Photoelectric conversion device

Abstract

To achieve both high spatial resolution and prevention of aliasing.SOLUTION: A photoelectric conversion device has a pixel area in which a plurality of pixels is arranged in an array shape, the pixels including a first pixel including a first photoelectric conversion unit, a first detection circuit that outputs a first detection signal based on photons incident on the first photoelectric conversion unit, a first output circuit that outputs a first pixel signal to the outside of the pixel according to the first detection signal, and a first control circuit that controls whether to input the first detection signal to the first output circuit, and a second pixel including a second photoelectric conversion unit, a second detection circuit that outputs a second detection signal based on photons incident on the second photoelectric conversion unit, a second output circuit that outputs a second pixel signal to the outside of the pixel according to the second detection signal, and a second control circuit that controls whether to input the second detection signal to the second output circuit. The first control circuit controls whether to input the first detection signal to the first output circuit according to the second detection signal.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] The TOF (Time-Of-Flight) method is often used to measure the distance to a measurement target. Patent Document 1 discloses a TOF distance measuring device using APDs (Avalanche Photo Diodes). Adjacent APDs are grouped together, and a pulse signal is output when a certain number of APDs in the group detect signals at close timing. This makes it possible to selectively detect signals with strong temporal and spatial correlation and suppress the influence of external light, which has weak temporal and spatial correlation, on signals. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2014-059302 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, there is a problem that grouping a plurality of APDs reduces the spatial resolution of the detection device.

[0005] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a photoelectric conversion device and an imaging system that achieve both high spatial resolution and suppression of aliasing. [Means for solving the problem]

[0006] One aspect of the present invention is a photoelectric conversion device having a pixel region in which a plurality of pixels are arranged in an array, the pixel region including a first pixel including a first photoelectric conversion unit, a first detection circuit that outputs a first detection signal based on photons incident on the first photoelectric conversion unit, a first output circuit that outputs a first pixel signal outside the pixel in response to the first detection signal, and a first control circuit that controls whether or not the first detection signal is input to the first output circuit; and a second pixel including a second photoelectric conversion unit, a second detection circuit that outputs a second detection signal based on photons incident on the second photoelectric conversion unit, a second output circuit that outputs a second pixel signal outside the pixel in response to the second detection signal, and a second control circuit that controls whether or not the second detection signal is input to the second output circuit, and the first control circuit controls whether or not the first detection signal is input to the first output circuit in response to the second detection signal. [Effects of the Invention]

[0007] According to the present invention, it is possible to achieve both high spatial resolution and suppression of aliasing. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a photoelectric conversion device according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram of a PD substrate of the photoelectric conversion device according to the embodiment. [Figure 3] FIG. 2 is a schematic diagram of a circuit board of a photoelectric conversion device according to an embodiment. [Figure 4] 2 is a configuration example of a pixel circuit of a photoelectric conversion device according to an embodiment. [Figure 5] FIG. 2 is a schematic diagram illustrating driving of a pixel circuit of a photoelectric conversion device according to an embodiment. [Figure 6] FIG. 10 is a block diagram of two pixels according to a comparative example of the first embodiment. [Figure 7] FIG. 2 is a block diagram of two pixels according to the first embodiment. [Figure 8] FIG. 2 is a circuit diagram for one pixel according to the first embodiment. [Figure 9] FIG. 3 is a timing diagram of pixel driving according to the first embodiment. [Figure 10] FIG. 2 is a diagram illustrating a control relationship of the pixel array according to the first embodiment. [Figure 11] FIG. 10 is a circuit diagram for one pixel according to the second embodiment. [Figure 12] FIG. 10 is a timing chart of pixel driving according to the second embodiment. [Figure 13] FIG. 10 is a circuit diagram for one pixel according to a third embodiment. [Figure 14] FIG. 10 is a timing chart of pixel driving according to the third embodiment. [Figure 15] FIG. 10 is a diagram illustrating a control relationship of a pixel array according to a third embodiment. [Figure 16] FIG. 11 is a diagram illustrating a control relationship of a pixel array according to a modified example of the third embodiment. [Figure 17] FIG. 10 is a circuit diagram for one pixel according to a fourth embodiment. [Figure 18] FIG. 10 is a timing chart of pixel driving according to the fourth embodiment. [Figure 19] FIG. 11 is a diagram illustrating a control relationship of a pixel array according to a fifth embodiment. [Figure 20] FIG. 13 is a diagram illustrating a control relationship of a pixel array according to a modified example of the fifth embodiment. [Figure 21] FIG. 10 is a functional block diagram of a photoelectric conversion system according to a sixth embodiment. [Figure 22] FIG. 13 is a functional block diagram of a photoelectric conversion system according to a seventh embodiment. [Figure 23] FIG. 13 is a functional block diagram of a photoelectric conversion system according to an eighth embodiment. [Figure 24] FIG. 13 is a functional block diagram of a photoelectric conversion system according to a ninth embodiment. [Figure 25] FIG. 20 is a functional block diagram of a photoelectric conversion system according to a tenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, "upper," "lower," "right," "left," and other terms including these terms) will be used as necessary. The use of these terms is intended to facilitate understanding of the embodiments with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention.

[0011] In this specification, a planar view refers to a view from a direction perpendicular to the light incident surface of the semiconductor layer. A cross-sectional view refers to a surface perpendicular to the light incident surface of the semiconductor layer. When the light incident surface of the semiconductor layer is a rough surface when viewed microscopically, the planar view is defined based on the light incident surface of the semiconductor layer when viewed macroscopically.

[0012] In the following description, the anode of the APD (avalanche photodiode) is set to a fixed potential, and a signal is extracted from the cathode side. Therefore, the first conductivity type semiconductor region, which has majority carriers of charges with the same polarity as the signal charge, is an N-type semiconductor region, and the second conductivity type semiconductor region, which has majority carriers of charges with a polarity opposite to that of the signal charge, is a P-type semiconductor region. The present invention also applies when the cathode of the APD is set to a fixed potential and a signal is extracted from the anode side. In this case, the first conductivity type semiconductor region, which has majority carriers of charges with the same polarity as the signal charge, is a P-type semiconductor region, and the second conductivity type semiconductor region, which has majority carriers of charges with a polarity opposite to that of the signal charge, is an N-type semiconductor region. While the following description focuses on a case where one node of the APD is set to a fixed potential, the potentials of both nodes may fluctuate.

[0013] In this specification, when the term "impurity concentration" is used simply, it means the net impurity concentration minus the amount compensated for by impurities of the opposite conductivity type. In other words, "impurity concentration" refers to the NET doping concentration. A region where the P-type doped impurity concentration is higher than the N-type doped impurity concentration is a P-type semiconductor region. Conversely, a region where the N-type doped impurity concentration is higher than the P-type doped impurity concentration is an N-type semiconductor region.

[0014] A configuration common to each embodiment of a photoelectric conversion device and a driving method thereof according to the present invention will be described with reference to FIGS. 1 to 5. FIG.

[0015] FIG. 1 is a diagram showing the configuration of a stacked-type photoelectric conversion device 100 according to an embodiment of the present invention. The photoelectric conversion device 100 is configured by stacking and electrically connecting two substrates, a sensor substrate 11 and a circuit substrate 21. The sensor substrate 11 has a first semiconductor layer having a photoelectric conversion element 102 (described later) and a first wiring structure. The circuit substrate 21 has a second semiconductor layer having circuits such as a signal processing unit 103 (described later) and a second wiring structure. The photoelectric conversion device 100 is configured by stacking the second semiconductor layer, the second wiring structure, the first wiring structure, and the first semiconductor layer in this order. The photoelectric conversion device described in each embodiment is a back-illuminated photoelectric conversion device in which light is incident from a first surface and a circuit substrate is disposed on a second surface.

[0016] In the following description, the sensor substrate 11 and the circuit substrate 21 are described as diced chips, but are not limited to chips. For example, each substrate may be a wafer. Furthermore, each substrate may be stacked in the wafer state and then diced, or may be chipped and then stacked and bonded.

