is 1.

[0250] The control circuit 210g includes a holding circuit 212g and an addition circuit 213g. The holding circuit 212g holds and updates the output value of the addition circuit 213g. At activation, the holding circuit 212g is reset to 0. Therefore, at activation, the anode potential abs in Expression (2) is stored. From the second time, the addition circuit 213g adds the adjustment value delta to the value held by the holding circuit 212g. That is, the anode potential abs is sequentially adjusted by the adjustment value delta.

[0251] Figure 33 A diagram showing an example of performing control in the case where all flags are set to 1 except during the activation time. (a) of the figure is a schematic diagram showing the change L200 of the ambient light amount. The vertical axis represents the ambient light amount, and the horizontal axis represents time.

[0252] Part (b) of the figure is a diagram showing the change L202 in the temperature T obtained from the temperature monitoring circuit 280. The vertical axis represents the temperature T, and the horizontal axis represents time. Part (c) of this figure is a diagram showing the change L204 in the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. Part (d) of the figure is a diagram showing the change L206 in the anode potential Va of the photodiode 252. The vertical axis represents the anode potential Va, and the horizontal axis represents time.

[0253] From these figures, it can be seen that the VBD monitoring circuit 270 operates in a bright environment, and the bottom potential Vbtm of the cathode potential Vc is approximately the same as the target potential Vtarget. On the other hand, the VBD monitoring circuit 270 does not operate in a dark environment, the anode potential becomes a constant value, and the bottom potential Vbtm rises according to temperature fluctuations.

[0254] Figure 34 A diagram showing an example of performing control using the temperature T when the flag is set to 0 in the case where the VBD monitoring circuit 270 does not operate. Part (a) of the figure is a schematic diagram showing the change L200 in the ambient light amount. The vertical axis represents the ambient light amount, and the horizontal axis represents time.

[0255] Part (b) of the figure is a diagram showing the change L202 in the temperature T obtained from the temperature monitoring circuit 280. The vertical axis represents the temperature T, and the horizontal axis represents time. Part (c) of this figure is a diagram showing the change L208 in the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. Part (d) of the figure is a diagram explaining the variation L210 in the anode potential Va of the photodiode 252. The vertical axis represents the anode potential Va, and the horizontal axis represents time.

[0256] In Figure 34 even when the VBD monitoring circuit 270 does not operate in a dark environment, control using the temperature according to Expression (7) is performed. Therefore, the anode potential is controlled to an appropriate value, and even when temperature fluctuations occur, the bottom potential Vbtm becomes a value equal to the target potential Vtarget. As described above, even when the VBD monitoring circuit 270 does not operate, by controlling using the temperature according to Expression (7), even when the temperature T fluctuates, the anode-cathode voltage VEX can be maintained at an appropriate value, and a decrease in measurement accuracy can be suppressed. In this way, a decrease in sensitivity and a distance deviation are suppressed.

[0257] Figure 35FIG. is a diagram showing a configuration example of the VBD monitoring circuit 270g according to the fourth embodiment. The VBD monitoring circuit is different from the VBD monitoring circuit 270 according to the first embodiment in that the output of the inverter 271 is output as a detection flag. As described above, the inverter 271 outputs a high-level 1 when the cathode potential Vc exceeds the threshold potential Vth, and outputs a low-level 0 when the cathode potential Vc does not exceed the threshold potential Vth. Therefore, it is possible to determine whether the VBD monitoring circuit 270g is operating.

[0258] Figure 36 FIG. is a flowchart showing an example of control processing during the measurement operation in the present embodiment. The same processing as in Figure 17 is denoted by the same reference numerals, and its description is omitted. When the measurement operation is turned on, the VBD monitoring circuit 270 outputs a detection flag. When the detection flag is I (Yes in step S111), the second anode voltage adjustment amount calculation unit 304b acquires the bottom potential Vbtm monitored by the BVBD monitoring circuit 270 when the flag is I (step S112), and the second anode voltage adjustment amount calculation unit 304b calculates the adjustment value delta according to Expression (3).

[0259] On the other hand, when the detection flag is 0 (No in step S111), the first anode voltage adjustment amount calculation unit 304a acquires the temperature T1 from the temperature monitoring circuit 280 (step S104). Then, the first anode voltage adjustment amount calculation unit 304a calculates the adjustment value delta of the anode potential according to Expression (7) (step S106a).

[0260] As described above, when the VBD monitoring circuit 270 cannot maintain accuracy, the distance measurement module 100 according to the present embodiment controls the anode potential Va using the temperature T of the temperature monitoring circuit 280. Therefore, even when the photodiode 252 of the monitoring pixel circuit 260 cannot generate an appropriate amount of photocurrent, the bottom potential Vbtm can be made close to the target voltage Vtarget, and a decrease in the measurement accuracy of the distance measurement module 100 can be suppressed.

[0261] (First modification of the fourth embodiment)

[0262] The distance measurement module 100 according to the first modification of the fourth embodiment is different from the distance measurement module 100 according to the fourth embodiment in that the arithmetic circuit 300h also has the circuit configuration of the control circuit 210g. Hereinafter, the differences from the distance measurement module 100 according to the fourth embodiment will be described below.

[0263] Figure 37This is a diagram showing a configuration example of a pixel array unit 240h and a control circuit 210h according to a first modification of the fourth embodiment. As Figure 37 shown, the ranging module is different from the ranging module 100 according to the fourth embodiment in that the arithmetic circuit 300h also has the circuit configuration of the control circuit 210g. Thus, by integrating the circuit structure of the control circuit 210j and the circuit structure of the arithmetic circuit 300h in the same element, further miniaturization of the light detection element 200a can be achieved.

[0264] (Second modification of the fourth embodiment)

[0265] The ranging module 100 according to the second modification of the fourth embodiment is different from the ranging module 100 according to the fourth embodiment in that the control circuit 210j also has the circuit configuration of the arithmetic circuit 300h, and the pixel array unit 240b is separated from the control circuit 210j. Hereinafter, the differences from the ranging module 100 according to the fourth embodiment will be described.

[0266] Figure 38 This is a diagram showing a configuration example of a pixel array unit 240j and a control circuit 210j according to the second modification of the fourth embodiment. The ranging module is different from the ranging module 100 according to the fourth embodiment in that the circuit configuration of the arithmetic circuit 300h is also included in the control circuit 210j, and the pixel array unit 240b and the control circuit 210j are separated. In addition, a storage unit 240jb is arranged on the control circuit 210j side and stores temperatures T1b and T1a.

[0267] With this configuration, the pixel array unit 240j can include an imaging pixel circuit 250, a monitoring pixel circuit 260, a VBD monitoring circuit 270, a temperature monitoring circuit 280, and a storage unit (memory) 290, so as to further improve the versatility of the pixel array unit 240j.

[0268] (Fifth embodiment)

[0269] The ranging module 100 according to the fifth embodiment is different from the ranging module 100 according to the fourth embodiment in that the VBD monitoring circuit 270k includes the circuit configuration of a smoothing circuit 400, a reaction times counter 402, and a threshold determination circuit 404 in the control circuit 210j. Hereinafter, the differences from the ranging module 100 according to the fourth embodiment will be described.

