Photoelectric conversion device

Abstract

To provide a photoelectric conversion device that can improve the accuracy of signal acquisition.SOLUTION: A photoelectric conversion device has a photodiode for performing avalanche multiplication, a recharge circuit for performing a recharge operation for setting the photodiode after the avalanche multiplication is performed to a state in which the avalanche multiplication can be performed again on the basis of a first control signal including periodic pulses, and a counter for counting the number of times the avalanche multiplication occurs by being enabled on the basis of a second control signal. The recharge circuit performs the recharge operation before the counter is enabled on the basis of the second control signal.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a photon-counting type photoelectric conversion device. This photoelectric conversion device digitally counts the number of photons incident on a light-receiving section that performs avalanche multiplication, and outputs the count value as a digital signal. More specifically, the photoelectric conversion device of Patent Document 1 includes a photodiode that performs avalanche multiplication, a generation circuit that generates a control signal, and a control circuit that controls a recharge operation to return the photodiode to a state where avalanche multiplication is possible after avalanche multiplication. Such a photoelectric conversion device can output a digital signal corresponding to the frequency of photon reception. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-123847 Summary of the Invention [Problem to be solved by the invention]

[0004] In a photoelectric conversion device capable of performing a recharge operation as in Patent Document 1, the state of the photodiode before the recharge operation may affect the photon count value.

[0005] An object of the present invention is to provide a photoelectric conversion device that can further improve the accuracy of signal acquisition. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a photodiode that performs avalanche multiplication; a recharge circuit that performs a recharge operation to return the photodiode after the avalanche multiplication to a state in which the avalanche multiplication can be performed again, based on a first control signal including a pulse that periodically repeats a transition from a first level to a second level; and a counter that is enabled based on a second control signal and counts the number of times the avalanche multiplication has occurred, In one photon counting period, A photoelectric conversion device is provided, characterized in that the first control signal transitions from the first level to the second level and from the second level to the first level before the counter is enabled based on the second control signal. According to another aspect of the present invention, there is provided a photoelectric conversion device comprising: a photodiode that performs avalanche multiplication; a recharge circuit that performs a recharge operation to return the photodiode after avalanche multiplication to a state in which the avalanche multiplication can be performed again based on a first control signal including a pulse that periodically repeats transitions from a first level to a second level; and a counter that is enabled based on a second control signal and counts the number of times the avalanche multiplication has occurred, wherein during a first period in which the counter is disabled by the second control signal, the first control signal maintains the first level; during a second period following the first period in which the counter is disabled by the second control signal, the first control signal transitions from the first level to the second level and from the second level to the first level; and during a third period following the second period, the counter is enabled by the second control signal, and the length of the first period is longer than the length of the second period. [Effects of the Invention]

[0007] According to the present invention, a photoelectric conversion device capable of further improving the accuracy of signal acquisition is provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a schematic configuration of a photoelectric conversion device according to a first embodiment. [Figure 2] 1 is a circuit diagram showing a schematic configuration of a pixel according to a first embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of the configuration of a pixel according to the first embodiment. [Figure 4] FIG. 3 is a timing chart showing the operation of the pixel according to the first embodiment. [Figure 5] FIG. 10 is a diagram illustrating an example of the configuration of a pixel according to a second embodiment. [Figure 6] FIG. 10 is a timing chart showing the operation of the pixel according to the second embodiment. [Figure 7] FIG. 10 is a diagram illustrating an example of the configuration of a pixel according to a third embodiment. [Figure 8] FIG. 10 is a timing chart showing the operation of a pixel according to the third embodiment. [Figure 9] FIG. 10 is a timing chart showing the operation of a pixel according to the fourth embodiment. [Figure 10] FIG. 10 is a block diagram of a light detection system according to a fifth embodiment. [Figure 11] FIG. 10 is a block diagram of a light detection system according to a sixth embodiment. [Figure 12] FIG. 13 is a schematic diagram of an endoscopic surgery system according to a seventh embodiment. [Figure 13] FIG. 13 is a schematic diagram of a light detection system according to an eighth embodiment. [Figure 14] FIG. 13 is a schematic diagram of a moving body according to an eighth embodiment. [Figure 15] 13 is a flowchart showing the operation of the light detection system according to the eighth embodiment. [Figure 16] FIG. 13 is a diagram showing a specific example of an electronic device according to the ninth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or corresponding elements in multiple drawings are designated by common reference numerals, and their description may be omitted or simplified.

[0010] [First embodiment] A photoelectric conversion device and a driving method thereof according to this embodiment will be described with reference to Figures 1 to 4. The photoelectric conversion device may be, for example, a solid-state imaging device, a focus detection device, a distance measurement device, a TOF (Time-Of-Flight) camera, etc.

[0011] 1 is a block diagram showing a schematic configuration of a photoelectric conversion device 1 according to this embodiment. As shown in FIG. 1, the photoelectric conversion device 1 includes a pixel array 10, a vertical selection circuit 12, a signal processing circuit 14, a horizontal selection circuit 13, an output circuit 16, and a control circuit 17.

[0012] The pixel array 10 has a plurality of pixels 11 arranged in a matrix across a plurality of rows and a plurality of columns. In Fig. 1, the plurality of pixels 11 arranged from the first row to the mth row and the first column to the nth column are shown with reference numerals indicating the row number and the column number. For example, the pixel 11 arranged in the second row and the first column is assigned the reference numeral "P21."

[0013] The number of rows and columns of the pixel array 10 is not particularly limited. Furthermore, the pixels 11 do not necessarily have to be arranged two-dimensionally in the pixel array 10. For example, the pixel array 10 may be composed of a single pixel 11, or the pixels 11 may be arranged one-dimensionally in the row direction or column direction in the pixel array 10.

[0014] A control line PVSEL is arranged in each row of the pixel array 10, extending in a first direction (the horizontal direction in FIG. 1). The control line PVSEL is connected to each of the pixels 11 arranged in the first direction, and serves as a signal line common to these pixels 11. In FIG. 1, the control line PVSEL is shown with a reference symbol indicating the row number. For example, the control line in the first row is labeled "PVSEL[1]."

[0015] The control line PVSEL of each row is connected to a vertical selection circuit 12. The vertical selection circuit 12 is a circuit section that supplies control signals for driving signal generation circuits in the pixels 11 to the pixels 11 via the control line PVSEL.

