Photoelectric conversion device, photoelectric conversion system

Abstract

To accelerate measurement of the distance from a photoelectric conversion device to a measurement object.SOLUTION: A photoelectric conversion device has: a photoelectric conversion unit; a light quantity value holding unit that holds light quantity values based on signal charges generated in a first exposure period and a second exposure period different in at least one of a start timing and an end timing from the first exposure period; a comparison unit that compares the light quantity value based on the signal charges generated in the first exposure period and the light quantity value based on the signal charges generated in the second exposure period; and a control unit that, based on a result of comparison performed by the comparison unit, controls to set a third exposure period and a fourth exposure period different in at least one of a start timing and an end timing from the third exposure period. The third exposure period and the fourth exposure period is shorter than at least one of the first exposure period and the second exposure period.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a photoelectric conversion device and a photoelectric conversion system. [Background technology]

[0002] The TOF (Time of Flight) method is often used to measure the distance to a measurement object. In this TOF method, light is emitted from a light source and the reflected light reflected by the measurement object is detected. The TOF method then measures the distance to the measurement object by measuring the time difference between the timing at which the light is emitted and the timing at which the reflected light is detected. Patent Document 1 discloses a TOF distance measuring device using a Single Photon Avalanche Diode (SPAD), in which photocharges resulting from a single photon undergo avalanche multiplication in the PN junction region of a semiconductor region constituting a photoelectric conversion unit. Patent Document 1 also describes distance measurement using a time gate method in which a pulse signal having a width on the order of picoseconds to microseconds is used to quickly switch between a state in which a photon signal incident on the SPAD is detected (exposed state) and a state in which it is not detected (non-exposed state). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2017 / 0052065 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, in order to measure the time distribution of the detected light with high accuracy, it is necessary to scan the relative difference between the time gate timing and the light emission timing at short intervals within a time range corresponding to a predetermined distance measurement range. This increases the time required for each distance measurement, making it difficult to increase the speed of measuring the distance from the photoelectric conversion device to the measurement object. [Means for solving the problem]

[0005] According to one aspect, a photoelectric conversion device includes: Avalanche photodiode and, a counter circuit for counting the signal avalanche-multiplied by the avalanche photodiode; The exposure device includes a light quantity value holding unit that holds a light quantity value based on signal charges generated in a first exposure period and a second exposure period that differs from the first exposure period in at least one of start timing and end timing; a comparison unit that compares a light quantity value based on the signal charges generated in the first exposure period with a light quantity value based on the signal charges generated in the second exposure period; and a control unit that controls, based on a comparison result of the comparison unit, to set a third exposure period and a fourth exposure period that differs from the third exposure period in at least one of start timing and end timing, wherein the third exposure period and the fourth exposure period are shorter than at least one of the first exposure period and the second exposure period.

[0006] According to one aspect, a photoelectric conversion device includes: Avalanche photodiode and, a counter circuit for counting the signal avalanche-multiplied by the avalanche photodiode; The exposure control device includes a light quantity value storage unit that stores a light quantity value based on signal charges obtained by incident light during a first exposure period and a second exposure period that differs from the first exposure period in at least one of the start timing and end timing, and a comparison unit that compares the light quantity value obtained during the first exposure period with the light quantity value obtained during the second exposure period, and a control unit that controls a third exposure period and a fourth exposure period according to the comparison result of the comparison unit. [Effects of the Invention]

[0007] According to the present invention, the distance from the photoelectric conversion device to the object to be measured can be measured at higher speed than in Patent Document 1. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an example of a photoelectric conversion device according to Embodiment 1. [Figure 2] 1 is a timing diagram showing exposure patterns according to a comparative example and embodiment 1. [Figure 3]Block diagram of a unit pixel according to the first embodiment [Figure 4] Pixel driving timing diagram according to the first embodiment [Figure 5] Block diagram of a unit pixel according to the second embodiment [Figure 6] Pixel driving timing diagram according to the second embodiment [Figure 7] Block diagram per unit pixel according to a modification of the second embodiment [Figure 8] Block diagram of a unit pixel according to the third embodiment [Figure 9] Block diagram of a unit pixel according to the fourth embodiment [Figure 10] Pixel driving timing diagram according to the fourth embodiment [Figure 11] FIG. 10 is a timing diagram showing an exposure pattern according to the fifth embodiment. [Figure 12] Timing diagram showing exposure patterns according to the sixth embodiment [Figure 13] Block diagram of a photoelectric conversion system according to embodiment 7. [Figure 14] Block diagram of a photoelectric conversion system according to embodiment 8. [Figure 15] Block diagram of a photoelectric conversion system according to embodiment 9. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiments shown below are intended to embody the technical concept of the present invention and are not intended to limit the present invention. The size and positional relationship of components shown in each drawing may be exaggerated for clarity. In the following description, the same components may be designated by the same reference numerals and their description may be omitted.

[0010] (Embodiment 1) A first embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 is a block diagram of a photoelectric conversion device 100 according to this embodiment. The photoelectric conversion device 100 includes a pixel unit 101, a control pulse generation unit 115, a horizontal scanning circuit unit 111, a readout circuit 112, signal lines 113, and a vertical scanning circuit unit 110. The pixel unit 101 includes a plurality of pixels 104 arranged in a two-dimensional array (matrix). Each pixel 104 includes a photoelectric conversion unit 102 including an avalanche photodiode (hereinafter, referred to as an APD) and a pixel circuit 103. It is sufficient that at least the APDs are arranged in a two-dimensional array in the pixel unit 101. The photoelectric conversion unit 102 converts light into an electrical signal. The pixel circuit 103 outputs the electrical signal converted by the photoelectric conversion unit 102 to a signal line 113.

[0011] The vertical scanning circuit unit 110 receives a control pulse supplied from the control pulse generating unit 115 and supplies the control pulse to each pixel. The vertical scanning circuit unit 110 uses logic circuits such as a shift register and an address decoder.

[0012] The signal output from the photoelectric conversion unit 102 of each pixel is processed by the pixel circuit 103. The pixel circuit 103 is provided with a counter circuit and / or a memory. The following describes a case where the pixel circuit 103 has a memory. A digital value is held in the memory.

[0013] The horizontal scanning circuit unit 111 inputs a control pulse to the pixel circuit 103 to sequentially select each column in order to read out the signal from the memory of each pixel in which the digital signal is held.

