Photoelectric conversion device and method of controlling photoelectric conversion device

Abstract

To provide a photoelectric conversion device capable of achieving a reduction in power consumption.SOLUTION: A photoelectric conversion device includes a light detection unit that includes a photoelectric conversion element, a control unit that controls the light detection unit and a light source device, and a processing unit that processes a signal indicating a detection result of incident light to the light detection unit. The control unit controls the light source device so that pulsed light is emitted from the light source device, and controls the light detection unit so as to detect light incident on the light detection unit in a time window corresponding to a certain distance. The processing unit outputs a light detection frame constituted by a 1-bit signal by calculating a logical sum of signals that are output from the light detection unit and indicate detection results, the number of the signals corresponding to a light emission number. The light emission number varies depending on distances to be measured.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion device and a method for controlling the photoelectric conversion device.

Background Art

[0002] Patent Document 1 discloses a photoelectric conversion device having a pixel structure in which crosstalk between adjacent avalanche diodes is suppressed. Further, Patent Document 1 discloses a time-gating ToF (Time-of-Flight) type distance image sensor. In time-gating ToF, the distance between the subject and the photoelectric conversion device is measured by sweeping the time position of the gate window, which is the photon detection period, and acquiring the distribution of photon count values at each time position. When driving the distance image sensor of Patent Document 1, laser pulse light is irradiated and light is detected a plurality of times in the measurement for each gate window.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the time-gating ToF technology as disclosed in Patent Document 1, reduction of power consumption associated with multiple measurements can be a problem.

[0005] An object of the present invention is to provide a photoelectric conversion device and a method for controlling the photoelectric conversion device that can reduce power consumption.

Means for Solving the Problems

[0006] According to one disclosure of the present specification, there is provided a photoelectric conversion device including a light detection unit including a photoelectric conversion element, a control unit for controlling the light detection unit and a light source device, and a processing unit for processing a signal indicating a detection result of incident light on the light detection unit. In a first measurement, the control unit controls the light source device so that first pulsed light of a first number of light emissions is emitted from the light source device, and controls the light detection unit to detect light incident on the light detection unit in a first time window corresponding to a first distance. In the first measurement, the processing unit outputs a first light detection frame composed of 1-bit signals by calculating a logical sum for a signal indicating detection results of a number corresponding to the first number of light emissions output from the light detection unit. In a second measurement, the control unit controls the light source device so that second pulsed light of a second number of light emissions different from the first number of light emissions is emitted from the light source device, and controls the light detection unit to detect light incident on the light detection unit in a second time window corresponding to a second distance different from the first distance. In the second measurement, the processing unit outputs a second light detection frame composed of 1-bit signals by calculating a logical sum for a signal indicating detection results of a number corresponding to the second number of light emissions output from the light detection unit.

[0007] According to one disclosure of the present specification, there is provided a control method for a photoelectric conversion device having a photodetection unit including a photoelectric conversion element, the method including: controlling the light source device so that first pulsed light of a first number of light emissions is emitted from the light source device; detecting light incident on the photodetection unit in a first time window corresponding to a first distance; outputting a first photodetection frame composed of 1-bit signals by calculating a logical sum for a signal indicating a number of detection results corresponding to the first number of light emissions output from the photodetection unit; controlling the light source device so that second pulsed light of a second number of light emissions different from the first number of light emissions is emitted from the light source device; detecting light incident on the photodetection unit in a second time window corresponding to a second distance different from the first distance; and outputting a second photodetection frame composed of 1-bit signals by calculating a logical sum for a signal indicating a number of detection results corresponding to the second number of light emissions output from the photodetection unit.

Effects of the Invention

[0008] According to the present invention, there are provided a photoelectric conversion device and a control method for the photoelectric conversion device capable of reducing power consumption.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same elements or corresponding elements are given common reference numerals throughout a plurality of drawings, and the description thereof may be omitted or simplified.

[0011] [First Embodiment] Prior to the description of the distance measuring device of this embodiment, an overall picture of the operation and problems of a time-gating ToF (Time of Flight) type distance measuring device will be described. FIGS. 1(a), 1(b), and 1(c) are graphs for explaining the operation and problems of a time-gating ToF type distance measuring device.

[0012] The distance measuring device repeatedly emits laser pulse light towards the subject. Then, the distance measuring device acquires time information indicating the time from the time when the laser pulse light is emitted to the time when the reflected pulse light from the subject reaches the distance measuring device. The distance measuring device acquires the distance from the distance measuring device to the subject by converting this time information into distance information. In a time-gating ToF type distance measuring device, the distance measuring device detects the reflected pulse light that has reached the distance measuring device within the period of the time window.

[0013] Figure 1(a) is a graph schematically showing the relationship between the intensity distribution of the reflected light and the time window. The horizontal axis of Figure 1(a) indicates time in arbitrary units, and the vertical axis of Figure 1(a) indicates intensity in arbitrary units. The time window W in Figure 1(a) schematically shows the detection period of photons in the distance measuring device. The intensity distribution D1 in Figure 1(a) schematically shows the intensity distribution of the reflected light incident on the distance measuring device. The distance measuring device measures the number of detection times of photons incident on the distance measuring device within the period of the time window W by sweeping the time window W in the time direction.

[0014] The distance measuring device converts the time information based on the time position of the time window W obtained as described above into measured distance information. The distance measuring device associates the time information or the measured distance with the number of photon detections and stores it as a frequency distribution. Figure 1(c) shows an example of the frequency distribution obtained in this way. The horizontal axis of Figure 1(c) indicates distance in arbitrary units, and the vertical axis of Figure 1(c) indicates the count value corresponding to the number of photon detections.

[0015] Note that the count value obtained by measuring the number of photon detections during the period of the time window W does not necessarily match the number of incident photons. In the measurement of the number of photon detections, a process of counting a 1-bit value indicating whether or not photons have entered the distance measuring device within the period of the time window W is repeatedly performed a plurality of times. In this specification, an event that photons have entered the distance measuring device is also referred to as a photon incidence event. The number of photon detections can also be read as the number of photon incidence events.

[0016] In the measurement of the incident events of photons within the time window W, the laser pulse light is emitted multiple times. The greater the number of emissions of the laser pulse light, the higher the probability of photon incidence within the time window W, that is, the higher the probability that the distance measuring device detects the incident events of photons. By sweeping the time window W, a plurality of count values including the number of detections of photons incident during the period of the first time window corresponding to the first distance (for example, C1 in FIG. 1(c)) and the number of detections of photons incident on the second time window corresponding to the second distance (for example, C2 in FIG. 1(c)) are measured. By obtaining the distance (peak position) corresponding to the maximum value of the count value from the frequency distribution thus obtained, the distance measuring device acquires the distance from the distance measuring device to the subject.

[0017] The generation of the frequency distribution is performed by sampling measurement by sweeping the period of the time window W. That is, the frequency distribution approximates the result of the convolution operation between the waveform of the time window W and the intensity distribution D2 of the reflected light from the subject in FIG. 1(a).

[0018] FIG. 1(b) is a graph showing the relationship between the distance and intensity of the emitted laser pulse light. The horizontal axis of FIG. 1(b) indicates the distance in arbitrary units, and the vertical axis of FIG. 1(b) indicates the intensity in arbitrary units. The intensity distribution D2 in FIG. 1(b) shows the relationship between the flight distance of light and the intensity of light. As shown in FIG. 1(b), the intensity of light is inversely proportional to the square of the distance. Therefore, the number of photons incident on the time window W changes according to the measurement distance. For example, the closer the measurement distance, the greater the number of photons incident on the time window W.

