Light detection device and light detection system

Abstract

A light detection device according to an embodiment of the present disclosure comprises: a plurality of pixels, each of which includes a light-receiving element capable of receiving light and outputting a current, and is capable of outputting first signals based on the currents from the light-receiving elements; a selection circuit capable of selecting and outputting, for each period, a part of the first signals from the plurality of pixels; and a plurality of conversion circuits capable of converting the first signal input via the selection circuit to a second signal that is a digital signal.

Description

Optical detection device and optical detection system

[0001] The present disclosure relates to optical detection devices and optical detection systems.

[0002] A photodetector that includes multiple SPADs (Single Photon Avalanche Diodes) and performs compressed sensing processing has been proposed (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2019-145702

[0004] In a photodetector, it is desirable to be able to reduce the circuit area.

[0005] It is desirable to provide a photodetector that can reduce the circuit area.

[0006] A photodetection device according to an embodiment of the present disclosure includes a plurality of pixels each having a light-receiving element capable of receiving light and outputting a current, and capable of outputting a first signal based on the current of the light-receiving element, a selection circuit capable of selecting and outputting a portion of the first signals of each of the plurality of pixels for each period, and a plurality of conversion circuits capable of converting the first signals input via the selection circuit into second signals that are digital signals.A photodetection system according to an embodiment of the present disclosure includes a plurality of light-emitting elements, a control circuit capable of controlling the plurality of light-emitting elements, a plurality of pixels each having a light-receiving element and capable of outputting a first signal based on the current of the light-receiving element, a selection circuit capable of selecting and outputting a portion of the first signals of each of the plurality of pixels for each period, and a plurality of conversion circuits capable of converting the first signals input via the selection circuit into second signals that are digital signals.

[0007] FIG. 1 is a block diagram illustrating an example of a schematic configuration of a light detection system according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating an example of a configuration of a pixel of a light detection device according to an embodiment of the present disclosure. FIG. 3 is a diagram illustrating another example of a configuration of a pixel of a light detection device according to an embodiment of the present disclosure. FIG. 4 is a diagram illustrating an example of a configuration of a light emitting device according to an embodiment of the present disclosure. FIG. 5 is a diagram illustrating an example of a configuration of a light detection device according to an embodiment of the present disclosure. FIG. 6 is a diagram illustrating an example of a configuration of a light detection system according to an embodiment of the present disclosure. FIG. 7 is a diagram illustrating an example of an operation of a light detection system according to an embodiment of the present disclosure. FIG. 8 is a diagram illustrating an example of an operation of a light detection system according to an embodiment of the present disclosure. FIG. 9 is a diagram illustrating an example of an operation of a light detection system according to an embodiment of the present disclosure. FIG. 10 is a diagram illustrating an example of an operation of a light detection system according to an embodiment of the present disclosure. FIG. 11 is a diagram illustrating an example of an operation of a light detection system according to an embodiment of the present disclosure. FIG. 12 is a diagram illustrating an example of a configuration of a light detection system according to a modification of the present disclosure. FIG. 13 is a block diagram illustrating an example of a schematic configuration of a vehicle control system. FIG. 14 is an explanatory diagram showing an example of the installation positions of the outside-of-vehicle information detection unit and the imaging unit.

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order: 1. Embodiment 2. Modification 3. Usage example 4. Application example

[0009] 1 is a block diagram showing an example of a schematic configuration of a light detection system according to an embodiment of the present disclosure. The light detection system 300 includes a light detection device 1 and a light emitting device 2. The light detection system 300 can be configured as a device capable of performing distance measurement, i.e., a distance measurement device (distance measurement system). The light detection system 300 is configured to be able to perform distance measurement using, for example, a time-of-flight (TOF) method.

[0010] The photodetector 1 is a device capable of detecting incident light. The photodetector 1 has a plurality of pixels P including light-receiving elements, and is configured to receive incident light and generate a signal. The photodetector 1 is a device capable of receiving light and generating a signal, and can also be called a light-receiving device. The photodetector 1 can be configured as a distance sensor, an image sensor, etc.

[0011] The pixels P of the photodetector 1 include, for example, an avalanche photodiode (APD) as a light-receiving element and are configured to receive light and output a current. The light-receiving element (light-receiving unit) of each pixel P can be configured to generate a signal in response to receiving photons. The photodetector 1 generates a signal by receiving light that has passed through an optical system (not shown) including, for example, an optical lens.

[0012] The photodetector 1 is configured using, for example, a semiconductor substrate (e.g., a silicon substrate) on which light-receiving elements of each pixel P are provided. The photodetector 1 has a region (pixel section 100) in which a plurality of pixels P are provided. As shown in the example of FIG. 1 , the photodetector 1 is provided with the pixel section 100 in which a plurality of pixels P are two-dimensionally arranged in a matrix. The pixel section 100 can also be said to be a pixel array in which a plurality of pixels P are arranged.

[0013] The light-receiving element of each pixel P may be configured as a single-photon avalanche diode (SPAD). The photodetector 1 captures incident light from a measurement object via an optical system including an optical lens. The light-receiving element receives light from the measurement object (e.g., infrared light, visible light, etc.) and generates charges through photoelectric conversion, thereby generating a photocurrent.

[0014] The light emitting device 2 has a light source unit 200 and a control unit 220. The light source unit 200 is configured to be able to generate light (optical signals). The light source unit 200 has a plurality of light emitting elements L and is configured to be able to irradiate the light onto the measurement object. The light emitting device 2 has the light source unit 200 that includes light emitting elements (i.e., light emitting regions), and can also be called a light source device.

[0015] The light-emitting element L is, for example, a laser diode (LD) and can output light (infrared light, visible light, etc.) to the outside. The light source unit 200 can, for example, generate laser light and emit the laser light to the outside. The light source unit 200 can be configured using a semiconductor laser element, for example, a vertical cavity surface-emitting laser (VCSEL).

[0016] 1, the light source unit 200 has a region 210 in which a plurality of light-emitting elements L are two-dimensionally arranged in a matrix. The region 210 can also be called an element array in which a plurality of light-emitting elements L are arranged. The region 210 is a region that includes a plurality of light-emitting elements (light-emitting regions), and can be provided as, for example, a VCSEL array.

[0017] The control unit 220 is configured to be able to control the light source unit 200. The control unit 220 is a control circuit and is configured to be able to control the plurality of light-emitting elements L of the light source unit 200. The control unit 220 can also be called a drive unit (drive circuit) configured to be able to drive the light source unit 200 (or the light-emitting elements L of the light source unit 200). The control unit 220 can also be called a light source control unit or a light source drive unit.

