Photoelectric conversion device and optical detection system

Abstract

To provide a photoelectric conversion device and an optical detection system that can improve a reading speed without reducing the accuracy of outputting signals.SOLUTION: A photoelectric conversion device is provided, which comprises: a plurality of pixels each having a photoelectric conversion unit that outputs a photon detection signal according to incident of photons, a counting unit that holds a count value obtained by counting the photon detection signals with a predetermined number of bits, and a switching unit that switches information output from the counting unit between first information including information on upper bits, of the predetermined number of bits held by the counting unit, and second information including the information on the upper bits and information on the other bits; and a detection unit that extracts, from the plurality of pixels on the basis of the first information, detection pixels that are pixels to output the second information.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion device and a light detection system.

Background Art

[0002] In recent years, a photon counting type image sensor that counts the number of photons incident on a photodiode during an exposure period and outputs the counted value as a signal value has been proposed. Patent Document 1 discloses an imaging device using an APD (avalanche photodiode). This imaging device reads only the signals of pixels whose difference between the previous frame and the current frame exceeds a threshold value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, although the imaging device described in Patent Document 1 can improve the readout speed, there is a problem that the output accuracy of the signal decreases because the signals in the regions where reading is not performed are missing.

[0005] Therefore, an object of the present invention is to provide a photoelectric conversion device and a light detection system capable of improving the readout speed without reducing the output accuracy of the signal.

Means for Solving the Problems

[0006] According to one disclosure of the present specification, a photoelectric conversion unit that outputs a photodetector signal in response to the incidence of photons, a counting unit that holds a count value obtained by counting the photodetector signal with a predetermined number of bits, and information output from the counting unit are provided. A plurality of pixels each having a switching unit that switches between first information including information of upper bits and second information including information of the upper bits and information of other bits among the predetermined number of bits held by the counting unit, and based on the first information. And a detection unit that extracts a detection pixel that is a pixel to be output of the second information from among the plurality of pixels. A photoelectric conversion device is provided.

Effect of the Invention

[0007] According to the present invention, it is possible to realize a photoelectric conversion device and a light detection system capable of improving the reading speed without reducing the output accuracy of a signal.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Embodiments for Carrying Out the Invention

[0009] The embodiments shown below are for embodying the technical idea of the present invention and do not limit the present invention. The sizes and positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation. In the following description, the same configurations may be denoted by the same reference numerals and the description thereof may be omitted.

[0010] [First Embodiment] The schematic configuration and basic operation of the photoelectric conversion device according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is a perspective view showing a configuration example of the photoelectric conversion device according to the present embodiment. FIG. 2 is a plan view showing the schematic configuration of the sensor substrate of the photoelectric conversion device according to the present embodiment. FIG. 3 is a block diagram showing a configuration example of a pixel of the photoelectric conversion device according to the present embodiment. FIG. 4 is a block diagram showing a configuration example of a pixel of the photoelectric conversion device according to the present embodiment. FIG. 5 is a diagram for explaining the basic operation of the photoelectric conversion unit of the photoelectric conversion device according to the present embodiment.

[0011] The photoelectric conversion device 100 according to the present embodiment has, as shown in FIGS. 1 to 3, a pixel region 10, a vertical scanning circuit unit 40, a readout circuit unit 50, a horizontal scanning circuit unit 60, an output circuit unit 70, and a control unit 80.

[0012] The pixel region 10 is provided with a plurality of pixels 12 arranged in an array so as to form a plurality of rows and a plurality of columns. Each pixel 12 can be composed of a photoelectric conversion unit including a photoelectric conversion element and a pixel signal processing unit that processes a signal output from the photoelectric conversion unit, as will be described later. Note that the number of pixels 12 constituting the pixel region 10 is not particularly limited. For example, the pixel region 10 can be composed of a plurality of pixels 12 arranged in an array of several thousand rows by several thousand columns like a general digital camera. Alternatively, the pixel region 10 may be composed of a plurality of pixels 12 arranged in one row or one column. Alternatively, the pixel region 10 may be composed of one pixel 12.

[0013] In each row of the pixel array of the pixel region 10, a control line 14 is arranged to extend in a first direction (the horizontal direction in FIG. 1). The control line 14 is connected to each of the pixels 12 arranged in the first direction and forms a common signal line for these pixels 12. The first direction in which the control line 14 extends may be referred to as the row direction or the horizontal direction. Each of the control lines 14 may include a plurality of signal lines for supplying a plurality of types of control signals to the pixels 12. The control lines 14 in each row are connected to the vertical scanning circuit unit 40.

[0014] In each column of the pixel array of the pixel region 10, a data line 16 is arranged to extend in a second direction (the vertical direction in FIG. 1) intersecting the first direction. The data line 16 is connected to each of the pixels 12 arranged in the second direction and forms a common signal line for these pixels 12. The second direction in which the data line 16 extends may be referred to as the column direction or the vertical direction. Each of the data lines 16 may include a plurality of signal lines for transferring a plurality of bits of digital signals output from the pixels 12 bit by bit. The data lines 16 in each column are connected to the readout circuit unit 50.

[0015] The vertical scanning circuit section 40 is a control section that receives a control signal output from the control section 80, generates a control signal for driving the pixel 12, and supplies it to the pixel 12 via the control line 14. Logic circuits such as a shift register and an address decoder can be used for the vertical scanning circuit section 40. The vertical scanning circuit section 40 sequentially scans the pixels 12 in the pixel region 10 row by row, and causes the pixel signals of each pixel 12 to be sequentially output to the readout circuit section 50 via the data line 16.

[0016] The readout circuit section 50 includes a plurality of holding sections (not shown) provided corresponding to each column of the pixel array in the pixel region 10, and has a function of holding the pixel signals of each column of pixels 12 output row by row from the pixel region 10 via the data line 16 in the corresponding column's holding section. The readout circuit section 50 outputs pixel signals to the output circuit section 70 and a detection section 81 described later.

[0017] The horizontal scanning circuit section 60 is a control section that receives a control signal output from the control section 80, generates a control signal for reading out pixel signals from the holding sections of each column of the readout circuit section 50, and supplies it to the readout circuit section 50. Logic circuits such as a shift register and an address decoder can be used for the horizontal scanning circuit section 60. The horizontal scanning circuit section 60 sequentially scans the holding sections of each column of the readout circuit section 50, and causes the pixel signals held in each to be sequentially output to the output circuit section 70 or the detection section 81.

[0018] The output circuit section 70 has an external interface circuit, and is a circuit section for outputting the pixel signal output from the readout circuit section 50 to the outside of the photoelectric conversion device 100. The external interface circuit included in the output circuit section 70 is not particularly limited. A SerDes (SERializer / DESerializer) transmission circuit can be applied to the external interface circuit. The SerDes transmission circuit is, for example, an LVDS (Low Voltage Differential Signaling) circuit, an SLVS (Scalable Low Voltage Signaling) circuit, or the like.

[0019] The control unit 80 is a control circuit that generates control signals for controlling the operations and their timings of the vertical scanning circuit unit 40, the readout circuit unit 50, and the horizontal scanning circuit unit 60, and supplies them to each functional block. Note that at least a part of the control signals for controlling the operations and their timings of the vertical scanning circuit unit 40, the readout circuit unit 50, and the horizontal scanning circuit unit 60 may be supplied from outside the photoelectric conversion device 100. The control unit 80 is composed of various electronic components such as a CPU and a memory, and includes a detection unit 81 and a region control unit 82.

[0020] The detection unit 81 has a function of detecting, based on the pixel signals output from the plurality of pixels 12, the pixels 12 that are to be the targets for outputting pixel signals to the readout circuit unit 50 among the plurality of pixels 12. The detection unit 81 outputs detection information representing the detected pixels 12 to the region control unit 82.

[0021] The region control unit 82 has a function of controlling, based on the detection information output from the detection unit 81, the region in the pixel region 10 that outputs pixel signals to the readout circuit unit 50. The region control unit 82 outputs a control signal indicating the region that is the target for outputting pixel signals in the pixel region 10 to the vertical scanning circuit unit 40 and the horizontal scanning circuit unit 60.

[0022] Each pixel 12 can be composed of, for example, a photoelectric conversion unit 20 and a pixel signal processing unit 30 as shown in FIG. 4. The photoelectric conversion unit 20 has a function of outputting a photon detection signal in response to the incidence of photons, and can be composed of, for example, a photoelectric conversion element 22 and a quench element 24. The pixel signal processing unit 30 can be composed of, for example, a waveform shaping unit 32, a counter circuit 34 as a counting unit, and a selection circuit 36 as a switching unit.

[0023] The photoelectric conversion element 22 can be an avalanche photodiode (hereinafter referred to as "APD"). The anode of the APD constituting the photoelectric conversion element 22 is connected to the node to which the voltage VL is supplied. The cathode of the APD constituting the photoelectric conversion element 22 is connected to one terminal of the quench element 24. The connection node between the photoelectric conversion element 22 and the quench element 24 is the output node of the photoelectric conversion unit 20. The other terminal of the quench element 24 is connected to the node to which a voltage VH higher than the voltage VL is supplied. The voltage VL and the voltage VH are set so that a reverse bias voltage sufficient for the APD to perform an avalanche multiplication operation is applied. In one example, a negative high voltage is given as the voltage VL, and a positive voltage of about the power supply voltage is given as the voltage VH. In one example, the voltage VL can be -30V and the voltage VH can be 3V, but from the viewpoints of improving element characteristics and suppressing deterioration, it is desirable to reduce the low voltage of the drive voltage of the APD.

[0024] The photoelectric conversion element 22 can be constituted by an APD as described above. By supplying a reverse bias voltage sufficient for the avalanche multiplication operation to the APD, the charges generated by the light incident on the APD cause avalanche multiplication, and an avalanche current is generated. The operation modes in the state where a reverse bias voltage is supplied to the APD include a Geiger mode and a linear mode. The Geiger mode is an operation mode in which the voltage applied between the anode and the cathode is a reverse bias voltage larger than the breakdown voltage of the APD. The linear mode is an operation mode in which the voltage applied between the anode and the cathode is a reverse bias voltage near or below the breakdown voltage of the APD. The APD operated in the Geiger mode is called a SPAD (Single Photon Avalanche Diode). The APD constituting the photoelectric conversion element 22 may be operated in the linear mode or may be operated in the Geiger mode.