[0014] To the signal line 113, a signal is output from the pixel circuit 103 of the pixel 104 selected by the vertical scanning circuit unit 110 for the selected row.

[0015] The signal output to the signal line 113 is output via an output circuit 114 to a recording unit or a signal processing unit outside the photoelectric conversion device 100 .

[0016] 1, pixels 104 are arranged in a two-dimensional array in a pixel section 101. A plurality of pixels 104 may be arranged one-dimensionally in the pixel section 101. Alternatively, only a single pixel may be arranged in the pixel section 101, rather than an array.

[0017] The function of the pixel circuit 103 does not necessarily have to be provided for every pixel 104. For example, a single pixel circuit 103 may be shared by multiple pixels 104, and signal processing may be performed sequentially. To achieve higher sensitivity and higher functionality, the photoelectric conversion device may use a stacked sensor in which a first substrate having a photoelectric conversion unit and a second substrate having a pixel circuit are stacked and joined together. In this case, the photoelectric conversion unit and the pixel circuit are electrically connected via connection wiring provided for each pixel.

[0018] The principle of the speed-up of distance measurement, which is an effect of the present invention, will be described with reference to FIG.

[0019] FIG. 2(i) is a diagram showing a comparative example and is an explanatory diagram of a time-gated TOF method that performs a linear search for the timing of reflected light. FIG. 2(ii) is an explanatory diagram of a method of performing a binary search for the timing of reflected light according to this embodiment. In FIG. 2(i), the white area in each subframe indicates the exposure period of the pixel 104, and the black area indicates the non-exposure period. In this embodiment, the exposure period refers to, for example, a period during which the photoelectric conversion unit 102 is active and a signal from the photoelectric conversion unit 102 is read out to a counter circuit and / or a register circuit. The non-exposure period refers to a period during which a signal from the photoelectric conversion unit 102 is not read out by the counter circuit and / or the register circuit. In the following description, the exposure period refers to a period during which a reverse bias potential capable of avalanche multiplication is applied to the APD, the gate element is turned on, and the counter circuit and / or the register circuit can read out a signal from the APD. The non-exposure period refers to a period during which the gate element is turned off and a signal from the APD is not read out via the gate element. The non-exposure period is not limited to this. For example, the non-exposure period may be a period during which a potential difference applied to the APD is reduced so as to prevent avalanche multiplication in the APD, and the exposure period may be a period during which a potential difference is applied that causes avalanche multiplication in the APD. Alternatively, the non-exposure period may be a period during which control is performed so that the counter circuit and / or the register circuit is not driven, and the exposure period may be a period during which control is performed so that the counter circuit and / or the register circuit is driven.

[0020] 2(i) and 2(ii), the subframes are arranged starting from the emitted light for ease of explanation, but in actual driving, the light intensity of the first subframe is measured with the first emitted light. After that, the second emitted light is emitted at the same timing as the first emitted light, and the light intensity of the second subframe is measured with the second emitted light. Then, the light intensity of the Nth subframe is measured with the Nth emitted light.

[0021] In the comparative example, light intensity measurements are performed N times while shifting the relative timing of the start and end of the exposure period with respect to the light emission timing of the light source. In other words, the reflected light is measured while gradually shifting the start timing of the exposure period. In this way, when the timing of the exposure period is linearly scanned in steps over a predetermined distance measurement range, the time resolution or distance measurement accuracy of reflected light detection increases in proportion to the number of steps N of the linear scan. However, as the number of steps and the number of subframes increase, distance measurement takes longer.

[0022] In contrast, in this embodiment, the period corresponding to the cycle of the emitted light in the first subframe is time-divided into two or more exposure periods. For example, the period is time-divided into two exposure periods, A and B, and the light intensity in each exposure period is measured independently. The light intensity in exposure periods A and B is compared. In the explanatory diagram, the reflected light is included in exposure period A, so the optical signal amount in exposure period A is greater than the optical signal amount in exposure period B. Based on the comparison results, assuming that the reflected light is included in exposure period A, exposure period A is further divided into two within the length of exposure period A of the first subframe to determine exposure periods A and B of the second subframe. In this way, by repeatedly comparing the light intensity in two or more exposure periods in each subframe and determining the exposure pattern for the next subframe, particularly the exposure timing and period, the estimation of the timing of the reflected light is improved. As a result, while linear search requires N light intensity measurements, binary search reduces the number of light intensity measurements to Log2(N), enabling faster distance measurement.

[0023] Although FIG. 2(i) shows only one light irradiation and one exposure period for each subframe, optical signals obtained by repeating each subframe multiple times may be added together. This improves the accuracy of optical signal measurement. In this case, according to the comparative example, the time resolution of reflected light detection or distance measurement accuracy increases in proportion to the number of linear scanning steps N. Therefore, the effect of speeding up distance measurement by using this embodiment is significant.

[0024] Note that Figure 2(ii) shows an example of a binary search method in which the exposure period is divided into two equal parts. Although the following figures will also use an example of dividing the exposure period into two equal parts, the term "binary search method" is not limited to dividing the exposure period into two equal parts. In this specification, the term "binary search method" also refers to a method that divides the exposure period into three or more equal parts. In other words, the binary search method is a name for a method different from the linear scanning method and is not limited to dividing the exposure period into two equal parts. Furthermore, the lengths of the two exposure periods A and B in one subframe may be different. Furthermore, in the comparison process, signals A' and B' obtained by applying a predetermined arithmetic or correction process to the respective signals may be compared, rather than the signal amounts of the exposure periods A and B themselves.

[0025] 3 is an example of a block diagram per unit pixel in this embodiment. As described above, a pixel has a photoelectric conversion unit and a pixel circuit. In FIG. 3, an APD 301 is used as the photoelectric conversion unit. The pixel circuit also has a quench element 302, a gate element 303 (switch), a light quantity value holding unit 31, a comparison circuit (comparison unit) 312, a register circuit 313, and a pulse generation circuit 314. The light quantity value holding unit 31 has a counter circuit 310 and a register circuit 311.