[0018] The control unit 220 may be configured with a plurality of circuits including, for example, a timing generator, a digital-to-analog converter (DAC), an amplifier circuit, etc., and may control the operation of the light source unit 200. The control unit 220 may be configured as a driver IC (driver circuit).

[0019] The control unit 220 is configured to be able to control, for example, the current and voltage to the light-emitting element L of the light source unit 200. The control unit 220 can supply the light source unit 200 with the current and voltage for driving the light-emitting element L of the light source unit 200, and control the light emission by the light-emitting element L (for example, the light emission timing, the light emission duration, etc.).

[0020] The light detection system 300 can irradiate a measurement object with light (e.g., laser light) using the light source unit 200 and receive the light reflected by the measurement object. In the light detection device 1, for example, reflected light (returned light) reflected by the measurement object is incident on the pixel unit 100, and an electrical signal corresponding to the reception of the reflected light is detected. The electrical signal generated by receiving the reflected light from the measurement object is a signal corresponding to the distance to the measurement object.

[0021] The light detection system 300 transmits and receives light and can measure the distance to a measurement target. The light detection device 1 is configured, for example, to detect the distance to an object (subject) that is the measurement target for each pixel P and generate image data (distance image data) related to the distance to the object. The light detection device 1 can generate, for example, a depth map.

[0022] The light detection device 1 and the light detection system 300 can also be applied to a sensor capable of detecting an event, such as an event-driven sensor (called an EVS (Event Vision Sensor), an EDS (Event Driven Sensor), or a DVS (Dynamic Vision Sensor)). The light detection device 1 and the light detection system 300 can be applied to various electronic devices.

[0023] 1 , the photodetector 1 includes a pixel unit 100, a pixel control unit 110, a signal processing unit 120, and a control unit 150. At least a part of the photodetector 1 and the light-emitting device 2 may be integrally configured. For example, a part or all of the control unit 150 and the control unit 220 may be integrally configured.

[0024] The pixel control unit 110 is configured to be able to control each pixel P of the pixel unit 100. The pixel control unit 110 is a control circuit and is configured by a plurality of circuits including, for example, a buffer, a shift register, an address decoder, etc. The pixel control unit 110 generates signals for controlling the pixels P and outputs them to each pixel P of the pixel unit 100. The pixel control unit 110 is controlled by the control unit 150 and controls the pixels P of the pixel unit 100.

[0025] The pixel control unit 110 generates signals for controlling the pixels P, such as signals for controlling a readout circuit of the pixels P, and supplies the signals to each pixel P. The pixel control unit 110 can control the reading out of pixel signals from each pixel P. The pixel control unit 110 can also be called a pixel driving unit (pixel driving circuit) configured to be able to drive each pixel P. The pixel control unit 110 and the control unit 150 can also be called a pixel control unit collectively.

[0026] The control unit 150 is configured to be able to control each unit of the photodetector 1. The control unit 150 receives an externally provided clock, data instructing an operation mode, and the like, and can also output data such as internal information of the photodetector 1. The control unit 150 is a control circuit, and has, for example, a timing generator configured to be able to generate various timing signals.

[0027] The control unit 150 controls the driving of the pixel control unit 110, the signal processing unit 120, etc. based on various timing signals (pulse signals, clock signals, etc.) generated by the timing generator. The control unit 150 can include circuits such as a PLL (Phase Locked Loop) and a DAC (Digital to Analog Converter).

[0028] The control unit 150 is configured to, for example, supply a signal for controlling the control unit 220 to the control unit 220 and control the operation of the control unit 220. The control unit 150 can be configured to be able to control the generation process of pixel signals by the pixels P of the pixel unit 100, the timing of light irradiation by the light source unit 200, etc.

[0029] The signal processing unit 120 is a signal processing circuit configured to be able to perform signal processing. The signal processing unit 120 is configured with circuits that perform various types of signal processing on signals output from each pixel P. The signal processing unit 120 is configured to include an arithmetic circuit, a memory circuit, etc., and can perform various types of signal processing such as noise reduction processing, TD (Time to Digital) conversion processing, and counting (accumulation) processing.

[0030] The signal processing unit 120 is configured to be able to acquire, for example, a signal from each pixel P and generate a signal related to the distance to the measurement target. The signal processing unit 120 can perform various signal processing on the signal from each pixel P and generate and output distance image data representing the distance to the measurement target. The signal processing unit 120 and the control unit 150 may be configured integrally. The signal processing unit 120 and the control unit 150 may include a processor and a memory.

[0031] The signal processing unit 120 generates a signal (distance signal) indicating the distance to the measurement object based on the pixel signal. For example, in the light detection system 300, the light source unit 200 repeatedly starts and stops emitting light, and repeatedly detects reflected light (returned light) from the pixel P. The signal processing unit 120 analyzes the pixel signals sequentially output from each pixel P through multiple distance measurements, and can generate and output image data (distance image data) including a distance signal for each pixel P.

[0032] The pixel unit 100, pixel control unit 110, signal processing unit 120, control unit 150, etc. may be provided on a single substrate, or may be provided separately on multiple substrates. For example, the photodetector 1 may have a structure (a stacked structure) formed by stacking multiple semiconductor layers. At least one of the light source unit 200 and the control unit 220 may be provided on the same substrate as the pixel unit 100, etc.

[0033] 2 is a diagram illustrating an example of the configuration of a pixel of a photodetector according to an embodiment. A pixel P of the photodetector 1 includes a light-receiving element 10 and a readout circuit 20. For example, a readout circuit 20 is provided for each light-receiving element 10. Note that a readout circuit 20 may be provided for multiple light-receiving elements 10. The photodetector 1 may have a configuration in which multiple pixels P share one readout circuit 20.

[0034] The light receiving element 10 is configured to receive light and generate a signal. The light receiving element 10 is, for example, a SPAD (Single Photon Avalanche Diode) and has a multiplication region (multiplication unit) capable of avalanche multiplication. The light receiving element 10 can convert incident photons into electric charges and output a signal (signal S1 in FIG. 2 ) that is an electrical signal corresponding to the incident photons. The light receiving element 10 can also be referred to as a photoelectric conversion element (photoelectric conversion unit) configured to be capable of photoelectrically converting light.

[0035] 2, the light receiving element 10 has one electrode, a cathode, electrically connected to a node N1 connected to the supply circuit 21 and the output circuit 25. The other electrode, an anode, of the light receiving element 10 is electrically connected to, for example, a wiring, an electrode, or the like to which a relatively low voltage is supplied.

[0036] 2, the anode of the light receiving element 10 is electrically connected to a potential line L2 serving as a power supply line. A voltage VSP is applied to the anode of the light receiving element 10 via the potential line L2 from a power supply unit (voltage source) capable of supplying voltage. The voltage VSP is, for example, a negative voltage.

