Photoelectric conversion device, optical detection system, and movable body

Abstract

The present photoelectric conversion device includes: an avalanche photodiode including an anode and a cathode; a switch connected to one node of the anode and the cathode, and a power line to which a driving voltage is to be applied, and configured to switch a resistance value between the one node and the power line; and a signal generation unit configured to generate a pulse signal for controlling switching of the switch. A value obtained by dividing a number of the pulse signals in a first exposure period by the first exposure period is different from a value obtained by dividing a number of the pulse signals in a second exposure period by the second exposure period, a length of the second exposure period being different from a length of the first exposure period.

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion device, an optical detection system, and a movable body for performing photoelectric conversion. Background Technology

[0002] Photoelectric conversion devices comprising pixel arrays are known, in which pixels, including multiple avalanche photodiodes (APDs), are arranged planarly in a two-dimensional array. In the PN junction region within the semiconductor region of each pixel, avalanche multiplication is caused by photocharge induced by a single photon.

[0003] Japanese Patent Application Publication No. 2020-123847 discusses a pixel including an APD, a quenching circuit, a signal control circuit, and a pulse generation circuit. The quenching circuit is connected to the APD, and the signal output from the APD is input to the signal control circuit. The pulse generation circuit is connected to both the quenching circuit and the signal control circuit. The pulse generation circuit controls the on / off state of the quenching circuit. Japanese Patent Application Publication No. 2020-123847 also discusses resetting the output signal for each pulse signal, thereby outputting a pulse signal corresponding to the input photon even under high brightness conditions.

[0004] Japanese Patent Application Publication No. 2020-123847 does not discuss the number and period of the pulse signals output within the exposure time period when the exposure time period varies. Japanese Patent Application Publication No. 2020-123847, however, considers the space for controlling the pulse signals based on their relationship to the exposure time period.

[0005] PTL 1: Japanese Patent Application Publication No. 2020-123847 Summary of the Invention

[0006] According to one aspect, a photoelectric conversion device includes: an avalanche photodiode, the avalanche photodiode including an anode and a cathode; a switch connected to a node of the anode and cathode and a power line to which a driving voltage will be applied, and configured to switch a resistance value between the node and the power line; and a signal generation unit configured to generate a pulse signal for controlling the switching of the switch, wherein a value obtained by dividing the number of pulse signals in a first exposure time period by the first exposure time period and multiplying the result by the first exposure time period is different from a value obtained by dividing the number of pulse signals in a second exposure time period by the second exposure time period and multiplying the result by the first exposure time period, the length of the second exposure time period being different from the length of the first exposure time period. Attached Figure Description

[0007] Figure 1 This is a diagram illustrating the configuration of a photoelectric conversion device.

[0008] Figure 2 An example illustrating the arrangement of the sensor substrate is provided.

[0009] Figure 3 Examples illustrating the arrangement of circuit boards are provided.

[0010] Figure 4A It is a block diagram of the equivalent circuit including photoelectric conversion elements.

[0011] Figure 4B It is a block diagram of the equivalent circuit including photoelectric conversion elements.

[0012] Figure 5 This is a diagram illustrating the relationship between the operation and output signal of an avalanche photodiode (APD).

[0013] Figure 6A This is a timing diagram of the control pulses of the photoelectric conversion device according to the first exemplary embodiment.

[0014] Figure 6B This is a timing diagram of the control pulses of the photoelectric conversion device according to the first exemplary embodiment.

[0015] Figure 6C This is a timing diagram of the control pulses of the photoelectric conversion device according to the first exemplary embodiment.

[0016] Figure 7A It is a timing diagram of the control pulses of the photoelectric conversion device based on the comparison configuration.

[0017] Figure 7B It is a timing diagram of the control pulses of the photoelectric conversion device based on the comparison configuration.

[0018] Figure 7C It is a timing diagram of the control pulses of the photoelectric conversion device based on the comparison configuration.

[0019] Figure 8 This is a flowchart illustrating an example of an operation mode of a photoelectric conversion device according to a first exemplary embodiment.

[0020] Figure 9A This is a timing diagram of the control pulses of a photoelectric conversion device according to a modified example of the first exemplary embodiment.

[0021] Figure 9B This is a timing diagram of the control pulses of a photoelectric conversion device according to a modified example of the first exemplary embodiment.

[0022] Figure 9C This is a timing diagram of the control pulses of a photoelectric conversion device according to a modified example of the first exemplary embodiment.

[0023] Figure 9D This is a timing diagram of the control pulses of a photoelectric conversion device according to a modified example of the first exemplary embodiment.

[0024] Figure 9E This is a timing diagram of the control pulses of a photoelectric conversion device according to a modified example of the first exemplary embodiment.

[0025] Figure 9F This is a timing diagram of the control pulses of a photoelectric conversion device according to a modified example of the first exemplary embodiment.

[0026] Figure 10A This is a timing diagram of the control pulses of the photoelectric conversion device according to the second exemplary embodiment.

[0027] Figure 10B This is a timing diagram of the control pulses of the photoelectric conversion device according to the second exemplary embodiment.

[0028] Figure 10C This is a timing diagram of the control pulses of the photoelectric conversion device according to the second exemplary embodiment.

[0029] Figure 11 This is a diagram illustrating the relationship between the number of incident photons and the count value during each exposure time period of the photoelectric conversion device according to the third exemplary embodiment.

[0030] Figure 12 An example of the arrangement of the circuit board of the photoelectric conversion device according to the third exemplary embodiment is illustrated.

[0031] Figure 13A This is a timing diagram of the control pulses of the photoelectric conversion device according to the third exemplary embodiment.

[0032] Figure 13B This is a timing diagram of the control pulses of the photoelectric conversion device according to the third exemplary embodiment.

[0033] Figure 14 This is a block diagram of an optical detection system according to a fourth exemplary embodiment.

[0034] Figure 15 This is a block diagram of an optical detection system according to a fifth exemplary embodiment.

[0035] Figure 16 This is a block diagram of an optical detection system according to a sixth exemplary embodiment.

[0036] Figure 17A This is a block diagram of an optical detection system according to a seventh exemplary embodiment.

[0037] Figure 17B This is a block diagram of an optical detection system according to a seventh exemplary embodiment.

[0038] Figure 18 This is a flowchart of an optical detection system according to a seventh exemplary embodiment.

[0039] Figure 19A These are illustrations illustrating specific examples of an electronic device according to an eighth exemplary embodiment.

[0040] Figure 19B These are illustrations illustrating specific examples of an electronic device according to an eighth exemplary embodiment. Detailed Implementation

[0041] The following exemplary embodiments are provided to illustrate the technical concept of the invention and are not intended to limit the invention. The size and positional relationships of the components illustrated in the drawings are sometimes enlarged to make the description clearer. In the following description, the same components are assigned the same reference numerals, and their descriptions are sometimes omitted.

[0042] Reference Figures 1 to 4B The following describes a common configuration for a photoelectric conversion device according to an exemplary embodiment. The photoelectric conversion device includes a single-photon avalanche diode (SPAD) pixel, which includes an avalanche photodiode (APD). Among the charge pairs generated in the avalanche diode, the conductivity type of the charge to be used as the signal charge is referred to as the first conductivity type. The first conductivity type refers to the conductivity type in which charges of the same polarity as the signal charge are considered the primary carriers. Additionally, the conductivity type opposite to the first conductivity type is referred to as the second conductivity type. The following description will be given as an example where the signal charge is an electron, the first conductivity type is N-type, and the second conductivity type is P-type; however, the signal charge can be a hole, the first conductivity type can be P-type, and the second conductivity type can be N-type.

[0043] When the signal charge is electrons, the signal is read from the cathode of the APD; when the signal charge is holes, the signal is read from the anode of the APD. Therefore, the cathode and anode of the APD have opposite relationships.

[0044] In this specification, a "plan view" refers to a view taken from a direction perpendicular to the light-incident surface of the semiconductor layer on which the photoelectric conversion element described below is arranged. A cross-section refers to a surface in a direction perpendicular to the light-incident surface of the semiconductor layer on which the photoelectric conversion element is arranged. In cases where the light-incident surface of the semiconductor layer appears rough under a microscope, the plan view is defined based on the macroscopically observed light-incident surface of the semiconductor layer.

[0045] First, the common configurations for the exemplary embodiments will be described.

[0046] Figure 1This is a diagram illustrating the configuration of a photoelectric conversion device 100 according to an exemplary embodiment of the present invention. The following description will use an example case where the photoelectric conversion device 100 is a stacked photoelectric conversion device. In other words, the description will be given using a photoelectric conversion device comprising two stacked substrates corresponding to an electrically connected sensor substrate 11 and a circuit substrate 21 as an example. However, the photoelectric conversion device is not limited to this. For example, the photoelectric conversion device may be a photoelectric conversion device in which components included in the sensor substrate 11 and components included in the circuit substrate (described below) are arranged in a common semiconductor layer. In the following description, a photoelectric conversion device in which components included in the sensor substrate 11 and components included in the circuit substrate are arranged in a common semiconductor layer will also be referred to as a non-stacked photoelectric conversion device.

[0047] The sensor substrate 11 includes a first semiconductor layer and a first wiring structure. The first semiconductor layer includes a photoelectric conversion element 102, which will be described below. The circuit substrate 21 includes a second semiconductor layer and a second wiring structure. The second semiconductor layer includes circuitry such as the signal processing circuitry 103, which will be described below. The photoelectric conversion device 100 includes a second semiconductor layer, a second wiring structure, a first wiring structure, and a first semiconductor layer stacked in the following order.