[0019] However, when a sufficient number of photons enter the time window W for the determination of photon incidence events, the number of photon detections (count value of photon incidence events) does not change with the increase in the number of photons. Therefore, in this case, a deviation occurs between the number of photons and the number of photon detections. More specifically, when two or more photons enter the time window W due to the emission of a single laser pulse light, there is a high possibility of a deviation between the number of photons and the number of photon detections. In the detection of photon incidence events, even when multiple photons enter, the number of photon detections is determined as one time. Therefore, the number of photon detections is underestimated with respect to the number of photons entering the time window W. In addition, the influence of the distance dependence of the intensity shown in the intensity distribution D2 is also superimposed on the frequency distribution. According to the inventor's study, in the region where the distance from the ranging device to the subject is 10 m or less, the deviation between the number of photons and the number of photon detections tends to be particularly large, and it is desirable to suppress this deviation.

[0020] When the contribution rate of the increase in the number of laser pulse light emissions to the number of photon detections is extremely low in a state where the deviation between the number of photons and the number of photon detections is large, an excess occurs in the number of laser pulse emissions, consuming extra power. In the present embodiment, this problem is solved by appropriately adjusting the number of laser pulse emissions according to the distance.

[0021] As a method different from the above time-gating ToF type ranging device, there is a dToF (Direct Time of Flight) type ranging device that directly measures the flight time of photons. In the dToF type ranging device, the detector is kept in an exposure state during the assumed flight time, and when photons enter, the time is measured to obtain the number of incident photons in each period. Thereby, the generation of the frequency distribution is performed. Compared with the dToF type ranging device, the time-gating ToF type ranging device can control the exposure time of the detector by the period of the time window W. Since the influence of external light outside the period of the time window W can be suppressed, the time-gating ToF type is a measurement method with strong resistance to external light.

[0022] Hereinafter, with reference to the drawings, the detailed configuration of the time-gating ToF type distance measuring device of the present embodiment will be described.

[0023] FIG. 2 is a block diagram showing a configuration example of the distance measuring device according to the present embodiment. The distance measuring device shown in FIG. 2 is a time-gating ToF type distance measuring device. The distance measuring device 1 includes a light source device 120, a light detection device 130, an arithmetic processing device 140, and an environment monitoring device 150. The light source device 120 includes a pulse light source 121 and a light source control unit 122. The light detection device 130 includes a light detection unit 131, a gate pulse control unit 132, a light emission control unit 133, a light detection frame setting unit 134, a light detection frame reading unit 135, a light detection frame addition unit 136, and a distance measurement frame output unit 137. The arithmetic processing device 140 includes a light emission count setting unit 141, a distance measurement frame group storage unit 142, and a distance image arithmetic unit 143.

[0024] The pulse light source 121 is a light source that generates laser pulse light, and can be, for example, a solid-state laser or a semiconductor laser. When miniaturization or power saving of the light source device 120 is required, it is desirable that the pulse light source 121 be a semiconductor laser. In this case, the semiconductor laser can be an edge emitting laser (EEL) or a surface emitting laser (SEL). When two-dimensional array or high-speed modulation is required, the surface emitting laser is preferably a vertical cavity surface emitting laser (VCSEL). In the present embodiment, since modulation of the laser pulse light is performed, it is desirable that a vertical cavity surface emitting laser be used for the pulse light source 121. The wavelength of the light output by the pulse light source 121 can be, for example, a desired wavelength among 650 nm to 1080 nm, but is not limited thereto. For example, the wavelength of the light output by the pulse light source 121 may be 1310 nm, 1550 nm, etc. used for medium- and long-distance communication.

[0025] The light source control unit 122 is a driving device that controls the light emission of the pulsed light source 121. The light source control unit 122 outputs a first control pulse, which is a driving signal for the laser pulse light, to the pulsed light source 121. The pulsed light source 121 controls light emission with reference to the first control pulse. For example, for one input of the first control pulse, the pulsed light source 121 emits laser pulse light once or multiple times. In this embodiment, it is assumed that for one input of the first control pulse, the laser pulse light is emitted once.

[0026] The light detection unit 131 is a semiconductor element that detects light. The light detection unit 131 is composed of one or more pixels. The pixel includes a photoelectric conversion element. When the light detection unit 131 has a plurality of pixels, the light detection unit 131 functions as an image sensor that detects a two-dimensional light distribution. The light detection unit 131 may include a photodiode, an avalanche photodiode, etc. as the photoelectric conversion element. The avalanche photodiode may be a SPAD (Single Photon Avalanche Diode). In this embodiment, in order to detect a weak signal at the single photon level at high speed, it is assumed that a SPAD operating in Geiger mode is used for the light detection unit 131. It is desirable that the detection wavelength of the light detection unit 131 coincides with the wavelength of the light emitted by the pulsed light source 121.

[0027] In order to perform high-precision light detection, it is desirable to perform measurement in an environment where the intensity of noise light from an external noise source 192 is low. This noise source 192 can be, for example, the sun. In order to reduce the influence of such noise light, in this embodiment, as the configuration of the distance measuring device, a time-gating ToF type that restricts the exposure time is adopted. Further, the intensity distribution of the noise light from the noise source 192 may follow the intensity distribution of blackbody radiation. In this case, in order to avoid the peak of the intensity distribution of blackbody radiation, it is desirable that the detection wavelength of the light detection unit 131 be longer than visible light. For example, the wavelength of the light emitted by the pulse light source 121 and the detection wavelength of the light detection unit 131 may be 1550 nm. Further, in order to suppress the influence of the noise light, the light detection unit 131 may have a band-pass filter. Further, the light detection unit 131 may have an imaging optical system. The imaging optical system forms an image of the reflected pulse light from the subject 191 on the light detection unit 131.

[0028] The gate pulse control unit 132 can be configured by a semiconductor integrated circuit such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). Similarly, the light emission control unit 133, the light detection frame setting unit 134, the light detection frame reading unit 135, the light detection frame addition unit 136, and the distance measurement frame output unit 137 can also be configured by a semiconductor integrated circuit such as an FPGA or an ASIC.

[0029] The gate pulse control unit 132 outputs a second control pulse for controlling the light detection operation of the light detection unit 131 to the light detection unit 131. The second control pulse is a control signal for setting the timing of the time window. The light detection unit 131 performs light detection during the period when the second control pulse is valid. The gate pulse control unit 132 is synchronized with the light source control unit 122 and indirectly controls the timing of the first control pulse. The gate pulse control unit 132 controls the time interval between the first control pulse and the second control pulse by controlling the phase of the second control pulse. That is, the gate pulse control unit 132 sets the time position of the time window in which light detection is performed. The gate pulse control unit 132 controls the first control pulse and the second control pulse with reference to the number of light emission times output by the light emission control unit 133 and the measurement distance information and measurement period information output by the light detection frame setting unit 134.