[0037] The readout circuit 20 is configured to be able to output a signal based on the current of the light receiving element 10. The readout circuit 20 is configured to include circuits for reading out a signal based on the photocurrent flowing through the light receiving element 10, such as a supply circuit 21 and an output circuit 25. Note that the configuration of the readout circuit 20 is not limited to the example shown in the figure and can be changed as appropriate.

[0038] The supply circuit 21 is configured to be able to supply current and voltage to the light receiving element 10. The supply circuit 21 (supply unit) is electrically connected to the potential line L1 and is able to supply current and voltage to the light receiving element 10. The supply circuit 21 is configured, for example, by a current source that is able to supply current to the light receiving element 10. The potential line L1 is a wiring to which a predetermined potential (voltage) is applied. In the example shown in FIG. 2 , the potential line L1 is a power supply line to which a power supply voltage VDD is applied.

[0039] The supply circuit 21 is, for example, configured with a transistor M1. The transistor M1 is, for example, a MOS transistor (MOSFET) having terminals of a gate, a source, and a drain. In the example shown in Fig. 2, the transistor M1 is a P-type transistor (for example, a PMOS transistor). One of the source and drain of the transistor M1, which serves as a current source, is electrically connected to a potential line L1 to which a power supply voltage VDD is applied, and the other of the source and drain of the transistor M1 is electrically connected to the light receiving element 10.

[0040] The transistor M1 of the supply circuit 21 generates a current corresponding to the signal level of a signal input to its gate, and can supply the generated current to the light receiving element 10. The supply circuit 21 (supply unit) may be configured using a resistive element. The supply circuit 21 may also be configured by a switch that electrically connects or disconnects the potential line L1 and the light receiving element 10.

[0041] A voltage can be applied between the cathode and anode of the light receiving element 10, by the voltage supplied via the supply circuit 21 and the voltage VSP supplied by the potential line L2, resulting in a potential difference greater than the breakdown voltage of the light receiving element 10. In other words, the potential difference across the light receiving element 10 can be set to a potential difference greater than the breakdown voltage.

[0042] When a reverse bias voltage greater than the breakdown voltage is applied to the light receiving element 10, the element 10 enters a state in which it can operate in Geiger mode. In Geiger mode, the light receiving element 10 may experience an avalanche multiplication phenomenon in response to incident photons, generating a pulsed current. In the pixel P, a signal S1 corresponding to the photocurrent flowing through the light receiving element 10 due to the incident photons is output to the output circuit 25.

[0043] For example, when avalanche multiplication occurs and the potential difference between the electrodes of the light-receiving element 10 is small, the supply circuit 21 supplies current to the light-receiving element 10. The supply circuit 21 recharges the light-receiving element 10, making it possible for the light-receiving element 10 to operate in Geiger mode again. The supply circuit 21 can recharge the light-receiving element 10 with electric charge and recharge the voltage of the light-receiving element 10.

[0044] The output circuit 25 is configured to generate a signal Sp1 based on the signal S1 generated by the light receiving element 10. The output circuit 25 can output the signal Sp1 as a voltage signal based on the current of the light receiving element 10. The output circuit 25 is configured, for example, by an inverter (INV).

[0045] The output circuit 25 has, for example, an input section 26 and an output section 27, and can output an inverted signal of an input signal. In the example shown in Fig. 2, the output circuit 25 is configured with an INV circuit (inverter circuit). The INV circuit is configured with, for example, a PMOS transistor and an NMOS transistor connected in series between the potential line L1 and a reference potential line. As an example, the reference potential line is a wiring to which a voltage VSS (for example, 0 V) ​​is applied, i.e., a ground line (earth line).

[0046] The input section 26 of the output circuit 25 is electrically connected to, for example, the cathode of the light receiving element 10 and the supply circuit 21. In the example shown in Figure 2, the input section 26 of the output circuit 25 (i.e., the INV circuit) is electrically connected to a node N1 that connects the light receiving element 10 and the supply circuit 21.

[0047] The output circuit 25 receives the signal S1 from the light receiving element 10. The signal level of the signal S1, i.e., the voltage (potential) of the signal S1, varies depending on the current flowing through the light receiving element 10. For example, when the voltage of the signal S1 is higher than a threshold, the output circuit 25 outputs a low-level signal Sp1. When the voltage of the signal S1 is lower than the threshold, the output circuit 25 outputs a high-level signal Sp1.

[0048] 2, the INV circuit, which is the output circuit 25, transitions the voltage of the signal Sp1 from low to high when the voltage of the signal S1 becomes smaller than the threshold voltage of the INV circuit due to the reception of photons by the light receiving element 10. Furthermore, the output circuit 25 transitions the voltage of the signal Sp1 from high to low when the voltage of the signal S1 becomes larger than the threshold voltage of the INV circuit as the light receiving element 10 is recharged by the supply circuit 21.

[0049] The output circuit 25 can output the signal Sp1, which becomes a pulse signal, as a pixel signal to the signal processing unit 120 (see FIG. 1 ). In the photodetector 1, for example, the signal Sp1, which becomes a pulse signal based on the voltage of the signal S1, is output to the signal processing unit 120 as the pixel signal.

[0050] The configuration of the output circuit 25 is not limited to the above example and can be changed as appropriate. The output circuit 25 may be configured with a buffer circuit, an AND circuit, a NAND circuit, an OR circuit, a NOR circuit, etc. The read circuit 20 may include a circuit that controls the supply circuit 21.

[0051] 3 is a diagram illustrating another example of the configuration of a pixel of the photodetector according to the embodiment. The readout circuit 20 may include an output control circuit 22, as shown in the example of FIG. 3. The output control circuit 22 is, for example, configured with a transistor M2 and electrically connected to a node N1 that connects the light receiving element 10 and the supply circuit 21. In the example shown in FIG. 3, the transistor M2 is an N-type transistor (e.g., an NMOS transistor).

[0052] The output control circuit 22 (output control unit) is configured to be able to control the output of a signal from the light receiving element 10. The output control circuit 22 is controlled by a signal input to the gate of the transistor M2, and can control the timing of reading out the signal from the light receiving element 10. For example, when the transistor M2 of the output control circuit 22 is in an off state, a signal S1 corresponding to the reception of a photon can be output to the output circuit 25.

[0053] Fig. 4 is a diagram illustrating an example of the configuration of a light emitting device according to an embodiment. The light emitting device 2 may have, for example, a plurality of cells C each including a light emitting element L, and a control unit 220, as shown in the example of Fig. 4. The light emitting elements L of each cell C are arranged two-dimensionally in a matrix in the region 210, as shown in Fig. 1.