[0048] Figure 1 An example of a back-illuminated photoelectric conversion device is illustrated. This device receives light entering from a first surface and includes a circuit board disposed on a second surface opposite to the first surface. In the case where the photoelectric conversion device 100 is a non-stacked photoelectric conversion device, the surface on which signal processing circuitry is disposed is referred to as the second surface. In the case where the photoelectric conversion device 100 is a back-illuminated photoelectric conversion device, the first surface of the semiconductor layer opposite to the second surface serves as the light incident surface. In the case where the photoelectric conversion device 100 is a front-illuminated photoelectric conversion device, the second surface of the semiconductor layer serves as the light incident surface.

[0049] In the following description, sensor substrate 11 and circuit substrate 21 will be described as diced chips, but sensor substrate 11 and circuit substrate 21 are not limited to such chips. For example, each substrate can be a wafer. Alternatively, the substrates can be stacked in wafer state and then diced, or they can be diced into chips and then bonded by stacking the chips.

[0050] Pixel region 12 is arranged on sensor substrate 11, and circuit region 22 for processing the signal detected in pixel region 12 is arranged on circuit substrate 21.

[0051] Figure 2This is an example illustrating the arrangement of the sensor substrate 11. Pixels 101 are arranged in a two-dimensional array in a plan view and form pixel regions 12. Each pixel 101 includes a photoelectric conversion element 102, which includes an avalanche photodiode (hereinafter referred to as an APD).

[0052] Typically, pixel 101 is the pixel used to form an image. However, in the case of pixel 101 being used in a time-of-flight (TOF) sensor, it is not always necessary to form an image. That is, pixel 101 can be a pixel used to measure the time of light arrival and also used to measure the amount of light.

[0053] Figure 3 This is a configuration diagram of the circuit board 21. The circuit board 21 includes a signal processing circuit 103, a readout circuit 102, a control pulse generation unit 115, a horizontal scanning circuit unit 111, signal lines 113, and a vertical scanning circuit unit 110. The signal processing circuit 103 processes the signal pulses generated by the circuit board. Figure 2 The photoelectric conversion element 102 illustrated in the figure processes the charge converted by photoelectric conversion.

[0054] Figure 2 The photoelectric conversion element 102 illustrated in the figure and Figure 3 The signal processing circuit 103 illustrated in the figure is electrically connected via a connection wire provided for each pixel.

[0055] Vertical scanning circuit unit 110 receives control pulses supplied from control pulse generation unit 115 and supplies control pulses to each pixel. Logic circuitry such as shift registers or address decoders is used as vertical scanning circuit unit 110.

[0056] The control pulse generation unit 115 includes a signal generation unit 215, which generates a control signal P_CLK for the switch, which will be described below. As described below, the signal generation unit 215 generates a pulse signal for controlling the switch. Figure 4A As illustrated in the illustration, for example, the signal generation unit 215 can generate a common control signal P_CLK for multiple pixels in a pixel region, or as... Figure 4BAs illustrated, signal generation unit 215 can generate a control signal P_CLK for each pixel. When signal generation unit 215 generates a common pulse signal P_CLK, it generates the common control signal P_CLK in a manner that associates at least one of the period, number of pulses, and pulse width of the pulse signal P_EXP used to control the exposure time period with the exposure time period. When signal generation unit 215 controls the control signal P_CLK for each pixel, it can use both the input signal P_CLK_IN output from control pulse generation unit 115 and the signal P_EXP used to control the exposure time period to generate the control signal P_CLK. Control pulse generation unit 115 preferably includes, for example, a frequency divider circuit. This enables simple control and reduces the increase in the number of components.

[0057] The signal output from the photoelectric conversion element 102 of the pixel is processed by the signal processing circuit 103. A counter and a memory are provided in the signal processing circuit 103, and the digital value is stored in the memory.

[0058] The horizontal scanning circuit unit 111 inputs control pulses for sequentially selecting each column to the signal processing circuit 103 to read signals from the memory storing digital signals for each pixel.

[0059] For the selected column, a signal is output from the signal processing circuit 103 corresponding to the pixel selected by the vertical scanning circuit unit 110 to the signal line 113.

[0060] The signal output to signal line 113 is output to a recording unit or signal processing unit provided outside the photoelectric conversion device 100 via output circuit 114.

[0061] exist Figure 2 In this embodiment, the photoelectric conversion elements in the pixel region can be arranged in one dimension. The effects of this invention can be achieved even when the number of pixels is only one, and the case of only one pixel is also included in this invention. Nevertheless, if the photoelectric conversion device includes multiple pixels, the power reduction effect of this exemplary embodiment can be more easily obtained. It is not necessary to provide the functionality of a signal processing unit for each of all photoelectric conversion elements. For example, a signal processing unit can be shared by multiple photoelectric conversion elements, and signal processing can be performed sequentially.

[0062] like Figure 2 and Figure 3As illustrated, multiple signal processing circuits 103 are arranged in a region overlapping with the pixel region 12 in the plan view. Then, the vertical scanning circuit unit 110, the horizontal scanning circuit unit 111, the readout circuit 112, the output circuit 114, and the control pulse generation unit 115 are arranged in a manner that overlaps with the region defined by the ends of the sensor substrate 11 and the ends of the pixel region 12 in the plan view. In other words, the sensor substrate 11 includes the pixel region 12 and a non-pixel region arranged around the pixel region 12. Then, the vertical scanning circuit unit 110, the horizontal scanning circuit unit 111, the readout circuit 112, the output circuit 114, and the control pulse generation unit 115 are arranged in a region overlapping with the non-pixel region in the plan view.

[0063] The arrangement of signal line 113, readout circuit 112, and output circuit 114 is not limited to the following: Figure 3 The arrangements illustrated herein. For example, signal line 113 may be arranged to extend in the row direction, and readout circuitry 112 may be arranged at the end of the extended signal line 113.

[0064] Figure 4A and Figure 4B Each example includes the following descriptions. Figure 2 and Figure 3 An example of a block diagram of the equivalent circuit. Figure 4A This example illustrates an instance where multiple pixels jointly provide the signal generation unit 215. Figure 4B An example illustrating how the control signal P_CLK can be controlled for each pixel.

[0065] exist Figure 4A In this circuit, a photoelectric conversion element 102, including an APD 201, is provided on a sensor substrate 11, and other components are provided on a circuit board 21.

[0066] APD 201 generates charge pairs corresponding to incident light through photoelectric conversion. One of the two nodes of APD 201 is connected to an electric field line supplied with a driving voltage VL (first voltage). The other node of APD 201 is connected to an electric field line supplied with a driving voltage VH (second voltage), which is higher than the driving voltage VL supplied to the anode. Figure 4A and Figure 4B In this configuration, one node of APD 201 is the anode, and the other node is the cathode. A reverse bias voltage is supplied to the anode and cathode of APD 201 to enable it to perform avalanche multiplication. By causing this voltage to be supplied, the charge generated by the incident light induces avalanche multiplication, and an avalanche current is generated.

[0067] With a reverse bias voltage supplied, the APD operates in either Geiger mode or linear mode. In Geiger mode, the APD operates with a potential difference between the anode and cathode greater than the breakdown voltage. In linear mode, the APD operates with a potential difference between the anode and cathode close to the breakdown voltage, or equal to or less than the breakdown voltage.

[0068] An APD operating in Geiger mode will be referred to as a SPAD. For example, the drive voltage VL (first voltage) is -30V, and the drive voltage VH (second voltage) is 1V. The APD 201 can be operated in linear mode or in Geiger mode. It is preferable to use a SPAD because the potential difference is larger and the voltage withstand effect is more pronounced compared to an APD in linear mode.

[0069] Switch 202 is connected to a node between the power line supplied with the drive voltage VH and the anode and cathode of APD 201. Switch 202 then switches the resistance value between APD 201 and the power line supplied with the drive voltage VH. Preferably, switching the resistance value increases the resistance by ten times or more, more preferably by one hundred times or more. Hereinafter, decreasing the resistance value will also be referred to as turning on switch 202, and increasing the resistance value will also be referred to as turning off switch 202. Switch 202 functions as a quenching element. Switch 202 acts as a load circuit (quenching circuit) when the signal is amplified by avalanche multiplication, and has the function of suppressing avalanche multiplication by suppressing the voltage to be supplied to APD 201 (quenching operation). Switch 202 also has the function of returning the voltage to be supplied to APD 201 to the drive voltage VH by flowing a current corresponding to the voltage drop caused by the quenching operation (recharge operation).

[0070] Switch 202 may include, for example, a metal-oxide-semiconductor (MOS) transistor. Figure 4A and Figure 4B This example illustrates the case where switch 202 is a P-channel MOS (PMOS) transistor. A control signal P_CLK for switch 202, supplied from signal generation unit 215, is applied to the gate electrode of the MOS transistor included in switch 202. In this exemplary embodiment, the opening and closing of switch 202 are controlled by controlling the applied voltage to the gate electrode of switch 202.

[0071] The signal processing circuit 103 includes a waveform shaping unit 210, a counter circuit 211, and a selection circuit 212. Figure 4AIn the present invention, the signal processing circuit 103 includes a waveform shaping circuit 210, a counter circuit 211, and a selection circuit 212. However, in this specification, the signal processing circuit 103 may include at least one of the waveform shaping unit 210, the counter circuit 211, and the selection circuit 212.

[0072] The waveform shaping unit 210 outputs a pulse signal by shaping the potential change of the cathode of the APD 201 obtained during photon detection. The input-side node of the waveform shaping unit 210 is considered node A, and the output-side node is considered node B. The waveform shaping unit 210 changes the output potential of node B based on whether the input potential of node A is equal to or greater than a predetermined value, or lower than a predetermined value. For example, in... Figure 5 In this circuit, if the input potential of node A becomes high (equal to or greater than a predetermined threshold), the output potential of node B becomes low. Then, if the input potential of node A becomes lower than the predetermined threshold, the output potential of node B becomes high. For example, the inverter circuit is used as waveform shaping unit 210. Figure 4A An example is shown where an inverter circuit is used as waveform shaping unit 210, but a circuit in which multiple inverters are connected in series can be used, or another circuit with waveform shaping effect can be used.

