Light receiving element and ranging system

Abstract

The present technology relates to an optical receiving element and a ranging system in which power consumption can be reduced. The light receiving element includes: a pixel including an SPAD; a first transistor that sets a cathode voltage of the SPAD to a first negative voltage; the voltage conversion circuit is used for converting the cathode voltage of the SPAD and outputting the converted cathode voltage when the photons are incident; and an output unit that outputs a detection signal indicating photon incidence on the SPAD based on the converted cathode voltage. The present technology can be applied, for example, to a ranging system that detects a distance to an object in a depth direction.

Description

[0001] This application is a divisional application. The application number of the parent application is 201980054401.6, the application date is August 16, 2019, and the name of the invention is “Light receiving element and ranging system”. Technical Field

[0002] The present technology relates to a light receiving element and a distance measuring system, and more particularly, to a light receiving element and a distance measuring system that achieve reduction in power consumption. Background Art

[0003] In recent years, distance image sensors that measure distance using the time of flight (ToF) method have attracted attention. In the distance image sensor, for example, a pixel array in which pixels using a single photon avalanche diode (SPAD) are arranged in a matrix is ​​used. In the SPAD, if a photon enters the high field PN junction region in a state where a voltage higher than the breakdown voltage is applied, avalanche amplification occurs. By detecting the moment when the current flows instantaneously when avalanche amplification occurs, the distance can be measured with high precision.

[0004] A distance image sensor in which pixels using SPADs are arranged in a matrix is ​​driven so that a part of the pixels are set as active pixels that detect photons and the remaining pixels are set as inactive pixels that do not detect photons (for example, see Patent Document 1).

[0005] Citation List

[0006] Patent Documents

[0007] Patent document 1: US2016 / 0284743 A Summary of the invention

[0008] Problems to be solved by the present invention

[0009] As described above, it is necessary to apply a voltage higher than the breakdown voltage to the SPAD, which may easily lead to greater power consumption of the driving circuit that drives the SPAD and the signal processing circuit after the SPAD. In order to solve this problem, it is desired to further reduce the power consumption.

[0010] The present technology has been made in view of such circumstances, and aims at reducing power consumption.

[0011] Solution to the problem

[0012] According to the first aspect of the present technology, a light receiving element includes: a pixel, which includes a SPAD; a first transistor, configured to set the cathode voltage of the SPAD to a first negative voltage; a voltage conversion circuit, configured to convert the cathode voltage of the SPAD when a photon is incident, and output the converted cathode voltage; and an output unit, configured to output a detection signal indicating the incidence of a photon on the SPAD based on the converted cathode voltage.

[0013] According to the second aspect of the present technology, the ranging system includes: an illumination device configured to radiate irradiation light; and a light receiving element configured to receive reflected light of the irradiation light, wherein the light receiving element includes a pixel, and the pixel includes a SPAD; a first transistor configured to set the cathode voltage of the SPAD to a first negative voltage; a voltage conversion circuit configured to convert the cathode voltage of the SPAD when a photon is incident and output the converted cathode voltage; and an output unit configured to output a detection signal indicating the incidence of a photon on the SPAD based on the converted cathode voltage.

[0014] According to the first aspect and the second aspect of the present technology, a SPAD is provided; a first transistor configured to set the cathode voltage of the SPAD to a first negative voltage; a voltage conversion circuit configured to convert the cathode voltage of the SPAD when a photon is incident and output the converted cathode voltage; and an output unit configured to output a detection signal indicating the incidence of a photon on the SPAD based on the converted cathode voltage.

[0015] The light receiving element and the distance measuring system may be independent devices, or may be modules to be incorporated into other devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 : is a block diagram showing a configuration example of an embodiment of a distance measurement system to which the present technology is applied.

[0017] Figure 2 It is shown Figure 1 A block diagram of a configuration example of a light receiving element in FIG.

[0018] Figure 3 is a view showing a configuration example of a first pixel circuit.

[0019] Figure 4 It is used to illustrate Figure 3 A view of the pixels in the operation.

[0020] Figure 5 is a diagram showing a setting example of active pixels and inactive pixels.

[0021] Figure 6 is a diagram showing a first wiring example of signal lines.

[0022] Figure 7 is a view showing one unit.

[0023] Figure 8 is a diagram showing a second wiring example of the signal line.

[0024] Fig. 9 It is a view for explaining the setting of the points SP according to the interval rule.

[0025] Fig.10 is a view showing a circuit configuration of a unit using a common output buffer.

[0026] Fig.11 is a view showing a configuration example of a second pixel circuit.

[0027] Fig.12 It is used to illustrate Fig.11 A view of the pixels in the operation.

[0028] Fig.13 is a view for explaining a usage example of the distance measuring system.

[0029] Fig.14 is a block diagram showing an example of a schematic configuration of a vehicle control system.

[0030] Fig.15 2 is an explanatory diagram showing an example of installation positions of the vehicle exterior information detection unit and the imaging unit. DETAILED DESCRIPTION

[0031] Embodiments for implementing the present technology (hereinafter referred to as embodiments) will be described below. Note that the description will be provided in the following order.

[0032] 1. Configuration example of ranging system

[0033] 2. Configuration example of light receiving element

[0034] 3. First Pixel Circuit Configuration Example

[0035] 4. Example of setting active pixels and inactive pixels

[0036] 5. First wiring example of detection signal line

[0037] 6. Second wiring example of detection signal line

[0038] 7. Second Pixel Circuit Configuration Example

[0039] 8. Example of using the ranging system

[0040] 9. Application examples of moving objects

[0041] <1. Configuration example of ranging system>

[0042] Figure 1 : is a block diagram showing a configuration example of an embodiment of a distance measurement system to which the present technology is applied.

[0043] The distance measuring system 11 is a system that captures a distance image using, for example, the ToF method. Here, the distance image is an image obtained by detecting the distance from the distance measuring system 11 to the depth direction of the object for each pixel, and includes a distance pixel signal based on the detected distance.

[0044] The distance measuring system 11 includes an illumination device 21 and an imaging device 22 .

[0045] The lighting device 21 includes a lighting control unit 31 and a light source 32 .

[0046] The illumination control unit 31 controls the light irradiation pattern of the light source 32 under the control of the control unit 42 of the imaging device 22. Specifically, the illumination control unit 31 controls the light irradiation pattern of the light source 32 according to the illumination code included in the illumination signal provided from the control unit 42. For example, the illumination code is a binary code of 1 (high) and 0 (low), and when the value of the illumination code is 1, the illumination control unit 31 turns on the light source 32, and when the value of the illumination code is 0, turns off the light source 32.

[0047] The light source 32 emits light of a predetermined wavelength range under the control of the illumination control unit 31. The light source 32 includes, for example, an infrared laser diode. Note that the type of the light source 32 and the wavelength range of the irradiated light can be arbitrarily set according to the purpose of the distance measuring system 11 and the like.

[0048] The imaging device 22 is a device that receives reflected light (illumination light) radiated from the illumination device 21 and reflected on the object 12 , the object 13 , etc. The imaging device 22 includes an imaging unit 41 , a control unit 42 , a display unit 43 , and a storage unit 44 .