[0025] In this embodiment, the anode of the APD is set to a fixed potential, and the signal is extracted from the cathode side. That is, the first conductive type semiconductor region having charges of the same polarity as the signal charges as majority carriers is an N-type semiconductor region, and the second conductive type semiconductor region having charges of a polarity different from the signal charges as majority carriers is a P-type semiconductor region. Also, the first conductive type carriers are electrons, and the second conductive type carriers are holes. Also, the first conductive type impurity is a donor impurity, and the second conductive type impurity is an acceptor impurity. Hereinafter, the case where one node of the APD is set to a fixed potential will be described, but the potentials of both nodes may vary.

[0026] Conversely, it is also possible to configure the cathode of the APD to be at a fixed potential and extract the signal from the anode side. In this case, the first conductive type semiconductor region having charges of the same polarity as the signal charges as majority carriers is a P-type semiconductor region, and the second conductive type semiconductor region having charges of a polarity different from the signal charges as majority carriers is an N-type semiconductor region. Also, the first conductive type carriers are holes, and the second conductive type carriers are electrons. Also, the first conductive type impurity is an acceptor impurity, and the second conductive type impurity is a donor impurity. In the case of a configuration for detecting holes as signal charges, the conductivity types of the respective semiconductor regions described later will be the reverse conductivity types.

[0027] The quench element 24 has a function of converting a change in the avalanche current generated in the photoelectric conversion element 22 into a voltage signal. Also, the quench element 24 functions as a load circuit (quench circuit) during signal multiplication by avalanche multiplication, and has a function of reducing the voltage applied to the photoelectric conversion element 22 to suppress avalanche multiplication. The operation in which the quench element 24 suppresses avalanche multiplication is called a quench operation. Also, the quench element 24 has a function of returning the voltage supplied to the photoelectric conversion element 22 to the voltage VH by flowing a current corresponding to the voltage drop caused by the quench operation. The operation in which the quench element 24 returns the voltage supplied to the photoelectric conversion element 22 to the voltage VH is called a recharge operation. The quench element 24 can be constituted by a resistance element, a MOS transistor, or the like.

[0028] The waveform shaping unit 32 has an input node to which the output signal of the photoelectric conversion unit 20 is input and an output node. The waveform shaping unit 32 has a function of converting the analog signal output from the photoelectric conversion unit 20 into a pulse signal. The waveform shaping unit 32 can be configured using, for example, a NOT circuit (inverter circuit) as shown in FIG. 4. FIG. 4 shows an example in which the waveform shaping unit 32 is configured by one inverter circuit, but the waveform shaping unit 32 may also be configured by a circuit in which a plurality of inverter circuits are connected in series. Further, the waveform shaping unit 32 can be configured not only by a NOT circuit but also by other circuits having a waveform shaping effect, such as a logic circuit including a NOR circuit, a NAND circuit, etc. The output node of the waveform shaping unit 32 is connected to the counter circuit 34.

[0029] The counter circuit 34 has an input node to which the output signal of the waveform shaping unit 32 is input, an input node connected to the control line 14, an output node, and a flip-flop circuit. The counter circuit 34 has a function of counting the pulses superimposed on the signal output from the waveform shaping unit 32 and holding the count value which is the counting result. The signal supplied from the vertical scanning circuit unit 40 to the counter circuit 34 via the control line 14 may include an enable signal for controlling the pulse counting period (exposure period) and a reset signal for resetting the count value held by the counter circuit 34. The output node of the counter circuit 34 is connected to the data line 16 via the selection circuit 36, and outputs a count signal indicating the count value to the data line 16 via the selection circuit 36.

[0030] The selection circuit 36 has a function of switching the electrical connection state (connection or non-connection) between the counter circuit 34 and the data line 16. The selection circuit 36 switches the connection state between the counter circuit 34 and the data line 16 according to the control signal supplied from the vertical scanning circuit unit 40 via the control line 14.

[0031] Note that the pixel signal processing unit 30 does not necessarily have to be provided one by one for each pixel 12, and one pixel signal processing unit 30 may be provided for a plurality of pixels 12. In this case, it can be configured to sequentially execute signal processing of a plurality of pixels 12 using one pixel signal processing unit 30. Further, when the pixel signal processing unit 30 is composed of a waveform shaping unit 32, a counter circuit 34, and a selection circuit 36, each of the pixel signal processing units 30 does not necessarily have to include all of the waveform shaping unit 32, the counter circuit 34, and the selection circuit 36.

[0032] The photoelectric conversion device 100 according to the present embodiment may be formed on a single substrate, or may be configured as a stacked photoelectric conversion device in which a plurality of substrates are stacked. In the latter case, for example, as shown in FIG. 1, it can be configured as a stacked photoelectric conversion device in which a sensor substrate 110 and a circuit substrate 180 are stacked and electrically connected. At least the photoelectric conversion element 22 among the components of the pixel 12 can be arranged on the sensor substrate 110. Further, among the components of the pixel 12, the quench element 24 and the pixel signal processing unit 30 can be arranged on the circuit substrate 180. The photoelectric conversion element 22, the quench element 24, and the pixel signal processing unit 30 are electrically connected via connection wiring provided for each pixel 12. Further, a vertical scanning circuit unit 40, a readout circuit unit 50, a horizontal scanning circuit unit 60, an output circuit unit 70, a control unit 80, etc. can be further arranged on the circuit substrate 180.

[0033] The photoelectric conversion element 22, the quench element 24, and the pixel signal processing unit 30 of each pixel 12 can be provided on the sensor substrate 110 and the circuit substrate 180 so as to overlap in a plan view. The vertical scanning circuit unit 40, the readout circuit unit 50, the horizontal scanning circuit unit 60, the output circuit unit 70, and the control unit 80 can be arranged around a pixel region 10 composed of a plurality of pixels 12. Here, the "plan view" refers to viewing from a direction perpendicular to the surface of the sensor substrate 110.

[0034] By constructing the stacked photoelectric conversion device 100, the integration density of the elements can be increased and the device can be made more functional. In particular, by arranging the photoelectric conversion element 22, the quench element 24, and the pixel signal processing unit 30 on separate substrates, the photoelectric conversion element 22 can be arranged at a high density without sacrificing the light-receiving area of the photoelectric conversion element 22, and the photon detection efficiency can be improved.

[0035] Note that the number of substrates constituting the photoelectric conversion device 100 is not limited to two, and the photoelectric conversion device 100 may be configured by stacking three or more substrates.

[0036] In addition, in FIG. 1, diced chips are assumed as the sensor substrate 110 and the circuit substrate 180, but the sensor substrate 110 and the circuit substrate 180 are not limited to chips. For example, each of the sensor substrate 110 and the circuit substrate 180 may be a wafer. Further, the sensor substrate 110 and the circuit substrate 180 may be diced after being stacked in a wafer state, or may be stacked and bonded after being chipped respectively.

[0037] Next, the basic operation of the photoelectric conversion unit 20 in the photoelectric conversion device 100 according to the present embodiment will be described with reference to FIG. 5. FIG. 5 is a diagram for explaining the basic operation of the photoelectric conversion unit in the photoelectric conversion device 100 according to the present embodiment. FIG. 5(a) is a circuit diagram of the photoelectric conversion element 22, the quench element 24, and the waveform shaping unit 32. FIG. 5(b) shows the waveform of the signal at the input node (node A) of the waveform shaping unit 32, and FIG. 5(c) shows the waveform of the signal at the output node (node B) of the waveform shaping unit 32.

[0038] At time t0, a reverse bias voltage corresponding to (VH - VL) is applied to the photoelectric conversion element 22. A reverse bias voltage sufficient to cause an avalanche multiplication operation is applied between the anode and the cathode of the APD constituting the photoelectric conversion element 22. However, in a state where no photons are incident on the photoelectric conversion element 22, there are no carriers that can serve as seeds for avalanche multiplication. Therefore, avalanche multiplication does not occur in the photoelectric conversion element 22, and no current flows through the photoelectric conversion element 22.

[0039] Subsequently, at time t1, it is assumed that photons are incident on the photoelectric conversion element 22. When photons are incident on the photoelectric conversion element 22, electron-hole pairs are generated by photoelectric conversion. Using these carriers as seeds, avalanche multiplication occurs, and an avalanche multiplication current flows through the photoelectric conversion element 22. When this avalanche multiplication current flows through the quench element 24, a voltage drop occurs across the quench element 24, and the voltage at node A begins to drop. As the voltage drop amount at node A increases and the avalanche multiplication operation stops at time t3, the voltage level at node A no longer drops.

[0040] When the avalanche multiplication operation in the photoelectric conversion element 22 stops, a current flows from the node to which the voltage VL is supplied, through the photoelectric conversion element 22, to compensate for the voltage drop at node A, and the voltage at node A gradually increases. Subsequently, at time t5, node A stabilizes at the original voltage level.

[0041] The waveform shaping unit 32 binarizes the signal input from node A according to a predetermined determination threshold value and outputs it from node B. Specifically, when the voltage level of node A exceeds the determination threshold value, the waveform shaping unit 32 outputs a Low-level signal from node B, and when the voltage level of node A is equal to or lower than the determination threshold value, the waveform shaping unit 32 outputs a High-level signal from node B. For example, as shown in FIG. 5(b), it is assumed that the voltage of node A is equal to or lower than the determination threshold value during the period from time t2 to time t4. In this case, as shown in FIG. 5(c), the signal level at node B becomes Low level during the period from time t0 to time t2 and the period from time t4 to time t5, and becomes High level during the period from time t2 to time t4.

[0042] In this way, the analog signal input from node A is waveform-shaped into a digital signal by the waveform shaping unit 32. The pulse signal output from the waveform shaping unit 32 in response to the incidence of photons on the photoelectric conversion element 22 is the photon detection pulse signal.

[0043] Next, the process for improving the processing speed of the photoelectric conversion device 100 will be described with reference to FIGS. 6 and 7. FIG. 6 is a functional block diagram showing a configuration example of the main part of the photoelectric conversion device 100 according to the present embodiment. In FIG. 6, as the main part of the photoelectric conversion device 100, a pixel region 10, a detection unit 81, a region control unit 82, and an output circuit unit 70 are illustrated, and the flow of processing of these main parts is indicated by arrows. FIG. 7 is a block diagram showing a configuration example of the pixel 12 of the photoelectric conversion device 100 according to the present embodiment.

[0044] The counter circuit 34 has, for example, a flip-flop circuit that can hold 11-bit information. The counter circuit 34 counts the photon detection signals (pulse signals) output from the waveform shaping unit 32 and holds the count value, which is the result of the counting, in the 11-bit flip-flop circuit. The counter circuit 34 outputs a count signal indicating the count value to the readout circuit unit 50 via the selection circuit 36. The counter circuit 34 is switched, for example, to output the upper bit information (CNT

[10] ), which is the information of the most significant bit (MSB) among the 11 bits, to the detection unit 81 via the selection circuit 36 and the readout circuit unit 50. Also, the counter circuit 34 is switched to output all-bit information (CNT[10:0]), which is all the information of the 11 bits, to the output circuit unit 70 via the selection circuit 36 and the readout circuit unit 50. Note that the upper bit information (CNT

[10] ) is an example of the first information, and the all-bit information (CNT[10:0]) is an example of the second information.

