Light receiving device, distance measuring device and light receiving circuit

Abstract

[Problem] Provided is a light receiving device, a light receiving circuit, and a distance measuring device capable of detecting photons with high accuracy regardless of the illumination in the environment. [Solution] According to the present disclosure, a light receiving device includes: a first light receiving circuit configured so that a recharging method of a light receiving element can be switched; and a control circuit configured to control the recharging method of the first light receiving circuit based on a signal output by the first light receiving circuit as a result of an action with a photon.

Description

Technical Field

[0001] The present disclosure relates to a light receiving device, a distance measuring device and a light receiving circuit. Background Art

[0002] In multiple fields such as vehicle-mounted and mobile, the application of technology for measuring the distance to an object based on the time of flight (TOF) in which the irradiated light from a light-emitting element is reflected by the object and returns to a light-receiving element is progressing. Avalanche photodiodes (APDs) are known light-receiving elements. In a Geiger-mode APD, a voltage greater than or equal to a breakdown voltage is applied between two terminals, and an avalanche phenomenon occurs with the incidence of a single photon. An APD in which a single photon causes multiplication by the avalanche phenomenon is called a single-photon avalanche diode (SPAD).

[0003] In a SPAD, the avalanche phenomenon can be stopped by reducing the voltage between the two terminals to the breakdown voltage. Stopping the avalanche phenomenon by reducing the voltage between the terminals is called quenching. When the voltage between the two terminals of the SPAD is recharged to a bias voltage greater than or equal to the breakdown voltage, photons can be detected again.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Publication No. 2010-091377

[0007] Patent Document 2: Japanese Patent Publication No. 2014-081254

[0008] Patent Document 2: Japanese Patent Publication No. 2018-179732 Summary of the invention

[0009] Technical Problems to be Solved by the Invention

[0010] The measurement distance according to TOF requires a device that supports a dynamic range for a wide brightness range. However, in an environment with high illumination, there are situations where the SPAD recharging may stop, or the SPAD takes a long time to recharge. Therefore, the dead time (dead time) in which photon detection cannot be performed becomes longer. It is desirable to shorten the dead time in order to perform distance measurement with high accuracy.

[0011] Therefore, the present disclosure provides a light receiving device, a light receiving circuit, and a distance measuring device that can detect photons with high accuracy regardless of the illumination in the environment.

[0012] Solution to the problem

[0013] According to one aspect of the present disclosure, a light receiving device may include: a first light receiving circuit configured to enable switching of a recharging method for a light receiving element; and a control circuit configured to control the recharging method for the first light receiving circuit based on a signal output by the first light receiving circuit through a reaction with photons.

[0014] The recharging method may include at least one of passive recharging, active recharging, and a combination of passive recharging and active recharging.

[0015] The recharging method may include at least one of a recharging current for a passive recharging operation, and a time delay for generating a reset pulse for an active recharging operation.

[0016] A plurality of first light receiving circuits may be provided, and the control circuit is configured to control a recharging method for at least one first light receiving circuit based on signals output from the plurality of first light receiving circuits.

[0017] A measurement circuit may also be provided, the measurement circuit being configured to count the number of reactions in the plurality of first light receiving circuits, and the control circuit being configured to control a recharging method for at least one first light receiving circuit based on the number of reactions.

[0018] An error detector may also be provided, the error detector being configured to perform error determination based on the waveform of the signal output by the first light receiving circuit, and the control circuit being configured to control a recharging method for at least one first light receiving circuit based on the number of error determinations of the signals output by the plurality of first light receiving circuits.

[0019] The error detector may be configured to perform error determination on at least one of a signal having a pulse width exceeding a first threshold and a signal having an interval between pulses less than a second threshold.

[0020] An error correction circuit configured to perform error determination based on a waveform of a signal output by the first light receiving circuit and correct the waveform of the signal on which the error determination is performed may also be provided.

[0021] The error correction circuit may be configured to perform error determination on at least one of a signal having a pulse width exceeding a first threshold and a signal having an interval between pulses less than a second threshold.

[0022] The control circuit may be configured to control a recharging method used in at least one first light receiving circuit based on a number of erroneous determinations of signals output from the plurality of first light receiving circuits.

[0023] The control circuit may be configured to control a recharging method for the first light receiving circuit for each region of the captured image.

[0024] The control circuit may be configured to control a recharging method for the plurality of first light receiving circuits based on a signal output by the first light receiving circuit corresponding to a partial area of ​​the captured image.

[0025] A plurality of second light receiving circuits configured to perform a passive recharging operation may also be provided.

[0026] The first light receiving circuit may be connected to the first pixel, and each second light receiving circuit may be connected to a second pixel having a light receiving surface or an opening surface smaller than that of the first pixel.

[0027] The light receiving element may be an avalanche photodiode.

[0028] According to one aspect of the present disclosure, a ranging device may include: a light-emitting element; a plurality of light-receiving circuits configured to switch a recharging method for the light-receiving element; and a control circuit configured to control a recharging method for at least one light-receiving circuit based on a signal output by the plurality of light-receiving circuits through a reaction with photons during a period when the light-emitting element does not emit light.

[0029] According to one aspect of the present disclosure, a light receiving circuit may include: a light receiving element, a load element connected to a reference potential, a first switch connected between the load element and the light receiving element, an inverter connected to a first signal line between the first switch and the light receiving element via a second signal line, a first transistor connected to the reference potential, a second switch connected between the first transistor and the second signal line, and a pulse generator connected to a third signal line as a post-stage of the inverter and a first control electrode of the first transistor.

[0030] The pulse generator may be configured to output a pulse to the first control electrode according to a voltage of the third signal line.

[0031] The pulse generator may be configured to output a pulse to the first control electrode with a time delay when a voltage level of the third signal line changes.

[0032] A second transistor connected to the reference potential and a third switch connected between the second transistor and the second signal line are also provided, and a second control electrode of the second transistor is connected to the third signal line. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a block diagram illustrating an example of a distance measuring device.

[0034] Figure 2 is a view schematically illustrating an example of distance measurement by using a distance measuring device.

[0035] Figure 3 is a circuit diagram showing an example of a light receiving circuit.

[0036] Figure 4 is a graph showing an example of a voltage waveform in a light receiving circuit.

[0037] Figure 5 is a graph showing an example of a histogram in a low illumination environment.

[0038] Figure 6 is a graph showing an example of a histogram in a high illumination environment.

[0039] Figure 7 is a graph showing an example of an ideal histogram in a high illumination environment.

[0040] Figure 8 is a view schematically showing an example of a light receiving device according to the present disclosure.

[0041] Fig. 9 is a circuit diagram illustrating an example of a circuit according to the present disclosure.

[0042] Fig.10 is a table indicating examples of switch settings for circuits according to the present disclosure.

[0043] Fig.11 is a graph showing an example of a voltage waveform in a circuit according to the present disclosure.

[0044] Fig.12 is a circuit diagram showing a configuration example of a pulse generator.

[0045] Fig.13 is a graph showing an example of the relationship between the number of SPADs that react and the threshold value.

[0046] Fig.14 : is a table showing an example of the correspondence between the number of SPADs that react and the selected operation mode.

[0047] Fig.15 is a flowchart showing an example of a process for determining distance measurement conditions.

[0048] Fig.16 is a plan view showing an example of the correspondence relationship between pixels and recharging circuits.

[0049] Fig.17 is a plan view showing an example of the correspondence relationship between pixels and recharging circuits.

[0050] Fig.18 is a view showing an example of setting distance measurement conditions for a region of each image.

[0051] Fig.19 is a view showing an example of setting distance measurement conditions for each image.

[0052] Fig. 20 is a block diagram illustrating an example of a light receiving device.

[0053] Fig.21 : is a schematic diagram showing an example of a light receiving device according to a first modification.

[0054] Fig. 22 is a graph illustrating an example of erroneous detection of a voltage waveform.

[0055] Fig.23 is a table indicating examples of operation modes in the first modification.

[0056] Fig.24 is a flowchart illustrating an example of a process for determining a distance measurement condition according to the first modification example.

[0057] Fig.25 : is a schematic diagram showing an example of a light receiving device according to a second modification.

[0058] Fig.26 is a graph showing an example of a process for correcting a voltage waveform in the second modification.

[0059] Fig. 27 is a graph showing an example of a process for correcting a voltage waveform in the second modification.

[0060] Fig.28 is a circuit diagram showing an example of a circuit according to a third modification example.

[0061] Fig.29 is a circuit diagram illustrating an example of an active recharging circuit.

[0062] Fig.30 is a block diagram illustrating an example of a distance measuring device.

[0063] Fig.31 is a block diagram depicting an example of a schematic configuration of a vehicle control system.

[0064] Fig.32 2 is a diagram to help explain an example of the installation positions of the external vehicle information detection section and the imaging section. DETAILED DESCRIPTION

[0065] With reference to the accompanying drawings, a description is given below in detail about suitable embodiments according to the present disclosure. Note that in this specification and the accompanying drawings, the same reference numerals are added to components having substantially the same functional configuration, thereby omitting repeated descriptions.

[0066] Figure 1The block diagram in FIG. 1 shows an example of a distance measuring device. Figure 2 An example of distance measurement by using a distance measuring device is schematically shown. Figure 1 The distance measuring device 200 in the embodiment includes a communication circuit 210, a control circuit 220, a SPAD controller 221, a circuit block 240, a circuit block 241, a processing circuit 230, a transmission circuit 211, a PLL 250, a clock generator 251, a current source 252, a temperature sensor 253, and a trigger circuit 254. The processing circuit 230 includes a histogram generator 232 and a distance calculation unit 233 as internal components. In addition, the distance measuring device 200 is connected to the transmission circuit 211 via the terminal T_OUT. Figure 2 The light emitting element 255 is included in the embodiment of the present invention.

[0067] The communication circuit 210 and the transmission circuit 211 communicate with the external circuit. The control circuit 220 controls each component of the distance measuring device 200. The circuit block 240 corresponds to Figure 2 Detection unit 1 in. Circuit block 240 is equipped with, for example, a SPAD array and a light receiving circuit corresponding to each SPAD. The SPAD array includes a plurality of single photon avalanche diodes (SPADs). Each light receiving circuit is configured to output a pulse to a subsequent circuit when the SPAD reacts with a photon. In addition, the light receiving circuit includes a circuit for quenching the SPAD and recharging the SPAD. The SPAD controller 221 controls the light receiving circuit. For example, the SPAD controller 221 switches a switch in the light receiving circuit, controls a current value, and controls the timing of pulse generation.

[0068] For example, the circuit block 241 includes a sampler connected as a subsequent stage of the corresponding light receiving circuit. Each sampler is called a buffer and digitizes the signal input from the light receiving circuit. In addition, the circuit block 241 may include an error detector or an error correction circuit. The details of the error detector and the error correction circuit are described below. The trigger circuit 254 controls the light emission timing of the light emitting element 255.

