Photoelectric conversion device and photoelectric conversion system having said photoelectric conversion device

Abstract

This photoelectric conversion device is characterized by having: a photoelectric conversion element that uses avalanche multiplication to produce a photon detection signal; a circuit that controls a first condition, in which a first terminal of the photoelectric conversion element is connected to a power source voltage, and a second condition, in which the resistance between the first terminal and the power source voltage is configured to be higher than in the first condition; a counter circuit that is connected to the photoelectric conversion element; a waveform shaping circuit that is disposed between the photoelectric conversion element and the counter circuit; and a gating circuit that is connected between an output node of the waveform shaping circuit and an input node of the counter circuit, and controls whether an output signal from the waveform shaping circuit is inputted to the counter circuit.

Description

Photoelectric conversion device and photoelectric conversion system having the photoelectric conversion device

[0001] The present invention relates to a photoelectric conversion device and a photoelectric conversion system having the photoelectric conversion device.

[0002] 2. Description of the Related Art Photoelectric conversion devices that utilize avalanche multiplication and are capable of detecting weak light at the single photon level are known.

[0003] Japanese Patent Application Laid-Open No. 2020-123847

[0004] Patent Document 1 discloses a photoelectric conversion device that performs so-called clock recharge driving. In the photoelectric conversion device described in Patent Document 1, the sensitivity of each pixel may be adjusted to, for example, low sensitivity to prevent pileup under high illuminance. In this case, there is a concern that image quality may deteriorate if the photon detection period is shortened or the clock frequency is lowered.

[0005] One aspect of the present invention is a photoelectric conversion device comprising: a photoelectric conversion element that generates a photon detection signal by avalanche multiplication; a circuit that controls a first state in which a first terminal of the photoelectric conversion element is connected to a power supply voltage; and a second state in which a resistance between the first terminal and the power supply voltage is higher than in the first state; a counter circuit connected to the photoelectric conversion element; a waveform shaping circuit arranged between the photoelectric conversion element and the counter circuit; and a gating circuit connected between an output node of the waveform shaping circuit and an input node of the counter circuit, which controls whether an output signal of the waveform shaping circuit is input to the counter circuit.

[0006] Another aspect of the present invention is a photoelectric conversion device comprising: a photoelectric conversion element that generates a photon detection signal by avalanche multiplication; a resistive element provided between a first terminal of the photoelectric conversion element and a power supply voltage; a counter circuit connected to an output node of the photoelectric conversion element; a waveform shaping circuit provided between the photoelectric conversion element and the counter circuit; and a gating circuit provided between the output node of the waveform shaping circuit and an input node of the counter circuit that controls whether an output signal of the waveform shaping circuit is input to the counter circuit, wherein during one standby state, there is a first period in which the output signal of the waveform shaping circuit is counted, and a second period in which the gating circuit is controlled not to count the output signal of the waveform shaping circuit, and the device further comprises a circuit that counts the number of first periods in which the output signal of the waveform shaping circuit is counted.

[0007] According to the present invention, it is possible to adjust the sensitivity of a photoelectric conversion device while suppressing image degradation.

[0008] FIG. 1 is a schematic configuration diagram of a photoelectric conversion device according to a first embodiment. FIG. 2 is a circuit diagram configuration example of a photoelectric conversion device according to the first embodiment. FIG. 3 is a circuit diagram configuration example of a photoelectric conversion device according to a second embodiment. FIG. 4 is an operation sequence diagram of a photoelectric conversion device according to the second embodiment. FIG. 5 is a circuit diagram configuration example of a photoelectric conversion device according to a third embodiment. FIG. 6 is an operation sequence diagram of a photoelectric conversion device according to the third embodiment. FIG. 7 is a schematic diagram of a photoelectric conversion device according to a fourth embodiment. FIG. 8 is a circuit diagram configuration example of a photoelectric conversion device according to the fourth embodiment. FIG. 9 is an operation sequence diagram of a photoelectric conversion device according to the fourth embodiment. FIG. 10 is a schematic diagram of a photoelectric conversion device according to a fifth embodiment. FIG. 11 is a circuit diagram configuration example of a photoelectric conversion device according to the fifth embodiment. FIG. 12 is an operation sequence diagram of a photoelectric conversion device according to the fifth embodiment. FIG. 13 is a functional block diagram of a photoelectric conversion system according to a sixth embodiment. FIG. 14 is a functional block diagram of a photoelectric conversion system according to a seventh embodiment. FIG. 15 is a functional block diagram of a photoelectric conversion system according to an eighth embodiment. FIG. 16 is a functional block diagram of a photoelectric conversion system according to the eighth embodiment. FIG. 17 is a functional block diagram of a photoelectric conversion system according to a ninth embodiment. FIG. 18 is a functional block diagram of a photoelectric conversion system according to a tenth embodiment. 11 is a functional block diagram of a photoelectric conversion system according to an eleventh embodiment;FIG. 12 is a functional block diagram of a photoelectric conversion system according to an eleventh embodiment;FIG.

[0009] First Embodiment A photoelectric conversion device according to a first embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a schematic diagram of one pixel of the photoelectric conversion device. Fig. 2 is a specific circuit diagram example, and Fig. 3 is an operation sequence diagram for the circuit configuration of Fig. 2.

[0010] The avalanche photodiode (APD) 101 is a photodiode that generates pairs of charges in response to incident light through photoelectric conversion. A voltage VL (first voltage) is supplied to the anode of the APD 101. A voltage VH (second voltage) higher than the voltage VL supplied to the anode is supplied to the cathode of the APD 101, and a reverse bias voltage that causes avalanche multiplication is applied to the APD 101. By supplying such a voltage, charges generated by incident light on the APD 101 undergo avalanche multiplication, generating an avalanche current.

[0011] When a reverse bias voltage is supplied to the APD 101, it operates in either Geiger mode or linear mode. In Geiger mode, the APD 101 operates by applying a voltage greater than the breakdown voltage to the anode and cathode. In linear mode, the APD 101 operates by setting the potential difference between the anode and cathode close to or equal to the breakdown voltage. An APD operated in Geiger mode is called a SPAD. For example, the voltage VL (first voltage) is −30 V, and the voltage VH (second voltage) is 1 V.