[0016] A signal line 15 is arranged in each column of the pixel array 10, extending in a second direction (the vertical direction in FIG. 1) intersecting the first direction. The signal line 15 is connected to each of the pixels 11 aligned in the second direction, and serves as a common signal line for these pixels 11.

[0017] The signal lines 15 are connected to a signal processing circuit 14. The signal processing circuit 14 has signal processing blocks arranged corresponding to each column of the pixel array 10, and each signal processing block is connected to the signal line 15 of the corresponding column. The signal processing circuit 14 has a function of holding signals output from the pixels 11 via the signal line 15 of the corresponding column.

[0018] The horizontal selection circuit 13 is a circuit section that supplies the signal processing circuit 14 with a control signal for reading out a signal from the signal processing circuit 14. The horizontal selection circuit 13 supplies a control signal to the signal processing block of each column of the signal processing circuit 14 via a control line PHSEL. The signal processing block that receives the control signal from the horizontal selection circuit 13 outputs the signal held in the holding unit to the output circuit 16. In FIG. 1, the control line PHSEL is shown together with a symbol indicating the column number. For example, the control line for the first column is assigned the symbol "PHSEL[1]".

[0019] The output circuit 16 is a circuit section for outputting the supplied signal to the outside of the photoelectric conversion device 1. The control circuit 17 is a circuit section for supplying control signals that control the operations and timings of the vertical selection circuit 12, the signal processing circuit 14, the horizontal selection circuit 13, and the output circuit 16. At least some of the control signals that control the operations and timings of the vertical selection circuit 12, the signal processing circuit 14, the horizontal selection circuit 13, and the output circuit 16 may be supplied from the outside of the photoelectric conversion device 1.

[0020] 2 is a circuit diagram showing a schematic configuration of a pixel 11 according to this embodiment. In FIG. 2, one pixel 11 and multiple functional blocks in a vertical selection circuit 12 that supplies control signals to the pixel 11 are extracted and shown.

[0021] The pixel 11 includes a photodiode 111, a recharge circuit 112, a pixel signal processing circuit 113, a NOT circuit 114, and an AND circuit 115. The vertical selection circuit 12 includes a counter enable circuit 121, a clock generation circuit 122, and a recharge enable circuit 123. The recharge circuit 112 includes a PMOS transistor M1.

[0022] The photodiode 111 is a photoelectric conversion unit that generates charge pairs in response to incident light through photoelectric conversion. The photodiode 111 is also configured to operate as an avalanche photodiode that performs avalanche multiplication. A voltage VL is supplied to the anode of the photodiode 111. The cathode of the photodiode 111 is connected to the drain of the PMOS transistor M1 and the pixel signal processing circuit 113. A voltage VH is supplied to the source of the PMOS transistor M1. The voltage VL is, for example, approximately −20 V, and the voltage VH is, for example, approximately 3.3 V.

[0023] The counter enable circuit 121 is connected to the pixel signal processing circuit 113. The counter enable circuit 121 outputs a control signal to the pixel signal processing circuit 113 to control the period during which the counter in the pixel signal processing circuit 113 is enabled. The pixel signal processing circuit 113 counts the number of avalanche multiplication events and outputs a digital signal corresponding to the count value to the outside. The clock generation circuit 122 is connected to a first input terminal of an AND circuit 115 (first logic circuit), and the recharge enable circuit 123 is connected to a second input terminal of the AND circuit 115. The clock generation circuit 122 outputs a clock pulse including a periodic pulse as a control signal. The recharge enable circuit 123 outputs a control signal that controls the enablement of the recharge operation in the recharge circuit 112. The output terminal of the AND circuit 115 is connected to an input terminal of the NOT circuit 114. The output terminal of the NOT circuit 114 is connected to the gate of the PMOS transistor M1.

[0024] When the PMOS transistor M1 is turned on based on the logical AND of the output signal of the clock generation circuit 122 and the output signal of the recharge enable circuit 123, a reverse bias voltage of voltages VH and VL is applied to the photodiode 111. When incident light generates charges in the photodiode 111 to which the reverse bias voltage is applied, these charges undergo avalanche multiplication, generating an avalanche current. This reverse bias voltage is set to a voltage higher than the breakdown voltage of the photodiode 111, and the photodiode 111 operates as a Geiger-mode avalanche photodiode.

[0025] FIG. 3 is a diagram showing an example of the configuration of the pixel 11 according to this embodiment. FIG. 3 shows in more detail the configuration of the pixel signal processing circuit 113 shown in FIG. 2. The pixel signal processing circuit 113 has a counter 113a and a NOR circuit 113b. The counter enable circuit 121, the clock generation circuit 122, and the recharge enable circuit 123 output a control signal P_CNTEN_B (second control signal), a control signal PCLK (first control signal), and a control signal P_PDEN_V (third control signal), respectively. The control signal PCLK and the control signal P_PDEN_V are input to an AND circuit 115, and the output signal of the AND circuit 115 is input to a NOT circuit 114. The AND circuit 115 and the NOT circuit 114 output a signal obtained by inverting the logical product of these signals to control the PMOS transistor M1 of the recharge circuit 112. Also, as shown in FIG. 3, the connection node between the cathode of the photodiode 111 and the drain of the PMOS transistor M1 is referred to as nodeA. The signal output from node A, that is, the signal output from the photodiode 111, is defined as a signal Vc.

[0026] The counter enable circuit 121 is connected to a first input terminal of a NOR circuit 113b (second logic circuit), and nodeA is connected to a second input terminal of the NOR circuit 113b. The output terminal of the NOR circuit 113b is connected to the counter 113a. That is, the NOR circuit 113b outputs a signal Vpulse, which is an inverted logical sum of the signal Vc and the control signal P_CNTEN_B, to the counter 113a. The signal Vpulse is a signal having a pulse waveform.

[0027] The counter 113a counts the number of times the signal Vpulse output from the NOR circuit 113b transitions from low to high, thereby generating a count signal having a count value corresponding to the incidence of photons on the photodiode 111.

[0028] 4 is a timing diagram showing the operation of the pixel 11 according to this embodiment. "P_CNTEN_B," "PCLK," "P_PDEN_V," "Vc," and "Vpulse" shown in FIG. 4 indicate the potentials of the signals shown in FIG. 3. In "Photon Incidence" in FIG. 4, arrows indicate the timing at which photons are incident on the photodiode 111. In "Count Value" in FIG. 4, the count value held in the counter 113a at the corresponding time is shown.