[0069] The histogram generator 232 samples the voltage level of the digitized output signal from each light receiving circuit and generates a histogram. The histogram generator 232 can repeat the sampling operation multiple times and generate a histogram. The sampling operation is performed multiple times, so that the interference light and the reflected light rl of the light irradiated from the light emitting element can be identified. When generating a histogram, the histogram generator 232 can perform calculations such as the average value of multiple measurement results. The distance calculation unit 233 calculates the distance between the distance measuring device 200 and the object based on information related to the irradiation time t0 of the light transmitted from the trigger circuit 254 and the peak time t1 of the histogram. For example, assuming that the speed of light is C, the distance between the distance measuring device 200 and the object OBJ can be obtained by the formula L=c / 2(t1-t0). In the formula, t1-t0 corresponds to the flight time. By using the transmission circuit 211, information including the calculated distance can be transmitted to an external circuit.

[0070] For example, according to a hardware circuit such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), the components of the processing circuit 230, including the histogram generator 232 and the distance calculation unit 233, can be implemented. However, the functions of the processing circuit 230 can be implemented by a central processing unit (CPU) and a program executed by the CPU. In this case, the processing circuit 230 may include a memory or storage device for storing the program and data required for executing the program.

[0071] Notice, Figure 1 The distance measuring device 200 in FIG. 1 is only an example of the configuration of the distance measuring device. Therefore, the configuration of the distance measuring device according to the present disclosure may be different from the configuration of the distance measuring device 200. The distance measuring device does not need to include all the components of the distance measuring device 200. For example, the distance measuring device may omit at least one of the PLL 250, the clock generator 251, the current source 252, the temperature sensor 253, the trigger circuit 254, and the communication circuit 210. In addition, other components may be added, or these other components may be omitted.

[0072] Figure 3 The circuit diagram in shows an example of a light receiving circuit used in photon detection. In addition, Figure 4 The graph in shows an example of a voltage waveform in a light receiving circuit. Figure 3The circuit 13 in includes a photodiode PD, a transistor TR0 and an inverter INV. The transistor TR0 is a PMOS transistor. For example, a SPAD can be used as the photodiode PD. The source of the transistor TR0 is connected to the power supply potential Vdd. The drain of the transistor TR0 is connected to the cathode of the photodiode PD. The voltage Van is applied to the anode of the photodiode PD. Through the voltage Van, a reverse voltage greater than or equal to the breakdown voltage is applied between the two terminals of the photodiode PD. The drain of the transistor TR0 and the cathode of the photodiode PD are connected to the input side of the inverter INV. In addition, a post-stage circuit such as a buffer is connected to the output side of the inverter INV.

[0073] The transistor TR0 is an example of the load element 90 of the circuit 13. However, the configuration of the load element may be different therefrom. For example, as the load element, a resistor may be used, or a result of combining a transistor and a resistor may be used.

[0074] When a photon is incident on the photodiode PD and the current between the two terminals of the photodiode PD increases due to avalanche multiplication, the cathode potential Vca decreases according to the voltage drop at the load element 90. When the voltage between the terminals of the photodiode PD is reduced to the breakdown voltage, the avalanche phenomenon stops, and the current flowing between the two terminals of the photodiode PD is reduced. As a result, the voltage between the two terminals of the photodiode PD takes a value greater than or equal to the breakdown voltage, and the photon can be detected again (Vca in the graph 60). In contrast, the inverter INV outputs a positive polarity (HIGH) pulse (Vp in the graph 60) during a period in which the cathode potential Vca is less than or equal to the threshold value thi. When a photon is detected, the circuit 13 outputs a pulse, so that various processes such as counting photons, generating a histogram, and calculating the flight time can be performed in the subsequent circuit.

[0075] Note that a circuit for performing the operation shown in the graph 60 is referred to as a passive recharging circuit. The above-described circuit 13 is an example of a passive recharging circuit. As a passive recharging circuit, a circuit having a configuration different from that of the circuit 13 may be used. For example, a circuit produced by reversing the polarity may be used. In addition, a circuit produced by adding another element to the circuit 13 may be used. When a passive recharging circuit is used, power consumption can be suppressed.

[0076] After the photodiode PD reacts with the photon, the photodiode PD cannot detect the photon during the period of stopping the avalanche phenomenon (quenching) and recharging the voltage between the two terminals of the photodiode PD to a value greater than or equal to the breakdown voltage. This period is called the dead time. Increasing the number of SPADs installed in the device can reduce the impact of the dead time. This is because, if there are a sufficient number of SPADs, other SPADs can compensate for the detection capabilities of some SPADs that have entered the dead time.

[0077] In the passive recharging circuit, the recharging current flowing through the load element 90 is increased, so that the dead time can be shortened to a certain level. However, when the recharging current increases too much, the voltage between the terminals of the photodiode PD stops decreasing to the breakdown voltage, and thus the photodiode PD cannot perform quenching (Vca in the graph 62). At this time, since the output voltage of the inverter INV is stuck, it is difficult to detect photons.

[0078] In addition, in a high illumination environment, before the cathode potential Vca rises above the threshold of the inverter INV, the photodiode PD may re-react with the photons from the interfering light. Therefore, there is a delay in the rise of the cathode potential Vca, and the dead time is extended. In addition, the pulse width output by the inverter INV becomes too large (curve 61). When the pulse width becomes too large, the processing such as distance measurement performed by the subsequent circuit may become difficult.

[0079] Next, a description is given of an example of a histogram generated by the histogram generator.

[0080] Figure 5 The graph in shows an example of a histogram generated in a low-light environment. Figure 6 The graphs in FIG. 1 show examples of histograms generated in a high illumination environment. In each graph, the vertical axis indicates the number of SPADs that react. In addition, the horizontal axis indicates the time difference from the light emission time of the light emitting element 255. When the illumination of the interfering light is low, a histogram with a clear peak corresponding to the reflected light rl can be generated ( Figure 5 ). However, in a high illumination environment, SPAD is more likely to react to photons from interfering light rather than photons from reflected light rl. Figure 4 As shown in , there is a tendency for the dead time of SPADs to increase in high illumination environments. Therefore, since the number of SPADs that cannot react to photons increases, clear peaks will stop appearing in the histogram ( Figure 6 ). Ideally, even in high illumination environments, it is desirable to be able to generate Figure 5 The histogram in is shifted upwards to correspond to the number of photons of the interfering light, as shown in Figure 7As shown in the curve graph.

[0081] It is envisioned that photon detection by SPADs is performed in various illumination environments, such as outdoors on a clear day, at night, or in a tunnel. In order to perform high-precision distance measurement independent of the illumination of the environment, it is necessary to have a technology for high-precision detection of photons in a dynamic range of a wide brightness range.

[0082] A description is given below about a light receiving circuit and a light receiving device according to the present disclosure.

[0083] Figure 8 An example of a light receiving device according to the present disclosure is schematically shown. Figure 8 The optical receiving device 100 in the embodiment includes a plurality of optical receiving circuits 11, a plurality of samplers 20, a measuring circuit 30 and a control circuit 40. The optical receiving circuit 11 includes a SPAD and an optical receiving circuit. The measuring circuit 30 includes a histogram generator 31 as an internal component.

[0084] The plurality of light receiving circuits 11 are provided in, for example, a circuit block 240 ( Figure 1 ). For example, a plurality of samplers 20 are provided in the circuit block 241. The measurement circuit 30 corresponds to the processing circuit 230. For example, the control circuit 40 corresponds to the control circuit 220 and the SPAD controller 221.

[0085] Each light receiving circuit 11 is connected to the subsequent stage sampler 20 via a signal line l_rd. The subsequent stage of each sampler 20 is connected to a measurement circuit 30. The measurement circuit 30 is connected to a control circuit 40. The control circuit 40 is connected to each light receiving circuit 11 via a signal line l_ct. Figure 8 In FIG. 4 , a plurality of signal lines l_ct are shown, but the number of signal lines used for control is not important. For example, the control circuit 40 can control a plurality of light receiving circuits 11 through one signal line.

[0086] When the SPAD reacts to the photon, the light receiving circuit 11 outputs a pulse to the signal line l_rd. The sampler 20 digitizes the signal including the pulse. The histogram generator 31 generates a histogram based on the pulse included in the signal input from each sampler.

[0087] Fig. 9 The circuit diagram in shows an example of a circuit according to the present disclosure. Fig. 9 The circuit 10 in FIG. 1 includes a photodiode PD, a switch SW1, a transistor TR0, a transistor TR1, a switch SW2, a transistor TR2, a switch SW3, an inverter INV, and a pulse generator PG. The transistor TR0, the transistor TR1, and the transistor TR2 are all PMOS transistors. For example, a SPAD can be used as the photodiode PD.

[0088] For example, the switch SW1, the switch SW2, and the switch SW3 are implemented by MOS transistors. For example, the gate of each MOS transistor may be connected to the control circuit 40. In this case, the control circuit 40 turns on / off the switch by controlling the voltage applied to the gate of each MOS transistor. Note that the gate of the transistor TR0 may be connected to the control circuit 40. In this case, the control circuit 40 may control the voltage applied to the gate of the transistor TR0 and adjust the resistance between the source and drain of the transistor TR0.

[0089] The source of transistor TR0 is connected to the power supply potential Vdd. Switch SW1 is connected between the drain of transistor TR0 and the cathode of photodiode PD. Voltage Van is applied to the anode of photodiode PD. The value of voltage Van can be determined so that a reverse voltage greater than or equal to the breakdown voltage is applied between the two terminals of photodiode PD. The input terminal of inverter INV is connected to the cathode of photodiode PD and switch SW1 via signal line Lin.

[0090] The source of transistor TR1 and the source of transistor TR2 are both connected to the power supply potential Vdd. Switch SW2 is connected between the drain of transistor TR1 and the signal line Lin. At the same time, switch SW3 is connected between the drain of transistor TR2 and the signal line Lin. The output terminal of inverter INV is connected to the gate of transistor TR2 and the input terminal of pulse generator PG via signal line Lout. The output terminal of pulse generator PG is connected to the gate of transistor TR1.

[0091] Fig.10 The table in indicates examples of switch settings for circuit 10. Fig.10 As shown in Table 70 in FIG. 1 , in the circuit 10, the method of recharging the photodiode PD can be switched according to the switch setting. When the switch SW1 is turned off and the switches SW2 and SW3 are turned on, the circuit 10 can be made to perform active recharging (switch setting st1). This is used to Fig. 9 The switch setting for active recharging is shown in the circuit 10. When the switch SW1 is turned on and the switches SW2 and SW3 are turned off, the circuit 10 can be made to perform passive recharging (switch setting st2). In this case, the circuit 10 performs the same as Figure 3 The circuit 10 can be operated similarly to the operation of the circuit 13 (passive recharging circuit) in FIG. 1. In addition, when the switch SW1 and the switch SW2 are turned on, the circuit 10 can be made to perform both active recharging and passive recharging (switch setting st3). In this case, the switch SW3 can be turned on or off.

[0092] Fig.11 The graph in shows an example of voltage waveforms in the circuit 10. Fig.11 Graph 63 in FIG. 6 corresponds to a voltage waveform in the case where passive recharging is performed in the circuit 10. In contrast, graph 64 corresponds to a voltage waveform in the case where active recharging is performed in the circuit 10. Note that Vg in graph 64 indicates the gate voltage of transistor TR1. In all graphs, the horizontal axis indicates time.

