Photoelectric conversion device

Abstract

A photoelectric conversion device according to the present invention has: a plurality of photoelectric conversion elements; an acquisition unit that acquires a microframe formed by a one-bit signal on the basis of incident light of each of the plurality of photoelectric conversion elements; and a combining unit that combines the plurality of microframes, thereby generating a subframe formed by the multi-bit signal. The plurality of photoelectric conversion elements includes a first photoelectric conversion element and a second photoelectric conversion element. During an acquisition period of one microframe, a first exposure period in which a one-bit signal is generated based on incident light at the first photoelectric conversion element and a second exposure period in which a one-bit signal is generated based on incident light at the second photoelectric conversion element are different.

Description

Technical Field

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

[0002] Patent document 1 discloses a distance measuring device that measures the distance to an object by emitting light from a light source and receiving light including reflected light from the object by a light receiving element. In the distance measuring device of patent document 1, a single photon avalanche diode (SPAD) element that multiplies electrons generated by photoelectric conversion to obtain a signal is used as a light receiving element. Patent document 1 discloses a technology that repeatedly performs measurement while changing a gating period for detecting photons in the SPAD element.

[0003] [Citation List]

[0004] [Patent Document]

[0005] PTL 1: U.S. Patent Application Publication No. 2017 / 0052065 Summary of the invention

[0006] [Technical issues]

[0007] There is a trade-off relationship between distance resolution and frame rate in the distance measurement technology disclosed in Patent Document 1. However, in order to improve the distance measurement performance, it may be necessary to ensure appropriate distance resolution and increase the frame rate.

[0008] An object of the present invention is to provide a photoelectric conversion device having an improved frame rate while ensuring appropriate distance resolution.

[0009] [Solution to the problem]

[0010] According to one disclosure of the present specification, a photoelectric conversion device is provided, the photoelectric conversion device comprising: a plurality of photoelectric conversion elements; an acquisition unit configured to acquire a microframe consisting of a single-bit signal based on light incident on each of the plurality of photoelectric conversion elements; and a combination unit configured to combine the plurality of microframes to generate a subframe consisting of a multi-bit signal. The plurality of photoelectric conversion elements include a first photoelectric conversion element and a second photoelectric conversion element. During a period of acquiring one microframe, a first exposure period for generating a single-bit signal based on light incident on the first photoelectric conversion element is different from a second exposure period for generating a single-bit signal based on light incident on the second photoelectric conversion element.

[0011] [Beneficial effects of the present invention]

[0012] According to the present invention, there is provided a photoelectric conversion device having an improved frame rate while ensuring appropriate distance resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] [ Figure 1 ]

[0014] Figure 1 is a hardware block diagram illustrating a schematic configuration example of the distance measuring device according to the first embodiment.

[0015] [ Figure 2 ]

[0016] Figure 2 is a schematic diagram illustrating the overall configuration of a photoelectric conversion apparatus according to a first embodiment.

[0017] [ Figure 3 ]

[0018] Figure 3 is a schematic block diagram illustrating a configuration example of a sensor substrate according to the first embodiment.

[0019] [ Figure 4 ]

[0020] Figure 4 is a schematic block diagram illustrating a configuration example of a circuit substrate according to the first embodiment.

[0021] [ Figure 5 ]

[0022] Figure 5 is a schematic block diagram illustrating a configuration example of one pixel of a photoelectric conversion unit and a pixel signal processing unit according to the first embodiment.

[0023] [ Fig. 6A ]

[0024] Fig. 6A is a diagram for explaining the operation of the avalanche photodiode according to the first embodiment.

[0025] [ Figure 6B ]

[0026] Figure 6B is a diagram for explaining the operation of the avalanche photodiode according to the first embodiment.

[0027] [ Figure 6C ]

[0028] Figure 6C is a diagram for explaining the operation of the avalanche photodiode according to the first embodiment.

[0029] [ Figure 7 ]

[0030] Figure 7 is a functional block diagram illustrating a schematic configuration example of a distance measuring device according to the first embodiment.

[0031] [ Figure 8 ]

[0032] Figure 8 is a schematic diagram for explaining a ranging frame, a subframe, and a microframe according to the first embodiment.

[0033] [ Fig. 9 ]

[0034] Fig. 9 : is a flowchart illustrating the operation of the range image generation device according to the first embodiment in one range measurement frame period.

[0035] [ Fig. 10A ]

[0036] Fig. 10A is a schematic diagram of a pixel array according to the first embodiment.

[0037] [ Fig. 10B ]

[0038] Fig. 10B is a driving timing chart according to the first embodiment.

[0039] [ Fig.11A ]

[0040] Fig.11A is a schematic diagram of a pixel array according to the second embodiment.

[0041] [ Fig. 11B ]

[0042] Fig. 11B is a driving timing chart according to the second embodiment.

[0043] [ Fig. 12A ]

[0044] Fig. 12A is a schematic diagram of a pixel array according to the third embodiment.

[0045] [ Fig. 12B ]

[0046] Fig. 12B is a driving timing chart according to the third embodiment.

[0047] [ Fig.13 ]

[0048] Fig.13 is a schematic block diagram of a pixel according to the fourth embodiment.

[0049] [ Fig.14 ]

[0050] Fig.14 is a driving timing chart according to the fourth embodiment.

[0051] [ Fig.15 ]

[0052] Fig.15 is a functional block diagram illustrating a schematic configuration example of a distance measuring device according to the fifth embodiment.

[0053] [ Fig.16 ]

[0054] Fig.16 is a schematic diagram illustrating an example of external light mapping according to the fifth embodiment.

[0055] [ Fig.17A ]

[0056] Fig.17A is a schematic diagram of an apparatus according to a sixth embodiment.

[0057] [ Fig. 17B ]

[0058] Fig. 17B is a schematic diagram of an apparatus according to a sixth embodiment. DETAILED DESCRIPTION

[0059] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The same elements or corresponding elements across multiple drawings are denoted by common reference numerals, and their description may be omitted or simplified.

[0060] [First embodiment]

[0061] Figure 1 is a hardware block diagram illustrating a schematic configuration example of the distance image generating device 30 according to the present embodiment. The distance image generating device 30 includes a light emitting device 31, a light receiving device 32, and a signal processing circuit 33. Note that the configuration of the distance image generating device 30 illustrated in the present embodiment is an example and is not limited to the illustrated configuration.

[0062] The distance image generating device 30 is a device that measures the distance to the ranging object X using a technology such as light detection and ranging (LiDAR). The distance image generating device 30 measures the distance from the distance image generating device 30 to the object X based on the time difference until the light emitted from the light emitting device 31 is reflected by the object X and received by the light receiving device 32. In addition, the distance image generating device 30 emits laser light to a predetermined ranging area including the object X and receives the reflected light through a pixel array, so that the distance can be measured two-dimensionally at multiple points. As a result, the distance image generating device 30 can generate and output a distance image.

[0063] The light received by the light receiving device 32 includes ambient light such as sunlight in addition to the reflected light from the object X. Therefore, the distance image generating device 30 performs distance measurement with the influence of ambient light reduced by measuring the incident light in each of a plurality of time periods (statistical time periods) and determining that the reflected light is incident during a time period in which the light amount is at a peak.

[0064] The light emitting device 31 is a device that emits light such as laser light to the outside of the distance image generating device 30. The signal processing circuit 33 may include a processor that performs arithmetic processing on digital signals, a memory that stores digital signals, etc. The memory may be, for example, a semiconductor memory.