[0045] As shown in FIG. 7, the selection circuit 36 includes a first switch circuit 361, a second switch circuit 362, and a buffer circuit (not shown). The buffer circuit has a function of temporarily storing the count signal output from the counter circuit 34.

[0046] The first switch circuit 361 is provided on the data line 16 that connects the counter circuit 34 and the readout circuit unit 50. The first switch circuit 361 switches the connection state between the counter circuit 34 and the detection unit 81 connected to the readout circuit unit 50 according to a control signal supplied from the area control unit 82 via the vertical scanning circuit unit 40. The first switch circuit 361 is turned on, for example, based on the control signal output from the area control unit 82, and causes the upper bit information (CNT

[10] ) to be output from the counter circuit 34 to the detection unit 81. Also, the first switch circuit 361 is turned off based on the control signal output from the area control unit 82, and does not cause the upper bit information (CNT

[10] ) to be output from the counter circuit 34 to the detection unit 81.

[0047] The second switch circuit 362 is provided on the data line 16 that connects the counter circuit 34 and the read circuit section 50. The second switch circuit 362 switches the connection state between the counter circuit 34 and the output circuit section 70 connected to the read circuit section 50 according to a control signal supplied from the area control section 82 via the vertical scanning circuit section 40. The second switch circuit 362 turns on, for example, based on a control signal output from the area control section 82, and causes all-bit information (CNT[10:0]), which is all 11-bit information, to be output from the counter circuit 34 to the output circuit section 70. Also, the second switch circuit 362 turns off based on a control signal output from the area control section 82, and does not cause all-bit information (CNT[10:0]) to be output from the counter circuit 34 to the output circuit section 70.

[0048] The detection section 81 detects a pixel 12 to be read based on the upper-bit information (CNT

[10] ) of each pixel 12 output from the first switch circuit 361. The detection section 81 extracts, for example, the pixel 12 as a detection pixel 12a to be read when the upper-bit information (CNT

[10] ) of the pixel 12 output from the counter circuit 34 is "1", that is, at a High level. Also, the detection section 81 does not extract the pixel 12 as a detection pixel 12a to be read when the upper-bit information (CNT

[10] ) of the pixel 12 output from the counter circuit 34 is "0", that is, at a Low level. When the detection section 81 extracts a detection pixel 12a to be read, the detection section 81 outputs information indicating the coordinate position of the detection pixel 12a to the area control section 82. On the other hand, when the detection section 81 does not extract a detection pixel 12a to be read, the detection section 81 does not output information indicating the coordinate position of the detection pixel 12a to the area control section 82. The area control section 82 controls the area in the pixel area 10 that outputs a pixel signal to the read circuit section 50 based on the information indicating the coordinate position output from the detection section 81.

[0049] Next, a detailed operation example of the region control unit 82 will be described with reference to FIG. 8. FIG. 8 is a diagram showing an operation example (Part 1) of the region control unit 82 of the photoelectric conversion device 100 according to the present embodiment. The region control unit 82 controls a region in the pixel region 10 that outputs a pixel signal to the readout circuit unit 50 based on information indicating the coordinate position output from the detection unit 81. In this case, the region control unit 82 controls so that the number of pixels 12 to be output is larger than the number of pixels 12 detected by the detection unit 81.

[0050] Specifically, as shown in FIG. 8, the region control unit 82 identifies the detected pixels 12a extracted by the detection unit 81 based on the information indicating the coordinate position output from the detection unit 81. In the enlarged view shown in FIG. 8, the detected pixels 12a extracted by the detection unit 81 are denoted as "1", and the non-detected pixels 12b not extracted by the detection unit 81 are denoted as "0". The region control unit 82 identifies adjacent pixels 12c adjacent to the identified detected pixels 12a based on the detected pixels 12a. Specifically, the region control unit 82 identifies non-detected pixels 12b located within a predetermined distance from the detected pixels 12a as adjacent pixels 12c. More specifically, the region control unit 82 identifies non-detected pixels 12b surrounding the periphery of one detected pixel 12a as adjacent pixels 12c. More specifically, the plurality of pixels 12 are arranged on an XY coordinate composed of an X-axis and a Y-axis orthogonal to each other. And, a plurality of adjacent pixels 12c surrounding the periphery of one detected pixel 12a are configured such that at least three adjacent pixels 12c are arranged along the X-axis direction and at least three adjacent pixels 12c are arranged along the Y-axis direction, and have a rectangular shape. These adjacent pixels 12c are basically non-detected pixels 12b not extracted by the detection unit 81. In this way, the detected pixels 12a and their adjacent pixels 12c identified by the region control unit 82 are composed of 3×3 pixels and are formed in a rectangular shape as a whole. In this 3×3 pixel configuration, one detected pixel 12a is located at the center, and eight adjacent pixels 12c are located so as to surround the detected pixel 12a.

[0051] The region control unit 82 sequentially scans the detection pixel 12a and the adjacent pixel 12c in row units via the vertical scanning circuit unit 40. At this time, the region control unit 82 controls the second switch circuits 362 of the detection pixel 12a and the adjacent pixel 12c to output all bit information (CNT[10:0]) of each of the detection pixel 12a and the adjacent pixel 12c to the readout circuit unit 50. The readout circuit unit 50 holds these all bit information (CNT[10:0]) in the holding unit of the corresponding column. The region control unit 82 sequentially scans all bit information (CNT[10:0]) held in the readout circuit unit 50 in column units via the horizontal scanning circuit unit 60, and outputs all bit information (CNT[10:0]) held in each to the output circuit unit 70. Note that, for example, when the photoelectric conversion device 100 is used for distance measurement, the light emitted from the light emitting unit toward the object may be a dot pattern of near-infrared light. In this case, since the dot pattern is circular and has a Gaussian distribution, in order to improve the accuracy of the luminance center of gravity, it is desirable to acquire the pixel signal in a form including the luminance distribution. Also, in a configuration of only one pixel, the effect of sub-pixel rendering cannot be expected so much, and thus a configuration of at least 3×3 pixels is desirable. Further, as shown in FIG. 9, the region control unit 82 may configure the detection pixel 12a and its adjacent pixel 12c as a 5×5 pixel. FIG. 9 is a diagram showing an operation example (part 2) of the region control unit 82 of the photoelectric conversion device 100 according to the present embodiment. By configuring it as a 5×5 pixel, it becomes easy to perform corrections such as aberration correction even when the dot pattern spreads due to lens aberration or the like. Furthermore, a configuration of 3×3 pixels and a configuration of 5×5 pixels may be mixed within the same frame.

[0052] Next, another operation example of the region control unit 82 will be described with reference to FIG. 10. FIG. 10 is a diagram showing an operation example (No. 3) of the region control unit 82 of the photoelectric conversion device 100 according to the present embodiment. In the present embodiment, the region control unit 82 does not specify the adjacent pixel 12c for each detection pixel 12a, but specifies the adjacent pixel 12c for each region based on the region where the detection pixels 12a are concentrated. Here, the concentration means that the number of detection pixels 12a existing per unit area is equal to or more than a predetermined reference number. The region control unit 82 specifies, for example, a non-detection pixel 12b included in a region (for example, a rectangular region shown in FIG. 10) surrounding a portion where the detection pixels 12a are concentrated in the pixel region 10 as the adjacent pixel 12c. Then, the region control unit 82 controls the second switch circuits 362 of the detection pixels 12a and the adjacent pixels 12c included in the region via the vertical scanning circuit unit 40, and outputs all-bit information (CNT[10:0]) toward the readout circuit unit 50. Then, the region control unit 82 controls the horizontal scanning circuit unit 60, and outputs all-bit information (CNT[10:0]) of each of the detection pixels 12a and the adjacent pixels 12c from the readout circuit unit 50 toward the output circuit unit 70. Further, the region control unit 82 controls the second switch circuit 362 of the detection pixel 12a not included in the above region via the vertical scanning circuit unit 40, and outputs all-bit information (CNT[10:0]) toward the readout circuit unit 50. Then, the region control unit 82 controls the horizontal scanning circuit unit 60, and outputs all-bit information (CNT[10:0]) of the detection pixel 12a from the readout circuit unit 50 toward the output circuit unit 70.

[0053] Next, an operation example of the photoelectric conversion device 100 will be described with reference to FIG. 11. FIG. 11 is a timing chart showing an operation example (No. 1) of the photoelectric conversion device 100 according to the present embodiment. As shown in FIG. 11, the photoelectric conversion device 100 starts exposure of the pixels 12 arranged in the first row of the pixel region 10 at time t1, and sequentially performs exposure row by row.

[0054] At time t2, the counter circuit 34 of each pixel 12 arranged in the first row of the pixel region 10 outputs the upper bit information (CNT

[10] ) of the count signal to the detection unit 81. Based on the upper bit information (CNT

[10] ) of the pixels 12 in the first row output from the counter circuit 34, the detection unit 81 extracts the detection pixel 12a to be read.

[0055] At time t3, the counter circuit 34 of each pixel 12 arranged in the M-th row (last row) of the pixel region 10 outputs the upper bit information (CNT

[10] ) of the count signal to the detection unit 81. Based on the upper bit information (CNT

[10] ) of the pixels 12 in the M-th row (last row) output from the counter circuit 34, the detection unit 81 extracts the detection pixel 12a to be read.

[0056] At time t3, based on the detection pixel 12a extracted by the detection unit 81, the region control unit 82 identifies the adjacent pixel 12c adjacent to the detection pixel 12a. Then, the region control unit 82 starts reading the detection pixel 12a and the adjacent pixel 12c. Specifically, the region control unit 82 outputs all bit information (CNT[10:0]) of the detection pixel 12a and the adjacent pixel 12c to the reading circuit unit 50. Then, the region control unit 82 outputs all bit information (CNT[10:0]) output to the reading circuit unit 50 to the output circuit unit 70. In FIG. 11, the arrow part corresponds to the row for reading the detection pixel 12a and the adjacent pixel 12c in the pixel region 10.

[0057] At time t4, the region control unit 82 ends the reading of the detection pixel 12a and the adjacent pixel 12c in frame N. Note that the detection frame for extracting the detection pixel 12a from time t2 to time t3 and the reading frame for reading all bit information (CNT[10:0]) of the detection pixel 12a and the adjacent pixel 12c from time t3 to time t4 constitute one frame (frame N).