[0093] A description is given of the operation when active recharging is caused in the circuit 10 (when the switch is set st1). When photons are incident on the photodiode PD and the current flowing between the two terminals of the photodiode PD increases due to avalanche multiplication, the cathode potential Vca decreases according to the voltage drop between the source and drain of the transistor TR1 and the transistor TR2. The avalanche phenomenon stops (quenches) when the voltage between the two terminals of the photodiode PD decreases to the breakdown voltage, which is similar to the case of performing passive recharging.

[0094] The inverter INV outputs a HIGH (positive polarity) pulse (Vp in the graph 64) during a period when the voltage of the signal line Lin is less than or equal to the threshold value thi. Based on this pulse, the post-stage measurement circuit 30 can perform various processes. Because the voltage of the signal line Lin is negative polarity (LOW), the voltage of the signal line Lout on the output side of the inverter INV becomes HIGH. When a HIGH signal is input to the pulse generator PG, a LOW (negative polarity) pulse is output after a time delay td. Therefore, a LOW voltage is applied to the gate of the transistor TR1 and is turned on between the source and drain of the transistor TR1. At Vg in the graph 64, a LOW pulse is output during the period tr. As a result, the cathode potential Vca is raised by the power supply potential Vdd, and photon detection can be performed again by the photodiode PD.

[0095] When the voltage of the signal line Lin becomes HIGH due to recharging, the voltage of the signal line Lout on the output side of the inverter INV becomes LOW. At this time, the LOW voltage is applied to the gate of the transistor TR2, and conduction occurs between the source and drain of the transistor TR2. In this way, the transistor TR2 latches the state of the transistor TR1. Through the transistor TR2, the occurrence of the through current can be suppressed and the cathode potential Vca can be prevented from becoming infinite.

[0096] Note that in the case where not only switches SW2 and SW3 but also switch SW1 is turned on (switch setting st3), the voltage drop between the source and drain of transistor TR0 also contributes to quenching the photodiode PD. The case where the voltage between the terminals of the photodiode PD rises when the current flowing between the terminals of the photodiode PD decreases due to quenching is similar to Figure 3 The situation of circuit 13 in FIG.

[0097] In the circuit 10, a portion including the transistor TR1, the transistor TR2, the switch SW2, the switch SW3, and the pulse generator PG corresponds to the active recharging circuit 91. In addition, in the circuit 10, a portion including the transistor TR0 (load element 90) and the switch SW1 corresponds to the passive recharging circuit. The circuit 10 is an example of a light receiving circuit that includes a passive recharging circuit and an active recharging circuit and is capable of switching a recharging method.

[0098] Note that it is possible to use circuit 10 ( Fig. 9 ) is a circuit having a configuration different from the configuration of the circuit 10. For example, a circuit generated by adding another element to the circuit 10 may be used. In addition, a circuit generated by reversing the polarity in the circuit 10 may be used. In the case of using a circuit generated by reversing the polarity, the PMOS transistor may be replaced by an NMOS transistor. In addition, when the polarity is reversed in the circuit 10, a positive bias voltage is applied to the cathode of the photodiode PD. Note that a configuration of reversing the polarity may be adopted for other circuits described in this specification, not limited to the circuit 10.

[0099] Fig.12 The circuit diagram in shows an example of the configuration of a pulse generator. Fig.12 The pulse generator PG in includes a trigger FP and an inverter INV2. The trigger FP is a D trigger. The signal line Lout is connected to the D terminal of the trigger F1. The signal line dctr is connected to the clock terminal of the trigger F1. The inverter INV2 is connected between the Q terminal of the trigger F1 and the gate of the transistor TR1.

[0100] exist Fig.12 In the pulse generator PG in the embodiment, by controlling the clock signal provided on the signal line dctr, the time delay td from when the voltage of the signal line Lout changes to the HIGH level until the voltage Vg changes to the LOW level can be changed. For example, when the interval between pulses in the clock signal increases, the time delay td can be increased. In addition, when the interval between pulses in the clock signal decreases, the time delay td can be reduced. If using Fig.12 If the pulse generator PG in the circuit is used, it becomes easy to control the time delay according to the clock signal provided from the outside. For example, the control circuit 40 or the clock generator 251 can provide a clock signal to the signal line dctr.

[0101] Notice, Fig.12The circuit in is only an example of the pulse generator PG. Therefore, a pulse generator having a configuration different from this may be used. For example, the pulse generator may be implemented according to an inverter chain. In addition, the pulse generator may be implemented by combining a delay device and a logic operation element. In other words, as long as a pulse can be output to the gate of the transistor TR1 in a time-delayed manner after the level of the input voltage is changed, a pulse generator having any circuit configuration may be used.

[0102] Next, suppose Fig. 9 The circuit 10 is implemented as Figure 8 A description is given of the operation of the light receiving device according to the present disclosure with reference to each light receiving circuit 11 in FIG.

[0103] Fig.13 The graph in FIG. 1 shows an example of a histogram generated by the light receiving device according to the present disclosure in order to measure interference light. Fig.13 The vertical axis of the graph in corresponds to the number Nr of SPADs that react. At the same time, the horizontal axis of the graph corresponds to the photon detection time. In order to measure the illumination of the environment (interference light), the measurement circuit 30 measures the number of SPADs that react in the light receiving device 100 during the period when the light emitting element does not emit light. In addition, the histogram generator 31 can be used to generate a histogram such as Fig.13 The histogram is shown. Fig.13 The graph in indicates the threshold value th1 and the threshold value th2 by dotted lines.

[0104] The measurement circuit 30 transmits the number Nr of the SPADs that react to the control circuit 40. The control circuit 40 can then compare the number of SPADs that react with the threshold th1 and the threshold th2, and determine the recharging method. In the recharging method, for example, passive recharging, active recharging, and a combination of passive recharging and active recharging are specified. In addition, parameters for recharging operations can be specified in the recharging method. Examples of parameters for recharging operations include the time delay td for generating a pulse for active recharging or the recharging current during passive recharging. However, other types of setting values ​​can be specified in the parameters. In addition, it is not necessary to be able to specify all parameters for recharging operations. For example, in the case of using a circuit with a fixed time delay td for generating a pulse for active recharging or a circuit in which dynamic control of the recharging current is not feasible, these parameters can be excluded from the control object.

[0105] Generally, it is estimated that the number Nr of SPADs reacting is related to the illumination of the environment. Therefore, if the number Nr of SPADs reacting is large, it can be estimated that the light receiving device 100 is installed in an environment with high illumination. In contrast, if the number Nr of SPADs reacting is small, it can be estimated that the light receiving device 100 is installed in an environment with low illumination.

[0106] Fig.14 The table in shows an example of the correspondence between the number of SPADs that react and the selected operation mode. Fig.14 Table 71 in which different operation modes are selected according to the number of SPADs that react. For example, when the number Nr of SPADs that react is greater than or equal to the threshold th2, active recharging (mode m1) is performed. In addition, when the number Nr of SPADs that react is less than the threshold th2, passive recharging is performed. When the number Nr of SPADs that react is greater than the threshold th1 and less than the threshold th2, passive recharging according to the recharging current i1 is performed (mode m2). When the number Nr of SPADs that react is less than or equal to the threshold th1, passive recharging according to the recharging current i2 less than i1 is performed (mode m3).

[0107] Generally, active recharging enables the dead time to be shortened more than passive recharging. Therefore, it can be said that active recharging is a recharging method suitable for high illumination environments. In contrast, passive recharging has the advantage of being able to suppress power consumption more than active recharging. In the case of passive recharging, having a large recharging current enables the dead time to be shortened. Therefore, in the example of Table 71, it is expected that the dead time of the SPAD is shortened in the order of mode m3, mode m2, and mode m1.

[0108] The more the mode that is expected to shorten the dead time, the more power is required. Therefore, it can be said that the dead time and power consumption of the SPAD are in a trade-off relationship. Therefore, as illustrated in Table 71, according to the number Nr of SPADs that react with the illumination of the environment, the best operation mode that achieves a balance between the dead time and the power consumption can be selected. In this way, when a mode that defines a recharging method including parameters is used, the complication of the processing performed by the measurement circuit 30 and the control circuit 40 can be avoided.

[0109] Note that the control circuit 40 may compare the number of SPADs that react obtained in one measurement with a threshold value. In addition, the control circuit 40 may compare a representative value based on the number of SPADs that react obtained in multiple measurements with a threshold value. For example, the control circuit 40 may compare the average value of the number of SPADs that react measured multiple times with a threshold value. In addition, the control circuit 40 may compare the number of SPADs that react with a threshold value each time a measurement is performed, and select an operation mode based on the determination result with the highest frequency.

[0110] The switching of the modes indicated in Table 71 is merely an example of a method for changing the recharging method for the optical receiving circuit 11. The recharging method for the optical receiving circuit may be changed according to a method different from the method of Table 71. For example, active recharging may be selected when the number of reacting SPADs exceeds the threshold value t_rch, and passive recharging may be selected when the number of reacting SPADs is less than or equal to the threshold value t_rch. In the presence of parameters that can be adjusted in the optical receiving circuit 11, the parameters may be determined based on the number Nr of reacting SPADs. For example, a function with the number Nr of reacting SPADs as a variable may be used to determine the pulse delay or the recharging current. In this case, a function may be used in which the value of the pulse delay is smaller when the number Nr of reacting SPADs is larger. In addition, a function may be used in which the value of the recharging current is larger when the number Nr of reacting SPADs is larger.

[0111] Fig.15 The flowchart in FIG. 1 shows an example of a process for determining distance measurement conditions. Fig.15 The process is described in the flowchart in . The distance measurement conditions include, for example, a recharging method used in the light receiving circuit 11 .

[0112] At the beginning, power is supplied and the light receiving device 100 is activated (step S100). Then, the light receiving device 100 measures the number Nr of SPADs that react in the period when the light emitting element does not emit light (step S101). Here, the measurement circuit 30 can count the pulses output from the plurality of light receiving circuits 11 (e.g., circuit 10) to obtain the number Nr of SPADs that react. The measurement circuit 30 transmits the number Nr of SPADs that react to the control circuit 40.

[0113] Next, the control circuit 40 determines the recharging method to be used by the light receiving circuit 11 based on the number Nr of the SPADs that react (step S102). Here, the control circuit 40 may determine the recharging method to be used by the light receiving circuit 11 based on the number Nr of the SPADs that react obtained by the measurement circuit 30. In step S102, for example, the recharging method may be selected as follows: Fig.14 One of the specified modes in Table 71 in.

[0114] The control circuit 40 (more specifically, the SPAD controller 221) sends a control signal via the signal line l_ct. As a result, the light receiving circuit 11 can perform switch switching, for example, according to the recharging method. The measurement circuit 30 can perform distance measurement (step S103) based on the setting determined in step S102. After performing the process of step S103, the process of step S101 and thereafter can be performed again at the timing when the distance measurement is not performed (in other words, the light emitting element is not emitted). As a result, the light receiving device 100 can be set according to the change in the illumination of the environment.