[0049] The imaging unit 41 includes a lens 51 , a light receiving element 52 , and a signal processing circuit 53 .

[0050] The lens 51 forms an image of incident light on a light receiving surface of the light receiving element 52. Note that the lens 51 has an arbitrary configuration, and for example, the lens 51 may include a plurality of lenses.

[0051] The light receiving element 52 includes, for example, a sensor in which a single photon avalanche diode (SPAD) is used in each pixel. The light receiving element 52 receives reflected light from the object 12, the object 13, etc. under the control of the control unit 42, and supplies a pixel signal obtained as a result to the signal processing circuit 53. The pixel signal represents a digital count value obtained by counting the time from when the irradiation light is radiated from the lighting device 21 until the light receiving element 52 receives the light. A light emission timing signal indicating the timing of the light source 32 emitting light is also supplied from the control unit 42 to the light receiving element 52.

[0052] The signal processing circuit 53 performs processing on the pixel signal provided from the light receiving element 52 under the control of the control unit 42. For example, the signal processing circuit 53 detects the distance to the object for each pixel based on the pixel signal provided from the light receiving element 52, and generates a distance image indicating the distance to the object for each pixel. Specifically, the signal processing circuit 53 obtains the time (count value) from the light source 32 emitting light until each pixel of the light receiving element 52 receives light for each pixel multiple times (for example, thousands to tens of thousands of times). The signal processing circuit 53 creates a histogram corresponding to the acquired time. Then, the signal processing circuit 53 determines the time required for the light radiated from the light source 32 to return after being reflected on the object 12 or the object 13 by detecting the peak of the histogram. The signal processing circuit 53 further performs a calculation to obtain the distance to the object based on the determined time and speed of the light. The signal processing circuit 53 provides the generated distance image to the control unit 42.

[0053] The control unit 42 includes, for example, a control circuit such as a field programmable gate array (FPGA) and a digital signal processor (DSP), a processor, and the like. The control unit 42 controls the lighting control unit 31 and the light receiving element 52. Specifically, the control unit 42 provides an illumination signal to the lighting control unit 31, and provides a light emission timing signal to the light receiving element 52. The light source 32 emits illumination light according to the illumination signal. The light emission timing signal may be an illumination signal provided to the lighting control unit 31. In addition, the control unit 42 provides the distance image acquired from the imaging unit 41 to the display unit 43, and causes the distance image to be displayed at the display unit 43. In addition, the control unit 42 causes the distance image acquired from the imaging unit 41 to be stored in the storage unit 44. In addition, the control unit 42 outputs the distance image acquired from the imaging unit 41 to the outside.

[0054] The display unit 43 includes, for example, a panel display device such as a liquid crystal display device and an organic electroluminescence (EL) display device.

[0055] The storage unit 44 may include any storage device, storage medium, etc., and stores a distance image and the like.

[0056] <2. Configuration Example of Light Receiving Element>

[0057] Figure 2 is a block diagram showing a configuration example of the light receiving element 52 .

[0058] The light receiving element 52 includes a pixel driving unit 111 , a pixel array 112 , a multiplexer (MUX) 113 , a time measuring unit 114 , and an input / output unit 115 .

[0059] The pixel array 112 has a configuration in which pixels 21 that detect the incidence of photons and output detection signals indicating the detection results as pixel signals are arranged two-dimensionally in a matrix in the row direction and the column direction. Here, the row direction refers to the arrangement direction of the pixels 121 in the pixel row, that is, the horizontal direction, and the column direction refers to the arrangement direction of the pixels 121 in the pixel column, that is, the vertical direction. Although Figure 2 Due to space limitations, a configuration in which pixel array 112 has 10 rows and 12 columns of pixel arrangement is shown, but the number of rows and columns of pixel array 112 is not limited thereto, and pixel array 112 may have any number of rows and columns.

[0060] The pixel drive line 122 is wired along each row of pixels in the horizontal direction on the matrix pixel arrangement of the pixel array 112. The pixel drive line 122 transmits a drive signal for driving the pixel 121. The pixel drive unit 111 drives each pixel 121 by providing a predetermined drive signal to each pixel 121 via the pixel drive line 122. Specifically, the pixel drive unit 111 performs control to set a part of the plurality of pixels 121 arranged in two dimensions in the matrix as active pixels at a predetermined timing according to a light emission timing signal provided from the outside via the input / output unit 115, and sets the remaining pixels 121 as inactive pixels. The active pixel is a pixel that detects the incidence of a photon, and the inactive pixel is a pixel that does not detect the incidence of a photon. The detailed configuration of the pixel 121 will be described later.

[0061] Note that although Figure 2 The pixel driving line 122 is shown as one wiring, but the pixel driving line 122 may include a plurality of wirings. One end of the pixel driving line 122 is connected to an output end corresponding to each pixel row of the pixel driving unit 111 .

[0062] The MUX 113 selects an output from an active pixel according to switching between active pixels and inactive pixels within the pixel array 112. Then, the MUX 113 outputs a pixel signal input from the selected active pixel to the time measurement unit 114.

[0063] The time measurement unit 114 generates a count value corresponding to the time from when the light source 32 emits light until the active pixel receives light, based on the pixel signal of the active pixel supplied from the MUX 113 and the light emission timing signal indicating the light emission timing of the light source 32. The light emission timing signal is supplied from the outside (control unit 42 of the imaging device 22) via the input / output unit 115.

[0064] The input / output unit 115 outputs the count value of the active pixel supplied from the time measurement unit 114 to the outside (signal processing circuit 53) as a pixel signal. In addition, the input / output unit 115 supplies the emission timing signal supplied from the control unit 42 to the pixel driving unit 111 and the time measurement unit 114.

[0065] <3. First Pixel Circuit Configuration Example>

[0066] Figure 3 A configuration example of a first pixel circuit of the pixels 121 arranged in the pixel array 112 is shown.

[0067] Figure 3 The pixel 121 shown in FIG. 1 includes a SPAD 211, a transistor 212, a transistor 213, an inverter 214, a voltage conversion circuit 215, and an output buffer 216. The transistor 212 includes a P-type MOS transistor, and the transistor 213 includes an N-type MOS transistor.

[0068] The cathode of the SPAD 211 is connected to the drain of the transistor 212, and is connected to the input terminal of the inverter 214 and the drain of the transistor 213. The anode of the SPAD 211 is connected to the power supply VSPAD.

[0069] The SPAD 211 is a photodiode (single photon avalanche photodiode) that avalanche-amplifies electrons generated when incident light is incident to output a cathode voltage signal VS. For example, the power supply VSPAD to be supplied to the anode of the SPAD 211 is set to a negative bias voltage (negative potential) of -20V.

[0070] The transistor 212, which is a constant current source operating in the saturation region, performs passive quenching by acting as a quenching resistor. The source of the transistor 212 is connected to the power supply voltage VE, and the drain is connected to the cathode of the SPAD 211, the input terminal of the inverter 214, and the drain of the transistor 213. This allows the power supply voltage VE to be supplied to the cathode of the SPAD 211 as well. A pull-up resistor may also be used instead of the transistor 212 connected in series to the SPAD 211.