[0054] The cell C of the light-emitting device 2 includes circuits for controlling the light-emitting element L, such as a supply circuit 31 and a switch 32. The supply circuit 31 is configured to be able to supply current and voltage to the light-emitting element L. In the example shown in FIG. 4 , the supply circuit 31 (supply unit) is electrically connected between the light-emitting element L and the switch 32.

[0055] The supply circuit 31 is electrically connected to a reference potential line via a switch 32 and can supply current and voltage to the light receiving element 10. In the example shown in Fig. 4, the reference potential line is a ground line. The supply circuit 31 is configured, for example, by a current source capable of supplying current to the light emitting element L. As an example, the supply circuit 31 is configured by a transistor M3 as a current source.

[0056] 4 , the transistor M3 is an NMOS transistor. One of the source and drain of the transistor M3 is electrically connected to the light-emitting element L, and the other of the source and drain of the transistor M3 is electrically connected to a reference potential line via the switch 32. The transistor M3 of the supply circuit 31 generates a current according to the signal level of a signal input to its gate, and can supply the generated current to the light-emitting element L.

[0057] The switch 32 is configured using, for example, a transistor M4, and is electrically connected between the supply circuit 31 and the reference potential line. The transistor M4 is configured, for example, by an NMOS transistor. The transistor M4 of the switch 32 is controlled by the control unit 220 to be in an on state (conductive state) or an off state (non-conductive state).

[0058] 4, the switch 32 is configured to electrically connect or disconnect the supply circuit 31 and the reference potential line based on a signal input from the control unit 220. The control unit 220 supplies a signal for controlling the switch 32 to the switch 32, thereby controlling the switch 32 to be turned on or off.

[0059] As an example, the control unit 220 controls the switch 32 to control the current supply to the light receiving element 10 via the supply circuit 31 and to control light emission (light emission timing, light emission duration, etc.) by the light emitting element L. The control unit 220 can individually control the switch 32 for each cell C to control the light emission of the light emitting element L of each cell C. Note that the configuration of the cell C is not limited to the example shown in the figure and can be changed as appropriate.

[0060] The control unit 220 is configured to be able to execute control to selectively emit light from some of the plurality of light-emitting elements L. The control unit 220 can select different light-emitting elements L for each predetermined period (e.g., for each subframe) and perform control to emit light from each selected light-emitting element L. The control unit 220 is configured to perform processing to selectively emit light from each of the plurality of light-emitting elements L based on, for example, a value that changes for each period, such as a random number or a pseudo-random number.

[0061] The control unit 220 sequentially selects a predetermined number of light-emitting elements L from all of the light source unit 200 based on, for example, a signal (referred to as a pattern signal) whose value changes every period (unit time), and performs control to cause each of the selected predetermined number of light-emitting elements L to emit light. The control unit 220 is configured, for example, to switch the light-emitting elements L to emit light in accordance with the pattern signal indicating a pseudo-random number.

[0062] 4, the control unit 220 has a signal generation circuit 240 that can generate a pattern signal. The signal generation circuit 240 (signal generation unit) is configured to generate and output a pattern signal that indicates, for example, a pseudo-random number. The control unit 220 can select and control the light-emitting elements L (i.e., light-emitting areas) to emit light based on the pattern signal generated by the signal generation circuit 240.

[0063] As an example, the control unit 220 outputs a pattern signal representing a pseudo-random number generated by the signal generation circuit 240 to the switch 32 of each cell C, and controls the on / off of the switch 32 of each cell C, thereby controlling the light emission of each light-emitting element L of each cell C. Note that the signal generation circuit 240 may be provided outside the control unit 220.

[0064] 5 is a diagram illustrating an example of the configuration of a photodetector according to an embodiment. The signal processing unit 120 of the photodetector 1 includes, for example, a selection circuit 121, a plurality of conversion circuits 125, and an arithmetic circuit 130. The selection circuit 121 is configured to select and output a portion of the pixel signals of each of a plurality of pixels P for each period.

[0065] The selection circuit 121 is configured to be able to select and output some of the pixel signals (i.e., the signals Sp1) input from each of the multiple pixels P of the pixel unit 100. The selection circuit 121 can be configured to be able to switch signal paths so that the pixel signals of each selected pixel P are transmitted to each conversion circuit 125.

[0066] For example, the selection circuit 121 is configured to select pixel signals of different pixels P for each predetermined period (e.g., each subframe) and output the pixel signals of each selected pixel P. The selection circuit 121 can change the pixel signals of the pixels P to be transmitted in a time-division manner (at each time interval).

[0067] The selection circuit 121 is configured with, for example, a plurality of switches, a plurality of selectors (also called multiplexers), etc. The selection circuit 121 selects a plurality of pixel signals from the pixel signals output from each of the plurality of pixels P of the pixel unit 100 for each period (unit time), and outputs the selected pixel signals to a plurality of conversion circuits 125.

[0068] The selection circuit 121 sequentially selects a predetermined number of pixels P from all of the pixels P in the pixel unit 100 for each period based on, for example, a value that changes for each period, such as a random number or a pseudo-random number, and outputs pixel signals of each of the selected predetermined number of pixels P to each conversion circuit 125. The selection circuit 121 is configured to switch the pixel signals of the pixels P to be transmitted in accordance with a signal whose value changes for each period (unit time), such as a pattern signal indicating a pseudo-random number.

[0069] 5 , the signal processing unit 120 has a signal generation circuit 140 that can generate a pattern signal. The signal generation circuit 140 (signal generation unit) is configured to generate a pattern signal that indicates, for example, a pseudo-random number and output it to the selection circuit 121. The selection circuit 121 can perform selection control of the pixel signal of the pixel P to be transmitted based on the pattern signal input from the signal generation circuit 140. Note that the signal generation circuit 140 may be provided within the control unit 150.

[0070] The selection circuit 121 of the photodetection system 300 is configured to be able to selectively output pixel signals of pixels P corresponding to light-emitting elements L to be caused to emit light, as in the example schematically shown in Fig. 6. In Fig. 6, hatched light-emitting elements L schematically indicate light-emitting elements to be caused to emit light. Also, hatched pixels P typically indicate pixels P to be selected.

[0071] The signal generation circuit 240 of the light-emitting device 2 and the signal generation circuit 140 of the light-detecting device 1 are configured to generate pattern signals that indicate the same pseudo-random numbers, for example. As an example, the signal generation circuit 140 generates a pattern signal that indicates a pseudo-random number that is common to the signal generation circuit 240, i.e., the same pseudo-random number as the pseudo-random number used to control the selection of the light-emitting elements L.

[0072] The selection circuit 121 can select, for example, a pixel signal of a pixel P located corresponding to the emitting light-emitting element L (i.e., a pixel that receives reflected light of light emitted by the light-emitting element L to the measurement object) in accordance with the pattern signal generated by the signal generation circuit 140, and transmit the pixel signal to the conversion circuit 125. Note that the signal generation circuit 140 and the signal generation circuit 240 may be configured integrally.