[0115] The optical receiving device according to the present disclosure may include: a first optical receiving circuit, configured so that a recharging method for an optical receiving element can be switched; and a control circuit, configured to control the recharging method for the first optical receiving circuit based on a signal output by the first optical receiving circuit through a reaction with photons. In addition, the optical receiving circuit according to the present disclosure may include a plurality of first optical receiving circuits. In this case, the control circuit is configured to control the recharging method for at least one first optical receiving circuit based on the signals output by the plurality of first optical receiving circuits. As the optical receiving element, for example, an avalanche photodiode may be used. The above-mentioned photodiode PD is an example of an optical receiving element. In addition, circuit 10 ( Fig. 9 ) is an example of a first light receiving circuit. However, the first light receiving circuit may be a circuit having a configuration different from this.

[0116] The recharging method for the light receiving element in the first light receiving circuit may include at least one of passive recharging, active recharging, and a combination of passive recharging and active recharging. In addition, the recharging method for the light receiving element in the first light receiving circuit may include at least one of a recharging current during a passive recharging operation and a time delay for generating a reset pulse during an active recharging operation.

[0117] In addition, the optical receiving device according to the present disclosure may further include: a measuring circuit configured to count the number of reactions in the plurality of first optical receiving circuits. In this case, the control circuit is configured to control a recharging method for at least one first optical receiving circuit based on the number of reactions.

[0118] The distance measuring device according to the present disclosure may include a light emitting element, a plurality of light receiving circuits and a control circuit. Each light receiving circuit is configured so that a recharging method for the light receiving element can be switched. The control circuit is configured to control a recharging method for at least one light receiving circuit based on a signal output by a plurality of light receiving circuits through a reaction with photons during a period when the light emitting element does not emit light. As the light receiving element, for example, an avalanche photodiode can be used. The above-mentioned photodiode PD is an example of a light receiving element. In addition, the circuit 10 ( Fig. 9) is an example of a light receiving circuit. However, the light receiving circuit may be a circuit having a configuration different from this.

[0119] Note that it is not necessary for all of the multiple optical receiving circuits 11 provided in the optical receiving device 100 to be circuits that can switch the recharging method (e.g., circuit 10). For example, in the optical receiving device, some of the multiple optical receiving circuits 11 may be circuits that can switch the recharging method, and the remaining optical receiving circuits in the multiple optical receiving circuits 11 may be passive recharging circuits (e.g., circuit 13). In other words, the optical receiving device according to the present disclosure may also include a plurality of second optical receiving circuits configured to perform passive recharging of the optical receiving element. In addition, some of the optical receiving circuits 11 of the optical receiving device may be active recharging circuits. Therefore, the optical receiving device according to the present disclosure may also include a plurality of third optical receiving circuits configured to perform active recharging of the optical receiving element.

[0120] Fig.16 and Fig.17 The plan view in shows an example of the correspondence between pixels and recharging circuits. Fig.16 Pixels 50 to 54 are shown. In pixels 50 to 54, pixel 50 is equipped with a photodiode with a relatively large area of ​​a light receiving surface. For example, a photodiode having a circuit (e.g., circuit 10) that can switch a recharging method can be installed to pixel 50. In contrast, pixels 51 to 54 are each equipped with a photodiode with a relatively small area of ​​a light receiving surface. For example, a photodiode with a passive recharging circuit (circuit 13) can be installed to each of pixels 51 to 54.

[0121] Fig.17 Pixel 55 and pixel 56 are shown. Pixel 55 is covered by a relatively large light shielding portion 75, so the area of ​​the opening surface 80 is small. For example, a photodiode having a passive recharging circuit (circuit 13) can be mounted to pixel 55. In contrast, pixel 56 is covered by a relatively small light shielding portion 76, so the area of ​​the opening surface 81 is large. For example, a photodiode having a circuit capable of switching the recharging method (e.g., circuit 10) can be mounted to pixel 56.

[0122] The probability that the light receiving circuit will detect a photon and enter the dead time depends on the area of ​​the light receiving surface or opening surface of the photodiode and the illumination of the environment. Fig.16 and Fig.17As illustrated, according to the area of ​​the light receiving surface or the opening surface of the photodiode, a light receiving circuit whose sensitivity is adjusted and supports various illuminations can be prepared. For example, a circuit capable of switching the recharging method (e.g., circuit 10) can be installed in a pixel where the probability of entering the dead time is estimated to be relatively high, and a passive recharging circuit (e.g., circuit 13) can be installed in a pixel where the probability of entering the dead time is estimated to be relatively low. Compared with the case where the circuit capable of switching the recharging method is installed in all pixels, this can reduce power consumption and cost while maintaining the accuracy of photon detection.

[0123] In other words, in the light receiving device according to the present disclosure, a first light receiving circuit may be connected to a first pixel, and a second light receiving circuit may be connected to a second pixel having a light receiving surface or opening surface smaller than that of the first pixel.

[0124] The control circuit 40 may uniformly perform the same setting on a plurality of light receiving circuits 11. For example, the control circuit 40 may set the same recharging method to a plurality of light receiving circuits 11. However, the setting details for the plurality of light receiving circuits 11 do not need to be the same. For example, the control circuit 40 may set different recharging methods according to the light receiving circuits 11. For example, a predetermined ratio of light receiving circuits 11 may be made to perform active recharging, while the remaining light receiving circuits 11 may perform passive recharging. For example, 40% of the light receiving circuits may be set to active recharging, while 60% of the light receiving circuits may be set to passive recharging.

[0125] Fig.18 An example of setting distance measurement conditions for the region of each image is shown. Fig.19 An example of setting distance measurement conditions for each image is shown. Fig.18 and Fig.19 An image imaged by a car traveling along a highway viaduct is shown. The image includes area A1, area A2, and area A3. Area A1 corresponds to the sky portion and has a relatively high illumination. Area A2 corresponds to the portion that is in the shadow due to the viaduct and has a relatively low illumination. In addition, area A3 corresponds to the remaining portion. The greater the illumination of the area in the image, the more interference light there is during distance measurement. Therefore, a recharging method with an expected short dead time can be set for the optical receiving circuit that images area A1. A recharging method with an expected suppression of power consumption is set for the optical receiving circuit that images area A2.

[0126] For example, active recharging can be performed in the light receiving circuit that images the area A1. Passive recharging can also be performed in the light receiving circuit that images the area A2. Fig.13The method described can estimate the illumination of each area in the image. For example, the histogram generator 31 can generate the following for each group of light receiving circuits imaging each area: Fig.13 If the values ​​of the vertical axis of the histogram are normalized by the number of light receiving circuits (pixels) that image each area, the illuminance of multiple areas can be compared.

[0127] In addition, a parameter that can expect a short dead time can be set for the light receiving circuit that images the area A1, and a parameter that can expect to suppress power consumption can be set for the light receiving circuit that images the area A2. For example, for the area A1, the time delay td for the recharge pulse can be set to be short, or the recharge current can be set to be large. For example, for the area A2, the time delay td for the recharge pulse can be set to be long, or the recharge current can be set to be small.

[0128] Note that in the presence of Fig.18 In the case where there is a mixture of pixels with high illumination and pixels with low illumination in area A3 in the image, the recharging method for the light receiving circuit can be set according to the pixel with the highest illumination. As a result, high ranging accuracy can be maintained. In addition, the recharging method for the light receiving circuit used to image area A3 can be determined based on the average illumination within area A3.

[0129] In other words, the control circuit of the light receiving device according to the present disclosure may be configured to control the recharging method for the first light receiving circuit for each region of the captured image.

[0130] Due to the function of the control circuit 40 or the topology of the signal line l_ct for transmitting the control signal, there is a case where only uniformly making the settings of the plurality of light receiving circuits the same can be performed. In addition, there may also be a specified implementation method for performing the recharging method in units of groups of light receiving circuits. In addition, there is a case where it is desirable to avoid complicating the control algorithm regardless of the granularity at which control can be performed.

[0131] Therefore, the same recharging method can be set for the entire image. In the case where ranging accuracy is given the highest priority, the control circuit 40 determines the recharging method to be set to multiple light receiving circuits based on the light receiving circuit or group of light receiving circuits that measured the highest illuminance. In addition, an image area that requires particularly high ranging accuracy can be specified, and the recharging method to be set to multiple light receiving circuits can be determined based on the illuminance measured by the light receiving circuit that images the area. For example, in the application field of vehicle-mounted equipment, it is possible to Fig.17 The distance measurement condition for the entire image is determined by the illuminance measured in area A5 in which there is a high possibility that other cars, pedestrians, animals, etc. appear.

[0132] Areas where other cars, pedestrians, animals, etc. are likely to appear can be pre-specified based on the coordinates in the height direction in the image. In addition, the measurement circuit 30 can use machine learning such as neural networks to dynamically extract areas in the image where other cars, pedestrians, animals, etc. are likely to appear. In this case, the measurement circuit 30 can generate training data based on images obtained by multiple light receiving circuits (multiple SPADs). In addition, the measurement circuit 30 can generate training data based on images imaged by other image sensors.

[0133] In other words, the control circuit of the light receiving device according to the present disclosure may be configured such that the control circuit controls the recharging method for a plurality of first light receiving circuits based on a signal corresponding to a portion of an area of ​​a captured image output by the first light receiving circuit.

[0134] The light receiving device according to the present disclosure may be Figure 1 and Figure 2 The distance measuring device includes a light emitting element and a distance calculating unit as shown in the device shown in FIG. However, the light receiving device according to the present disclosure does not necessarily need to include a distance measuring function. For example, a device in which the distance calculating unit 233 and the trigger circuit 254 are omitted may be used, such as Fig. 20 The light receiving device 201 can detect photons through the SPAD array and generate Fig.13 The light receiving device 201 can be connected to another device and add functions corresponding to the distance calculation unit, the trigger circuit, and the light emitting element. In addition, the light receiving device 201 can be used as a device for determining the recharging method. In this case, another distance measuring device can measure the distance based on the recharging method determined by the light receiving device 201.

[0135] Next, a description is given about an example of a light receiving device that performs (makes) an error determination based on a voltage signal output from a light receiving circuit and determines a recharging method.

[0136] Fig.21 is a schematic diagram showing an example of a light receiving device according to a first modification. Fig.21 In the optical receiving device 101 in the embodiment, the error detector 21 is connected between the optical receiving circuit 11 and the sampler 20. Each error detector 21 is configured to perform error detection based on the voltage signal output from the optical receiving circuit 11. For example, the error detector 21 is arranged at Figure 1 or Fig. 20 In the circuit block 241 of the optical receiving device 101. At least some of the plurality of optical receiving circuits 11 may be circuits (eg, circuit 13) that can switch the recharging method. Some of the optical receiving circuits 11 in the optical receiving device 101 may be passive recharging circuits or active recharging circuits.