[0270] Figure 39 This is a diagram showing a circuit configuration example of the VBD monitoring circuit 270k according to the fifth embodiment. As Figure 39As shown, the differences from the ranging module 100 according to the fourth embodiment will be described, where the VBD monitoring circuit 270k includes a smoothing circuit 400, a reaction count counter 402, and a threshold determination circuit 404.

[0271] For example, the smoothing circuit 400 suppresses noise by adding the bottom potential Vbtm output from the VBD monitoring circuit 270k multiple times. The smoothing circuit 400 includes, for example, 11R / FIR.

[0272] The reaction count counter 402 counts the pulse signal output from the inverter 271. The threshold determination circuit 404 outputs a detection flag when the number counted by the reaction count counter 402 exceeds the reaction count threshold Cth. According to such a structure, at the end of the measurement times when the number exceeding the reaction count threshold Cth after the start of measurement, the detection flag I is output.

[0273] Figure 40 It is a diagram showing the change in the bottom potential Vbtm (which is the VBD monitoring value output from the VBD monitoring circuit 270k) when the reaction count threshold Cth is set to 1 time. (a) of the figure is a diagram showing the change L300 in the ambient light amount. The vertical axis represents the ambient light amount, and the horizontal axis represents time.

[0274] (b) of the figure is a diagram showing a modified example L302 of the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. (c) of the figure is a diagram showing the counter value L304 of the reaction count counter 402. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. (d) of the figure is a diagram showing a modification L306 of the detection flag. The vertical axis represents the high level of the detection flag, and the horizontal axis represents time. (e) is a diagram showing the variation L308 of the VBD monitoring value. The vertical axis represents the VBD monitoring value, and the horizontal axis represents time.

[0275] As shown in (a) of this figure, the ambient light amount is sufficient, and the BVBD monitoring circuit 270k plays many roles. As shown in (a) of the figure, since the threshold is set to 1, the detection flag is output from the start of the measurement operation. On the other hand, as shown by the line L308 in (e) of the figure, the smoothing circuit 400 does not play a sufficient role from the 0th to the 3rd time, and the VBD monitoring value is affected by noise. Therefore, the control of the anode potential Va of the photodiode 252 is also affected by the noise from the start of the measurement operation to the 0th to 3rd time.

[0276] Figure 41 It is a diagram showing the change in the VBD monitoring value in a slightly brighter environment where the reaction count threshold Cth is set to 1. (a) of the figure is a diagram showing the change L400 in the ambient light amount. The vertical axis represents the ambient light amount, and the horizontal axis represents time.

[0277] FIG. (b) is a diagram showing the change L402 of the cathode potential Vc of the photodiode 252. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. FIG. (c) is a diagram showing the counter value L404 of the reaction number counter 402. The vertical axis represents the cathode potential Vc, and the horizontal axis represents time. FIG. (d) is a diagram showing the change L406 of the detection flag. The vertical axis represents the high level of the detection flag, and the horizontal axis represents time. FIG. (e) is a diagram showing the change L408 of the VBD monitoring value. The vertical axis represents the VBD monitoring value, and the horizontal axis represents time.

[0278] As shown in FIG. (a), the ambient light amount is a slightly bright environment. In this environment, the statistical number of received photons decreases. Therefore, as shown in FIG. (b), as shown by the line L402, the number of changes in the cathode potential Vc decreases. Therefore, as shown by the line L404 in FIG. (c), the change in the counter number also increases the interval. On the other hand, as shown by the line L408 in FIG. (e), the smoothing circuit 400 cannot function sufficiently from the zero time to the third time, and the VBD monitoring value is affected by noise. Therefore, the control of the anode potential Va of the photodiode 252 is also affected by the noise from the start of the measurement operation to the zero to third times.

[0279] Figure 42 is a diagram showing the change of the VBD monitoring value output by the VBD monitoring circuit 270k when the reaction number threshold Cth is set to 4 times. FIGS. (a) to (c) and (e) are the same as those in Figure 40 On the other hand, in FIG. (d), since the threshold of the variation L310 of the detection flag is set to 4, the detection flag 0 is output until the third measurement. Therefore, the smoothing circuit 400 does not function sufficiently, and the temperature T based on the adjustment value delta generated by the first anode voltage adjustment amount calculation unit 304a is used to control the anode potential Va until the third measurement count when the VBD monitoring value is affected by noise. Therefore, the anode potential Va can be controlled without being affected by noise.

[0280] Figure 43 is a diagram showing the change of the VBD monitoring value output by the VBD monitoring circuit 270k when the reaction number threshold Cth is set to 4 times. FIGS. (a) to (c) and (e) are the same as those in Figure 41 Since the threshold of the change L410 of the detection flag is set to 4 in FIG. (d), the detection flag 0 is output to the third measurement. Therefore, the smoothing circuit 400 does not function sufficiently, and the temperature T based on the adjustment value delta generated by the first anode voltage adjustment amount calculation unit 304a (see Figure 32)The temperature T of the generated adjustment value Δ controls the anode potential Va until the third measurement count at which the VBD monitoring value is affected by noise. Therefore, the anode potential Va can be controlled without being affected by noise.

[0281] As described above, at the start of measurement where the control of the adjustment value delta generated by the second anode voltage adjustment amount calculation unit 304b (see Figure 32 ) is affected by noise, the temperature T is used to control the anode potential Va using the adjustment value delta generated by the first anode voltage adjustment amount calculation unit 304a (see Figure 32 ). Therefore, the influence of noise at the start of measurement is suppressed, and the degradation of measurement accuracy is suppressed.

[0282] Figure 44 is a flowchart showing an example of the control process during the measurement operation according to the fifth embodiment. The same processes as those in Figure 36 are denoted by the same reference numerals, and their descriptions are omitted. The threshold determination circuit 404 determines whether the counter value of the reaction number counter 402 is equal to or less than a predetermined number, for example, equal to or less than 3 (step S200). If the counter value is equal to or less than the predetermined number (Yes in step S111), the threshold determination circuit 404 sets the detection flag to 0. On the other hand, if the counter value is not equal to or less than the predetermined number (No in step S111), the threshold determination circuit 404 sets the detection flag to 1. Thereafter, the process corresponding to Figure 36 in is executed.

[0283] As described above, when the counter value is equal to or less than the predetermined number after the start of the measurement operation, the distance measurement module 100 according to the present embodiment controls the anode potential Va using the temperature T of the temperature monitoring circuit 280. Therefore, even when there is a possibility that the smoothing circuit 400 cannot maintain the processing accuracy, the bottom potential Vbtm can be made close to the target voltage Vtarget, and the degradation of the measurement accuracy of the distance measurement module 100 is suppressed.

[0284] (Sixth Embodiment)

[0285] The distance measurement module 100 according to the sixth embodiment is different from the distance measurement module 100 according to the first embodiment in that the VBD monitoring circuit 270g supplies a detection flag to the control circuit 210. Hereinafter, the differences from the distance measurement module 100 according to the first embodiment will be described below.