[0030] The light emission control unit 133 is an arithmetic processing circuit that outputs the number of light emission times of the light source device 120 to the gate pulse control unit 132. The light emission control unit 133 is also an interface circuit for the arithmetic processing device 140. According to the time position of the time window set by the gate pulse control unit 132, the light emission control unit 133 transmits information on the number of light emission times to the gate pulse control unit 132. The gate pulse control unit 132 monitors the number of light emission times and stops the output of the first control pulse and the second control pulse after a predetermined number of light emission times is reached. Alternatively, the light emission control unit 133 may include a counter that counts the number of pulses of the first control pulse via the gate pulse control unit 132. In this case, after the first control pulse reaches a predetermined number of light emission times, the light emission control unit 133 outputs a signal for stopping the output of the first control pulse and the second control pulse to the gate pulse control unit 132.

[0031] The optical detection frame setting unit 134 is an arithmetic processing circuit that outputs information regarding the time window to the gate pulse control unit 132. In other words, the optical detection frame setting unit 134 outputs the time position of the time window (corresponding to the measurement distance information). The optical detection frame setting unit 134 is also an interface circuit for the arithmetic processing device 140. The optical detection frame setting unit 134 outputs the period of the optical detection frame and the number of frames of the optical detection frame in each time window to the gate pulse control unit 132. The gate pulse control unit 132 determines the signal patterns of the first control pulse and the second control pulse based on the information on the number of light emission times acquired from the light emission control unit 133 and the information on the period (measurement period information) and the number of frames of the optical detection frame acquired from the optical detection frame setting unit 134. Also, the optical detection frame setting unit 134 outputs the information on the number of frames of the optical detection frame to the optical detection frame addition unit 136. The details of the optical detection frame will be described later. As described above, the gate pulse control unit 132, the light emission control unit 133, and the optical detection frame setting unit 134 function as control units for controlling the optical detection unit 131 and the light source device 120.

[0032] The optical detection frame reading unit 135 is an arithmetic processing circuit that outputs an optical detection frame based on the signal output from the optical detection unit 131. The optical detection frame is an image obtained by reading out the output signals from each pixel constituting the optical detection unit 131 and calculating the logical sum of the signals corresponding to the number of light emission times for each pixel. The signal corresponding to each pixel of the optical detection frame is a 1-bit signal.

[0033] The optical detection frame addition unit 136 is an arithmetic processing circuit that adds a predetermined number of optical detection frames output by the optical detection frame reading unit 135. More specifically, the optical detection frame addition unit 136 refers to the number of frames output from the optical detection frame setting unit 134, and acquires the optical detection frames corresponding to this number of frames from the optical detection frame reading unit 135. Then, the optical detection frame addition unit 136 adds the pixel values of the pixels at the same position among the plurality of optical detection frames, generates pixel information, and outputs it to the distance measurement frame output unit 137.

[0034] The ranging frame output unit 137 is an arithmetic processing circuit that generates a ranging frame from the pixel information output from the light detection frame addition unit 136. The ranging frame is a distribution image with the number of photon incidence events at one measured distance corresponding to the time window as the pixel value. The ranging frame output unit 137 is also an interface circuit that transfers the ranging frame from the light detection device 130 to the arithmetic processing device 140 according to a predetermined image transfer protocol. As described above, the light detection frame reading unit 135, the light detection frame addition unit 136, and the ranging frame output unit 137 function as processing units that process signals indicating the detection results of incident light on the light detection unit.

[0035] The arithmetic processing device 140 can be composed of a semiconductor integrated circuit such as an FPGA or an ASIC. That is, the functions of the light emission count setting unit 141, the ranging frame group storage unit 142, and the distance image arithmetic unit 143 can be realized by a semiconductor integrated circuit such as an FPGA or an ASIC.

[0036] The light emission count setting unit 141 is an arithmetic processing circuit that sets the number of light emission times of the laser pulse light used for distance measurement in each time window and outputs it to the light emission control unit 133. In addition, the light emission count setting unit 141 sets the number of frames of the light detection frame output in the distance measurement in each time window and outputs it to the light detection frame setting unit 134.

[0037] The details of the setting of the light emission count will be described. In the light emission count setting unit 141, the signal-to-noise ratio (SNR) of the ranging device in the detection of light is set in advance. The light emission count setting unit 141 obtains the measured distance from the time position of the time window, and based on the measured distance, sets the light emission count such that the SNR of the ranging device falls within a predetermined range.

[0038] The SNR is the value obtained by dividing the number of photons n contained in the reflected pulse light incident on the light detection unit 131 within the period of the time window by the noise. When the number of photons incident on the light detection unit 131 within the period of the time window follows a Poisson distribution, the noise caused by the variation in the incident photon number is √n.

[0039] The number of photons n is inversely proportional to the square of the distance between the subject 191 and the light detection unit 131. Also, as long as the measurement conditions do not change, the number of photons n is proportional to the emission frequency of the laser pulse light.

[0040] As factors of noise with respect to the number of photons n, in addition to the noise caused by the variation in the number of incident photons, the noise light emitted from the noise source 192 is included. When the noise source 192 is located sufficiently far from the distance measurement device compared to the distance between the subject 191 and the distance measurement device, it can be assumed that the noise light incident within the period of the time window is constant and does not depend on the distance. When there are multiple factors of noise in this way, the overall noise is calculated by the square root of the sum of the squares of each noise.

[0041] As described above, if the number of photons incident on the light detection unit 131 within the period of the time window can be defined under a certain measurement distance condition, the emission frequency of the laser pulse light can be calculated based on the measurement distance so that the SNR becomes a value within a predetermined range. The number of incident photons per emission can be calculated, for example, from the power of the laser pulse light, the beam shape of the laser pulse light, the reflectivity of the subject 191, the measurement distance between the subject 191 and the light detection unit 131, and the angular field of view of the light detection device 130. The emission frequency setting unit 141 can calculate the emission frequency based on an equation using variables such as the power of the laser pulse light, the reflectivity of the subject 191, the power of the noise light, and the measurement distance between the subject 191 and the light detection unit 131. Also, in setting the emission frequency, ray tracing may be combined with the calculation of the number of photons.

[0042] The emission frequency setting unit 141 may set the emission frequency based on an emission frequency table that stores in advance the calculated emission frequencies in the form of a look-up table. The emission frequency table includes information in which the measurement distance and the emission frequency are associated. By using the emission frequency table, it is not necessary to calculate the emission frequency when changing the setting of the distance measurement frame. Therefore, it is possible to reduce the calculation load, and the measurement operation can be speeded up.

[0043] The ranging frame group storage unit 142 includes an interface circuit that receives the information of the ranging frames output from the ranging frame output unit 137, and a storage unit that stores the information of the ranging frames. The ranging frame group storage unit 142 can output the stored ranging frame information to the distance image calculation unit 143.

[0044] The distance image calculation unit 143 generates a distance image using the information of the ranging frames stored in the ranging frame group storage unit 142. For example, the distance image calculation unit 143 allocates color information to the distance information based on a look-up table, and outputs a distance image frame representing the distance image as a two-dimensional color map. Also, for example, the distance image calculation unit 143 outputs a distance image frame representing the information of the ranging frames as a three-dimensional point cloud map. The format of the distance image frame is not limited to these. Also, the distance image calculation unit 143 outputs the information of the measured distance used for generating the distance image frame to the emission count setting unit 141. In this way, the ranging frame group storage unit 142 and the distance image calculation unit 143 function as calculation units that acquire distance information from the signals output from the light detection device 130.