[0073] Based on avalanche multiplication in APD 201, switch 202 can be used to perform quenching and recharge operations. However, in some cases, depending on the photon detection timing, the photon is not identified as an output signal. For example, when avalanche multiplication occurs in the APD, the input potential of node A becomes low, and the recharge operation is being performed. The determination threshold of waveform shaping operation 210 is generally set to a potential higher than the potential difference at which avalanche multiplication occurs in the APD. If a photon enters when the potential at node A falls below the determination threshold due to the recharge operation, and this potential is a potential in the APD at which avalanche multiplication can occur, avalanche multiplication occurs in the APD, and the voltage at node A drops. In other words, because the potential at node A drops below the determination threshold, the output potential of node B does not change even though the photon is detected. Therefore, although avalanche multiplication occurs, the photon stop is not identified as a signal. Especially under high illumination, because photons enter continuously within a short period of time, photons become difficult to identify as signals. For this reason, despite high illuminance, a discrepancy can easily arise between the actual number of incident photons and the number of output signals.

[0074] In contrast, by applying the control signal P_CLK to switch 202 between on and off, photons can also be identified as signals even when they continuously enter the APD within a short period of time. (Refer to...) Figure 5This will be used to describe an example where the control signal P_CLK is a pulse signal output according to a repetitive period. In other words, refer to... Figure 5 This describes a configuration in which the on / off state of switch 202 is switched at a predetermined clock frequency. Nevertheless, even if the pulse signal is not output in a repetitive cycle, the effect of suppressing increased power consumption of the photoelectric conversion device can be achieved.

[0075] The counter circuit 211 counts the number of pulse signals output from the waveform shaping unit 210 and stores the count value. When the control pulse pRES is supplied via the drive line 213, the number of pulse signals stored in the counter circuit 211 is reset.

[0076] Control pulse pSEL via Figure 4A The driving line 214 illustrated in the example (not shown) Figure 3 (Example illustration) From Figure 3 The vertical scanning circuit unit 110 illustrated herein is supplied to the selection circuit 212, and the electrical connection and disconnection between the counter circuit 211 and the signal line 113 are switched. The selection circuit 212 includes, for example, a buffer circuit for output signals. Figure 4A The example illustrates that the output signal OUT is a signal output from a pixel.

[0077] Electrical connections can be switched by arranging switches (such as transistors) between switch 202 and APD 201 or between photoelectric conversion element 102 and signal processing circuit 103. Similarly, the supply of drive voltage VH or drive voltage VL to photoelectric conversion element 102 can be electrically switched using switches (such as transistors).

[0078] In this exemplary embodiment, the configuration using counter circuit 211 has been described. However, the photoelectric conversion device 100 can obtain pulse detection timing by using a time-to-digital converter (hereinafter, TDC) and a memory instead of counter circuit 211. In this case, the generation timing of the pulse signal output from waveform shaping unit 210 is converted into a digital signal by the TDC. To measure the timing of the pulse signal, a control pulse pREF (reference signal) is transmitted via a drive line from... Figure 3 The vertical scanning circuit unit 110 illustrated in the diagram is supplied to the TDC. Based on the control pulse pREF, the TDC acquires a digital signal that indicates the input timing of the signal output from each pixel via the waveform shaping unit 210, as a relative time.

[0079] like Figure 4B As illustrated in the example, a signal generation unit 215 can be provided for each pixel. Figure 4B middle, Figure 4AThe waveform shaping unit 210, the circuit following the waveform shaping unit 210, and the signal generation unit illustrated in the diagram are omitted. Figure 4A The signal generation unit 215 is assumed to provide for each pixel. Figure 4B In this circuit, logic circuitry is provided within each pixel to determine whether a pulse signal is supplied to switch 202. A signal P_EXP for controlling the exposure time period and an input signal P_CLK_IN for controlling the control signal P_CLK are input to the logic circuitry. Then, an inverted signal is output. For example, when both the signal P_EXP for controlling the exposure time period and the input signal P_CLK_IN are low, a high-level signal is output as the control signal P_CLK. In other words, the switch is off. When both the signal P_EXP for controlling the exposure time period and the input signal P_CLK_IN are high, a low-level signal is output as the control signal P_CLK. In other words, the switch is on. Conversely, when either the signal P_EXP for controlling the exposure time period or the input signal P_CLK_IN is low, a high-level signal is output as the control signal P_CLK. In other words, the switch is off. In this way, it is desirable to control the switch for each pixel. Figure 4B When the circuit illustrated herein is used, as described in the second exemplary embodiment below, if the exposure time period P becomes low, the control signal P_CLK remains high. In other words, the switch is turned off.

[0080] Figure 5 This diagram schematically illustrates the relationship between the control signal P_CLK of the switch, the potential at node A, the potential at node B, and the output signal. In this exemplary embodiment, when the control signal P_CLK is high, the drive voltage VH is unlikely to be supplied to the APD; when the control signal P_CLK is low, the drive voltage VH is supplied to the APD. The high level of the control signal P_CLK is, for example, 1V, and the low level of the control signal P_CLK is, for example, 0V. When the control signal P_CLK is high, the switch is turned off; when the control signal P_CLK is low, the switch is turned on. The resistance value of the switch set when the control signal P_CLK is high becomes higher than the resistance value of the switch set when the control signal P_CLK is low. When the control signal P_CLK is high, because even if avalanche multiplication occurs in the APD, a recharge operation is unlikely to be performed, the potential supplied to the APD becomes equal to or less than the breakdown voltage of the APD. Therefore, the avalanche multiplication operation in APD is stopped.

[0081] like Figure 4A and Figure 4B As illustrated, it is preferable that switch 202 includes a single transistor, and that this single transistor is used to perform both quenching and recharging operations. With this configuration, the number of circuits can be reduced compared to using different circuit elements to perform the quenching and recharging operations. Particularly when a counter circuit is included for each pixel, and the SPAD signal is read out for each pixel, it is preferable to reduce the circuit area used for the switch in order to arrange the counter circuit, and the effect obtained by using switch 202, which includes a single transistor, becomes even more pronounced.

[0082] At time t1, the control signal P_CLK changes from high to low, the switch is turned on, and the APD recharging operation begins. The potential at the cathode of the APD thus becomes high. Then, the potential difference between the potentials applied to the anode and cathode of the APD becomes a state where avalanche multiplication can occur. The potential at the cathode is the same as the potential at node A. Therefore, when the potential at the cathode changes from low to high, at time t2, the potential at node A becomes equal to or greater than a predetermined threshold. At this time, the pulse signal output from node B reverses from high to low. Thereafter, a potential difference corresponding to (drive voltage VH - drive voltage VL) is applied to APD 201. The control signal P_CLK goes high, and the switch is turned off.

[0083] Next, if a photon enters APD 201 at time t3, avalanche multiplication occurs in APD 201, the avalanche multiplication current flows to switch 202, and the voltage at the cathode drops. In other words, the voltage at node A drops. If the voltage drop increases further and the potential difference applied to APD 201 decreases, the avalanche multiplication of APD 201 stops at time t2, and the voltage level at node A stops decreasing from a certain fixed value. If the voltage at node A falls below a predetermined threshold while the voltage at node A is decreasing, the voltage at node B changes from a low level to a high level. In other words, the portion of the output waveform at node A that exceeds the predetermined threshold undergoes waveform shaping performed by waveform shaping unit 210 and is output as a signal at node B. The signal is then counted by a counter circuit, which increments the count value of the counted signal output from the counter circuit by one least significant bit (LSB).

[0084] Photons enter the APD during the time interval between t3 and t4, but the switch is off, and the applied voltage to APD 201 does not have the potential difference that avalanche multiplication can occur. Therefore, the voltage level at node A will not exceed a predetermined threshold.

[0085] At time t4, the control signal P_CLK changes from high to low, and the switch is turned on. The current compensating for the voltage drop from the drive voltage VL flows to node A, and the voltage at node A returns to its original level. At this point, because the voltage at node A becomes equal to or greater than a predetermined threshold at time t5, the pulse signal at node B reverses from high to low.

[0086] At time t6, the voltage level at node A statistically stabilizes at its original level, and the control signal P_CLK changes from low to high. Therefore, the switch is turned off. Subsequently, the potential at each node and signal line also changes according to the control signal P_CLK and the arrival of photons, as described using times t1 to t6.

[0087] In the following, a photoelectric conversion device according to each exemplary embodiment will be described.

[0088] <First Exemplary Example>

[0089] Figures 6A to 6C This is a timing diagram illustrating the relationship between the exposure time period P and the control signal P_CLK according to the first exemplary embodiment. Figure 6A This is a diagram illustrating the pulse signal of the control signal P_CLK output when the exposure time period is exposure time period P1. Figure 6B This is a diagram illustrating the pulse signal of the control signal P_CLK output when the exposure time is longer than the exposure time P1 and the exposure time P2 is longer. Figure 6C This is a diagram illustrating the pulse signal of the control signal P_CLK output when the exposure time is longer than the exposure time P2 and is an exposure time P3.