[0137] Notice, Fig.21 The light receiving device configuration shown in is merely an example. For example, the error detector 21 may be connected between the sampler 20 and the input terminal of the measurement circuit 30. In addition, a circuit integrating the function of the sampler 20 and the function of the error detector 21 may be connected between the corresponding light receiving circuit 11 and the input terminal of the measurement circuit 30. In addition, the function corresponding to the error detector 21 may be implemented in the measurement circuit 30. In this case, it can be said that the measurement circuit 30 includes the error detector 21.

[0138] Fig. 22 The graph in shows an example of error detection by the error detector 21. Fig. 22 Graphs 65 to 67 in FIG. 6 show the waveforms of the cathode potential Vca of the photodiode PD and the output voltage Vp of the light receiving circuit 11 (inverter INV). In all the graphs, the horizontal axis indicates time.

[0139] Graph 65 shows a case where, due to high illumination, before the cathode potential Vca rises to a voltage higher than the threshold of the inverter INV, the photodiode PD re-reacts with the photons of the interfering light and the pulse width output by the inverter INV becomes too large (similar to Figure 4 61 in the graph). For example, the error detector 21 detects the rising edge of the pulse in the voltage signal output from the light receiving circuit 11. Then, the error detector 21 monitors the pulse width. The error detector 21 performs an error determination when the pulse width exceeds the threshold value t_h. For example, the error detector 21 may sample the voltage of the signal at a period t_s, and once the sampled voltage is continuously HIGH for n_h times, an error determination is performed. In this case, the values ​​of t_s and n_h may be set so that the relationship t_h=t_s×n_h is satisfied. In addition, error determination may be performed by a method different from this.

[0140] In the graph 66, because the recharge current in the light receiving circuit 11 is too large, the voltage between the two terminals of the photodiode PD does not drop to the breakdown voltage, and the quenching may stop. Therefore, the output voltage of the light receiving circuit 11 is stuck (similar to Figure 4 For example, the error detector 21 detects the rising edge of the pulse in the voltage signal output from the light receiving circuit 11. The error detector 21 then measures the period during which the output voltage from the light receiving circuit 11 is HIGH. If the period during which the output voltage from the light receiving circuit 11 is HIGH exceeds the threshold value t_h, the error detector 21 performs error determination. In the example of the graph 66, error determination can be performed by a method similar to that in the case of the graph 65.

[0141] In the graph 67, residual charge appears in the photodiode PD after reacting with the photon. Therefore, due to the light receiving circuit 11, even if the quenching and recharging operation is being performed, re-reaction with the photon occurs in the photodiode PD. Due to the re-reaction with the photon, the cathode potential Vca fluctuates. For example, after the falling edge of the pulse in the voltage signal from the light receiving circuit 11, when the period during which the output voltage of the light receiving circuit 11 is LOW is shorter than the threshold value t_l, the error detector 21 performs an error determination. For example, the error detector 21 may sample the voltage of the signal with a period t_s, and perform an error determination when the number of times the sampled voltage is continuously LOW is less than n_l. In this case, the values ​​of t_s and n_l may be set so as to satisfy the relationship t_l=t_s×n_l. In addition, error determination may be performed by a method different from this.

[0142] Here is a description of error determination in the case where the light receiving circuit 11 outputs a HIGH level (positive polarity) pulse upon photon detection. The error detector 21 may also perform error determination in the case where the light receiving circuit 11 outputs a LOW level (negative polarity) pulse. In this case, in the description given above, it is sufficient if the error detector 11 operates in a manner that replaces HIGH with LOW, replaces LOW with HIGH, replaces the falling edge of a pulse with the rising edge of a pulse, and replaces the rising edge of a pulse with the falling edge of a pulse.

[0143] In the case where error determination has been performed, the error detector 21 transmits an error signal to the measurement circuit 30. For example, the error detector 21 may transmit the error signal using a signal line separate from a signal line that transmits a pulse when a photon is detected. Alternatively, the error detector 21 may transmit by superimposing an error signal on a signal line that transmits a pulse when a photon is detected.

[0144] The error signal sent by the error detector 21 may include an error code. The error code is information for specifying the type of error detected by the error detector 21. For example, the error codes E1, E2, and E3 may be associated with the errors in the above-mentioned graphs 65 to 67, respectively. The measurement circuit 30 counts the number of erroneous determinations of the plurality of light receiving circuits 11. In addition, in the case where the error code is included in the error signal, the measurement circuit 30 may count the number of erroneous determinations for each error code. In addition to the error code, the error detector 21 may also send information related to the error. For example, the error detector 21 may send information about the interval t_ip between pulses detected by using the error signal to the measurement circuit 30 together with the error code E3. The measurement circuit 30 transmits the counted number of erroneous determinations to the control circuit 40.

[0145] The control circuit 40 may determine the recharging method based on the number of error determinations for the plurality of light receiving circuits 11. For example, the control circuit 40 may change the recharging method in the event that the number of error determinations exceeds a threshold value. In addition, the control circuit 40 may determine the recharging method based on an error code included in the error signal. For example, the control circuit 40 may determine the recharging method based on a ratio between corresponding error codes.

[0146] For example, in the case where the number of error determinations is greater than or equal to the threshold value and the error code E1 is included in the plurality of error signals at a predetermined or higher ratio, the control circuit 40 may increase the recharging current at the time of passive recharging or change the recharging method to active recharging. In addition, in the case where the number of error determinations exceeds the threshold value and the ratio of the error code E2 exceeds a predetermined value, the control circuit 40 may reduce the recharging current at the time of passive recharging or switch the recharging method to active recharging.

[0147] In the case where the number of erroneous determinations exceeds a threshold value and the ratio of error code E3 exceeds a predetermined value when passive recharging is performed by multiple light receiving circuits 11, the control circuit 40 may increase the recharging current. In the case where the number of erroneous determinations exceeds a threshold value and the ratio of error code E3 exceeds a predetermined value when active recharging is performed by multiple light receiving circuits 11, different processing may be performed according to the interval t_ip between the detected pulses. In the case where the difference between t_ip and the pulse delay td of active recharging is less than a predetermined value, the control circuit 40 may determine that the setting value td of the pulse delay is too low and cause the control circuit 40 to change the pulse delay td to a larger value. In addition, in the case where the difference between t_ip and the pulse delay td of active recharging is greater than or equal to a predetermined value, the control circuit 40 may change the pulse delay td of active recharging to a smaller value.

[0148] In the above description, an example is given of a case where the control circuit 40 determines the recharging method based on the ratio of the error code. However, the control circuit 40 may determine the recharging method by a method different from this. For example, the control circuit 40 may compare the number of error signals having corresponding error codes with a threshold value, and determine the recharging method according to the determination result of the comparison.

[0149] Fig.23 The table in indicates an example of the operation mode of the light receiving device 101. Fig.23In Table 72 in, five operation modes M1 to M5 are defined. In mode M1 and mode M2, active recharging is performed. In mode M2, the setting value of the pulse delay of active recharging is larger than that in mode M1. In modes M3 to M5, passive recharging is performed. The setting value of the recharging current becomes larger in the order of modes M5, M4 and M3. Therefore, the length of the dead time expected in the optical receiving circuit 11 becomes shorter in the order of modes M5, M4, M3, M2 and M1. However, the power consumption increases in the order of modes M5, M4, M3, M2 and M1.

[0150] Using a mode that defines a recharging method including parameters can avoid complicating the processing performed by the measurement circuit 30 and the control circuit 40. For example, the measurement circuit 30 and the control circuit 40 can switch the operation mode to achieve the change of the recharging method as described above.

[0151] Fig.24 The flowchart in FIG. 1 shows an example of a process for determining a distance measurement condition according to the light receiving device 101. Fig.24 The flowchart in describes the process.

[0152] At the beginning, power is supplied and the light receiving device 101 is activated (step S110). Then, the light receiving device 101 counts the errors of multiple light receiving circuits in the period when the light emitting element does not emit light (step S111). In step S111, the measurement circuit 30 can receive an error signal from the error detector 21 and count the errors based on the error signal. For example, the measurement circuit 30 can obtain the total number of the number of error determinations by receiving the error signal. In addition, the measurement circuit 30 can obtain the number of error determinations for a single error code. In this way, the measurement circuit 30 can count errors by various methods. The measurement circuit 30 transmits information about the number of error determinations to the control circuit 40.

[0153] Next, the control circuit 40 determines the recharging method to be used by the light receiving circuit 11 based on the error count (step S112). Then, the control circuit 40 counts errors again in a state where the determined recharging method is executed, and determines whether the error count is less than a threshold value (step S113). The process is branched according to the determination result in step S113.

[0154] In the case where the detected error count is less than the threshold value (Yes in step S113), the measurement circuit 30 can perform distance measurement based on the setting determined in step S112 (step S114). In the case where the detected error count is greater than or equal to the threshold value (No in step S113), the light receiving device 101 returns to step S112. Note that after the process of step S114 is performed, the process of step S111 and thereafter can be performed again in a period in which the distance measurement is not performed (in other words, the light emitting element is not emitted). As a result, the light receiving device 101 can be set according to the change in the illumination of the environment.

[0155] The optical receiving device 101 may be started and based on the error count obtained in step S111, the operation mode in the initial state of the optical receiving device 101 may be determined. For example, in the case where the error count in step S111 is greater than a predetermined value, the initial operation mode of the optical receiving device 101 may be set to mode M1. In addition, in the case where the error count in step S111 is less than a predetermined value, the initial operation mode of the optical receiving device 101 may be set to mode M5.

[0156] The control circuit 40 can determine the changed operation mode based on the operation mode in the initial state. For example, in the case where the initial operation mode is mode M5, when the error count is greater than or equal to the threshold, the operation mode can be changed to mode M4. Similarly, in mode M4, when the error count is greater than or equal to the threshold, the operation mode can be changed to mode M3. In this way, after repeatedly performing the change of the operation mode until the error count becomes less than the threshold, the ranging process can be started. In this way, a balance can be achieved between power consumption and ranging accuracy.

[0157] In addition, in the case where the operation mode in the initial state is mode M1, when the error count is less than the threshold value, the operation mode can be changed to mode M2. In mode M2, the operation mode can also be changed to M3 when the error count is less than the threshold value. In this way, the start can be performed in the operation mode in which the expected dead time is the shortest, and when the error count is less than the threshold value, it can be changed to an operation mode that suppresses power consumption more. When this method is used, power consumption can be prevented from being greater than necessary.

[0158] Note that the optical receiving device 101 does not necessarily need to be adjusted as described above. For example, the optical receiving device 101 may obtain an error count in an operation mode of an initial state, and when the error count is less than a threshold, immediately start distance measurement without changing the operation mode.

[0159] In the light receiving device 101, the arrangement of the plurality of light receiving circuits 11 can be adjusted according to the illumination of the environment. As a result, high ranging accuracy can be ensured.

[0160] Note that, similar to the optical receiving device 100, the control circuit 40 of the optical receiving device 101 can set the recharging method different between the respective optical receiving circuits 11. Similarly, the control circuit 40 of the optical receiving device 101 can set the same recharging method to the plurality of optical receiving circuits 11. In addition, the control circuit 40 of the optical receiving device 101 can set parameters different between the respective optical receiving circuits 11. In other words, the control circuit 40 of the optical receiving device 101 can set the same operation mode to the plurality of optical receiving circuits 11. In addition, the control circuit 40 of the optical receiving device 101 can set the operation mode different between the respective optical receiving circuits 11.