[0029] During the period before time t1, the control signal P_CNTEN_B is at a high level, and the control signal PCLK, the control signal P_PDEN_V, the signal Vc, and the signal Vpulse are at a low level. The count value is p. During this period, the control signal P_PDEN_V is at a low level, so the output of the AND circuit 115 is at a low level. The output of the NOT circuit 114, i.e., the potential at the gate of the PMOS transistor M1, is at a high level. Therefore, the PMOS transistor M1 is off, and node A between the recharge circuit 112 and the photodiode 111 is in a floating state. Thus, during the period when the control signal P_PDEN_V is at a low level, the recharge operation of the photodiode 111 is disabled.

[0030] During this period, the control signal P_CNTEN_B is at a high level, so the output of the NOR circuit 113b, i.e., the signal Vpulse, is at a low level regardless of the level of the signal Vc, and therefore the counting in the counter 113a is disabled.

[0031] At time t1, the control signal PCLK and the control signal P_PDEN_V change from low to high. As a result, the output of the AND circuit 115 changes to high, and the output of the NOT circuit 114 changes to low. At this time, the PMOS transistor M1 turns on, and the photodiode 111 is recharged. This recharge changes the signal Vc to high, and the photodiode 111 enters a standby state where avalanche multiplication is possible. Thus, the period during which the control signal P_PDEN_V is high is the period during which the recharge operation of the photodiode 111 is enabled. Photons incident on the photodiode 111 during the period during which the recharge operation is enabled can be counted. Therefore, time t1 is the start time of the photon counting period T1.

[0032] At time t2, the control signal P_CNTEN_B goes low. The period during which the control signal P_CNTEN_B is low is the period during which the counting operation of the counter 113a is enabled. Therefore, time t2 is the start time of the count valid period T2.

[0033] At time t3, the control signal PCLK changes from low to high. As a result, the potential of the control signal PCLK exceeds the logic threshold of the AND circuit 115, and the output of the AND circuit 115 becomes high. Then, the output of the NOT circuit 114 becomes low, and the PMOS transistor M1 turns on. However, since the signal Vc has been high since before time t3, the level of the signal Vc does not change.

[0034] At time t4, a photon is incident on the photodiode 111. This causes avalanche multiplication in the photodiode 111, causing the signal Vc to transition from high to low. The potential of the signal Vc then becomes lower than the logic threshold of the NOR circuit 113b, causing the signal Vpulse to transition from low to high. This change in the potential of the signal Vpulse increases the count value of the count signal output from the counter 113a by 1 LSB (Least Significant Bit). In other words, the count value changes from p to p+1.

[0035] At time t5, the control signal PCLK changes from low to high. As a result, the potential of the control signal PCLK exceeds the logical threshold of the AND circuit 115, and the output of the AND circuit 115 changes to high. Then, the output of the NOT circuit 114 changes to low, and the PMOS transistor M1 turns on. At this time, the photodiode 111 is recharged. That is, the signal Vc changes from low to high, and the photodiode 111 enters a standby state where avalanche multiplication is possible. Furthermore, in conjunction with the transition of the signal Vc from low to high, the signal Vpulse output from the NOR circuit 113b also changes from high to low.

[0036] At time t6, a photon is incident on the photodiode 111. This causes avalanche multiplication in the photodiode 111, causing the signal Vc to transition from high to low. The potential of the signal Vc then becomes lower than the logic threshold of the NOR circuit 113b, causing the signal Vpulse to transition from low to high. This change in the potential of the signal Vpulse increases the count value of the count signal output from the counter 113a by 1 LSB. That is, the count value changes from p+1 to p+2.

[0037] At time t7, a photon is incident on the photodiode 111. However, at time t7, the signal Vc is at a low level and the signal Vpulse output from the NOR circuit 113b remains at a high level, so the count value does not increase.

[0038] At time t8, the control signal PCLK changes from low to high. As a result, the potential of the control signal PCLK exceeds the logical threshold of the AND circuit 115, and the output of the AND circuit 115 changes to high. Then, the output of the NOT circuit 114 changes to low, and the PMOS transistor M1 turns on. At this time, the photodiode 111 is recharged, the signal Vc changes from low to high, and the photodiode 111 enters a standby state in which avalanche multiplication is possible. In conjunction with the transition of the signal Vc from low to high, the signal Vpulse output from the NOR circuit 113b also changes from high to low.

[0039] At time t9, the control signal P_CNTEN_B goes to high level, and the control signal P_PDEN_V goes to low level. Furthermore, after time t9, the level of the control signal PCLK is maintained at low level. When the control signal P_CNTEN_B goes to high level, the counting operation by the counter 113a is deactivated. Therefore, time t9 is the end time of the count valid period T2. Furthermore, when the control signal P_PDEN_V goes to low level, the recharge operation of the photodiode 111 is deactivated. Therefore, time t9 is the end time of the photon counting period T1.

[0040] At time t10, a photon is incident on the photodiode 111. This causes avalanche multiplication in the photodiode 111, causing the signal Vc to transition from high to low. The potential of the signal Vc then becomes lower than the logic threshold of the NOR circuit 113b. However, because the control signal P_CNTEN_B is high and the signal Vpulse output from the NOR circuit 113b does not change, the count value does not increase.

[0041] As described above, in this embodiment, the photon counting period T1, in which the recharge operation of the photodiode 111 is enabled, starts at time t1, which is before time t2, in which the counting valid period T2, in which the counter 113a is enabled, starts. The effect of applying such a driving method will be described.

[0042] In a driving method in which the count valid period T2 can start before the start of the photon count period T1, counting may start before the recharge operation. If counting starts before the recharge operation, the state of the photodiode 111 before the recharge operation may affect the count value. For example, if the photodiode 111 has already undergone avalanche multiplication (i.e., the signal Vc is at a low level) at the start of the count valid period T2, the count value will be incremented by one at the start of the count valid period T2. In this case, the count value will be one more than the number of photons that actually entered, which may result in an error in the count value.

[0043] Even if the photon count period T1 and the effective count period T2 are designed to start simultaneously, in an actual product, they may not start simultaneously due to errors in the timing of the control signals, etc. In such cases, errors in the count value may occur due to the factors described above. Factors that can cause errors in the timing of the control signals as described above include, for example, a large number of pixels 11 arranged in the pixel array 10, variations in the characteristics of the elements in the pixels 11, and differences in the positions of the pixels 11 within the pixel array.