[0012] The quench element 102 is connected between a power supply that supplies a voltage VH and the cathode terminal of the APD 101. The quench element 102 functions as a load circuit during signal multiplication by avalanche multiplication, and performs a quenching operation that suppresses the voltage supplied to the APD 101 and suppresses avalanche multiplication.

[0013] The output signal of the APD 101 is input to a waveform shaping circuit 103 in the subsequent stage. The waveform shaping circuit 103 shapes the potential change of the cathode of the APD 101 when a photon is detected, and outputs a pulse signal P_ph. For example, an inverter circuit 113 is used as the waveform shaping circuit 103. While FIG. 2 shows an example in which one inverter circuit is used as the waveform shaping unit, a circuit in which multiple inverters are connected in series or another circuit that has a waveform shaping effect may also be used.

[0014] The processing circuit 104, which is provided downstream of the waveform shaping circuit 103, receives the pulse signal P_ph output from the waveform shaping circuit 103 and the judge signal P_judge output from the pulse generating circuit 106, and outputs a pulse signal P_sig. The counter circuit 105 counts the pulse signal P_sig output from the processing circuit and holds the count value. In other words, the processing circuit 104 is connected between the output node of the waveform shaping circuit 103 and the input node of the counter circuit 105, and is a gating circuit that controls whether or not the output signal of the waveform shaping circuit 103 is input to the counter circuit 105.

[0015] Fig. 2 shows an example of a specific circuit configuration that realizes the schematic configuration diagram of each pixel shown in Fig. 1. As described above, each pixel of the photoelectric conversion device shown in Fig. 2 has one inverter circuit 113 as the waveform shaping circuit 103. A pulse signal P_ph that is an output of the inverter circuit 113 and a judge signal P_judge are input to an AND circuit 114 that constitutes the processing circuit 104. The AND circuit 114 outputs the logical product of the pulse signal P_ph and the judge signal P_judge as a pulse signal P_sig.

[0016] Here, the quench element 102 has a switch 112 controlled by a clock signal P_PCLK, and drives the APD 101 with clock recharge. That is, the clock signal P_PCLK controls the APD 101 between a standby state (second state) in which avalanche multiplication is possible and a charge state (first state) in which avalanche multiplication is possible. In the charge state, the switch is on, and the cathode (first terminal) of the APD 101 is connected to the power supply voltage. In the standby state, the switch is off, and the cathode of the APD 101 is not connected to the power supply voltage. In other words, the resistance between the cathode of the APD 101 and the power supply voltage is higher than in the charge state. When a photon is incident on the APD 101 in the standby state, avalanche multiplication occurs, and the voltage V_ph drops. Thereafter, the clock signal P_PCLK is input to the switch 112, which turns the switch 112 on, charges the voltage, and returns the voltage of V_ph to its initial state.

[0017] At this time, a count period (first period) and a non-count period (second period) are defined by the clock signal P_PCLK and the judge signal P_judge. The count period is a period during which the counter circuit 105 counts the signal output from the waveform shaping circuit 103 based on the photons detected by the APD 101. The non-count period is a period during which the signal output from the waveform shaping circuit 103 is not counted. The count period is the period from the falling edge of the pulse of the clock signal P_PCLK to the falling edge of the pulse of the judge signal P_judge. The non-count period is the period from the falling edge of the pulse of the judge signal P_judge to the falling edge of the clock signal P_PCLK pulse.

[0018] 3, a clock signal P_PCLK is input to the quench element 102, and the APD enters a standby state at time t1. When a photon is incident on the APD 101 at time t2, avalanche multiplication occurs, causing V_ph to drop, and when V_ph exceeds the decision threshold, the pulse signal P_ph rises.

[0019] At time t3, when the judge signal P_judge is input to the AND circuit 114, a pulse signal P_sig, which is the logical product of the pulse signal P_ph and the judge signal P_judge, is output. At time t4, the clock signal P_PCLK is again input to the switch 112 of the quench element, and the APD 101 enters a charged state. That is, when V_ph is charged and exceeds the judgment threshold, P_ph falls.

[0020] At time t4, the APD 101 is charged, and in the next standby state period starting at time t5, the judgment signal P_judge is input to the AND circuit 114 at time t6. At this time, the pulse signal V_ph is charged with a reverse bias voltage, and the pulse signal P_ph is low. Therefore, the pulse signal P_sig output from the AND circuit 114 is also low. Thereafter, the judgment signal P_judge falls.

[0021] The input of the judge signal P_judge starts a non-count period. When a photon is incident on the APD 101 at time t7, the pulse signal P_ph rises as V_ph drops, but because the judge signal P_judge is low, the pulse signal P_sig is also low. At time t8, the clock signal P_PCLK is input, and when V_ph is charged beyond the judgment threshold, the pulse signal P_ph falls. During this standby state, no photons are incident on the APD 101 during the count period, and photons are incident on the APD 101 only during the non-count period, so photon detection signals are not counted.

[0022] In this configuration, if the pulse signal P_ph is in a high state at the timing when the judge signal P_judge is input to the processing circuit, one pulse is input to the counter circuit 105 as the pulse signal P_sig. Conversely, if the pulse signal P_ph is in a low state, the pulse signal P_sig is not input to the counter circuit 105, and counting is not performed. Therefore, the sensitivity of the pixel can be adjusted by adjusting the timing when the judge signal P_judge is input to the processing circuit 104. In other words, one standby state period has a count period in which the pulse signal P_sig is counted starting from the input of the judge signal P_judge, and a non-count period in which the pulse signal P_sig is not counted.

[0023] Conventional methods for adjusting the sensitivity of each pixel in a circuit that performs clock recharge drive include lowering the frequency of the clock signal P_PCLK and reducing the number of clock signals P_PCLK per unit time. In this case, there are concerns about a decrease in tonal range and a deterioration in the signal-to-noise ratio. Another method is to shorten the charge accumulation period while maintaining the frequency of the clock signal P_PCLK, but this creates periods during the exposure period when no charge is accumulated, which can cause image quality degradation such as the occurrence of flicker. This method allows for sensitivity adjustment of a photoelectric conversion device without causing such image quality degradation.