[0058] Exposure is started to generate the next frame N+1. After starting the exposure, at time t4, extraction of the detection pixel 12a is started, and at time t5, extraction of the detection pixel 12a is ended. Then, at time t5, reading of the detection pixel 12a and the adjacent pixel 12c is started, and at time t6, reading of the detection pixel 12a and the adjacent pixel 12c is ended. Note that since the adjacent pixel 12c is specified based on the detection pixel 12a, the adjacent pixel 12c may be different between frame N and frame N+1.

[0059] Incidentally, depending on the exposure conditions in the subject, environment, etc., the number of detection pixels 12a in a frame may increase, and accordingly, the number of adjacent pixels 12c may also increase. In this case, when reading the information of the detection pixel 12a and the adjacent pixel 12c and outputting it to the output circuit unit 70, a lot of time is required, which may cause a decrease in the overall processing speed. For this reason, when the number of detection pixels 12a in a frame is large, the reading of the pixels 12 in the frame may be skipped, the exposure period may be shortened, and then the process may proceed to the next frame. FIG. 12 is a timing chart showing an operation example (part 2) of the photoelectric conversion device according to the present embodiment. For example, when the number of detection pixels 12a in frame N is equal to or more than a predetermined reference number of pixels, the area control unit 82 skips the reading of the detection pixel 12a and the adjacent pixel 12c in frame N. Then, the area control unit 82 makes the exposure period of the next frame N+1 shorter than the exposure period of frame N. In FIG. 12, the period from time t1 to time t2 is the exposure period T1 of frame N, and the period from time t3 to time t4 is the exposure period T2 of frame N+1. The exposure period T2 of frame N+1 is made shorter than the exposure period T1 of frame N. In this way, the area control unit 82 controls the exposure period of the photoelectric conversion unit 20 according to the number of detection pixels 12a. Thereby, an increase in the number of detection pixels 12a can be suppressed, and thus a decrease in the overall processing speed can be suppressed.

[0060] As described above, the photoelectric conversion device 100 according to the present embodiment includes a plurality of pixels 12 and a detection unit 81. Each of the plurality of pixels 12 has a photoelectric conversion unit 20, a counter circuit 34, and a selection circuit 36. The photoelectric conversion unit 20 outputs a photon detection signal in response to the incidence of photons. The counter circuit 34 holds a count value obtained by counting the photon detection signal with a predetermined number of bits. The selection circuit 36 switches the information output from the counter circuit 34 to upper-bit information indicating the information of the upper bits among the predetermined number of bits held by the counter circuit 34 or all-bit information indicating the information of all bits. The detection unit 81 extracts a detection pixel 12a, which is a pixel 12 targeted to output all-bit information, from among the plurality of pixels 12 based on the upper-bit information. With this configuration, in the photoelectric conversion device 100 according to the present embodiment, the detection unit 81 can detect the pixel 12 that is targeted to output all-bit information by only checking the upper-bit information. As a result, the detection unit 81 can increase the detection speed as compared with the case of checking all-bit information to extract the detection pixel 12a. In the present embodiment, each pixel 12 has a counter circuit 34, and digital conversion is performed for each pixel 12. Thereby, by reading out only one bit of the upper bits for each pixel 12, it is possible to improve the readout speed to the detection unit 81 as compared with the case of reading out all 11 bits. Further, by checking only the upper bits by the detection unit 81, the influence of dark noise and optical shot noise can be reduced. In this way, the readout speed can be improved without degrading the output accuracy of the signal.

[0061] Also, in the photoelectric conversion device 100, the region control unit 82 controls the selection circuit 36 of the detection pixel 12a extracted by the detection unit 81, and causes the counter circuit 34 of the detection pixel 12a to output all-bit information. Further, the region control unit 82 specifies, as adjacent pixels 12c, non-detection pixels 12b that are located within a predetermined distance from the detection pixel 12a among the non-detection pixels 12b which are pixels 12 not extracted by the detection unit 81. Then, the region control unit 82 controls the selection circuit 36 of the adjacent pixels 12c and also causes the counter circuit 34 of the adjacent pixels 12c to output all-bit information. With this configuration, the photoelectric conversion device 100 can output including the pixels around the detection pixel 12a, so that an object can be accurately output up to a low luminance region, thereby improving the output accuracy. Also, since the photoelectric conversion device 100 reads some pixels 12 (detection pixel 12a and adjacent pixels 12c) of the pixel region 10, the processing speed can be improved as compared with the case of reading all the pixels 12 of the pixel region 10.

[0062] [Second Embodiment] Next, the photoelectric conversion device 100 according to the second embodiment will be described. In the photoelectric conversion device 100 according to the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted. FIG. 13 is a block diagram showing a configuration example of the pixel 12A of the photoelectric conversion device 100 according to the present embodiment. FIG. 14(a) is a diagram showing an output example of the 11-bit detection pixel 12a according to the present embodiment. FIG. 14(b) is a diagram showing an output example of the 11-bit non-detection pixel 12b according to the present embodiment. The pixel 12A according to the present embodiment is different from the pixel 12 according to the first embodiment in that it has a bit selection unit 37.

[0063] The bit selection unit 37 has a function of selecting a predetermined bit from the 11-bit count signal. The bit selection unit 37 is provided on the data line 16 that connects the second switch circuit 362 and the readout circuit unit 50. Based on the control signal output from the area control unit 82, the bit selection unit 37 selects a predetermined bit from all the bit information (CNT[10:0]) output from the counter circuit 34 via the second switch circuit 362. Then, the bit selection unit 37 outputs the selected count signal to the output circuit unit 70 via the readout circuit unit 50. In this case, the bit selection unit 37 makes the number of bits of all the bit information (CNT[10:0]) output from the respective counter circuits 34 different between the detected pixel 12a and the non-detected pixel 12b. Specifically, when the control signal indicating that it is the detected pixel 12a is output from the area control unit 82, the bit selection unit 37 selects a predetermined bit. That is, the bit selection unit 37 selects the remaining upper 8 bits (CNT[10:3]) excluding the lower 3 bits (CNT[2:0]), which are the lower bit information, from all the bit information (CNT[10:0]) (see Fig. 14(a)). Then, the bit selection unit 37 outputs the count signal composed of the upper 8 bits (CNT[10:3]) to the output circuit unit 70 via the readout circuit unit 50. Here, in the case of the detected pixel 12a, since the upper bit is "1", it is assumed that the energy of the light is 1000e or more. In this case, the optical shot noise is about 44e. Therefore, since the lower 3 bits are buried in the optical shot noise, even if the lower 3 bits (equivalent to 8e) are reduced, the influence on the output accuracy is small.

[0064] On the other hand, when the bit selection unit 37 receives a control signal indicating that the pixel is an undetected pixel 12b from the area control unit 82, it selects a predetermined bit. That is, the bit selection unit 37 selects the lower 10 bits (CNT[9:0]) excluding the upper 1 bit (CNT

[10] ), which is the upper bit information, from the entire bit information (CNT[10:0]) (see Fig. 14(b)). Then, the bit selection unit 37 outputs the count signal composed of the lower 10 bits (CNT[9:0]) to the output circuit unit 70 via the readout circuit unit 50. This is because it is known that the upper bit of the undetected pixel 12b is "0", so there is no problem in reducing and outputting the upper bit.

[0065] As described above, in the photoelectric conversion device 100, when the output pixel output to the output circuit unit 70 is the detected pixel 12a, the bit selection unit 37 does not output the lower 3 bits, and when the output pixel is the undetected pixel 12b, the bit selection unit 37 does not output the upper 1 bit. As a result, the photoelectric conversion device 100 can reduce the number of output bits without degrading the output accuracy, and thereby further improve the speed of reading the pixel signals (count signals) of the respective pixels 12 from the readout circuit unit 50.

[0066] [Third Embodiment] Next, the photoelectric conversion device 100B according to the third embodiment will be described. In the photoelectric conversion device 100B according to the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and detailed descriptions thereof are omitted. FIG. 15 is a functional block diagram showing a configuration example of a main part of the photoelectric conversion device 100B according to the present embodiment. In FIG. 15, as a main part of the photoelectric conversion device 100B, in addition to the main part of the photoelectric conversion device 100 shown in FIG. 6, an exposure control unit 83 is further provided. FIG. 16 is a block diagram showing a configuration example of a pixel 12B of the photoelectric conversion device 100B according to the present embodiment. FIG. 17 is a diagram showing an operation example of an edge trigger circuit 39 of the photoelectric conversion device 100B according to the present embodiment. FIG. 18 is a timing chart showing an operation example of the photoelectric conversion device 100B according to the present embodiment. The photoelectric conversion device 100B according to the present embodiment is different from the photoelectric conversion device 100 according to the first and second embodiments in that the number of detection pixels 12a is fixed to suppress a decrease in processing speed.

[0067] Each pixel 12B according to the present embodiment may be composed of, for example, a quench element 24, a waveform shaping unit 32, a counter circuit 34, a second switch circuit 362, a third switch circuit 363, a memory 38, and an edge trigger circuit 39.

[0068] The second switch circuit 362 is provided on the data line 16 between the counter circuit 34 and the memory 38, and has a function of switching the electrical connection state (connection or non-connection) between the counter circuit 34 and the memory 38. The second switch circuit 362 switches the connection state between the counter circuit 34 and the memory 38 according to a control signal supplied from the exposure control unit 83 via the control line 14.

[0069] The third switch circuit 363 is provided on the data line 16 between the memory 38 and the readout circuit unit 50, and has a function of switching the electrical connection state (connection or non-connection) between the memory 38 and the readout circuit unit 50. The third switch circuit 363 switches the connection state between the memory 38 and the readout circuit unit 50 according to a control signal supplied from the region control unit 82 via the control line 14.

[0070] The memory 38 has a function of storing information. The memory 38 is connected to the counter circuit 34 via the second switch circuit 362 and stores the count signal output from the counter circuit 34. Further, the memory 38 is connected to the read circuit section 50 via the third switch circuit 363, and outputs the stored count signal to the output circuit section 70 via the read circuit section 50.