[0065] The light receiving device 32 generates a pulse signal including a pulse based on the incident light. For example, the light receiving device 32 is a photoelectric conversion device including an avalanche photodiode as a photoelectric conversion element. In this case, when one photon is incident on the avalanche photodiode and generates a charge, one pulse is generated by avalanche multiplication. However, the light receiving device 32 may use a photoelectric conversion element using, for example, another photodiode.

[0066] In the present embodiment, the light receiving device 32 includes a pixel array in which a plurality of photoelectric conversion elements (pixels) are arranged to form a plurality of rows and a plurality of columns. Figures 2 to 6C The photoelectric conversion device as a specific configuration example of the light receiving device 32 is described below. The configuration example of the photoelectric conversion device to be described below is an example. The photoelectric conversion device applicable to the light receiving device 32 is not limited thereto, and any photoelectric conversion device can be used as long as the configuration described below can be realized. Figure 7 function.

[0067] Figure 2 1 is a schematic diagram illustrating the overall configuration of the photoelectric conversion device 100 according to the present embodiment. The photoelectric conversion device 100 includes a sensor substrate 11 (first substrate) and a circuit substrate 21 (second substrate) stacked on each other. The sensor substrate 11 and the circuit substrate 21 are electrically connected to each other. The sensor substrate 11 has a pixel area 12 in which a plurality of pixels 101 are arranged to form a plurality of rows and columns. The circuit substrate 21 includes a first circuit area 22 and a second circuit area 23 arranged on the periphery of the first circuit area 22, in which a plurality of pixel signal processing units 103 are arranged to form a plurality of rows and columns. The second circuit area 23 may include a circuit for controlling the plurality of pixel signal processing units 103, etc. The sensor substrate 11 has a light incident surface for receiving incident light and a connection surface facing the light incident surface. The sensor substrate 11 is connected to the circuit substrate 21 on the connection surface side. That is, the photoelectric conversion device 100 is a so-called back-illuminated type.

[0068] In this specification, a "plan view" refers to a view from a direction perpendicular to a surface opposite to a light incident surface. In addition, a cross section refers to a surface in a direction perpendicular to a surface on the opposite side of the light incident surface of the sensor substrate 11. Note that in a microscopic view, the light incident surface may be a rough surface, but in this case, in a macroscopic view, the plan view is defined based on the light incident surface.

[0069] Hereinafter, the sensor substrate 11 and the circuit substrate 21 will be described as sliced ​​chips, but the sensor substrate 11 and the circuit substrate 21 are not limited to chips. For example, the sensor substrate 11 and the circuit substrate 21 may be wafers. In addition, in the case where the sensor substrate 11 and the circuit substrate 21 are sliced ​​chips, the photoelectric conversion device 100 may be manufactured by stacking the sensor substrate 11 and the circuit substrate 21 in a wafer state and then slicing the stack, or may be manufactured by slicing the sensor substrate 11 and the circuit substrate 21 and then stacking the sliced ​​sensor substrate 11 and the sliced ​​circuit substrate 21.

[0070] Figure 3 1 is a schematic block diagram illustrating an example of the arrangement of the sensor substrate 11. In the pixel region 12, a plurality of pixels 101 are arranged to form a plurality of rows and columns. Each of the plurality of pixels 101 includes a photoelectric conversion unit 102 in the substrate, the photoelectric conversion unit 102 including an avalanche photodiode (hereinafter referred to as APD) as a photoelectric conversion element.

[0071] The conductivity type of the charge used as the signal charge among the charge pairs generated in the APD is referred to as the first conductivity type. The first conductivity type refers to a conductivity type in which the charge having the same polarity as the signal charge is the main carrier. In addition, the conductivity type opposite to the first conductivity type (that is, the conductivity type in which the charge having a polarity different from that of the signal charge is the main carrier) is referred to as the second conductivity type. In the APD to be described below, the anode of the APD has a fixed potential, and a signal is extracted from the cathode of the APD. Therefore, the semiconductor region of the first conductivity type is an N-type semiconductor region, and the semiconductor region of the second conductivity type is a P-type semiconductor region. Note that the cathode of the APD may have a fixed potential, and a signal may be extracted from the anode of the APD. In this case, the semiconductor region of the first conductivity type is a P-type semiconductor region, and the semiconductor region of the second conductivity type is an N-type semiconductor region. In addition, the case in which one node of the APD has a fixed potential will be described below, but the potentials of the two nodes of the APD may be different.

[0072] Figure 4 2 is a schematic block diagram illustrating a configuration example of the circuit substrate 21. The circuit substrate 21 includes a first circuit region 22 in which a plurality of pixel signal processing units 103 are arranged to form a plurality of rows and a plurality of columns.

[0073] In addition, a vertical scanning circuit 110 , a horizontal scanning circuit 111 , a readout circuit 112 , a pixel output signal line 113 , an output circuit 114 , and a control signal generating unit 115 are arranged on the circuit substrate 21 . Figure 3 The plurality of photoelectric conversion units 102 and Figure 4 The plurality of pixel signal processing units 103 illustrated in FIG. 1 are electrically connected via connection wirings provided for the respective pixels 101 .

[0074] The control signal generating unit 115 is a control circuit that generates a control signal for driving the vertical scanning circuit 110, the horizontal scanning circuit 111, and the readout circuit 112 and supplies the control signal to each unit. As a result, the control signal generating unit 115 controls the driving timing and the like for each unit.

[0075] The vertical scanning circuit 110 supplies a control signal to each of the plurality of pixel signal processing units 103 based on the control signal supplied from the control signal generating unit 115. The vertical scanning circuit 110 supplies a control signal to each pixel signal processing unit 103 for each row via a drive line provided for each row of the first circuit area 22. As will be described below, a plurality of drive lines may be provided for each row. As the vertical scanning circuit 110, a logic circuit such as a shift register or an address decoder may be used. As a result, the vertical scanning circuit 110 selects a row from which a signal is output from the pixel signal processing unit 103.

[0076] A signal output from the photoelectric conversion unit 102 of the pixel 101 is processed by a pixel signal processing unit 103. The pixel signal processing unit 103 counts the number of pulses output from the APD included in the photoelectric conversion unit 102 to acquire and hold a digital signal having a plurality of bits.

[0077] It is not required to provide one pixel signal processing unit 103 for each pixel 101. For example, one pixel signal processing unit 103 may be shared by a plurality of pixels 101. In this case, the pixel signal processing unit 103 sequentially processes signals output from the respective photoelectric conversion units 102, thereby providing a signal processing function for each pixel 101.

[0078] The horizontal scanning circuit 111 supplies a control signal to the readout circuit 112 based on the control signal supplied from the control signal generating unit 115. The pixel signal processing unit 103 is connected to the readout circuit 112 via a pixel output signal line 113 provided for each column of the first circuit area 22. The pixel output signal line 113 for one column is shared by a plurality of pixel signal processing units 103 in the corresponding column. The pixel output signal line 113 includes a plurality of wirings, and has at least a function of outputting a digital signal from each pixel signal processing unit 103 to the readout circuit 112 and a function of supplying a control signal for selecting a column to output a signal to the pixel signal processing unit 103. The readout circuit 112 outputs a signal to a storage unit or a signal processing unit outside the photoelectric conversion device 100 via an output circuit 114 based on the control signal supplied from the control signal generating unit 115.

[0079] The photoelectric conversion units 102 in the pixel area 12 may be arranged one-dimensionally. In addition, it is not necessary to provide one of the functions of the pixel signal processing unit 103 for each pixel 101. For example, one pixel signal processing unit 103 may be shared by a plurality of pixels 101. In this case, the pixel signal processing unit 103 sequentially processes the signals output from the respective photoelectric conversion units 102, thereby providing a signal processing function for each pixel 101.