[0161] The optical receiving device according to the present disclosure may further include an error detector configured to perform error determination based on the waveform of the signal output by the first optical receiving circuit. In this case, the control circuit is configured to control the recharging method for at least one first optical receiving circuit based on the number of error determinations for the signals output by the plurality of first optical receiving circuits. In addition, the error detector may be configured to perform error determination on at least one of a signal having a pulse width exceeding a first threshold and a signal having an interval between pulses less than a second threshold. The above threshold t_h is an example of a first threshold. In addition, the above threshold t_l is an example of a second threshold.

[0162] In addition, the light receiving device 101 may count errors for each image area and determine the distance measurement condition (eg, recharging method) for each image area, such as Fig.18 In addition, Fig.19 As shown, the light receiving device 101 can count errors for each image area and set the same distance measurement conditions for the entire image based on the counted results. The light receiving device 101 can be a distance measuring device including a light emitting element 255, a distance measuring unit 234, and a trigger circuit 254. In addition, the light receiving device 101 can be a device in which the light emitting element 255, the distance measuring unit 234, and the trigger circuit 254 are omitted.

[0163] Next, a description is given of an example of a light receiving device including a function for correcting an output signal of a light receiving circuit in a case where the signal is subjected to erroneous determination.

[0164] Fig.25 The schematic diagram in FIG. 1 shows an example of a light receiving device according to a second modification. Fig.25In the optical receiving device 102 in FIG. 1 , the error correction circuit 22 is connected between the optical receiving circuit 11 and the sampler 20. Each error correction circuit 22 is configured to correct the voltage signal determined to be in an error state based on the voltage signal output from the optical receiving circuit 11. Each error correction circuit 22 corresponds to the result of adding a function for converting a voltage signal that has been subjected to error determination into a voltage signal that is not in an error state to the error detector 21. For example, the error correction circuit 22 is set Figure 1 or Fig. 20 The configuration and function of the optical receiving device 102 are similar to those of the optical receiving device 101 described above, except that the error detector 21 is replaced by the error correction circuit 22.

[0165] Notice, Fig.25 The configuration of the light receiving device shown in is merely an example. For example, the error correction circuit 22 may be connected between the sampler 20 and the input terminal of the measurement circuit 30. In addition, a circuit integrating the function of the sampler 20 and the function of the error correction circuit 22 may be connected between the input terminals of each light receiving circuit 11 and the measurement circuit 30. Note that a function for converting a voltage signal that has been subjected to an erroneous determination into a voltage signal that is not in an erroneous state may be implemented at the input stage of the measurement circuit 30. In this case, the measurement circuit 30 may correct the voltage signal output from the light receiving circuit 11 based on the error signal received from the error detector 21. In other words, the measurement circuit 30 may adopt a configuration including the error correction circuit 22.

[0166] At least some of the plurality of light receiving circuits 11 may be circuits (eg, circuit 13) that can switch the recharging method. Note that some of the light receiving circuits 11 in the light receiving device 101 may be passive recharging circuits or active recharging circuits.

[0167] Fig.26 and Fig. 27 The graphs in show an example of a process for correcting a voltage waveform in the light receiving device 102. In all the graphs, the horizontal axis indicates time.

[0168] Fig.26 The graph 73 in FIG. 7A shows the waveforms of the input voltage Vai of the error correction circuit 22, the output voltage Vao of the error correction circuit 22, and the error signal Ves. In the example in the graph 73, passive recharging is performed by the light receiving circuit 11, and a waveform similar to that in the graph 61 ( Figure 4 ) and graph 65( Fig. 22) phenomenon. In the graph 73, the pulse width output from the light receiving circuit 11 becomes too large. For example, the error correction circuit 22 detects the rising edge of the pulse in the voltage signal output from the light receiving circuit 11. Then, the error correction circuit 22 monitors the pulse width. The error correction circuit 22 outputs the input signal as it is until an error determination is performed. In the case where the pulse width exceeds the threshold value t_h, the error correction circuit 22 performs an error determination. When an error determination is performed during pulse detection, the error correction circuit 22 masks the portion of the pulse that exceeds the threshold value t_h.

[0169] In the example of the graph 73, the error correction circuit 22 outputs a HIGH voltage in the portion of the period t_h from the rising edge of the pulse. Then, the error correction circuit 22 outputs a LOW voltage in the portion corresponding to the period t_m1 after the pulse width exceeds t_h. In this way, even in the case where the light receiving circuit 11 outputs a pulse whose pulse width exceeds the threshold t_h, the error correction circuit 22 can correct the pulse to a pulse whose pulse width is equal to the threshold t_h. Note that in the example of the graph 73, in the period t_m1 where the pulse is masked, the voltage of the error signal Ves becomes HIGH. As a result, a notification that an error determination has been performed can be performed to the measurement circuit 30 as a subsequent stage. Note that the error correction circuit 22 can notify the measurement circuit 30 of the error code. As a result, the control circuit 40 can determine the recharging method based on the error type rather than just the number of error determinations.

[0170] The error correction circuit 22 can sample the input voltage Vai at a period of t_s, and perform error determination when the sampled voltage is continuously at the HIGH level for n_h times. Here, the values ​​of t_s and n_h can be set so that the relationship t_h=t_s×n_h is satisfied. For example, t_s=1 nanosecond, n_h=10 and t_h=10 nanoseconds can be set. However, error determination can be performed by a method different from this. Note that even if the curve graph 62 ( Figure 4 ) and graph 66( Fig. 22 ) phenomenon, the error correction circuit 22 can also correct the waveform of the voltage signal and output a pulse with a pulse width equal to the threshold t_h.

[0171] Fig. 27 The graph 74 in FIG. 74 shows the waveforms of the input voltage Vai of the error correction circuit 22, the output voltage Vao of the error correction circuit 22, and the error signal Ves. In the example of the graph 74, active recharging is performed by the light receiving circuit 11. In the example of the graph 74, the output voltage Vai from the light receiving circuit 11 (in other words, the input voltage Vai of the error correction circuit 22) is different from the graph 67 ( Fig. 22) in the measurement circuit 30. The error correction circuit 22 outputs the input signal as it is until error determination is performed. For example, after the falling edge of the pulse in the input voltage Vai, when the period during which the input voltage Vai is LOW is shorter than the threshold value t_1, the error correction circuit 22 performs error determination. The error correction circuit 22 may output a HIGH error signal Ves after performing error determination. In addition, the error correction circuit 22 may notify the measurement circuit 30 of the error code. The error correction circuit 22 masks the pulse in a predetermined period t_m2 after error determination.

[0172] In the example in the graph 74, the error correction circuit 22 outputs a voltage at a LOW level in the period t_m2 after the error determination. This period t_m2 will be referred to as a masking period. After the error determination, when the masking period t_m2 has passed, the error correction circuit 22 outputs the input signal as it is again. For example, in the graph 74, after the masking period t_m2 has passed, the error correction circuit 22 outputs a pulse again. As the masking period t_m2, for example, a value greater than the threshold t_1 can be set.

[0173] In addition, the error correction circuit 22 can adjust the masking period t_m2 according to the situation of the error determination of the input voltage Vai. For example, in the input voltage Vai in the graph 74, after the first pulse arrives, three pulses arrive at intervals shorter than the threshold t_l. Therefore, the error correction circuit 22 performs error determination three times in succession at the timing indicated by the white arrow. However, the error correction circuit 22 can release the error state after performing the final error determination without performing the error determination within the period t_r. After releasing the error state, the error correction circuit 22 outputs the input pulse as it is again. As in the example in the graph 74, when the error state is released, the error correction circuit 22 can set the error signal Ves to LOW. Note that during the duration of the period t_m2, the error correction circuit 22 can output a discontinuous HIGH error signal Ves each time an error determination is performed, instead of continuously outputting the HIGH error signal Ves.

[0174] For example, the error correction circuit 22 may sample the voltage of the signal at a period of t_s, and perform error determination when the number of times the sampled voltage is continuously LOW is less than n_l. The values ​​of t_s and n_l may be set so that the relationship t_l=t_s×n_l is satisfied. However, the error correction circuit 22 may perform error determination by a method different from this.

[0175] Here, a description is given about error determination and error correction in the case where the light receiving circuit 11 outputs a HIGH level (positive polarity) pulse upon photon detection. However, the error correction circuit 22 may also perform error determination in the case where the light receiving circuit 11 outputs a LOW level (negative polarity) pulse. In this case, in the description given above, it is sufficient if the error correction circuit 22 operates in a manner that replaces HIGH with LOW, replaces LOW with HIGH, replaces the falling edge of a pulse with the rising edge of a pulse, and replaces the rising edge of a pulse with the falling edge of a pulse.

[0176] The optical receiving device according to the present disclosure may further include an error correction circuit, which is configured to make an error determination based on the waveform of the signal output by the first optical receiving circuit and correct the waveform of the signal for which the error determination is made. In addition, the error correction circuit may be configured to perform an error determination on at least one of a signal whose pulse width exceeds a first threshold and a signal whose interval between pulses is less than a second threshold. In addition, the control circuit may be configured to control a recharging method for at least one first optical receiving circuit based on the number of error determinations of the signals output by the plurality of first optical receiving circuits.

[0177] Fig. 9 The circuit 10 capable of switching the recharging method is shown. However, the circuit 10 is merely an example of a circuit capable of switching the recharging method. Therefore, the circuit capable of switching the recharging method may have a configuration different from this.

[0178] Fig.28 The circuit diagram in shows an example of a circuit according to the third modification example. Fig.28 The circuit 12 in FIG. 1 corresponds to a circuit resulting from omitting the transistor TR2 and the switch SW3 in the circuit 10. In other words, in the circuit 12, the portion of the circuit 10 for latching the state of the transistor TR1 is omitted. In the circuit 12, when SW1 is set to on and SW2 is set to off, passive recharging is performed. In addition, in the circuit 12, active recharging is performed when SW1 is set to off and SW2 is set to on. Note that in the circuit 12, when both SW1 and SW2 are set to on, passive recharging and active recharging are performed. Note that the operation of the circuit 12 is similar to the operation of the above-described circuit 10 except that there is no operation for latching the state of the transistor TR1.

[0179] The optical receiving circuit according to the present disclosure may include an optical receiving element, a load element, a first switch, an inverter, a first transistor, a second switch and a pulse generator. The load element is connected to a reference potential. The first switch is connected between the load element and the optical receiving element. The inverter is connected to a first signal line between the first switch and the optical receiving element via a second signal line. The first transistor is connected to the reference potential. The second switch is connected between the first transistor and the second signal line. The pulse generator is connected to a third signal line as a rear stage of the inverter, and a first control electrode of the first transistor.