[0044] In contrast, the photoelectric conversion device 1 of this embodiment is configured so that the photon count period T1, which enables the recharge operation, starts at time t1, before time t2, when the count valid period T2 starts. This reduces errors in the count number caused by counting before the recharge operation. Therefore, this embodiment provides a photoelectric conversion device 1 that can further improve the accuracy of signal acquisition.

[0045] 3, the control signal PCLK and the control signal P_PDEN_V are processed by the AND circuit 115 and the NOT circuit 114 arranged in the pixel 11 to generate the signal to be supplied to the recharge circuit 112, but this is not limiting. For example, similar processing may be performed in the vertical selection circuit 12.

[0046] Furthermore, although FIG. 4 shows an example in which the potential of the control signal PCLK does not fluctuate outside the photon count period T1, the control signal PCLK may alternate between high and low levels outside the photon count period T1 in the same way as during the photon count period T1.

[0047] [Second embodiment] The photoelectric conversion device and its driving method according to this embodiment will be described with reference to Figures 5 and 6. Descriptions of configurations common to the first embodiment may be omitted or simplified.

[0048] FIG. 5 is a diagram showing an example of the configuration of a pixel 11 according to this embodiment. FIG. 5 differs from FIG. 3 in that an OR circuit 116 (third logic circuit) is further provided. The counter enable circuit 121 is connected to a first input terminal of the OR circuit 116, and the clock generation circuit 122 is connected to a second input terminal of the OR circuit 116. The output terminal of the OR circuit 116 is connected to a first input terminal of the NOR circuit 113b. That is, the control signal P_CNTEN_B and the control signal PCLK are input to the OR circuit 116, and the OR circuit 116 outputs the logical sum of these signals (fourth control signal) to the NOR circuit 113b. As a result, in this embodiment, when the control signal PCLK is high, the signal Vpulse is low regardless of the potential of the signal Vc.

[0049] 6 is a timing diagram showing the operation of the pixel 11 according to this embodiment. The operation from time t1 to time t3 and the operation from time t6 to time t10 are the same as those in FIG. 4, and therefore their explanation will be omitted. The difference between FIG. 6 and FIG. 4 is that a plurality of photons are continuously incident on the photodiode 111 from time t21 to time t24.

[0050] At time t21, a photon is incident on the photodiode 111. This causes avalanche multiplication in the photodiode 111, causing the signal Vc to transition from high to low. The potential of the signal Vc then becomes lower than the logic threshold of the NOR circuit 113b, causing the signal Vpulse to transition from low to high. This change in the potential of the signal Vpulse increases the count value of the count signal output from the counter 113a by 1 LSB. That is, the count value changes from p to p+1.

[0051] At time t22, the control signal PCLK changes from low to high. This turns on the PMOS transistor M1. However, between time t21 and time t24, multiple photons are continuously incident on the photodiode 111, so avalanche multiplication continues to occur in the photodiode 111. As a result, the recharge operation is not performed sufficiently, and the signal Vc does not rise from low to high, so it remains low. In this way, the signal Vc input to the second input terminal of the NOR circuit 113b remains low. However, because the output signal of the OR circuit 116 is high and a high-level signal is input to the first input terminal of the NOR circuit 113b, the signal Vpulse transitions from high to low at time t22.

[0052] At time t23, the control signal PCLK changes from high to low. At this time, the output signal of the OR circuit 116 changes from high to low and becomes lower than the logic threshold of the NOR circuit 113b. This causes the signal Vpulse to change from low to high. This change in the potential of the signal Vpulse increases the count value of the count signal output from the counter 113a by 1 LSB. That is, the count value changes from p+1 to p+2.

[0053] At time t24, a photon is incident on the photodiode 111. However, at time t24, the signal Vc is at a low level, and the signal Vpulse that is the output of the NOR circuit 113b remains at a high level and does not change, so the count value does not increase.

[0054] At time t25, the control signal PCLK changes from low to high. As a result, the potential of the control signal PCLK exceeds the logical threshold of the AND circuit 115, and the output of the AND circuit 115 changes to high. Then, the output of the NOT circuit 114 changes to low, and the PMOS transistor M1 turns on. At this time, the photodiode 111 is recharged, the signal Vc changes from low to high, and the photodiode 111 enters a standby state where avalanche multiplication is possible. The subsequent operation is the same as in FIG. 4, so a description thereof will be omitted.

[0055] According to this embodiment, similarly to the first embodiment, a photoelectric conversion device 1 is provided that can further improve the accuracy of signal acquisition. Furthermore, in this embodiment, when photons are continuously incident on the photodiode 111, as from time t21 to time t24, avalanche multiplication continues to occur, and even when the recharge operation is not performed sufficiently, some of the photons can be counted. Therefore, the accuracy of signal acquisition can be further improved.

[0056] [Third embodiment] The photoelectric conversion device and its driving method according to this embodiment will be described with reference to Figures 7 and 8. Descriptions of configurations common to the first and second embodiments may be omitted or simplified.

[0057] 7 is a diagram showing an example of the configuration of a pixel 11 according to this embodiment. FIG. 7 differs from FIG. 5 in that the NOT circuit 114 is replaced with a NOR circuit 117 (fourth logic circuit) and that a reset circuit 124 is provided in the vertical selection circuit 12. A first input terminal of the NOR circuit 117 is connected to the output terminal of the AND circuit 115. The reset circuit 124 is connected to a second input terminal of the NOR circuit 117 and the counter 113a. An output terminal of the NOR circuit 117 is connected to the gate of the PMOS transistor M1. The reset circuit 124 outputs a control signal P_RES (fifth control signal). When a high-level control signal P_RES is input to the counter 113a, the count value held in the counter 113a is reset to zero, which is its initial value.

[0058] 8 is a timing diagram showing the operation of the pixel 11 according to this embodiment. The operation from time t2 onwards is the same as in FIG. 6, and therefore a description thereof will be omitted. The difference between FIG. 8 and FIG. 6 is that the counter 113a is reset at time t0, which is before time t1.

[0059] During the period before time t0, the control signal P_CNTEN_B is at a high level, the control signal PCLK, the control signal P_PDEN_V, the control signal P_RES, the signal Vc, and the signal Vpulse are at a low level, and the count value is q.

[0060] At time t0, the control signal P_RES goes high. This causes the output of the NOR circuit 117 to go low, turning on the PMOS transistor M1. At this time, the photodiode 111 is recharged, the signal Vc goes from low to high, and the photodiode 111 goes into a standby state where avalanche multiplication is possible. Also, the counter 113a is reset, and the count value changes from q to zero.