[0073] The conversion circuit 125 is configured to be able to perform TD (Time to Digital) conversion and converts input pixel signals into digital signals. The conversion circuit 125 is a TD conversion circuit (TD conversion unit) and is configured using, for example, a flip-flop circuit, a counter circuit, etc. The conversion circuit 125 is a TDC (Time to Digital Converter).

[0074] The conversion circuit 125 is configured to be able to convert an input pixel signal (signal Sp1) into a digital signal (signal Sp2) related to the timing of light reception at the pixel P. The conversion circuit 125 is configured to convert, for example, a pixel signal, which is a pulse signal generated by the pixel P, into a digital signal corresponding to the elapsed time from when the light-emitting element L of the light source unit 200 emits light to when the light-receiving element 10 of the pixel P receives light.

[0075] The conversion circuit 125 receives pixel signals from each pixel P of the pixel unit 100 via the selection circuit 121. The conversion circuit 125 performs TD conversion processing on the pixel signals, which become pulse signals sequentially read out from each pixel P. The signal Sp1, which is the pixel signal transmitted via the selection circuit 121, is subjected to TD conversion processing by the conversion circuit 125 and converted into, for example, a signal Sp2, which is a digital signal indicating the timing of receiving reflected light from the measurement object.

[0076] In the photodetector 1, a plurality of conversion circuits 125 are provided corresponding to the number of pixel signals transmitted via the selection circuit 121. The number of conversion circuits 125 is smaller than the number of pixels P in the pixel unit 100. As an example, a conversion circuit 125 may be provided for every predetermined number of pixels P.

[0077] The conversion circuit 125 can be configured to be able to output, as a converted pixel signal, a digital signal corresponding to the time from the emission timing of the light-emitting element L to the reception timing of reflected light (return light) by the light-receiving element 10. As an example, the conversion circuit 125 converts the signal Sp1 of the pixel P, which is a pulse signal, into a signal Sp2, which is a digital signal with a predetermined number of bits, and outputs it as a signal indicating the round-trip time (i.e., time of flight) of the light.

[0078] For example, the conversion circuit 125 may measure the time from the emission timing of the light-emitting element L to the transition timing (rising edge or falling edge) of the pixel signal corresponding to the reception of reflected light as a count value, and generate a signal indicating the count value as the converted pixel signal. Based on the signal Sp1, the conversion circuit 125 may output a signal Sp2 indicating a count value corresponding to the period from the start of irradiation of the measurement object with light to the reception of reflected light from the measurement object as the converted pixel signal.

[0079] The arithmetic circuit 130 is configured to acquire the pixel signals converted into digital signals and perform arithmetic processing. The arithmetic circuit 130 (arithmetic unit) is configured to include, for example, a logic circuit, a memory, etc. The arithmetic circuit 130 is configured to generate data regarding the light reception timing for each pixel P based on the signal Sp2 output by each conversion circuit 125 and to calculate the distance to the measurement target.

[0080] 5, the arithmetic circuit 130 includes a generation circuit 131 and a generation circuit 132. The generation circuits 131 and 132 each include, for example, an adder circuit, a multiplier circuit, a memory circuit, etc., and are configured as histogram generation circuits (histogram generation units) capable of generating a histogram of pixel signals.

[0081] The generation circuit 131 is configured to be able to generate, for each predetermined period (e.g., each subframe), a histogram, i.e., a compressed histogram, of the signal values ​​(count values) of pixel signals of multiple pixels P that are selected and TD converted. The generation circuit 131 classifies, for example, multiple pixel signals (count values) obtained during the same period (e.g., subframe) into predetermined intervals (ranges), i.e., into classes (BIN), and generates histogram data D1 that indicates the distribution of the count values.

[0082] The generation circuit 131 can count (count) multiple pixel signals (i.e., count values) obtained in the same subframe collectively for each BIN, and generate histogram data D1 indicating the frequency (number) of the count values. For example, the count values ​​of different pixels are measured for each subframe and integrated (summed up) for each BIN, and different histogram data D1 is generated for each subframe.

[0083] The generation circuit 132 is configured to be able to generate a histogram of count values ​​corresponding to the signal values ​​of pixel signals, i.e., the round-trip time of light, for each pixel P. The generation circuit 132 is configured to reconstruct histogram data D2 for each pixel P based on the histogram data D1 generated by the generation circuit 131, for example. The generation circuit 132 can calculate (estimate) the histogram data D2 for each pixel P of the pixel unit 100 by analyzing multiple pieces of histogram data D1 for each predetermined period.

[0084] The generation circuit 132 performs, for example, a transformation process (e.g., a discrete cosine transform for sparsification, an inverse sparse transform, or the like) on the compressed histogram data D1 for each subframe to generate histogram data D2 for each pixel P. The generation circuit 132 can generate, for example, data relating to the correspondence between the class (BIN) and the frequency (number) of the count value for each pixel P of the pixel unit 100 as the histogram data D2.

[0085] The generation circuit 132 is also configured to be able to calculate the distance to the measurement target based on the peak value (maximum value) in the histogram of pixel signal values. The generation circuit 132 calculates (estimates) the difference between the start time of light irradiation and the arrival time of reflected light, i.e., the round-trip time (time of flight) of light, based on, for example, a count value (or BIN) that indicates the peak value of frequency in the histogram data D2.

[0086] The generation circuit 132 is configured to calculate the distance between the light detection device 1 (or the light detection system 300) and the measurement object using, for example, the calculated round-trip time. The generation circuit 132 calculates the distance to the object for each pixel P and generates a distance signal related to the distance to the object. In the light detection system 300, the distance to the measurement object is determined based on the time it takes for light irradiated from the light source unit 200 to be reflected by the measurement object and reach the light detection device 1.

[0087] The arithmetic circuit 130 can generate distance image data including a distance signal for each pixel P using the generation circuit 132 and output the data to the outside of the light detection device 1. In this way, in the light detection system 300 according to this embodiment, the arithmetic circuit 130 can achieve multiple ranging points by compressed sensing. The light detection system 300 according to this embodiment will be further described below.

[0088] 7 to 10 are diagrams illustrating an example of the operation of the light detection system according to the embodiment. In Fig. 7, the hatched light-emitting elements L are schematic light-emitting elements L that are selected by the control unit 220 for each subframe and emit light. The hatched pixels P are schematic pixels P that are selected for each subframe.