[0024] Second Embodiment A photoelectric conversion device according to a second embodiment will be described with reference to Figures 4 and 5. The photoelectric conversion device according to the second embodiment uses a gating circuit different from that of the photoelectric conversion device according to the first embodiment.

[0025] FIG. 4 is a specific circuit diagram illustrating an example of the photoelectric conversion device according to this embodiment. FIG. 5 is an operational sequence diagram for the circuit configuration of FIG. 4. A count period during which the counter circuit 105 counts the output signal of the waveform shaping circuit 103 and a non-count period during which the counter circuit 105 does not count the output signal of the waveform shaping circuit 103 are defined by the High and Low states of the judge signal P_judge. In the following description, the count period is defined by the period during which the judge signal P_judge is High. Note that the period during which the judge signal P_judge is High must be set to one or less times during one recharge period. This is because if the judge signal P_judge is High two or more times during the recharge period, the pulse signal P_sig may be output two or more times for one photon.

[0026] The photoelectric conversion device according to this embodiment has a D latch circuit 124 and an AND circuit 125 as the processing circuit 104. An output signal from the waveform shaping circuit is input to input G of the D latch circuit 124, and a judge signal P_judge is input to input D. The output Q and the judge signal P_judge are input to the AND circuit 125, and the output signal from the AND circuit 125 is input to the counter circuit 105 as a pulse signal P_sig. Here, when input G is High, the D latch circuit 124 outputs input D from output Q. When input G changes from High to Low, the D latch circuit 124 outputs input D from output Q immediately before the change in input G, and holds that value in output Q while input G is Low.

[0027] 5 , at time t0, a clock signal P_PCLK is input to the switch 112 of the quench element, and at time t1, the APD 101 enters a standby state. At time t2, a judge signal P_judge is input to the input D of the D latch circuit 124 and one of the input terminals of the AND circuit 125, starting the count period. When a photon is incident on the APD 101 at time t3, avalanche multiplication occurs, causing V_ph to drop, and when it exceeds the judgment threshold, the pulse signal P_ph rises. The high pulse signal P_ph is input to the input G of the D latch circuit 124. At this time, the judge signal P_judge of the input D is input as the output Q of the D latch circuit 124 to the other input terminal of the AND circuit 125. Therefore, a high pulse signal P_sig, which is the logical AND of the judge signals P_judge, is output. When the judge signal P_judge is Low, even if a photon is incident and the pulse signal P_ph becomes High, the input G of the D latch circuit 124 becomes High, but the input D is Low, so the pulse signal P_sig remains Low. Therefore, the judge signal P_judge controls the gating operation of the processing circuit 104, which functions as a gating circuit.

[0028] At time t4, another photon is incident on the APD 101. The potential of V_ph has decreased due to the avalanche multiplication caused by the photon incident on the APD 101 at time t3, and no avalanche multiplication due to the incident photon occurs at time t4.

[0029] At time t5, the judge signal P_judge falls, and the count period ends. As the judge signal P_judge falls, the pulse signal P_sig also falls.

[0030] At time t6, the clock signal P_PCLK is again input to the switch 112 of the quench element, and the APD 101 enters a charging state. That is, V_ph is charged, and when it exceeds the determination threshold, P_ph falls. During this standby state, photons are incident on the APD 101 during the count period, and therefore signals based on the detection of photons are counted.

[0031] At time t6, the APD 101 is charged, and in the next standby state period starting at time t7, the judgment signal P_judge input to the AND circuit 125 goes high at time t8, starting the count period. A high judgment signal P_judge is input to one input terminal of the AND circuit 125. At this time, V_ph is charged with a reverse bias voltage, and the pulse signal P_ph is low. That is, the input G of the D latch circuit 124 is low, and the output Q is low. The output Q is input to the other input terminal of the AND circuit 125. Therefore, the pulse signal P_sig output from the AND circuit 125 is also low.

[0032] The judge signal P_judge falls at time t9, and the count period ends. When a photon is incident on the APD 101 at time t10, V_ph falls, and when it exceeds the judgment threshold, P_ph rises.

[0033] At time t11, a clock signal P_PCLK is input to the switch 112 of the quench element, and when V_ph is charged beyond the judgment threshold, P_ph falls. Since the judge signal P_judge is low from time t9 to time t11, the pulse signal P_sig output during this period is also low. During this standby state, no photons are incident on the APD 101 during the count period, and photons are incident on the APD 101 only during the non-count period, so no photon detection signal is counted.

[0034] The next standby period begins at time t7.

[0035] With this configuration, the count period can be set at any position within one standby state period. In the configuration shown in the first embodiment, the non-count period is created by stopping the count period at a predetermined time. In other words, the count period and the non-count period are always set in this order within one standby state period. On the other hand, in this embodiment, it is possible to set a non-count period before a count period within one standby state period. Because the timing of first photon detection during the standby state period changes depending on the amount of incident light, the ability to set the count period and non-count period in this way further improves the convenience of sensitivity adjustment.

[0036] Third Embodiment A photoelectric conversion device according to a third embodiment will be described with reference to Figs. 6 and 7. In the photoelectric conversion device shown in this embodiment, a resistive element 132 is provided as the quench element 102. In this embodiment, the quench element is not controlled by a clock signal. A photoelectric conversion device using a so-called passive recharge driven SPAD will be described.

[0037] FIG. 6 is a specific example of a circuit configuration, and FIG. 7 is an operation sequence diagram for the circuit configuration of FIG. 6. When a photon is incident on the APD 101 to which a reverse bias voltage exceeding the breakdown voltage is applied, avalanche multiplication occurs, causing the voltage V_ph to drop. The avalanche operation is then stopped by the quench element 102, and the voltage V_ph returns to its initial state. This causes a pulsed signal to be input to the waveform shaping circuit. The waveform shaping circuit 103 is composed of an inverter circuit 113, which shapes the V_ph signal into a pulse signal P_ph. The pulse signal P_ph is input to the processing circuit 104. The processing circuit 104 includes a D latch circuit 134 and an AND circuit 135. As described above, the processing circuit functions as a gating circuit that controls whether or not the output signal of the waveform shaping circuit is input to the counter circuit 105, and its ON / OFF is controlled by a judge signal P_judge.