[0017] The sensor substrate 11 has a pixel region 12 arranged thereon, and the circuit substrate 21 has a circuit region 22 arranged thereon for processing signals detected in the pixel region 12 .

[0018] 2 is a diagram showing an example of the arrangement of the sensor substrate 11. Pixels 101, each having a photoelectric conversion element 102 including an APD, are arranged in a two-dimensional array in a plan view to form a pixel region 12.

[0019] The pixel 101 is typically a pixel for forming an image, but when used for TOF (Time of Flight), it does not necessarily have to form an image. In other words, the pixel 101 may be a pixel for measuring the time and amount of light that arrives.

[0020] 3 is a configuration diagram of the circuit board 21. It has a signal processing unit 103 that processes the charges photoelectrically converted by the photoelectric conversion element 102 in FIG. 2, a readout circuit 112, a control pulse generation unit 115, a horizontal scanning circuit unit 111, a signal line 113, and a vertical scanning circuit unit 110.

[0021] The photoelectric conversion element 102 in FIG. 2 and the signal processing unit 103 in FIG. 3 are electrically connected via connection wiring provided for each pixel.

[0022] The vertical scanning circuit unit 110 receives a control pulse supplied from the control pulse generating unit 115 and supplies the control pulse to each pixel. The vertical scanning circuit unit 110 uses logic circuits such as a shift register and an address decoder.

[0023] The signal output from the photoelectric conversion element 102 of the pixel is processed by the signal processing unit 103. The signal processing unit 103 is provided with a counter, a memory, etc., and the memory holds digital values.

[0024] The horizontal scanning circuit unit 111 inputs a control pulse to the signal processing unit 103 to sequentially select each column in order to read out the signal from the memory of each pixel in which the digital signal is held.

[0025] A signal is output to the signal line 113 from the signal processing unit 103 of the pixel selected by the vertical scanning circuit unit 110 for the selected column.

[0026] The signal output to the signal line 113 is output via an output circuit 114 to a recording unit or a signal processing unit outside the photoelectric conversion device 100 .

[0027] 2, the photoelectric conversion elements may be arranged one-dimensionally in the pixel region. The function of the signal processing unit does not necessarily need to be provided for each photoelectric conversion element, and for example, one signal processing unit may be shared by multiple photoelectric conversion elements, and signal processing may be performed sequentially.

[0028] 2 and 3, a plurality of signal processing units 103 are arranged in a region overlapping the pixel region 12 in a plan view. A vertical scanning circuit unit 110, a horizontal scanning circuit unit 111, column circuits 112, output circuits 114, and a control pulse generating unit 115 are arranged so as to overlap between an edge of the sensor substrate 11 and an edge of the pixel region 12 in a plan view. In other words, the sensor substrate 11 has the pixel region 12 and a non-pixel region arranged around the pixel region 12, and the vertical scanning circuit unit 110, the horizontal scanning circuit unit 111, the column circuits 112, the output circuits 114, and the control pulse generating unit 115 are arranged in a region overlapping the non-pixel region in a plan view.

[0029] FIG. 4 is an example of a block diagram including the equivalent circuits of FIGS.

[0030] In FIG. 2, the photoelectric conversion element 102 having the APD 201 is provided on a sensor substrate 11, and the other members are provided on a circuit board 21.

[0031] The APD 201 is a photoelectric conversion unit that generates charge pairs in response to incident light through photoelectric conversion. A voltage VL (first voltage) is supplied to the anode of the APD 201. A voltage VH (second voltage) higher than the voltage VL supplied to the anode is supplied to the cathode of the APD 201. A reverse bias voltage is supplied to the anode and cathode so that the APD 201 performs avalanche multiplication. With such a voltage supplied, charges generated by incident light undergo avalanche multiplication, generating an avalanche current.

[0032] When a reverse bias voltage is supplied, there are two modes: Geiger mode, in which the anode and cathode are operated at a potential difference greater than the breakdown voltage, and linear mode, in which the anode and cathode are operated at a potential difference close to or less than the breakdown voltage.

[0033] 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. The APD 201 may be operated in either linear mode or Geiger mode. A SPAD is preferable because the potential difference is larger than that of a linear mode APD, resulting in a more pronounced effect in terms of withstand voltage.

[0034] The quench element 202 is connected to a power supply that supplies voltage VH and the APD 201. The quench element 202 functions as a load circuit (quench circuit) during signal multiplication by avalanche multiplication, suppressing the voltage supplied to the APD 201 and suppressing avalanche multiplication (quench operation). The quench element 202 also functions to return the voltage supplied to the APD 201 to voltage VH by passing a current equivalent to the voltage drop caused by the quench operation (recharge operation).

[0035] The signal processing unit 103 has a waveform shaping unit 210, a counter circuit 211, and a selection circuit 212. In this specification, the signal processing unit 103 may have any one of the waveform shaping unit 210, the counter circuit 211, and the selection circuit 212.

[0036] The waveform shaping unit 210 shapes the potential change at the cathode of the APD 201 obtained when photons are detected, and outputs a pulse signal. For example, an inverter circuit is used as the waveform shaping unit 210. While an example using one inverter as the waveform shaping unit 210 is shown in FIG. 4, a circuit in which multiple inverters are connected in series, or another circuit having a waveform shaping effect, may also be used.

[0037] The counter circuit 211 counts the pulse signals output from the waveform shaping unit 210 and holds the count value. When a control pulse pRES is supplied via a drive line 213, the signal held in the counter circuit 211 is reset.

[0038] A control pulse pSEL is supplied to the selection circuit 212 from the vertical scanning circuit unit 110 in Fig. 3 via a drive line 214 (not shown in Fig. 3) in Fig. 4, and switches between electrical connection and disconnection between the counter circuit 211 and the signal line 113. The selection circuit 212 includes, for example, a buffer circuit for outputting a signal.

[0039] The electrical connection may be switched by disposing a switch such as a transistor between the quench element 202 and the APD 201 or between the photoelectric conversion element 102 and the signal processing unit 103. Similarly, the supply of the voltage VH or the voltage VL to the photoelectric conversion element 102 may be electrically switched using a switch such as a transistor.

[0040] In this embodiment, a configuration using the counter circuit 211 has been described. However, instead of the counter circuit 211, the photoelectric conversion device 100 may be configured to acquire pulse detection timing using a time-to-digital converter (hereinafter referred to as TDC) and a memory. In this case, the generation timing of the pulse signal output from the waveform shaping unit 210 is converted into a digital signal by the TDC. To measure the timing of the pulse signal, a control pulse pREF (reference signal) is supplied to the TDC from the vertical scanning circuit unit 110 in FIG. 1 via a drive line. The TDC acquires, as a digital signal, a signal obtained by converting the input timing of the signal output from each pixel via the waveform shaping unit 210 into a relative time based on the control pulse pREF.

[0041] FIG. 5 is a diagram showing a schematic diagram of the relationship between the operation of an APD and an output signal.

[0042] Fig. 5(a) is a diagram illustrating the APD 201, quench element 202, and waveform shaping unit 210 of Fig. 4. Here, the input side of the waveform shaping unit 210 is referred to as node A, and the output side is referred to as node B. Fig. 5(b) shows the waveform change at node A in Fig. 5(a), and Fig. 5(c) shows the waveform change at node B in Fig. 5(a).

[0043] Between time t0 and time t1, a potential difference of VH-VL is applied to the APD 201 in FIG. 5(a). When a photon is incident on the APD 201 at time t1, avalanche multiplication occurs in the APD 201, an avalanche multiplication current flows through the quench element 202, and the voltage at node A drops. As the voltage drop increases and the potential difference applied to the APD 201 decreases, avalanche multiplication in the APD 201 stops, as shown at time t2, and the voltage level at node A drops no more than a certain value. After that, between time t2 and time t3, a current flows through node A from voltage VL to compensate for the voltage drop, and at time t3, node A settles to its original potential level. At this time, the portion of the output waveform at node A that exceeds a certain threshold is shaped by the waveform shaping unit 210 and output as a signal at node B.