[0071] A voltage higher than the breakdown voltage VBD of the SPAD 211 (hereinafter referred to as over-bias) is applied to the SPAD 211 to detect light (photons) with sufficient efficiency. For example, assuming that the breakdown voltage VBD of the SPAD 211 is 20V, and a voltage 3V higher than the breakdown voltage VBD is applied, the power supply voltage VE to be supplied to the source of the transistor 212 is set to 3V.

[0072] The drain of the transistor 213 is connected to the cathode of the SPAD 211 , the input terminal of the inverter 214 , and the drain of the transistor 212 , and the source of the transistor 213 is connected to the ground (GND) The gate control signal VG is supplied from the pixel driving unit 111 to the gate of the transistor 213 .

[0073] When the pixel 121 is set as an active pixel, a Lo (low) gate control signal VG is provided from the pixel driving unit 111 to the gate of the transistor 213. Meanwhile, when the pixel 121 is set as an inactive pixel, a Hi (high) gate control signal VG is provided from the pixel driving unit 111 to the gate of the transistor 213.

[0074] When the cathode voltage VS as the input signal is Lo, the inverter 214 outputs a Hi signal VS INV , and when the cathode voltage VS is Hi, the output Lo signal VS INV In the following, the signal VS output by the inverter 214 is INV Also called inverted signal VS INV .

[0075] The voltage conversion circuit 215 converts the inverted signal VS input from the inverter 214 into INV Convert to low voltage signal VS LOW , and the low voltage signal VS LOW Output to the output buffer 216. The inverted signal VS INV The voltage conversion circuit 215 converts the signal VS having a voltage amplitude from 0V to 3V. INV Converted to a signal VS with a voltage amplitude from 0V to 1V LOW The output buffer 216 is an output unit that outputs the signal VS input from the voltage conversion circuit 215. LOW As the detection signal PFout, the detection signal PFout indicates the incidence of photons on the SPAD 211 .

[0076] exist Figure 3, the transistor 212, the transistor 213, the inverter 214, and the voltage conversion circuit 215 included in the dotted line region 221 are elements (groups) operating at the power supply voltage VE as the first power supply voltage. Meanwhile, the output buffer 216 included in the dot-dash line region 222 is an element (group) operating at the power supply voltage VDD as the second power supply voltage lower than the first power supply voltage. The power supply voltage VDD is set to 1V, for example.

[0077] Next, we will refer to Figure 4 The operation in the case where the pixel 121 is set as an active pixel is described. Figure 4 is a graph showing changes in the cathode voltage VS of the SPAD 211 according to the incidence of photons and the detection signal PFout.

[0078] First, in the case where the pixel 121 is an active pixel, the transistor 213 is turned off by the Lo gate control signal VG.

[0079] exist Figure 4 At a time before time t0 in , a power supply voltage VE (e.g., 3V) is supplied to the cathode of the SPAD 211, and a power supply VSPAD (e.g., -20V) is supplied to the anode, and thereby a reverse voltage higher than a breakdown voltage VBD (=20V) is applied to the SPAD 211, so that the SPAD 211 enters the Geiger mode. In this state, the cathode voltage VS of the SPAD 211 is the same as the power supply voltage VE.

[0080] If a photon is incident on the SPAD 211 placed in the Geiger mode, avalanche amplification occurs and current flows to the SPAD 211 .

[0081] If avalanche amplification occurs at time t0 and current flows to the SPAD 211 , current also flows to the transistor 212 through the current flowing to the SPAD 211 at time t0 and thereafter, so that a voltage drop is generated by the resistance component of the transistor 212 .

[0082] If the cathode voltage VS of the SPAD 211 becomes lower than 0V at time t2, avalanche amplification stops because the voltage is lower than the breakdown voltage VBD. Here, the cathode voltage VS becomes lower than the breakdown VBD due to the voltage drop caused by the current generated by avalanche amplification flowing to the transistor 212 and the occurrence of the voltage drop, and the operation of stopping avalanche amplification is a quenching operation.

[0083] If avalanche amplification stops, the current flowing through the resistor of the transistor 212 gradually decreases, the cathode voltage VS returns to the original power supply voltage VE again at time t4, and the pixel is placed in a state where the pixel can detect the next new photon (charging operation).

[0084] When the cathode voltage VS as the input voltage is equal to or higher than a predetermined threshold voltage Vth (= VE / 2), the inverter 214 outputs a Lo inverted signal VS INV , and when the cathode voltage VS is lower than the predetermined threshold voltage Vth, the Hi inverted signal VS is output INV The output buffer 216 also outputs a Lo detection signal PFout when the cathode voltage VS is equal to or higher than a predetermined threshold voltage Vth (= VE / 2), and outputs a Hi detection signal PFout when the cathode voltage VS is lower than a predetermined threshold voltage Vth. Figure 4 In the example of , the output buffer 216 outputs the Hi detection signal PFout during the period from time t1 to time t3.

[0085] Note that in the case where the pixel 121 is set as an inactive pixel, a Hi gate control signal VG is supplied from the pixel driving unit 111 to the gate of the transistor 213 to turn on the transistor 213. This makes the cathode voltage VS of the SPAD 211 0 V (GND) and makes the voltage between the anode and cathode of the SPAD 211 equal to or lower than the breakdown voltage VBD, so that even if a photon is incident on the SPAD 211, the SPAD 211 does not react.

[0086] <4. Example of Setting Active Pixels and Inactive Pixels>

[0087] Next, setting examples of active pixels and inactive pixels will be described.

[0088] Assuming that a plurality of adjacent pixels 121 are one point (cluster) SP, the pixel driving unit 111 determines a predetermined number of points SP predetermined in advance in the pixel array 112, and sets active pixels. In the present embodiment, the pixel driving unit 111 sets, for example, four pixels of 2×2 as one point SP, and sets 9 points SP in the pixel array 112.

[0089] Figure 5 The pixel array 112 in 256 pixels 121 includes 16 rows and 16 columns. Among the 256 pixels 121, shaded pixels 121 represent active pixels, and non-shaded pixels 121 represent inactive pixels.

[0090] Assuming that four pixels of 2×2 are regarded as one point SP, the pixel driving unit 111 sets predetermined points SP1 to SP9 in the pixel array 112 as active pixels, for example. Note that 2×2 pixels constituting one point SP will also be referred to as SP constituting pixels hereinafter. Figure 5As shown, when distinguishing the SP constituent pixels constituting a point SP, the SP constituent pixels will also be called SP constituent pixel A, SP constituent pixel B, SP constituent pixel C and SP constituent pixel D according to the position of the SP constituent pixel within the point SP.

[0091] Note that, although an example in which one dot SP includes four pixels of 2×2 and the number of dot SPs is nine will be described in the present embodiment, the configuration of pixels constituting the dot SP is not limited to four pixels of 2×2. In addition, the number of dot SPs to be set for the pixel array 112 is not limited to nine. For example, the dot SP may be set to two pixels of 2×1, nine pixels of 3×3, etc., and the number of dot SPs to be set for the pixel array 112 may be set to four, six, etc.