[0080] like Figure 3 and Figure 4 , a first circuit region 22 in which a plurality of pixel signal processing units 103 are arranged is arranged in a region overlapping with the pixel region 12 in a plan view. Thus, the vertical scanning circuit 110, the horizontal scanning circuit 111, the readout circuit 112, the output circuit 114, and the control signal generating unit 115 are arranged to overlap between the edge of the sensor substrate 11 and the edge of the pixel region 12 in a plan view. In other words, the sensor substrate 11 has the pixel region 12 and a non-pixel region arranged around the pixel region 12. In the circuit substrate 21, a second circuit region 23 (reference numeral 23 above) in which the vertical scanning circuit 110, the horizontal scanning circuit 111, the readout circuit 112, the output circuit 114, and the control signal generating unit 115 are arranged is arranged. Figure 2 Description) is arranged in an area overlapping with a non-pixel area in a plan view.

[0081] Note that the arrangement of the pixel output signal line 113, the arrangement of the readout circuit 112, and the arrangement of the output circuit 114 are not limited to Figure 3 For example, the pixel output signal line 113 may be arranged to extend in the row direction, and may be arranged to be shared by a plurality of pixel signal processing units 103 in a corresponding row. Then, the readout circuit 112 may be arranged so that the pixel output signal line 113 for each row is connected to the readout circuit 112.

[0082] Figure 5 1 is a schematic block diagram illustrating a configuration example of one pixel of the photoelectric conversion unit 102 and the pixel signal processing unit 103 according to the present embodiment. Figure 5 A more specific configuration example including the connection relationship between the photoelectric conversion unit 102 arranged in the sensor substrate 11 and the pixel signal processing unit 103 arranged in the circuit substrate 21 is schematically illustrated. Figure 5 middle, Figure 4 The driving lines between the vertical scanning circuit 110 and the pixel signal processing unit 103 in FIG. 1 are illustrated as driving lines 213 , 214 , and 215 .

[0083] The photoelectric conversion unit 102 includes an APD 201. The pixel signal processing unit 103 includes a quenching element 202, a waveform shaping unit 210, a counter circuit 211, a selection circuit 212, and a gating circuit 216. Note that the pixel signal processing unit 103 only needs to include at least one of the waveform shaping unit 210, the counter circuit 211, the selection circuit 212, and the gating circuit 216.

[0084] APD 201 generates charges according to incident light by photoelectric conversion. Voltage VL (first voltage) is supplied to the anode of APD 201. The cathode of APD 201 is connected to the first terminal of quenching element 202 and the input terminal of waveform shaping unit 210. A voltage VH (second voltage) higher than the voltage VL supplied to the anode is supplied to the cathode of APD 201. As a result, a reverse bias voltage is supplied to the anode and cathode of APD 201, so that APD 201 performs an avalanche multiplication operation. In APD 201 supplied with a reverse bias voltage, when charges are generated by incident light, the charges cause avalanche multiplication and generate an avalanche current.

[0085] The operation modes when the reverse bias voltage is supplied to the APD 201 include a Geiger mode and a linear mode. The Geiger mode is a mode in which the anode and cathode operate at a potential difference greater than the breakdown voltage, and the linear mode is a mode in which the anode and cathode operate at a potential difference close to or less than the breakdown voltage.

[0086] An APD operating in Geiger mode is called a single photon avalanche diode (SPAD). At this time, for example, the voltage VL (first voltage) is -30V, and the voltage VH (second voltage) is 1V. APD 201 can be operated in linear mode, or can be operated in Geiger mode. Because SPAD has a larger potential difference than APD in linear mode, resulting in a significant avalanche multiplication effect, SPAD is preferred.

[0087] The quenching element 202 serves as a load circuit (quenching circuit) during signal multiplication by avalanche multiplication. The quenching element 202 suppresses the voltage supplied to the APD 201 to suppress avalanche multiplication (quenching operation). In addition, the quenching element 202 returns the voltage supplied to the APD 201 to the voltage VH (recharging operation) by applying a current corresponding to the voltage drop caused by the quenching operation. For example, the quenching element 202 may be a resistance element.

[0088] The waveform shaping unit 210 shapes the potential change of the cathode of the APD 201 obtained at the time of photon detection, and outputs a pulse signal. As the waveform shaping unit 210, for example, an inverter circuit is used. Figure 5 An example in which one inverter is used as the waveform shaping unit 210 is illustrated, but a circuit in which a plurality of inverters are connected in series may be used as the waveform shaping unit 210 , or the waveform shaping unit 210 may be another circuit having a waveform shaping effect.

[0089] The gating circuit 216 is a circuit that performs gating so that the pulse signal output from the waveform shaping unit 210 is allowed to pass only in a predetermined period. During the period in which the pulse signal is allowed to pass through the gating circuit 216, photons incident on the APD 201 are counted by the counter circuit 211 of the subsequent stage. Therefore, the gating circuit 216 controls the exposure period in which signal generation based on incident light is performed in the pixel 101. The period in which the pulse signal is allowed to pass is controlled by a control signal supplied from the vertical scanning circuit 110 via the driving line 215. Figure 5 An example in which an AND circuit is used as the gating circuit 216 is shown. The pulse signal and the control signal are input to the two input terminals of the AND circuit. The AND circuit outputs its logical product to the counter circuit 211. Note that the gating circuit 216 only needs to realize gating and may have a circuit configuration other than an AND circuit. In addition, the waveform shaping unit 210 and the gating circuit 216 may be integrated by using a logic circuit such as a NAND circuit.

[0090] The counter circuit 211 counts the pulse signal output from the waveform shaping unit 210 via the gate circuit 216 and holds a digital signal indicating the count value. In addition, when a control signal is supplied from the vertical scanning circuit 110 via the drive line 213, the counter circuit 211 resets the held signal.

[0091] from Figure 4 The vertical scanning circuit 110 shown in FIG. Figure 5The drive line 214 shown in FIG. 1 supplies a control signal to the selection circuit 212. In response to the control signal, the selection circuit 212 switches between electrical connection and disconnection between the counter circuit 211 and the pixel output signal line 113. For example, the selection circuit 212 includes a buffer circuit or the like for outputting a signal corresponding to the value held in the counter circuit 211.

[0092] Note that in Figure 5 In the example of , switching between electrical connection and disconnection between the counter circuit 211 and the pixel output signal line 113 is performed in the selection circuit 212, but the method of controlling the signal output to the pixel output signal line 113 is not limited thereto. For example, a switch such as a transistor may be arranged at a node between the quenching element 202 and the APD 201, between the photoelectric conversion unit 102 and the pixel signal processing unit 103, and the signal output to the pixel output signal line 113 may be controlled by switching between electrical connection and disconnection. In addition, the signal output to the pixel output signal line 113 may be controlled by changing the value of the voltage VH or the voltage VL supplied to the photoelectric conversion unit 102 using a switch such as a transistor.

[0093] Fig. 6A , Figure 6B and Figure 6C 2 is a diagram for explaining the operation of the APD 201 according to the present embodiment. Fig. 6A The diagram is from Figure 5 Schematic diagram of the APD 201, quenching element 202 and waveform shaping unit 210 extracted. Fig. 6A As shown in FIG. 1 , the connection node between the input terminal of the APD 201, the quenching element 202 and the waveform shaping unit 210 is the node A. Fig. 6A As shown in FIG. 1 , the output side of the waveform shaping unit 210 is node B.