[0044] The arrangement of the signal lines 113, the column circuits 112, and the output circuits 114 is not limited to that shown in Fig. 3. For example, the signal lines 113 may be arranged to extend in the row direction, and the column circuits 112 may be arranged at the ends of the signal lines 113.

[0045] The photoelectric conversion devices of the respective embodiments will be described below.

[0046] (First embodiment) The photoelectric conversion device according to the first embodiment will be described with reference to FIGS.

[0047] The circuit configuration of a pixel in a comparative example of the first photoelectric conversion device will be described using Fig. 6. Each of the first pixel 31 and the second pixel 32 shown in Fig. 6 includes an APD 301, a quench circuit 302, and a signal detection circuit 303. The first pixel 31 and the second pixel 32 also include a readout circuit 304, a signal line 305, and a control circuit 306 that are common to both the first pixel 31 and the second pixel 32.

[0048] In each pixel, the APD 301 is connected to a quench circuit 302, and an output terminal of the APD 301 is connected to a signal detection circuit 303. Detection signals based on photons photoelectrically converted by the APD 301 of the first pixel 31 and the second pixel 32 are output as pixel signals to a signal line 305 via a readout circuit 304 and a control circuit 306 that are common to the first pixel 31 and the second pixel 32. The control circuit 306 controls whether or not to output a pulse signal to the readout circuit 304, based on the output signals of the signal detection circuits 303 of the first pixel 31 and the second pixel 32. The control circuit 306 is configured by, for example, a combinational circuit or a sequential circuit.

[0049] One example of the operation of the control circuit 306 is to output a pulse signal to the readout circuit 304 when photon-based signals are detected simultaneously or closely by the first pixel 31 and the second pixel 32. This selectively reads out photon signals with high temporal and spatial correlation and filters out photon signals with weak temporal and spatial correlation. In the TOF method, signal light has strong temporal and spatial correlation, while external light and dark current, which cause spurious signals, are randomly incident and therefore have weak temporal and spatial correlation. Therefore, filtering out signals with weak temporal and spatial correlation makes it possible to efficiently distinguish between signal light and external light or dark current. However, when using the circuit configuration shown in Figure 6, the number of pixel signals output to the signal line 305 is small relative to the number of APDs 301, resulting in a problem of reduced spatial resolution.

[0050] Fig. 7 is an example of a block diagram of two pixels in the photoelectric conversion device according to this embodiment. Unlike the conventional circuit configuration shown in Fig. 6, a readout circuit 304 and a control circuit 306 are provided for each of the first pixel 31 and the second pixel 32.

[0051] In the photoelectric conversion device according to this embodiment, the control circuit 306 (first control circuit) of the first pixel 31 controls whether or not to input the output (first detection signal) of the signal detection circuit 303 (first detection circuit) of the first pixel 31 to the readout circuit 304 (first output circuit) of the first pixel 31, based on the output (second detection signal) of the signal detection circuit 303 (second detection circuit) of the second pixel 32 input via a control line 308. Furthermore, the control circuit 306 (second control circuit) of the second pixel 32 controls whether or not to input the output of the signal detection circuit 303 of the second pixel 32 to the readout circuit 304 (second output circuit) of the second pixel 32, based on the output of the signal detection circuit 303 of the first pixel 31 input via a control line 307.

[0052] An example of the operation of the control circuit 306 of the first pixel 31 is to output a pulse signal, which is a first pixel signal, to the readout circuit 304 of the first pixel 31 when the first pixel 31 and the second pixel 32 detect photons simultaneously or at close timings. Similarly, an example of the operation of the control circuit 306 of the second pixel 32 is to output a pulse signal, which is a second pixel signal, to the readout circuit 304 of the second pixel 32 when the first pixel 31 and the second pixel 32 detect photon signals simultaneously or at close timings. The control circuit 306 of the first pixel 31 may control the output of the signal based on the output of the signal detection circuit 303 of a pixel other than the second pixel 32. The control circuit 306 of the second pixel 32 may also control the output of the signal based on the output of the signal detection circuit 303 of a pixel other than the first pixel 31. The photon detection timing at which a pulse signal is output to the readout circuit 304 in each pixel will be described later.

[0053] By applying the circuit configuration shown in Figure 7, it is possible to determine the strength of the temporal and spatial correlation of the photon signal detected by the APD 301 of each pixel for each pixel, making it possible to suppress aliasing without reducing spatial resolution.

[0054] FIG. 8 shows an example of a circuit diagram for one pixel in this embodiment.

[0055] The following description will be given taking as an example the first pixel 31 of a photoelectric conversion device in which first pixels 31, second pixels 32, and third pixels 33 are arranged in a one-dimensional array. The APD 301 (first photoelectric conversion unit) of the first pixel 31 is connected to a quench circuit 302, which is a first quench element made of a P-type transistor. The quench circuit 302 is an element arranged to control the current flowing through the APD 301, and may be a resistive element, a capacitive element, or a circuit combining multiple transistors. The signal detection circuit 303 includes an inverter circuit 401 that performs waveform shaping, but may also be a resistive element, a capacitive element, or a circuit combining multiple transistors. The width td of the output pulse signal of the signal detection circuit 303 is determined according to the recovery time of the APD 301.

[0056] A pull-down circuit 405 made up of an N-type transistor is provided in the read circuit 304. The signal line 305 is reset to the “H” level via a pull-up circuit 406, and when a pulse signal is input to the pull-down circuit 405, it is switched to the “L” level.

[0057] The control circuit 306 includes a first logic circuit 402, a second logic circuit 403, and a third logic circuit 404. In FIG. 8, the first logic circuit 402, the second logic circuit 403, and the third logic circuit 404 are all NAND circuits. For example, the first logic circuit 402 performs a NAND operation on the output signal of the inverter circuit 401 of the first pixel 31 and the output signal of the inverter circuit 401 of the third pixel 33. Similarly, the second logic circuit 403 performs a NAND operation on the output signal of the inverter circuit 401 of the first pixel 31 and the output signal of the inverter circuit 401 of the second pixel 32. The third logic circuit 404 performs a NAND operation on the output signals of the first logic circuit 402 and the second logic circuit 403.

[0058] Here is an example of the operation of the control circuit 306. When the signal detection circuit 303 of the first pixel 31 outputs a high level, if at least one of the signals input from the adjacent second pixel 32 and pixel 33 is high, the control circuit 306 outputs a high level to the readout circuit 304. As a result, when the first pixel 31 detects a photon at time t0, if either the second pixel 32 or the third pixel 33 detects a photon between time t0-td and time t0+td, the signal detected by the first pixel 31 is determined to be a true signal. In other words, the period 2td, which is the period of two output pulse signals from the detection circuit 303, is considered to be the aforementioned close timing. The first pixel 31 can output a pulse signal to the readout circuit 304. The output of the signal detection circuit 303 of the first pixel 31 is connected to the control circuits 306 of the adjacent second pixel 32 and third pixel 33 via a control line 309. By arranging such pixel circuits in a chain-like array, it is possible to determine the strength of the temporal and spatial correlation of the signal based on the photons detected at each pixel for each pixel, making it possible to clearly distinguish between true and false signals.

[0059] The configuration of the control circuit 306 is not limited to that shown in Fig. 8, and any configuration that can perform a similar operation may be used. For example, the first logic circuit 402 and the second logic circuit 403 may be AND circuits, and the third logic circuit 404 may be an OR circuit.

[0060] 9 is a timing diagram showing the operation of the pixel of the photoelectric conversion device according to this embodiment. The cathode potential of the APD 301 in FIG. 8 is VC, the potential of the output terminal of the signal detection circuit 303 is V1, the potential of the control line 308 is V2, the potential of the control line 309 is V3, the potential of the output terminal of the control circuit 306 is V4, and the potential output to the signal line 305 is V5. Photon1, Photon2, and Photon3 indicate the timings at which photons are incident on the APD 301 of the first pixel 31, the second pixel 32, and the third pixel 33, respectively.

[0061] The cathode potential VC is the potential of the output terminal of the APD 301, and changes due to photoelectric conversion that occurs in accordance with the timing of Photon1 at times t1, t4, and t7.