[0092] The pixel driving unit 111 further moves the pixel Figure 5 By adjusting the position of each point SP shown in , the resolution of the distance measuring area of ​​the imaging device 22 is maintained equal to or higher than a predetermined value.

[0093] By setting only a portion of the pixels within the pixel array 112 as active pixels in this manner, it is possible to prevent power supply fluctuations due to the instantaneous operation current becoming too large, and to prevent power supply fluctuations from affecting distance accuracy. In addition, a point is set as a target to be irradiated with laser light, and therefore, by limiting active pixels to a portion of the point SP according to laser irradiation, power consumption can be reduced.

[0094] <5. First Wiring Example of Detection Signal Line>

[0095] The wiring layout of a signal line that transmits the detection signal PFout output by each pixel 121 of the pixel array 112 as a pixel signal will be described.

[0096] Figure 6 is a diagram showing a first wiring example of a signal line that transmits a detection signal PFout.

[0097] The first wiring example is an arrangement example of signal lines in the case where a signal line that transmits the detection signal PFout is provided separately for each pixel.

[0098] In the case where a signal line is provided individually for each pixel, since the pixel array 112 includes 256 pixels 121 in 16 rows and 16 columns, the entire pixel array 112 requires 256 signal lines 241 as 16 signal lines per row. Figure 6 Due to space limitations, 16 signal lines 241 are shown arranged in a row with one signal line.

[0099] The MUX 113 selects the signal line 241 of the pixel 121 set as the active pixel among the 256 pixels 121, and acquires the detection signal PFout from the active pixel. The number of active pixels is 36, which is 4 pixels (the number of pixels in one point SP)×9 (the number of points SP), and therefore, the number of signal lines 242 output from the MUX 113 to the time measurement unit 114 becomes 36. Figure 6 Four signal lines 242 are shown, but due to space limitations, only one signal line is shown.

[0100] The time measurement unit 114 includes a time-to-digital converter (TDC) circuit corresponding to the detection signal PFout output from the 36 active pixels. Specifically, the time measurement unit 114 includes a TDC circuit (TDC_SP1_PixA to TDC_SP1_PixD) of the SP constituting pixels A to D of the point SP1, a TDC circuit (TDC_SP2_PixA to TDC_SP2_PixD) of the SP constituting pixels A to D of the point SP2, a TDC circuit (TDC_SP3_PixA to TDC_SP3_PixD) of the SP constituting pixels A to D of the point SP3, ..., a TDC circuit (TDC_SP9_PixA to TDC_SP9_PixD) of the SP constituting pixels A to D of the point SP9. Each TDC circuit generates a count value corresponding to the time from when the light source 32 emits light until the active pixel receives light from the detection signal PFout of the input active pixel and the light emission timing signal.

[0101] As described above, by providing a signal line 241 for each pixel separately, any nine points SP1 to SP9 set in the pixel array 112 can be processed. However, it is not realistic to provide a signal line 241 for each pixel separately because the number of wirings becomes very large. In addition, there is a concern that if the signal line 241 is dense, crosstalk between pixels and skew of the detection signal PFout, signal delay, etc. may occur.

[0102] <6. Second Wiring Example of Detection Signal Line>

[0103] In order to solve this problem, a second wiring example for reducing the signal lines that transmit the detection signal PFout will be described.

[0104] In the second wiring example, a plurality of adjacent pixels within the pixel array 112 are set as one unit U.

[0105] Figure 7 1 is a diagram showing one unit U in the case where 16 pixels of 4×4 are set as one unit U.

[0106] In the case where one unit U includes 16 pixels of 4×4, one unit U includes four dots SP each including 4 pixels of 2×2, and therefore, one unit U includes four groups of SP constituting pixels A to D.

[0107] The output terminals of four SP constituent pixels A included in one unit U are connected using the vertical wiring 261A, and the signal line 271A that transmits the detection signal PFout of the four SP constituent pixels A included in one unit U is set in a pixel row of a predetermined SP constituent pixel A within the unit U.

[0108] Output terminals of four SP constituent pixels B included in one unit U are connected using a vertical wiring 261B, and a signal line 271B that transmits a detection signal PFout of the four SP constituent pixels B included in one unit U is set in a pixel row of a predetermined SP constituent pixel B within the unit U.

[0109] Output terminals of four SP constituent pixels C included in one unit U are connected using a vertical wiring 261C, and a signal line 271C that transmits a detection signal PFout of the four SP constituent pixels C included in one unit U is set in a pixel row of a predetermined SP constituent pixel C within the unit U.

[0110] Output terminals of four SP constituent pixels D included in one unit U are connected using a vertical wiring 261D, and a signal line 271D that transmits a detection signal PFout of the four SP constituent pixels D included in one unit U is set in a pixel row of a predetermined SP constituent pixel D within the unit U.

[0111] Furthermore, the signal lines 271A to 271D included in one unit U are provided in pixel rows different from each other.

[0112] In this manner, by collecting the outputs of the same type of SP constituent pixels in one unit U together with one signal line 271 using the vertical wiring 261, connection with the MUX 113 can be achieved using one signal line 271 for each row of pixels in one unit U. The number of signal lines 271 per 1 unit U becomes 4.

[0113] Figure 8 Shown for Figure 7 1 is a wiring example of the signal line 271 in the case where each of the SP constituent pixels A to D within the unit U shown in 1 is put together.

[0114] Figure 8 is a second wiring example in which the signal line for transmitting the detection signal PFout is reduced.

[0115] In targeting Figure 7 As shown in FIG. 1 , when the signal line 271 is placed together for each of the SP constituent pixels A to D in the unit U, as shown in FIG. Figure 8 As shown in FIG. 1 , in the entire pixel array 112, the number of signal lines 271 to the MUX 113 becomes 64. Figure 6 The number of signal lines 271 to the MUX 113 according to the second wiring example can be significantly reduced compared to the first wiring example shown in FIG. This can improve crosstalk and skew of the detection signal PFout at each pixel 121, signal delay, and the like.

[0116] In the second wiring example, a plurality of the same type of SP constituent pixels (one of the SP constituent pixels A to D) within the unit U utilize one common signal line 271 and therefore cannot be set as active pixels at the same time.

[0117] Therefore, the pixel driving unit 111 sets a plurality of points SP for the pixel array 112 according to the following spacing rule. In the case where one unit U includes 16 pixels of 4×4, the pixel driving unit 111 determines adjacent points SP so that each SP constituent pixel of the same type (SP constituent pixels A to D) of the point SP is ranked fourth or later among other adjacent points SP in both the horizontal direction and the vertical direction. In other words, the pixel driving unit 111 determines each point SP so that a predetermined SP constituent pixel (e.g., SP constituent pixel A) in a first point SP within the pixel array 112 is separated from an SP constituent pixel of the same type (e.g., SP constituent pixel A) of a second point SP adjacent to the first point SP by three or more pixels.