[0038] 7, when a photon is incident on the APD 101, avalanche multiplication occurs, causing V_ph to drop, and when V_ph exceeds the judgment threshold, the pulse signal P_ph rises (time t1). At this time, since the judge signal P_judge is in the high count period, the pulse signal P_sig becomes high at time t1 when the pulse signal P_ph rises.

[0039] At time t2, the judge signal P_judge goes low, and the count period ends.

[0040] At time t3 during the non-counting period, a further photon is incident on the APD 101. As V_ph drops, the pulse signal P_ph rises, but since the judge signal P_judge is low, the pulse signal P_sig is also low.

[0041] At time t4, the judge signal P_judge rises and the count period begins again. After that, photons are incident on the APD 101, and as V_ph drops, the pulse signal P_ph rises (time t5). As the pulse signal P_ph rises, the pulse signal P_sig also goes high. When V_ph returns to high due to the operation of the quench element and exceeds the judgment threshold, the pulse signal P_ph also falls. Meanwhile, because high signals continue to be input to both terminals of the AND circuit, the pulse signal P_sig remains high.

[0042] After that, at time t6, more photons are incident on the APD 101 and the pulse signal P_ph rises again, but since P_sig remains in the High state, the count value does not change.

[0043] At time t7, the judge signal P_judge falls, and the count period ends.

[0044] When capturing images in a high-illuminance environment, the interval between photon incidences may be shorter than the recharge time scale. In this case, there is a concern that the change in the voltage V_ph may not be fast enough to keep up with the incidence of photons on the APD 101, resulting in count loss and a drop in output above a certain illuminance. This embodiment is capable of counting photon detection signals while suppressing output drop even under such imaging conditions. The count period starting at time t8 will be described as an example. At time t8, the judge signal P_judge is High.

[0045] At time t9, a photon is incident on the APD 101, causing avalanche multiplication and a drop in V_ph. V_ph attempts to return to its original potential due to the action of the quench element 102, but if a new photon is incident before the potential has returned, V_ph may fall below the decision threshold and the pulse signal P_ph may be fixed at High (pile-up). In a high-illuminance environment where such pile-up continues for a long period without the processing circuit 104, only 1 is added to the counter circuit 105 during the pile-up period, causing a drop in output above a certain illuminance.

[0046] On the other hand, in this configuration, the judge signal P_judge falls at time t10, and the pulse signal P_sig also falls. Therefore, even in a high-illumination environment where pileup continues for a long period of time, the signal is added to the counter by switching the judge signal P_judge between High and Low, so no decrease in output occurs.

[0047] With this configuration, it is possible to control whether the counter circuit 105 counts the photon detection signal in response to the switching of the judge signal P_judge between High and Low. That is, it is possible to adjust the sensitivity of the photoelectric conversion device by controlling the judge signal P_judge. Furthermore, it is possible to prevent a decrease in output due to pile-up by switching P_judge between High and Low.

[0048] (Fourth Embodiment) A photoelectric conversion device according to a fourth embodiment will be described with reference to Figures 8 to 10. The photoelectric conversion device according to this embodiment has two counter circuits, and these counter circuits can count different values ​​by overlapping in time. Furthermore, the count values ​​of each counter circuit are processed and a single count value is output.

[0049] Fig. 8 is a schematic diagram of a photoelectric conversion device, Fig. 9 is a specific circuit diagram configuration example, and Fig. 10 is an operation sequence diagram in the circuit configuration of Fig. 9.

[0050] A waveform shaping circuit 103 is connected to the cathode terminal of the APD 101, which is connected between the power supplies VL and VH. A pulse signal P_ph, which is an output signal of the waveform shaping circuit 103, is divided into a path that is input to a first counter circuit 145 via a processing circuit 104 and a path that is input directly to a second counter circuit 146. Here, the signal input to the first counter circuit 145 is called P_sig1, and the signal input to the second counter circuit 146 is called P_sig2. A judge signal P_judge output from the pulse generating circuit 106 is input to the processing circuit 104.

[0051] The first count value OUT1, which is the output of the first counter circuit 145, is used to count the photon detection signals during the count period limited by the judge signal P_judge. On the other hand, the second count value OUT2, which is the output signal of the second counter circuit 146, is used to count all the photon detection signals. The first count value OUT1 and the second count value OUT2 are each input to a common output signal processing circuit 147. The output signal processing circuit 147 can, for example, compare or combine the first count value OUT1 and the second count value OUT2. As shown in FIG. 9 , an inverter 113 is provided as the waveform shaping circuit 103, and an AND circuit 114 is provided as the processing circuit 104.

[0052] 10, a judgment signal P_judge is input for each standby period from when one of the clock signals P_CLK is input to the switch 112 of the quench element until the next clock is input, thereby separating each standby period into a count period and a non-count period.

[0053] With this configuration, it is possible to count outputs with different sensitivities that overlap in time from the same photon detection signal, and output more suitable count information from the output signal processing circuit 147. For example, by outputting the larger count value of the first count value OUT1 or the second count value OUT2 that has not reached the upper count limit of the counter circuit 145 or the counter circuit 146, it is possible to obtain an image with a higher S / N ratio in which whiteout is suppressed.

[0054] Fifth Embodiment A modification of the configuration of the fourth embodiment described above will be described as a fifth embodiment in Figures 11 to 13. The difference from the configurations shown in Figures 8 to 11 is that each pixel has two processing circuits, each corresponding to a counter circuit.

[0055] Fig. 11 is a schematic diagram of a photoelectric conversion device, Fig. 12 is a specific circuit diagram configuration example, and Fig. 13 is an operation sequence diagram in the circuit configuration of Fig. 12.

[0056] The pulse signal P_ph, which is the output signal of the waveform shaping circuit, is split into a path that is input to the first counter circuit 145 via the first processing circuit 154 and a path that is input to the second counter circuit 146 via the second processing circuit 155. A judge signal P_judge1 is input to the first processing circuit 154, and a judge signal P_judge2 is output to the second processing circuit 155. The pulse signal P_sig1, which is the output signal of the first processing circuit 154, is input to the output signal processing circuit 147 as OUT1 via the first counter circuit 145. The pulse signal P_sig2, which is the output signal of the second processing circuit 155, is input to the output signal processing circuit 147 as OUT2 via the second counter circuit 146. The quench element 102 has a switch 112, and the waveform shaping circuit 103 is, for example, an inverter circuit 113. The first processing circuit 154 and the second processing circuit 155 may be a first AND circuit 164 and a second AND circuit 165, respectively.