[0045] The environment monitoring device 150 is a noise information acquisition device that outputs noise information indicating the amount of noise light received by the light detection unit 131 to the emission count setting unit 141 by measuring the noise light from the noise source 192. The environment monitoring device 150 can be, for example, an optical measurement device such as an optical spectrum analyzer or an optical power meter. For example, when the environment monitoring device 150 measures the amount of light around the ranging device, the emission count setting unit 141 calculates the noise from the amount of light and updates the noise information used for acquiring the emission count. Then, the emission count setting unit 141 calculates the emission count for ensuring a predetermined SNR using the updated noise. This calculation may be performed at any time or at a predetermined timing. By arranging the environment monitoring device 150, the emission count setting unit 141 can adjust the emission count according to the noise environment of the ranging device. Therefore, even when the noise environment changes, it is possible to ensure a predetermined SNR, and the ranging accuracy is stabilized.

[0046] Note that it is not essential to arrange the environment monitoring device 150, and the processing may be performed without updating the amount of noise light. In this case, the device configuration can be simplified.

[0047] In FIG. 2, an example is shown in which a distance measuring device is configured by three parts: a light source device 120, a light detection device 130, an arithmetic processing device 140, and an environment monitoring device 150. However, the configuration of the distance measuring device is not limited to this. The combination of the components of the distance measuring device can be changed as appropriate.

[0048] As described above, when two or more photons enter the light detection unit 131 during the period of one time window, a deviation occurs between the number of incident photons and the number of photon detections (number of incident events). Since the square root of the number of photons 2 is approximately 1.4, it is desirable that the SNR of the distance measuring device is 1.4 or less. In general, although the detection accuracy (cumulative probability) can be calculated from the SNR, a detection accuracy of 50% or more is required for photons to be detected with a probability equal to or higher than that of noise. From the viewpoint of obtaining at least this detection accuracy, it is desirable that the SNR of the distance measuring device is 0.7 or more. From the above, it is desirable that the SNR of the distance measuring device is set in the range of 0.7 to 1.4.

[0049] There is a trade-off relationship such that the larger the time constant, the larger the SNR, but the lower the responsiveness. Generally, for transient response, the SNR at which signal quality and responsiveness are somewhat compatible is considered to be a value slightly larger than 1. Therefore, it is more desirable that the SNR of the distance measuring device is set in the range of 1.0 to 1.2.

[0050] FIG. 3 is a diagram schematically showing an outline of the operation of the distance measuring device according to the present embodiment. In FIG. 3, the acquisition periods of a distance image frame, a distance measurement frame, and a light detection frame are schematically shown by arranging blocks horizontally. The horizontal direction in FIG. 3 indicates the passage of time, and one block indicates the acquisition period of one distance image frame, distance measurement frame, and light detection frame. In addition, the timings of the first control pulse and the second control pulse are schematically shown in FIG. 3.

[0051] The distance image frames F1 to Fp in FIG. 3 indicate the generation period of the distance image frames generated by the distance image calculation unit 143. For example, the distance image frame F1 is generated in the period T1, and the distance image frame F2 is generated in the period T2. The length of the period T1 and the length of the period T2 may be the same or different. Note that p is the number of distance image frames.

[0052] The ranging frames SF1 to SFq in FIG. 3 indicate the generation period of the ranging frames generated by the ranging frame output unit 137. For example, the ranging frame SF1 is generated in the period T3, and the ranging frame SFq is generated in the period T4. Note that q is the number of ranging frames. The number of ranging frames is set by the distance image calculation unit 143 and supplied to the light emission count setting unit 141. The ranging frames SF1 to SFq are used for the generation of one distance image frame F1. The ranging frames SF1 to SFq include information indicating the number of photon incident events at different measurement distances.

[0053] The light detection frames MF1 to MF4 in FIG. 3 indicate the generation period of the light detection frames generated by the light detection frame reading unit 135. The light detection frames MF1 to MF4 are used for the generation of one of the ranging frames SF1 to SFq. For example, the light detection frame MF1 used for the generation of the ranging frame SF1 is generated in the period T5. Also, for example, the light detection frame MF1 used for the generation of the ranging frame SFq is generated in the period T6. In the example of FIG. 3, the light detection frame addition unit 136 adds four light detection frames to generate one ranging frame. Since the gradation of each light detection frame is 1 bit, the gradation of the ranging frame is 2 bits.

[0054] The "first control pulse" and "second control pulse" in FIG. 3 indicate the patterns of the control signals output from the gate pulse control unit 132. The first control pulse is a signal for controlling the light emission timing of the pulse light source 121, and the second control pulse is a signal for controlling the timing of the time window for light detection. The gate pulse control unit 132 outputs the first control pulse to the light source control unit 122, and the light source control unit 122 controls the pulse light source 121 based on the first control pulse. The pulse light source 121 repeatedly emits light in the pattern of the first control pulse shown in FIG. 3. The gate pulse control unit 132 outputs the second control pulse to the light detection unit 131, and the light detection unit 131 repeatedly receives light during the periods of the first time window W1 and the second time window W2 of the second control pulse shown in FIG. 3. The time difference between the first control pulse and the second control pulse corresponds to the measurement distance. In the measurement (first measurement) of the light detection frame MF1 (first light detection frame) for generating the ranging frame SF1, the time difference T11 between the first control pulse and the second control pulse corresponds to the measurement distance (first distance) of the ranging frame SF1. In the measurement (second measurement) of the light detection frame MF1 (second light detection frame) for generating the ranging frame SFq, the time difference T12 between the first control pulse and the second control pulse corresponds to the measurement distance (second distance) of the ranging frame SFq.

[0055] FIG. 3 shows the first control pulse and the second control pulse within the period T5 and the first control pulse and the second control pulse within the period T6. The number of pulses of the first control pulse corresponds to the number of light emission times. This number of light emission times is set by the light emission number setting unit 141.

[0056] As shown in FIG. 3, in this embodiment, the first light emission number N1 of the laser pulse light (first pulse light) in the period T5 and the second light emission number N2 of the laser pulse light (second pulse light) in the period T6 are different from each other. In the example of FIG. 3, the second light emission number N2 is larger than the first light emission number N1, and the length of the time interval T7 of the first control pulse in the period T5 is the same as the length of the time interval T8 of the first control pulse in the period T6. In this case, the length of the period T6 is set to be longer than the period T5. Note that the time interval T7 and the time interval T8 may be different.

[0057] The lengths of the periods T5 and T6 of the light detection frame can be appropriately adjusted so that the number of pulses of the first light emission count N1 and the second light emission count N2 are respectively included. For example, the lengths of the periods T5 and T6 of the light detection frame can be the minimum lengths such that the first light emission count N1 and the second light emission count N2 are respectively within the range. In the example of FIG. 3, since the second light emission count N2 is larger than the first light emission count N1, the period T6 is set longer than the period T5. By adjusting the length of the light detection frame period according to the light emission count in this way, the frame rate of the signal output from the distance measuring device can be improved, and the ghost (afterimage) of the subject 191 that may be included in the distance image can be reduced.