[0062] V1 indicates a signal waveform after the change in the cathode potential VC has been waveform-shaped by the inverter circuit 401. Similarly, V2 is a pulse generated according to the timing of Photon2, and V3 is a pulse generated according to the timing of Photon3.

[0063] V4 is at the "H" level while V1 is at the "H" level and either V2 or V3 is at the "H" level. V5 is the inverted logic of V4.

[0064] Photon 1 incident on APD 301 at time t1 causes V1 to go to the “H” level during the period t1 to t2. However, V2 and V3 are at the “L” level at close timings, so V4 does not go to the “H” level and no photon detection pulse is output to V5.

[0065] Meanwhile, Photon1, which is incident at time t4, causes V1 to go to the "H" level during the period t4 to t6. The period t3 to t4 is shorter than the pulse width td, and time t3 is within the range of the period t4-td to t4+td. That is, Photon2 is incident at time t3, which is close to time t4, and V2 goes to the "H" level during the period t3 to t5, so V4 goes to the "H" level during the period t4 to t5, and a signal detection pulse is output to V5.

[0066] Similarly, Photon1, which is incident at time t7, is incident at a timing close to time t8, and since V3 becomes "H" level during the period t8 to t9, a signal detection pulse is output to V5 during the period t8 to t9. Note that Photon2 and Photon3, which are incident at time t10, cause V2 and V3 to become "H" level during the period t10 to t11, but since V1 does not become "H" level at a timing close to each other, a photon detection pulse is not output to V5 during this period.

[0067] In this embodiment, the circuit configuration is such that when adjacent pixels detect signals at close timing, the signal is regarded as a true signal, and other signals are regarded as false signals. Alternatively, a circuit configuration may be adopted in which, for example, when adjacent pixels detect signals at close timing, the signal detected first is regarded as a false signal, and the signal detected later is regarded as a true signal, thereby distinguishing between true signals and false signals in consideration of the order of detection.

[0068] FIG. 10 shows the control relationship of the pixel array of the photoelectric conversion device according to this embodiment.

[0069] When focusing on a pixel located near the center of a one-dimensional array arranged in the vertical direction, the control circuit of the pixel of interest is controlled by adjacent pixels above and below. In this embodiment, the control circuit of the pixel of interest is not controlled by pixels other than the adjacent pixels.

[0070] Furthermore, when focusing on a pixel located at the top of a one-dimensional array arranged vertically, the control circuit of the pixel of interest is controlled only by adjacent pixels below. Pixels located at the edge of the array have fewer adjacent pixels than pixels located near the center of the array. As a result, fewer pixels control the control circuit of the pixel of interest. When the control circuit of the pixel of interest is controlled by fewer pixels, the true signal cannot be detected correctly, or a false signal is more likely to be output, compared to when sufficient pixels are used to control the control pixels. Therefore, measures can be taken, such as not using the outermost pixels in subsequent image processing.

[0071] (Second embodiment) A photoelectric conversion device according to the second embodiment will be described with reference to Fig. 11 and Fig. 12. This embodiment differs from the first embodiment in the internal circuit configurations of the signal detection circuit 303 and the control circuit 306. Explanations common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described.

[0072] 11 shows an example of a circuit diagram per pixel in this embodiment. As in the first embodiment, the first pixel 31 of a photoelectric conversion device in which a first pixel 31, a second pixel 32, and a third pixel 33 are arranged in a one-dimensional array will be described as an example. An output signal from the APD 301 of the first pixel 31 is input to a first signal detection circuit 303. Furthermore, a first control circuit 306 controls whether or not the output of the first signal detection circuit 303 is input to a first readout circuit 304, depending on the outputs of the signal detection circuits 303 of the second pixel 32 and the third pixel 33.

[0073] The signal detection circuit 303 of this embodiment includes an inverter circuit 401 and a pulse shortening circuit 407. The pulse shortening circuit 407 is a circuit that generates a pulse signal having a predetermined pulse width that is shorter than the pulse width of the input signal in response to an input signal. As an example, a monostable circuit or the like is used, but other combinational circuits, sequential circuits, capacitively coupled elements, etc. may also be used. The output of the signal detection circuit 303 is divided into two systems: the output of the inverter circuit 401 is directly connected to the control line 307, and the output of the pulse shortening circuit 407 is input to the control circuit 306.

[0074] The control circuit 306 includes a logic circuit 408. The output signal of the pulse shortening circuit 407 is output to the read circuit 304 only when the signals input via the control lines 308 and 309 are both at the "L" level.

[0075] 12 is a timing diagram showing the operation of a pixel of the photoelectric conversion device according to this embodiment. The potential of the output terminal of the inverter circuit 401 in FIG. 11 is V1, and the potential of the output terminal of the pulse shortening circuit 407 is V1'. A pulse wave is generated at the cathode potential VC in response to the Photon1 signal incident on the APD 301 at times t1, t5, and t8. V1 indicates the signal waveform obtained after the change in the cathode potential VC has been waveform-shaped by the inverter circuit 401. A pulse signal obtained by shortening V1 is generated at V1'.

[0076] Photon 1 incident on APD 301 at time t1 causes V1' to go to the "H" level during the period t1 to t2. Since V2 and V3 are at the "L" level at close timing, V4 goes to the "H" level and a photon detection pulse is output to V5 during the period t1 to t2.

[0077] Photon 1, which is incident at time t5, causes V1 to go to the “H” level during the period t5 to t7. Photon 2 is incident at the adjacent time t4, and V2 goes to the “H” level before V1, so V4 goes to the “L” level and no photon detection pulse is output to V5.

[0078] Photon1 is incident at time t8, and Photon3 is incident at time t9, which is close to the incident time, causing V3 to go to the "H" level. However, since a signal based on Photon1 is detected during the period from t8 to t9 when V3 is at the "L" level, a photon detection pulse is output to V5 during the period from t8 to t9.

[0079] In this embodiment, when adjacent pixels detect signals at close timing, the circuit configuration is such that the signal detected first is considered to be the true signal and the signal detected later is considered to be the false signal, taking into account the order of detection, to distinguish between true and false signals.

[0080] In TOF ranging, in addition to the aforementioned false signals caused by external light or dark current, there are other factors that can degrade signal quality. For example, signal quality can be degraded by false signals such as crosstalk between the light source and the light receiving element caused by the reflection of emitted light inside the TOF module housing, or crosstalk between pixels caused by the avalanche emission phenomenon. Signals caused by such crosstalk components are known to have very strong temporal and spatial correlations.

[0081] In this embodiment, signals with weak temporal and spatial correlation are read as true signals, and signals with strong temporal and spatial correlation are regarded as false signals and filtered. This makes it possible to suppress false signals due to crosstalk while achieving high spatial resolution. Furthermore, the provision of a pulse shortening circuit 407 shortens the period during which photons are distinguished as closely spaced. This makes it possible to filter signals with stronger temporal correlation as false signals.

[0082] The circuit configuration and circuit operation for realizing this embodiment are not limited to the configuration described above. For example, when signals are detected at close timing, signals with strong temporal and spatial correlation may be filtered using a circuit configuration that considers them to be spurious signals regardless of the order of detection.

[0083] (Third embodiment) A photoelectric conversion device according to a third embodiment of the present invention will be described with reference to Fig. 13 to Fig. 15. The photoelectric conversion device according to this embodiment differs from the first embodiment in that pixels are arranged in a two-dimensional array. Explanations common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described.