[0057] In this configuration, the first processing circuit 154 and the second processing circuit 155 can be controlled by separate judge signals P_judge. That is, the same photon detection signal can be simultaneously counted as outputs with different sensitivities, and more suitable count information can be output by the output signal processing circuit 147. By using two processing circuits and the judge signal P_judge, signal information can be acquired under a greater number of condition combinations.

[0058] Sixth Embodiment A photoelectric conversion system using the photoelectric conversion device according to each of the above-described embodiments will be described with reference to Fig. 14. Fig. 14 is a block diagram showing a schematic configuration of the photoelectric conversion system according to this embodiment.

[0059] The processing device according to the sixth embodiment includes a control unit 401 , a timing adjustment unit 402 , an image acquisition unit 403 , a readout unit 404 , a gain adjustment unit 405 , a nonlinear correction unit 406 , a defect correction unit 407 , a data compression unit 408 , and a memory unit 409 .

[0060] The image acquisition unit 403 is, for example, the APD 101, and the readout unit 404 is, for example, provided subsequent to the counter circuit 105. The control unit 401 may be a control unit inside the photoelectric conversion device, or may be external to the photoelectric conversion device. The image acquisition unit 403 is controlled by a timing adjustment unit 402 controlled by the control unit 401. The image data generated by the image acquisition unit is input to a storage unit 409 after undergoing correction processing. Note that the order of correction processing is not limited to the order shown in FIG. 14 .

[0061] The gain adjustment unit 405 is provided between the readout unit 404 and the nonlinear correction unit 406 and applies a digital gain to the image data generated by the image acquisition unit 403. Data for image correction often contains decimal values, but if the image output is an integer, quantization error can reduce the correction accuracy. By applying a gain to the image data in advance, the effects of quantization error can be suppressed and the correction accuracy can be improved. If the quantization error can be suppressed to ¼ of the single-photon signal level or less, the corrected image will appear visually natural. Therefore, it is desirable that the digital gain applied to the image data be, for example, 4 times or more.

[0062] The nonlinear correction unit 406 is disposed between the gain adjustment unit 405 and the defect correction unit 407, and corrects the image data under the control of the control unit 401. As described in the above embodiments, when the image acquisition unit 403 is a photon-counting detector, the optical response often becomes nonlinear due to the influence of dead time. When affected by a nonlinear optical response, correction based on a linear response may result in overcorrection. Therefore, by performing nonlinear correction on the image data prior to the calculation processing in the defect correction unit 407, overcorrection can be prevented, and appropriate nonlinear correction can be performed according to the drive timing. This nonlinear correction is performed using, for example, a LookUp Table.

[0063] The defect correction unit 407 corrects the data of defective pixels contained in the image data. As a specific example, the output value of the defective pixel is extracted and the position information and output value of the defective pixel are identified. There are methods for replacing the output value with the average value or median value of the outputs of the pixels surrounding the identified defective pixel, and methods for dividing the estimated defective image data.

[0064] The data compression unit 408 compresses the corrected image data. The photoelectric conversion device according to the present invention generates a huge amount of image data corresponding to a high dynamic range. By providing the data compression unit 408, the data can be compressed before being stored in the subsequent storage unit 409.

[0065] The storage unit 409 is a storage unit that holds at least a part of the image data generated in the previous stage. Specifically, the image data is stored in a memory such as an SRAM, a DRAM, or a nonvolatile memory.

[0066] As described above, according to this embodiment, a photoelectric conversion system can be realized to which the photoelectric conversion device shown in any of the above-described embodiments is applied.

[0067] Seventh Embodiment A photoelectric conversion system according to this embodiment will be described with reference to Fig. 15. Fig. 15 is a block diagram showing a schematic configuration of the photoelectric conversion system according to this embodiment.

[0068] The photoelectric conversion device described in the above embodiment can be applied to various photoelectric conversion systems. Examples of applicable photoelectric conversion systems include digital still cameras, digital camcorders, surveillance cameras, copiers, fax machines, mobile phones, vehicle-mounted cameras, and observation satellites. Camera modules equipped with an optical system such as a lens and an imaging device are also included in photoelectric conversion systems. Figure 13 illustrates a block diagram of a digital still camera as an example of such systems.

[0069] 15 includes an image pickup device 1004, which is an example of a photoelectric conversion device, and a lens 1002 that forms an optical image of a subject on the image pickup device 1004. The photoelectric conversion system further includes an aperture 1003 that adjusts the amount of light passing through the lens 1002, and a barrier 1001 that protects the lens 1002. The lens 1002 and aperture 1003 form an optical system that focuses light on the image pickup device 1004. The image pickup device 1004 is a photoelectric conversion device according to any of the above embodiments, and converts the optical image formed by the lens 1002 into an electrical signal.

[0070] The photoelectric conversion system includes a signal processing unit 1007, which is an image generation unit that generates an image by processing an output signal output from an imaging device 1004. The signal processing unit 1007 performs various corrections and compressions as necessary to output image data. The signal processing unit 1007 may be formed in the same semiconductor layer as the imaging device 1004, or may be formed in a different semiconductor layer from the imaging device 1004. Furthermore, the imaging device 1004 and the signal processing unit 1007 may be formed in the same semiconductor layer.

[0071] The photoelectric conversion system further includes a memory unit 1010 for temporarily storing image data, and an external interface unit (external I / F unit) 1013 for communicating with an external computer or the like. The photoelectric conversion system further includes a recording medium 1012 such as a semiconductor memory for recording or reading out image data, and a recording medium control interface unit (recording medium control I / F unit) 1011 for recording or reading out data from the recording medium 1012. The recording medium 1012 may be built into the photoelectric conversion system or may be detachable.

[0072] The photoelectric conversion system further includes an overall control / calculation unit 1009 that performs various calculations and controls the entire digital still camera, and a timing generation unit 1008 that outputs various timing signals to the image capture device 1004 and the signal processing unit 1007. Here, timing signals and the like may be input from outside, and the photoelectric conversion system only needs to include at least the image capture device 1004 and the signal processing unit 1007 that processes the output signal output from the image capture device 1004.