[0071] The edge trigger circuit 39 has a function of detecting a change in the level of a signal indicating the upper bit information (CNT

[10] ). Here, the edge trigger circuit 39 detects the rising edge of the pulse signal. The edge trigger circuit 39 is provided on the data line 16 between the counter circuit 34 and the read circuit section 50. The edge trigger circuit 39 detects that the pulse signal indicating the upper bit (CNT

[10] ) of the count signal output from the counter circuit 34 changes from the Low level to the High level, that is, the upper bit (CNT

[10] ) changes from "0" to "1". For example, as shown in FIG. 17, the edge trigger circuit 39 takes the exclusive logical sum (XOR) of the signal (CNT

[10] ) of the upper bit of the count signal and the delayed signal (CNT

[10] _d) obtained by delaying the signal of the upper bit (CNT

[10] ). Thereby, the edge trigger circuit 39 detects that the upper bit (CNT

[10] ) changes from the Low level to the High level at time t1, and outputs a detection pulse signal TRG indicating the detection result to the detection section 81 via the read circuit section 50.

[0072] Based on the detection pulse signal TRG output from the edge trigger circuit 39, the detection unit 81 stores the coordinate position of the detection pixel 12a and counts the total number of detection pixels 12a. For example, the detection unit 81 has a counter circuit 811, and the counter circuit 811 counts the total number of detection pixels 12a. When the count value counted by the counter circuit 811 is equal to or greater than a predetermined threshold value, the detection unit 81 outputs a control signal indicating that the count value has become equal to or greater than the threshold value to the exposure control unit 83. When the count value counted by the counter circuit 811 is less than the threshold value, the detection unit 81 does not output the control signal to the exposure control unit 83.

[0073] The exposure control unit 83 has a function of controlling the exposure of each pixel 12 for each frame. When a control signal indicating that the count value has become equal to or greater than the threshold value, that is, the number of detection pixels 12a is equal to or greater than a predetermined reference number of pixels, is output from the detection unit 81, the exposure control unit 83 outputs a control signal to each pixel 12 via the vertical scanning circuit unit 40. Then, the exposure control unit 83 controls the quench element 24 with this control signal and stops the process of converting the change in the avalanche current by the photoelectric conversion element 22 into a voltage signal. As a result, the counting process by the counter circuit 34 of each pixel 12 stops. That is, the exposure of all pixels 12 in the target frame stops in the middle of the exposure period. After stopping the counter circuit 34, the exposure control unit 83 turns on the second switch circuit 362 and stores a count signal indicating the count value counted by the counter circuit 34 until just before the stop in the memory 38.

[0074] When the third switch circuit 363 is turned on by the area control unit 82, the memory 38 outputs the stored count signal to the output circuit unit 70 via the readout circuit unit 50.

[0075] Next, an operation example of the photoelectric conversion device 100B will be described with reference to FIG. 18. FIG. 18 is a timing chart showing an operation example of the photoelectric conversion device 100B according to the present embodiment. As shown in FIG. 18, the photoelectric conversion device 100B starts the exposure of frame N at time t1. The edge trigger circuit 39 of each pixel 12 detects that the most significant bit (CNT

[10] ) of the count signal output from the counter circuit 34 changes from the Low level to the High level, and outputs a detection pulse signal indicating the detection result to the detection unit 81.

[0076] The counter circuit 811 of the detection unit 81 counts the total number of detected pixels 12a in frame N based on the detection pulse signal TRG output from the edge trigger circuit 39 (from time t1 to time t2).

[0077] When the count value counted by the counter circuit 811 of the detection unit 81 is equal to or greater than the threshold value, the detection unit 81 outputs a control signal indicating that the count value has become equal to or greater than the threshold value to the exposure control unit 83 (at time t2). When the exposure control unit 83 receives a control signal indicating that the count value has become equal to or greater than the threshold value from the detection unit 81, it stops the exposure by each pixel 12 (at time t2). Then, the exposure control unit 83 causes the memory 38 to store the count signal indicating the count value counted by the counter circuit 34 of each pixel 12. The area control unit 82 outputs the count signal stored in the memory 38 to the output circuit unit 70 (from time t2 to time t4). Note that after the counter circuit 34 of each pixel 12 outputs the count signal to the memory 38, a reset signal is output from the vertical scanning circuit unit 40, and the count value is reset.

[0078] At time t2, the exposure of the next frame N+1 is started. The edge trigger circuit 39 of each pixel 12 detects that the most significant bit (CNT

[10] ) of the count signal output from the counter circuit 34 changes from the Low level to the High level, and outputs a detection pulse signal TRG indicating the detection result to the detection unit 81.

[0079] The counter circuit 811 of the detection unit 81 counts the total number of detected pixels 12a in frame N + 1 based on the detection pulse signal output from the edge trigger circuit 39 (from time t2 to time t4).

[0080] When the count value of frame N + 1 counted by the counter circuit 811 of the detection unit 81 is equal to or greater than the threshold value, the detection unit 81 outputs a control signal indicating that the count value has become equal to or greater than the threshold value to the exposure control unit 83 (at time t3). Time t3 is a time during the exposure period (from time t2 to time t4) in frame N + 1. During the period from time t2 to time t3, the overall light amount increases, indicating a case where the detected pixels 12a in frame N + 1 increase in a shorter period than the detected pixels 12a in frame N. During this period, the total number of detected pixels 12a in frame N + 1 becomes equal to or greater than the threshold value during the exposure period (from time t2 to time t4) in frame N + 1. When a control signal indicating that the count value has become equal to or greater than the threshold value is output from the detection unit 81, the exposure control unit 83 stops the exposure of each pixel 12 in frame N + 1 even during the exposure period. That is, the counter circuit 34 of each pixel 12 stops. Then, after the end of the exposure period of frame N + 1 (at time t4), the exposure control unit 83 causes the memory 38 to store a count signal indicating the count value counted by the counter circuit 34 of each pixel 12. The area control unit 82 outputs the count signal stored in the memory 38 to the output circuit unit 70 (from time t4 to time t5). Note that after the counter circuit 34 outputs the count signal to the memory 38, a reset signal is output from the vertical scanning circuit unit 40, and the count value is reset. At time t4, the exposure of the next frame N + 2 starts, and the same processing as described above is repeated. Note that although the counter circuit 34 of each pixel 12 stops at time t3, the count signal of frame N + 1 is not output from the counter circuit 34 to the memory 38 until time t4 when the process of reading the count signal of frame N stored in the memory 38 ends. At time t4 when the process of reading the count signal of frame N ends, the count signal of frame N + 1 is output to the memory 38.

[0081] As described above, when the number of detected pixels 12a is equal to or greater than a predetermined reference number of pixels based on the detection result by the edge trigger circuit 39, the exposure control unit 83 stops the exposure of all the pixels in the target frame midway. The region control unit 82 controls the selection circuit 36 of the detected pixels 12a in the target frame where the exposure has been stopped midway, causes the counter circuit 34 of the detected pixels 12a to output all-bit information, and proceeds to the next frame. Thereby, the exposure period can be optimized for each frame, and the number of detected pixels 12a can be made constant. Then, as the number of detected pixels 12a increases, it becomes possible to prevent the number of read pixels from the output circuit unit 70 from increasing and the read period from becoming long. Also, by providing the memory 38, the reading operation by the detection unit 81 and the output operation of the output circuit unit 70 can be performed simultaneously, and the reading speed can be improved. Further, a global shutter operation becomes possible, and by synchronizing with the emission of light such as a laser or an LED, it becomes possible to remove the influence of external light and further improve the output accuracy of the signal.

[0082] [Fourth Embodiment] The optical detection system according to the fourth embodiment of the present invention will be described with reference to FIG. 19. FIG. 19 is a block diagram showing a schematic configuration of the optical detection system according to the present embodiment. In the present embodiment, an optical detection sensor to which the photoelectric conversion device 100 of the first to third embodiments is applied will be described.

[0083] The photoelectric conversion device 100 described in the first to third embodiments above is applicable to various optical detection systems. Examples of applicable optical detection systems include imaging systems such as digital still cameras, digital camcorders, surveillance cameras, copiers, fax machines, mobile phones, in-vehicle cameras, and observation satellites. Also, a camera module including an optical system such as a lens and an imaging device is included in the optical detection system. FIG. 13 illustrates a block diagram of a digital still camera as an example of these.

[0084] The light detection system 200 illustrated in FIG. 13 includes a photoelectric conversion device 201, a lens 202 that forms an optical image of a subject on the photoelectric conversion device 201, a diaphragm 204 for variably controlling the amount of light passing through the lens 202, and a barrier 206 for protecting the lens 202. The lens 202 and the diaphragm 204 are an optical system that condenses light on the photoelectric conversion device 201. The photoelectric conversion device 201 is the photoelectric conversion device 100 described in any of the first to third embodiments, and converts the optical image formed by the lens 202 into image data.

[0085] The light detection system 200 also includes a signal processing unit 208 that processes the output signal output from the photoelectric conversion device 201. The signal processing unit 208 generates image data from the digital signal output by the photoelectric conversion device 201. Further, the signal processing unit 208 performs various corrections and compressions as necessary to output the image data. The photoelectric conversion device 201 may include an AD conversion unit that generates the digital signal processed by the signal processing unit 208. The AD conversion unit may be formed on the semiconductor layer (semiconductor substrate) on which the photon detection element of the photoelectric conversion device 201 is formed, or may be formed on a semiconductor substrate different from the semiconductor layer on which the photon detection element of the photoelectric conversion device 201 is formed. Further, the signal processing unit 208 may be formed on the same semiconductor substrate as the photoelectric conversion device 201.

[0086] The light detection system 200 further includes a buffer memory unit 210 for temporarily storing image data, and an external interface unit (external I / F unit) 212 for communicating with an external computer or the like. Further, the light detection system 200 includes a recording medium 214 such as a semiconductor memory for recording or reading imaging data, and a recording medium control interface unit (recording medium control I / F unit) 216 for recording or reading from the recording medium 214. Note that the recording medium 214 may be built into the light detection system 200 or may be detachable. Further, the communication between the recording medium control I / F unit 216 and the recording medium 214 and the communication from the external I / F unit 212 may be performed wirelessly.

[0087] Furthermore, the light detection system 200 includes an overall control and arithmetic unit 218 that controls various operations and the entire digital still camera, and a timing generation unit 220 that outputs various timing signals to the photoelectric conversion device 201 and the signal processing unit 208. Here, timing signals and the like may be input from the outside, and the light detection system 200 may have at least the photoelectric conversion device 201 and a signal processing unit 208 that processes the output signal output from the photoelectric conversion device 201. The timing generation unit 220 may be mounted on the photoelectric conversion device 201. Also, the overall control and arithmetic unit 218 and the timing generation unit 220 may be configured to implement part or all of the control functions of the photoelectric conversion device 201.