[0026] The APD 301 is connected to a quench element 302 that controls the avalanche current. The photon detection signal output from the APD 301 is temporally controlled by a gate signal GATE input to a gate element 303. The output of the gate element 303 is input to a light intensity value holding unit 31, which is composed of a counter circuit 310 and a register circuit 311. The photon signal passing through the gate element 303 is counted by the counter circuit 310, and the count value is written to the register circuit 311 in response to a trigger signal RTRG. In other words, the register circuit 311 functions as a recording circuit. In response to an enable signal COEN, a comparison circuit 312 compares the output values of the counter circuit 310 and the register circuit 311 and records the comparison result in a register circuit 313. In response to the hold signal of the register circuit 313, a clock signal CLK, and an enable signal PGEN, a pulse generation circuit 314 generates a gate signal GATE that defines the exposure pattern. The reset signals RES1, RES2, and RES3 initialize the signals held in the counter circuit 310, register circuit 311, and register circuit 313, respectively.

[0027] The APD 301 generates charge pairs in response to incident light through photoelectric conversion. A potential based on a potential VH that is higher than the potential VL supplied to the anode is supplied to the cathode of the APD 301. A potential is then supplied to the anode and cathode of the APD 301 so that a reverse bias is applied that causes avalanche multiplication of photons incident on the APD 301. By performing photoelectric conversion while this reverse bias potential is supplied, the charges generated by the incident light undergo avalanche multiplication, generating an avalanche current.

[0028] When a reverse bias potential is supplied and the potential difference between the anode and cathode is greater than the breakdown voltage, the APD operates in Geiger mode. Hereinafter, an APD that uses Geiger mode operation to quickly detect weak signals at the single-photon level is also referred to as a SPAD (Single Photon Avalanche Diode). In this embodiment, it is preferable to use a SPAD for quickly detecting weak signals, but the APD may also operate in linear mode, where signals are multiplied at a voltage equal to or lower than the breakdown voltage.

[0029] The quench element 302 may be a quench element consisting of multiple transistors or a resistor element, instead of a single transistor. When the photocurrent is multiplied by avalanche multiplication in the APD 301, a current resulting from the multiplied charge flows through the connection node between the APD 301 and the quench element 302. The voltage drop caused by this current reduces the potential of the cathode of the APD 301, and the APD 301 no longer forms an avalanche. This stops the avalanche multiplication of the APD 301. The power supply potential VH is then supplied to the cathode of the APD 301 via the quench element 302, and the potential supplied to the cathode of the APD 301 returns to the potential VH. In other words, the operating region of the APD 301 returns to Geiger mode operation. In this way, the quench element 302 functions as a load circuit (quench element) during charge multiplication by avalanche multiplication and suppresses avalanche multiplication (quench operation). Furthermore, the quench element has the function of restoring the operating region of the APD to the Geiger mode after suppressing the avalanche multiplication (recharge operation).

[0030] The gate element 303 may be a switch circuit or logic circuit using multiple transistors instead of a single transistor. In FIG. 3, the exposure period of the pixel is adjusted by controlling the on / off of the gate element 303. The exposure period refers to a period during which the APD 301 is capable of detecting photons and the potential of the APD 301 is input to the light intensity value storage unit 31. The non-exposure period of the pixel refers to a period during which the potential of the APD 301 is not input to the light intensity value storage unit 31. Specifically, the exposure period is a period during which the gate element 303 is on, and the non-exposure period is a period during which the gate element 303 is off. In FIG. 3, the gate element 303 is configured as a PMOS transistor. Therefore, when the signal input to the gate transitions from a first level (high level) to a second level (low level), the gate element 303 turns on, and when the signal transitions from the second level to the first level, the gate element 303 turns off. Note that if the gate element 303 is an NMOS transistor, the opposite occurs. That is, when the signal input to the gate transitions from the second level to the first level, the gate element 303 turns on, and when the signal transitions from the first level to the second level, the gate element 303 turns off. The gate element being in the on state refers to a state in which the APD 301 and the light intensity value storage unit 31 are electrically connected, and the gate element being in the off state refers to a state in which the APD 301 and the light intensity value storage unit 31 are not electrically connected. Note that instead of providing a specific element between the APD 301 and the counter circuit 310, the gate element 303 may be substituted by an operation that temporally switches the enabled / disabled state of the counter operation. In this case, the state in which the counter operation is enabled corresponds to the exposure period, and the state in which the counter operation is disabled corresponds to the non-exposure period.

[0031] The counter circuit 310 may be either a digital counter or an analog counter. The counter circuit 310 is connected to a register circuit 311 and a comparison circuit 312 so that an output signal from the counter is input to the register circuit 311 and the comparison circuit 312. The register circuit 311 can hold the signal output from the counter circuit 310. The register circuit 311 is connected so that its output is input to the comparison circuit 312.

[0032] The light quantity value holding unit 31, the comparison circuit 312, the register circuit 313, and the pulse generation circuit 314 may be partially shared by a plurality of pixels.

[0033] The comparator circuit 312 is connected to compare the signal value output from the counter circuit 310 with the signal value output from the register circuit 311 and input the comparison result to the register circuit 313. The register circuit 313 is also connected to a pulse generator circuit 314. The pulse generator circuit 314 is connected to a gate element, and the on / off of the gate element is controlled based on the output signal from the pulse generator circuit 314. In this embodiment, the exposure period is set by controlling the on / off of the gate element. In other words, the pulse generator circuit 314 functions as a control unit that controls the exposure period.

[0034] The register circuit 313 is connected so that a signal is output to the signal line 113. Distance measurement can be performed based on the signal value output from the register circuit 313. Therefore, the signal line 113 is configured with a number of lines that can output a signal with at least the number of output bits from the register circuit 313.

[0035] In FIG. 3 , in addition to the register circuit 313, the counter circuit 310 and the register circuit 311 are connected to the signal line 113. In this way, by outputting the outputs from the counter circuit 310 and the register circuit 311 to an outside pixel via the signal line 113, the reliability of the distance measurement results can be improved. For example, the signal value output from the register circuit 311 and the signal value output from the counter circuit 310 are output for each frame. The output signal values are then compared. For pixels receiving reflected light, there is a large difference between the signal value output from the register circuit 311 and the signal value output from the counter circuit 310. On the other hand, for pixels not receiving reflected light, only signals based on noise and external light are detected, so there is little difference between the signal value output from the register circuit 311 and the signal value output from the counter circuit 310. By using the absolute value and difference of these signal values, it is possible to obtain information on whether a pixel receives reflected light and data on detected noise and external light. This information can be used to confirm the accuracy of distance measurement, thereby improving the reliability of the distance measurement results.

[0036] When the output values of the register circuit 313, the counter circuit 310, and the register circuit 311 are output to the signal line 113, the number of lines may be such that signals from each circuit can be output individually, or the signal line 113 may be shared by each circuit. When the signal line 113 is shared, the output timing of the signals from each circuit may be shifted, thereby making it possible to detect the signals output from each circuit outside the pixel.