[0286] Figure 45It is a block diagram showing a configuration example of a pixel array unit 240k in the sixth embodiment of the present technology. The VBD monitoring circuit 270g according to the sixth embodiment is different from the ranging module 100 according to the first embodiment in that it has the same configuration as the VBD monitoring circuit 270g according to the fourth embodiment. Therefore, the VBD monitoring circuit 270g supplies a detection flag to the control circuit 210. In addition, the arithmetic circuit 300k further includes a selection unit 303h. When the detection flag is 1, the selection unit 303k outputs the output of the anode voltage adjustment amount calculation unit 302 to the control circuit 210. Note that the VBD monitoring circuit 270k according to the fifth embodiment can be used instead of the VBD monitoring circuit 270g.

[0287] Figure 46 It is a flowchart showing an example of the control process according to the sixth embodiment. The same processes as those in Figure 17 are denoted by the same reference numerals and their descriptions are omitted. When the measurement operation is turned on, the VBD monitoring circuit 270 outputs a detection flag. In the case where the detection flag is I (Yes in step S111), when the flag is I, the anode voltage adjustment amount calculation 302 acquires the bottom potential Vbtm monitored by the BVBD monitoring circuit 270 (step S112b), and the anode voltage adjustment amount calculation 302 calculates the adjustment value delta according to Expression (3) (step S114b).

[0288] On the other hand, in the case where the detection flag is 0 (No in step S111), the anode voltage absolute value calculation 301 acquires the temperature T1 from the temperature monitoring circuit 280 (step S104b). Then, the anode voltage absolute value calculation 301 calculates the adjustment value delta of the anode potential according to Expression (7) (step S106b).

[0289] As described above, in the case where the VBD monitoring circuit 270 cannot maintain accuracy, the ranging module 100 according to the present embodiment controls the anode potential Va using the temperature T of the temperature monitoring circuit 280. Therefore, even when the photodiode 252 of the monitoring pixel circuit 260 cannot generate an appropriate amount of photocurrent, the bottom potential Vbtm can be made close to the target voltage Vtarget, and a decrease in the measurement accuracy of the ranging module 100 can be suppressed.

[0290] (First modification of the sixth embodiment)

[0291] The ranging module 100 according to the first modification of the sixth embodiment is different from the ranging module 100 according to the sixth embodiment in that the control circuit 210k according to the sixth embodiment is integrally configured in the arithmetic circuit 300L. Hereinafter, the differences from the ranging module 100 according to the sixth embodiment will be described below.

[0292] Figure 47 It is a block diagram showing a configuration example of the light detection element 240L according to the first modification of the sixth embodiment of the present technology. The ranging module is different from the ranging module 100 according to the sixth embodiment in that the control circuit 210k is integrally arranged in the arithmetic circuit 300L. As described above, the control circuit 210k is integrally arranged in the arithmetic circuit 300L, so that the circuit configuration can be further reduced.

[0293] (Second modification of the sixth embodiment)

[0294] The ranging module 100 according to the second modification of the sixth embodiment is different from the ranging module 100 according to the first modification of the sixth embodiment (see Figure 47 ) in that the control circuit 210m according to the second modification of the sixth embodiment is separated from the pixel array unit 240m. Hereinafter, the differences from the ranging module 100 according to the first modification of the sixth embodiment will be described.

[0295] Figure 48 It is a block diagram showing a configuration example of the light detection element 200 according to the second modification of the sixth embodiment. The ranging module is different from the ranging module 100 according to the first modification of the sixth embodiment in that the control circuit 210m according to the second modification of the sixth embodiment is separated from the pixel array unit 240m. As described above, the control circuit 210m is separated from the pixel array unit 240h, so that the configuration of the pixel array unit 240m can be made more general.

[0296] (Seventh embodiment)

[0297] The ranging module 100 according to the seventh embodiment is different from the ranging module 100 according to the sixth embodiment (see Figure 45 ) in that the pixel array unit 240n further includes a VBD time change amount calculation unit 303. Hereinafter, the differences from the ranging module 100 according to the sixth embodiment will be described.

[0298] Figure 49 It is a block diagram showing a configuration example of the optical pixel array unit 240n in the seventh embodiment of the present technology. As Figure 49 shown, the arithmetic circuit 300n further includes a VBD time change amount calculation unit 303. The VBD time change amount calculation unit 303 has the same configuration as the VBD time change amount calculation unit 303 according to the second embodiment.

[0299] According to this embodiment, the VBD time variation calculation unit 303 stores the adjustment value delta in the first control (see Expression (3)) as the VBD time variation ΔVBD(T0) in the storage unit 290. Then, when starting the drive with the corrected anode potential abs2 in Expression (6) including the VBD time variation ΔVBD(T0), the control circuit 210 controls the anode potential of the photodiode 252. Therefore, the deviation between the bottom potential Vbtm and the target potential Vtarget caused by the time variation of the photodiode 252 can be suppressed. As described above, according to this embodiment, in addition to the effects of the ranging module 100 according to the sixth embodiment, it also has the same effects as the ranging module 100 according to the second embodiment.

[0300] (Eighth Embodiment)

[0301] The ranging module 100 according to the eighth embodiment is different from the ranging module 100 according to the second modification of the sixth embodiment in that a part of the arithmetic circuit 300m according to the second modification of the sixth embodiment (see Figure 48 ) is arranged in the pixel array unit 240, and the control circuit 210p further includes a VBD time variation calculation unit 303. Hereinafter, the differences from the ranging module 100 according to the second modification of the sixth embodiment will be described.

[0302] Figure 50 It is a block diagram showing a configuration example of the light detection element 200p according to the eighth embodiment of the present technology.

[0303] As Figure 50 shown, the control circuit 210p further includes an addition circuit 213a, a storage unit 292, and a VBD time variation calculation unit 303. The VBD time variation calculation unit 303 has the same configuration as the VBD time variation calculation unit 303 according to the second embodiment.

[0304] According to the present embodiment, the VBD time variation calculation unit 303 stores the adjustment value delta in the first control (see Expression (3)) as the VBD time variation ΔVBD(T0) in the storage unit 292. Then, the adder circuit 213a calculates the corrected anode potential abs2 in Expression (6) including the VBD time variation ΔVBD(T0). Then, the control circuit 210q controls the anode potential of the photodiode 252 at the start of driving. Therefore, the deviation between the bottom potential Vbtm and the target potential Vtarget due to the time variation of the photodiode 252 can be suppressed. As described above, according to the present embodiment, in addition to the effects of the distance measurement module 100 according to the second modification of the sixth embodiment, it also has the same effects as the distance measurement module 100 according to the second embodiment.

[0305] (Ninth Embodiment)

[0306] The distance measurement module 100 according to the ninth embodiment is different from the distance measurement module 100 according to the sixth embodiment (see Figure 45 ) in that a plurality of temperature monitoring circuits 280 and a plurality of VBD monitoring circuits 270g according to the sixth embodiment are configured. Hereinafter, the differences from the distance measurement module 100 according to the sixth embodiment will be described below.