[0094] Figure 6B It's a picture. Fig. 6A A graph showing the time variation of the potential of node A. Figure 6C It's a picture. Fig. 6A During the period from time t0 to time t1, voltage VH-VL is applied to Fig. 6AAPD 201. When a photon is incident on APD 201 at time t1, avalanche multiplication occurs in APD 201. As a result, avalanche current flows through quenching element 202, and the potential of node A drops. Thereafter, the amount of potential drop further increases, and the voltage applied to APD 201 gradually decreases. Then, at time t2, avalanche multiplication in APD 201 stops. As a result, the voltage level of node A does not drop below a certain fixed value. Thereafter, during the period from time t2 to time t3, a current that compensates for the voltage drop flows from the node of voltage VH into node A, and node A stabilizes at its original potential at time t3.

[0095] In the above process, the potential of node B becomes high level during the period when the potential of node A is lower than a certain threshold. In this way, the waveform of the potential drop of node A caused by the incidence of photons is shaped by the waveform shaping unit 210 and output to node B as a pulse.

[0096] Next, the overall configuration and operation of the distance image generating device 30 will be described in more detail. Figure 7 : is a functional block diagram illustrating a schematic configuration example of the distance image generating device 30 according to the present embodiment. Figure 7 Picture shows Figure 1 A more detailed configuration of the light emitting device 31, the light receiving device 32, and the signal processing circuit 33 described in FIG.

[0097] The light emitting device 31 includes a pulse light source 311 and a light source control unit 312. The pulse light source 311 is a light source such as a semiconductor laser device that emits pulse light in the entire distance measurement area. The pulse light source 311 can be a surface light source such as a surface emitting laser. The light source control unit 312 is a control circuit that controls the light emission timing of the pulse light source 311.

[0098] The light receiving device 32 includes an imaging unit 321, a strobe pulse generating unit 322, a microframe reading unit 323, a microframe adding unit 324, an addition count control unit 325, and a subframe output unit 326. As described above, the imaging unit 321 may be a photoelectric conversion device including a pixel array in which pixel circuits each including the APD 201 are two-dimensionally arranged. As a result, the distance image generating device 30 can acquire a two-dimensional distance image.

[0099] The strobe pulse generating unit 322 is a control circuit that outputs a control signal for controlling the driving timing of the imaging unit 321. In addition, the strobe pulse generating unit 322 controls the pulse light source 311 and the imaging unit 321 to be synchronized with each other by sending and receiving control signals to and from the light source control unit 312. As a result, an image can be captured while controlling the time difference from the time when the pulse light source 311 emits light to the time when the imaging unit 321 receives light. In the present embodiment, the strobe pulse generating unit 322 drives the imaging unit 321 in a global strobe manner. Global strobe driving is a driving method in which incident light is simultaneously detected in some pixels (pixel groups) in the imaging unit 321 during the same exposure period based on the time when the pulse light is emitted from the pulse light source 311. In the global strobe driving of the present embodiment, incident light is repeatedly detected while sequentially shifting the batch exposure timing. As a result, the pixels of the imaging unit 321 simultaneously generate a one-bit signal indicating whether there is an incident photon during each of a plurality of exposure periods.

[0100] The global gate drive is realized by inputting a high-level signal to the input terminal of the gate circuit 216 of the plurality of pixels 101 during the gate period based on the control signal from the gate pulse generation unit 322. Note that, in the process to be described below, one group of the plurality of pixels 101 detects incident light during the same exposure period, and another group of the plurality of pixels 101 detects incident light during an exposure period different from the period. Such a driving method is also included in the global gate drive.

[0101] The microframe reading unit 323, the microframe adding unit 324, and the addition count control unit 325 are signal processing circuits that read a single-bit signal constituting a microframe from the imaging unit 321 and perform predetermined signal processing. Fig. 9 The operation of these units is described in detail. The subframe output unit 326 is an interface that outputs a signal from the optical receiving device 32 to the signal processing circuit 33 according to a predetermined standard. The subframe output unit 326 transfers a signal from a memory in the optical receiving device 32 to a memory in the signal processing circuit 33. The functions of these units can be described by Figure 5 The counter circuit 211, the selection circuit 212 and the gating circuit 216 in Figure 4 It is implemented by the readout circuit 112 and output circuit 114 in the embodiment.

[0102] The signal processing circuit 33 includes a subframe group storage unit 331 and a distance image generation unit 332. The signal processing circuit 33 is a computer including a processor operating as the distance image generation unit 332, a memory operating as the subframe group storage unit 331, and the like. Fig. 9 To describe the operation of these units.

[0103] Next, before describing the driving method of this embodiment, reference will be made to Figure 8 To describe the configuration of ranging frames, subframes, and microframes. Figure 8 An acquisition period of a ranging frame corresponding to a range image, a subframe for generating the ranging frame, and a microframe for generating the subframe are schematically illustrated by arranging blocks in a horizontal direction. Figure 8 The horizontal direction in indicates the passage of time, and one block indicates an acquisition period of one ranging frame, subframe, or microframe.

[0104] The ranging frame F1 corresponds to one distance image. That is, the ranging frame F1 has information corresponding to the distance to the object X calculated from the time difference from light emission to light reception for each of a plurality of pixels. In the present embodiment, it is assumed that the distance image is acquired as a moving image, and acquisition of one ranging frame F1 is repeatedly performed every time one ranging frame period T1 passes.

[0105] One ranging frame F1 is generated from a plurality of sub-frames F2. One ranging frame period T1 includes a plurality of sub-frame periods T2. Every time one sub-frame period T2 passes, one sub-frame F2 is repeatedly acquired. The sub-frame F2 is composed of a multi-bit signal corresponding to the amount of light incident in the sub-frame period T2.

[0106] One subframe F2 is generated from a plurality of microframes F3. One subframe period T2 includes a plurality of microframe periods T3. One microframe F3 is repeatedly acquired whenever one microframe period T3 passes. The microframe F3 includes a one-bit signal indicating whether light incident on the photoelectric conversion element exists or does not exist during the microframe period T3. A subframe F2 of a multi-bit signal is generated by adding and combining a plurality of microframes of a one-bit signal. As a result, one subframe F2 may include a multi-bit signal corresponding to the number of microframes in which incident light is detected within the subframe period T2.

[0107] In this way, a plurality of subframes F2 that are different from each other in the incident light acquisition period are acquired. The signal acquisition time can be associated with the distance from the distance image generation device to the distance measurement object. Then, the signal acquisition time at which the signal value is the largest can be determined from the distribution of the signal values ​​and signal acquisition times of the plurality of subframes F2. Since it is estimated that the reflected light is incident on the imaging unit 321 at the time when the signal value is the largest, the distance can be calculated by converting the signal acquisition time at which the signal value is the largest into the distance to the object X. In addition, a distance image can be generated by calculating the distance for each pixel and acquiring a two-dimensional distribution of the distance.

[0108] like Figure 8 As shown in FIG. 1 , the length of the ranging frame period T1 required to acquire one ranging frame F1 depends on the number of subframes F2. Since the number of subframes F2 is a parameter corresponding to the number of ranging points, there is a trade-off relationship between the range resolution and the frame rate.

[0109] Fig. 9 The method of driving the distance image generating device in one distance measurement frame period T1 is illustrated. Fig. 9 The driving method of this embodiment is described with reference to the flowchart of FIG.

[0110] exist Fig. 9 In the flowchart shown in FIG. , the processing instructions from “start” to “end” are in Figure 8 The processing performed during the ranging frame period T1 of acquiring one ranging frame F1. One round of processing in the loop from step S11 to step S15 indicates that Figure 8 The processing performed during the subframe period T2 of acquiring one subframe F2. One round of processing in the loop from step S11 to step S13 indicates that Figure 8 The processing performed in the microframe period T3 of acquiring one microframe F3.