[0088] The photoelectric conversion device 201 outputs an imaging signal to the signal processing unit 208. The signal processing unit 208 performs predetermined signal processing on the imaging signal output from the photoelectric conversion device 201 and outputs image data. The signal processing unit 208 generates an image using the imaging signal. The signal processing unit 208 may be configured to perform a distance measurement operation on the signal output from the photoelectric conversion device 201.

[0089] As described above, according to this embodiment, by configuring a light detection system using the photoelectric conversion device of the first to third embodiments, a light detection system capable of acquiring higher-quality images can be realized.

[0090] [Fifth Embodiment] The distance image sensor according to the fifth embodiment of the present invention will be described with reference to FIG. 20. FIG. 20 is a block diagram showing a schematic configuration of the distance image sensor according to this embodiment. In this embodiment, a distance image sensor will be described as an example of a light detection system to which the photoelectric conversion device 100 described in the first to third embodiments is applied.

[0091] As shown in FIG. 14, the distance image sensor 300 according to this embodiment may be configured to include an optical system 302, a photoelectric conversion device 304, an image processing circuit 306, a monitor 308, and a memory 310. This distance image sensor 300 receives light (modulated light or pulsed light) that is irradiated from the light source device 320 toward the subject 330 and reflected by the surface of the subject 330, and acquires a distance image corresponding to the distance to the subject 330.

[0092] The optical system 302 is composed of one or more lenses and has a role of forming an image of image light (incident light) from the subject 330 on the light receiving surface (sensor unit) of the photoelectric conversion device 304.

[0093] The photoelectric conversion device 304 is the photoelectric conversion device 100 described in any of the first to third embodiments, and has a function of generating a distance signal indicating the distance to the subject 330 based on the image light from the subject 330 and supplying the generated distance signal to the image processing circuit 306.

[0094] The image processing circuit 306 has a function of performing image processing for constructing a distance image based on the distance signal supplied from the photoelectric conversion device 304.

[0095] The monitor 308 has a function of displaying the distance image (image data) obtained by the image processing in the image processing circuit 306. Also, the memory 310 has a function of storing (recording) the distance image (image data) obtained by the image processing in the image processing circuit 306.

[0096] Thus, according to this embodiment, by configuring a distance image sensor using the photoelectric conversion device of the first to third embodiments, a distance image sensor capable of acquiring a distance image including more accurate distance information can be realized in combination with the improvement of the characteristics of pixel 12.

[0097] [Sixth Embodiment] The endoscopic surgery system according to the sixth embodiment of the present invention will be described with reference to FIG. 21. FIG. 21 is a schematic diagram showing a configuration example of the endoscopic surgery system according to the present embodiment. In the present embodiment, an endoscopic surgery system will be described as an example of an optical detection system to which the photoelectric conversion device 100 described in the first to third embodiments is applied.

[0098] FIG. 21 shows a state where an operator (doctor) 460 is performing surgery on a patient 472 on a patient bed 470 using an endoscopic surgery system 400.

[0099] As shown in FIG. 21, the endoscopic surgery system 400 of the present embodiment may include an endoscope 410, a surgical instrument 420, and a cart 430 on which various devices for endoscopic surgery are mounted. The cart 430 may be equipped with a CCU (Camera Control Unit) 432, a light source device 434, an input device 436, a treatment instrument control device 438, a display device 440, and the like.

[0100] The endoscope 410 includes a lens barrel 412 whose tip region of a predetermined length is inserted into the body cavity of the patient 472, and a camera head 414 connected to the proximal end of the lens barrel 412. FIG. 21 shows an endoscope 410 configured as a so-called rigid endoscope having a rigid lens barrel 412, but the endoscope 410 may be configured as a so-called flexible endoscope having a flexible lens barrel. The endoscope 410 is held in a movable state by an arm 416.

[0101] An opening in which an objective lens is fitted is provided at the tip of the lens barrel 412. A light source device 434 is connected to the endoscope 410, and the light generated by the light source device 434 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 412 and irradiated toward the observation target in the body cavity of the patient 472 through the objective lens. Note that the endoscope 410 may be a direct-view endoscope, or may be an oblique-view endoscope or a side-view endoscope.

[0102] Inside the camera head 414, an optical system and a photoelectric conversion device (not shown) are provided, and the reflected light (observation light) from the observation target is condensed onto the photoelectric conversion device by the optical system. The photoelectric conversion device photoelectrically converts the observation light and generates an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image. As the photoelectric conversion device, the photoelectric conversion device 100 described in any of the first to third embodiments can be used. The image signal is transmitted to the CCU 432 as RAW data.

[0103] The CCU 432 is composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 410 and the display device 440. Further, the CCU 432 receives an image signal from the camera head 414, and performs various image processes for displaying an image based on the image signal, such as development processing (demosaicing processing), on the image signal.

[0104] The display device 440 displays an image based on the image signal on which image processing has been performed by the CCU 432 under the control of the CCU 432.

[0105] The light source device 434 is composed of a light source such as an LED (Light Emitting Diode), and supplies irradiation light for photographing the surgical site or the like to the endoscope 410.

[0106] The input device 436 is an input interface for the endoscope surgical system 400. The user can input various information and instruction inputs to the endoscope surgical system 400 via the input device 436.

[0107] The treatment instrument control device 438 controls the drive of the energy treatment instrument 450 for tissue cauterization, incision, or blood vessel sealing.

[0108] The light source device 434 that supplies the irradiation light for photographing the surgical site with the endoscope 410 can be composed of, for example, an LED, a laser light source, or a white light source composed of a combination thereof. When a white light source is composed of a combination of RGB laser light sources, since the output intensity and output timing of each color (each wavelength) can be controlled with high precision, the white balance of the captured image can be adjusted in the light source device 434. Further, in this case, the laser light from each of the RGB laser light sources is irradiated to the observation target in a time-division manner, and by controlling the driving of the imaging element of the camera head 414 in synchronization with the irradiation timing, it is also possible to capture images corresponding to each of RGB in a time-division manner. According to this method, a color image can be obtained without providing a color filter on the imaging element.

[0109] Further, the driving of the light source device 434 may be controlled so as to change the intensity of the output light at predetermined time intervals. By controlling the driving of the imaging element of the camera head 414 in synchronization with the timing of the change in the intensity of the light and acquiring images in a time-division manner and synthesizing the images, it is possible to generate an image with a high dynamic range without so-called black crush and white clip.

[0110] Further, the light source device 434 may be configured to be able to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependence of light absorption in body tissue is utilized. Specifically, by irradiating light with a narrower band than the irradiation light (i.e., white light) during normal observation, a predetermined tissue such as blood vessels in the mucosal surface layer can be photographed with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image by fluorescence generated by irradiating excitation light. In fluorescence observation, it is possible to irradiate the body tissue with excitation light and observe the fluorescence from the body tissue, or to locally inject a reagent such as indocyanine green (ICG) into the body tissue and irradiate the body tissue with excitation light corresponding to the fluorescence wavelength of the reagent to obtain a fluorescence image. The light source device 434 can be configured to be able to supply such narrow-band light and / or excitation light corresponding to special light observation.

[0111] As described above, according to the present embodiment, by configuring an endoscopic surgery system using the photoelectric conversion devices of the first to third embodiments, an endoscopic surgery system capable of acquiring higher-quality images can be realized.

[0112] [Seventh Embodiment] A light detection system and a moving body according to the seventh embodiment of the present invention will be described with reference to FIGS. 22 to 24. FIG. 22 is a schematic diagram showing a configuration example of the moving body according to the present embodiment. FIG. 23 is a block diagram showing a schematic configuration of the light detection system according to the present embodiment. FIG. 24 is a flowchart showing the operation of the light detection system according to the present embodiment. In the present embodiment, an application example to an in-vehicle camera is shown as a light detection system to which the photoelectric conversion device 100 described in the first to third embodiments is applied.

[0113] FIG. 22 is a schematic diagram showing a configuration example of a moving body (vehicle system) according to the present embodiment. FIG. 22 shows a configuration of a vehicle 500 (automobile) as an example of a vehicle system in which a light detection system to which the photoelectric conversion device described in the first to third embodiments is applied is incorporated. FIG. 22(a) is a front schematic diagram of the vehicle 500, FIG. 22(b) is a plan schematic diagram of the vehicle 500, and FIG. 22(c) is a rear schematic diagram of the vehicle 500. The vehicle 500 is provided with a pair of photoelectric conversion devices 502 on the front. Here, the photoelectric conversion device 502 is the photoelectric conversion device 100 described in any of the first to third embodiments. The vehicle 500 also includes an integrated circuit 503, an alarm device 512, and a main control unit 513.

[0114] FIG. 23 is a block diagram showing a configuration example of an optical detection system 501 mounted on a vehicle 500. The optical detection system 501 includes a photoelectric conversion device 502, an image preprocessing unit 515, an integrated circuit 503, and an optical system 514. The photoelectric conversion device 502 is the photoelectric conversion device 100 described in the first embodiment. The optical system 514 forms an optical image of a subject on the photoelectric conversion device 502. The photoelectric conversion device 502 converts the optical image of the subject formed by the optical system 514 into an electrical signal. The image preprocessing unit 515 performs predetermined signal processing on the signal output from the photoelectric conversion device 502. The function of the image preprocessing unit 515 may be incorporated in the photoelectric conversion device 502. In the optical detection system 501, at least two sets of the optical system 514, the photoelectric conversion device 502, and the image preprocessing unit 515 are provided, and the output from each image preprocessing unit 515 is input to the integrated circuit 503.

[0115] The integrated circuit 503 is an integrated circuit for imaging system applications and includes an image processing unit 504, an optical ranging unit 506, a disparity calculation unit 507, an object recognition unit 508, and an abnormality detection unit 509. The image processing unit 504 processes the image signal output from the image preprocessing unit 515. For example, the image processing unit 504 performs image processing such as development processing and defect correction on the output signal of the image preprocessing unit 515. The image processing unit 504 includes a memory 505 for temporarily holding the image signal. In the memory 505, for example, the positions of known defective pixels in the photoelectric conversion device 502 can be stored.

[0116] The optical ranging unit 506 performs focusing and ranging of the subject. The disparity calculation unit 507 calculates ranging information (distance information) from a plurality of image data (disparity images) acquired by a plurality of photoelectric conversion devices 502. Each of the photoelectric conversion devices 502 may be configured to be able to acquire various information such as distance information. The object recognition unit 508 recognizes subjects such as vehicles, roads, signs, and people. When the abnormality detection unit 509 detects an abnormality in the photoelectric conversion device 502, it notifies the main control unit 513 of the abnormality.

[0117] The integrated circuit 503 may be implemented by dedicatedly designed hardware, by software modules, or by a combination thereof. It may also be implemented by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), etc., or by a combination thereof.