[0307] Figure 51 is a diagram showing an arrangement example of the temperature monitoring circuit 280 and the VBD monitoring circuit 270g according to the sixth embodiment. (a) of the figure is a diagram schematically showing a plan view of the pixel array unit 240k.

[0308] (b) of the figure is a simplified diagram showing the temperature change L500 in the pixel array unit 240k. The vertical axis represents temperature, and the horizontal axis represents the position of the temperature monitoring circuit 280 and the distance to the temperature monitoring circuit 280.

[0309] (c) of the figure is a diagram showing the relationship between the error of the target potential Vartrget and the temperature change L500. The vertical axis represents the error of the target potential Varge, and the horizontal axis represents the position of the temperature monitoring circuit 280 and the distance to the temperature monitoring circuit 280. In (c) of this figure, the line L502 represents the target potential Vartrget, and represents the position change of the error L504.

[0310] As Figure 51 shown, as the distance between the temperature monitoring circuit 280 and the VBD monitoring circuit 270 increases, the measurement error of the temperature becomes larger, and the error of the anode potential abs in Expression (2) becomes larger.

[0311] Therefore, in the pixel array unit 240p according to the present embodiment, two monitoring pixel circuits 260 are arranged at positions equidistant from the midpoint in the row direction (horizontal direction) of the pixel array unit 240p in the column direction. In addition, temperature monitoring circuits 280a and 280b are arranged at symmetric positions along the row direction from the midpoint.

[0312] Figure 52 FIG. is a diagram showing an arrangement example of temperature monitoring circuits 280a and 280b and VBD monitoring circuits 270a and 270b according to the ninth embodiment. (a) of the figure is a diagram schematically showing a plan view of the pixel array unit 240k. The VBD monitoring circuits 270a and 270b have, for example, the same configuration as that of the VBD monitoring circuit 270g (see Figure 45 ).

[0313] FIG. (b) is a diagram showing a temperature change L600 in the pixel array unit 240k. The vertical axis represents temperature, and the horizontal axis represents the position in the pixel array unit 240k.

[0314] FIG. (c) is a diagram showing the relationship between the error of the target potential Vartrget and the temperature change. The vertical axis represents the error of the target potential Varge, and the horizontal axis represents the position of the temperature monitoring circuit 280 and the distance to the temperature monitoring circuit 280. In FIG. (c), the line L602 indicates the target potential Vartrget and indicates the position change of the error L604.

[0315] As shown in FIGS. (a) and (b), the temperature monitoring circuit 280 is arranged at the midpoint of the pixel array unit 240k. Therefore, the median values of the temperature monitoring circuits 280a and 280b correspond to the temperature of the temperature monitoring circuit 280. Therefore, as shown in FIG. (c), by using the median values of the temperature monitoring circuits 280a and 280b, the error of the anode potential abs in Expression (2) also approaches 0. In the drawing, the temperature change L500 in the temperature pixel array unit 240k is shown. The vertical axis represents temperature, and the horizontal axis represents the position of the temperature monitoring circuit 280 and the distance to the temperature monitoring circuit 280.

[0316] Figure 53 FIG. is a diagram showing an imaging example in the pixel array unit 240p according to the ninth embodiment. The pixel array unit is the same as the pixel array unit 240k according to the sixth embodiment (see Figure 45) is different in that it further includes a plurality of VBD monitoring circuits 270a and 270b, a plurality of temperature monitoring circuits 280a and 280b, a plurality of median calculation units 500 and 502, the median calculation unit 502, and an AND circuit 504. The median calculation unit 500 calculates the median of the output values of the temperature monitoring circuits 280a and 280b. Similarly, the median calculation unit 502 calculates the median of the output values of the VBD monitoring circuits 270a and 270b. In addition, the AND circuit 504 outputs the AND of the detection flags of the VBD monitoring circuits 270a and 270b.

[0317] According to this embodiment, two monitoring pixel circuits 260 are arranged at positions equidistant in the column direction from the midpoint in the row direction (horizontal direction) of the pixel array unit 240p. In addition, the plurality of temperature monitoring circuits 280a and 280b are symmetrically arranged in the row direction from the midpoint. Therefore, the median calculation unit 500 can detect the temperature corresponding to the position of the monitoring pixel circuit 260 by calculating the midpoint of the temperatures output from the temperature monitoring circuits 280a and 280b, and can control the anode potential Va with higher accuracy using the temperature. In addition, the median calculation unit 502 can suppress the temperature deviation by calculating the midpoint of the bottom potentials Vbtm output from the VBD monitoring circuits 270a and 270b, and can control the anode potential Va with higher accuracy.

[0318] (Tenth Embodiment)

[0319] The distance measurement module 100 according to the tenth embodiment is different from the distance measurement module 100 according to the tenth embodiment (see Figure 54 ) in that the pixel array unit 240q further includes a VBD time change amount calculation unit 303. Hereinafter, the differences from the distance measurement module 100 according to the ninth embodiment will be described below.

[0320] Figure 54 is a block diagram showing a configuration example of the pixel array unit 240q in the tenth embodiment of the present technology. As Figure 54 shown, the arithmetic circuit 300q further includes a VBD time change amount calculation unit 303. The VBD time change amount calculation unit 303 has the same configuration as the VBD time change amount calculation unit 303 according to the second embodiment.

[0321] According to the present embodiment, the VBD time variation calculation unit 303 stores the adjustment value delta in the first control (see Expression (3)) as the VBD time variation ΔVBD(T0) in the storage unit 290. Then, the control circuit 210 controls the anode potential of the photodiode 252 when starting the drive with the corrected anode potential abs2 in Expression (6) including the VBD time variation ΔVBD(T0). Therefore, the deviation between the bottom potential Vbtm and the target potential Vtarget caused by the time variation of the photodiode 252 can be suppressed. As described above, according to the present embodiment, in addition to the effects of the ranging module 100 according to the tenth embodiment, there are also effects equivalent to those of the ranging module 100 according to the second embodiment.

[0322] (Eleventh Embodiment)

[0323] The ranging module 100 according to the eleventh embodiment is different from the ranging module 100 according to the fourth embodiment (see Figure 32 ) in that a plurality of temperature monitoring circuits 280 and a plurality of VBD monitoring circuits 270g are configured. Hereinafter, the differences from the ranging module 100 according to the fourth embodiment will be described.

[0324] Figure 55 is a block diagram showing a configuration example of the pixel array unit 240r in the eleventh embodiment of the present technology. As Figure 55 shown, the pixel array unit is different from the pixel array unit 240g according to the fourth embodiment (see Figure 32 ) in that it further includes a plurality of VBD monitoring circuits 270a and 270b, a plurality of temperature monitoring circuits 280a and 280b, a plurality of median calculation units 500 and 502, a median calculation unit 502, and an AND circuit 504. The plurality of VBD monitoring circuits 270a and 270b, the plurality of temperature monitoring circuits 280a and 280b, the plurality of intermediate calculation units 500 and 502, the intermediate calculation unit 502, and the AND circuit 504 have the same configuration as the pixel array unit 240p according to the tenth embodiment (see Figure 53 ).