[0058] FIG. 4(a) and FIG. 4(b) are graphs for explaining the effect of adjusting the light emission count. FIG. 4(a) is an example of a frequency distribution in the case where the light emission count of the laser pulse light in the light detection frame is adjusted according to the distance as described above. FIG. 4(b) is an example of a frequency distribution in the case where the light emission count of the laser pulse light in the light detection frame is fixed with respect to the distance. The horizontal axes of FIG. 4(a) and FIG. 4(b) indicate the measured distance in arbitrary units, and the vertical axes of FIG. 4(a) and FIG. 4(b) indicate the number of detections of photon incident events. The number of sections on the horizontal axis corresponds to the number of distance measurement frames, and the number of detections on the vertical axis corresponds to the pixel value of the distance measurement frame. The intensity distributions D1 shown in FIG. 4(a) and FIG. 4(b) schematically show the distribution of the intensity of the reflected light from the subject 191. When the measurement is performed ideally, the number of detections approximates the intensity distribution D1.

[0059] As shown in FIG. 4(b), when the number of emissions of the laser pulse light is fixed with respect to the distance, it may be impossible to obtain the number of detections close to the intensity distribution D1. The number of photons incident on the photodetection unit 131 within the period of the time window depends on the distance. As described with reference to FIG. 1(b), the shorter the measurement distance, the larger the number of photons incident on the photodetection unit 131 within the period of the time window. Therefore, the SNR of the distance measurement device changes depending on the measurement distance. The photodetection frame composed of 1-bit information is a signal indicating the presence or absence of a photon incidence event. Therefore, the determination result does not change between the case where one photon is incident on the photodetection unit 131 and the case where a plurality of photons are incident within the period of one time window. That is, when the SNR of the distance measurement device is too high, the signal is in a saturated state, and a deviation occurs between the actually incident number of photons and the detected number of incidence events. Therefore, as shown in FIG. 4(b), a frequency distribution with an unclear peak may be obtained.

[0060] On the other hand, as in the present embodiment, by adjusting the number of emissions, the number of photons incident on the photodetection unit 131 within the period of the time window is appropriately changed according to the measurement distance, so that the deviation between the actually incident number of photons and the detected number of incidence events can be reduced. In this case, the deviation between the number of photons incident on the time window and the number of incidence events is suppressed, and a frequency distribution with a clear peak is obtained as shown in FIG. 4(a). Therefore, the distance measurement can be stabilized.

[0061] The above-described effect becomes more prominent in distance measurement at a relatively short distance (for example, 10 m or less). This is because, as shown in FIG. 1(b), the closer the distance measurement, the greater the dependence of the intensity of light on the distance.

[0062] In addition, the intensity of the reflected pulse light from the subject 191 also depends on the reflectivity of the subject 191. Therefore, in the present embodiment, since the influence of the dependence of the incident number of photons on the measurement distance can be reduced, it is also possible to compare the reflectivities between a plurality of subjects 191 from the detected number of incidence events.

[0063] Next, an example of the distance measurement procedure in the present embodiment will be described with reference to FIG. 5. FIG. 5 is a flowchart showing the operation of the distance measurement device according to the present embodiment. Note that descriptions overlapping with the above description may be omitted or simplified.

[0064] In step S01 after the start of distance measurement, the light emission count setting unit 141 sets the SNR used for calculating the light emission count by reading the preset SNR set value. The subsequent process proceeds to step S03.

[0065] In the generation of the first distance image frame after the start of distance measurement, the SNR generated in step S01 is used, but the SNR setting can be updated in the generation of the second and subsequent distance image frames. In step S02, the environment monitoring device 150 measures the noise light. This noise light can be, for example, sunlight or the like. The environment monitoring device 150 outputs the measurement result of the noise light to the light emission count setting unit 141. The subsequent process proceeds to step S03.

[0066] In step S03, the light emission count setting unit 141 determines whether the measurement conditions have changed based on the measurement result of the noise light. This determination can be based on, for example, the amount of change over time of the light amount of the noise light. If it is determined that the measurement conditions have changed, the process proceeds to step S04 (YES in step S03). If it is determined that the measurement conditions have not changed, the process proceeds to step S06 (NO in step S03). In the case of generating the first distance image frame, the same determination as when the measurement conditions have changed is made. That is, the process proceeds to step S04 (YES in step S03).

[0067] In step S04, the emission count setting unit 141 calculates the number of emissions (the first emission count N1 and the second emission count N2 in FIG. 3) in obtaining one light detection frame for each ranging frame. In generating the distance image frames after the second time, the measurement results of the noise light can be used in this calculation. In the subsequent step S05, the emission count table is updated based on the calculated number of emissions, and the process proceeds to step S06. Note that FIG. 5 shows an operation example when the emission count setting unit 141 refers to the emission count table to set the emission count, but the emission count setting unit 141 may calculate and set the emission count according to a calculation formula. In that case, the process of step S05 can be replaced with the update and rereading of the parameters of the calculation formula.

[0068] Note that the emission count setting unit 141 may hold the initial value of the emission count set in advance. In that case, steps S04 and S05 can be omitted at the time of generating the first distance image frame.

[0069] In step S06, the light detection frame setting unit 134 selects the ranging frame to be measured. The ranging frame selected here is any one of the ranging frames SF1 to SFq in the example of FIG. 3. Then, in step S07, the light detection frame setting unit 134 refers to the emission count table and reads out the number of emissions (the first emission count N1 or the second emission count N2) used for measuring the light detection frame for generating the selected ranging frame. Then, the light detection frame setting unit 134 outputs the information on the number of emissions to the gate pulse control unit 132.

[0070] In step S08, the light detection frame reading unit 135 sequentially reads out the light detection frames MF1 to MF4 for generating the selected ranging frame and outputs them to the light detection frame addition unit 136. The light detection frame addition unit 136 adds the light detection frames MF1 to MF4.

[0071] In step S09, the distance measurement frame output unit 137 outputs the distance measurement frame generated based on the light detection frames MF1 to MF4 to the distance measurement frame group storage unit 142. The distance measurement frame group storage unit 142 stores the acquired distance measurement frames.

[0072] In step S10, the light detection frame setting unit 134 determines whether the acquisition of a predetermined number of distance measurement frames has been completed. In the example of FIG. 3, the light detection frame setting unit 134 determines whether the acquisition of the last distance measurement frame SFq has been completed. If it is determined that the acquisition of the predetermined number of distance measurement frames has not been completed (NO in step S10), the process proceeds to step S11. In step S11, the light detection frame setting unit 134 selects the next distance measurement frame to be measured. The distance measurement frame selected here is the next distance measurement frame after the immediately preceding measured distance measurement frame, and in the example of FIG. 3, it is any one of the distance measurement frames SF2 to SFq. Thereafter, the process proceeds to step S07, and the next distance measurement frame is measured.

[0073] If it is determined in step S10 that the acquisition of the predetermined number of distance measurement frames has been completed (YES in step S10), the process proceeds to step S12. In step S12, the distance image calculation unit 143 generates a distance image frame. Thereafter, the process proceeds to step S02, and the measurement of the noise light and the acquisition of the next distance image frame are performed.

[0074] As described above, according to the present embodiment, the number of light emission times can be adjusted according to the distance to be measured. Therefore, a photoelectric conversion device and a control method for the photoelectric conversion device capable of reducing power consumption are provided.

[0075] Note that when the distance measurement device does not have the environment monitoring device 150, the processes of steps S02 to S05 can be omitted. Thus, some of the processes in the process of FIG. 5 may be omitted, or other processes may be added to the process of FIG. 5.

[0076] Next, a calculation example of the number of light emissions in the first embodiment will be described. In this calculation example, the configuration and measurement conditions of the distance measurement device on which the calculation is based will be described in detail, but the applicable configurations and measurement conditions for the distance measurement device of this embodiment are not limited to this.