[0118] Will refer to Fig. 9 The setting of the points SP according to the spacing rule is described.

[0119] For example, the SP constituent pixel D of the point SP1 is separated from the SP constituent pixel D of the same type of the point SP2 adjacent to the point SP1 by three pixels in the horizontal direction. In other words, the SP constituent pixel D of the point SP2 is the fourth pixel in the horizontal direction from the SP constituent pixel D of the same type of the adjacent point SP1.

[0120] Furthermore, in the vertical direction, the SP constituent pixel D of the point SP1 is separated from the same type of SP constituent pixel D of the point SP4 adjacent to the point SP1 by three pixels. In other words, the SP constituent pixel D of the point SP4 is the fourth pixel from the same type of SP constituent pixel D of the adjacent point SP1 in the vertical direction.

[0121] For example, in the horizontal direction, the SP constituent pixel B of the point SP5 is separated by three pixels from the same type of SP constituent pixel B of the point SP6 adjacent to the point SP5. In other words, the SP constituent pixel B of the point SP6 is the fourth pixel from the same type of SP constituent pixel B of the adjacent point SP5 in the horizontal direction.

[0122] Furthermore, in the vertical direction, the SP constituent pixel B of the point SP5 is separated from the SP constituent pixel B of the same type of the point SP8 adjacent to the point SP5 by three pixels. In other words, in the vertical direction, the SP constituent pixel B of the point SP5 is the fourth pixel from the SP constituent pixel B of the same type of the adjacent point SP5.

[0123] In the case where a plurality of points SP are set for the pixel array 112 according to such an interval rule, as shown in FIG. Fig. 9 It can be clearly seen from FIG. 1 that the number U of SP constituent pixels A to D selected as active pixels in each unit is always equal to or less than 1. Therefore, Figure 7 As shown in , a common signal line 271 can be used for each of the same type of SP constituent pixels (SP constituent pixels A to D) within the unit U.

[0124] Although an example is described in the above example in which one point SP includes four pixels (SP constituent pixels) of 2×2, the above example can also be similarly applied in the case where the number of constituent pixels of the point SP is different. For example, also in the case where one point SP includes two pixels of 2×1 (SP constituent pixel A and SP constituent pixel B), or in the case where one point SP includes six pixels of 2×3 (SP constituent pixel A, SP constituent pixel B, SP constituent pixel C, SP constituent pixel D, SP constituent pixel E, and SP constituent pixel F), by setting a plurality of points SP according to the above-mentioned spacing rule, the number of SP constituent pixels of the same type selected as active pixels in each unit U of 4×4 is always equal to or less than 1.

[0125] Next, a case where the number of pixels included in one unit U is not 16 pixels of 4×4 will be described.

[0126] For example, a case will be described where one unit U includes 25 pixels of 5 × 5. It is assumed that one point SP includes four pixels of 2 × 2 (SP constitutes pixels A to D) in a manner similar to the above example.

[0127] In the case where one unit U includes 25 pixels of 5×5, the pixel driving unit 111 determines adjacent points SP so that the corresponding SP constituent pixels A to D of the same type of the point SP are ranked fifth or later among other adjacent points SP in both the horizontal and vertical directions. In other words, the pixel driving unit 111 determines each point SP so that a predetermined SP constituent pixel (e.g., SP constituent pixel A) in the first point SP within the pixel array 112 is separated from the SP constituent pixel of the same type (e.g., SP constituent pixel A) of the second point SP adjacent to the first point SP by four or more pixels. By setting a plurality of points SP according to the spacing rule, the number of SP constituent pixels of the same type selected as active pixels in each unit U of 5×5 is always equal to or less than 1.

[0128] Next, a case will be described where one unit U includes 36 pixels of 6 × 6. It is assumed that one point SP includes four pixels of 2 × 2 (SP constitutes pixels A to D) in a manner similar to the above example.

[0129] In the case where one unit U includes 36 pixels of 6×6, the pixel driving unit 111 determines adjacent points SP so that the corresponding SP constituent pixels A to D of the same type of the point SP are ranked sixth or later among other adjacent points SP in both the horizontal and vertical directions. In other words, the pixel driving unit 111 determines each point SP so that a predetermined SP constituent pixel (e.g., SP constituent pixel A) in the first point SP within the pixel array 112 is separated from the SP constituent pixel of the same type (e.g., SP constituent pixel A) of the second point SP adjacent to the first point SP by 5 or more pixels. By setting a plurality of points SP according to the spacing rule, the number of SP constituent pixels of the same type selected as active pixels in each unit U of 6×6 is always equal to or less than 1.

[0130] The relationship between the signal line 271 commonly used in the unit U and the spacing rule can be described as follows. In the pixel array 112, when one point SP includes N×M pixels (N>0, M>0, where N and M do not become 1 at the same time) and one unit U includes L×L (L>1), one or more vertical wirings 261 are used to put the outputs of multiple SPs of the same type in one unit U together with one signal line 271. The pixel driving unit 111 determines multiple points SP in the pixel array 112 so that the corresponding SPs of the same type of the point SP are ranked Lth or later in other adjacent points SP in both the horizontal and vertical directions. This can substantially reduce the number of signal lines 271 from the pixel array 112 to the MUX 113, so that the crosstalk and skew of the detection signal PFout, signal delay, etc. can be improved.

[0131] Note that one or more elements included in corresponding SP constituent pixels between the same type of SP constituent pixels within the unit U may also be shared, and the signal line 271 may be shared between the same type of SP constituent pixels within the unit U.

[0132] For example, the same type of SP components in the unit U can be shared between pixels. Figure 3 An output buffer 216 is provided in the last stage of the first pixel circuit of the pixel 121 shown in FIG.

[0133] Fig.10 The circuit configuration of the unit U is shown, in which the same type of SPs shared within the unit U constitute the output buffer 216 between pixels.

[0134] exist Fig.10 In the embodiment, instead of the output buffer 216 provided for each pixel, one output buffer 216' shared among four SPs constituting pixels A within one unit U is provided.

[0135] Furthermore, although illustration of circuits within the pixels of the SP constituent pixels B to D is omitted, one output buffer 216 ′ is provided for four SP constituent pixels of the same type for each of the SP constituent pixels B to D in a similar manner.

[0136] Note that although Fig.10 The output buffer 216 ′ outside the unit U is shown to facilitate understanding, but the output buffer 216 ′ may be provided within a predetermined SP constituent pixel inside the unit U.

[0137] although Fig.10 An example of integrating the output buffer 216 of the corresponding pixel 121 is shown, but in the case where each pixel includes other elements such as a calculation circuit such as a MUX, a register, and an OR circuit, these elements can be shared between the same type of SP constituent pixels. In other words, the elements to be shared between the same type of SP constituent pixels within the unit U are not limited to the output buffer.

[0138] <7. Second Pixel Circuit Configuration Example>

[0139] Fig.11 A configuration example of a second pixel circuit of the pixel 121 is shown.