[0037] 4 is a timing diagram showing the operation of the pixel of the photoelectric conversion device according to this embodiment. During the period from time t1 to t2, RES1, RES2, and RES3 are set to high level to initialize the hold signals (Count, Reg1, Reg2) of the counter circuit 310, register circuit 311, and register circuit 313.

[0038] First, we will explain the operation of the first period in the first subframe of the kth frame, which corresponds to the period from time t2 to t7. At time t3, pulsed light is irradiated from the light source toward the measurement object. This pulsed light is reflected by the measurement object and reaches the light-receiving surface of the photoelectric conversion device at time t4. By setting the gate signal GATE input to the gate element to low level during the period from time t3 to t5, the amount of light received by the APD 301 during the first exposure period A is measured. That is, the first exposure period A is initiated by setting the gate signal GATE to low level at the same timing as the light source emits light. In this embodiment, the gate element is configured using a PMOS transistor, so the gate element is ON when low level and OFF when high level. Meanwhile, during the period from time t5 to t6, the gate signal GATE input to the gate element is set to high level, establishing a non-exposure state in which the light signal is not measured. That is, the first exposure period A is the period in which exposure begins after a first delay time has elapsed from the light source emits light. The first exposure period A is terminated by setting the gate signal GATE to high level after a predetermined period has elapsed. At t4 included in the exposure period A, a pulse of reflected light is detected, and the count value Count of the counter circuit 310 increases. By repeating the driving from time t2 to t6 multiple times within the first period of the first subframe, the optical signal of the exposure period A is accumulated.

[0039] Next, a description will be given of the driving for recording the signal held by the counter circuit 310 in the register circuit 311 during the period from time t7 to t12. During the period from time t7 to t12, the enable signal PGEN of the pulse generation circuit 314 is set to low level, preventing the counter circuit 310 from counting the light detection signal from the APD 301. During the period from time t7 to t12, the gate signal GATE input to the gate element is set to high level. During the period from time t8 to t9, the trigger signal RTRG is set to high level, and the output of the counter circuit 310 is recorded in the register circuit 311. This changes the signal value Reg1 held in the register circuit 311. During the period from time t10 to t11, the reset signal RES1 is set to high level, initializing the signal held in the counter circuit 310.

[0040] Next, we will explain the driving of the second period of the first subframe of the kth frame, which corresponds to the period from time t12 to t16. Compared to the driving of the first period of the first subframe described above, the timing at which the gate signal GATE is set to high level is different. In the second period of the first subframe, the period from time t14 to t15 is defined as exposure period B, and the period from time t12 to t14 is defined as non-exposure period. In other words, exposure period B is a period in which exposure begins after a second delay time from the timing of light emission from the light source. The length of the second delay time is different from the length of the first delay time. Exposure period B is ended by setting the gate signal GATE to high level a predetermined period after the start of exposure period B. Unlike the driving of the first period of the first subframe described above, reflected light reaches the light-receiving surface at time t13. At this time, the photoelectric conversion device is in a non-exposure period, so no optical signal is counted.

[0041] Next, we will explain the driving that compares the magnitude of the optical signal amounts during exposure periods A and B during the period from time t16 to t21. As described above, during the period from time t16 to t21, the enable signal PGEN of the pulse generation circuit 314 is set to low level, so that the counter circuit 310 does not count the light detection signal from the APD 301. During the period from time t17 to t18, the enable signal COEN of the comparison circuit 312 is set to high level. Then, the comparison result between the output of the register circuit 311, which holds the signal amount corresponding to exposure period A, and the output of the counter circuit 310, which holds the signal amount corresponding to exposure period B, is recorded as a digital signal in the register circuit 313. This changes the hold signal Reg2 of the register circuit 313. During the period from time t19 to t20, RES1 and RES2 are set to high level, so that the hold signals of the counter circuit 310 and the register circuit 311 are initialized.

[0042] Based on the comparison result, the first period in the second subframe of the kth frame, which corresponds to the period from time t21 to t24, has half the length of the exposure period A in the first subframe. The pulse generation circuit 314 generates a gate signal GATE to set a new exposure period A defined by the period from time t21 to t22. Here, one of the two exposure periods obtained by dividing the exposure period A, in which the signal integration amount in the first subframe was large, is set as the new exposure period A. The remaining exposure period of the exposure period A in the first subframe and the exposure period B in the first subframe are set as non-exposure periods. Similarly, after the recording operation, driving for the second period in the second subframe of the kth frame continues from time t25 onwards. Specifically, of the two exposure periods obtained by dividing the exposure period A, in which the signal integration amount in the first subframe was large, the remaining period of the newly set exposure period A is set as the new exposure period B.

[0043] In this way, the sequence of exposure operation (A), recording operation, exposure operation (B), and comparison operation is repeated a predetermined number of times, and the timing of the reflected light pulse is binary searched, thereby improving the accuracy of measuring the distance to the object to be measured.

[0044] In this embodiment, the frequency of the clock signal CLK input to the pulse generating circuit 314 is doubled at time t21 when the first subframe switches to the second subframe. However, the present invention is not limited to this, and a pulse generating circuit 314 that can switch the interval between exposure patterns for each subframe without changing the frequency may be used. Furthermore, in this embodiment, periodic pulse emission is assumed as the operation of the light source, but the intensity, width, or temporal emission pattern of the emitted light may be switched between different subframes.

[0045] In the above description, the signal value is output from the register circuit 313 after the operation sequence is repeated a predetermined number of times, but this is not limiting. For example, the signal value may be output from the register circuit 313 to the signal line 113 every subframe or every few subframes. This makes it possible to obtain a rough distance measurement result before one frame period ends.

[0046] According to this embodiment, it is possible to measure distances at higher speeds than in the comparative embodiment.

[0047] (Embodiment 2) The second embodiment will be described with reference to FIGS. 5 and 6. FIG. 5 is an example of a block diagram of a unit pixel in this embodiment. This embodiment differs from the first embodiment in the following points. In this embodiment, the light intensity value storage unit 31 is composed of two counter circuits 310a and 310b. The output terminal of the APD 301 is connected to two parallel gate elements 303a and 303b, and the outputs of these two gate elements are input in parallel to the counter circuits 310a and 310b, respectively. A comparison circuit 312 compares the outputs of the counter circuits 310a and 310b. A pulse generation circuit 314 generates independent gate signals GATE1 and GATE2 for the gate elements 303a and 303b. The following describes the differences from the first embodiment, and omits a description of the points that are substantially the same as those in the first embodiment.