[0084] 13 shows an example of a circuit diagram per pixel in this embodiment. An example will be described in which a first pixel 31 is surrounded by a second pixel 32 and a third pixel 33 adjacent to each other on the top and bottom, and a fourth pixel 34 and a fifth pixel 35 adjacent to each other on the left and right. In other words, the first pixel 31 and the second pixel 32 are aligned in a first direction, and the second pixel 32 and the fourth pixel 34 are aligned in a second direction intersecting the first direction. The first pixel 31 and the fifth pixel 35 are aligned in a third direction intersecting the first direction. The first pixel 31 includes an APD 301 (first photoelectric conversion unit), a signal detection circuit 303 (first detection circuit) that outputs a first detection signal, and a control circuit 306 (first control circuit). Similarly, the second pixel 32 has an APD 301 (second photoelectric conversion unit), a signal detection circuit 303 (second detection circuit) that outputs a second detection signal, and a control circuit 306 (second control circuit). The third pixel 33 has an APD 301 (third photoelectric conversion unit), a signal detection circuit 303 (third detection circuit) that outputs a third detection signal, and a control circuit 306 (third control circuit). The fourth pixel 34 has an APD 301 (fourth photoelectric conversion unit), a signal detection circuit 303 (fourth detection circuit) that outputs a fourth detection signal, and a control circuit 306 (fourth control circuit). The fifth pixel 31 has an APD 301 (fifth photoelectric conversion unit), a signal detection circuit 303 (fifth detection circuit) that outputs a fifth detection signal, and a control circuit 306 (fifth control circuit).

[0085] The control circuit 306 of the first pixel 31 controls whether or not the output signal of the signal detection circuit 303 of the first pixel 31 is input to the readout circuit 304 of the first pixel 31, depending on the output signal of the signal detection circuit 303 of each of the second to fifth pixels. The output signal of the signal detection circuit 303 of the first pixel 31 is input to the control circuits 306 of the second pixel 32, the third pixel 33, the fourth pixel 34, and the fifth pixel 35 via a control line 307.

[0086] The signal detection circuit 303 of this embodiment is configured to include an inverter circuit 501 that performs waveform shaping, and a gate circuit 502 (first selection circuit). The gate circuit 502 outputs the output signal of the inverter circuit 501 to the control circuit 306 while a gate signal VG input from outside the pixel is at the "H" level. On the other hand, while the gate signal VG is at the "L" level, the gate circuit 502 does not output the output signal of the inverter circuit 501 to the control circuit 306. By inputting a pulse of, for example, nanosecond or picosecond level as the gate signal VG, it is possible to selectively detect only photon signals that are incident during a period of interest.

[0087] The readout circuit 304 in this embodiment is configured to include a counter circuit 505 and an output circuit 506. The counter circuit 505 measures the incident intensity of photons detected by the first pixel 31 by counting the number of input pulses. An example of the counter circuit 505 is a multi-bit digital counter, but a 1-bit digital memory or an analog memory using a capacitive element may also be used. The counter circuit 505 and the output circuit 506 are connected by wiring the number of which corresponds to the number of bits of the counter circuit 505. The output circuit 506 receives a selection signal input from outside the pixel and outputs a signal output from the counter circuit 505 to the signal line 305.

[0088] The control circuit 306 in this embodiment is configured to include a logic circuit 503 and a logic circuit 504. As an example of the control circuit 306, the logic circuit 503 takes the logical sum of four signal lines 308, 309, 310, and 311, and the logic circuit 504 takes the logical product of the output of the gate circuit 502 and the output of the logic circuit 503. With this circuit configuration, a signal generated when the first pixel 31 and at least one of the second pixel 32, the third pixel 33, the fourth pixel 34, and the fifth pixel 35 detect photons at close timing can be considered as a true signal. Note that the logic circuits 503 and 504 may use NOR circuits or NAND circuits instead of OR circuits or AND circuits, or may be configured using other combinational circuits or sequential circuits.

[0089] Fig. 14 is a timing diagram showing the operation of the pixels of the photoelectric conversion device according to this embodiment. VR denotes the potential input to the quench element in Fig. 13, V0 denotes the potential of the output terminal of the inverter circuit 501, V6 denotes the potential of the output terminal of the control circuit 306, and V7 denotes the potential of the output terminal of the counter circuit 505. Photon1 to Photon5 indicate the timings at which photons are incident on the APDs 301 of the first to fifth pixels, respectively.

[0090] At time t1, VR is set to the “L” level. The unit time is the time until VR is set to the “L” level again at time t10. The potential VR is a reset signal that resets the cathode potential VC of the APD 301 by switching the resistance value of the quench element.

[0091] At time t2, VG ​​is set to the "H" level. During the period t2 to t5 when VG is at the "H" level, the output signal of the inverter circuit 501 is output to the control circuit 306. In other words, the period when VG is at the "H" level is a period when a detection signal based on photons incident on the APD 301 is detected, and the period when VG is at the "L" level is a period when the detection signal is not detected.

[0092] At time t3, Photon 1 is incident on the APD 301, and a pulse wave is generated in the cathode potential V C. As the cathode potential V C changes, the output V O of the inverter circuit 501 transitions, and V I becomes the “H” level during the period from t3 to t5.

[0093] At time t4, which is close to time t3, Photon 4 is incident on the APD 301, and V4 becomes the “H” level. Since V1 and V4 are at the “H” level from time t4 to t5, V6 becomes the “H” level, and the count value of the counter circuit 505 changes.

[0094] Photon1 is incident at time t6 and time t8, Photon2 at time t7, Photon3 at time t9, and Photon5 at time t10. Note that, since VG is at the “L” level, the output signal of the inverter circuit 501 of each pixel is not output to the control circuit 306.

[0095] FIG. 15 shows the control relationship of the pixel array of the photoelectric conversion device according to this embodiment.

[0096] When focusing on a pixel located near the center of a two-dimensional array, the control circuit of the pixel of interest is controlled by four adjacent pixels located above, below, left, and right. In this embodiment, the control circuit of the pixel of interest is not controlled by pixels other than the adjacent pixels, such as pixels located diagonally.

[0097] Furthermore, when focusing on a pixel located at the right end of a two-dimensional array, the control circuit of the pixel of interest is controlled only by three adjacent pixels: the pixels located above and below it, and the pixel adjacent to the pixel on the left side of the pixel of interest. Pixels located on the outermost periphery of the array have fewer adjacent pixels than pixels located outside the outermost periphery of the array. As a result, fewer pixels control the control circuit of the pixel of interest. When the control circuit of the pixel of interest is controlled by fewer pixels, the true signal cannot be detected correctly, or a false signal is more likely to be output, compared to when sufficient pixels are used to control the control pixels. Therefore, measures can be taken, such as not using the outermost pixels in subsequent image processing.

[0098] In this embodiment, the circuit is configured so that a signal detected at a timing close to any of four adjacent pixels is considered to be a true signal, and other signals are considered to be alias signals. Applying this embodiment to a two-dimensional array makes it possible to determine the strength of spatial correlation of signals in the X and Y directions for each pixel, thereby achieving higher accuracy in alias suppression than when using a one-dimensional array.

[0099] (Modification of the third embodiment) A modification of the third embodiment will be described with reference to FIG.

[0100] Figure 16 shows the control relationship of the pixel array in this modified example. The pixel circuit configuration and drive timing are similar to those of the third embodiment. One difference from the third embodiment is the arrangement of the pixels that control the pixel of interest. Four types of connection relationships, Pattern 1 to Pattern 4, are explained below.

[0101] In the connection relationship of pattern 1 shown in Figure 16(a), the control circuit 306 of the pixel of interest is controlled by eight pixels surrounding the pixel of interest. The eight pixels surrounding the pixel of interest are the four pixels adjacent to the pixel of interest on the top, bottom, left, and right sides, and the four pixels arranged diagonally around the pixel of interest. Because the number of pixels controlling the pixel of interest is greater than in the third embodiment, light utilization efficiency is improved, and even weaker signals can be detected with high accuracy.

[0102] In pattern 2 shown in Figure 16(b), the control circuit 306 of the pixel of interest is controlled by four pixels arranged diagonally, but not by the four nearest pixels above, below, left, and right. In pixel arrays using APDs, crosstalk caused by avalanche light emission tends to generate false signals with strong time correlation with the nearest pixels. By adopting the control relationship shown in Figure 16(b), it is possible to accurately detect signals with strong temporal and spatial correlation while suppressing the effects of crosstalk components.