[0118] The main control unit 513 comprehensively controls the operations of the optical detection system 501, the vehicle sensor 510, the control unit 520, etc. Note that the vehicle 500 may not be equipped with the main control unit 513. In this case, the photoelectric conversion device 502, the vehicle sensor 510, and the control unit 520 transmit and receive control signals via a communication network. For example, the CAN standard may be applied to the transmission and reception of these control signals.

[0119] The integrated circuit 503 has a function of receiving a control signal from the main control unit 513 or transmitting a control signal and a set value to the photoelectric conversion device 502 by its own control unit.

[0120] The optical detection system 501 is connected to the vehicle sensor 510 and can detect the running state of the host vehicle such as vehicle speed, yaw rate, and steering angle, as well as the state of the external environment of the host vehicle and other vehicles / obstacles. The vehicle sensor 510 is also a distance information acquisition means for acquiring distance information to an object. In addition, the optical detection system 501 is connected to a driving assistance control unit 511 that performs various driving assistances such as automatic steering, automatic cruise, and collision prevention functions. In particular, regarding the collision determination function, based on the detection results of the optical detection system 501 and the vehicle sensor 510, the collision estimation and the presence or absence of a collision with other vehicles / obstacles are determined. Thereby, avoidance control when a collision is estimated and activation of a safety device at the time of a collision are performed.

[0121] In addition, the light detection system 501 is also connected to an alarm device 512 that issues an alarm to the driver based on the determination result of the collision determination unit. For example, when the collision determination unit determines that there is a high possibility of a collision, the main control unit 513 performs vehicle control such as applying the brakes, returning the accelerator, and suppressing the engine output to avoid the collision and reduce the damage. The alarm device 512 warns the user by sounding an alarm such as a sound, displaying alarm information on a display screen of a display unit such as a car navigation system or a meter panel, or applying vibration to a seat belt or a steering wheel.

[0122] In this embodiment, the light detection system 501 captures an image of the surroundings of the vehicle, for example, the front or the rear. FIG. 22(b) shows an example of the arrangement of the light detection system 501 when the front of the vehicle is imaged by the light detection system 501.

[0123] As described above, the photoelectric conversion device 502 is arranged in front of the vehicle 500. Specifically, when two photoelectric conversion devices 502 are arranged symmetrically with respect to the center line of the vehicle 500 in the advancing / retreating direction or the outer shape (for example, the vehicle width) of the vehicle 500 as the axis of symmetry, it is preferable for acquiring distance information between the vehicle 500 and the object to be photographed and for determining the possibility of a collision. In addition, the photoelectric conversion device 502 is preferably arranged so as not to obstruct the driver's view when the driver visually recognizes the situation outside the vehicle 500 from the driver's seat. The alarm device 512 is preferably arranged so as to easily enter the driver's field of view.

[0124] Next, the failure detection operation of the photoelectric conversion device 502 in the light detection system 501 will be described with reference to FIG. 24. The failure detection operation of the photoelectric conversion device 502 can be performed according to steps S110 to S180 shown in FIG. 24.

[0125] Step S110 is a step of setting the photoelectric conversion device 502 at startup. That is, settings for the operation of the photoelectric conversion device 502 are transmitted from the outside of the light detection system 501 (for example, the main control unit 513) or from inside the light detection system 501, and the imaging operation and the failure detection operation of the photoelectric conversion device 502 are started.

[0126] Next, in step S120, a pixel signal is acquired from the effective pixels. Also, in step S130, an output value from the failure detection pixels provided for failure detection is acquired. These failure detection pixels include a photoelectric conversion element, just like the effective pixels. A predetermined voltage is written to this photoelectric conversion element. The failure detection pixels output a signal corresponding to the voltage written to this photoelectric conversion element. Note that steps S120 and S130 may be reversed.

[0127] Next, in step S140, a non - determination is made between the output expected value of the failure detection pixels and the output value from the actual failure detection pixels. As a result of the non - determination in step S140, if the output expected value and the actual output value match, the process proceeds to step S150, where it is determined that the imaging operation is being performed normally, and the processing steps proceed to step S160. In step S160, the pixel signals of the scanning line are transmitted to the memory 505 for primary storage. Then, the process returns to step S120 to continue the failure detection operation. On the other hand, as a result of the non - determination in step S140, if the output expected value and the actual output value do not match, the processing steps proceed to step S170. In step S170, it is determined that there is an abnormality in the imaging operation, and an alarm is notified to the main control unit 513 or the alarm device 512. The alarm device 512 causes the display unit to display that an abnormality has been detected. Thereafter, in step S180, the photoelectric conversion device 502 is stopped, and the operation of the light detection system 501 is terminated.

[0128] Note that in this embodiment, an example of looping the flowchart for each row has been illustrated, but the flowchart may be looped for every plurality of rows, or the failure detection operation may be performed for each frame. The alarm in step S170 may be notified outside the vehicle via a wireless network.

[0129] In addition, in this embodiment, control to avoid collisions with other vehicles has been described, but the present invention is also applicable to control for automatically driving while following other vehicles, control for automatically driving so as not to deviate from the lane, and the like. Furthermore, the light detection system 501 can be applied not only to vehicles such as the host vehicle, but also to moving bodies (mobile devices) such as ships, aircraft, or industrial robots. In addition, the present invention can be applied not only to moving bodies, but also to devices that widely utilize object recognition, such as advanced road traffic systems (ITS).

[0130] [Eighth Embodiment] The light detection system according to the eighth embodiment of the present invention will be described with reference to FIG. 25. FIG. 25 is a schematic diagram showing a configuration example of the light detection system according to the present embodiment. In the present embodiment, an application example to glasses (smart glasses) will be described as a light detection system to which the photoelectric conversion device 100 described in the first to third embodiments is applied.

[0131] FIG. 25(a) shows glasses 600 (smart glasses) according to one application example. The glasses 600 include a lens 601, a photoelectric conversion device 602, and a control device 603.

[0132] The photoelectric conversion device 602 is the photoelectric conversion device 100 described in any of the first to third embodiments, and is provided on the lens 601. The number of photoelectric conversion devices 602 may be one or more. When a plurality of photoelectric conversion devices 602 are used, a plurality of types of photoelectric conversion devices 602 may be combined and used. The arrangement position of the photoelectric conversion device 602 is not limited to that shown in FIG. 25(a). A display device (not shown) including a light emitting device such as an OLED or an LED may be provided on the back side of the lens 601.

[0133] The control device 603 functions as a power source that supplies power to the photoelectric conversion device 602 and the above-described display device. The control device 603 also has a function of controlling the operations of the photoelectric conversion device 602 and the display device. The lens 601 is provided with an optical system for condensing light onto the photoelectric conversion device 602.

[0134] FIG. 25(b) shows glasses 610 (smart glasses) according to another application example. The glasses 610 include a lens 611 and a control device 612. The control device 612 may be equipped with a photoelectric conversion device (not shown) corresponding to the photoelectric conversion device 602 and a display device.

[0135] The lens 611 is provided with a photoelectric conversion device in the control device 612 and an optical system for projecting light from the display device, and an image is projected. The control device 612 functions as a power source for supplying power to the photoelectric conversion device and the display device, and has a function of controlling the operations of the photoelectric conversion device and the display device.

[0136] The control device 612 may further include a line-of-sight detection unit for detecting the wearer's line of sight. In this case, an infrared light emitting unit is provided in the control device 612, and the infrared light emitted from the infrared light emitting unit can be used for detecting the line of sight. Specifically, the infrared light emitting unit emits infrared light to the eyeball of the user who is gazing at the display image. The imaging unit having a light receiving element detects the reflected light of the emitted infrared light from the eyeball, and thus an imaging image of the eyeball is obtained. By having a reducing means for reducing the light from the infrared light emitting unit to the display unit in a plan view, a decrease in image quality can be reduced.

[0137] The user's line of sight with respect to the display image can be detected from the imaging image of the eyeball obtained by imaging the infrared light. Any known method can be applied to the line-of-sight detection using the imaging image of the eyeball. As an example, a line-of-sight detection method based on the Purkinje image by reflection of the irradiation light on the cornea can be used. More specifically, a line-of-sight detection process based on the pupillary corneal reflex method is performed. Using the pupillary corneal reflex method, a line-of-sight vector representing the orientation (rotation angle) of the eyeball is calculated based on the image of the pupil and the Purkinje image included in the imaging image of the eyeball, and thus the user's line of sight is detected.

[0138] The display device according to this embodiment may include a photoelectric conversion device having a light receiving element, and may be configured to control a display image based on the user's line-of-sight information from the photoelectric conversion device. Specifically, the display device determines a first visual field region that the user gazes at and a second visual field region other than the first visual field region based on the line-of-sight information. The first visual field region and the second visual field region may be determined by the control device of the display device or may be determined by an external control device. When determined by an external control device, it is transmitted to the display device via communication. In the display area of the display device, the display resolution of the first visual field region may be controlled to be higher than that of the second visual field region. That is, the resolution of the second visual field region may be lower than that of the first visual field region.

[0139] Further, the display area may include a first display area and a second display area different from the first display area, and may be configured to determine a region with a higher priority from the first display area and the second display area based on the line-of-sight information. The first display area and the second display area may be determined by the control device of the display device or may be determined by an external control device. When determined by an external control device, it is transmitted to the display device via communication. The resolution of the region with a higher priority may be controlled to be higher than that of the region other than the region with a higher priority. That is, the resolution of the region with a relatively lower priority may be lowered.

[0140] Note that AI may be used to determine the first visual field region or the region with a higher priority. AI may be a model configured to estimate the angle of the line of sight and the distance to the object at the tip of the line of sight from an image of the eyeball using the image of the eyeball and the direction in which the eyeball of the image is actually looking as teacher data. The AI program may be possessed by the display device, the photoelectric conversion device, or an external device. When possessed by an external device, it is transmitted to the display device via communication.

[0141] When performing display control based on visual recognition detection, it is preferably applicable to smart glasses further having a photoelectric conversion device for imaging the outside. The smart glasses can display the captured external information in real time.

[0142] [Modification Embodiment] The present invention is not limited to the above embodiments and can be variously modified. For example, an example in which a part of the configuration of one embodiment is added to another embodiment or an example in which a part of the configuration of another embodiment is replaced is also an embodiment of the present invention.