[0073] The imaging device 1004 outputs an imaging signal to the signal processing unit 1007. The signal processing unit 1007 performs predetermined signal processing on the imaging signal output from the imaging device 1004 and outputs image data. The signal processing unit 1007 generates an image using the imaging signal.

[0074] As described above, according to this embodiment, it is possible to realize a photoelectric conversion system to which the photoelectric conversion device (image pickup device) according to any one of the above embodiments is applied.

[0075] Eighth Embodiment A photoelectric conversion system and a moving object according to this embodiment will be described with reference to Fig. 16A and Fig. 16B. Fig. 16A and Fig. 16B are diagrams showing the configurations of the photoelectric conversion system and the moving object according to this embodiment.

[0076] FIG. 16A illustrates an example of a photoelectric conversion system for an in-vehicle camera. The photoelectric conversion system 2300 includes an image capture device 2310. The image capture device 2310 is the photoelectric conversion device described in any of the above embodiments. The photoelectric conversion system 2300 also includes an image processing unit 2312 that performs image processing on multiple pieces of image data acquired by the image capture device 2310. The photoelectric conversion system 2300 also includes a parallax acquisition unit 2314 that calculates parallax (phase difference between parallax images) from the multiple pieces of image data acquired by the photoelectric conversion system 2300. The photoelectric conversion system 2300 also includes a distance acquisition unit 2316 that calculates the distance to an object based on the calculated parallax, and a collision determination unit 2318 that determines whether or not there is a possibility of a collision based on the calculated distance. Here, the parallax acquisition unit 2314 and the distance acquisition unit 2316 are examples of distance information acquisition means that acquire distance information to the object. That is, distance information may be acquired using not only the phase difference but also ToF (Time Of Flight) technology. The collision determination unit 2318 may determine the possibility of a collision using any of these distance information. The distance information acquisition means may be realized by dedicated hardware or a software module. Furthermore, it may be realized by a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), or the like, or a combination thereof.

[0077] The photoelectric conversion system 2300 is connected to a vehicle information acquisition device 2320 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The photoelectric conversion system 2300 is also connected to a control ECU 2330, which is a control device (control unit) that outputs a control signal to generate a braking force for the vehicle based on the determination result of the collision determination unit 2318. The photoelectric conversion system 2300 is also connected to an alarm device 2340 that issues an alarm to the driver based on the determination result of the collision determination unit 2318. For example, if the determination result of the collision determination unit 2318 indicates a high collision possibility, the control ECU 2330 performs vehicle control to avoid the collision and mitigate damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 2340 warns the user by sounding an alarm, displaying alarm information on the screen of a car navigation system, etc., or vibrating the seat belt or steering wheel.

[0078] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are imaged by the photoelectric conversion system 2300. Fig. 16B shows the photoelectric conversion system when imaging the area in front of the vehicle (imaging range 2350). The vehicle information acquisition device 2320 sends instructions to the photoelectric conversion system 2300 or the imaging device 2310. This configuration can further improve the accuracy of distance measurement.

[0079] Although the above describes an example of control to prevent collision with other vehicles, the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from a lane, etc. Furthermore, the photoelectric conversion system 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 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).

[0080] Ninth Embodiment A photoelectric conversion system according to this embodiment will be described with reference to Fig. 17. Fig. 17 is a block diagram showing an example of the configuration of a range image sensor that is a photoelectric conversion system.

[0081] 17, the distance image sensor 1401 is configured to include an optical system 1402, a photoelectric conversion device 1403, an image processing circuit 1404, a monitor 1405, and a memory 1406. The distance image sensor 1401 receives light (modulated light or pulsed light) that is projected toward the subject from a light source device 1411 and reflected from the surface of the subject, thereby obtaining a distance image according to the distance to the subject.

[0082] The optical system 1402 is configured to have one or more lenses, and guides image light (incident light) from an object to the photoelectric conversion device 1403 , forming an image on the light receiving surface (sensor portion) of the photoelectric conversion device 1403 .

[0083] The photoelectric conversion device 1403 is the photoelectric conversion device described in the above-mentioned embodiment, and a distance signal indicating the distance determined from the light receiving signal output from the photoelectric conversion device 1403 is supplied to the image processing circuit 1404.

[0084] The image processing circuit 1404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 1403. The distance image (image data) obtained by this image processing is then supplied to a monitor 1405 for display, or supplied to a memory 1406 for storage (recording).

[0085] In the range image sensor 1401 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.

[0086] Tenth Embodiment A photoelectric conversion system according to this embodiment will be described with reference to Fig. 18. Fig. 18 is a diagram showing an example of the schematic configuration of an endoscopic surgery system, which is the photoelectric conversion system according to this embodiment.

[0087] 18 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 is composed of an endoscope 1100, a surgical tool 1110, and a cart 1134 on which various devices for endoscopic surgery are mounted.

[0088] The endoscope 1100 is composed of 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. In the illustrated example, the endoscope 1100 is configured as a so-called rigid lens barrel having a rigid lens barrel 1101, but the endoscope 1100 may also be configured as a so-called flexible lens barrel having a flexible lens barrel.

[0089] 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, and 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 toward an observation target inside a body cavity of a patient 1132. The endoscope 1100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0090] An optical system and a photoelectric conversion device are provided inside the camera head 1102, and light reflected from an observation target (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 the photoelectric conversion device described in the above-described embodiment. The image signal is transmitted to a camera control unit (CCU) 1135 as RAW data.

[0091] 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 types of image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0092] 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 .

[0093] The light source device 1203 is configured from 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.

[0094] 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.

[0095] 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.

[0096] The light source device 1203, which supplies illumination light to the endoscope 1100 when photographing the surgical site, can be configured from a white light source formed, for example, by an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, allowing the light source device 1203 to adjust the white balance of the captured image. In this case, it is also possible to time-share images corresponding to each RGB by irradiating the object of observation with laser light from each RGB laser light source in a time-division manner and controlling the drive of the image sensor of the camera head 1102 in synchronization with the irradiation timing. This method allows color images to be obtained without providing a color filter to the image sensor.