[0140] Note that Fig.11 In the Figure 3 The same parts as the first pixel circuit shown in FIG. 1 are shown in FIG. 1 , and descriptions of these parts will be appropriately omitted.

[0141] Fig.11The pixel 121 shown in FIG. 1 includes a SPAD 211, a transistor 212, a transistor 213, an inverter 214, and a transistor 311. The transistor 213 includes an N-type MOS transistor, and the transistors 212 and 311 include P-type MOS transistors.

[0142] Fig.11 The second pixel circuit in Figure 3 The first pixel circuits in FIG. 2 and FIG. 3 are common in that the second pixel circuit includes a SPAD 211, a transistor 212, a transistor 213, and an inverter 214. The second pixel circuit is different from the first pixel circuit in the power supply voltage to be supplied to each element.

[0143] More specifically, although the source of the transistor 213 is grounded in the first pixel circuit, the source of the transistor 213 is connected to the power supply VNEG1, which is a negative bias voltage, in the second pixel circuit. The power supply VNEG1 is set to -2 V, for example. In addition, the second pixel circuit is configured so that when the transistor 213 is turned on by the Hi selection control signal VG, the voltage between the anode and the cathode of the SPAD 211 becomes equal to or lower than the breakdown voltage VBD, and therefore, the power supply VSPAD to be supplied to the anode of the SPAD 211 is set to -22 V, which is lower than the potential of the first pixel circuit (-20 V in the above example).

[0144] Furthermore, although the source of the transistor 212 is connected to the power supply voltage VE (3V) which is the first power supply voltage in the first pixel circuit, the source of the transistor 212 is connected to the power supply voltage VDD (1V) which is the second power supply voltage lower than the first power supply voltage in the second pixel circuit. In the case where the pixel 121 is controlled as an active pixel, since the power supply voltage VDD (1V) is supplied to the cathode of the SPAD 211 via the transistor 311 and the transistor 212, the voltage between the anode and the cathode of the SPAD 211 becomes a reverse voltage of 23V, which is the same as the reverse voltage in the first pixel circuit.

[0145] also, Fig.11 The second pixel circuit in FIG. 1 is different from the first pixel circuit in that a transistor 311 including a P-type MOS transistor is newly added between the SPAD 211 and the inverter 214. More specifically, the drain of the transistor 311 is connected to the cathode of the SPAD 211 and the drain of the transistor 213, and the source of the transistor 311 is connected to the drain of the transistor 212 and the input terminal of the inverter 214. The gate of the transistor 311 is connected to the power supply VNEG2 as a negative bias. The power supply VNEG2 is set to -1V, for example.

[0146] The transistor 311 used as a voltage conversion circuit converts a signal having a cathode voltage VS of the SPAD 211 to be supplied to the drain into a signal having a voltage VIN in a positive range and outputs the signal to the inverter 214. A power source VNEG2 (-1V) of a negative bias voltage (-Vgs) the same as a transistor threshold of the transistor 311 is applied to the gate of the transistor 311. If the voltage V IN When a voltage value (0V) is reached as a voltage value increased by a transistor threshold from the power source VNEG2 (-1V), the transistor 311 is turned off. Therefore, the transistor 311 also functions as a voltage clamp circuit.

[0147] The voltage V input to the inverter 214 IN When the voltage V IN When the phase difference is Hi, the Lo detection signal PFout is output. The inverter 214 is an output unit that outputs the detection signal PFout indicating the incidence of a photon on the SPAD 211.

[0148] Fig.12 It is shown that Fig.11 Graph showing the change in potential when the pixel 121 in FIG. 1 is set as an active pixel and light is incident.

[0149] In the case of light incident, Fig.12 As shown in FIG. 1 , the cathode voltage VS of the SPAD 211 fluctuates within the range from VDD (1V) to −2V, but the voltage V to be input to the inverter 214 is IN falls within the positive range of VDD (1V) to 0V.

[0150] The voltage V to be input IN When the voltage V is equal to or higher than a predetermined threshold voltage Vth (=VDD / 2), the inverter 214 outputs the Lo detection signal PFout, and when the voltage V IN When the voltage is lower than the predetermined threshold voltage Vth, the Hi detection signal PFout is output. Fig.12 In the example of , the Hi detection signal PFout is output during the period from time t11 to time t12.

[0151] From the above, we can see that Fig.11 The transistor 213 and the transistor 311 included in the dotted line area 321 in the second pixel circuit in FIG. 1 are elements (groups) to which an overbias voltage 3V higher than the breakdown voltage VBD of the SPAD 211 is applied in a manner similar to the first pixel circuit. Meanwhile, the transistor 212 and the inverter 214 included in the dotted line area 322 are elements (groups) operating at the power supply voltage VDD.

[0152] Therefore, in the second pixel circuit, the power supply voltage VE, which is a power supply voltage higher than the power supply voltage VDD, can be eliminated, and the number of elements that need to be operated with a high voltage power supply can be reduced from four in the region 221 of the first pixel circuit to two in the region 321. The reduction of elements operated with a high voltage power supply can lead to a reduction in the number of components, a reduction in circuit area, and a reduction in power consumption. The reduction of circuits can improve signal characteristics (such as delay and skew) until the detection signal PFout reaches the time measurement unit 114.

[0153] <8. Example of using the distance measurement system>

[0154] Fig.13 : is a diagram showing a usage example of the above-mentioned distance measuring system 11.

[0155] As described below, the above-described ranging system 11 may be used in various situations where light (such as visible light, infrared light, ultraviolet light, and X-rays) is sensed.

[0156] - Devices that capture images to be provided for viewing, such as digital cameras and mobile devices with camera functionality

[0157] - To provide means for traffic, such as on-vehicle sensors for capturing images of parts in front, behind, around, inside, etc., monitoring cameras for monitoring traveling vehicles and roads, and distance sensors that measure the distance between vehicles, etc. for safe driving (such as automatic parking) and recognize the driver's state

[0158] - Devices to be set for home appliances such as TVs, refrigerators, and air conditioners to capture user's gesture images to operate the devices according to the gestures

[0159] - To provide devices for medical treatment and health care, such as endoscopes and devices for capturing blood vessel images by receiving infrared light

[0160] - To provide devices for security, such as security cameras for crime prevention and cameras for personal authentication

[0161] - To provide a device for beauty care, such as a skin inspector for capturing skin images and a microscope for capturing scalp images

[0162] - To provide devices for sports, such as sports cameras and wearable cameras for sports

[0163] - To provide devices for agriculture, such as cameras for monitoring the status of fields and crops

[0164] <9. Application examples of moving objects>

[0165] The technology according to the present disclosure (the present technology) is applicable to a variety of products. For example, the technology according to the present disclosure is implemented as a device installed on any type of mobile object such as a car, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal transportation vehicle, an airplane, a drone, a ship, and a robot.

[0166] Fig.14 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0167] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. Fig.14 In the example shown in FIG. 1 , the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside information detection unit 12030, an inside information detection unit 12040, and an integrated control unit 12050. In addition, as a functional configuration of the integrated control unit 12050, a microcomputer 12051, a sound / image output section 12052, and an in-vehicle network interface (I / F) 12053 are shown.