[0048] The output from gate element 303a is input to counter circuit 310a. The output from gate element 303b is input to counter circuit 310b. Counter circuits 310a and 310b are connected so that their outputs are input to comparison circuit 312. Note that in this specification, components with similar configurations may have Roman letters such as a, b, or c suffixed to their reference numerals and their explanations may be omitted.

[0049] FIG. 6 is a timing diagram showing the pixel drive operation of the photoelectric conversion device according to this embodiment. Reset signals RES1, RES2, and RES3 initialize the signals held in the counter circuit 310a, counter circuit 310b, and register circuit 313, respectively. Unlike the first embodiment, which repeats a sequence of exposure operation (A), recording operation, exposure operation (B), and comparison operation, this embodiment differs in that it repeats a sequence of exposure operations (A, B) and comparison operation. Within the first subframe of the kth frame, which corresponds to the period from time t3 to t6, an exposure period A defined by setting the gate signal GATE1 to a high level and an exposure period B defined by setting the gate signal GATE2 to a high level are set complementarily. In this embodiment, the gate elements 303a and 303b are configured with inverter circuits and logic circuits. When avalanche multiplication occurs in the APDs 301a and 301b, the cathode potential drops. When the inverter circuit included in the gate element 303a exceeds a threshold, the potential is inverted. When this signal is input to an AND circuit, which is a logic circuit, a high-level signal is output from gate elements 303a and 303b. For example, the period from time t3 to t4 is defined as exposure period A, and the optical signals during this period are counted by counter circuit 310a, while the period from time t4 to t5 is defined as exposure period B, and the optical signals during this period are counted by counter circuit 310b.

[0050] As in the first embodiment, the output signals of counter circuits 310a and 310b are compared during the period from time t6 to t7. Based on the results of this comparison, new exposure periods A and B are set for the second sub-frame of the kth frame, which corresponds to the period from time t7 to t10. Here, exposure period A, which had a large signal integration amount in the first sub-frame, is divided into two equal exposure periods, which are set as new exposure periods A and B. Then, as in the first sub-frame, the amount of light during the newly set exposure period A is counted by counter circuit 310a, and the amount of light during exposure period B is counted by counter circuit 310b.

[0051] According to this embodiment, similar to the first embodiment, it is possible to perform distance measurement at a higher speed than the comparative embodiment. Moreover, since the intensities of the optical signals in the exposure periods A and B can be acquired in parallel within a single subframe, the period from the exposure operation to the comparison operation can be shortened compared to the first embodiment, and the distance to the measurement object can be measured at a higher speed. Furthermore, even if the measurement object is moving, the time lag between the optical signal measurements in the exposure periods A and B can be reduced, and the accuracy of the distance measurement can be improved.

[0052] (Modification of the second embodiment) A modification of the second embodiment will be described with reference to FIG. 7. FIG. 7 is an example of a block diagram per unit pixel in the modification. The modification differs from the second embodiment in that the outputs from two independent APDs 301a and 301b are connected to two gate elements 303a and 303b. Other than the points described below, the modification is substantially the same as the second embodiment, and therefore description thereof will be omitted. The driving method corresponding to this modification conforms to the driving method of the second embodiment.

[0053] 7, the output from APD 301a is input to gate element 303a, and the output from APD 301b is input to gate element 303b. Therefore, counter circuit 310a counts the amount of light detected by APD 301a, and counter circuit 310b counts the amount of light detected by APD 301b.

[0054] According to this modification, as with the second embodiment, distance measurement can be performed at a higher speed than the comparative embodiment. Furthermore, by using two spatially adjacent APDs, the intensities of optical signals during exposure periods A and B can be acquired in parallel within a single subframe, thereby shortening the time from the exposure operation to the comparison operation and speeding up measurement of the distance to the object. Furthermore, even when the object is moving, the time lag between the optical signal measurements during exposure periods A and B can be minimized, improving the accuracy of distance measurement.

[0055] (Embodiment 3) Embodiment 3 will be described with reference to FIG. 8. FIG. 8 is an example of a block diagram per unit pixel in this embodiment. This embodiment differs in that outputs from two independent APDs 301a and 301b and two waveform shaping circuits 820a and 820b connected thereto are input to a simultaneous detection circuit 821, and the output of the simultaneous detection circuit 821 is connected to two gate elements 303a and 303b. Other matters are substantially the same as those in the modified embodiment of embodiment 2 except as described below, and therefore description thereof will be omitted.

[0056] The waveform shaping circuits 820a and 820b have the function of shaping the waveforms of the outputs from the respective APDs, and may be, for example, inverter circuits, buffer circuits, or monostable circuits that shorten the width of the pulse waveform. The simultaneous detection circuit 821 outputs a pulse signal when a predetermined number or more of signals from the multiple waveform shaping circuits become high level simultaneously or at close timing. It should be noted that three or more APDs and waveform shaping circuits may be connected to one simultaneous detection circuit 821. In this embodiment, the same driving method as in embodiment 2 is used.

[0057] According to this embodiment, similar to the first embodiment, it is possible to perform distance measurement at a higher speed than the comparative embodiment. Furthermore, it is possible to selectively detect only photons that are close in time and space due to reflected light, and to filter out randomly detected external light components and dark output. Therefore, it is possible to reduce the influence of external light and dark output on the distance measurement accuracy of the ToF method.

[0058] (Embodiment 4) The fourth embodiment will be described with reference to FIGS. 9 and 10. FIG. 9 is an example of a block diagram per unit pixel in this embodiment. This embodiment differs from the first embodiment in that a charge-storage photodiode 901 is used instead of the APD 301, and an analog signal is input to the comparison circuit 312. Other than the points described below, this embodiment is substantially the same as the first embodiment, and therefore further description will be omitted.