[0077] First, the configuration and measurement conditions of the distance measurement device on which the calculation is based will be described. The wavelength of the laser pulse light emitted by the light source device 120 is 940 nm, and the irradiation angle of the laser pulse light is 20 degrees. Also, the time intervals T7 and T8 of the first control pulses in FIG. 3 are both 1000 ns. The time intervals of the first time window W1 and the second time window W2 of the second control pulse are the same as this. The laser pulse light output from the light source device 120 is irradiated onto the subject 191 through a diffuser plate with a diffusion angle of 80 degrees. The average output of the light source device 120 is about 0.18 W. This condition corresponds to Class 1 of the laser safety standard, and the light source device 120 satisfies the eye-safe condition.

[0078] In the light detection unit 131 of the light detection device 130, a 1-million-pixel SPAD is used. The light receiving area of the light detection unit 131 is about 5 mm × 5 mm, and the detection efficiency (Photon Detection Efficiency, PDE) of the light detection unit 131 is 24%. A band-pass filter with a bandwidth of 10 nm and an imaging lens with an angular field of view of 23 degrees are arranged in the optical system of the light detection unit 131.

[0079] The time widths (the length of one period for detecting photons) of the first time window W1 and the second time window W2 of the second control pulse are both 0.2 ns. The distance image frame is composed of 16 distance measurement frames. The measurable range of the distance measurement device is from 0.15 m to 3 m, and this measurable range is divided into 16 measured distances by 16 distance measurement frames. The distance measurement frame is composed of 16 light detection frame numbers. As a result, the gradation of the distance measurement frame is 4 bits.

[0080] The SNR used by the light emission count setting unit 141 for calculating the light emission count is 1.1. The reflectance of the subject 191 is 10%, the illuminance of the noise light is 1000 lux, and it is assumed that the subject 191 is located indoors.

[0081] FIG. 6 is a graph showing an example of calculating the light emission count in the present embodiment. The horizontal axis of FIG. 6 indicates the distance from the distance measuring device to the subject 191, and the vertical axis of FIG. 6 indicates the light emission count used for detecting photons in each time window on a logarithmic scale. Further, the solid line in FIG. 6 is an example of the light emission count calculated so that the SNR is fixed with respect to the distance. The dashed line in FIG. 6 is an example of calculating the light emission count when the light emission count is 1000, that is, when the light emission count is fixed with respect to the distance. The distance measuring device detects the incident events of photons using the light emission count calculated in this way, and outputs a light detection frame corresponding to the number of light emission counts. As shown in FIG. 6, when the SNR is fixed, the number of photons incident during the period of the time window changes in inverse proportion to the square of the distance. Therefore, the closer the distance from the distance measuring device, the fewer the number of light emission counts calculated.

[0082] The total number of light emission counts used for generating the distance image frame matches the integrated value of the light emission count. Therefore, it is understood that the example with the fixed SNR has fewer light emission counts than the example with the fixed light emission count, based on the integrated value of the graph shown in FIG. 6.

[0083] For example, when operating the distance measuring device by applying the above-described conditions, in the example where the light emission count is fixed, the frame rate of the distance image frame is about 4 fps. In contrast, in the example where the SNR is fixed, the frame rate of the distance image frame is about 11 fps. Therefore, by setting the light emission count so as to fix the SNR, the frame rate can be improved.

[0084] In this way, by changing the light emission count according to the measured distance and adjusting the length of the measurement period of the distance measurement frame according to the light emission count, it is possible to achieve both an improvement in the frame rate of the distance image frame and power saving of the distance measuring device.

[0085] In FIG. 6, a mode in which the number of light emissions increases as the distance increases is shown. However, the relationship between the distance and the number of light emissions is not limited to this. For example, the number of light emissions may have a maximum value with respect to the distance. In this case, the number of light emissions decreases at a distance farther than the distance corresponding to the maximum value. By setting the number of light emissions in this way, an operation can be performed to intentionally reduce the detection accuracy of photon incidence events for measurement distances exceeding a desired distance measurement range. As a result, for example, a distance image frame that hides unnecessary distance information in the background can be obtained, and the recognition performance of the subject 191 can be improved. Also, by reducing the number of light emissions at a long distance, the power consumption of the distance measurement device can be reduced. Therefore, power saving of the distance measurement device and recognition performance of the subject 191 can be made compatible.

[0086] [Second Embodiment] In this embodiment, a modified example of the distance measurement operation of the distance measurement device of the first embodiment will be described. In this embodiment, descriptions of elements common to the first embodiment may be omitted or simplified.

[0087] FIG. 7 is a diagram schematically showing an outline of the operation of the distance measurement device according to this embodiment. In FIG. 3 of the first embodiment, an example is shown in which the lengths of the periods T5 and T6 of the light detection frame are appropriately adjusted according to the first number of light emissions N1 and the second number of light emissions N2. That is, as shown in FIG. 3, in the example of the first embodiment, the lengths of the period T5 and the period T6 are different from each other. On the other hand, in this embodiment, as shown in FIG. 7, the lengths of the period T5 and the period T6 are the same regardless of the first number of light emissions N1 and the second number of light emissions N2. As exemplified in the measurement of the light detection frame MF1 of the distance measurement frame SF1 in FIG. 7, by waiting for the light emission operation until the period T5 ends after the light emission of the number of times of the first number of light emissions N1 is completed, the length of the period T5 can be set to a constant length regardless of the number of light emissions.

[0088] According to the configuration of the present embodiment, similarly to the first embodiment, a photoelectric conversion device capable of reducing power consumption and a control method for the photoelectric conversion device are provided. Further, in the configuration of the present embodiment, since a blank period in which pulsed light is not emitted occurs, the average output of the laser pulsed light emitted from the light source device 120 is reduced. Therefore, the light source device 120 is more likely to satisfy the eye-safe conditions of the laser safety standard, and the safety of the distance measuring device can be further improved.

[0089] [Third Embodiment] In this embodiment, a modified example of the method for calculating the number of light emissions of the distance measuring device according to the first embodiment will be described. In this embodiment, the description of the elements common to the first embodiment may be omitted or simplified.

[0090] FIG. 8 is a graph showing an example of the calculation of the number of light emissions in this embodiment. In FIG. 6 of the first embodiment, the calculation of the number of light emissions is performed such that the number of light emissions is continuously set with respect to the distance measurement distance. On the other hand, in this embodiment, the calculation of the number of light emissions is performed by dividing it into a plurality of distance regions. That is, the number of light emissions within the distance region is constant regardless of the distance, and when looking at a plurality of distance regions, the number of light emissions is set to change stepwise with respect to the distance. For example, in the example of FIG. 8, the light emission number setting unit 141 calculates the number of light emissions for three distance regions: a first region less than 1 m, a second region from 1 m to 2 m, and a third region from 2 m to 3 m. And a constant number of light emissions is assigned within each region. Note that the number of divisions of the distance region is not limited to three.

[0091] According to the configuration of the present embodiment, similarly to the first embodiment, a photoelectric conversion device capable of reducing power consumption and a control method for the photoelectric conversion device are provided. Further, in the calculation method of the number of light emissions in the present embodiment, the types of values of the number of light emissions are limited to the number of distance regions. Therefore, since the calculation resources of the light emission number setting unit 141 are reduced compared to the case where the number of light emissions is continuously set with respect to the distance measurement distance, the operation of the distance measuring device can be speeded up.