[0097] Furthermore, the light source device 1203 may be controlled to change the intensity of light it outputs 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 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.

[0098] The light source device 1203 may also be configured to provide light in a predetermined wavelength band corresponding to special light observation. Special light observation utilizes, 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 during normal observation, a specific tissue, such as a blood vessel on the surface of a mucous membrane, can be imaged 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 may involve irradiating excitation light onto a body tissue and observing the fluorescence from the body tissue, or by 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 may be configured to provide narrow-band light and / or excitation light corresponding to such special light observation.

[0099] Eleventh Embodiment A photoelectric conversion system according to this embodiment will be described with reference to FIGS. 19A and 19B. FIG. 19A is a diagram showing an example of the configuration of glasses 1600 (smart glasses) which are a photoelectric conversion system. The glasses 1600 have a photoelectric conversion device 1602. The photoelectric conversion device 1602 is the photoelectric conversion device described in the twelfth embodiment above. A display device including a light-emitting device such as an OLED or LED may be provided on the back side of the lens 1601. There may be one or more photoelectric conversion devices 1602. A combination of multiple types of photoelectric conversion devices may also be used. The arrangement position of the photoelectric conversion device 1602 is not limited to that shown in FIG. 19A.

[0100] 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. 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.

[0101] FIG. 19B illustrates 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 an optical system for projecting light emitted from the photoelectric conversion device and 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 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 with a light-receiving element detects the reflected light of the emitted infrared light from the eyeball, thereby obtaining an image of the eyeball. A reduction unit for reducing light from the infrared light emitter to the display unit in a planar view reduces degradation of image quality.

[0102] The gaze of the user relative to the displayed image is detected from an image of the eyeball obtained by capturing infrared light. Any known method can be used for gaze detection using the 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.

[0103] 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.

[0104] 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.

[0105] 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 may be determined by an external control device and received. 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.

[0106] The display area may include a first display area and a second display area different from the first display area, and 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 may be determined by an external control device and received. 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.

[0107] Note that AI may be used to determine the first field of view area or 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 included in the display device, the photoelectric conversion device, or an external device. If included in the external device, it is transmitted to the display device via communication.

[0108] When display control is performed based on visual recognition detection, the present invention is preferably applied to smart glasses that further include a photoelectric conversion device for capturing images of the outside world. The smart glasses can display captured external information in real time.

[0109] The above-described embodiments can be modified as appropriate without departing from the scope of the technical concept. Furthermore, examples in which part of the configuration of one embodiment is added to another embodiment, or examples in which part of the configuration of another embodiment is replaced with another embodiment, are also included in the embodiments of the present invention.

[0110] The disclosure of the present embodiment also includes the following configurations and methods.

[0111] (Configuration 1) A photoelectric conversion device comprising: a photoelectric conversion element that generates a photon detection signal by avalanche multiplication; a circuit that controls a first state in which a first terminal of the photoelectric conversion element is connected to a power supply voltage; and a second state in which a resistance between the first terminal and the power supply voltage is higher than in the first state; a counter circuit connected to the photoelectric conversion element; and a waveform shaping circuit disposed between the photoelectric conversion element and the counter circuit; and a gating circuit connected between an output node of the waveform shaping circuit and an input node of the counter circuit, for controlling whether an output signal of the waveform shaping circuit is input to the counter circuit.

[0112] (Configuration 2) The photoelectric conversion device according to Configuration 1, characterized in that during one standby state, there is a first period in which the output signal of the waveform shaping circuit is counted, and a second period in which the gating circuit is controlled not to count the output signal of the waveform shaping circuit.

[0113] (Configuration 3) The photoelectric conversion device according to configuration 1 or 2, wherein the second state is a state in which the first terminal and the power supply voltage are not connected.

[0114] (Configuration 4) A photoelectric conversion device according to any one of configurations 1 to 3, further comprising a pulse generating circuit, the pulse generating circuit outputting a judgment signal that controls whether the gating circuit counts the output signal of the waveform shaping circuit.

[0115] (Configuration 5) The photoelectric conversion device according to configuration 4, wherein the signal output from the waveform shaping circuit and the judgment signal are input to the gating circuit.

[0116] (Configuration 6) The photoelectric conversion device according to Configuration 5, wherein one count period of the counter circuit is a period from the start of the second state to the input of a pulse of the judgment signal to the gating circuit.

[0117] (Configuration 7) The photoelectric conversion device according to configuration 5, wherein the gating circuit includes an AND circuit, and the output signal of the waveform shaping circuit and the judgment signal are input to the AND circuit.

[0118] (Configuration 8) The photoelectric conversion device according to configuration 5, wherein the period of counting by the counter circuit is defined by the period during which the level of the judgment signal is High or the period during which the level of the judgment signal is Low.

[0119] (Configuration 9) The photoelectric conversion device according to configuration 8, wherein the processing circuit includes a D latch, and the output signal of the waveform shaping circuit and the judgment signal are input to the D latch.

[0120] (Configuration 10) The photoelectric conversion device according to any one of configurations 1 to 9, further comprising a second counter circuit connected to the output node of the photoelectric conversion element.

[0121] (Configuration 11) The photoelectric conversion device according to Configuration 10, wherein the counter circuit outputs a first count value and the second counter circuit outputs a second count value in response to an input of a single output signal from the waveform shaping circuit, and the counting of the first count value and the second count value overlaps in time.

[0122] (Configuration 12) The photoelectric conversion device according to configuration 11, further comprising a signal processing circuit that processes the first count value and the second count value and outputs one count value.

[0123] (Configuration 13) A photoelectric conversion device comprising: a photoelectric conversion element that generates a photon detection signal by avalanche multiplication; a resistive element provided between a first terminal of the photoelectric conversion element and a power supply voltage; and a counter circuit connected to an output node of the photoelectric conversion element. A waveform shaping circuit is provided between the photoelectric conversion element and the counter circuit; and a gating circuit is provided between the output node of the waveform shaping circuit and an input node of the counter circuit that controls whether an output signal of the waveform shaping circuit is input to the counter circuit. During one standby state, there is a first period during which the output signal of the waveform shaping circuit is counted, and a second period during which the gating circuit is controlled not to count the output signal of the waveform shaping circuit. The photoelectric conversion device further comprises a circuit that counts the number of first periods during which the output signal of the waveform shaping circuit is counted.