[0059] The photocharge accumulated in the photodiode 901 is discharged or input to the light-amount holding unit 91 when a control signal OFD is input to the overflow drain circuit 902. The light-amount holding unit 91 consists of transfer gates 903a and 903b, holding units 910a and 910b, and transfer gates 905a and 905b. The photocharge photoelectrically converted by the photodiode 901 receives a gate signal GATE1 or GATE2 and is transferred to the holding unit 910a or 910b via the transfer gate 903a or 903b. The signal held in the holding unit is transferred to two floating diffusion (FD) regions FD1 and FD2 when the transfer gates 905a and 905b receive gate signals TX1 and TX2. The potentials VFD1 and VFD2 of the two FD regions are initialized when the reset circuits 907a and 907b receive reset signals RES1 and RES2, respectively. A comparator circuit 312 receives an enable signal COEN, compares the magnitudes of potentials VFD1 and VFD2, and records the comparison result in a register circuit 313. A pulse generator circuit 314 receives the signal held in the register circuit 313, a clock signal CLK, and an enable signal PGEN, and generates gate signals GATE1 and GATE2 that define the exposure pattern, and a control signal OFD. A reset signal RES3 initializes the signal held in the register circuit 313.

[0060] 10 is a timing diagram showing the operation of a pixel of the photoelectric conversion device according to this embodiment. During the period from time t1 to t2, RES1, RES2, and RES3 are set to high level to initialize the potentials VFD1 and VFD2 of the two FD regions and the signal held in the register circuit 313. During the period from time t2 to t3, the control signal OFD is set to high level to reset the charge accumulated in the photodiode 901.

[0061] First, we will explain the driving in the first subframe of the kth frame, which corresponds to the period from time t3 to t8. At time t3, a pulse of light is irradiated from the light source toward the object to be measured. This pulse of light is reflected by the object to be measured and reaches the light-receiving surface at time t4. By setting the gate signal GATE1 to a high level from time t4 to t5, the photoelectric charge received by the photodiode 901 during the first exposure period A, which corresponds to times t3 to t5, is transferred. Furthermore, by setting the gate signal GATE2 to a high level from time t6 to t7, the photoelectric charge received by the photodiode 901 during the second exposure period B, which corresponds to times t5 to t7, is transferred. At this time, a pulse of reflected light is detected at t4, which is included in the exposure period A, and the voltage value VM1 of the holding unit 910a changes. By repeating the driving from time t3 to t7 multiple times within the first subframe, the optical signals during exposure periods A and B are accumulated.

[0062] Next, we will explain the driving that compares the signals held in the holding units 910a and 910b during the period from time t8 to t16. During the period from time t8 to t16, the enable signal PGEN of the pulse generation circuit 314 is set to low level, preventing the light detection signal from the photodiode 901 from being transferred to the holding units 910a and 910b. During the period from time t9 to t10, RES1 and RES2 are set to high level, resetting the FD potentials VFD1 and VFD2. During the period from time t10 to t11, the transfer signals TX1 and TX2 are set to high level, transferring the signal charges held in the holding units 910a and 910b to FD1 and FD2, respectively. During the period from time t12 to t13, the enable signal COEN of the comparison circuit 312 is set to high level. The comparison result between VFD1, which corresponds to the integrated signal amount during exposure period A, and VFD2, which corresponds to the integrated signal amount during exposure period B, is recorded as a digital signal in the register circuit 313. During the period from time t14 to t15, RES1 and RES2 are set to high level, and the FD potentials VFD1 and VFD2 are reset again. During the period from time t15 to t16, the control signal OFD is set to high level, and the charge accumulated in the photodiode 901 is reset.

[0063] In the second subframe of the kth frame, which corresponds to the period from time t16 to t20, a new exposure period A, a new exposure period B, and a non-exposure period are set based on the comparison results, and the pulse generation circuit 314 generates gate signals GATE1 and GATE2 and a control signal OFD. The new exposure period A is half the length of the exposure period A in the first subframe and is defined by the period from time t16 to t17. The new exposure period B is defined by the period from time t17 to t18. The non-exposure period is defined by the period from time t18 to t19. Here, the exposure period A, which had a large signal integration amount in the first subframe, is divided into two equal exposure periods, which are set as new exposure periods A and B. As described above, after the comparison operation from time t20 to t21, driving of the third subframe of the kth frame continues from time t21 onwards.

[0064] In this way, the sequence of exposure operations (A, B) and comparison operations is repeated multiple times, and the timing of the reflected light pulse is subjected to a binary search, thereby improving the accuracy of distance measurement to the object to be measured.

[0065] In this embodiment, the "charge holding method" has been described as an example in which a capacitor for holding a photocharge signal is used as the means for holding the optical signal. However, a "voltage holding method" may also be used in which charge information is converted into voltage information via a transistor amplifier or the like and this voltage signal is held.

[0066] According to this embodiment, similar to the first embodiment, it is possible to measure distances at a higher speed than the comparative embodiment. Furthermore, by using a charge-storage photodiode instead of an APD, it is possible to reduce the operating voltage. Furthermore, by using a capacitance element that stores charge or voltage instead of a counter circuit or a register circuit, it is possible to achieve miniaturization of pixels.

[0067] (Embodiment 5) This embodiment will be described with reference to Fig. 11. Fig. 11 is an explanatory diagram of an example of a procedure for selecting an exposure pattern in this embodiment. Fig. 11(i) shows a case where reflected light reaches the photoelectric conversion device in the first half of the period corresponding to the light emission cycle, and Fig. 11(ii) shows a case where reflected light reaches the sensor in the second half of the period corresponding to the light emission cycle.

[0068] This embodiment differs from the first embodiment in that the exposure periods A and B of the first subframe do not cover the entire period corresponding to the light emission cycle. In the first subframe of FIG. 11(i), the optical signal levels of the exposure periods A and B are compared. If neither of the signals in the two exposure periods reaches a certain threshold, the signal comparison determines that "no signal is included in either exposure period A or B." The exposure periods A and B in the second subframe are set so as not to overlap with the exposure periods A and B of the first subframe and to be the same length as the exposure periods A and B of the first subframe. In the second subframe, the timing of the reflected light is included in exposure period B, resulting in a signal level exceeding the threshold. Therefore, the signal comparison determines that "a signal is included in exposure period B," and the exposure periods A and B of the third subframe are determined by further dividing the exposure period B of the second subframe in half.

[0069] On the other hand, in Figure 11(ii), the timing of the reflected light is included in exposure period A of the first subframe, so when the signals are compared it is determined that "the signal is included in exposure period A." Then, exposure period A of the first subframe is further divided in half to determine exposure periods A and B of the second subframe.

[0070] By using the binary search method of this embodiment, the distance measurement can be speeded up by searching preferentially the period around the timing of the reflected light estimated in advance.