[0180] Here, the photodiode PD is an example of a light receiving element. The light receiving element may be an avalanche photodiode. Fig. 9 and Fig.28 The transistor TR0 in is an example of a load element. The power supply potential Vdd is an example of a reference potential. The switch SW1 is an example of a first switch. The transistor TR1 is an example of a first transistor. The switch SW2 is an example of a second switch. The first signal line corresponds to a signal line connected, for example, between the switch SW1 and the photodiode PD. The signal line Lin is an example of a second signal line. The signal line Lout is an example of a third signal line. The gate of the transistor TR1 is an example of a first control electrode of the first transistor.

[0181] The pulse generator may be configured to output a pulse to the first control electrode according to the voltage of the third signal line. In addition, the pulse generator may be configured to output a pulse to the first control electrode with a time delay when the voltage level of the third signal line changes. The pulse generator may be configured to adjust the time delay according to a control signal provided from the control circuit. A pulse generator having any circuit configuration may be used.

[0182] In addition, the optical receiving circuit according to the present disclosure may further include a second transistor connected to the reference potential, and a third switch connected between the second transistor and the second signal line. In this case, the second control electrode of the second transistor is connected to the third signal line. Fig. 9 The transistor TR2 in FIG. 1 is an example of a second transistor. Fig. 9 The switch SW3 in FIG. 1 is an example of a third switch. In addition, for example, the second control electrode of the second transistor corresponds to the gate of the transistor TR2.

[0183] Fig.29 The circuit 14 in Table 70 corresponds to a circuit produced by omitting the load element 90 (transistor TR0) in the circuit 10. In other words, the circuit 14 is an active recharging circuit that does not perform passive recharging. The operation of the circuit 14 is similar to the case where, in the circuit 10, the switch SW1 is set to OFF, the switch SW2 is set to ON, and the switch SW3 is set to ON (switch setting st1 in Table 70).

[0184] The above-mentioned optical receiving devices 100 to 102 ( Figure 8 , Fig.21 and Fig.25 ) may be circuit 12 or circuit 14. In this case, the control circuit 40 may switch the switch SW1 and the switch SW2, and control the signal supplied to the signal line dctr. In addition, at least one of the above-mentioned circuits 10, 12, or 13 may be included in the plurality of light receiving circuits 11. As described above, the type of circuit used as the light receiving circuit 11 may be determined based on the area of ​​the light receiving surface or the opening surface of the photodiode (the possibility that the photodiode will enter the dead time). For example, the circuit 14 (active recharging circuit) may be installed in a pixel having a large area of ​​the light receiving surface or the opening surface.

[0185] Fig.30 The block diagram in shows an example of a ranging device. Fig.30 The distance measuring device 202 and the external processing circuit 300 are shown. The distance measuring device 202 corresponds to the components ( Figure 1 ) results in omitting the control circuit 220. The processing circuit 230 of the ranging device 202 is connected to the external processing circuit 300 via the transmission circuit 211 and the terminal S_OUT. In addition, the SPAD controller 221 of the ranging device 202 is connected to the external processing circuit 300 via the terminal S_IN and the communication circuit 210. For example, the external processing circuit 300 is a hardware circuit as an ASIC or FPGA. However, the external processing circuit 300 may be a computer including a central processing unit (CPU) and a memory. In this case, the processing circuit 300 provides various functions through a program stored in a storage device executed by the CPU.

[0186] The external processing circuit 300 performs the corresponding Figure 1 The control circuit 220 ( Figure 8 , Fig.21 and Fig.25 In other words, for the distance measuring device 202, a separate external processing circuit 300 can determine the recharging method for each light receiving circuit 11. For example, the external processing circuit 300 can receive the number Nr of SPADs that react during the period when the light emitting element does not emit light from the processing circuit 230, and determine the recharging method ( Figures 13 to 15 In addition, the external processing circuit 300 may determine a recharging method for each light receiving circuit 11 based on the error count ( Fig.24 method).

[0187] Note that the communication between the processing circuit 300 and the distance measuring device 202 may be performed by wire or may be performed wirelessly. In addition, the processing circuit 300 may determine the recharging method ( Nr ) for each light receiving circuit 11 based on the number Nr of reactive SPADs or the error count determined for each image area. Fig.18 and Fig.19 method).

[0188] By using the light receiving device, light receiving circuit and distance measuring device according to the present disclosure, the recharging method to be used can be determined according to the illumination of the environment. Therefore, regardless of the illumination of the environment, photons can be detected and distance measurement can be performed with high accuracy.

[0189] In addition, the optical receiving device, optical receiving circuit, and ranging device according to the present disclosure can perform passive recharging when it is determined that active recharging is not required. In addition, the recharging current can be suppressed during passive recharging, or the time delay for generating pulses for active recharging can be increased. Therefore, the power consumption required for photon detection or distance measurement can be suppressed. In addition, in the optical receiving device, optical receiving circuit, and ranging device according to the present disclosure, since the determination can be performed for each imaged image area and the recharging method or the parameters during recharging can be determined, the optimal performance according to the intended use can be achieved.

[0190] The technology of the present disclosure (the present technology) can be applied to various products. For example, the technology of the present disclosure can be implemented as a device installed in any of various types of mobile bodies, such as a car, an electric car, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility tool, an airplane, a drone, a ship, or a robot.

[0191] Fig.31 : is a block diagram depicting an example of a schematic configuration of a vehicle control system as an example of a moving body control system to which the technology according to the embodiment of the present disclosure can be applied.

[0192] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. Fig.31 In the example shown, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external vehicle information detection unit 12030, an in-vehicle information detection unit 12040, and an integrated control unit 12050. In addition, a microcomputer 12051, a sound / image output section 12052, and an in-vehicle network interface (I / F) 12053 are shown as a functional configuration of the integrated control unit 12050.

[0193] The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 serves as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, a brake device for generating a braking force of the vehicle, etc.

[0194] 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 headlights, backup lights, brake lights, turn signals, or fog lights). In this case, a radio wave transmitted from a mobile device may be input to the body system control unit 12020 as a substitute for a signal of a key or various switches. The body system control unit 12020 receives these input radio waves or signals and controls the door lock device, power window device, lights, etc. of the vehicle.

[0195] The external vehicle information detection unit 12030 detects information about the outside of the vehicle including the vehicle control system 12000. For example, the external vehicle information detection unit 12030 is connected to the imaging unit 12031. The external vehicle information detection unit 12030 causes the imaging unit 12031 to image the image outside the vehicle and receive the captured image. Based on the received image, the external vehicle information detection unit 12030 can perform a process of detecting an object such as a person, a vehicle, an obstacle, a sign, or a character on the road surface, or a process of detecting a distance therefrom.

[0196] 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 light.

[0197] The vehicle-mounted information detection unit 12040 detects information about the interior of the vehicle. The vehicle-mounted information detection unit 12040 is connected to, for example, a driver state detection unit 12041 that detects the state of the driver. For example, the driver state detection unit 12041 includes a camera that images the driver. Based on the detection information input from the driver state detection unit 12041, the vehicle-mounted 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.

[0198] 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 inside or outside of the vehicle, which is obtained by the external vehicle information detection unit 12030 or the in-vehicle information detection unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing functions of an advanced driver assistance system (ADA), including collision avoidance or impact mitigation of a vehicle, following driving based on a following distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, and the like.

[0199] In addition, the microcomputer 12051 can perform collaborative control aimed at automatic driving, which enables the vehicle to travel autonomously without relying on the driver's operation, etc. by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the outside or inside of the vehicle, which is obtained by the external vehicle information detection unit 12030 or the on-board information detection unit 12040.

[0200] In addition, the microcomputer 12051 can output a control command to the body system control unit 12020 based on information about the outside of the vehicle, which is obtained by the outside vehicle information detection unit 12030. For example, the microcomputer 12051 can perform cooperative control aimed at preventing glare by controlling the headlights according to the position of a preceding vehicle or an oncoming vehicle detected by the outside vehicle information detection unit 12030 so as to change a high beam to a low beam.

[0201] The sound / image output unit 12052 sends an output signal of at least one of sound and image to an output device that can visually or auditorily notify the occupants of the vehicle or the outside of the vehicle of information. Fig.31 In the example of FIG. 1 , an audio speaker 12061, a display portion 12062, and a dashboard 12063 are shown as output devices. The display portion 12062 may include, for example, at least one of an in-vehicle display and a head-up display.

[0202] Fig.32 The figure depicts an example of the installation position of the imaging unit 12031.

[0203] exist Fig.32 In the figure, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104 and 12105.

[0204] Imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at various positions at the front nose, side mirrors, rear bumper, and rear door of the vehicle 12100, and at a position at the upper portion of the windshield inside the vehicle. The imaging unit 12101 provided to the front nose and the imaging unit 12105 provided to the upper portion of the windshield inside the vehicle mainly obtain images in front of the vehicle 12100. The imaging units 12102 and 12103 provided to the side mirrors mainly obtain images on the sides of the vehicle 12100. The imaging unit 12104 provided to the rear bumper or rear door mainly obtains images behind the vehicle 12100. The imaging unit 12105 provided to the upper portion of the windshield inside the vehicle is mainly used to detect vehicles, pedestrians, obstacles, signals, traffic signs, lanes, etc. in front.

[0205] By the way, Fig.32 An example of the shooting range of the imaging units 12101 to 12104 is depicted. Imaging range 12111 represents the imaging range of the imaging unit 12101 set to the front nose. Imaging ranges 12112 and 12113 respectively represent the imaging ranges of the imaging units 12102 and 12103 set to the side mirrors. Imaging range 12114 represents the imaging range of the imaging unit 12104 set to the rear bumper or the rear door. For example, by superimposing the image data imaged by the imaging units 12101 to 12104, a bird's-eye view of the vehicle 12100 observed from above is obtained.

[0206] At least one of the imaging sections 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging sections 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.

[0207] 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, thereby extracting the closest three-dimensional object that appears on the path of the vehicle 12100 and moves in substantially the same direction as the vehicle 12100 at a predetermined speed (e.g., equal to or exceeding 0 km / hour) 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 aimed at performing automatic driving can be performed, which makes the vehicle travel autonomously without relying on the operation of the driver, etc.

[0208] For example, the microcomputer 12051 can classify the three-dimensional object data about the three-dimensional object into three-dimensional object data of two-wheeled vehicles, standard-sized vehicles, large-sized vehicles, pedestrians, utility poles, 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 obstacle avoidance. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that the driver of the vehicle 12100 can visually identify and obstacles that the driver of the vehicle 12100 is difficult to visually identify. Then, the microcomputer 12051 determines the collision risk, which indicates the risk of collision with each obstacle. In the case where 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. Therefore, the microcomputer 12051 can assist driving to avoid collisions.

[0209] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 may identify a pedestrian by determining whether there is a pedestrian in the imaging images of the imaging units 12101 to 12104. For example, such identification of pedestrians is performed by a process of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras and by a process of performing pattern matching processing on a series of feature points representing the contours of the object. When the microcomputer 12051 determines that there is a pedestrian in the captured images of the imaging units 12101 to 12104 and thus identifies the pedestrian, the sound / image output unit 12052 controls the display unit 12062 to display a square outline for emphasis so as to be superimposed on the identified pedestrian. The sound / image output unit 12052 may also control the display unit 12062 so that an icon or the like representing a pedestrian is displayed at a desired position.