[0090] In this exemplary embodiment, the exposure time period P refers to, for example, the period during which the mechanical or electronic shutter is open, and the non-exposure time period refers to, for example, the period during which the mechanical or electronic shutter is closed. Furthermore, the exposure time period P can be defined by adjusting the bias voltage applied to the APD 201 to change whether a photon signal can be acquired. The exposure time period P refers to the period during which the APD 201 is in an operable state and the APD and signal processing circuit are in a signal-readable state. Here, the state where the APD and signal processing circuit are in a signal-readable state refers to a state where avalanche multiplication can occur in the APD. It can also be said that the counter circuit is operating during the said time period. At this time, the period for quenching the APD (which is the state where the switch is turned off based on photon entry) constitutes part of the operable state. On the other hand, the periods during which light is blocked by the shutter, and the periods during which the APD is controlled in a manner where avalanche multiplication does not occur, regardless of whether photons enter, become non-exposure time periods.

[0091] like Figures 6A to 6C As illustrated in this exemplary embodiment, the pulse signal of the control signal P_CLK is changed according to the exposure time period P. A first exposure time period and a second exposure time period are adopted, the second exposure time period being different from the first exposure time period. The control signal is controlled in such a way that the value obtained by dividing the number of control signals P_CLK within the first exposure time period by the first exposure time period and multiplying the result by the first exposure time period is different from the value obtained by dividing the number of control signals P_CLK within the second exposure time period by the second exposure time period and multiplying the result by the first exposure time period. In this exemplary embodiment, because the switch 202 is a PMOS transistor, the number of control signals P_CLK refers to the number of off pulses within a predetermined exposure time period.

[0092] Furthermore, the control signal P_CLK is controlled in such a way that the average frequency of the control signal P_CLK during the first exposure time period differs from the average frequency of the control signal P_CLK during the second exposure time period, which is different from the first exposure time period, when compared in each unit time. Here, the average frequency of the control signal P_CLK during the exposure time period refers to the frequency obtained by uniformly averaging the pulse signals during the exposure time period. For example, if the pulse signals are densely distributed in the first half of the exposure time period and no pulse signals are distributed in the second half, the frequency adjusted in such a way that the pulse signals are evenly distributed over the entire time period refers to the average frequency of the control signal P_CLK during the exposure time period. Thus, in this exemplary embodiment, the control signal P_CLK is controlled in such a way that the average frequency during the first exposure time period and the average frequency during the second exposure time period differ when the average frequency is compared between the first and second exposure time periods. A unit time refers to the time during which at least two pulse signals of the control signal P_CLK are output.

[0093] exist Figures 6A to 6C In this process, the pulse signal of the control signal P_CLK is controlled in such a way that even if the exposure time period P changes, the number of pulses of the pulse signal within the exposure time period P remains the same. Figure 6A The number of pulses of the control signal P_CLK during the exposure time period P1 illustrated in the example is set to N. Similarly, in Figure 6B During the exposure time period P2 illustrated in the example, the number of pulses of the control signal P_CLK is set to N. Furthermore, similarly... Figure 6C During the exposure time period P3 illustrated in the example, the number of pulses of the control signal P_CLK is set to N.

[0094] The above configuration prevents an increase in power consumption per pixel. Furthermore, when the signal processing unit includes a counter circuit, it becomes possible to execute a clock drive that maintains an appropriate upper limit on the count.

[0095] In the following text, it will be in conjunction with Figures 7A to 7C The comparison configuration in the document is compared and a detailed description is provided. Figures 7A to 7C These are timing diagrams, each illustrating the relationship between the exposure time period P and the control signal P_CLK based on the comparison configuration. Figures 7A to 7C In, with Figures 6A to 6C Components similar to those in the [component name] are assigned to [component name]. Figures 6A to 6C Those numbers that are identical to the labels in the original text will have their descriptions omitted.

[0096] exist Figures 7A to 7CIn the comparison configuration illustrated in the example, the period of the control signal P_CLK remains the same even if the exposure time period changes. In this exemplary embodiment, because switch 202 is a PMOS transistor, the period of the control signal P_CLK refers to the time period from the falling edge of the pulse to the next falling edge. For example, the period of the control signal P_CLK is the same in both the case where the exposure time period is exposure time period P1 and the case where the exposure time period is exposure time period P2. Therefore, in the comparison configuration, if the exposure time period P changes, the number of pulses of the pulse signal within the exposure time period P changes. In this configuration, depending on the exposure time period, power consumption may increase involuntarily. Even if the clock frequency is increased in the subsequent signal processing circuit, the result is not reflected, and unnecessary power consumption may occur. For example, if the signal processing circuit is a counter circuit, the clock frequency at a value greater than the readable upper limit of the counter is not read as a signal. That is, at a value greater than the upper limit of the counter, even if the signal is read by performing a quenching operation and a recharge operation, the count value is not added to the counter circuit. Therefore, unnecessary power consumption occurs at a value greater than the upper limit of the counter. If the clock frequency is increased too much, the number of readable photons decreases, and the dynamic range may shrink.

[0097] In contrast, as mentioned above, by controlling the number of pulses of the control signal P_CLK according to the exposure time period, unnecessary power consumption can be reduced.

[0098] like Figures 6A to 6C As illustrated, the period of the control signal P_CLK changes according to the exposure time period. For example, the period of the control signal P_CLK during exposure time period P1 is shorter than the period of the control signal P_CLK during exposure time period P2. In this way, Figures 6A to 6C Even if the exposure time period changes like exposure time period P1, exposure time period P2, and exposure time period P3, the number of pulses of the control signal P_CLK is always controlled to be N. This configuration can reduce the increase in power consumption.

[0099] The number of pulses within the exposure time period can be set to any value. If the subsequent signal processing circuit is a counter circuit, the number of pulses can preferably be set to the upper limit of the counter circuit's count. This configuration can prevent unnecessary power consumption while preventing dynamic range degradation.

[0100] The first pulse width within exposure time period P1 and the first pulse width within exposure time period P2 are preferably the same. Here, the first pulse width refers to the time period during which switch 202 is turned on according to control signal P_CLK. In this exemplary embodiment, since switch 202 is a PMOS transistor, the first pulse width refers to the time period during which control signal P_CLK is at a low level (first level). As mentioned above, the time period during which control signal P_CLK is at a high level (second level) is the time period during which the switch is turned off and recharging is unlikely to be performed in the APD. In this specification, the time period during which control signal P_CLK remains at a low first level will be described as the "first pulse width," and the time period during which control signal P_CLK remains at a second level will be described as the "second pulse width." Figures 6A to 6C In the exposure time period P1, the first pulse width is the same as the first pulse width in the exposure time period P2, but the second pulse width in the exposure time period P1 is different from the second pulse width in the exposure time period P2.

[0101] Unlike other operations, the period during which the control signal P_CLK is low is the period during which the switch is turned on and the recharge operation is performed in the APD. If the period during which the control signal P_CLK is low is longer, the recharge operation may be performed multiple times. See reference... Figure 5 As described, when the potential at node A is below a predetermined threshold, the potential at node A decreases, the signal at node B is not reversed, and the signal may not be properly read out as a signal value. Therefore, by setting the time period during which the recharge operation is performed in the APD to a fixed time period even if the period of the pulse signal changes, the recharge operation is not performed multiple times during the period when the control signal P_CLK is low, and the number of undetectable photons can be reduced.

[0102] Figure 8 An example flowchart illustrating the operation of the photoelectric conversion device according to this exemplary embodiment is provided.

[0103] In step S1, the exposure time period and the number of pulses for the control signal P_CLK are set. In this example, the clock frequency of the control signal P_CLK is set. In step S2, image capture begins. In step S3, it is determined whether to change the exposure time period. This can be determined based on information from previously captured images (previous frame information). In the previous frame information, if the information obtained from the image is too bright, the exposure time period is shortened; if the information obtained from the image is too dark, the exposure time period is lengthened. Alternatively, the exposure time period can be switched manually or automatically.

[0104] If it is determined in step S3 that the exposure time period will be changed, then in step S4, it is determined whether to extend the exposure time period setting. If it is determined in step S3 that the exposure time period will be changed, the process continues to S4. If it is determined in step S3 that the exposure time period will not be changed, the process continues to step S7.

[0105] If it is determined in step S4 that the exposure time period will be extended, in step S5, the average clock frequency of the control signal P_CLK during the exposure time period is reduced. In this case, control is performed such that the number of pulses of the control signal P_CLK during the exposure time period remains unchanged compared to the number of pulses of the control signal P_CLK during the unchanged exposure time period. If it is determined in step S4 that the exposure time period will not be extended (will be shortened), in step S6, the average clock frequency of the control signal P_CLK during the exposure time period is set to a higher average clock frequency. Similarly, in this case, control is performed such that the number of pulses of the control signal P_CLK during the exposure time period remains unchanged compared to the number of pulses of the control signal P_CLK during the unchanged exposure time period.

[0106] After step S5 or S6, the process continues to step S7, where it is determined whether to terminate image capture. If it is determined in step S7 that image capture will terminate, image capture is terminated in step S8. If it is determined in step S7 that image capture will not terminate, the process returns to step S3, and the processes in steps S3 to S7 are repeated. Then, if it is determined in step S7 that image capture will terminate, image capture is terminated in step S8.

[0107] The operation can be performed according to the flowchart above.

[0108] Figures 9A to 9F This section provides an example illustrating the modification of a timing diagram. Figures 6A to 6C In this configuration, a pulse signal P_CLK is input at a fixed period, but the configuration is not limited to this. For example... Figures 9A to 9C As illustrated in the example, a pulse signal P_CLK can be input to change the pulse period. Figures 9A to 9C In this process, the period can be changed for each pulse signal, but it can also be changed for every three, four, or more pulse signals.