[0071] (Embodiment 6) This embodiment will be described with reference to Fig. 12. Fig. 12 is an explanatory diagram of an example of distance measurement using binary search in this embodiment. Fig. 12(i) differs from embodiment 1 in that the pulse width of the emitted light is set to be approximately the same as the exposure periods A and B of the fourth subframe, which is the final subframe.

[0072] Figure 12(ii) is an enlarged view of the reflected light and exposure pattern of the fourth subframe around the period from time t1 to t2 in Figure 12(i). Consider the case where the reflected light arrives with a delay of Δt from the start time t1 of exposure pattern A. Since most of the reflected light is contained within exposure period A, a comparison of the signal amounts shows that exposure period A is larger than exposure period B. In this case, if the pulse width of the reflected light and the widths of exposure periods A and B are equivalent, Δt can be calculated using the internal division ratio of signal amounts A and B using the following formula: Δt=T / 2×B / (A+B) Equation 1 In the above equation (1), it is assumed that the effects of external light and dark output can be ignored. However, external light and dark output may be measured separately and subtracted from signals A and B, and then Δt may be calculated using the above equation.

[0073] According to this embodiment, it is possible to achieve a time resolution finer than the length of the exposure period of the final sub-frame, thereby improving the accuracy of distance measurement.

[0074] (Embodiment 7) FIG. 13 is a block diagram showing the configuration of a photoelectric conversion system 1200 according to this embodiment. The photoelectric conversion system 1200 of this embodiment includes a photoelectric conversion device 1204. Here, any of the photoelectric conversion devices described in the above embodiments can be applied to the photoelectric conversion device 1204. The photoelectric conversion system 1200 can be used, for example, as an imaging system. Specific examples of imaging systems include a digital still camera, a digital camcorder, and a surveillance camera. FIG. 13 shows an example of a digital still camera as the photoelectric conversion system 1200.

[0075] 13 includes a photoelectric conversion device 1204, a lens 1202 that forms an optical image of a subject on the photoelectric conversion device 1204, an aperture 1203 that adjusts the amount of light that passes through the lens 1202, and a barrier 1201 that protects the lens 1202. The lens 1202 and the aperture 1203 form an optical system that focuses light on the photoelectric conversion device 1204.

[0076] The photoelectric conversion system 1200 includes a signal processing unit 1205 that processes an output signal output from a photoelectric conversion device 1204. The signal processing unit 1205 performs signal processing operations, performing various corrections and compression on an input signal as necessary and outputting the signal. The photoelectric conversion system 1200 also includes a buffer memory unit 1206 for temporarily storing image data and an external interface unit (external I / F unit) 1209 for communicating with an external computer or the like. The photoelectric conversion system 1200 also includes a recording medium 1211 such as a semiconductor memory for recording or reading image data, and a recording medium control interface unit (recording medium control I / F unit) 1210 for recording or reading data from the recording medium 1211. The recording medium 1211 may be built into the photoelectric conversion system 1200 or may be removable. Communication between the recording medium control I / F unit 1210 and the recording medium 1211 and communication from the external I / F unit 1209 may be performed wirelessly.

[0077] The photoelectric conversion system 1200 further includes an overall control and calculation unit 1208 that performs various calculations and controls the entire digital still camera, and a timing generation unit 1207 that outputs various timing signals to the photoelectric conversion device 1204 and the signal processing unit 1205. Here, timing signals and the like may be input from an external source, and the photoelectric conversion system 1200 only needs to include at least the photoelectric conversion device 1204 and the signal processing unit 1205 that processes the output signal output from the photoelectric conversion device 1204. As explained in the fourth embodiment, the timing generation unit 1207 may be mounted on the photoelectric conversion device. The overall control and calculation unit 1208 and the timing generation unit 1207 may be configured to perform some or all of the control functions of the photoelectric conversion device 1204.

[0078] The photoelectric conversion device 1204 outputs an image signal to the signal processing unit 1205. The signal processing unit 1205 performs predetermined signal processing on the image signal output from the photoelectric conversion device 1204 and outputs image data. The signal processing unit 1205 generates an image using the image signal. The signal processing unit 1205 may also perform distance measurement calculations on the signal output from the photoelectric conversion device 1204. The signal processing unit 1205 and the timing generating unit 1207 may be mounted on the photoelectric conversion device. That is, the signal processing unit 1205 and the timing generating unit 1207 may be provided on the substrate on which the pixels are arranged, or may be provided on a separate substrate. By configuring an imaging system using the photoelectric conversion device of each of the above-described embodiments, an imaging system capable of acquiring higher quality images can be realized.

[0079] (Embodiment 8) FIG. 14 is a block diagram showing an example of the configuration of a distance image sensor (ToF system) that is an electronic device that uses the photoelectric conversion device described in the above-described embodiment.

[0080] 14, the range image sensor 401 is configured to include an optical system 402, a photoelectric conversion device 403, an image processing circuit 404, a monitor 405, and a memory 406. The range image sensor 401 can obtain a range image according to the distance to the subject by receiving light (modulated light or pulsed light) that is projected toward the subject from a light source device 411 and reflected from the surface of the subject.

[0081] The optical system 402 is configured to have one or more lenses, and guides image light (incident light) from a subject to the photoelectric conversion device 403 , forming an image on the light receiving surface (sensor section) of the photoelectric conversion device 403 .

[0082] The photoelectric conversion device 403 is one of the photoelectric conversion devices according to the above-described embodiments, and a distance signal indicating a distance determined from a light reception signal output from the photoelectric conversion device 403 is supplied to the image processing circuit 404 .

[0083] The image processing circuit 404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 403. The distance image (image data) obtained by this image processing is then supplied to a monitor 405 for display, or supplied to a memory 406 for storage (recording).

[0084] In the range image sensor 401 configured in this way, by applying the above-described photoelectric conversion device, it is possible to obtain, for example, a more accurate range image as the pixel characteristics improve.

[0085] (Embodiment 9) The photoelectric conversion system and the moving body of this embodiment will be described with reference to Fig. 15. Fig. 15 is a schematic diagram showing an example of the configuration of the photoelectric conversion system and the moving body according to this embodiment. In this embodiment, an example of an in-vehicle camera is shown as the photoelectric conversion system.