[0111] In step S11, the light source control unit 312 controls the pulse light source 311 to emit pulse light in a predetermined distance measurement area. In synchronization with this, the gate pulse generation unit 322 controls the imaging unit 321 to start detection of incident light by global gate driving.

[0112] In step S12, whenever a microframe period passes, the microframe reading unit 323 reads a microframe from the imaging unit 321. The read microframe is held in the memory of the microframe adding unit 324. The memory has a storage capacity capable of holding multiple bits of data for each pixel. Whenever a microframe is read, the microframe adding unit 324 sequentially adds the value of the microframe to the value held in the memory. As a result, the microframe adding unit 324 adds a plurality of microframes within a subframe period to generate a subframe. The number of additions in the microframe adding unit 324 is controlled by the addition count control unit 325. In order to perform this control, the addition count control unit 325 holds information about a preset number of additions. As described above, the microframe reading unit 323 serves as an acquisition unit that acquires a microframe consisting of a one-bit signal based on light incident on the photoelectric conversion element. In addition, the microframe adding unit 324 serves as a combination unit that combines a plurality of microframes acquired during different periods. For example, when the number of additions is 64 times, a signal of a subframe having 6-bit gradation can be generated by combining 64 microframes.

[0113] In step S13, the microframe adding unit 324 determines whether the addition of the preset number of microframes has been completed. When the addition of the set number of microframes has not been completed ("No" in step S13), the process proceeds to step S11, and the next microframe is read. When the addition of the set number of microframes is completed ("Yes" in step S13), the process proceeds to step S14.

[0114] In step S14, the subframe output unit 326 reads the subframe for which addition has been completed from the memory of the microframe addition unit 324, and outputs the subframe to the subframe group storage unit 331. The subframe group storage unit 331 stores the subframe output from the subframe output unit 326. The subframe group storage unit 331 is configured to be able to store a plurality of subframes for generating one ranging frame individually for each subframe period.

[0115] In step S15, the signal processing circuit 33 determines whether the subframe group storage unit 331 has completed the acquisition of the subframe corresponding to the number of predetermined subframes (that is, the number of ranging points). When the acquisition of the subframe corresponding to the number of ranging points has not been completed ("No" in step S15), the processing proceeds to step S11, and a plurality of microframes are acquired again and added to read the next subframe. In this case, similar processing is performed by offsetting the start time of the global gating drive relative to the light emission time (gating offset) by one subframe period. When the acquisition of the subframe corresponding to the number of ranging points has been completed ("Yes" in step S15), the processing proceeds to step S16. The subframe corresponding to the number of ranging points is acquired by a loop from step S11 to step S15.

[0116] In step S16, the distance image generation unit 332 obtains a plurality of subframes within one ranging frame period from the subframe group storage unit 331. The distance image generation unit 332 calculates the distance corresponding to the subframe having the maximum signal value for each pixel, thereby generating a distance image indicating a two-dimensional distribution of the distance. Then, the distance image generation unit 332 outputs the distance image to a device outside the signal processing circuit 33. For example, the distance image can be used to detect the environment around the vehicle. Note that the distance image generation unit 332 can store the distance image in a memory inside the distance image generation device.

[0117] In the present embodiment, the plurality of pixels in the imaging unit 321 are divided into four pixel groups. Thus, the pixel groups differ from each other in the exposure period for reading the microframe (corresponding to Fig. 9 Step S11 in (refer to Fig. 10A and Fig. 10B A specific example thereof will be described. Fig. 10A is a schematic diagram illustrating the arrangement of pixel groups in a pixel array according to the present embodiment, and Fig. 10B is a driving timing chart illustrating the timing of the gate pulse according to the present embodiment.

[0118] The pixel array according to this embodiment includes a first pixel group 327A ( Fig. 10A "A" in the figure), the second pixel group 327B ( Fig. 10A "B" in the figure), the third pixel group 327C ( Fig. 10A"C" in the figure) and the fourth pixel group 327D ( Fig. 10A ). Fig. 10A As illustrated in FIG. 1 , the first pixel group 327A, the second pixel group 327B, the third pixel group 327C, and the fourth pixel group 327D form a two-dimensional repeating array with four pixels as one block.

[0119] Fig. 10B The "light emission" in FIG. 3 indicates the timing of light emission by the pulse light source 311. Fig. 10B As shown in FIG. 1 , the pulse light source 311 emits light at a constant cycle according to the control of the light source control unit 312. The cycle corresponds to the length of one microframe period for acquiring one microframe. Fig. 10B The "P" in G_A ” to “P G_D " indicates the input timing of various types of strobe pulses input from the strobe pulse generating unit 322 to the imaging unit 321. " G_A ”, “P G_B ”, “P G_C ” and “P G_D ” indicate different strobe pulses for controlling the first pixel group 327A, the second pixel group 327B, the third pixel group 327C, and the fourth pixel group 327D, respectively. The strobe pulses synchronized with the light emission timing L01 and corresponding to the first pixel group 327A, the second pixel group 327B, the third pixel group 327C, and the fourth pixel group 327D are strobe pulses G01, G02, G03, and G04, respectively. The strobe pulses G01, G02, G03, and G04 become high level after a predetermined time has passed from the light emission of the pulse light source 311, but the time periods during which the strobe pulses G01, G02, G03, and G04 become high level are different from each other within one microframe period. In other words, the strobe pulses G01, G02, G03, and G04 become high level at the time of the first time, the second time, the third time, and the fourth time, which are different from each other, from the light emission of the pulse light source 311. The first time to the fourth time are all shorter than the length of the microframe period.

[0120] In this way, by setting the timing of the strobe pulses G01, G02, G03 and G04 differently, the exposure time of the first pixel group 327A, the second pixel group 327B, the third pixel group 327C and the fourth pixel group 327D can be different. Therefore, four types of distance measurement points can be measured within one microframe period.

[0121] As described above, a subframe is generated by adding a plurality of microframes. That is, the first pixel group 327A, the second pixel group 327B, the third pixel group 327C and the fourth pixel group 327D output signals for generating subframes at different ranging points. When generating a subframe, the timing of the gating pulse at the beginning of the next subframe period for the first pixel group 327A is shifted by a predetermined time interval from the timing of the gating pulse in the current subframe period. In addition, for the second pixel group 327B, the third pixel group 327C and the fourth pixel group 327D, the gating movement is performed similarly. By such a gating movement, the predetermined period corresponding to each subframe period can be set as the exposure period.

[0122] In this way, by making the exposure time in each of the plurality of pixel groups different and performing the strobe movement in each subframe period for each of the plurality of pixel groups, the number of strobe movements required to measure the required number of distance measurement points is reduced. As a result, the total period of the plurality of subframes, that is, the frame period ( Figure 8 The length of T1 in is shortened. Therefore, the frame rate can be increased without reducing the number of distance measurement points (distance resolution). As described above, according to this embodiment, a photoelectric conversion device that increases the frame rate while ensuring appropriate distance resolution is provided.

[0123] In the present embodiment, the number of pixel group types is set to four, but the number of pixel group types may be at least two, and even if the number of pixel group types is not four, the frame rate improvement effect can be obtained. In addition, the number of photoelectric conversion elements included in one pixel group may be at least one. That is, for two photoelectric conversion elements (a first photoelectric conversion element and a second photoelectric conversion element), if the first exposure period of the first photoelectric conversion element and the second exposure period of the second photoelectric conversion element are different from each other in one microframe period, the above-mentioned effect can be obtained. In addition, the arrangement of the pixel groups is not limited to Fig. 10A The arrangement shown in the figure can be changed appropriately.