[0143] Also, the circuit configuration of pixel 12 is not limited to the above embodiment. For example, a switch such as a transistor may be provided between the photoelectric conversion element 22 and the quench element 24 or between the photoelectric conversion unit 20 and the pixel signal processing unit 30 (waveform shaping unit 32) to control the electrical connection state therebetween. Further, a switch such as a transistor may be provided between the node to which the voltage VH is supplied and the quench element 24 and / or between the node to which the voltage VL is supplied and the photoelectric conversion element 22 to control the electrical connection state therebetween.

[0144] Also, in the above embodiment, a configuration using the counter circuit 34 as the pixel signal processing unit 30 is shown, but a TDC (Time to Digital Converter) and a memory may be used instead of the counter circuit 34. In this case, the generation timing of the pulse signal output from the waveform shaping unit 32 is converted into a digital signal by the TDC. A control pulse pREF (reference signal) is supplied to the TDC from the vertical scanning circuit unit 40 via the control line 14 when measuring the timing of the pulse signal. The TDC acquires, as a digital signal, a signal when the input timing of the signal output from each pixel 12 is a relative time with reference to the control pulse pREF.

[0145] Also, in the above embodiment, a configuration in which one pixel 12 has one photoelectric conversion element 22 is shown, but one pixel 12 may have a plurality of photoelectric conversion elements 22.

[0146] In addition, although the second information has been described by taking an example of using all-bit information (CNT[10:0]), it does not necessarily have to be configured to include all-bit information (CNT[10:0]). For example, the second information may be configured to include information of upper bits and information of other bits among a predetermined number of bits.

[0147] Note that each of the above embodiments merely shows examples of implementation of the present invention, and the technical scope of the present invention should not be construed as being limited thereby. That is, the present invention can be implemented in various forms without departing from its technical idea or its main features.

[0148] The disclosure of the above embodiments includes the following configurations. (Configuration 1) A plurality of pixels each having a photoelectric conversion unit that outputs a photodetector signal in response to incidence of photons, a counting unit that holds a count value obtained by counting the photodetector signal with a predetermined number of bits, and a switching unit that switches information output from the counting unit to first information including information of upper bits or second information including information of upper bits and information of other bits among the predetermined number of bits held by the counting unit, and a detection unit that extracts a detection pixel, which is a pixel to output the second information, from among the plurality of pixels based on the first information. A photoelectric conversion device characterized by the above. (Configuration 2) When the first information is at a High level, the detection unit extracts the pixel as the detection pixel, and when the first information is at a Low level, the detection unit does not extract the pixel as the detection pixel. The photoelectric conversion device according to Configuration 1, characterized by the above. (Configuration 3) The photoelectric conversion device further includes a region control unit that controls the switching unit of each pixel based on a detection result of the detection unit. The region control unit causes the second information to be output from the counting units of the detection pixel and adjacent pixels adjacent to the detection pixel. The photoelectric conversion device according to Configuration 1 or 2, characterized by the above. (Configuration 4) The area control unit controls the switching unit of the detection pixel, causes the second information to be output from the counting unit of the detection pixel, and, among non-detection pixels that are pixels not extracted by the detection unit, identifies non-detection pixels located within a predetermined distance from the detection pixel as the adjacent pixels, controls the switching unit of the adjacent pixels, and causes the second information to also be output from the counting unit of the adjacent pixels. The photoelectric conversion device according to Configuration 3, characterized in that. (Configuration 5) The area control unit identifies non-detection pixels surrounding the periphery of one detection pixel as the adjacent pixels. The photoelectric conversion device according to Configuration 3 or 4, characterized in that. (Configuration 6) The plurality of pixels are arranged on an XY coordinate composed of an X-axis and a Y-axis orthogonal to each other. Among the plurality of adjacent pixels surrounding the periphery of one detection pixel, at least three adjacent pixels are arranged along the X-axis direction and at least three adjacent pixels are arranged along the Y-axis direction, and they are configured to have a rectangular shape. The photoelectric conversion device according to Configuration 5, characterized in that. (Configuration 7) The area control unit identifies non-detection pixels included in an area surrounding a portion where the detection pixels are concentrated as the adjacent pixels. The photoelectric conversion device according to any one of Configurations 4 to 6, characterized in that. (Configuration 8) The area control unit makes the number of bits of the second information output from the respective counting units different between the detection pixels extracted by the detection unit and non-detection pixels that are pixels not extracted by the detection unit. The photoelectric conversion device according to any one of Configurations 3 to 7, characterized in that. (Configuration 9) When the area control unit outputs the second information from the counting unit of the detection pixel, it causes the remaining bit information excluding the lower bit information from the second information to be output. The photoelectric conversion device according to Configuration 8, characterized in that. (Configuration 10) When the area control unit outputs the second information from the counting unit of the undetected pixels, it causes the remaining bit information obtained by removing the first information from the second information to be output. The photoelectric conversion device according to Configuration 8 or 9, characterized by the above. (Configuration 11) The area control unit controls the exposure period of the photoelectric conversion unit according to the number of detected pixels. The photoelectric conversion device according to any one of Configurations 3 to 10, characterized by the above. (Configuration 12) Further includes an exposure control unit that controls the exposure of each pixel for each frame. Each of the plurality of pixels has an edge trigger circuit that detects a change in the level of a signal indicating the first information. When the number of detected pixels is equal to or greater than a predetermined reference number of pixels based on the detection result by the edge trigger circuit, the exposure control unit stops the exposure of all the pixels in the target frame. The area control unit controls the switching unit of the detected pixels in the target frame where the exposure has been stopped midway, causes the second information to be output from the counting unit of the detected pixels, and shifts to the next frame. The photoelectric conversion device according to any one of Configurations 3 to 11, characterized by the above. (Configuration 13) The second information includes information of all bits among the predetermined number of bits. The photoelectric conversion device according to any one of Configurations 1 to 7, 11, and 12, characterized by the above. (Configuration 14) The photoelectric conversion device according to any one of Configurations 1 to 13, and a signal processing device that processes a signal output from the photoelectric conversion device. A light detection system characterized by including the above. (Configuration 15) The signal processing device generates a distance image representing distance information to an object based on the signal. The light detection system according to Configuration 14, characterized by the above. (Configuration 16) A moving body, a photoelectric conversion device according to any one of Configurations 1 to 13, distance information acquisition means for acquiring distance information to an object from a parallax image based on a signal output from the photoelectric conversion device, control means for controlling the moving body based on the distance information, and a moving body characterized by comprising the same.

Explanation of Signs

[0149] 12… pixel 20… photoelectric conversion unit 34… counter circuit 36… selection circuit 81… detection unit 82… region control unit 83… exposure control unit

Claims

1. A photoelectric conversion unit that outputs a photodetector signal in response to the incidence of photons, a counting unit that holds a count value obtained by counting the photodetector signal in a predetermined number of bits, and information output from the counting unit, among the predetermined number of bits held by the counting unit, a switching unit that switches between first information including information of upper bits or second information including information of the upper bits and information of other bits, a plurality of pixels each having the above, A detection unit that extracts a detection pixel, which is a pixel that outputs the second information, from among the plurality of pixels based on the first information, and A photoelectric conversion device characterized by the above.

2. When the first information is at a high level, the detection unit extracts the pixel as the detection pixel, and when the first information is at a low level, the detection unit does not extract the pixel as the detection pixel. The photoelectric conversion device according to claim 1, characterized by the above.

3. The photoelectric conversion device further includes a region control unit that controls the switching unit of each pixel based on the detection result of the detection unit, The region control unit causes the second information to be output from the counting units of the detection pixel and adjacent pixels adjacent to the detection pixel. The photoelectric conversion device according to claim 1 or 2, characterized by the above.

4. The region control unit controls the switching unit of the detection pixel, causes the second information to be output from the counting unit of the detection pixel, and among non-detection pixels that are pixels not extracted by the detection unit, the non-detection pixels located within a predetermined distance from the detection pixel are specified as the adjacent pixels, and the switching unit of the adjacent pixels is controlled to also output the second information from the counting unit of the adjacent pixels. The photoelectric conversion device according to claim 3, characterized by the above.

5. The region control unit specifies non-detection pixels surrounding the periphery of one detection pixel as the adjacent pixels. The photoelectric conversion device according to claim 4, characterized by the above.

6. The plurality of pixels are arranged on an XY coordinate composed of an X axis and a Y axis orthogonal to each other, Among the plurality of adjacent pixels surrounding the periphery of one detection pixel, at least three adjacent pixels are arranged along the X axis direction, and at least three adjacent pixels are arranged along the Y axis direction to form a rectangular shape. The photoelectric conversion device according to claim 5, characterized by the above.

7. The region control unit specifies non-detection pixels included in a region surrounding a portion where the detection pixels are concentrated as the adjacent pixels. The photoelectric conversion device according to claim 4, characterized in that...

8. The area control unit makes the number of bits of the second information output from each of the counting units different between the detected pixels extracted by the detection unit and the non-detected pixels that are pixels not extracted by the detection unit. The photoelectric conversion device according to claim 3, characterized in that...

9. When the area control unit outputs the second information from the counting unit of the detected pixels, it outputs the remaining bit information excluding the lower bit information from the second information. The photoelectric conversion device according to claim 8, characterized in that...

10. When the area control unit outputs the second information from the counting unit of the non-detected pixels, it outputs the remaining bit information excluding the first information from the second information. The photoelectric conversion device according to claim 8, characterized in that...

11. The area control unit controls the exposure period of the photoelectric conversion unit according to the number of detected pixels. The photoelectric conversion device according to claim 3, characterized in that...

12. It further includes an exposure control unit that controls the exposure of each pixel for each frame, Each of the plurality of pixels has an edge trigger circuit that detects a change in the level of a signal indicating the first information, When the number of detected pixels is equal to or more than a predetermined reference number of pixels based on the detection result by the edge trigger circuit, the exposure control unit stops the exposure of all the pixels in the target frame, The area control unit controls the switching unit of the detected pixels in the target frame where the exposure is stopped midway, causes the counting unit of the detected pixels to output the second information, and shifts to the next frame. The photoelectric conversion device according to claim 3, characterized in that...

13. The second information includes information of all bits among the predetermined number of bits. The photoelectric conversion device according to claim 1 or 2, characterized in that...

14. A photoelectric conversion device according to claim 1 or 2, And a signal processing device that processes a signal output from the photoelectric conversion device A photodetection system characterized by comprising.

15. The signal processing device generates a distance image representing distance information to an object based on the signal. The photodetection system according to claim 14, characterized in that...

16. A moving body, A photoelectric conversion device according to claim 1 or 2, Distance information acquisition means for acquiring distance information to an object from a parallax image based on a signal output from the photoelectric conversion device, Control means for controlling the moving body based on the distance information A moving body characterized by comprising the same.

Images