[0325] According to the present embodiment, two monitoring pixel circuits 260 are arranged at positions equidistant in the column direction from the midpoint in the row direction (horizontal direction) of the pixel array unit 240p. In addition, a plurality of temperature monitoring circuits 280a and 280b are arranged symmetrically in the row direction from the midpoint. Therefore, the median calculation unit 500 can detect the temperature corresponding to the position of the monitoring pixel circuit 260 by calculating the median of the temperatures output from the temperature monitoring circuits 280a and 280b, and can control the anode potential Va with higher precision using the temperature. In addition, the median calculation unit 502 can suppress the temperature deviation by calculating the median of the bottom potentials Vbtm output from the VBD monitoring circuits 270a and 270b, and can control the anode potential Va with higher precision. In addition, the present embodiment also has an effect equivalent to that of the distance measurement module 10 according to the fourth embodiment.

[0326] <<Application Example>>

[0327] The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure can also be implemented as a device installed on any type of moving body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, a construction machine, an agricultural machine (tractor), etc.

[0328] Figure 56 is a block diagram showing an example of a schematic configuration of a vehicle control system 7000, which is an example of a moving body control system to which the technology according to the embodiment of the present disclosure can be applied. The vehicle control system 7000 includes a plurality of electronic control units connected to each other via a communication network 7010. In Figure 56 the example shown, the vehicle control system 7000 includes a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an outside vehicle information detection unit 7400, an inside vehicle information detection unit 7500, and an integrated control unit 7600. The communication network 7010 connecting the plurality of control units to each other can be an in-vehicle communication network conforming to any standard, such as Controller Area Network (CAN), Local Interconnect Network (LIN), Local Area Network (LAN), FlexRay (registered trademark), etc.

[0329] Each control unit includes: a microcomputer that performs arithmetic processing according to various programs; a storage unit that stores programs executed by the microcomputer, parameters for various operations, etc.; and a drive circuit that drives various control target devices. Each control unit also includes: a network interface (I / F) for performing communication with other control units via the communication network 7010; and a communication I / F for performing communication with devices, sensors, etc. inside and outside the vehicle by wired communication or radio communication. Figure 56The functional configuration of the integrated control unit 7600 shown includes a microcomputer 7610, a general communication I / F 7620, a dedicated communication I / F 7630, a positioning unit 7640, a beacon receiving unit 7650, an in-vehicle device I / F 7660, a sound / image output unit 7670, a vehicle network I / F 7680, and a storage unit 7690. Other control units similarly include a microcomputer, a communication I / F, a storage unit, etc.

[0330] The drive system control unit 7100 controls the operation of devices related to the vehicle's drive system according to various programs. For example, the drive system control unit 7100 serves as a control device to control: a driving force generation device for generating the 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 the braking force of the vehicle, etc. The drive system control unit 7100 may have the functions of control devices such as an anti-lock braking system (ABS), electronic stability control (ESC), etc.

[0331] The drive system control unit 7100 is connected to a vehicle state detection unit 7110. The vehicle state detection unit 7110 includes, for example, at least one of the following: a gyro sensor for detecting the angular velocity of the axial rotational movement of the vehicle body, an acceleration sensor for detecting the acceleration of the vehicle, and sensors for detecting the operation amount of the accelerator pedal, the operation amount of the brake pedal, the steering angle of the steering wheel, the engine speed, or the rotational speed of the wheels, etc. The drive system control unit 7100 performs arithmetic processing using the signals input from the vehicle state detection unit 7110 to control the internal combustion engine, the drive motor, the electric power steering device, the braking device, etc.

[0332] The body system control unit 7200 controls the operation of various devices assembled on the vehicle according to various programs. For example, the body system control unit 7200 serves as a control device to control: a keyless entry system, a smart key system, an electric window device, or various lights such as headlights, reverse lights, brake lights, turn signals, fog lights, etc. In this case, the body system control unit 12020 may receive radio waves transmitted from a mobile device serving as an alternative key or signals from various switches as inputs. The body system control unit 7200 receives these input radio waves or signals to control the vehicle's door lock device, electric window device, lights, etc.

[0333] The battery control unit 7300 controls the secondary battery 7310, which serves as the power source for the drive motor, according to various programs. For example, the battery control unit 7300 receives information such as battery temperature, battery output voltage, and remaining battery charge from the battery device including the secondary battery 7310. The battery control unit 7300 performs arithmetic processing using these signals, executes temperature regulation control of the secondary battery 7310, or controls the cooling device of the battery device, etc.

[0334] The outside vehicle information detection unit 7400 detects information about the outside of the vehicle including the vehicle control system 7000. For example, the outside vehicle information detection unit 7400 is connected to at least one of the imaging unit 7410 and the outside vehicle information detection unit 7420. The imaging unit 7410 includes at least one of a time-of-flight (ToF) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. The outside vehicle information detection unit 7420 may include at least one of the following: an environmental sensor for detecting the current atmospheric conditions or weather conditions, and a surrounding information detection sensor for detecting other vehicles, obstacles, pedestrians, etc. around the vehicle including the vehicle control system 7000.

[0335] The environmental sensor can be, for example, at least one of the following: a raindrop sensor for detecting rain, a fog sensor for detecting fog, a sunshine sensor for detecting the degree of sunshine, and a snow sensor for detecting snowfall. The surrounding information detection sensor can be at least one of the following: an ultrasonic sensor, a radar device, and a LIDAR device (light detection and ranging device, or laser imaging detection and ranging device). Each of the imaging unit 7410 and the outside vehicle information detection unit 7420 can be set as an independent sensor or device, or can be set as a device in which multiple sensors or devices are integrated.

[0336] Figure 57 An example of the installation positions of the imaging unit 7410 and the outside vehicle information detection unit 7420 is shown. The imaging units 7910, 7912, 7914, 7916, and 7918 can be arranged at the positions of the front nose, side mirrors, rear bumper, rear door of the vehicle 7900, and the upper part of the windshield inside the vehicle. The imaging unit 7910 arranged at the front nose and the imaging unit 7918 arranged at the upper part of the windshield inside the vehicle mainly obtain images in front of the vehicle 7900. The imaging units 7912 and 7914 arranged at the side mirrors mainly obtain images on the sides of the vehicle 7900. The imaging unit 7916 arranged at the rear bumper or rear door mainly obtains images behind the vehicle 7900. The imaging unit 7918 arranged at the upper part of the windshield inside the vehicle is mainly used to detect vehicles, pedestrians, obstacles, signals, traffic signs, lanes, etc. in front.

[0337] Incidentally, Figure 57An example of the shooting ranges of the respective imaging units 7910, 7912, 7914, and 7916 is shown. The imaging range a represents the imaging range of the imaging unit 7910 arranged at the front nose. The imaging ranges b and c respectively represent the imaging ranges of the imaging units 7912 and 7914 arranged at the side mirrors. The imaging range d represents the imaging range of the imaging unit 7916 arranged at the rear bumper or the rear door. For example, a bird's-eye view image of the vehicle 7900 as viewed from above can be obtained by superimposing the image data imaged by the imaging units 7910, 7912, 7914, and 7916.