[0109] In addition, such as Figures 9D to 9FAs illustrated in the example, within the same time period as exposure time period P1, the number of pulses in exposure time period P2 and the number of pulses in exposure time period P3 can be the same as the number of pulses in exposure time period P1. More specifically, a configuration can be adopted in which the control signal P_CLK is continuously supplied to the switch during the first half of exposure time period P2, and the control signal P_CLK is not supplied during the second half of exposure time period P2. Similarly, in this case, if the number of pulses in exposure time period P2 is the same as the number of pulses in exposure time period P1, the effects of this exemplary embodiment can be obtained. Similarly, if the number of pulses in exposure time period P3 is the same as the number of pulses in exposure time period P1, the effects of this exemplary embodiment can be obtained.

[0110] <Second Exemplary Embodiment>

[0111] Figures 10A to 10C These are timing diagrams, each illustrating the relationship between the exposure time period P and the control signal P_CLK according to the second exemplary embodiment. Figure 10A This is a diagram illustrating the pulse signal of the control signal P_CLK output when the exposure time period is exposure time period P1. Figure 10B This is a diagram illustrating the pulse signal of the control signal P_CLK output when the exposure time is longer than the exposure time P1 and the exposure time P2 is longer. Figure 10C This is a diagram illustrating the pulse signal of the control signal P_CLK output when the exposure time is longer than the exposure time P2 and is an exposure time P3.

[0112] The photoelectric conversion device according to this exemplary embodiment differs from the first exemplary embodiment in that the photoelectric conversion device stops generating a pulse signal of control signal P_CLK at a timed interval when the exposure period transitions into the non-exposure period. Because, apart from this point and the key points described below, this exemplary embodiment is substantially similar to the first exemplary embodiment, components similar to those in the first exemplary embodiment are assigned the same reference numerals, and their descriptions are sometimes omitted.

[0113] In this exemplary embodiment, at the end of the exposure time period, the control signal P_CLK remains at a low level. That is, the switch remains in the off state. Then, at the beginning of the exposure time period, the control signal P_CLK goes high.

[0114] Since no photons enter the APD during the non-exposure period, it becomes unnecessary to control the switch on / off. Therefore, by avoiding changes to the control signal P_CLK used to control the switch on / off, power consumption caused by turning the switch on / off can be suppressed.

[0115] The end time of the exposure period can be controlled synchronously with the shutter speed.

[0116] In addition, such as Figures 10A to 10C As illustrated in the example, to reduce power consumption, it is desirable to stop the pulse signal of the control signal P_CLK synchronously with the end timing of the exposure period, but the stop timing can be slightly offset from the end timing of the exposure period.

[0117] According to this exemplary embodiment, similar to the first exemplary embodiment, the increase in power consumption can be suppressed. Furthermore, because the number of times the switch is turned on / off can be reduced compared to the first exemplary embodiment, the power consumption of the photoelectric conversion device can be further suppressed.

[0118] <Third Exemplary Example>

[0119] Reference Figures 11 to 1 3 describes the correction of the count value Nct obtained in the photoelectric conversion device according to the first exemplary embodiment or the second exemplary embodiment.

[0120] Figure 11 This diagram illustrates the relationship between the number of incident photons Nph and the count value Nct in each pixel of the photoelectric conversion device. Here, the number of incident photons Nph is the number of photons that actually enter each pixel during each exposure time period T (the number of incident photons). The count value Nct is the count value of the pulse signal output from the waveform shaping unit 210, which is counted by the counter circuit 211. Here, when the frequency of the control signal P_CLK is represented by f, the number of pulses of the control signal P_CLK during the exposure time period T is equal to f × T.

[0121] When the switch 202 of each pixel is controlled based on periodic pulses, the count value Nct of each pixel exhibits the following characteristics: Figure 11The property is indicated by curve A in the diagram. More specifically, the count value Nct increases with the increase of the number of incident photons Nph, and is counted up to the upper limit of the number of pulses f×T. Because a recharge operation is performed for one pulse of the control signal P_CLK, only one photon can be counted for one cycle of the control signal P_CLK. Therefore, in the case of multiple photons entering during one cycle of the control signal P_CLK, the second photon and subsequent photons in each cycle are not counted. Thus, in high-illuminance environments, the number of photons that are not counted even when they enter a pixel increases, and a difference appears between the count value Nct and the actual number of incident photons Nph.

[0122] In view of the foregoing, in this exemplary embodiment, a correction is performed to convert the count value Nct into a value equal to the actual number of incident photons Nph. The correction is performed by a correction circuit 118 connected to the circuit board 21. The correction circuit 118 may be provided externally to the photoelectric conversion device 100, such as... Figure 12 As illustrated in the illustration, it may also be provided internally in the photoelectric conversion device 100 (e.g., signal processing circuit 103). Figure 12 As illustrated in the illustration, an external output circuit 119 is also provided. The relationship between the count value Nct and the number of incident photons Nph is expressed by the following equation based on the natural logarithm.

[0123] Nct=f×T×(1-exp(-Nph / (f×T))) (1)

[0124] In other words, in the correction circuit 118, when the count value Nct, the frequency f of the pulse signal, and the length T of the exposure time period are considered as explanatory variables, and the number of incident photons Nph is considered as the target variable, the explanatory variables and the target variable are represented by a relational expression based on the natural logarithm.

[0125] The corrected count value Nct can be used Figure 11 The dashed line B indicates this. By performing correction, the count value indicated by curve A, which exhibits nonlinear properties relative to the number of incident photons, can be corrected to the count value indicated by the dashed line B, which has linearity relative to the number of incident photons.

[0126] Here, because the correction formula is based on the value of f×T, even if the value of the exposure time period T is defined for each frequency of the control signal P_CLK, as long as the combination of frequency f and exposure time period T is a combination that keeps f×T constant, the value of the count Nct relative to the number of incident photons Nph will not change.

[0127] Furthermore, when the two types of frequencies of the control signal P_CLK coexist during an exposure time period, the count value Nct can be corrected using the following equation: Nct=f1×T1×(1-exp(-Nph1 / (f1×T1)))+f2×T2×(1-exp(-Nph2 / (f2×T2)))(2)

[0128] Here, T1 represents the time period during which the pulse signal operates at a first frequency f1, and T2 represents the time period during which the pulse signal operates at a second frequency f2. T1 + T2 corresponds to the exposure time period T. Furthermore, Nph1 represents the number of incident photons within time period T1, and Nph2 represents the number of incident photons within time period T2. The number of incident photons, Nph1 and Nph2, can be expressed by the following equations.

[0129] Nph1=Nph×T1 / (T1+T2) (3)

[0130] Nph2=Nph×T2 / (T1+T2) (4)

[0131] In this way, the number of incident photons is determined by the ratio of the exposure time at each frequency to the total exposure time T.

[0132] Here, as Figure 13A and Figure 13B The illustrations will consider cases where multiple frequencies coexist within a single exposure time period. For example, such as... Figure 13A As illustrated, the pulse signal can be input in such a way that the frequency of the pulse signal input during the first half of the exposure time is frequency f1, and the frequency of the pulse signal input during the second half of the exposure time is frequency f2. Additionally, as... Figure 13B As illustrated in the example, two pulses of different frequencies can continue alternately. For each pair of pulse signals, a pulse signal of frequency f1 and a pulse signal of frequency f2 can continue alternately. Figure 13A and Figure 13B This example illustrates that two types of frequency pulse signals may coexist within the exposure time period, but three or more types of frequency pulse signals may coexist.

[0133] In this way, by using pulse signals of multiple frequencies that are mixed together during the exposure time, the slope of the count value under high illumination becomes larger compared to the case where only a low-frequency pulse signal is input. Therefore, even under high illumination, the gradient nature of the count value remains unchanged, and the dynamic range can be expanded compared to the case where the number of pulse signal frequency types is only one.

[0134] Furthermore, when the n types of frequencies of the control signal P_CLK exist mixed within the exposure time period, the correction equation is expressed by the following equation, where n is a natural number equal to or greater than 2.

[0135] Nct=f1×T1×(1-exp(-Nph1 / (f1×T1)))+f2×T2×(1-exp(Nph2 / (f2×T2)))+…+f n-1 ×T n-1 ×(1-exp(Nph n-1 / (f n-1 ×T n-1 )))+f n ×T n ×(1-exp(Nph n / (f n ×T n ))) (5)

[0136] The sum of the time intervals during which multiple frequency pulse signals are input equals the exposure time interval T. Furthermore, the number of incident photons during the time intervals during which multiple frequency pulse signals are input is expressed by the following equation.

[0137] Nph1=Nph×T1 / (T1+T2+…+T n-1 +T n (6)

[0138] Nph2=Nph×T2 / (T1+T2+…+T n-1 +T n (7)

[0139] Nph n-1 =Nph×T n-1 / (T1+T2+…+T n-1 +T n (8)

[0140] Nph n =Nph×T n / (T1+T2+…+T n-1 +T n (9)

[0141] The number of incident photons is determined by the ratio of the exposure time at each frequency to the total exposure time T.

[0142] The correction performed by correction circuit 118 is not limited to performing the correction represented by the above equation for each count value when appropriate. For example, correction circuit 118 may include a three-dimensional table that defines a combination of the exposure time period T, the frequency f of the pulse signal, and the count value Nct. By selecting the value closest to the measured value from the values ​​included in the table in correction circuit 118, the number of incident photons Nph can be roughly estimated. In this case, the values ​​in the table are set by a relational expression similar to the above equation, based on the natural logarithm corresponding to the combination of frequency f and exposure time period T.

[0143] The correction of the count value is not limited to this. By performing other types of corrections in sync with this correction by the correction circuit 118, the number of correction steps can be reduced. For example, a so-called gamma correction, which adjusts the brightness of the image formed based on the count value, can be performed when preparing for display on a monitor.