[0089] The control unit 220 of the light-emitting device 2 selects multiple light-emitting elements L for each subframe (in Figure 7, for each subframe from the first subframe to the Mth subframe within one frame) based on, for example, a pattern signal indicating a pseudo-random number generated by the signal generation circuit 240, and controls the selected multiple light-emitting elements L to emit light.

[0090] 7 , for example, based on a pattern signal indicating pseudo-random numbers generated by the signal generation circuit 140, the selection circuit 121 of the photodetection device 1 selects, for each subframe, a pixel signal of a pixel P corresponding to a light-emitting element L to be caused to emit light, and reads out the pixel signal to the conversion circuit 125. A pixel signal Sp1 input to the conversion circuit 125 is converted by TD conversion into a digital signal Sp2, which is output to the arithmetic circuit 130.

[0091] The generation circuit 131 of the arithmetic circuit 130 generates histogram data D1 representing a compressed histogram for each subframe using signals Sp2 of the selected pixels P, as shown in FIG. ｋ，１ is the frequency of the kth [BIN] count value (i.e., the frequency (number) of count values), and can be expressed, for example, by the following equation (1).

[0092] In addition, in formula (1), x ｋ，１ ​~x ｋ，Ｎ is a signal to be calculated (restored), and is the frequency (number) of the k-th count value of each of the N pixels P in the pixel unit 100. As shown in equation (1), y ｋ，１ is x ｋ，１ ~x ｋ，Ｎ are weighted (for example, "1" for selected pixels and "0" for non-selected pixels), and the result indicates a value obtained by product-sum calculation.

[0093] As shown in the example of FIG. 8, the arithmetic circuit 130 calculates the y ｋ，１ From the Kth [BIN]th y K，１ The arithmetic circuit 130 generates a histogram representing up to x for each subframe, and obtains M histograms. As will be described later, the arithmetic circuit 130 calculates x using the M histograms. ｋ，１ ~x ｋ，Ｎ A process for estimating the following may be performed.

[0094] y obtained from the first to Mth frames ｋ，１ ~y ｋ，M is x ｋ，１ ~x ｋ，Ｎ Using a matrix Φ, for example, this can be expressed by the following equations (2) and (3): The matrix Φ is determined according to a pattern signal indicating the pseudo-random numbers described above, and represents weights (for example, "1") corresponding to selected pixels and weights (for example, [0]) corresponding to non-selected pixels for each subframe.

[0095] By multiplying the original signal (i.e., the signal to be restored) x by the matrix Ψ for sparsification, a signal α that sparsely represents the original signal x is expressed by the following equation (4). Also, y ｋ = Φx ｋ =ΦΨ -1 Using α, the following equation (5) is obtained.

[0096] The generation circuit 132 of the arithmetic circuit 130 performs optimization processing to calculate a plausible estimated solution of equation (5). Then, the generation circuit 132 performs sparse inverse transformation using the following equation (6) to calculate the signal x to be restored (i.e., the count of each pixel). ​​In addition, the generation circuit 132 may use the technology described in the non-patent document (Mimura Kazufumi, “Reconstruction of Sparse Information and Its Algorithm,” Research Institute for Mathematical Sciences, Vol. 1803, pp. 26-56, 2012) as the optimization process.

[0097] As described above, the generation circuit 132 performs conversion processing on the histogram data D1 to generate histogram data D2 for each pixel P of the pixel unit 100, as schematically shown in Fig. 9. In the example shown in Fig. 9, the generation circuit 132 reconstructs histogram data D2 for the first pixel to the Nth pixel.

[0098] 10 , the generation circuit 132 calculates a distance signal for each pixel P by performing a distance measurement value calculation using histogram data D2 for each pixel P. The generation circuit 132 can generate data including distance information for each pixel P (depth data).

[0099] 11 is a diagram illustrating an example of the operation of the light detection system according to the embodiment. As shown in the example of FIG. 11 , the control unit 220 of the light emitting device 2 changes the light emission pattern, i.e., changes the number of light emitting elements L to emit light, for each subframe based on the pattern signal of the signal generating circuit 240.

[0100] As shown in the example of FIG. 11 , the signal processing unit 120 of the photodetection device 1 changes the pixel selection pattern, i.e., changes the multiple pixels P selected by the selection circuit 121, for each subframe based on the pattern signal of the signal generation circuit 140, and then generates histogram data D1 (i.e., a compressed histogram) using the pixel signals of each of the multiple pixels P and stores it in memory (for example, the internal memory of the arithmetic circuit 130).

[0101] Based on the histogram data D1 for each subframe stored in the memory, the arithmetic circuit 130 reconstructs histogram data D2 for each pixel P. Furthermore, the arithmetic circuit 130 can calculate a distance value for each pixel P by using the histogram data D2.

[0102] As described above, this embodiment is provided with a selection circuit 121 that can select and output a portion of the pixel signals of each of the plurality of pixels for each period, and with a plurality of conversion circuits 125. It is possible to generate and reconstruct a histogram using the pixel signals converted by each conversion circuit 125. This makes it possible to reduce the circuit area of ​​the photodetector 1 compared to when one TDC is provided for one pixel P.

[0103] In the photodetection device 1, for example, it is possible to reconstruct N histograms using M compressed histograms, which is less than the number of pixels N, and obtain distance information for N pixels. Compressed sensing processing makes it possible to achieve multiple ranging points.

[0104] Furthermore, in this embodiment, the control unit 220 is configured to be able to execute control to selectively cause some of the plurality of light-emitting elements L to emit light. The selection circuit 121 is configured to be able to select and output pixel signals of pixels P corresponding to the light-emitting elements L to be caused to emit light. By performing selective control of the light-emitting elements L, it is possible to reduce the power consumption of the light-emitting device 2. In this embodiment, it is possible to reduce the circuit area and power consumption.

[0105] [Actions and Effects] The photodetector according to this embodiment includes a plurality of pixels (pixels P), each having a light-receiving element (light-receiving element 10) capable of receiving light and outputting a current, and capable of outputting a first signal based on the current of the light-receiving element, a selection circuit (selection circuit 121) capable of selecting and outputting a portion of the first signals of each of the plurality of pixels for each period, and a plurality of conversion circuits (conversion circuits 125) capable of converting the first signal input via the selection circuit into a second signal, which is a digital signal.

[0106] The photodetector 1 according to this embodiment includes a selection circuit 121 that can select and output a portion of the signals Sp1 of the plurality of pixels P for each period, and a plurality of conversion circuits 125 that can convert the signals Sp1 input via the selection circuit 121 into digital signals Sp2. By configuring the photodetector 1 in this manner, it is possible to reduce the number of conversion circuits 125 required for the photodetector 1 and reduce the circuit area. It is possible to realize a photodetector that can reduce the circuit area.