[0338] The out-of-vehicle information detection units 7920, 7922, 7924, 7926, 7928, and 7930 arranged at the front, rear, sides, corners of the vehicle 7900, and the upper part of the windshield inside the vehicle can be ultrasonic sensors or radar devices. The out-of-vehicle information detection units 7920, 7926, and 7930 arranged at the front nose of the vehicle 7900, the rear bumper of the vehicle 7900, the rear door, and the upper part of the windshield inside the vehicle can be LIDAR devices. These out-of-vehicle information detection units 7920 to 7930 are mainly used to detect preceding vehicles, pedestrians, obstacles, etc.

[0339] Return to Figure 56 , and continue the description. The out-of-vehicle information detection unit 7400 causes the imaging unit 7410 to image an image of the outside of the vehicle and receives the imaged image data. In addition, the out-of-vehicle information detection unit 7400 receives detection information from the out-of-vehicle information detection unit 7420 connected to the out-of-vehicle information detection unit 7400. When the out-of-vehicle information detection unit 7420 is an ultrasonic sensor, a radar device, or a LIDAR device, the out-of-vehicle information detection unit 7400 sends ultrasonic waves, electromagnetic waves, etc., and receives information about the received reflected waves. Based on the received information, the out-of-vehicle information detection unit 7400 can perform processing of detection objects (such as people, vehicles, obstacles, signs, symbols, etc. on the road surface), or perform processing of the distance to the detected object. The out-of-vehicle information detection unit 7400 can perform environment recognition processing based on the received information to recognize rainfall, fog, road surface conditions, etc. The out-of-vehicle information detection unit 7400 can calculate the distance to an object outside the vehicle based on the received information.

[0340] In addition, based on the received image data, the out-of-vehicle information detection unit 7400 can perform image recognition processing for identifying objects (such as people, vehicles, obstacles, signs, symbols, etc. on the road surface), or perform processing of the distance to the detected object. The out-of-vehicle information detection unit 7400 can perform processing such as distortion correction and alignment on the received image data, and generate a bird's-eye view image or a panoramic image by combining the image data imaged by multiple different imaging units 7410. The out-of-vehicle information detection unit 7400 can perform viewpoint conversion processing using the image data imaged by different imaging units 7410.

[0341] The in-vehicle information detection unit 7500 detects information inside the vehicle. The in-vehicle information detection unit 7500 may be connected to a driver state detection unit 7510 that detects the state of the driver. The driver state detection unit 7510 may include a camera that photographs the driver, a biosensor that detects the biometric information of the driver, a microphone that collects the sounds inside the vehicle, and the like. The biosensor may be disposed on the seat surface, the steering wheel, etc., and detects the biometric information of the passenger sitting in the seat or the driver holding the steering wheel. Based on the detection information input from the driver state detection unit 7510, the in-vehicle information detection unit 7500 may calculate the fatigue level of the driver or the degree of concentration of the driver, or may distinguish whether the driver is dozing off. The in-vehicle information detection unit 7500 may perform processing such as noise cancellation processing on the audio signal obtained by sound collection.

[0342] The integrated control unit 7600 controls the overall operation within the vehicle control system 7000 according to various programs. The integrated control unit 7600 is connected to the input unit 7800. The input unit 7800 is a device capable of input operations by the passenger, for example, a touch panel, a button, a microphone, a switch, a control lever, etc. The integrated control unit 7600 may receive the data obtained by voice recognition of the voice input via the microphone. The input unit 7800 may be a remote control device using infrared rays or other radio waves, or may be an external connection device such as a mobile phone, a personal digital assistant (PDA), etc. that supports the operation of the vehicle control system 7000. The input unit 7800 may be a camera. In this case, the passenger can input information by gesture. Alternatively, the data obtained by detecting the movement of the wearable device worn by the passenger may be input. In addition, the input unit 7800 may include an input control circuit or the like that generates an input signal based on the information input by the passenger or the like using the above input unit 7800 and outputs the generated input signal to the integrated control unit 7600. The passenger or the like can input various data and processing operation instructions to the vehicle control system 7000 by operating the input unit 7800.

[0343] The storage unit 7690 may include a read-only memory (ROM) that stores various programs executed by the microcomputer and a random access memory (RAM) that stores various parameters, operation results, sensor values, etc. In addition, the storage unit 7690 may be a magnetic storage device such as a hard disk drive (HDD), a semiconductor storage device, an optical storage device, a magneto-optical storage device, etc.

[0344] The general communication I / F 7620 is a widely used communication I / F that mediates communication with various devices existing in the external environment 7750. The general communication I / F 7620 can implement: cellular communication protocols such as Global System for Mobile Communications (GSM (registered trademark)), Worldwide Interoperability for Microwave Access (WiMAX (registered trademark)), Long Term Evolution (LTE (registered trademark)), LTE-Advanced (LTE-A), etc., or other wireless communication protocols such as Wireless LAN (also known as Wi-Fi (registered trademark)), Bluetooth (registered trademark), etc. The general communication I / F 7620 can be connected to devices (such as application servers or control servers) existing on an external network (e.g., the Internet, cloud network, or company-specific network) via a base station or access point. In addition, the general communication I / F 7620 can use peer-to-peer (P2P) technology to connect to terminals existing near the vehicle (such terminals are, for example, terminals of drivers, pedestrians, or stores, or machine-type communication (MTC) terminals).

[0345] The dedicated communication I / F 7630 is a communication I / F that supports communication protocols developed for vehicle use. The dedicated communication I / F 7630 can implement: standard protocols such as Wireless Access in Vehicular Environment (WAVE) (which is a combination of Institute of Electrical and Electronics Engineers (IEEE) 802.11p as the lower layer and IEEE 1609 as the upper layer) in the vehicle environment, Dedicated Short Range Communication (DSRC), or cellular communication protocols. The dedicated communication I / F 7630 generally performs V2X communication including one or more of the following concepts: communication between vehicle and vehicle (vehicle-to-vehicle), communication between road and vehicle (vehicle-to-infrastructure), communication between vehicle and home (vehicle-to-home), and communication between pedestrian and vehicle (vehicle-to-pedestrian).

[0346] The positioning unit 7640 can perform positioning by receiving Global Navigation Satellite System (GNSS) signals from GNSS satellites (e.g., GPS signals from Global Positioning System (GPS) satellites) and generating position information including the latitude, longitude, and altitude of the vehicle. Incidentally, the positioning unit 7640 can identify the current position by exchanging signals with a wireless access point or obtain position information from terminals such as mobile phones, Personal Handy-phone System (PHS), or smartphones with positioning functions.

[0347] The beacon receiving unit 7650 can receive radio waves or electromagnetic waves transmitted from wireless stations installed on roads, etc., to obtain information about the current position, traffic jams, road closures, required time, etc. Incidentally, the function of the beacon receiving unit 7650 can be included in the above dedicated communication I / F 7630.