[0061] At time t1, the control signal PCLK and the control signal P_PDEN_V change from low to high. This turns on the PMOS transistor M1. However, since the signal Vc has been high before time t1, the level of the signal Vc does not change. The subsequent operation is the same as in FIG. 6, so a description thereof will be omitted.

[0062] According to this embodiment, similarly to the first and second embodiments, a photoelectric conversion device 1 capable of further improving the accuracy of signal acquisition is provided. Furthermore, in this embodiment, the photodiode 111 can be recharged even when the counter 113a is reset.

[0063] 8, the timing at which the control signals PCLK and P_PDEN_V change from low to high at time t1 is the start time of the photon counting period T1. However, the start time of the photon counting period T1 is not limited to this. The final recharge operation before time t2 at which the control signal P_CNTEN_B changes from high to low may be performed by the control signal P_RES changing from low to high. In that case, the start time of the photon counting period T1 may be the timing at which the control signal P_RES changes from low to high.

[0064] Furthermore, the timing at which the control signals PCLK and P_PDEN_V change from low level to high level may be the same as the timing at which the control signal P_RES changes from low level to high level.

[0065] [Fourth embodiment] Based on the configuration of the third embodiment, a more preferred example of the period of the control signal PCLK, the timing of the recharge operation, the timing of enabling the counter 113a, etc. will be described as a fourth embodiment with reference to Fig. 9. The configuration, operation timing, etc. of the pixel 11 are the same as those of the third embodiment, so description thereof will be omitted.

[0066] FIG. 9 is a timing diagram showing the operation of the pixel 11 according to this embodiment. The operation at each time is the same as that in FIG. 8, but FIG. 9 also shows a period T3 from time t1 to time t3 and a period T4 from time t1 to time t2. The period T3 corresponds to the pulse period of the control signal PCLK. The period T4 occurs before the start of the count valid period and corresponds to the period from the last time the PMOS transistor M1 is turned on to the start of the count valid period T2. The operation at each time is the same as that in FIG. 8, so a description thereof will be omitted.

[0067] As shown in Figure 9, the length of period T4 is preferably equal to or shorter than period T3, i.e., equal to or shorter than the pulse period of the control signal PCLK. If period T4 is made longer than period T3, the number of control signals PCLK in count valid period T2 will decrease, which may result in photon count omissions. Therefore, by making period T4 equal to or shorter than period T3, the number of control signals PCLK in count valid period T2 can be maintained, thereby reducing photon count omissions.

[0068] According to this embodiment, similarly to the first to third embodiments, a photoelectric conversion device 1 capable of further improving the accuracy of signal acquisition is provided. Furthermore, in this embodiment, it is possible to reduce photon count omissions.

[0069] 9 shows an example in which the recharge operation immediately before the count valid period T2 is performed when the control signal PCLK goes high. However, as described in the description of FIG. 8, the recharge operation immediately before the count valid period T2 may be performed when the control signal P_RES goes high.

[0070] [Fifth embodiment] A light detection system according to a fifth embodiment of the present invention will be described with reference to Fig. 10. Fig. 10 is a block diagram of the light detection system according to this embodiment. The light detection system according to this embodiment is an imaging system that acquires an image based on incident light.

[0071] The photoelectric conversion device in the above-described embodiment can be applied to various imaging systems. Examples of imaging systems include digital still cameras, digital camcorders, camera heads, copiers, fax machines, mobile phones, vehicle-mounted cameras, observation satellites, and surveillance cameras. Fig. 10 shows a block diagram of a digital still camera as an example of an imaging system.

[0072] The imaging system 7 shown in Fig. 10 includes a barrier 706, a lens 702, an aperture 704, an imaging device 70, a signal processing unit 708, a timing generating unit 720, an overall control and calculation unit 718, a memory unit 710, a recording medium control I / F unit 716, a recording medium 714, and an external I / F unit 712. The barrier 706 protects the lens, and the lens 702 forms an optical image of a subject on the imaging device 70. The aperture 704 varies the amount of light that passes through the lens 702. The imaging device 70 is configured like the photoelectric conversion device of the above-mentioned embodiment, and converts the optical image formed by the lens 702 into image data. The signal processing unit 708 performs various processes, such as correction and data compression, on the imaging data output from the imaging device 70.

[0073] The timing generating unit 720 outputs various timing signals to the imaging device 70 and the signal processing unit 708. The overall control / calculation unit 718 controls the entire digital still camera, and the memory unit 710 temporarily stores image data. The recording medium control I / F unit 716 is an interface for recording or reading image data to or from the recording medium 714, and the recording medium 714 is a removable recording medium such as a semiconductor memory for recording or reading image data. The external I / F unit 712 is an interface for communicating with an external computer or the like. Timing signals and the like may be input from outside the imaging system 7, and the imaging system 7 only needs to have at least the imaging device 70 and the signal processing unit 708 for processing image signals output from the imaging device 70.

[0074] In this embodiment, the imaging device 70 and the signal processing unit 708 may be formed on the same semiconductor substrate, or the imaging device 70 and the signal processing unit 708 may be formed on separate semiconductor substrates.

[0075] Furthermore, each pixel of the image capture device 70 may include a first photoelectric conversion unit and a second photoelectric conversion unit. The signal processing unit 708 processes a pixel signal based on the charge generated in the first photoelectric conversion unit and a pixel signal based on the charge generated in the second photoelectric conversion unit, and can acquire information about the distance from the image capture device 70 to the subject.

[0076] [Sixth embodiment] Fig. 11 is a block diagram of a light detection system according to this embodiment, more specifically, a range image sensor using the photoelectric conversion device described in the above embodiment.

[0077] 11, the range image sensor 401 includes 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 receives light (modulated light, pulsed light) emitted from a light source device 411 toward a subject and reflected by the surface of the subject. The range image sensor 401 can acquire a range image according to the distance to the subject, based on the time between light emission and light reception.

[0078] The optical system 402 includes one or more lenses, guides image light (incident light) from a subject to the photoelectric conversion device 403 , and forms an image on the light receiving surface (sensor section) of the photoelectric conversion device 403 .

[0079] The photoelectric conversion devices of the above-described embodiments can be applied as the photoelectric conversion device 403. The photoelectric conversion device 403 supplies the image processing circuit 404 with a distance signal indicating the distance determined from the light reception signal.