[0144] <Fourth Exemplary Example>

[0145] Figure 14 This is a block diagram illustrating the configuration of an optical detection system 1200 according to this exemplary embodiment. The optical detection system 1200 according to this exemplary embodiment includes a photoelectric conversion device 1204. Here, any of the photoelectric conversion devices described in the above exemplary embodiments can be used as the photoelectric conversion device 1204. The photoelectric detection system 1200 can be used, for example, as an image capture system. Specific examples of image capture systems include digital still cameras, digital video cameras, and surveillance cameras. Figure 14 An example is given in which a digital still camera is used as an optical inspection system 1200.

[0146] Figure 14 The illustrated optical inspection system 1200 includes a photoelectric conversion device 1204, a lens 1202, an aperture 1203, and a barrier 1201. The lens 1202 forms an optical image of the subject on the photoelectric conversion device 1204. The aperture 1203 is used to change the amount of light passing through the lens 1202, and the barrier 1201 is used to protect the lens 1202. The lens 1202 and the aperture 1203 serve as an optical system to converge light onto the photoelectric conversion device 1204. A shutter is arranged between the aperture 1203 and the photoelectric conversion device 1204. By opening and closing the shutter, the exposure time of the photoelectric conversion device is controlled.

[0147] The optical inspection system 1200 further includes a signal processing unit 1205, which processes the output signal from the photoelectric conversion device 1204. The signal processing unit 1205 performs signal processing operations on the input signal after performing various types of correction and compression on the input signal when necessary. The optical inspection system 1200 further includes a buffer memory unit 1206 and an external interface unit (external I / F unit) 1209. The buffer memory unit 1206 is used to temporarily store image data, and the external interface unit 1209 is used to communicate with an external computer or the like. The optical inspection system 1200 further includes a recording medium 1211 (such as a semiconductor memory) and a recording medium control interface unit (recording medium control I / F unit) 1210. The recording medium 1211 is used to record or read captured image data, and the recording medium control interface unit 1210 is used to perform recording on or read from the recording medium 1211. The recording medium 1211 can be incorporated into the optical inspection system 1200, or it can be detachably attached to the optical inspection system 1200. Furthermore, communication between the recording medium control I / F unit 1210 and the recording medium 1211, and communication from the external I / F unit 1209, can be performed wirelessly.

[0148] The optical inspection system 1200 further includes a general control / computing unit 1208 and a timing signal generation unit 1207. The general control / computing unit 1208 performs various types of calculations and controls the entire digital still camera. The timing signal generation unit 1207 outputs various timing signals to the photoelectric conversion device 1204 and the signal processing unit 1205. Here, the timing signals, etc., can be input from an external source. The optical inspection system 1200 only needs to include at least the photoelectric conversion device 1204 and the signal processing unit 1205. The signal processing unit 1205 processes the output signals from the photoelectric conversion device 1204. The timing signal generation unit 1207 can be mounted on the photoelectric conversion device. The general control / computing unit 1208 and the timing signal generation unit 1207 can be configured to perform some or all of the control functions of the photoelectric conversion device 1204.

[0149] The photoelectric conversion device 1204 outputs an image signal to the signal processing unit 1205. After performing predetermined signal processing on the image signal output from the photoelectric conversion device 1204, the signal processing unit 1205 outputs image data. The signal processing unit 1205 uses the image signal to generate an image. Additionally, the signal processing unit 1205 can perform distance measurement calculations on the signal output from the photoelectric conversion device 1204. The signal processing unit 1205 and the timing signal generation unit 1207 can be mounted on the photoelectric conversion device. That is, the signal processing unit 1205 and the timing signal generation unit 1207 can be provided on a substrate on which pixels are arranged, or they can be provided on another substrate. By using the photoelectric conversion devices according to each of the exemplary embodiments described above to form an image capture system, an image capture system capable of acquiring higher quality images can be realized.

[0150] <Fifth Exemplary Example>

[0151] Figure 15 This is a block diagram illustrating an example configuration of a distance image sensor, which is an electronic device using the photoelectric conversion device described in the exemplary embodiments above.

[0152] like Figure 15 As illustrated, the distance image sensor 401 includes an optical system 407, a photoelectric conversion device 408, an image processing circuit 404, a monitor 405, and a memory 406. The distance image sensor 401 can then acquire a distance image corresponding to the distance to the subject by receiving light (modulated light or pulsed light) that has been projected from the light source device 409 toward the subject and reflected onto the front surface of the subject.

[0153] The optical system 407 includes one or more lenses and forms an image on the light-receiving surface (sensor portion) of the photoelectric conversion device 408 by guiding image light (incident light) from the subject onto the photoelectric conversion device 408.

[0154] According to any of the above exemplary embodiments, the photoelectric conversion device is used as photoelectric conversion device 408, and the distance signal indicating the distance obtained from the light receiving signal output from the photoelectric conversion device 408 is supplied to the image processing circuit 404.

[0155] The image processing circuit 404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 408. The distance image (image data) obtained through image processing is then supplied to the monitor 405 and displayed thereon, or supplied to the memory 406 and stored (recorded) therein.

[0156] By applying the photoelectric conversion device described above, the distance image sensor 401 with the above configuration can acquire a more accurate distance image, for example, by enhancing the characteristics of the pixels.

[0157] <Sixth Exemplary Example>

[0158] The technology disclosed herein can be applied to various products. For example, the technology disclosed herein can be applied to endoscope operating systems.

[0159] Figure 16 This is a diagram illustrating an example of a schematic configuration of an endoscope operating system to which the technology (the technology) according to this disclosure can be applied.

[0160] Figure 16 This illustration shows an operator (doctor) 1131 performing surgery on a patient 1132 lying on a hospital bed 1133 using an endoscope operating system 1003. Figure 16 As illustrated, the endoscope operating system 1003 includes an endoscope 1100, surgical instruments 1110, and a trolley 1134, the trolley 1134 being equipped with various devices for endoscope operation.

[0161] Endoscope 1100 includes a lens tube 1101 and a camera head 1102. The lens tube 1101 has a region extending a predetermined length from the distal end into a body cavity of the patient 1132, and the camera head 1102 is connected to the proximal end of the lens tube 1101. Figure 16 In the example illustrated, an endoscope 1100 is illustrated as a so-called rigid observation instrument comprising a rigid lens tube 1100, but the endoscope 1100 may be configured as a so-called flexible observation instrument comprising a flexible lens tube.

[0162] An opening into which the objective lens is fitted is provided at the distal end of the lens barrel 1101. A light source device 1139 is connected to the endoscope 1100. Light generated by the light source device 1139 is guided to the distal end of the lens barrel 1101 by a light guide extending inside the lens barrel 1101, and is emitted via the objective lens onto the target of observation in the body cavity of the patient 1132. The endoscope 1100 can be a direct-viewing endoscope, or it can be an oblique-viewing endoscope or a lateral-viewing endoscope.

[0163] An optical system and a photoelectric conversion device are provided inside the camera head 1102. Reflected light (observation light) from the observed target is focused by the optical system onto the photoelectric conversion device. The observation light is photoelectrically converted by the photoelectric conversion device, generating an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The photoelectric conversion device according to any of the above exemplary embodiments can be used as the photoelectric conversion device. The image signal is sent as raw data to the camera control unit (CCU) 1135.

[0164] The CCU 1135 includes a central processing unit (CPU) or a graphics processing unit (GPU) and provides comprehensive control over the operation of the endoscope 1100 and the display device 1136. Furthermore, the CCU 1135 receives image signals from the camera head 1102 and performs various types of image processing on the image signals for displaying an image based on the image signals, such as, for example, image processing (de-mosaicing).

[0165] Based on the control from CCU 1135, display device 1136 displays an image based on an image signal that has undergone image processing by CCU 1135.

[0166] The light source device 1139 includes a light source, such as, for example, a light-emitting diode (LED), and supplies radiant light for capturing images of the surgical site to the endoscope 1100.

[0167] Input device 1137 is an input interface for endoscope operating system 1003. Users can input various types of information and commands into endoscope operating system 1003 via input device 1137.

[0168] The processing tool control device 1138 controls the drive of the energy processing tool 1112 for burning or cutting tissue or sealing blood vessels.

[0169] The light source device 1139, which supplies radiant light for capturing images of the surgical site to the endoscope 1100, includes, for example, an LED, a laser light source, or a white light source comprising a combination of these. When the white light source comprises a combination of RGB laser light sources, the white balance of the captured image can be adjusted within the light source device 1139 because the output intensity and timing of each color (each wavelength) can be controlled more accurately. Furthermore, in this case, by emitting laser light from each RGB laser source onto the observation target in a time-division manner and controlling the drive of the image sensor of the camera head 1102 in sync with the emission timing, images corresponding to each of the RGB sources can also be captured in a time-division manner. According to this method, color images can be obtained without providing a color filter in the image sensor.

[0170] Furthermore, the drive of the light source device 1139 can be controlled in such a way that the intensity of the light to be output is changed at predetermined intervals. By using time-division multiplexing to control the drive of the image sensor of the camera head 1102 in time-synchronized with the change in light intensity, and by combining the images, high dynamic range images without underexposure or overexposure can be produced.

[0171] The light source device 1139 can be configured to supply light in a predetermined wavelength band suitable for specific light observation. In special light observation, for example, the wavelength dependence of light absorption in body tissue is utilized. Specifically, by emitting light in a narrower band than the radiation light (i.e., white light) used in ordinary observation, an image of a predetermined tissue (such as blood vessels in the superficial portion of a mucosa) is captured with high contrast. Alternatively, in special light observation, fluorescence observation can be performed to obtain an image using fluorescence generated by emitting excitation light. In fluorescence observation, fluorescence from body tissue can be observed by emitting excitation light onto the body tissue, or a fluorescence image can be obtained by locally injecting a reagent (such as indocyanine green (ICG)) into the body tissue and emitting excitation light corresponding to the fluorescence wavelength of the reagent onto the body tissue. The light source device 1139 can be configured to supply narrow-band light and / or excitation light suitable for such special light observation.