[0348] The in-vehicle device I / F 7660 is a communication interface that mediates the connection between the microcomputer 7610 and various in-vehicle devices 7760 present in the vehicle. The in-vehicle device I / F 7660 can establish a wireless connection using wireless communication protocols such as wireless LAN, Bluetooth (registered trademark), near field communication (NFC), or wireless universal serial bus (WUSB). In addition, the in-vehicle device I / F 7660 can establish a wired connection via connection terminals (and cables if necessary) not shown in the figure, through universal serial bus (USB), high-definition multimedia interface (HDMI (registered trademark)), mobile high-definition link (MHL), etc. The in-vehicle devices 7760 can include at least one of the following: mobile devices and wearable devices owned by passengers, and information devices loaded into or attached to the vehicle. The in-vehicle devices 7760 can also include a navigation device that searches for a route to any destination. The in-vehicle device I / F 7660 exchanges control signals or data signals with these in-vehicle devices 7760.

[0349] The in-vehicle network I / F 7680 is an interface that mediates the communication between the microcomputer 7610 and the communication network 7010. The in-vehicle network I / F 7680 transmits and receives signals, etc., in accordance with a predetermined protocol supported by the communication network 7010.

[0350] The microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 according to various programs based on information obtained via at least one of the general communication I / F 7620, dedicated communication I / F 7630, positioning unit 7640, beacon receiving unit 7650, in-vehicle device I / F 7660, and in-vehicle network I / F 7680. For example, the microcomputer 7610 can calculate control target values for the driving force generation device, steering mechanism, or braking device based on the obtained information related to the inside or outside of the vehicle, and output control commands to the drive system control unit 7100. For example, the microcomputer 7610 can execute cooperative control for functions aimed at implementing an advanced driver assistance system (ADAS), which includes collision avoidance or impact buffering for the vehicle, following driving based on the inter-vehicle distance, vehicle speed holding driving, vehicle collision alarm, alarm for the vehicle deviating from the lane, etc. In addition, the microcomputer 7610 can control the driving force generation device, steering mechanism, and braking device based on the obtained information about the vehicle surrounding environment, so as to execute cooperative control for automatic driving, etc., that does not rely on the driver's operation.

[0351] The microcomputer 7610 can generate three-dimensional distance information between the vehicle and objects such as surrounding structures and people based on information obtained via at least one of the general communication I / F 7620, dedicated communication I / F 7630, positioning unit 7640, beacon receiving unit 7650, in-vehicle device I / F 7660, and vehicle network I / F 7680, and generate local map information including information on the surrounding environment where the vehicle is currently located. In addition, the microcomputer 7610 can predict risks such as vehicle collisions, approaches of pedestrians, etc., and entry into a closed road based on the obtained information, and generate an alarm signal. The alarm signal can be a signal for generating a warning sound or lighting an alarm lamp.

[0352] The sound / image output unit 7670 transmits an output signal of at least one of sound and image to an output device that can notify information visually or auditorily to the passengers of the vehicle or outside the vehicle. In Figure 56 the example, the audio speaker 7710, display unit 7720, and instrument panel 7730 are shown as output devices. The display unit 7720 can include at least one of an in-vehicle display and a head-up display. The display unit 7720 can have an augmented reality (AR) display function. The output device can be other devices other than these devices, such as headphones, wearable devices such as glasses-type displays worn by passengers, projectors, lights, etc. When the output device is a display device, the display device visually displays the results obtained through various processes executed by the microcomputer 7610, or displays information in various forms (such as text, images, tables, curves, etc.) received from other control units. In addition, when the output device is an audio output device, the audio output device converts an audio signal composed of played audio data or sound data, etc. into an analog signal and outputs the analog signal auditorily.

[0353] Incidentally, in Figure 56 the example shown, at least two control units connected to each other via the communication network 7010 can be integrated into one control unit. Alternatively, each individual control unit can include multiple control units. In addition, the vehicle control system 7000 can include other control units not shown in the figure. In addition, part or all of the functions executed by one of the control units in the above description can be assigned to another control unit. That is, predetermined arithmetic processing can be executed by any one of the control units as long as information is transmitted and received via the communication network 7010. Similarly, sensors or devices connected to one of the control units can be connected to another control unit, and multiple control units can transmit and receive detection information to and from each other via the communication network 7010.

[0354] It should be noted that for implementation with reference to Figure 1A computer program for each function of the distance measurement module 100 according to the present embodiment can be implemented in any control unit or the like. In addition, a computer-readable recording medium storing such a computer program can be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. In addition, the above computer program can be distributed via, for example, a network without using a recording medium.

[0355] In the above vehicle control system 7000, the distance measurement module 100 according to the present embodiment described with reference to Figure 1 can be applied to the integrated control unit 7600 in the application example shown in Figure 56 . For example, the distance measurement module 100 corresponds to the out-of-vehicle information detection unit 7420. For example, the out-of-vehicle information detection unit 7420 controls the anode potential of the photodiode 252 according to the temperature T of the photodiode 252 in the distance measurement module 100. Therefore, temperature fluctuations in the anode potential of the photodiode 252 can be suppressed, and the bottom potential Vbtm of the photodiode 252 can be controlled to a predetermined target potential Vtarget. In addition, the anode-cathode voltage VEX at breakdown becomes constant regardless of temperature, and a decrease in distance measurement accuracy is suppressed.

[0356] It should be noted that the present technology may have the following configurations. (1)

[0358] An optical detection element, comprising:

[0359] a photodiode that photoelectrically converts incident light and outputs a photocurrent; and

[0360] a control circuit that controls to change the potential of one end of the photodiode according to the temperature related to the photodiode. (2)

[0362] The optical detection element according to (1), wherein

[0363] the control circuit supplies a lower potential to the anode of the photodiode as the temperature is higher. (3)

[0365] The optical detection element according to (2), wherein

[0366] the photodiode is an SPAD operable in Geiger mode,

[0367] the optical detection element further includes a resistor, one end of the resistor is connected to the cathode of the photodiode, and

[0368] a predetermined potential is supplied to the other end of the resistor. (4)

[0370] The optical detection element according to (1), further comprising:

[0371] A temperature detection circuit that detects temperature, wherein,

[0372] The control circuit controls the potential according to the temperature detected by the temperature detection circuit. (5)

[0374] The light detection element according to (4) further includes:

[0375] A resistor, one end of which is connected to the cathode of the photodiode, wherein

[0376] Control is performed in the following steps:

[0377] A first mode of controlling the potential according to the temperature; and

[0378] A second mode, when a photocurrent flows through the resistor, a lower potential is supplied to the anode of the photodiode because the bottom potential of the cathode is higher. (6)

[0380] The light detection element according to (5), wherein,

[0381] After stopping supplying the potential to the anode of the photodiode, the potential is controlled a predetermined number of times in the first mode. (7)

[0383] The light detection element according to (5), wherein,

[0384] The control circuit controls the potential in the second mode after controlling the potential in the first mode. (8)

[0386] The light detection element according to (5), wherein,

[0387] In the case where a predetermined potential in the cathode cannot be detected, the control circuit controls the potential in the first mode. (9)

[0389] The light detection element according to (5) further includes:

[0390] An arithmetic circuit that calculates the potential according to the temperature, wherein

[0391] The control circuit controls the potential based on the calculation result of the arithmetic circuit. (10)