[0086] FIG. 15 shows an example of a vehicle system and a photoelectric conversion system mounted thereon for capturing images. In this embodiment, two photoelectric conversion devices 1302 are arranged in front of the vehicle 1300. Specifically, if the center line of the vehicle 1300's heading or outer shape (e.g., vehicle width) is regarded as an axis of symmetry, and the two photoelectric conversion devices 1302 are arranged symmetrically about the axis of symmetry, this is preferable for obtaining distance information between the vehicle 1300 and an object to be photographed and determining the possibility of a collision. Furthermore, it is preferable that the photoelectric conversion devices 1302 are arranged so as not to obstruct the driver's field of vision when the driver visually checks the situation outside the vehicle 1300 from the driver's seat. Note that a photoelectric conversion device 1302 may also be arranged at the rear of the vehicle 1300, and a configuration may be adopted in which an alarm is sounded when a vehicle approaching from behind is approached.

[0087] In this way, the photoelectric conversion device can be applied to automatic driving control that follows other vehicles, automatic driving control that prevents the vehicle from straying from its lane, etc. Furthermore, the photoelectric conversion system 1301 can be applied not only to vehicles such as the vehicle itself, but also to moving bodies (moving devices) such as ships, aircraft, and industrial robots. In addition, the photoelectric conversion system 1301 can be applied not only to moving bodies, but also to a wide range of devices that use object recognition, such as intelligent transport systems (ITS).

[0088] The photoelectric conversion device of the present invention may further be configured to be capable of acquiring various types of information such as distance information.

[0089] (Other embodiments) Although the embodiments have been described above, the present invention is not limited to these embodiments and various changes and modifications are possible. In addition, the embodiments are mutually applicable. [Explanation of symbols]

[0090] 104 pixel section 301 Avalanche Photodiode 302 Quench Circuit 303 Gate element 31 Light intensity value storage unit 312 Comparison Section

Claims

1. an avalanche photodiode; a light quantity value holding unit having a counter circuit that counts the signal avalanche-multiplied by the avalanche photodiode, and that holds a light quantity value based on signal charges generated during a first exposure period and a second exposure period that is different from the first exposure period; a comparison unit that compares a light amount value based on the signal charges generated in the first exposure period with a light amount value based on the signal charges generated in the second exposure period; a control unit that controls, based on a comparison result of the comparison unit, to set a third exposure period and a fourth exposure period that is different from the third exposure period in at least one of a start timing and an end timing within a length range of the period determined to have a large light amount value out of the first exposure period and the second exposure period; the third exposure period and the fourth exposure period are shorter than at least one of the first exposure period and the second exposure period; the first exposure period and the second exposure period are periods obtained by time-dividing a predetermined period, A photoelectric conversion device characterized in that the third exposure period and the fourth exposure period are time-divided periods of the first exposure period and the second exposure period in which the light quantity value is determined to be large.

2. 2. The photoelectric conversion device according to claim 1, wherein the light quantity value storage unit includes a recording circuit that stores the count value of the counter circuit.

3. the counter circuit includes a first counter circuit and a second counter circuit; the light amount value during the first exposure period is counted by the first counter circuit; 3. The photoelectric conversion device according to claim 1, wherein the light amount value during the second exposure period is counted by the second counter circuit.

4. the avalanche photodiodes include a first avalanche photodiode and a second avalanche photodiode; the counter circuit includes a first counter circuit and a second counter circuit; during the first exposure period, the light amount value obtained from the first avalanche photodiode is counted by the first counter circuit; 4. The photoelectric conversion device according to claim 1, wherein the light amount value obtained from the second avalanche photodiode during the second exposure period is counted by the second counter circuit.

5. 5. The photoelectric conversion device according to claim 1, wherein the avalanche photodiode is a SPAD that operates in a Geiger mode.

6. the first exposure period and the second exposure period are the same length; 6. The photoelectric conversion device according to claim 1, wherein the third exposure period and the fourth exposure period have the same length.

7. a switch is disposed between a node of the avalanche photodiode and a node of the light amount value storage unit, the switch controlling whether or not the node of the avalanche photodiode and the light amount value storage unit is connected; 7. The photoelectric conversion device according to claim 1, wherein the first exposure period, the second exposure period, the third exposure period, and the fourth exposure period are set by controlling the on / off of the switch.

8. the first exposure period is started by transitioning the control signal of the switch from a first level to a second level at the same timing as the light emission timing of the light source or at a timing when a predetermined period has elapsed, and the first exposure period is ended by transitioning the control signal of the switch from the second level to the first level after a predetermined period has elapsed since the start of the first exposure period; The photoelectric conversion device according to claim 7, characterized in that the second exposure period is started by transitioning the control signal of the switch from the first level to the second level after a predetermined period has elapsed since the end of the first exposure period, and the second exposure period is ended by transitioning the control signal of the switch from the second level to the first level after a predetermined period has elapsed since the start of the second exposure period.

9. 9. The photoelectric conversion device according to claim 7, wherein the switch is formed of a PMOS transistor.

10. repeating the first exposure period a plurality of times, and then repeating the second exposure period a plurality of times; the light quantity value obtained in the first exposure period is a value obtained by integrating the light quantity values obtained in the plurality of first exposure periods, 10. The photoelectric conversion device according to claim 1, wherein the light quantity value obtained during the second exposure period is a value obtained by accumulating the light quantity values obtained during the multiple second exposure periods.

11. A signal processing unit is provided, 11. The photoelectric conversion device according to claim 10, wherein the light quantity value obtained in the first exposure period and the light quantity value obtained in the second exposure period are output to the signal processing unit.

12. outputting the light quantity values of the first exposure periods before the integration to the signal processing unit; 12. The photoelectric conversion device according to claim 11, wherein the light quantity values of the plurality of second exposure periods before being integrated are also output to the signal processing unit.

13. the avalanche photodiode is disposed on a first substrate; the comparison unit is disposed on a second substrate, 13. The photoelectric conversion device according to claim 1, wherein the first substrate and the second substrate are laminated and bonded together.

14. The photoelectric conversion device is a photoelectric conversion device that measures light emitted from a light source and reflected by an object, the first exposure period is a period in which exposure starts after a first delay time has elapsed from the timing of light emission from the light source, the second exposure period is a period in which exposure starts after a second delay time has elapsed from the timing of light emission from the light source, The first delay time and the second delay time have different lengths.

14. The photoelectric conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

15. A light source and The photoelectric conversion device according to any one of claims 1 to 14, A photoelectric conversion system that detects light irradiated from the light source and reflected from an object by the photoelectric conversion device.

Images