[0172] <Seventh Exemplary Example>

[0173] Reference Figure 17A , Figure 17B and Figure 18 To describe the optical detection system and movable body according to this exemplary embodiment. Figure 17A and Figure 17B This is a schematic diagram illustrating an example configuration of an optical detection system and a movable body according to this exemplary embodiment. Figure 18 This is a flowchart illustrating the operation of an optical inspection system according to this exemplary embodiment. In this exemplary embodiment, an in-vehicle camera will be described as an example of an optical inspection system.

[0174] Figure 17A and Figure 17BAn example is illustrated of a vehicle system and an optical inspection system installed in the vehicle system to perform image capture. The optical inspection system 1301 includes a photoelectric conversion device 1302, an image preprocessing unit 1315, an integrated circuit 1303, and an optical system 1314. The optical system 1314 forms an optical image of a subject on the photoelectric conversion device 1302. The photoelectric conversion device 1302 converts the optical image of the subject formed by the optical system 1314 into an electrical signal. The photoelectric conversion device 1302 is a photoelectric conversion device of any of the exemplary embodiments described above. The image preprocessing unit 1315 performs predetermined signal processing on the signal output from the photoelectric conversion device 1302. The function of the image preprocessing unit 1315 can be incorporated into the photoelectric conversion device 1302. In the optical inspection system 1301, at least two sets are provided, each set including the optical system 1314, the photoelectric conversion device 1302, and the image preprocessing unit 1315, and the output of the image preprocessing unit 1315 of each set is input to the integrated circuit 1303.

[0175] Integrated circuit 1303 is an integrated circuit intended for use in an image capture system and includes an image processing unit 1304 with a memory 1305, an optical distance measurement unit 1306, a distance measurement calculation unit 1307, an object recognition unit 1308, and an anomaly detection unit 1309. The image processing unit 1304 performs image processing, such as development processing and defect correction, on the output signal of the image preprocessing unit 1315. The memory 1305 is the main storage for the captured image and stores the defect locations of the captured pixels. The optical distance measurement unit 1306 performs focusing and distance measurement of the subject. The distance measurement calculation unit 1307 calculates distance measurement information from multiple image data acquired through multiple photoelectric conversion devices 1302. The object recognition unit 1308 identifies the subject, such as a vehicle, road, sign, or person. If the anomaly detection unit 1309 detects an anomaly in the photoelectric conversion device 1302, the anomaly detection unit 1309 sends an alarm indicating the anomaly to the main control unit 1313.

[0176] Integrated circuit 1303 can be implemented through specially designed hardware, through software modules, or through a combination of these. Alternatively, integrated circuit 1303 can be implemented through a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), or through a combination of these.

[0177] The main control unit 1313 comprehensively controls the operation of the optical detection system 1301, vehicle sensor 1310, control unit 1320, etc. Alternatively, the following method can be used, in which the main control unit 1313 is not included, and the optical detection system 1301, vehicle sensor 1310, and control unit 1320 each include a communication interface, and the optical detection system 1301, vehicle sensor 1310, and control unit 1320 each perform the transmission and reception of control signals via a communication network (e.g., the Controller Area Network (CAN) standard).

[0178] Integrated circuit 1303 has the function of receiving control signals from main control unit 1313 through its own control unit, or sending control signals and setting values ​​to photoelectric conversion device 1302.

[0179] The optical detection system 1301 is connected to the vehicle sensor 1310 and can detect the vehicle's operating status (such as vehicle speed, yaw rate, or steering angle) and the external environment of the vehicle, as well as the status of other vehicles and obstacles. The vehicle sensor 1310 also functions as a distance information acquisition unit, acquiring distance information indicating the distance to a target object. The optical detection system 1301 is also connected to the driver support control unit 1311, which performs various types of driver support functions, such as automatic steering, automatic detour, and collision avoidance. Specifically, regarding the collision determination function, based on the detection results of the optical detection system 1301 and the vehicle sensor 1310, a collision with another vehicle or obstacle is estimated and determined. In this configuration, if a collision is estimated, avoidance control is executed, and when a collision occurs, safety devices are activated.

[0180] The optical detection system 1301 is also connected to an alarm device 1312, which alerts the driver based on the determination results obtained by the collision determination unit. For example, if the determination results obtained by the collision determination unit indicate a high probability of collision, the main control unit 1313 performs vehicle controls to avoid a collision or reduce damage by braking, releasing the accelerator, or suppressing engine output. The alarm device 1312 alerts the user by emitting an alarm (such as a sound), displaying a warning message on a display unit screen of the vehicle navigation system or dashboard, or vibrating the seat belt or steering wheel.

[0181] In this exemplary embodiment, the optical detection system 1301 captures images of the vehicle's surroundings, such as, for example, the front or rear side. Figure 17B An example of the arrangement of the optical inspection system 1301 for capturing images of the front side of a vehicle is illustrated.

[0182] Two photoelectric conversion devices 1302 are arranged in the front of the vehicle 1300. Specifically, in order to obtain distance information between the vehicle 1300 and the target object and to determine the probability of a collision, it is preferable that the two photoelectric conversion devices 1302 are arranged symmetrically with respect to an axis of symmetry corresponding to the centerline of the vehicle 1300's direction of travel or external form (e.g., vehicle width). Furthermore, the photoelectric conversion devices 1302 are preferably arranged in such a way that they do not obstruct the driver's field of vision when the driver visually inspects the exterior of the vehicle 1300 from the driver's seat. The alarm device 1312 is preferably arranged in a manner that allows easy access to the driver's field of vision.

[0183] Next, refer to Figure 18 This describes the fault detection operation of the photoelectric conversion device 1302 in the optical inspection system 1301. The fault detection operation of the photoelectric conversion device 1302 is based on... Figure 18 The steps S1410 to S1480 illustrated in the example are performed.

[0184] Step S1410 is a step for setting up the photoelectric conversion device 1302. More specifically, settings for the operation of the photoelectric conversion device 1302 are sent from outside the optical detection system 1301 (e.g., the main control unit 1313) or inside the optical detection system 1301, and image capture operation and fault detection operation of the photoelectric conversion device 1302 are started.

[0185] Subsequently, in step S1420, a pixel signal is acquired from the valid pixel. Additionally, in step S1430, the output value of the fault detection pixel, provided for fault detection, is acquired. The fault detection pixel is similar to the valid pixel and includes a photoelectric conversion element. A predetermined voltage is written to the photoelectric conversion element. The fault detection pixel outputs a signal corresponding to the voltage written to the photoelectric conversion element. The processes in steps S1420 and S1430 can be performed in reverse order.

[0186] Subsequently, in step S1440, it is determined whether the expected output value and the actual output value of the fault detection pixel are equal. If, as a result of the equality determination in step S1440, the expected output value and the actual output value are equal, the process continues to step S1450. In step S1450, it is determined that the image capture operation was performed normally, and the process continues to step S1460. In step S1460, the pixel signals of the scanned rows are sent to memory 1305 and stored. Thereafter, the process returns to step S1420 and continues the fault detection operation. On the other hand, if, as a result of the equality determination in step S1440, the expected output value and the actual output value are not equal, the process continues to step S1470. In step S1470, it is determined that the image capture operation is abnormal, and an alarm is issued to the main control unit 1313 or the alarm device 1312. The alarm device 1312 displays on the display unit that an abnormality has been detected. Subsequently, in step S1480, the photoelectric conversion device 1302 is stopped, and the operation of the optical detection system 1301 is terminated.

[0187] In this exemplary embodiment, an example of processing each line of the loop flowchart has been illustrated, but processing can be performed on every few lines of the loop flowchart, or a fault detection operation can be performed on each frame. The alarm issued in step S147 can be transmitted to the outside of the vehicle via a wireless network.

[0188] Furthermore, while this exemplary embodiment has described control performed in a manner that avoids collision with another vehicle, the optical detection system 1301 can also be applied to control that performs automatic operation by following another vehicle, or to control that performs automatic operation without deviating from its lane. In addition to vehicles such as automobiles, the optical detection system 1301 can be applied to mobile bodies (mobile devices) such as ships, aircraft, or industrial robots. Moreover, besides mobile bodies, the optical detection system 1301 can also be applied to devices that widely utilize object recognition, such as intelligent transportation systems (ITS).

[0189] The photoelectric conversion device according to an exemplary embodiment of the present invention can be configured to further acquire various types of information, such as distance information.

[0190] <Eighth Exemplary Example>

[0191] Figure 19AThe illustration describes glasses 1600 (smart glasses) according to an application example. Glasses 1600 includes a photoelectric conversion device 1602. The photoelectric conversion device 1602 is the photoelectric conversion device described in any of the exemplary embodiments described above. A display device including a light-emitting device (such as an organic light-emitting diode (OLED) or LED) may be provided on the back side of the lens 1601. The number of photoelectric conversion devices 1602 may be one or more. Furthermore, multiple types of photoelectric conversion devices can be used in combination. The arrangement position of the photoelectric conversion devices 1602 is not limited to... Figure 19A The location of the example is shown in the text.

[0192] The eyeglasses 1600 further include a control device 1603. The control device 1603 serves as a power source for supplying power to the photoelectric conversion device 1602 and the aforementioned display device. The control device 1603 also controls the operation of the photoelectric conversion device 1602 and the display device. An optical system is formed in the lens 1601 to converge light onto the photoelectric conversion device 1602.