[0103] 16(c), the control circuit 306 of the pixel of interest is controlled by 12 pixels, including a pixel that is not directly adjacent to the pixel of interest and is two pixels away from the pixel of interest. By adopting such a control relationship, it becomes possible to accurately detect signals with strong time correlation even when the spatial correlation of signals is reduced due to blurring caused by the optical lens or subject motion.

[0104] In pattern 4 shown in FIG. 16(d), the pixels controlling the control circuit 306 of the pixel of interest are arranged offset in the X and Y directions. Specifically, the control circuit 306 of the pixel of interest is controlled by three pixels: the pixels adjacent to the pixel of interest below and to the left, and the pixel arranged below and to the left of the pixel of interest. This control relationship enables accurate discrimination between true and false signals even when the spatial correlation of the signal to be detected is asymmetric due to the characteristics or constraints of the optical system or the subject. Note that when the pattern shown in FIG. 16(d) is applied to a two-dimensional pixel array, the "group of pixels controlling the pixel of interest" and the "group of pixels controlled by the pixel of interest" do not necessarily coincide. In other words, the number of pixels controlling the pixel of interest and the number of pixels controlled by the pixel of interest do not necessarily have to be the same. However, the effects of this embodiment can be obtained in the same way as with the patterns shown in FIGS. 15 and 16(a) to 16(c).

[0105] (Fourth embodiment) A fourth embodiment of the present invention will be described with reference to FIGS.

[0106] 17 shows an example of a circuit diagram per pixel of this embodiment. This embodiment differs from the third embodiment in the circuit configuration inside the control circuit 306. Explanations common to the first to third embodiments will be omitted, and differences from the third embodiment will be mainly described.

[0107] The control circuit 306 in this embodiment is configured to include a multiplexer circuit 508 and a logic circuit 509 .

[0108] The multiplexer circuit 508 can switch the function of the control circuit 306 between Enable and Disable in accordance with a signal S input from outside the pixel. When the function of the control circuit 306 is enabled, the control circuit 306 of the first pixel 31 controls whether or not to output the output of the signal detection circuit 303 of the first pixel 31 to the readout circuit 304 of the first pixel 31 in accordance with signals from the second to fifth adjacent pixels. When the function of the control circuit 306 is disabled, the output of the signal detection circuit 303 of the first pixel 31 is directly output to the readout circuit 304 of the first pixel 31, regardless of the outputs of the adjacent pixels.

[0109] As an example of the logic circuit 509, similar to the third embodiment, a circuit configuration is possible in which the logic circuit 509 first calculates the logical sum of the outputs of the signal detection circuits 303 of adjacent pixels, and then calculates the logical product of the output of the logical sum and the output of the signal detection circuit 303 of the first pixel 31. The logic circuit 509 may be configured to output the output of the signal detection circuit 303 of the first pixel 31 to the readout circuit 304 of the first pixel 31 only when the outputs of the signal detection circuits 303 of N or more adjacent pixels (N is an integer of 2 or greater) are at the “H” level. The logic circuit 509 may be configured to output an “H” level to the readout circuit 304 of the first pixel 31 only when the outputs of the signal detection circuits 303 of the first pixel 31 and N or more adjacent pixels (N is an integer of 2 or greater) to the first pixel 31 are at the “H” level. Furthermore, a configuration is also possible in which the output of the signal detection circuit 303 is weighted depending on the arrangement of adjacent pixels involved in the control of the control circuit 306. For example, a circuit configuration may be adopted in which the output of the signal detection circuit 303 of the first pixel 31 is output to the readout circuit 304 of the first pixel 31 only when the weighted sum of signals that becomes the "H" level exceeds a certain threshold value M. Each of the threshold values ​​N and M may be a predetermined value, or may be a variable that can be rewritten from outside the pixel.

[0110] Furthermore, the signal detection circuit 303 of this embodiment is configured to include an inverter circuit 501, a gate circuit 502, and a latch circuit 507 (first latch circuit). The latch circuit 507 latches to the "H" level when it detects a photon during the period when the gate signal VG is at the "H" level. Next, when the recharge signal VR becomes the "L" level, the latch circuit 507 is also reset to the "L" level. In this way, by holding a signal based on photon detection in the latch circuit 507, it is possible to accurately distinguish between true and false signals even when timing variations occur in the circuits of the first pixel 31 and adjacent pixels.

[0111] 18A and 18B are timing diagrams showing the operation of the pixel of the photoelectric conversion device according to this embodiment, in which Fig. 18A shows the timing diagram of the first driving mode in which the control circuit is enabled, and Fig. 18B shows the timing diagram of the second driving mode in which the control circuit is disabled.

[0112] 18(a), VR is set to the "L" level at time t1, and the time until VR is set to the "L" level again at time t10 is defined as the unit time.

[0113] At time t2, VG ​​is set to the “H” level. During the period t2 to t5 when VG is at the “H” level, the output signal of the inverter circuit 501 is output to the control circuit 306.

[0114] At time t3, Photon 1 is incident on the APD 301, and a pulse wave is generated in the cathode potential V C. As the cathode potential V C changes, the output V O of the inverter circuit 501 transitions, and V I becomes the “H” level during the period from t3 to t5.

[0115] At time t4, which is close to time t3, Photon 4 is incident on APD 301, and V4 goes to the “H” level. Because V1 and V4 are at the “H” level from time t4 to t5, V6 goes to the “H” level, and a photon detection pulse is output to V5 during the period from t1 to t2.

[0116] Photon1 is incident at time t6 and time t8, Photon2 at time t7, Photon3 at time t9, and Photon5 at time t10. Note that since VG is at the “L” level, the output signal of the inverter circuit 501 is not output to the control circuit 306.

[0117] 18(b), VR is set to the "L" level at time t1, as in FIG. 18(a). The unit time is the time until VR is set to the "L" level again at time t10.

[0118] At time t2, VG ​​is set to the “H” level. During the period t2 to t5 when VG is at the “H” level, the output signal of the inverter circuit 501 is output to the control circuit 306.

[0119] At time t3, Photon 1 is incident on the APD 301, generating a pulse wave at the cathode potential V C. As the cathode potential V C changes, the output V O of the inverter circuit 501 transitions, and when V I goes to the “H” level, V C also goes to the “H” level, and a photon detection pulse is output to V C during the period from t3 to t5.

[0120] Photon1 is incident at times t6 and t8, Photon4 at t4, Photon2 at time t7, Photon3 at time t9, and Photon5 at time t10, but these signals do not contribute to the change in V6. Note that, since VG is at the "L" level, the output signal of the inverter circuit 501 is not output to the control circuit 306.

[0121] In the second embodiment, when adjacent pixels detect signals at close timing, the signal detected first is regarded as a true signal and the signal detected later is regarded as a false signal, thereby filtering out signals due to crosstalk components. In contrast, in the present embodiment, when adjacent pixels detect signals at close timing, the signal detected earlier is regarded as a false signal and the signal detected later is regarded as a true signal, thereby filtering out signals due to external light components.

[0122] In this embodiment, it is possible to switch between a drive mode that distinguishes between true and false signals based on the strength of temporal and spatial correlation, and a drive mode that outputs a signal regardless of the strength of temporal and spatial correlation. By selecting the optimal drive mode depending on the scene, it is possible to improve the signal quality during shooting.

[0123] (Fifth embodiment) A photoelectric conversion device according to the fifth embodiment will be described with reference to Fig. 19. Fig. 19 is a diagram showing the control relationship of the pixel array of the photoelectric conversion device according to this embodiment. In the photoelectric conversion device according to this embodiment, pixels having different connection relationships with pixels related to the control of the control circuit are mixed.

[0124] As shown in Fig. 19(a), pixels A and B are arranged in a two-dimensional array. Pixels A and B have different connection relationships with the pixels involved in the control of the control circuit. In Fig. 19(a), pixel rows in which pixels A are arranged and pixel rows in which pixels B are arranged are arranged alternately every other row.