[0080] 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 the image processing can be displayed on a monitor 405 and stored (recorded) in a memory 406.

[0081] The range image sensor 401 configured in this manner can acquire an accurate range image by applying the above-described photoelectric conversion device.

[0082] [Seventh embodiment] The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system, which is an example of an optical detection system.

[0083] Fig. 12 is a schematic diagram of an endoscopic surgery system according to this embodiment. Fig. 12 shows an operator (doctor) 1131 performing surgery on a patient 1132 on a patient bed 1133 using an endoscopic surgery system 1103. As shown in the figure, the endoscopic surgery system 1103 includes an endoscope 1100, a surgical tool 1110, an arm 1121, and a cart 1134 on which various devices for endoscopic surgery are mounted.

[0084] The endoscope 1100 includes a lens barrel 1101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 1132, and a camera head 1102 connected to the base end of the lens barrel 1101. Although Fig. 12 shows the endoscope 1100 configured as a so-called rigid scope having a rigid lens barrel 1101, the endoscope 1100 may also be configured as a so-called flexible scope having a flexible lens barrel.

[0085] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 1101. A light source device 1203 is connected to the endoscope 1100. Light generated by the light source device 1203 is guided to the tip of the lens barrel 1101 by a light guide extending inside the lens barrel 1101, and is irradiated via the objective lens towards an observation target inside the body cavity of the patient 1132. Note that the endoscope 1100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0086] An optical system and a photoelectric conversion device are provided inside the camera head 1102, and light reflected from an observation object (observation light) is focused onto the photoelectric conversion device by the optical system. The observation light is photoelectrically converted by the photoelectric conversion device to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observation image. The photoelectric conversion device may be any of the photoelectric conversion devices described in the above-described embodiments. The image signal is transmitted to a camera control unit (CCU) 1135 as RAW data.

[0087] The CCU 1135 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 1100 and the display device 1136. Furthermore, the CCU 1135 receives an image signal from the camera head 1102 and performs various image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0088] Under the control of the CCU 1135 , the display device 1136 displays an image based on the image signal that has been subjected to image processing by the CCU 1135 .

[0089] The light source device 1203 includes a light source such as an LED (Light Emitting Diode), and supplies the endoscope 1100 with irradiation light when photographing an operation site or the like.

[0090] The input device 1137 is an input interface for the endoscopic surgery system 1103. A user can input various information and instructions to the endoscopic surgery system 1103 via the input device 1137.

[0091] The treatment tool control device 1138 controls the driving of the energy treatment tool 1112 for cauterizing tissue, incising, sealing blood vessels, or the like.

[0092] The light source device 1203 can supply illumination light to the endoscope 1100 when photographing the surgical site, and can be, for example, a white light source such as an LED, a laser light source, or a combination of these. When the white light source is configured by combining RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision. This makes it possible to adjust the white balance of the captured image in the light source device 1203. In this case, laser light from each of the RGB laser light sources can be irradiated onto the observation object in a time-division manner, and the drive of the image sensor of the camera head 1102 can be controlled in synchronization with the irradiation timing. This makes it possible to capture images corresponding to each RGB in a time-division manner. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0093] Furthermore, the driving of the light source device 1203 may be controlled so that the intensity of light output from the light source device 1203 is changed at predetermined time intervals. By controlling the driving of the image sensor of the camera head 1102 in synchronization with the timing of the change in the light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free from so-called blocked-up shadows and blown-out highlights.

[0094] Furthermore, the light source device 1203 may be configured to supply light in a predetermined wavelength band corresponding to special light observation. Special light observation can utilize, for example, the wavelength dependence of light absorption in body tissue. Specifically, by irradiating light with a narrower band than the light (i.e., white light) used in normal observation, a specific tissue, such as blood vessels on the surface of the mucosa, can be photographed with high contrast. Alternatively, special light observation may involve fluorescence observation, in which an image is obtained using fluorescence generated by irradiating excitation light. Fluorescence observation can involve irradiating excitation light onto a body tissue and observing the fluorescence from the body tissue, or locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the body tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 1203 can be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0095] [Eighth embodiment] The light detection system and moving body of this embodiment will be described with reference to Figures 13, 14(a), 14(b), 14(c), and 15. In this embodiment, an example of an in-vehicle camera will be shown as the light detection system.

[0096] FIG. 13 is a schematic diagram of a photodetection system according to this embodiment, illustrating an example of a vehicle system and a photodetection system mounted on the vehicle system. The photodetection 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 any of the photoelectric conversion devices according to the above-described embodiments. 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 may be incorporated into the photoelectric conversion device 1302. The light detection system 1301 is provided with at least two sets of an optical system 1314 , a photoelectric conversion device 1302 and an image pre-processing unit 1315 , and the output from each set of image pre-processing units 1315 is input to the integrated circuit 1303 .

[0097] The integrated circuit 1303 is an integrated circuit for use in an imaging system, and includes an image processing unit 1304 including a storage medium 1305, an optical distance measurement unit 1306, a distance measurement calculation unit 1307, an object recognition unit 1308, and an abnormality detection unit 1309. The image processing unit 1304 performs image processing such as development and defect correction on the output signal of the image pre-processing unit 1315. The storage medium 1305 temporarily stores the captured image and stores the defect positions of the captured pixels. The optical distance measurement unit 1306 focuses or measures the distance to the subject. The distance measurement calculation unit 1307 calculates distance information from multiple image data acquired by multiple photoelectric conversion devices 1302. The object recognition unit 1308 recognizes subjects such as cars, roads, signs, and people. If the abnormality detection unit 1309 detects an abnormality in the photoelectric conversion device 1302, it notifies the main control unit 1313 of the abnormality.

[0098] The integrated circuit 1303 may be realized by dedicated hardware, a software module, or a combination thereof. It may also be realized by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like, or a combination thereof.

[0099] The main control unit 1313 supervises and controls the operations of the light detection system 1301, the vehicle sensor 1310, the control unit 1320, etc. Instead of having the main control unit 1313, the light detection system 1301, the vehicle sensor 1310, and the control unit 1320 may each have a communication interface and send and receive control signals via a communication network according to, for example, the CAN standard.

[0100] The integrated circuit 1303 has a function of receiving a control signal from the main control unit 1313 or transmitting a control signal or a set value to the photoelectric conversion device 1302 by its own control unit.