[0393] The light detection element according to (9), wherein,

[0394] The arithmetic circuit calculates the potential according to a predetermined coefficient and the temperature. (11)

[0396] The light detection element according to (10), wherein,

[0397] The arithmetic circuit also calculates a potential based on the difference between the initial bottom potential of the cathode and the target potential, where the initial bottom potential is the potential when the control in the second mode has started. (12)

[0399] The photodetection element according to (11), wherein,

[0400] The arithmetic circuit calculates a potential based on the temperature fluctuation per predetermined time. (13)

[0402] The photodetection element according to (12), further comprising:

[0403] A detection circuit that detects the minimum value of the cathode when a photocurrent flows through the resistor as the bottom potential and supplies the detected minimum value to the arithmetic circuit. (14)

[0405] The photodetection element according to (13), wherein,

[0406] The detection circuit includes a smoothing circuit that performs a smoothing calculation including a predetermined number of bottom potentials before imaging, and

[0407] The predetermined number of imaging times in the first mode corresponds to the predetermined number of times before imaging. (15)

[0409] The photodetection element according to (14), wherein,

[0410] The predetermined number of imaging times in the first mode is one at activation. (16)

[0412] The photodetection element according to (15), further comprising:

[0413] A pixel array unit, wherein a plurality of pixel circuits each including a resistor and a photodiode are arranged in a two-dimensional matrix; wherein,

[0414] At least two temperature detection circuits are configured at different positions of the element in which the pixel array unit is configured, and

[0415] The control circuit performs control to change the potential of one end of each photodiode in the plurality of pixel circuits based on each temperature detected by each of the temperature detection circuits. (17)

[0417] The photodetection element according to (16), further comprising:

[0418] Pixel array unit, wherein a plurality of pixel circuits each including a resistor and a photodiode are arranged in a two-dimensional matrix; wherein,

[0419] each of at least two pixel circuits among the plurality of pixel circuits includes a detection circuit, and

[0420] the control circuit controls to change the potential of one end of each photodiode in the plurality of pixel circuits based on each potential detected by the detection circuit. (18)

[0422] The light detection element according to (17), wherein,

[0423] the arithmetic circuit and the control circuit are integrally configured in the same element. (19)

[0425] The light detection element according to (18), further comprising:

[0426] a power supply circuit that provides the potential of the anode of each of the plurality of pixel circuits, wherein

[0427] the control circuit controls the power supply circuit. (20)

[0429] The electronic device includes:

[0430] the light detection element according to (1); and

[0431] a light emitting unit configured to emit measurement light synchronized with the timing of changing the potential.

[0432] Aspects of the present disclosure are not limited to the above-described respective embodiments, but include various modifications that can be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the above. That is, various additions, modifications, and partial deletions can be made without departing from the concept, idea, and spirit of the present disclosure obtained from the content defined in the claims and their equivalents.

[0433] List of reference symbols

[0434] 1 Smart phone

[0435] 200 to 200r Light detection element

[0436] 210 to 210h Control circuit

[0437] 220 Anode voltage supply power source

[0438] 251 Resistor

[0439] 270 VBD monitoring circuit

[0440] 280 Temperature monitoring circuit

[0441] 300 to 300r arithmetic circuit.

Claims

1. A light detection element, comprising: a photodiode that photoelectrically converts incident light and outputs a photocurrent; and a control circuit that performs control to change the potential of one end of the photodiode according to the temperature associated with the photodiode.

2. The light detection element according to claim 1, wherein the control circuit supplies a lower potential to the anode of the photodiode as the temperature is higher.

3. The light detection element according to claim 2, wherein the photodiode is a SPAD capable of operating in Geiger mode, the light detection element further includes a resistor, one end of which is connected to the cathode of the photodiode, and a predetermined potential is supplied to the other end of the resistor.

4. The light detection element according to claim 1, further comprising: a temperature detection circuit that detects the temperature, wherein the control circuit controls the potential according to the temperature detected by the temperature detection circuit.

5. The light detection element according to claim 4, further comprising: a resistor, one end of which is connected to the cathode of the photodiode, wherein control is performed in the following modes: a first mode, controlling the potential according to the temperature; and a second mode, when the photocurrent flows through the resistor, supplying a lower potential to the anode of the photodiode as the bottom potential at the cathode is higher.

6. The light detection element according to claim 5, wherein after stopping supplying the potential to the anode of the photodiode, the potential is controlled in the first mode until a predetermined number of times.

7. The light detection element according to claim 5, wherein the control circuit controls the potential in the second mode after controlling the potential in the first mode.

8. The light detection element according to claim 5, wherein in a case where a predetermined potential in the cathode cannot be detected, the control circuit controls the potential in the first mode.

9. The light detection element according to claim 5, further comprising: an arithmetic circuit that calculates the potential according to the temperature, wherein the control circuit controls the potential based on the calculation result of the arithmetic circuit.

10. The light detection element according to claim 9, wherein the arithmetic circuit calculates the potential according to a predetermined coefficient and the temperature.

11. The light detection element according to claim 10, wherein the arithmetic circuit further calculates the potential based on the difference between the initial bottom potential of the cathode and the target potential, the initial bottom potential being the potential when the control in the second mode is started.

12. The light detection element according to claim 11, wherein the arithmetic circuit calculates the potential based on the fluctuation of the temperature at every predetermined time.

13. The light detection element according to claim 12, further comprising: a detection circuit that detects the minimum value of the cathode as the bottom potential when the photocurrent flows through the resistor and supplies the detected minimum value to the arithmetic circuit.

14. The light detection element according to claim 13, wherein The detection circuit includes a smoothing circuit that performs a smoothing calculation of a predetermined number of the bottom potentials before imaging, and the predetermined number of imaging times in the first mode corresponds to the predetermined number before the imaging.

15. The light detection element according to claim 14, wherein, the predetermined number of imaging times in the first mode is one time at activation.

16. The light detection element according to claim 15, further comprising: a pixel array unit, wherein a plurality of pixel circuits each including the resistor and the photodiode are arranged in a two-dimensional matrix, wherein at least two of the temperature detection circuits are configured at different positions of the element in which the pixel array unit is configured, and the control circuit performs control to change the potential of one end of each photodiode in the plurality of pixel circuits based on each temperature detected by each of the temperature detection circuits.

17. The light detection element according to claim 16, further comprising: a pixel array unit, wherein a plurality of pixel circuits each including the resistor and the photodiode are arranged in a two-dimensional matrix, wherein each of at least two pixel circuits in the plurality of pixel circuits includes the detection circuit, and the control circuit performs control to change the potential of one end of each photodiode in the plurality of pixel circuits based on each potential detected by the detection circuit.

18. The light detection element according to claim 17, wherein, the arithmetic circuit and the control circuit are integrally configured in the same element.

19. The light detection element according to claim 18, further comprising: a power supply circuit that supplies the potential of the anode of each of the plurality of pixel circuits, wherein the control circuit controls the power supply circuit.

20. An electronic device, comprising: the light detection element according to claim 1; and a light emitting unit configured to emit measurement light synchronized with the timing of changing the potential.

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