[0168] The driving system control unit 12010 controls the operation of the devices related to the driving system of the vehicle according to various programs. For example, the driving system control unit 12010 is used as the following control devices: a driving force generating device (such as an internal combustion engine, a driving motor, etc.) for generating the driving force of the vehicle, a driving force transmitting 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.

[0169] The body system control unit 12020 controls the operation of various devices provided to the body according to various programs. For example, the body system control unit 12020 is used as a control device for a keyless entry system, a smart key system, a power window device, or various lights such as a headlight, a reverse light, a brake light, a turn signal, a fog light, etc. In this case, a radio wave or a signal of various switches transmitted from a mobile device instead of a key may be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals, and controls the door lock device, the power window device, the lights, etc. of the vehicle.

[0170] The vehicle exterior information detection unit 12030 detects information about the exterior of the vehicle including the vehicle control system 12000. For example, the vehicle exterior information detection unit 12030 is connected to the imaging unit 12031. The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to image the exterior of the vehicle and receives the imaged image. Based on the received image, the vehicle exterior information detection unit 12030 may perform a process of detecting an object such as a person, a vehicle, an obstacle, a sign, text on the road surface, or a process of detecting its distance.

[0171] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 may output the electrical signal as an image, or may output the electrical signal as information about the measured distance. In addition, the light received by the imaging unit 12031 may be visible light, or may be invisible light such as infrared rays.

[0172] The in-vehicle information detection unit 12040 detects information about the interior of the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver state detection unit 12041 that detects the state of the driver. The driver state detection unit 12041 includes, for example, a camera that images the driver. Based on the detection information input from the driver state detection unit 12041, the in-vehicle information detection unit 12040 can calculate the driver's fatigue level or the driver's concentration level, or can determine whether the driver is dozing off.

[0173] The microcomputer 12051 can calculate a control target value for a driving force generation device, a steering mechanism, or a braking device based on information about the interior or exterior of the vehicle obtained by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and output a control command to the driving system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing functions of an advanced driver assistance system (ADAS), including collision avoidance or shock absorption of a vehicle, follow-up driving based on a following distance, vehicle speed maintenance driving, warning of a vehicle collision, warning of a vehicle leaving a lane, and the like.

[0174] In addition, the microcomputer 12051 can perform collaborative control intended for autonomous driving by controlling the drive force generating device, steering mechanism, braking device, etc. based on information about the exterior or interior of the vehicle obtained by the exterior information detection unit 12030 or the interior information detection unit 12040, which enables the vehicle to travel autonomously without depending on the driver's operation.

[0175] In addition, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information about the outside of the vehicle obtained by the vehicle exterior information detection unit 12030. For example, the microcomputer 12051 can perform cooperative control aimed at preventing glare by, for example, controlling the headlights to change from high beam to low beam according to the position of a preceding vehicle or an upcoming vehicle detected by the vehicle exterior information detection unit 12030.

[0176] The sound / image output unit 12052 sends an output signal of at least one of sound or image to an output device capable of visually or auditorily notifying the occupants of the vehicle or the outside of the vehicle of information. Fig.14 In the example of FIG. 1 , an audio speaker 12061, a display unit 12062, and a dashboard 12063 are illustrated as output devices. The display unit 12062 may include, for example, at least one of an in-vehicle display or a head-up display.

[0177] Fig.15 12031 is a diagram showing an example of the installation position of the imaging unit 12031.

[0178] exist Fig.15 In the figure, vehicle 12100 includes imaging units 12101, 12102, 12103, 12104 and 12105 as imaging unit 12031.

[0179] The imaging units 12101, 12102, 12103, 12104, and 12105 are positioned, for example, at the front nose, rearview mirror, rear bumper, rear door, and upper portion of the front windshield in the cabin of the vehicle 12100. The imaging unit 12101 disposed at the front nose in the cabin and the imaging unit 12105 disposed at the upper portion of the windshield mainly obtain images in front of the vehicle 12100. The imaging units 12102 and 12103 attached to the side mirrors mainly obtain images of areas on the sides of the vehicle 12100. The imaging unit 12104 disposed to the rear bumper or rear door mainly obtains images of the rear of the vehicle 12100. The images in front of the vehicle obtained by the imaging units 12101 and 12105 are mainly used to detect front vehicles, pedestrians, obstacles, signals, traffic signs, lanes, and the like.

[0180] in addition, Fig.15An example of imaging distances of the imaging units 12101 to 12104 is shown. Imaging distance 12111 indicates the imaging distance of the imaging unit 12101 set to the front nose. Imaging distances 12112 and 12113 respectively indicate the imaging distances of the imaging units 12102 and 12103 set to the side mirrors. Imaging distance 12114 indicates the imaging distance of the imaging unit 12104 set to the rear bumper or the rear door. For example, a bird's-eye view image of the vehicle 12100 viewed from above is obtained by superimposing image data imaged by the imaging units 12101 to 12104.

[0181] At least one of the imaging units 12101 to 12104 may have a function of obtaining distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0182] For example, the microcomputer 12051 can determine the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the time change of the distance (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104, and thereby extract the nearest three-dimensional object that is particularly present on the travel path of the vehicle 12100 and travels in substantially the same direction as the vehicle 12100 at a predetermined speed (e.g., equal to or greater than 0 km / h) as the leading vehicle. In addition, the microcomputer 12051 can pre-set the following distance to be maintained in front of the leading vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. Therefore, cooperative control intended for automatic driving can be performed, which allows the vehicle to travel autonomously without depending on the driver's operation, etc.

[0183] For example, the microcomputer 12051 can classify the three-dimensional object data on the three-dimensional object into three-dimensional object data of two-wheeled vehicles, standard-sized vehicles, large vehicles, pedestrians, electric poles, etc. and other three-dimensional objects based on the distance information obtained from the imaging units 12101 to 12104, extract the classified three-dimensional object data, and use the extracted three-dimensional object data for automatic avoidance of obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that can be visually recognized by the driver of the vehicle 12100 and obstacles that are difficult for the driver of the vehicle 12100 to visually recognize. Then, the microcomputer 12051 determines the collision risk indicating the danger of collision with each obstacle. When the collision risk is equal to or higher than the set value and therefore there is a possibility of collision, the microcomputer 12051 outputs a warning to the driver via the audio speaker 12061 or the display unit 12062, and performs forced deceleration or avoidance steering via the drive system control unit 12010. The microcomputer 12051 can thereby assist driving to avoid collisions.

[0184] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. The microcomputer 12051 may identify a pedestrian, for example, by determining whether a pedestrian exists in the imaging images of the imaging units 12101 to 12104. Such identification of pedestrians is performed, for example, by: a program that extracts feature points in the imaging images of the imaging units 12101 to 12104 that are infrared cameras; a program that determines whether it is a pedestrian by performing pattern matching processing on a series of feature points that represent the outline of an object. When the microcomputer 12051 determines that there is a pedestrian in the imaging images of the imaging units 12101 to 12104 and thereby identifies the pedestrian, the sound / image output unit 12052 controls the display unit 12062 so that a square outline for emphasis is displayed so as to be superimposed on the identified pedestrian. In addition, the sound / image output unit 12052 may also control the display unit 12062 so that an icon representing a pedestrian or the like is displayed at a desired position.