[0107] The light detection system according to this embodiment includes a plurality of light-emitting elements (light-emitting elements L), a control circuit (control unit 220) capable of controlling the plurality of light-emitting elements, a plurality of pixels (pixels P) each having a light-receiving element and capable of outputting a first signal based on the current of the light-receiving element, a selection circuit (selection circuit 121) capable of selecting and outputting a portion of the first signals of each of the plurality of pixels for each period, and a plurality of conversion circuits (conversion circuits 125) capable of converting the first signal input via the selection circuit into a second signal, which is a digital signal.

[0108] The photodetection system 300 according to this embodiment includes a selection circuit 121 that can select and output a portion of the signals Sp1 of the plurality of pixels P for each period, and a plurality of conversion circuits 125 that can convert the signals Sp1 input via the selection circuit 121 into digital signals Sp2. This makes it possible to realize a photodetection system that can reduce the circuit area.

[0109] In the light detection system 300 according to this embodiment, the control circuit (control unit 220) can execute control to selectively cause some of the plurality of light-emitting elements L to emit light. This reduces the power consumption of the light-emitting device 2. It is possible to realize a light detection system capable of reducing power consumption.

[0110] Next, a modified example of the present disclosure will be described. In the following, the same components as those in the above embodiment will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0111] 2. Modifications In the above-described embodiment, exemplary configurations of the light detection system 300, the light detection device 1, and the light emitting device 2 have been described, but the configurations of the light detection system 300, etc. are not limited to the above-described examples. The technology according to the present disclosure is applicable to, for example, cases where flood light is used and cases where spot light is used.

[0112] 12 is a diagram illustrating an example of the configuration of a light detection system according to a modification of the present disclosure. The control unit 220 of the light-emitting device 2 may, for example, perform control to cause some of the light-emitting elements L belonging to a BANK (BANK1 to BANKN in FIG. 12 ) indicating an arrangement area (or group of elements) of elements to emit light one by one, as in the example shown in FIG.

[0113] As shown in the example of Fig. 12, the selection circuit 121 of the photodetector 1 may be configured to selectively output pixel signals of pixels P corresponding to light-emitting elements L among a plurality of pixels P in a bank. For example, the control unit 220 and the selection circuit 121 may perform selection control of light-emitting elements L and pixels P in order from bank 1 to bank N in one subframe. In this modified example, it is also possible to generate and reconstruct histograms. As in the above-described embodiment, it is possible to reduce the circuit area and power consumption.

[0114] 3. Usage Examples The above-described light detection device 1 and light detection system 300 can be used in various cases for sensing light such as visible light, infrared light, ultraviolet light, and X-rays, for example, as described below.・Devices for taking images for viewing purposes, such as digital cameras and mobile devices with camera functions. ・Devices for traffic purposes, such as in-vehicle sensors that take images of the front, rear, surroundings, and interior of a car for safe driving such as automatic stopping, and for recognizing the driver's state, surveillance cameras that monitor moving vehicles and roads, and distance measuring sensors that measure distances between vehicles. ・Devices for home appliances such as televisions, refrigerators, and air conditioners that take images of user gestures and operate the device according to those gestures. ・Devices for medical and healthcare purposes, such as endoscopes and devices that take images of blood vessels by receiving infrared light. ・Devices for security purposes, such as surveillance cameras for crime prevention and cameras for person authentication. ・Devices for beauty purposes, such as skin measuring devices that take images of the skin and microscopes that take images of the scalp. ・Devices for sports purposes, such as action cameras and wearable cameras for sports, etc. ・Devices for agricultural purposes, such as cameras to monitor the condition of fields and crops.

[0115] 4. Application Examples (Application Examples to Mobile Bodies) The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0116] FIG. 13 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.

[0117] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 13, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0118] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0119] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0120] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0121] 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 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0122] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0123] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0124] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0125] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0126] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 13, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0127] FIG. 14 is a diagram showing an example of the installation position of the imaging unit 12031.

[0128] In FIG. 14 , the vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as the imaging unit 12031.

[0129] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The forward images acquired by the imaging units 12101 and 12105 are mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0130] 14 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0131] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0132] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which runs autonomously without relying on driver operation.

[0133] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0134] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0135] An example of a mobile object control system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to, for example, the image capturing unit 12031 of the above-described configuration. Specifically, for example, the light detection device 1 can be applied to the image capturing unit 12031. By applying the technology according to the present disclosure to the image capturing unit 12031, a high-resolution captured image can be obtained, and high-precision control using the captured image can be performed in the mobile object control system.

[0136] Although the present disclosure has been described above by giving embodiments, modifications, use examples, and application examples, the present technology is not limited to the above-described embodiments, etc., and various modifications are possible. For example, although the modifications described above have been described as modifications of the above-described embodiments, the configurations of the modifications can be combined as appropriate.

[0137] According to an embodiment of the present disclosure, a photodetector includes a plurality of pixels each having a light-receiving element capable of receiving light and outputting a current, and capable of outputting a first signal based on the current of the light-receiving element, a selection circuit capable of selecting and outputting a portion of the first signals of each of the plurality of pixels for each period, and a plurality of conversion circuits capable of converting the first signals input via the selection circuit into second signals that are digital signals. This makes it possible to realize a photodetector that can reduce the circuit area.