[0101] The optical detection system 1301 is connected to a vehicle sensor 1310 and can detect the vehicle's driving conditions, such as vehicle speed, yaw rate, and steering angle, as well as the conditions of the environment outside the vehicle and other vehicles and obstacles. The vehicle sensor 1310 also serves as a distance information acquisition unit that acquires distance information to an object. The optical detection system 1301 is also connected to a driving assistance control unit 1311 that performs various driving assistance functions, such as automatic steering, automatic cruising, and collision prevention functions. In particular, the collision determination function determines whether or not a collision with another vehicle or obstacle has occurred based on the detection results of the optical detection system 1301 and the vehicle sensor 1310. This allows for avoidance control when a collision is predicted, and activation of safety devices in the event of a collision.

[0102] The light detection system 1301 is also connected to an alarm device 1312 that issues an alarm to the driver based on the determination result of the collision determination unit. For example, if the collision determination unit determines that there is a high possibility of a collision, the main control unit 1313 performs vehicle control such as applying the brakes, releasing the accelerator, and suppressing engine output, thereby avoiding the collision or mitigating damage. The alarm device 1312 issues an alarm to the user by issuing an alarm such as a sound, displaying alarm information on the display screen of a car navigation system or an instrument panel, applying vibration to the seat belt or steering wheel, etc.

[0103] The light detection system 1301 in this embodiment can capture images of the surroundings of the vehicle, for example, the front or rear. Figures 14(a), 14(b), and 14(c) are schematic diagrams of a moving object in this embodiment, showing a configuration in which the light detection system 1301 captures an image of the area in front of the vehicle.

[0104] The two photoelectric conversion devices 1302 are disposed in front of the vehicle 1300. Specifically, it is preferable that the center line of the vehicle 1300 relative to its forward / backward direction or its outer shape (for example, its width) be regarded as an axis of symmetry, and that the two photoelectric conversion devices 1302 be disposed symmetrically about the axis of symmetry. This makes it possible to effectively obtain distance information between the vehicle 1300 and an object to be photographed and to determine the possibility of a collision. It is also preferable that the photoelectric conversion devices 1302 be disposed in a position that does not obstruct the driver's field of vision when the driver visually checks the situation outside the vehicle 1300 from the driver's seat. It is preferable that the warning device 1312 be disposed in a position that is easily within the driver's field of vision.

[0105] Next, a fault detection operation of the photoelectric conversion device 1302 in the photodetection system 1301 will be described with reference to Fig. 15. Fig. 15 is a flowchart showing the operation of the photodetection system in this embodiment. The fault detection operation of the photoelectric conversion device 1302 can be performed in accordance with steps S1410 to S1480 shown in Fig. 15.

[0106] In step S1410, startup settings are made for the photoelectric conversion device 1302. That is, setting information for the operation of the photoelectric conversion device 1302 is transmitted from outside the photodetection system 1301 (for example, from the main control unit 1313) or from inside the photodetection system 1301, and the photoelectric conversion device 1302 starts imaging operations and fault detection operations.

[0107] Next, in step S1420, the photoelectric conversion device 1302 acquires pixel signals from the valid pixels. Furthermore, in step S1430, the photoelectric conversion device 1302 acquires output values ​​from failure detection pixels provided for failure detection. These failure detection pixels include photoelectric conversion elements, just like the valid pixels. A predetermined voltage is written to these photoelectric conversion elements. The failure detection pixels output signals corresponding to the voltage written to these photoelectric conversion elements. Note that steps S1420 and S1430 may be executed in reverse order.

[0108] Next, in step S1440, the photodetection system 1301 determines whether the expected output value of the fault detection pixel matches the actual output value from the fault detection pixel. If the result of the determination in step S1440 indicates that the expected output value and the actual output value match, the photodetection system 1301 proceeds to processing in step S1450, determines that the imaging operation is being performed normally, and proceeds to processing in step S1460. In step S1460, the photodetection system 1301 transmits the pixel signals of the scanning row to the storage medium 1305 for temporary storage. Thereafter, the photodetection system 1301 returns to processing in step S1420 and continues the fault detection operation. On the other hand, if the result of the determination in step S1440 indicates that the expected output value and the actual output value do not match, the photodetection system 1301 proceeds to processing in step S1470. In step S1470, the light detection system 1301 determines that there is an abnormality in the imaging operation, and issues an alarm 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. Thereafter, in step S1480, the light detection system 1301 stops the photoelectric conversion device 1302, and ends the operation of the light detection system 1301.

[0109] In this embodiment, the flowchart is looped for each line, but the flowchart may be looped for each set of lines, or the fault detection operation may be performed for each frame. The issuance of the alarm in step S1470 may be notified to the outside of the vehicle via a wireless network.

[0110] Furthermore, although the present embodiment has been described as a control for preventing collisions with other vehicles, the present invention is also applicable to control for automatic driving by following other vehicles, control for automatic driving so as not to deviate from a lane, and the like. Furthermore, the light detection system 1301 is not limited to vehicles such as the subject vehicle, but can be applied to moving bodies (moving devices) such as ships, aircraft, and industrial robots. In addition, the present invention is not limited to moving bodies, but can be applied to a wide range of devices that use object recognition, such as intelligent transport systems (ITS).

[0111] 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.

[0112] [Ninth embodiment] FIG. 16(a) is a diagram showing a specific example of an electronic device according to this embodiment, illustrating glasses 1600 (smart glasses). The glasses 1600 are provided with a photoelectric conversion device 1602 according to any of the above-described embodiments. That is, the glasses 1600 are an example of a light detection system to which the photoelectric conversion device 1602 according to any of the above-described embodiments can be applied. A display device including a light-emitting device such as an OLED or LED may be provided on the rear side of the lens 1601. The photoelectric conversion device 1602 may be one or more. Furthermore, multiple types of photoelectric conversion devices may be combined. The arrangement position of the photoelectric conversion device 1602 is not limited to that shown in FIG. 16(a).

[0113] The glasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the photoelectric conversion device 1602 and the display device described above. The control device 1603 also controls the operations of the photoelectric conversion device 1602 and the display device. The lens 1601 is formed with an optical system for focusing light onto the photoelectric conversion device 1602.