[0185] In the above, an example of a vehicle control system to which the technology related to the present disclosure can be applied is described. The technology according to the present disclosure can be applied to the imaging unit 12031 and the like within the above configuration. Specifically, for example, Figure 1 The ranging system 11 shown in the figure can be applied to the imaging unit 12031. The imaging unit 12031 is, for example, a LIDAR, and is used to detect objects around the vehicle 12100 and the distances of the objects. By applying the technology of the present disclosure to the imaging unit 12031, the accuracy of detecting the objects around the vehicle 12100 and the distances of the objects will be improved. As a result, for example, a warning of a vehicle collision can be issued at an appropriate time to prevent a traffic accident.

[0186] In addition, in this specification, a system has the meaning of a group of multiple structural elements such as devices or modules (components), and whether all the structural elements are in the same housing is not considered. Therefore, the system may be a plurality of devices stored in separate housings and connected via a network, or a device in which a plurality of modules are stored in a single housing.

[0187] Furthermore, the embodiments of the present technology are not limited to the above-described embodiments, and various changes and modifications may be made without departing from the scope of the present technology.

[0188] Note that the effects described in this specification are not limiting but merely examples, and there may be other effects than those described in this specification.

[0189] Furthermore, the present technology may also be configured as follows. (1)

[0191] The light receiving element includes

[0192] A pixel, the pixel comprising:

[0193] SPAD;

[0194] a first transistor configured to set a cathode voltage of the SPAD to a first negative voltage;

[0195] a voltage conversion circuit configured to convert the cathode voltage of the SPAD when photons are incident and output the converted cathode voltage; and

[0196] An output unit is configured to output a detection signal indicating the incidence of the photon on the SPAD based on the converted cathode voltage. (2)

[0198] The light receiving element according to (1),

[0199] Wherein, when the pixel is controlled to be an inactive pixel that does not detect incident photons, the first transistor sets the cathode voltage of the SPAD to the first negative voltage. (3)

[0201] The light receiving element according to (1) or (2), wherein the voltage conversion circuit converts a signal of the cathode voltage of the SPAD into a signal within a positive voltage range. (4)

[0203] The light receiving element according to any one of (1) to (3),

[0204] The voltage conversion circuit includes a second transistor different from the first transistor, and supplies a second negative voltage that is the same as a transistor threshold to a gate of the second transistor. (5)

[0206] The light receiving element according to (4),

[0207] Wherein, the first transistor comprises an NMOS transistor, and

[0208] The second transistor includes a PMOS transistor. (6)

[0210] The light receiving element according to any one of (1) to (5),

[0211] Wherein, when the pixel is controlled to be an active pixel for detecting the incident photon, the cathode of the SPAD is connected to a positive power supply voltage via the voltage conversion circuit and a resistance component. (7)

[0213] The light receiving element according to any one of (1) to (6),

[0214] Wherein, the output unit includes an inverter. (8)

[0216] The light receiving element according to any one of (1) to (7),

[0217] Further including:

[0218] a pixel array in which a plurality of said pixels are arranged in a matrix; and

[0219] The pixel driving unit is configured to control each pixel of the pixel array to be an active pixel that detects the incident photon or an inactive pixel that does not detect the incident photon. (9)

[0221] A distance measuring system, comprising:

[0222] an illumination device configured to radiate illumination light; and

[0223] a light receiving element configured to receive reflected light of the irradiated light,

[0224] Wherein, the light receiving element includes

[0225] Pixels, including:

[0226] SPAD;

[0227] a first transistor configured to set a cathode voltage of the SPAD to a first negative voltage;

[0228] a voltage conversion circuit configured to convert the cathode voltage of the SPAD when photons are incident and output the converted cathode voltage; and

[0229] An output unit is configured to output a detection signal indicating the incidence of the photon on the SPAD based on the converted cathode voltage.

[0230] Reference designator list

[0231] 11 Distance measurement system

[0232] 21 lighting fixtures

[0233] 22 Imaging device

[0234] 31 Lighting control unit

[0235] 32 light sources

[0236] 41 Imaging Unit

[0237] 42Control Unit

[0238] 52 light receiving element

[0239] 53 signal processing circuit

[0240] 111 pixel drive unit

[0241] 112 pixel array

[0242] U (U1 to U16) units

[0243] SP (SP1 to SP9) points

[0244] 121 pixels

[0245] 122 pixel drive lines

[0246] 211SPAD

[0247] 212, 213 transistors

[0248] 214 Inverter

[0249] 215 voltage conversion circuit

[0250] 216, 216' output buffer

[0251] 241, 242 signal lines

[0252] 261 vertical wiring

[0253] 271 (271A to 271D) signal line

[0254] 311 transistor.

Claims

1. A light receiving element, comprising: A pixel, the pixel comprising: SPAD; a first transistor configured to set a cathode voltage of the SPAD to a first negative voltage; A voltage conversion circuit configured to convert the cathode voltage of the SPAD when photons are incident and output the converted cathode voltage; as well as An output unit is configured to output a detection signal indicating the incidence of the photon on the SPAD based on the converted cathode voltage.

2. The light receiving element according to claim 1, in, In a case where the pixel is controlled as an inactive pixel that does not detect incident photons, the first transistor sets the cathode voltage of the SPAD to the first negative voltage.

3. The light receiving element according to claim 1, in, The voltage conversion circuit converts a signal of the cathode voltage of the SPAD into a signal within a positive voltage range.

4. The light receiving element according to claim 1, in, The voltage conversion circuit includes a second transistor different from the first transistor, and supplies a second negative voltage that is the same as a transistor threshold to a gate of the second transistor.

5. The light receiving element according to claim 4, in, The first transistor comprises an NMOS transistor, and The second transistor includes a PMOS transistor.

6. The light receiving element according to claim 1, in, In case the pixel is controlled as an active pixel for detecting the incidence of the photon, the cathode of the SPAD is connected to a positive power supply voltage via the voltage conversion circuit and a resistance component.

7. The light receiving element according to claim 1, in, The output unit includes an inverter.

8. The light receiving element according to claim 1, further comprising: A pixel array, in which a plurality of said pixels are arranged in a matrix; as well as The pixel driving unit is configured to control each pixel of the pixel array to be an active pixel that detects the incident photon or an inactive pixel that does not detect the incident photon.

9. A distance measurement system, comprising: an illumination device configured to radiate illumination light; as well as a light receiving element configured to receive reflected light of the irradiated light, Wherein, the light receiving element includes Pixels, including: SPAD; a first transistor configured to set a cathode voltage of the SPAD to a first negative voltage; a voltage conversion circuit configured to convert the cathode voltage of the SPAD when photons are incident and output the converted cathode voltage; and An output unit is configured to output a detection signal indicating the incidence of the photon on the SPAD based on the converted cathode voltage.

Images