[0125] Figure 19(b) shows the control relationship for pixel A, and Figure 19(c) shows the control relationship for pixel B. The control circuit for pixel A is controlled by the two pixels adjacent to the left and right of the pixel of interest. On the other hand, the control circuit for pixel B is controlled by the pixels in one row in the row in which the pixel of interest is arranged. In an arrangement in which pixel rows in which pixels A are arranged and pixel rows in which pixels B are arranged alternately as shown in Figure 19(a), pixels A are connected to each other, and pixels B are connected to each other.

[0126] The number and location of pixels involved in the control differ between pixel A and pixel B, and therefore the strength of the spatial correlation of the detected signals also differs. With this type of photoelectric conversion device, signals with strong and weak spatial correlation can be acquired simultaneously, which has the effect of improving the accuracy of distinguishing between true signals and false signals.

[0127] (Modification of the fifth embodiment) A modification of the fifth embodiment will be described with reference to FIG.

[0128] The control relationship of the pixel array in this modification is shown in Figure 20. This modification has in common with the fifth embodiment that pixels having different connection relationships with pixels involved in the control of the control circuit are mixed together, but differs from the fifth embodiment in that pixels having different connection relationships are connected to each other.

[0129] As shown in Fig. 20(a), pixels A and B are arranged in a two-dimensional array. Pixels A and B differ in the connection relationship with the pixels involved in the control of the control circuit. In Fig. 20(a), pixels A and B are arranged alternately.

[0130] Figure 20(b) shows the control relationship for pixel A, and Figure 20(c) shows the control relationship for pixel B. The control circuit for pixel A is controlled by four pixels adjacent to the pixel of interest on all four sides. On the other hand, the control circuit for pixel B is controlled by a total of eight pixels: four pixels diagonally opposite the pixel of interest and four pixels two pixels away from the pixel of interest. In an arrangement in which pixels A and B are alternately arranged as shown in Figure 20(a), pixels A and B are connected to each other for control by their control circuits.

[0131] The number and location of pixels involved in the control differ between pixel A and pixel B, and therefore the strength of the spatial correlation of the detected signals also differs. With this type of photoelectric conversion device, signals with strong and weak spatial correlation can be acquired simultaneously, which has the effect of improving the accuracy of distinguishing between true signals and false signals.

[0132] (Sixth embodiment) The photoelectric conversion system according to this embodiment will be described with reference to Fig. 21. Fig. 21 is a block diagram showing a schematic configuration of the photoelectric conversion system according to this embodiment.

[0133] The photoelectric conversion devices described in the first to sixth embodiments 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. Also included in the photoelectric conversion system is a camera module equipped with an optical system such as a lens and an imaging device. Fig. 21 illustrates a block diagram of a digital still camera as an example of such systems.

[0134] 21 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 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.

[0135] The photoelectric conversion system also includes a signal processing unit 1007, which is an image generation unit that generates an image by processing an output signal output from the 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 on the same semiconductor substrate on which the imaging device 1004 is provided, or may be formed on a semiconductor substrate separate from the imaging device 1004.

[0136] 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 imaging 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.

[0137] The photoelectric conversion system further includes an overall control and 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.

[0138] The imaging device 1004 outputs an imaging signal to a 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.

[0139] As described above, according to this embodiment, it is possible to realize a photoelectric conversion system to which the photoelectric conversion device (imaging device) according to any one of the above embodiments is applied.

[0140] (Seventh embodiment) The photoelectric conversion system and the moving object of this embodiment will be described with reference to Fig. 22. Fig. 22 is a diagram showing the configuration of the photoelectric conversion system and the moving object of this embodiment.

[0141] FIG. 22(a) shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 1300 includes an image capture device 1310. The image capture device 1310 is the photoelectric conversion device described in any of the above embodiments. The photoelectric conversion system 1300 includes an image processing unit 1312 that performs image processing on multiple pieces of image data acquired by the image capture device 1310, and a parallax acquisition unit 1314 that calculates parallax (phase difference between parallax images) from the multiple pieces of image data acquired by the photoelectric conversion system 1300. The photoelectric conversion system 1300 also includes a distance acquisition unit 1316 that calculates the distance to an object based on the calculated parallax, and a collision determination unit 1318 that determines whether or not there is a possibility of a collision based on the calculated distance. Here, the parallax acquisition unit 1314 and the distance acquisition unit 1316 are examples of distance information acquisition means that acquire distance information to the object. In other words, the distance information is information related to the parallax, the defocus amount, the distance to the object, etc. The collision determination unit 1318 may determine the possibility of a collision using any of these distance information. The distance information acquisition means may be realized by dedicated hardware, a software module, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or a combination thereof.

[0142] The photoelectric conversion system 1300 is connected to a vehicle information acquisition device 1320 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The photoelectric conversion system 1300 is also connected to a control ECU 1330, which is a 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 1318. The photoelectric conversion system 1300 is also connected to an alarm device 1340 that issues an alarm to the driver based on the determination result of the collision determination unit 1318. For example, if the determination result of the collision determination unit 1318 indicates a high possibility of a collision, the control ECU 1330 performs vehicle control to avoid the collision and mitigate damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 1340 warns the user by sounding an alarm, displaying alarm information on a screen of a car navigation system, etc., or vibrating the seat belt or steering wheel.

[0143] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are imaged by the photoelectric conversion system 1300. Fig. 22(b) shows the photoelectric conversion system when imaging the area in front of the vehicle (imaging range 1350). A vehicle information acquisition device 1320 sends instructions to the photoelectric conversion system 1300 or the imaging device 1310. This configuration can further improve the accuracy of distance measurement.

[0144] 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, and control of automatic driving to prevent deviation from a lane. 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).

[0145] (Eighth embodiment) The photoelectric conversion system of this embodiment will be described with reference to Fig. 23. Fig. 23 is a block diagram showing an example of the configuration of a range image sensor which is the photoelectric conversion system of this embodiment.

[0146] 23, the range image sensor 401 is configured to include an optical system 407, a photoelectric conversion device 408, an image processing circuit 404, a monitor 405, and a memory 406. The range image sensor 401 can obtain a range image according to the distance to the subject by receiving light (modulated light or pulsed light) that is projected toward the subject from a light source device 409 and reflected from the surface of the subject.

[0147] The optical system 407 is configured to have one or more lenses, and guides image light (incident light) from a subject to the photoelectric conversion device 408, forming an image on the light receiving surface (sensor section) of the photoelectric conversion device 408.

[0148] The photoelectric conversion device 408 is the photoelectric conversion device of each of the above-described embodiments, and a distance signal indicating a distance determined from a light reception signal output from the photoelectric conversion device 408 is supplied to the image processing circuit 404.

[0149] The image processing circuit 404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 408. The distance image (image data) obtained by this image processing is then supplied to a monitor 405 for display, or supplied to a memory 406 for storage (recording).

[0150] In the range image sensor 401 configured in this way, by applying the above-described photoelectric conversion device, it is possible to obtain, for example, a more accurate range image as the pixel characteristics improve.

[0151] (Ninth embodiment) The photoelectric conversion system of this embodiment will be described with reference to Fig. 24. Fig. 24 is a diagram showing an example of a schematic configuration of an endoscopic surgery system, which is the photoelectric conversion system of this embodiment.

[0152] 24 shows a state in which an operator (doctor) 1131 is performing surgery on a patient 1132 on a patient bed 1133 using an endoscopic surgery system 1150. As shown in the figure, the endoscopic surgery system 1150 is composed of an endoscope 1100, a surgical tool 1110, and a cart 1134 on which various devices for endoscopic surgery are mounted.

[0153] 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 example shown, 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.

[0154] 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 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. The endoscope 1100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0155] 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 sent to a camera control unit (CCU) 1135 as RAW data.

[0156] The CCU 1135 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of 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.

[0157] 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 .

[0158] 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.

[0159] The input device 1137 is an input interface for the endoscopic surgery system 1150. A user can input various information and instructions to the endoscopic surgery system 1150 via the input device 1137.

[0160] 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.

[0161] 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 configured from, for example, 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, making it possible to adjust the white balance of the captured image in the light source device 1203. In this case, it is also possible to capture images corresponding to each RGB color in a time-division manner 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. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0162] 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 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 of so-called blocked-up shadows and blown-out highlights.