[0138] Note that the effects described in this specification are merely examples and are not limited to those described above, and other effects may be present. The present disclosure may also have the following configurations: (1) A photodetector comprising: a plurality of pixels, each having a light-receiving element capable of receiving light and outputting a current, and capable of outputting a first signal based on the current of the light-receiving element; a selection circuit capable of selecting and outputting a portion of the first signals of each of the plurality of pixels for each period; and a plurality of conversion circuits capable of converting the first signal input via the selection circuit into a second signal, which is a digital signal. (2) The photodetector described in (1), further comprising an arithmetic circuit capable of generating data related to the light-receiving timing for each pixel based on the plurality of second signals converted for each period by the plurality of conversion circuits. (3) The photodetector described in (1) or (2), wherein the number of conversion circuits is smaller than the number of pixels. (4) The photodetector described in any one of (1) to (3), wherein the conversion circuit is capable of converting the first signal into the second signal related to the light-receiving timing at the pixel. (5) The photodetector according to any one of (1) to (4), wherein the conversion circuit is a TDC (Time to Digital Converter). (6) The photodetector according to any one of (1) to (5), wherein the selection circuit is capable of selecting and outputting a portion of the first signals of each of the plurality of pixels in a first period and selecting and outputting another portion of the first signals of each of the plurality of pixels in a second period. (7) The photodetector according to any one of (1) to (6), wherein the selection circuit is capable of selecting and outputting a portion of the first signals of each of the plurality of pixels based on a random number or a pseudo-random number. (8) The photodetector according to any one of (1) to (7), further comprising a first generation circuit capable of generating first data by adding the second signals converted by the plurality of conversion circuits, wherein the first generation circuit is capable of generating the first data for each of the periods. (9) The photodetector according to (8), further comprising: a second generation circuit capable of generating second data relating to a light receiving timing for each pixel based on the first data for each period.(10) The photodetector device according to any one of (1) to (9), wherein the light-receiving element is an avalanche photodiode. (11) A photodetection system comprising: a plurality of light-emitting elements; a control circuit capable of controlling the plurality of light-emitting elements; a plurality of pixels each having a light-receiving element and capable of outputting a first signal based on a current of the light-receiving element; a selection circuit capable of selecting and outputting a portion of the first signals of each of the plurality of pixels for each period; and a plurality of conversion circuits capable of converting the first signal input via the selection circuit into a second signal, which is a digital signal. (12) The photodetection system according to (11), wherein the control circuit is capable of executing control to selectively emit light from a portion of the plurality of light-emitting elements. (13) The photodetection system according to (11) or (12), wherein the selection circuit is capable of outputting the first signal of a pixel of the plurality of pixels corresponding to the light-emitting element to be emitted. (14) The photodetection system according to any one of (11) to (13), wherein the control circuit is capable of executing control to selectively cause some of the plurality of light-emitting elements to emit light in a first period and selectively cause other some of the plurality of light-emitting elements to emit light in a second period, and the selection circuit is capable of selecting and outputting some of the first signals of each of the plurality of pixels in the first period and selecting and outputting other some of the first signals of each of the plurality of pixels in the second period. (15) The photodetection system according to any one of (11) to (14), wherein the control circuit is capable of executing control to selectively cause some of the plurality of light-emitting elements to emit light based on a pseudo-random number, and the selection circuit is capable of selectively outputting some of the first signals of each of the plurality of pixels based on the pseudo-random number. (16) The photodetection system according to any one of (11) to (15), further comprising an arithmetic circuit capable of generating data regarding light-receiving timing for each of the pixels, based on the plurality of second signals for each of the periods converted by the plurality of conversion circuits. (17) The light detection system according to any one of (11) to (16), wherein the number of the conversion circuits is smaller than the number of the pixels.(18) The photodetection system according to any one of (11) to (17), wherein the conversion circuit is capable of converting the first signal into the second signal related to light reception timing at the pixel. (19) The photodetection system according to any one of (11) to (18), further comprising a first generation circuit capable of generating first data by adding together the second signals converted by the conversion circuits, wherein the first generation circuit is capable of generating the first data for each period. (20) The photodetection system according to (19), further comprising a second generation circuit capable of generating second data related to light reception timing for each pixel based on the first data for each period.

[0139] This application claims priority based on Japanese Patent Application No. 2024-112169, filed on July 12, 2024, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0140] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and are intended to be within the scope of the appended claims and their equivalents.

Claims

1. A photodetector device comprising: a plurality of pixels, each having a light-receiving element capable of receiving light and outputting a current, and capable of outputting a first signal based on the current of the light-receiving element; a selection circuit capable of selecting and outputting a portion of the first signals of each of the plurality of pixels for each period; and a plurality of conversion circuits capable of converting the first signals input via the selection circuit into second signals, which are digital signals.

2. The photodetector according to claim 1, further comprising an arithmetic circuit capable of generating data relating to the light receiving timing for each pixel based on the second signals converted by the conversion circuits for each period.

3. The photodetector device according to claim 1, wherein the number of said conversion circuits is less than the number of said pixels.

4. The photodetector according to claim 1, wherein the conversion circuit is capable of converting the first signal into the second signal related to the timing of light reception at the pixel.

5. The photodetector according to claim 1, wherein the conversion circuit is a TDC (Time to Digital Converter).

6. The photodetector device according to claim 1, wherein the selection circuit is capable of selecting and outputting a portion of the first signals of each of the plurality of pixels during a first period, and selecting and outputting another portion of the first signals of each of the plurality of pixels during a second period.

7. The photodetector according to claim 1, wherein the selection circuit is capable of selecting and outputting a portion of the first signals of each of the plurality of pixels based on a random number or a pseudo-random number.

8. The photodetector according to claim 1, further comprising a first generation circuit capable of generating first data by adding together the second signals converted by the conversion circuits, wherein the first generation circuit is capable of generating the first data for each of the periods.

9. The photodetector according to claim 8, further comprising a second generation circuit capable of generating second data relating to the light receiving timing for each pixel based on the first data for each period.

10. The photodetector according to claim 1, wherein the light receiving element is an avalanche photodiode.

11. A light detection system comprising: a plurality of light-emitting elements; a control circuit capable of controlling the plurality of light-emitting elements; a plurality of pixels each having a light-receiving element and capable of outputting a first signal based on the current of the light-receiving element; a selection circuit capable of selecting and outputting a portion of the first signals of each of the plurality of pixels for each period; and a plurality of conversion circuits capable of converting the first signals input via the selection circuit into second signals which are digital signals.

12. The light detection system according to claim 11, wherein the control circuit is capable of executing control to selectively cause some of the plurality of light-emitting elements to emit light.

13. The light detection system according to claim 11, wherein the selection circuit is capable of outputting the first signal of the pixel among the plurality of pixels that corresponds to the light emitting element to be caused to emit light.

14. The light detection system described in claim 11, wherein the control circuit is capable of executing control to selectively cause some of the plurality of light-emitting elements to emit light in a first period and selectively cause other some of the plurality of light-emitting elements to emit light in a second period, and the selection circuit is capable of selecting and outputting some of the first signals of each of the plurality of pixels in the first period and selecting and outputting other some of the first signals of each of the plurality of pixels in the second period.

15. The light detection system of claim 11, wherein the control circuit is capable of executing control to selectively cause some of the plurality of light-emitting elements to emit light based on a pseudo-random number, and the selection circuit is capable of selectively outputting some of the first signals of each of the plurality of pixels based on the pseudo-random number.

16. The light detection system according to claim 11, further comprising an arithmetic circuit capable of generating data relating to the light receiving timing for each pixel based on the second signals converted for each period by the conversion circuits.

17. The optical detection system according to claim 11, wherein the number of said conversion circuits is less than the number of said pixels.

18. The light detection system according to claim 11, wherein the conversion circuit is capable of converting the first signal into the second signal related to the timing of light reception at the pixel.

19. The optical detection system according to claim 11, further comprising a first generation circuit capable of generating first data by adding together the second signals converted by the conversion circuits, wherein the first generation circuit is capable of generating the first data for each of the periods.

20. The light detection system according to claim 19, further comprising a second generation circuit capable of generating second data relating to the light receiving timing for each pixel based on the first data for each period.

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