[0092] [Fourth Embodiment] In this embodiment, a modified example of the device configuration of the distance measuring device according to the first embodiment will be described. In this embodiment, descriptions of elements common to the first embodiment may be omitted or simplified.

[0093] FIG. 9 is a diagram schematically showing an outline of the operation of the distance measuring device according to this embodiment. The distance measuring device according to this embodiment further includes a monitoring device 160 in addition to the configuration of the distance measuring device in FIG. 2 of the first embodiment. The monitoring device 160 is, for example, a radar device or an imaging device. Examples of the imaging device include a visible light camera, an infrared camera, and the like. The monitoring device 160 monitors a predetermined monitoring range and monitors the position, movement, etc. of the subject 191 existing within the monitoring range. The distance measuring device performs control to switch the operating state of the distance measuring device based on the monitoring result.

[0094] A specific example of the control performed based on the monitoring result will be described. For example, the distance image calculation unit 143 may adjust the distance measurement range of the distance image frame so that the detected position is included by detecting the approximate position of the subject 191 based on the monitoring result. Further, the light emission count setting unit 141 may detect the approximate position of the subject 191 based on the monitoring result and perform weighting on the light emission count based on the detected position. In this case, the light emission count for a distance where the possibility of the subject 191 existing is low may be reduced, or the light emission count for a distance where the possibility of the subject 191 existing is high may be increased.

[0095] Further, the distance measuring device may detect the state of an object existing within the distance measurement angular range of the distance measuring device based on the monitoring result, and switch on or off the operating state of the distance measuring device according to the state. When the monitoring device 160 is an imaging device, the monitoring device 160 may detect whether a noise source 192 (for example, a light emitter) exists. When the noise source 192 is detected, the distance measuring device may stop the distance measurement operation targeting the vicinity of the noise source 192. In other words, an operation of specifying the range for performing the distance measurement operation among the distance measurement angular ranges of the distance measuring device based on the monitoring result and selecting the pixels for performing the distance measurement operation among the pixels constituting the light detection unit 131 may be performed.

[0096] According to the configuration of the present embodiment, similarly to the first embodiment, an optoelectronic conversion device capable of reducing power consumption and a control method for the optoelectronic conversion device are provided. Further, in the present embodiment, unnecessary operations can be reduced based on the monitoring results by the monitoring device 160. Therefore, power consumption can be further reduced.

[0097] [Fifth Embodiment] In the present embodiment, a specific configuration example of an optoelectronic conversion device including an avalanche photodiode, which can be applied to the light detection unit 131 of the distance measurement device according to the first to fourth embodiments, will be described. The configuration example of the present embodiment is an example, and the optoelectronic conversion device applicable to the light detection unit 131 is not limited thereto.

[0098] FIG. 10 is a schematic diagram showing the overall configuration of the optoelectronic conversion device 100 according to the present embodiment. The optoelectronic conversion device 100 includes a sensor substrate 11 (first substrate) and a circuit substrate 21 (second substrate) laminated 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 region 12 in which a plurality of pixels 101 arranged in a plurality of rows and a plurality of columns are arranged. The circuit substrate 21 has a first circuit region 22 in which a plurality of pixel signal processing units 103 arranged in a plurality of rows and a plurality of columns are arranged, and a second circuit region 23 arranged on the outer periphery of the first circuit region 22. The second circuit region 23 may include a circuit for controlling a plurality of pixel signal processing units 103. 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 optoelectronic conversion device 100 is a so-called back-illumination type.

[0099] In the present specification, "plan view" refers to viewing from a direction perpendicular to the surface opposite to the light incident surface. Further, the cross section refers to a surface in a direction perpendicular to the surface opposite to the light incident surface of the sensor substrate 11. Note that, although the light incident surface may be a rough surface when viewed microscopically, in that case, the plan view is defined based on the light incident surface when viewed macroscopically.

[0100] Hereinafter, the sensor substrate 11 and the circuit substrate 21 will be described as diced 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. Further, when the sensor substrate 11 and the circuit substrate 21 are diced chips, the photoelectric conversion device 100 may be manufactured by dicing after being stacked in a wafer state, or may be manufactured by stacking after being diced.

[0101] FIG. 11 is a schematic block diagram showing an arrangement example of the sensor substrate 11. In the pixel region 12, a plurality of pixels 101 arranged in a plurality of rows and a plurality of columns are arranged. Each of the plurality of pixels 101 has a photoelectric conversion unit 102 including an avalanche photodiode (hereinafter referred to as APD) as a photoelectric conversion element in the substrate.

[0102] The conductivity type of the charge used as the signal charge among the charge pairs generated in the APD is called the first conductivity type. The first conductivity type refers to a conductivity type in which charges having the same polarity as the signal charge are majority carriers. Also, the conductivity type opposite to the first conductivity type, that is, the conductivity type in which charges having a polarity different from the signal charge are majority carriers is called the second conductivity type. In the APD in the following description, the anode of the APD is set to a fixed potential, and a signal is taken out 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 a configuration in which the cathode of the APD is set to a fixed potential and a signal is taken out from the anode of the APD may also be used. 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. Further, hereinafter, the case where one node of the APD is set to a fixed potential will be described, but a configuration in which the potentials of both nodes fluctuate may also be used.

[0103] FIG. 12 is a schematic block diagram showing a configuration example of the circuit substrate 21. The circuit substrate 21 has a first circuit region 22 in which a plurality of pixel signal processing units 103 arranged in a plurality of rows and a plurality of columns are arranged.

[0104] In addition, on the circuit board 21, a vertical scanning circuit 110, a horizontal scanning circuit 111, a readout circuit 112, pixel output signal lines 113, an output circuit 114, and a control signal generation unit 115 are arranged. The plurality of photoelectric conversion units 102 shown in FIG. 11 and the plurality of pixel signal processing units 103 shown in FIG. 12 are electrically connected via connection wirings provided for each pixel 101, respectively.

[0105] The control signal generation unit 115 is a control circuit that generates control signals for driving the vertical scanning circuit 110, the horizontal scanning circuit 111, and the readout circuit 112, and supplies these control signals to each of these units. Thereby, the control signal generation unit 115 controls the driving timing and the like of each unit.

[0106] Based on the control signal supplied from the control signal generation unit 115, the vertical scanning circuit 110 supplies a control signal to each of the plurality of pixel signal processing units 103. The vertical scanning circuit 110 supplies a control signal for each row to each pixel signal processing unit 103 via drive lines provided for each row in the first circuit region 22. Note that, as will be described later, there may be a plurality of these drive lines for each row. Logic circuits such as a shift register and an address decoder may be used for the vertical scanning circuit 110. Thereby, the vertical scanning circuit 110 selects the row from which the pixel signal processing unit 103 outputs a signal.

[0107] The signal output from the photoelectric conversion unit 102 of the pixel 101 is processed by the pixel signal processing unit 103. The pixel signal processing unit 103 acquires and holds a digital signal by counting the number of pulses output from the APD included in the photoelectric conversion unit 102.

[0108] The pixel signal processing unit 103 does not necessarily have to be provided for each of all the pixels 101 one by one. 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 provides a signal processing function for each pixel 101 by sequentially processing the signals output from each photoelectric conversion unit 102.