[0124] Note that in this embodiment, although the frame rate improvement effect can be obtained by arranging a plurality of pixel groups, the in-plane resolution of the ranging image may be reduced. Therefore, a method of reducing the influence on the in-plane resolution by supplementing pixels with missing information in the ranging image with surrounding pixels may be further applied.

[0125] [Second embodiment]

[0126] In this embodiment, another example of the arrangement of the pixel groups and the timing of the strobe pulses described in the first embodiment will be described. The description of the elements common to the first embodiment may be appropriately omitted or simplified.

[0127] Fig.11Ais a schematic diagram illustrating the arrangement of pixel groups in a pixel array according to the present embodiment, and Fig. 11B is a driving timing chart illustrating the timing of the gate pulse according to the present embodiment.

[0128] The pixel array according to this embodiment includes a first pixel group 328A ( Fig.11A "A" in the figure), the second pixel group 328B ( Fig.11A "B" in the figure), the third pixel group 328C ( Fig.11A "C" in the figure) and the fourth pixel group 328D ( Fig.11A ”D” in the figure). The first pixel group 328A and the second pixel group 328B (first photoelectric conversion element) are configured to be sensitive to light having a first wavelength. The third pixel group 328C and the fourth pixel group 328D (second photoelectric conversion element) are configured to be sensitive to light having a second wavelength different from the first wavelength. More specifically, a first color filter that transmits light having a first wavelength is disposed in the first pixel group 328A and the second pixel group 328B, and a second color filter that transmits light having a second wavelength is disposed in the third pixel group 328C and the fourth pixel group 328D. The ranges of both the first wavelength and the second wavelength in this embodiment may be, for example, in the infrared region.

[0129] The pulse light source 311 of the present embodiment is configured to be capable of separately emitting light having a first wavelength and light having a second wavelength at different periods. Fig. 11B “Light emission (first wavelength)” in indicates the timing at which light having the first wavelength is emitted by the pulse light source 311. Fig. 11B The "light emission (second wavelength)" in FIG. 1 indicates the timing of emitting light having the second wavelength by the pulse light source 311. Fig. 11B As shown in FIG, the light having the first wavelength and the light having the second wavelength are different from each other in the length of the light emission period. Fig. 11B In the example, a length of a light emission period of light having the second wavelength is twice a length of a light emission period of light having the first wavelength.

[0130] For the first pixel group 328A and the second pixel group 328B, at the timing synchronized with the light emission timing L02 of the light having the first wavelength, the strobe pulses G05 and G06 are input. For the third pixel group 328C and the fourth pixel group 328D, at the timing delayed from the light emission timing L03 of the light having the second wavelength by the time corresponding to one emission cycle of the light having the first wavelength, the strobe pulses G07 and G08 are input. Therefore, the microframe acquisition cycle for the first pixel group 328A and the second pixel group 328B is different from the microframe acquisition cycle for the third pixel group 328C and the fourth pixel group 328D. With such a setting, the first pixel group 328A and the second pixel group 328B are used as pixel groups for measuring short distances (first distance range), and the third pixel group 328C and the fourth pixel group 328D are used as pixel groups for measuring long distances (second distance range). As a result, a plurality of different ranging areas can be measured within the same subframe period. In addition, generally, in a method of repeatedly acquiring microframes each containing one bit of signal and adding them, the distance measurement area is limited by the period of repeated light emission pulses, but in the method of this embodiment, signals at both short distances and long distances can be acquired, thereby making it possible to measure distances within a wide range.

[0131] As described above, according to the present embodiment, the same effects as those of the first embodiment can be obtained, and a photoelectric conversion device capable of simultaneously acquiring a plurality of different ranging areas without reducing the frame rate is provided.

[0132] Note that in the present embodiment, the bit depth of the signal of the subframe obtained from the pixel group for short-distance ranging may be different from the bit depth of the signal of the subframe obtained from the pixel group for long-distance ranging. In the case where the number of additions of the signal for short-distance ranging is 64 times, a subframe for short distance with a depth of 6 bits is obtained. In this case, since the number of emissions of light with the second wavelength is half the number of emissions of light with the first wavelength, the number of additions of the signal for long-distance ranging is at most 32 times. Therefore, the subframe for long distance has a depth of 5 bits. In this way, the bit depth can be adjusted in the case where the bit depths of the two signals are different.

[0133] In the present embodiment, the number of wavelength types of light emitted by the pulse light source 311 is two, but may be three or more. In addition, the ratio of the period of light having different wavelengths is not limited to two times, and may be appropriately set.

[0134] [Third embodiment]

[0135] In this embodiment, still another example of the arrangement of the pixel groups and the timing of the strobe pulses described in the first and second embodiments will be described. The description of the elements common to the first or second embodiment may be appropriately omitted or simplified.

[0136] Fig. 12A is a schematic diagram illustrating the arrangement of pixel groups in a pixel array according to the present embodiment, and Fig. 12B is a driving timing chart illustrating the timing of the gate pulse according to the present embodiment.

[0137] The pixel array according to this embodiment includes a first pixel group 329R ( Fig. 12A "R" in the second pixel group 329G ( Fig. 12A "G" in the third pixel group 329B ( Fig. 12A "B" in the figure) and the fourth pixel group 329Z ( Fig. 12A "Z" in ). The first pixel group 329R, the second pixel group 329G, the third pixel group 329B and the fourth pixel group 329Z are configured to be sensitive to light with different wavelengths. More specifically, a first color filter that allows red light with a wavelength of 700nm (first wavelength) to pass is deployed in the first pixel group 329R (first photoelectric conversion element). A second color filter that allows green light with a wavelength of 550nm (third wavelength) to pass is deployed in the second pixel group 329G (third photoelectric conversion element). A third color filter that allows blue light with a wavelength of 430nm (fourth wavelength) to pass is deployed in the third pixel group 329B (fourth photoelectric conversion element). A fourth color filter that allows light with an infrared wavelength of 1000nm (second wavelength) to pass is deployed in the fourth pixel group 329Z (second photoelectric conversion element).

[0138] The pulse light source 311 of the present embodiment is configured to be able to emit light having an infrared wavelength. Fig. 12B The “light emission (infrared wavelength)” in FIG. 1 indicates the timing of emitting light having an infrared wavelength by the pulse light source 311. G_Z " indicates a strobe pulse for controlling the fourth pixel group 329Z. " G_RGB ” indicates a strobe pulse for commonly controlling the first pixel group 329R, the second pixel group 329G, and the third pixel group 329B.

[0139] For the fourth pixel group 329Z, a strobe pulse G09 is input at a timing synchronized with the light emission timing L04 of light having an infrared wavelength. For the first pixel group 329R, the second pixel group 329G, and the third pixel group 329B, a strobe pulse G10 is input within a predetermined exposure period for performing imaging.

[0140] As a result, signals including information of red, green, and blue are obtained in the first pixel group 329R, the second pixel group 329G, and the third pixel group 329B, so that color images can be generated using these signals. Note that the three colors of red, green, and blue are exemplary, and a color image can be generated as long as the acquired signal includes information of multiple colors in the visible area. In addition, similar to the first and second embodiments, by inputting a strobe pulse G09 at a timing synchronized with light emission, distance information is obtained in the fourth pixel group 329Z.

[0141] In this way, according to the configuration of this embodiment, the distance measurement signal and the color image generation signal can be acquired in the same subframe period. Therefore, a photoelectric conversion device capable of acquiring a color image and a distance image while maintaining the distance resolution and the frame rate is provided.