[0193] Figure 19B The following illustration describes glasses 1610 (smart glass) according to an application example. Glasses 1610 includes a control device 1612, which is equipped with a photoelectric conversion device equivalent to photoelectric conversion device 1602 and a display device. An optical system is formed in lens 1611 for projecting light emitted from the photoelectric conversion device and display device in the control device 1612, and an image is projected onto lens 1611. The control device 1612 serves as a power source for supplying power to the photoelectric conversion device and display device, and controls the operation of the photoelectric conversion device and display device. The control device may include a gaze detection unit for detecting the wearer's gaze. Infrared light can be used for gaze detection. An infrared light emitting unit emits infrared light onto the eyeball of a user looking at the displayed image. An imaging unit including a light receiving element detects the reflected light of the emitted infrared light that has been reflected from the eyeball. Thus, a captured image of the eyeball is obtained. By including a light reduction unit for reducing the light emitted from the infrared light emitting unit to the display unit in a planar image, image quality degradation is suppressed.

[0194] The user's gaze is detected on the displayed image from an image captured by the eye using infrared light. Any known method can be applied to gaze detection using an image captured by the eye. As an example, a gaze detection method based on Purkinje images obtained by reflecting radiated light onto the cornea can be used.

[0195] More specifically, gaze detection processing based on central pupillary corneal reflection is performed. By using central pupillary corneal reflection, an eye vector representing the direction (rotation angle) of the eyeball is calculated based on the pupil image and the Purkinje image included in the captured image of the eyeball, thus detecting the user's gaze.

[0196] The display device of this exemplary embodiment may include a photoelectric conversion device having a light receiving element, and the displayed image on the display device may be controlled based on the user's gaze information from the photoelectric conversion device.

[0197] Specifically, in a display device, a first visual field and a second visual field besides the first are determined based on gaze information. The first and second visual fields can be determined by the display device's control unit, or they can be received from an external control unit. Within the display area of ​​the display device, the display resolution of the first visual field can be controlled to be higher than that of the second visual field. In other words, the resolution of the second visual field can be lower than that of the first visual field.

[0198] Furthermore, the display area includes a first display area and a second display area different from the first display area. Based on gaze information, a high-priority area can be determined from the first and second display areas. The first and second display areas can be determined by the control device of the display device, or they can be received from an external control device. The resolution of the high-priority area can be controlled to be higher than the resolution of other areas. In other words, the resolution of the relatively low-priority area can be set to a low resolution.

[0199] Artificial intelligence (AI) can be used to determine a primary visual field and areas of high priority. The AI ​​can be a model configured to estimate the angle of gaze and the distance to a target object present at the end of the gaze using training data from images of the eye, including images of the eye and the actual direction the eye is gazing in those images. The AI ​​program can be included in a display device, in a photoelectric conversion device, or in an external device. In the case where the external device includes the AI ​​program, the AI ​​program is transmitted to the display device via communication.

[0200] With display control performed based on visual detection, the present invention can preferably be applied to smart glasses that further include a photoelectric conversion device for capturing external images. The smart glasses can display external information acquired through image capture in real time.

[0201] <Other exemplary embodiments>

[0202] Exemplary embodiments have been described previously, but the present invention is not limited to these exemplary embodiments, and various changes and modifications can be made. Furthermore, the exemplary embodiments can be applied to each other.

[0203] This invention is not limited to the above embodiments, and various changes and modifications can be made within the spirit and scope of this invention. Therefore, in order to inform the public of the scope of this invention, the following claims are made.

[0204] This application claims priority to Japanese Patent Application No. 2021-001441, filed January 7, 2021, and Japanese Patent Application No. 2021-207158, filed December 21, 2021, which are hereby incorporated herein by reference.

Claims

1. A photoelectric conversion device, comprising: Pixels, the pixels including: An avalanche photodiode, the avalanche photodiode comprising an anode and a cathode; A switch, connected between a power line to which a drive voltage will be applied and the anode or the cathode, and configured to receive a pulse signal for controlling the switching of the switch; and A signal processing circuit, comprising a counter circuit connected to the avalanche photodiode and configured to output an output signal. The value obtained by dividing the number of pulse signals within the first exposure time period by the first exposure time period is different from the value obtained by dividing the number of pulse signals within the second exposure time period by the second exposure time period, where the length of the second exposure time period is different from the length of the first exposure time period. The first exposure time period and the second exposure time period are respectively the time periods from the timing of the exposure control signal input to the pixel changing to the first level to the timing of the exposure control signal changing to the second level, and The exposure control signal is different from the pulse signal.

2. The photoelectric conversion device according to claim 1, wherein the pulse signal is a signal with a repetitive cycle.

3. The photoelectric conversion device according to claim 1 or 2, wherein the number of pulse signals in the first exposure time period and the number of pulse signals in the second exposure time period are the same.

4. The photoelectric conversion device according to claim 1 or 2, The first exposure time period is shorter than the second exposure time period, and The period of the pulse signal during the first exposure time period is shorter than the period of the pulse signal during the second exposure time period.

5. The photoelectric conversion device according to claim 1 or 2, wherein the first pulse width of the pulse signal at the first level during the first exposure time period and the first pulse width of the pulse signal at the first level during the second exposure time period are the same.

6. The photoelectric conversion device according to claim 5, wherein the second pulse width of the pulse signal in the first exposure time period at the second level and the second pulse width of the pulse signal in the second exposure time period at the second level are different.

7. The photoelectric conversion device according to claim 1 or 2, wherein the switch is used as a quenching element.

8. The photoelectric conversion device according to claim 1 or 2, The switch mentioned above is a metal-oxide-semiconductor (MOS) transistor. One node of the switch is connected to the cathode of the avalanche photodiode. The other node of the switch is connected to the power line, and The pulse signal is supplied to the gate electrode of the switch.

9. The photoelectric conversion device according to claim 1 or 2, wherein the signal processing circuit includes a waveform shaping unit. The waveform shaping unit is connected to the anode or the cathode, and The signal output from the waveform shaping unit is input to the counter circuit.

10. The photoelectric conversion device according to claim 9, wherein the number of pulse signals during the first exposure time period is equal to the upper limit of the counter circuit.

11. The photoelectric conversion device according to claim 9, further comprising a correction circuit, The count value output from the counter circuit is input to the correction circuit.

12. The photoelectric conversion device according to claim 11, wherein, In the correction circuit, when the count value, the frequency of the pulse signal during the first exposure time period, and the length of the first exposure time period are considered as explanatory variables, and the number of incident photons is considered as the target variable, the explanatory variables and the target variable are represented by a relational expression based on the natural logarithm.

13. The photoelectric conversion device according to claim 11 or 12, wherein, In response to the input of the count value, the correction circuit outputs the number of incident photons, Nph, which satisfies the following equation: Nct = f × T × (1 - exp(-Nph / (f × T))), The count value is represented by Nct, the number of incident photons is represented by Nph, the frequency of the pulse signal during the first exposure time period is represented by f, and the first exposure time period is represented by T.

14. The photoelectric conversion device according to claim 11, wherein, In response to the input of the count value, the correction circuit outputs the number of incident photons, Nph, which satisfies the following equation: Nct = f1 × T1 × (1 - exp(-Nph1 / (f1 × T1))) + f2 × T2 × (1 - exp(-Nph2 / (f2 × T2))) + … + f n-1 × T n-1 × (1 - exp(-Nph n-1 / (f n-1 × T n-1 ))) + f n × T n × (1 - exp(-Nph n / (f n × T n ))), The pulse signal mentioned above includes n types of frequencies. The first frequency of the pulse signal is denoted by f1, the second frequency by f2, and the (n-1)th frequency by f... n-1 The nth frequency is represented by f. n Let n be a natural number equal to or greater than 2, and n be a natural number equal to or greater than 2. The time period during which the frequency of the pulse signal is the first frequency f1 is denoted by T1, the time period during which the frequency of the pulse signal is the second frequency f2 is denoted by T2, and the time period during which the frequency of the pulse signal is the (n-1)th frequency f1 is denoted by T2. n-1 The time period is represented by T. n-1 This indicates that the frequency of the pulse signal is the nth frequency f. n The time period is represented by T. n express.

15. The photoelectric conversion device according to claim 1 or 2, further comprising a signal generation unit, The pulse signal is output from the signal generation unit and input to the switch. in, Outside of the first exposure time period and the second exposure time period, the signal generation unit does not generate the pulse signal.

16. The photoelectric conversion device according to claim 1 or 2, wherein the plurality of said avalanche photodiodes are arranged in a two-dimensional array in a plan view.

17. The photoelectric conversion device of claim 1, wherein the pixel further comprises logic circuitry configured to receive the exposure control signal and the input clock signal, and to output a pulse signal for controlling the switching of the switch based on both the exposure control signal and the input clock signal.

18. An optical detection system, comprising: The photoelectric conversion device according to any one of claims 1 to 17; as well as A signal processing unit is configured to process the signal output by the photoelectric conversion device.

19. An optical detection system, comprising: The photoelectric conversion device according to any one of claims 1 to 17; A signal processing unit configured to process the signal output by the photoelectric conversion device; as well as A shutter, configured to control the incidence of light onto the photoelectric conversion device. The first exposure time period and the second exposure time period are the time periods during which the shutter is opened.

20. A movable body, comprising: The photoelectric conversion device according to any one of claims 1 to 17; as well as A distance information acquisition unit, configured to acquire distance information indicating the distance to a target object from distance measurement information based on a signal from the photoelectric conversion device, the movable body further comprising: A control unit configured to control the movable body based on the distance information.

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