[0124] (Configuration 14) The photoelectric conversion device according to configuration 13, wherein the resistive element is a quenching element.

[0125] (Configuration 15) The photoelectric conversion device according to configuration 14, further comprising a pulse generating circuit, the pulse generating circuit outputting a judgment signal that controls whether the gating circuit counts the output signal of the waveform shaping circuit.

[0126] (Configuration 16) The photoelectric conversion device according to configuration 15, wherein the signal output from the waveform shaping circuit and the judgment signal are input to the gating circuit.

[0127] (Configuration 17) The photoelectric conversion device according to configuration 16, wherein the period of counting by the counter circuit is defined by the period during which the level of the judgment signal is High or the period during which the level of the judgment signal is Low.

[0128] (Configuration 18) The photoelectric conversion device according to configuration 17, wherein the processing circuit includes a D latch, and the output signal of the waveform shaping circuit and the judgment signal are input to the D latch.

[0129] (Configuration 19) A photoelectric conversion system comprising: the photoelectric conversion device according to any one of configurations 1 to 18; and a signal processing unit that generates an image using a signal output from the photoelectric conversion device.

[0130] (Configuration 20) A moving body including the photoelectric conversion device according to any one of configurations 1 to 18, characterized in that the moving body has a control unit that controls movement of the moving body using a signal output by the photoelectric conversion device.

[0131] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0132] This application claims priority based on Japanese Patent Application No. 2023-108683, filed on June 30, 2023, the entire contents of which are incorporated herein by reference.

[0133] 101 Avalanche photodiode 102 Quench element 105 Counter circuit 103 Waveform shaping circuit 104 Processing circuit

Claims

1. A photoelectric conversion device comprising: a photoelectric conversion element that generates a photon detection signal by avalanche multiplication; a circuit that controls a first state in which a first terminal of the photoelectric conversion element is connected to a power supply voltage, and a second state in which a higher resistance is provided between the first terminal and the power supply voltage than in the first state; a counter circuit connected to the photoelectric conversion element; a waveform shaping circuit arranged between the photoelectric conversion element and the counter circuit; and a gating circuit connected between an output node of the waveform shaping circuit and an input node of the counter circuit, for controlling whether or not an output signal of the waveform shaping circuit is input to the counter circuit.

2. The photoelectric conversion device according to claim 1, characterized in that during one standby state, there is a first period in which the output signal of the waveform shaping circuit is counted, and a second period in which the gating circuit is controlled not to count the output signal of the waveform shaping circuit.

3. The photoelectric conversion device according to claim 1, wherein the second state is such that the first terminal is not connected to the power supply voltage.

4. A photoelectric conversion device as described in claim 1, further comprising a pulse generating circuit, said pulse generating circuit outputting a judgment signal that controls whether said gating circuit counts the output signal of said waveform shaping circuit.

5. The photoelectric conversion device according to claim 4, wherein the signal output from the waveform shaping circuit and the judgment signal are input to the gating circuit.

6. The photoelectric conversion device according to claim 5, wherein one count period of the counter circuit is the period from the start of the second state to the input of a pulse of the judgment signal to the gating circuit.

7. The photoelectric conversion device according to claim 5, wherein the gating circuit includes an AND circuit, and the output signal of the waveform shaping circuit and the judgment signal are input to the AND circuit.

8. The photoelectric conversion device according to claim 5, wherein the period of counting by said counter circuit is defined by the period during which the level of said judge signal is High or the period during which the level of said judge signal is Low.

9. The photoelectric conversion device according to claim 8, wherein the processing circuit includes a D latch, and the output signal of the waveform shaping circuit and the judge signal are input to the D latch.

10. The photoelectric conversion device according to claim 1, further comprising a second counter circuit connected to an output node of said photoelectric conversion element.

11. The photoelectric conversion device according to claim 10, characterized in that, in response to an input of an output signal from a single waveform shaping circuit, the counter circuit outputs a first count value and the second counter circuit outputs a second count value, and the counting of the first count value and the second count value is performed in a time-overlapping manner.

12. The photoelectric conversion device according to claim 11, further comprising a signal processing circuit for processing the first count value and the second count value and outputting one count value.

13. A photoelectric conversion device comprising: a photoelectric conversion element which generates a photon detection signal by avalanche multiplication; a resistive element provided between a first terminal of said photoelectric conversion element and a power supply voltage; a counter circuit connected to an output node of said photoelectric conversion element; a waveform shaping circuit provided between said photoelectric conversion element and said counter circuit; and a gating circuit provided between the output node of said waveform shaping circuit and an input node of said counter circuit which controls whether or not an output signal of said waveform shaping circuit is input to said counter circuit, wherein during one standby state, there is a first period during which the output signal of said waveform shaping circuit is counted, and a second period during which the gating circuit is controlled not to count the output signal of the waveform shaping circuit, and a circuit which counts the number of first periods during which the output signal of said waveform shaping circuit is counted.

14. The photoelectric conversion device according to claim 13, wherein the resistive element is a quench element.

15. A photoelectric conversion device according to claim 14, further comprising a pulse generating circuit, said pulse generating circuit outputting a judgment signal for controlling whether or not said gating circuit counts the output signal of said waveform shaping circuit.

16. The photoelectric conversion device according to claim 15, wherein the signal output from the waveform shaping circuit and the judgment signal are input to the gating circuit.

17. The photoelectric conversion device according to claim 16, wherein the period of counting by said counter circuit is defined by the period during which the level of said judgment signal is High or the period during which the level of said judgment signal is Low.

18. The photoelectric conversion device according to claim 17, wherein the processing circuit includes a D latch, and the output signal of the waveform shaping circuit and the judge signal are input to the D latch.

19. A photoelectric conversion system comprising: a photoelectric conversion device according to any one of claims 1 to 18; and a signal processing unit that generates an image using a signal output by the photoelectric conversion device.

20. A moving body including a photoelectric conversion device according to any one of claims 1 to 18, characterized in that the moving body has a control unit that controls the movement of the moving body using a signal output by the photoelectric conversion device.

Images