[0142] [Fourth embodiment]

[0143] In this embodiment, an example of a configuration in which a recharge pulse for resetting the photoelectric conversion element can be further input to the pixel circuit in the configuration of the third embodiment will be described. Descriptions of elements common to the first to third embodiments may be appropriately omitted or simplified.

[0144] Fig.13 is a schematic block diagram of a pixel according to this embodiment. Fig.13 , transistor 217 is deployed as Figure 5 201 and 202. The transistor 217 is an NMOS transistor. The source of the transistor 217 is connected to the connection node between the APD 201 and the input terminal of the waveform shaping unit 210. The voltage VH is supplied to the drain of the transistor 217. The recharge pulse is input to the gate of the transistor 217 from the vertical scanning circuit 110 via the drive line 218. When the high-level recharge pulse is input to the transistor 217, the transistor 217 is turned on, and the cathode potential of the APD 201 is reset to a potential that enables avalanche multiplication. This operation is called a recharge operation.

[0145] Fig.14 is a driving timing diagram illustrating the timing of the strobe pulse and the recharge pulse according to the present embodiment. The configuration of the pixel group in the pixel array of the present embodiment is similar to that of the third embodiment. Similar to the third embodiment, the pulse light source 311 of the present embodiment is also configured to be able to emit light having an infrared wavelength. R_Z " indicates a recharge pulse for controlling the fourth pixel group 329Z. "P R_RGB ” indicates a recharging pulse for commonly controlling the first pixel group 329R, the second pixel group 329G, and the third pixel group 329B.

[0146] The recharge pulse synchronized with the light emission timing L05 and corresponding to the fourth pixel group 329Z is the recharge pulse R01. The recharge pulse synchronized with the light emission timing L05 and corresponding to the first pixel group 329R, the second pixel group 329G and the third pixel group 329B is the recharge pulse R02. The recharge pulses R01 and R02 become high level after a predetermined time has passed from the light emission of the pulse light source 311, but the periods during which the recharge pulses R01 and R02 become high level during one microframe period are different from each other.

[0147] After the recharge pulse R01 falls, the strobe pulse G11 corresponding to the fourth pixel group 329Z becomes high level. In addition, after the recharge pulse R02 falls, the strobe pulse G12 corresponding to the first pixel group 329R, the second pixel group 329G and the third pixel group 329B becomes high level.

[0148] In the first pixel group 329R, the second pixel group 329G and the third pixel group 329B, the period from the fall of the recharge pulse R02 to the fall of the strobe pulse G12 is a photon detection period for capturing a color image. That is, in the configuration of the present embodiment, by appropriately setting the timing of the recharge pulse R02 and the strobe pulse G12, the charge accumulation time when capturing a color image can be controlled. In the configuration of the third embodiment, since the strobe pulse G10 for capturing a color image is maintained at a high level, image blurring, mixing of signals from different objects, etc. may occur when the object is a moving object. However, in the configuration of the present embodiment, by appropriately setting the charge accumulation time when capturing a color image, the influence of such factors can be reduced. Therefore, according to the present embodiment, the same effect as that of the third embodiment can be obtained, and the image quality can be further improved.

[0149] [Fifth embodiment]

[0150] In this embodiment, an example of a configuration capable of further generating an external light map from microframes of a plurality of pixel groups in the configurations of the first to fourth embodiments will be described. Descriptions of elements common to the first to fourth embodiments may be appropriately omitted or simplified.

[0151] Fig.15 1 is a functional block diagram illustrating a schematic configuration example of a distance measuring device according to the present embodiment. Fig.15 In addition to Figure 7 In addition to the configuration of the present invention, a flag calculation unit 327 is also deployed in the optical receiving device 32, and a mapping generation unit 333 is also deployed in the signal processing circuit 33. Other configurations are similar to those of any one of the first embodiment to the fourth embodiment. Hereinafter, the operations of the flag calculation unit 327 and the mapping generation unit 333 of this embodiment will be described based on the configuration of the first embodiment.

[0152] The flag calculation unit 327 performs a logical operation such as a logical product on the one-bit signals for the microframe output from the plurality of pixel groups, and outputs the result as an external light flag. The external light flag is a one-bit signal indicating the presence or absence of ambient light (external light) emitted from a device other than the light emitting device 31. For example, the flag calculation unit 327 calculates the logical product of four one-bit signals output from the first pixel group 327A, the second pixel group 327B, the third pixel group 327C, and the fourth pixel group 327D, respectively. In this case, when all the logical values ​​of the four one-bit signals are "1", the logical value of the calculation result is "1". The pixel groups to be added can be selected from a plurality of pixels adjacent to each other, such as a group consisting of Fig. 10A The reference numerals in the figure represent four pixels.

[0153] The flag calculation unit 327 generates a plurality of external light flags by performing similar logic operation processing on a plurality of regions selected from the entire pixel array, respectively. The map generation unit 333 acquires the plurality of external light flags generated by the flag calculation unit 327, generates an external light map in which the logic values ​​of the external light flags are associated with the positions in the pixel array, and outputs the external light map to the outside.

[0154] Fig.16 is a schematic diagram illustrating an example of external light mapping according to the present embodiment. Fig.16 The image captured by the photoelectric conversion device mounted on the vehicle is illustrated, in which a frame with "1" is superimposed and displayed only in the area where the logic value of the external light sign is "1". Fig.16 As shown in the figure, in a blue sky area where the brightness is generally high due to the influence of sunlight, the logic value of the external light flag is "1".

[0155] Generally, in a method of measuring distance by emitting light from a light source and detecting light reflected by an object, external light such as sunlight that exists independently of the light from the light source may affect accuracy. For example, external light that is not reflected light from an object may generate an erroneous signal indicating the object.

[0156] Many external light based detection values ​​are position dependent. For example, Fig.16The area receiving external light from the blue sky illustrated in the figure is spread over a wide range in the upper part of the image. In the present embodiment, the external light flag is calculated by a logical operation of a one-bit signal output from a plurality of pixels, thereby making it possible to detect pixels where external light having a certain tendency as described above is likely to be incident. By generating an external light map using the external light flag, information indicating areas where external light is likely to be incident can be output to the outside. The external light map can be used for image processing at a subsequent stage. For example, in the case of performing a process of identifying an object in an image, by excluding areas with a logical value of "1" in the external light map from the process, there is no need to expend processing resources in areas with lower precision due to external light, thereby speeding up the process. This object recognition is suitable for, for example, autonomous driving.

[0157] In this way, according to the present embodiment, there is provided a photoelectric conversion device capable of outputting information indicating signal accuracy to the outside.

[0158] Note that in the present embodiment, logical product is used as an example of the logical operation performed in the flag calculation unit 327, but the present invention is not limited thereto, and any processing may be used as long as a value is output based on signals from a plurality of pixels. For example, the logical operation may be a logical sum.

[0159] [Sixth embodiment]

[0160] Fig.17A and Fig. 17B 80 is a block diagram of equipment related to a vehicle-mounted distance measuring device according to the present embodiment. Equipment 80 includes a distance measuring unit 803 as an example of a distance image generating device of the above-mentioned embodiment and a signal processing device (processing device) that processes a signal from the distance measuring unit 803. Equipment 80 includes a distance measuring unit 803 that measures the distance to an object and a collision determination unit 804 that determines whether there is a possibility of a collision based on the measured distance. The distance measuring unit 803 is an example of a distance information acquisition unit that obtains distance information to an object. That is, the distance information is information about the distance to an object, etc. The collision determination unit 804 can use the distance information to determine the possibility of a collision.