[0163] The light source device 1203 may also be configured to supply light in a predetermined wavelength band corresponding to special light observation. Special light observation utilizes, for example, the wavelength dependency of light absorption in body tissue. Specifically, specific tissue, such as blood vessels on the surface of the mucous membrane, can be photographed with high contrast by irradiating light with a narrower band than the light (i.e., white light) used in normal observation. 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 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 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0164] (Tenth embodiment) The photoelectric conversion system of this embodiment will be described with reference to FIGS. 25(a) and (b). FIG. 25(a) illustrates glasses 1600 (smart glasses) which are the photoelectric conversion system of this embodiment. The glasses 1600 have a photoelectric conversion device 1602. The photoelectric conversion device 1602 is the photoelectric conversion device described in each of the above embodiments. 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. 25(a).

[0165] 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.

[0166] FIG. 25(b) illustrates glasses 1610 (smart glasses) according to one application example. The glasses 1610 include a control device 1612, which includes 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 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.

[0167] 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 an image of the eyeball. One example is a gaze detection method based on the Purkinje image formed by reflection of irradiated light on the cornea.

[0168] 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.

[0169] 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 about the user's line of sight from the photoelectric conversion device.

[0170] 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.

[0171] 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 and second field-of-view areas 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.

[0172] Note that AI may be used to determine the first field of view area and areas 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 an 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 an external device, it is transmitted to the display device via communication.

[0173] 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.

[0174] [Modified embodiment] The present invention is not limited to the above-described embodiment, and various modifications are possible.

[0175] For example, an example in which part of the configuration of any one of the embodiments is added to another embodiment, or an example in which part of the configuration of another embodiment is replaced with another embodiment, is also included in the embodiments of the present invention.

[0176] Furthermore, the photoelectric conversion systems shown in the sixth and seventh embodiments are examples of photoelectric conversion systems to which a photoelectric conversion device can be applied, and photoelectric conversion systems to which the photoelectric conversion device of the present invention can be applied are not limited to the configurations shown in Figures 21 and 22. The same applies to the ToF system shown in the eighth embodiment, the endoscope shown in the ninth embodiment, and the smart glasses shown in the tenth embodiment.

[0177] 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]

[0178] 301 Photoelectric conversion unit 303 Detection Circuit 304 Output circuit 306 Control Circuit

Claims

1. a first photoelectric conversion unit; a first detection circuit that outputs a first detection signal based on photons incident on the first photoelectric conversion unit; a first output circuit that outputs a first pixel signal to an outside of the pixel in response to the first detection signal; a first pixel including a first control circuit that controls whether or not the first detection signal is input to the first output circuit; a second photoelectric conversion unit; a second detection circuit that outputs a second detection signal based on photons incident on the second photoelectric conversion unit; a second output circuit that outputs a second pixel signal to an outside of the pixel in response to the second detection signal; a second control circuit that controls whether or not the second detection signal is input to the second output circuit; and a pixel region in which a plurality of pixels including the second pixel are arranged in an array; The photoelectric conversion device according to claim 1, wherein the first control circuit controls whether or not the first detection signal is input to the first output circuit in response to the second detection signal.

2. 2. The photoelectric conversion device according to claim 1, wherein the first photoelectric conversion unit and the second photoelectric conversion unit are avalanche photodiodes.

3. 3. The photoelectric conversion device according to claim 1, wherein the first output circuit has a memory for storing the first detection signal or a counter circuit for counting the first detection signal.

4. 4. The photoelectric conversion device according to claim 1, wherein the first control circuit is a logic circuit that performs a logical AND operation on the first detection signal and the second detection signal.

5. 5. The photoelectric conversion device according to claim 1, wherein the second control circuit determines whether or not to input the second detection signal to the second output circuit in accordance with the first detection signal.

6. a third photoelectric conversion unit; a third detection circuit that outputs a third detection signal based on photons incident on the third photoelectric conversion unit; a third output circuit that outputs a third pixel signal to an outside of the pixel in response to the third detection signal; a third control circuit that controls whether or not the third detection signal is input to the third output circuit; 6. The photoelectric conversion device according to claim 1, wherein the third control circuit determines whether or not to output the third detection signal to the third output circuit in response to the second detection signal.

7. the first pixel and the second pixel are aligned in a first direction, 7. The photoelectric conversion device according to claim 6, wherein the second pixel and the third pixel are aligned in a second direction that intersects with the first direction.

8. 8. The photoelectric conversion device according to claim 6, wherein the first control circuit determines whether or not to output the first detection signal to the first output circuit in response to the third detection signal.

9. a fourth photoelectric conversion unit; a fourth detection circuit that outputs a fourth detection signal based on photons incident on the fourth photoelectric conversion unit; a fourth output circuit that outputs a fourth pixel signal to an outside of the pixel in response to the fourth detection signal; a fourth control circuit that controls whether or not the fourth detection signal is input to the fourth output circuit; 7. The photoelectric conversion device according to claim 1, wherein the first control circuit determines whether or not to output the first detection signal to the first output circuit depending on the second detection signal and the fourth detection signal.

10. the first pixel and the second pixel are aligned in a first direction, 10. The photoelectric conversion device according to claim 9, wherein the second pixel and the fourth pixel are aligned in a third direction that intersects with the first direction.

11. 11. The photoelectric conversion device according to claim 1, wherein, of the plurality of pixels included in the pixel region, the second pixel is not the pixel closest to the first pixel.

12. 12. The photoelectric conversion device according to claim 1, wherein the first detection circuit has a first selection circuit that selects a detection period in which the first detection signal is detected and a non-detection period in which the first detection signal is not detected.

13. the first pixel has a first quenching element; the first detection circuit includes a first latch circuit; 13. The photoelectric conversion device according to claim 1, wherein the first latch circuit and the first quench element are controlled by a common reset signal.

14. 14. The photoelectric conversion device according to claim 1, wherein the first detection circuit includes a monostable circuit that outputs the first detection signal having a pulse width shorter than a pulse width of an input signal to the first detection circuit.

15. the number of pixels that output detection signals that control the first control circuit; 15. The photoelectric conversion device according to claim 1, wherein the number of pixels including output circuits controlled by the first control circuit is equal to the number of pixels including output circuits controlled by the first control circuit.

16. The number of detection signals that control the control circuits of the pixels arranged on the outermost periphery of the pixel region is 15. The photoelectric conversion device according to claim 1, wherein the number of detection signals that control control circuits of pixels arranged other than the outermost periphery of the pixel region is smaller than the number of detection signals that control control circuits of pixels arranged other than the outermost periphery of the pixel region.

17. 17. The photoelectric conversion device according to claim 1, wherein the first detection signal is input to the first output circuit when a photon is detected at the first pixel before a photon is detected at the second pixel within a unit time.

18. 17. The photoelectric conversion device according to claim 1, wherein the first detection signal is input to the first output circuit when a photon is detected at the second pixel before a photon is detected at the first pixel within a unit time.

19. a first driving mode that determines whether or not to input the first detection signal to the first control circuit in response to the second detection signal; 19. The photoelectric conversion device according to claim 1, further comprising: a second driving mode in which the first detection signal is input to the first control circuit regardless of the second detection signal.

20. a sensor substrate on which the first photoelectric conversion unit is disposed; 20. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion device is a stacked sensor in which a circuit board on which the first output circuit is arranged is stacked.

21. 21. The photoelectric conversion device according to claim 20, wherein the first control circuit is disposed on the circuit board.

22. A photoelectric conversion system including a plurality of photoelectric conversion devices according to any one of claims 1 to 21, a light emitting unit that emits light to be detected by the photoelectric conversion device; and a calculation means for calculating a distance using the digital signal held in the photoelectric conversion device.

23. A mobile object, The photoelectric conversion device according to any one of claims 1 to 21, a distance information acquisition means for acquiring distance information to an object from a parallax image based on a signal from the photoelectric conversion device; and a control means for controlling the moving body based on the distance information.

Images