[0114] FIG. 16(b) shows glasses 1610 (smart glasses) according to one application example. The glasses 1610 include a control device 1612, which is equipped with a photoelectric conversion device corresponding to the photoelectric conversion device 1602 and a display device. A lens 1611 includes a photoelectric conversion device within the control device 1612 and an optical system for projecting light emitted from the display device, and an image is projected onto the lens 1611. The control device 1612 functions as a power source for supplying power to the photoelectric conversion device and the display device, and controls the operation of the photoelectric conversion device and the display device. The control device 1612 may also include a gaze detection unit for detecting the gaze of the wearer. Infrared light may be used for gaze detection. The infrared light emitter emits infrared light toward the eyeball of a user gazing at a displayed image. An imaging unit having a light receiving element detects the emitted infrared light reflected from the eyeball, thereby obtaining an image of the eyeball. By providing a reduction means for reducing the amount of light from the infrared light emitting section to the display section in a plan view, degradation of image quality is reduced.

[0115] The control device 1612 detects the user's line of sight with respect to the displayed image from the captured image of the eyeball obtained by capturing infrared light. Any known method can be used for gaze detection using the captured image of the eyeball. As an example, a gaze detection method based on the Purkinje image formed by reflection of irradiated light on the cornea can be used.

[0116] More specifically, gaze detection processing is performed based on the pupil-corneal reflex method, which calculates a gaze vector representing the direction (rotation angle) of the eyeball based on the pupil image and Purkinje image included in the captured image of the eyeball, thereby detecting the user's gaze.

[0117] The display device of this embodiment may have a photoelectric conversion device having a light receiving element, and may control the image displayed on the display device based on information on the user's line of sight from the photoelectric conversion device.

[0118] Specifically, the display device determines a first field of view area where the user gazes and a second field of view area other than the first field of view area based on the line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device or by an external control device. In the display area of ​​the display device, the display resolution of the first field of view area may be controlled to be higher than the display resolution of the second field of view area. In other words, the resolution of the second field of view area may be lower than that of the first field of view area.

[0119] The display area may also include a first display area and a second display area different from the first display area. A high-priority area may be determined from the first display area and the second display area based on line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device or by an external control device. The resolution of the high-priority area may be controlled to be higher than the resolution of areas other than the high-priority area. In other words, the resolution of an area with a relatively low priority may be lowered.

[0120] Note that AI (Artificial Intelligence) may be used in determining the first field of view area and the area with high priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to an object in the line of sight from the image of the eyeball, using as training data an image of the eyeball and the direction in which the eyeball in the image was actually looking. The AI ​​program may be provided in either the display device or the photoelectric conversion device, or in an external device. If the external device has the AI ​​program, it may be transmitted to the display device from a server or the like via communication.

[0121] When display control is performed based on visual recognition detection, this embodiment can be preferably applied to smart glasses that further include a photoelectric conversion device that captures an image of the outside world. The smart glasses can display captured external information in real time.

[0122] [Modified embodiment] The present invention is not limited to the above-described embodiments and can be modified in various ways. For example, an example in which part of the configuration of one embodiment is added to another embodiment, or an example in which part of the configuration of another embodiment is replaced with another embodiment, is also an embodiment of the present invention.

[0123] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0124] It should be noted that the above-described embodiments are merely examples of specific embodiments for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited by these embodiments. In other words, the present invention can be carried out in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0125] 1 Photoelectric conversion device 111 Photodiode 112 Recharge Circuit 113a Counter

Claims

1. a photodiode that performs avalanche multiplication; a recharge circuit that performs a recharge operation to return the photodiode after the avalanche multiplication to a state where the avalanche multiplication can be performed again, based on a first control signal including a pulse that periodically repeats a transition from a first level to a second level; a counter that is enabled based on a second control signal to count the number of times the avalanche multiplication occurs; and During one photon counting period, the first control signal transitions from the first level to the second level and from the second level to the first level before the counter is enabled based on the second control signal. A photoelectric conversion device characterized by:

2. A photodiode that performs avalanche multiplication; a recharge circuit that performs a recharge operation to return the photodiode after the avalanche multiplication to a state where the avalanche multiplication can be performed again, based on a first control signal including a pulse that periodically repeats a transition from a first level to a second level; a counter that is enabled based on a second control signal to count the number of times the avalanche multiplication occurs; and During a first period in which the counter is disabled by the second control signal, the first control signal maintains the first level; During a second period following the first period during which the counter is disabled by the second control signal, the first control signal transitions from the first level to the second level and from the second level to the first level; In a third period following the second period, the counter is enabled by the second control signal; The length of the first period is longer than the length of the second period. A photoelectric conversion device characterized by:

3. The recharge circuit performs the recharge operation further based on a third control signal that enables the recharge operation.

3. The photoelectric conversion device according to claim 1 or 2.

4. The recharge operation based on the third control signal is enabled before the counter is enabled based on the second control signal.

4. The photoelectric conversion device according to claim 3.

5. The recharge circuit further includes a first logic circuit that outputs a signal that controls whether the recharge operation of the recharge circuit is turned on or off based on the first control signal and the third control signal.

5. The photoelectric conversion device according to claim 3 or 4.

6. The photodiode output signal is output from the second logic circuit to the counter, and the second logic circuit outputs a signal to the counter to change the count value of the photodiode output signal.

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

7. further comprising a second logic circuit and a third logic circuit; the third logic circuit outputs a fourth control signal to the second logic circuit based on the first control signal and the second control signal; The second logic circuit outputs a signal to the counter to change the count value based on the fourth control signal and the output signal of the photodiode.

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

8. The recharge circuit performs the recharge operation further based on a fifth control signal that resets the count value of the counter.

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

9. The recharge circuit performs the recharge operation at the timing when the count value is reset.

9. The photoelectric conversion device according to claim 8.

10. a fourth logic circuit that outputs a signal that controls whether the recharge operation of the recharge circuit is turned on or off based on the first control signal, the third control signal that enables the recharge operation, and the fifth control signal.

10. The photoelectric conversion device according to claim 8 or 9.

11. The length of the period from when the recharge operation is performed until when the counter is enabled is equal to or less than the period of the pulse included in the first control signal.

11. The photoelectric conversion device according to claim 1.

12. The photoelectric conversion device according to any one of claims 1 to 11, a signal processing unit that processes a signal output from the photoelectric conversion device; An optical detection system comprising:

13. A mobile object, The photoelectric conversion device according to any one of claims 1 to 11, a distance information acquisition unit that acquires distance information to an object from a signal output from the photoelectric conversion device; a control unit that controls the moving object based on the distance information; A moving object comprising:

Images