[0210] The above is a description of an example of a vehicle control system to which the technology in the present disclosure can be applied. The technology in the present disclosure can be applied to the imaging unit 12031. For example, Figure 1 The distance measuring device 200 and Figure 2 The light emitting element 255 in the imaging unit 12031 is implemented. In addition, the light emitting element 255 in the imaging unit 12031 can be implemented Figure 8 The optical receiving device 100, Fig. 20 The light receiving device 201, Fig.21 The light receiving device 101, Fig.25 The light receiving device 102 and Fig.30At least one of the external processing circuit 300 and the distance measuring device 202 in the vehicle 12100. The technology in the present disclosure is applied to the imaging unit 12031, thereby performing distance measurement with high accuracy regardless of the illumination of the environment. As a result, the safety of the vehicle 12100 can be improved.

[0211] Note that the present technology can have the following configurations.

[0212] (1) A light receiving device comprising:

[0213] a first light receiving circuit configured so that a recharging method for the light receiving element is switched; and

[0214] A control circuit is configured to control a recharging method for the first light receiving circuit based on a signal output by the first light receiving circuit through a reaction with photons.

[0215] (2) The light receiving device according to (1), wherein:

[0216] The recharging method includes at least one of passive recharging, active recharging, and a combination of passive recharging and active recharging.

[0217] (3) The light receiving device according to (1) or (2), wherein:

[0218] The recharging method includes at least one of a recharging current in a passive recharging operation and a time delay in generating a reset pulse in an active recharging operation.

[0219] (4) The light receiving device according to any one of (1) to (3), further comprising:

[0220] A plurality of said first light receiving circuits, wherein:

[0221] The control circuit is configured to control a recharging method for at least one of the first light receiving circuits based on signals output by the plurality of the first light receiving circuits.

[0222] (5) The optical receiving device according to (4), further comprising:

[0223] A measuring circuit is configured to count the number of responses in the plurality of first light receiving circuits, wherein:

[0224] The control circuit is configured to control a recharging method for at least one first light receiving circuit based on the reaction quantity.

[0225] (6) The optical receiving device according to (4) or (5), further comprising:

[0226] an error detector configured to perform error determination based on a waveform of a signal output by the first light receiving circuit, wherein

[0227] The control circuit is configured to control the recharging method for at least one of the first light receiving circuits based on a number of erroneous determinations of signals output by a plurality of the first light receiving circuits.

[0228] (7) The light receiving device according to (6), wherein:

[0229] The error detector is configured to perform error determination on at least one of a signal having a pulse width exceeding a first threshold and a signal having an interval between pulses less than a second threshold.

[0230] (8) The light receiving device according to (4) or (5), wherein:

[0231] The error correction circuit is configured to perform error determination based on a waveform of a signal output by the first light receiving circuit, and correct the waveform of the signal on which the error determination was performed.

[0232] (9) The light receiving device according to (8), wherein:

[0233] The error correction circuit is configured to perform error determination on at least one of a signal having a pulse width exceeding a first threshold and a signal having an interval between pulses less than a second threshold.

[0234] (10) The light receiving device according to (8) or (9), wherein:

[0235] The control circuit is configured to control a recharging method for at least one of the first light receiving circuits based on a number of erroneous determinations of signals output by a plurality of the first light receiving circuits.

[0236] (11) The light receiving device according to any one of (4) to (10), wherein:

[0237] The control circuit is configured to control a recharging method for the first light receiving circuit for each area of ​​a captured image.

[0238] (12) The light receiving device according to any one of (4) to (10), wherein:

[0239] The control circuit is configured to control a recharging method for a plurality of the first light receiving circuits based on a signal corresponding to a portion of an area of ​​a captured image output by the first light receiving circuit.

[0240] (13) The light receiving device according to any one of (4) to (12), further comprising:

[0241] A plurality of second light receiving circuits, each second light receiving circuit being configured to perform passive recharging of the light receiving element.

[0242] (14) The light receiving device according to (13), wherein:

[0243] Each first light receiving circuit is connected to a first pixel, and

[0244] Each second light receiving circuit is connected to a second pixel having a light receiving surface or an opening surface smaller than that of the first pixel.

[0245] (15) The light receiving device according to any one of (1) to (14), wherein:

[0246] The light receiving element is an avalanche photodiode.

[0247] (16) A distance measuring device comprising:

[0248] Light emitting element;

[0249] a plurality of light receiving circuits configured so that a recharging method for the light receiving elements is switched; and

[0250] A control circuit is configured to control a recharging method for at least one of the light receiving circuits based on signals output by the plurality of light receiving circuits through reactions with photons during a period in which the light emitting element does not emit light.

[0251] (17) An optical receiving circuit comprising:

[0252] A light receiving element;

[0253] a load element, connected to a reference potential;

[0254] A first switch connected between the load element and the light receiving element;

[0255] an inverter connected to the first signal line between the first switch and the light receiving element via a second signal line;

[0256] a first transistor connected to a reference potential;

[0257] a second switch connected between the first transistor and the second signal line; and

[0258] A pulse generator is connected to a third signal line at a subsequent stage of the inverter and to the first control electrode of the first transistor.

[0259] (18) The optical receiving circuit according to (17), wherein:

[0260] The pulse generator is configured to output a pulse to the first control electrode according to a voltage of the third signal line.

[0261] (19) The optical receiving circuit according to (18), wherein:

[0262] The pulse generator is configured to output a pulse to the first control electrode with a time delay when a voltage level of the third signal line changes.

[0263] (20) The optical receiving circuit according to any one of (17) to (19), further comprising:

[0264] a second transistor connected to the reference potential; and

[0265] a third switch connected between the second transistor and the second signal line, wherein:

[0266] A second control electrode of the second transistor is connected to the third signal line.

[0267] Aspects of the present disclosure are not limited to each of the above-described embodiments, and include various modifications that may occur to those skilled in the art. The effects of the present disclosure are also not limited to the above-described details. In other words, various additions, modifications, and partial deletions may be made without departing from the concepts and elements of the present disclosure as defined in the claims and their equivalents.

[0268] Reference numerals list

[0269] OBJ: Object

[0270] 1: Detection Department

[0271] 10, 12, 13: Circuit

[0272] 11: Optical receiving circuit

[0273] 20: Sampler

[0274] 21: Error Detector

[0275] 22: Error correction circuit

[0276] 30: Measurement circuit

[0277] 40: Control circuit

[0278] 50, 51, 52, 53, 54, 55, 56: pixels

[0279] 75, 76: Shading part

[0280] 80, 81: Opening surface

[0281] 90: Load element

[0282] 91, 91, 92: Active recharging circuit

[0283] 100, 101, 102: Light receiving device

[0284] 200: Distance measuring device

[0285] 255: Light-emitting element.

Claims

1. A light receiving device, comprising: a plurality of first light receiving circuits configured so that a recharging method of a light receiving element for at least one of the plurality of first light receiving circuits is switched; and a control circuit configured to control the recharging method for the at least one first light receiving circuit based on signals output by the plurality of first light receiving circuits through reactions with photons; Wherein, the control circuit is configured to control the recharging method for the at least one first light receiving circuit based on the counted number of reactions in the plurality of first light receiving circuits or the number of erroneous determinations of signals output by the plurality of first light receiving circuits.

2. The light receiving device according to claim 1, wherein: The recharging method includes at least one of a combination of passive recharging and active recharging, passive recharging, and active recharging.

3. The light receiving device according to claim 1, wherein The recharging method includes at least one of a recharging current in a passive recharging operation and a time delay in generating a reset pulse in an active recharging operation.

4. The optical receiving device according to claim 1, further comprising: A measuring circuit is configured to count the number of reactions in the plurality of first light receiving circuits.

5. The optical receiving device according to claim 1, further comprising: An error detector is configured to perform the error determination based on a waveform of a signal output by the first light receiving circuit.

6. The light receiving device according to claim 5, wherein: The error detector is configured to perform error determination on at least one of a signal having a pulse width exceeding a first threshold and a signal having an interval between pulses less than a second threshold.

7. The optical receiving device according to claim 1, further comprising: An error correction circuit configured to perform error determination based on a waveform of a signal output by the first light receiving circuit and correct the waveform of the signal on which the error determination was performed.

8. The light receiving device according to claim 7, wherein: The error correction circuit is configured to perform error determination on at least one of a signal having a pulse width exceeding a first threshold and a signal having an interval between pulses less than a second threshold.

9. The light receiving device according to claim 7, wherein: The control circuit is configured to control a recharging method for at least one of the plurality of first light receiving circuits based on a number of erroneous determinations of signals output by the plurality of first light receiving circuits.

10. The light receiving device according to claim 1, wherein The control circuit is configured to control a recharging method for the first light receiving circuit for each region of a captured image.

11. The light receiving device according to claim 1, wherein: The control circuit is configured to control a recharging method for the at least one first light receiving circuit based on signals corresponding to a partial area of ​​the captured image output by the plurality of first light receiving circuits.

12. The optical receiving device according to claim 1, further comprising: A plurality of second light receiving circuits are configured to perform passive recharging of the light receiving elements.

13. The light receiving device according to claim 12, wherein: Each of the first light receiving circuits is connected to a first pixel, and Each of the second light receiving circuits is connected to a second pixel having a smaller light receiving surface than that of the first pixel or a smaller opening surface than that of the first pixel.

14. The light receiving device according to claim 1, wherein The light receiving element is an avalanche photodiode.

15. A distance measuring device, comprising: Light emitting element; a plurality of light receiving circuits configured so that a recharging method of a light receiving element for at least one of the plurality of light receiving circuits is switched; as well as a control circuit configured to control a recharging method for at least one of the plurality of light receiving circuits based on a signal output by the plurality of light receiving circuits through a reaction with photons during a period in which the light emitting element does not emit light, Wherein, the control circuit is configured to control the recharging method for the at least one light receiving circuit based on the counted number of reactions in the plurality of light receiving circuits or the number of erroneous determinations of signals output by the plurality of light receiving circuits.

16. An optical receiving circuit, comprising: A light receiving element; a load element, connected to a reference potential; A first switch connected between the load element and the light receiving element; an inverter connected to the first signal line between the first switch and the light receiving element via a second signal line; a first transistor connected to the reference potential; a second switch connected between the first transistor and the second signal line; as well as A pulse generator is connected to a third signal line at a subsequent stage of the inverter and to the first control electrode of the first transistor.

17. The optical receiving circuit according to claim 16, wherein: The pulse generator is configured to output a pulse to the first control electrode according to a voltage of the third signal line.

18. The optical receiving circuit according to claim 17, wherein: The pulse generator is configured to output a pulse to the first control electrode with a time delay when a voltage level of the third signal line changes.

19. The optical receiving circuit according to claim 16, further comprising: a second transistor connected to the reference potential; as well as A third switch is connected between the second transistor and the second signal line, wherein: A second control electrode of the second transistor is connected to the third signal line.

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