[0161] The equipment 80 is connected to the vehicle information acquisition device 810, and can obtain vehicle information such as vehicle speed, yaw rate, and steering angle. In addition, the equipment 80 is connected to the control ECU 820, which is a control device that outputs a control signal for generating a braking force to the vehicle based on the determination result of the collision determination unit 804. The equipment 80 is also connected to the alarm device 830, which issues an alarm to the driver based on the determination result of the collision determination unit 804. For example, when the possibility of collision is high as a result of the determination of the collision determination unit 804, the control ECU 820 performs vehicle control to avoid collision or reduce damage by braking, returning the accelerator, suppressing engine output, etc. The alarm device 830 warns the user by emitting an alarm sound, displaying an alarm message on a screen of a car navigation system, etc., or providing vibration to a seat belt or a steering wheel, etc. These devices of the equipment 80 serve as a movable body control unit that controls the operation of controlling the vehicle as described above.

[0162] In the present embodiment, ranging is performed by the equipment 80 in an area around the vehicle (eg, a front area or a rear area). Fig. 17B The equipment is illustrated when performing ranging in the area in front of the vehicle (ranging area 850). The vehicle information acquisition device 810 as a ranging control unit sends an instruction to perform ranging operation to the equipment 80 or the distance measurement unit 803. With such a configuration, the accuracy of distance measurement can be further improved.

[0163] Although an example of control for avoiding a collision with another vehicle has been described above, the embodiments are applicable to an automatic driving control for following another vehicle, an automatic driving control for not leaving a lane, and the like. Furthermore, the equipment is not limited to vehicles such as automobiles, and can be applied, for example, to movable bodies (movable devices) such as ships, airplanes, satellites, industrial robots, and consumer-use robots, and the like. In addition, the equipment can be widely applied to equipment utilizing object recognition or biometric authentication such as an intelligent transportation system (ITS), a monitoring system, and the like, without being limited to movable bodies.

[0164] [Modified Example]

[0165] The present invention is not limited to the above embodiments, and various modifications are possible. For example, an example in which some of the configurations of any one embodiment are added to other embodiments and an example in which some of the configurations of any one embodiment are replaced with some of the configurations of other embodiments are also embodiments of the present invention.

[0166] The disclosure of this specification includes the complementary set of concepts described in this specification. That is, for example, if the description "A is B" (A=B) is provided in this specification, even if the description "A is not B" (A≠B) is omitted, this specification is intended to disclose or imply "A is not B". This is because it is assumed that "A is not B" is considered when describing "A is B".

[0167] The present invention can also be implemented by the following process: a program for implementing one or more functions of the above-mentioned embodiments is supplied to a system or device via a network or storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be implemented by a circuit (e.g., ASIC) that implements one or more functions.

[0168] It is noted that the above-described embodiments are only specific examples for realizing the present invention, and the technical scope of the present invention should not be interpreted by these embodiments in a restricted manner. That is, the present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the accompanying claims are provided to disclose the scope of the present invention.

[0169] This application claims priority based on Japanese Patent Application No. 2022-142845 filed on September 8, 2022, the entire contents of which are incorporated herein by application.

[0170] [Reference Symbol List]

[0171] 321 Imaging Unit

[0172] 322 Strobe pulse generation unit

[0173] 323 micro frame reading unit

[0174] 324 microframe adding unit

Claims

1. A photoelectric conversion device, comprising: A plurality of photoelectric conversion elements; an acquisition unit configured to acquire a microframe consisting of a one-bit signal based on light incident on each of the plurality of photoelectric conversion elements; as well as a combining unit configured to combine the plurality of microframes to generate a subframe consisting of a multi-bit signal; The plurality of photoelectric conversion elements include a first photoelectric conversion element and a second photoelectric conversion element, and During a period of acquiring one microframe, a first exposure period for generating the one-bit signal based on light incident on the first photoelectric conversion element is different from a second exposure period for generating the one-bit signal based on light incident on the second photoelectric conversion element.

2. The photoelectric conversion device according to claim 1, in, The first photoelectric conversion element is sensitive to light having a first wavelength, and The second photoelectric conversion element is sensitive to light having a second wavelength, which is different from the first wavelength.

3. The photoelectric conversion device according to claim 2, wherein: A period in which the microframe is acquired based on light incident on the first photoelectric conversion element is different from a period in which the microframe is acquired based on light incident on the second photoelectric conversion element.

4. The photoelectric conversion device according to claim 2 or 3, in, A signal based on the light incident on the first photoelectric conversion element is used for distance measurement within a first distance range, and The signal based on the light incident on the second photoelectric conversion element is used for distance measurement within a second distance range, which is different from the first distance range.

5. The photoelectric conversion device according to claim 2, in, A signal based on light incident on the first photoelectric conversion element is used to generate an image, and Here, a signal based on the light incident on the second photoelectric conversion element is used for distance measurement.

6. The photoelectric conversion device according to claim 5, in, The plurality of photoelectric conversion elements further include a third photoelectric conversion element and a fourth photoelectric conversion element, and wherein the third photoelectric conversion element is sensitive to light having a third wavelength, the third wavelength being different from both the first wavelength and the second wavelength, and The fourth photoelectric conversion element is sensitive to light having a fourth wavelength, and the fourth wavelength is different from all of the first wavelength, the second wavelength, and the third wavelength.

7. The photoelectric conversion device according to claim 6, wherein Signals based on light incident on the first photoelectric conversion element, the third photoelectric conversion element, and the fourth photoelectric conversion element are used to generate a color image.

8. The photoelectric conversion device according to any one of claims 5 to 7, in, The first wavelength is a wavelength in the visible region, and Wherein, the second wavelength is a wavelength in the infrared region.

9. The photoelectric conversion device according to any one of claims 1 to 8, wherein During a period of acquiring one microframe, a time at which the first photoelectric conversion element is reset is different from a time at which the second photoelectric conversion element is reset.

10. The photoelectric conversion device according to any one of claims 1 to 9, further comprising a calculation unit configured to generate a signal by a logical operation based on the following signals: The one-bit signal based on the light incident on the first photoelectric conversion element and the one-bit signal based on the light incident on the second photoelectric conversion element.

11. The photoelectric conversion device according to claim 10, wherein The signal output by the calculation unit indicates the presence or absence of ambient light.

12. The photoelectric conversion device according to claim 10 or 11, wherein The logical operation is a logical product of the one-bit signal based on the light incident on the first photoelectric conversion element and the one-bit signal based on the light incident on the second photoelectric conversion element.

13. The photoelectric conversion device according to any one of claims 1 to 12, in, The first exposure period starts at a time when a first time has elapsed from a light emission timing of a light source, the light source being configured to emit light toward a distance measuring object, and Here, the second exposure period starts at a time when a second time has passed from the light emission timing, and the second time is different from the first time.

14. The photoelectric conversion device according to any one of claims 1 to 13, in, The photoelectric conversion element includes an avalanche photodiode, and The one-bit signal indicates whether a photon is incident on the avalanche photodiode during a period of acquiring the microframe.

15. The photoelectric conversion device according to any one of claims 1 to 14, wherein The combining unit generates the multi-bit signal by adding the values ​​of the single-bit signal each time the microframe is acquired.

16. A distance image generating device, comprising: The photoelectric conversion device according to any one of claims 1 to 15; as well as A distance image generation unit is configured to generate a distance image based on the signal generated by the photoelectric conversion device.

17. A movable body, comprising: The photoelectric conversion device according to any one of claims 1 to 15; as well as A movable body control unit is configured to control the movable body based on the distance information acquired by the photoelectric conversion device.

Images