[0109] Based on the control signal supplied from the control signal generation unit 115, the horizontal scanning circuit 111 supplies a control signal to the readout circuit 112. The pixel signal processing unit 103 is connected to the readout circuit 112 via the pixel output signal lines 113 provided for each column in the first circuit region 22. The pixel output signal lines 113 of one column are shared by a plurality of pixel signal processing units 103 in the corresponding column. The pixel output signal lines 113 include a plurality of wirings and have at least the function of outputting a digital signal from each pixel signal processing unit 103 to the readout circuit 112 and the function of supplying a control signal for selecting the column for outputting the signal to the pixel signal processing unit 103. Based on the control signal supplied from the control signal generation unit 115, the readout circuit 112 outputs a signal to a storage unit or a signal processing unit outside the photoelectric conversion device 100 via the output circuit 114.

[0110] The arrangement of the photoelectric conversion units 102 in the pixel region 12 may be arranged in a one-dimensional manner. Also, the functions of the pixel signal processing units 103 do not necessarily have to be provided one by one for all the pixels 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 provides a signal processing function for each pixel 101 by sequentially processing the signals output from each photoelectric conversion unit 102.

[0111] As shown in FIGS. 11 and 12, a first circuit region 22 in which a plurality of pixel signal processing units 103 are arranged is arranged in a region overlapping the pixel region 12 in plan view. Then, in plan view, the vertical scanning circuit 110, the horizontal scanning circuit 111, the readout circuit 112, the output circuit 114, and the control signal generation unit 115 are arranged so as to overlap between the end of the sensor substrate 11 and the end of the pixel region 12. In other words, the sensor substrate 11 has a pixel region 12 and a non-pixel region arranged around the pixel region 12. And in the circuit substrate 21, a second circuit region 23 (described above in FIG. 10) in which the vertical scanning circuit 110, the horizontal scanning circuit 111, the readout circuit 112, the output circuit 114, and the control signal generation unit 115 are arranged is arranged in a region overlapping the non-pixel region in plan view.

[0112] Note that the arrangements of the pixel output signal lines 113, the readout circuit 112, and the output circuit 114 are not limited to those shown in FIG. 12. For example, the pixel output signal lines 113 may be arranged to extend in the row direction and shared by a plurality of pixel signal processing units 103 in the corresponding row. And the readout circuit 112 may be arranged such that the pixel output signal lines 113 of each row are connected.

[0113] FIG. 13 is a schematic block diagram showing a configuration example of one pixel of the photoelectric conversion unit 102 and the pixel signal processing unit 103 according to the present embodiment. FIG. 13 schematically shows a more specific configuration example including the connection relationship between the photoelectric conversion unit 102 arranged on the sensor substrate 11 and the pixel signal processing unit 103 arranged on the circuit substrate 21. In FIG. 13, the drive lines between the vertical scanning circuit 110 and the pixel signal processing unit 103 in FIG. 12 are shown as drive lines 213, 214, and 215.

[0114] The photoelectric conversion unit 102 has an APD 201. The pixel signal processing unit 103 has a quench 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 have at least one of the waveform shaping unit 210, the counter circuit 211, the selection circuit 212, and the gating circuit 216.

[0115] The APD 201 generates charges corresponding to incident light by photoelectric conversion. A voltage VL (first voltage) is supplied to the anode of the APD 201. Also, the cathode of the APD 201 is connected to the first terminal of the quench element 202 and the input terminal of the waveform shaping unit 210. A voltage VH (second voltage) higher than the voltage VL supplied to the anode is supplied to the cathode of the APD 201. Thereby, a reverse bias voltage for causing the APD 201 to perform an avalanche multiplication operation is supplied between the anode and the cathode of the APD 201. In the APD 201 to which the reverse bias voltage is supplied, when charges are generated by incident light, these charges cause avalanche multiplication and an avalanche current is generated.

[0116] When a reverse bias voltage is supplied to the APD201, there are two operating modes: the Geiger mode and the linear mode. The Geiger mode is a mode in which the potential difference between the anode and the cathode is operated at a potential difference greater than the breakdown voltage, and the linear mode is a mode in which the potential difference between the anode and the cathode is operated near or below the breakdown voltage.

[0117] An APD operated in the Geiger mode is called a SPAD (Single Photon Avalanche Diode). At this time, for example, the voltage VL (first voltage) is -30V and the voltage VH (second voltage) is 1V. The APD201 may be operated in the linear mode or the Geiger mode. In the case of a SPAD, since the potential difference becomes larger than that of a linear-mode APD and the avalanche multiplication effect becomes remarkable, it is preferably a SPAD.

[0118] The quenching element 202 functions as a load circuit (quenching circuit) when the signal is multiplied by avalanche multiplication. The quenching element 202 suppresses the voltage supplied to the APD201 to suppress avalanche multiplication (quenching operation). Further, the quenching element 202 returns the voltage supplied to the APD201 to the voltage VH by flowing a current corresponding to the voltage drop due to the quenching operation (recharge operation). The quenching element 202 can be, for example, a resistive element.

[0119] The waveform shaping unit 210 shapes the potential change of the cathode of the APD201 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. FIG. 13 shows an example in which one inverter is used as the waveform shaping unit 210, but the waveform shaping unit 210 may use a circuit in which a plurality of inverters are connected in series, or may be other circuits having a waveform shaping effect.

[0120] The gating circuit 216 is a circuit that performs gating to allow the pulse signal output from the waveform shaping unit 210 to pass through for a predetermined period. When the pulse signal can pass through the gating circuit 216, the photons incident on the APD 201 are counted by the subsequent counter circuit 211. Therefore, the gating circuit 216 controls the exposure period during which signal generation based on the incident light is performed in the pixel 101. The period for allowing the pulse signal to pass through is controlled by a control signal supplied from the vertical scanning circuit 110 via the drive line 215. FIG. 13 shows an example in which one AND circuit is used as the gating circuit 216. A pulse signal and a control signal are input to the two input terminals of the AND circuit. The AND circuit outputs the logical product of these to the counter circuit 211. Note that the gating circuit 216 only needs to be able to perform gating, and may have a circuit configuration other than an AND circuit. Also, the waveform shaping unit 210 and the gating circuit 216 may be integrated by using a logic circuit such as a NAND circuit.

[0121] The counter circuit 211 counts the pulse signal output from the waveform shaping unit 210 via the gating circuit 216 and holds a digital signal indicating the count value. Also, when a control signal is supplied from the vertical scanning circuit 110 via the drive line 213, the counter circuit 211 resets the signal it holds.

[0122] A control signal is supplied to the selection circuit 212 from the vertical scanning circuit 110 shown in FIG. 12 via the drive line 214 shown in FIG. 13. In response to this control signal, the selection circuit 212 switches the electrical connection and disconnection between the counter circuit 211 and the pixel output signal line 113. The selection circuit 212 includes, for example, a buffer circuit or the like for outputting a signal corresponding to the value held in the counter circuit 211.

[0123] In the example of FIG. 13, the selection circuit 212 switches the electrical connection and disconnection between the counter circuit 211 and the pixel output signal line 113. However, the method of controlling the signal output to the pixel output signal line 113 is not limited to this. 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, etc., and the signal output to the pixel output signal line 113 may be controlled by switching the electrical connection and disconnection. Further, 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.

[0124] FIGS. 14(a), 14(b), and 14(c) are diagrams for explaining the operation of the APD 201 according to the present embodiment. FIG. 14(a) is a diagram showing the APD 201, the quenching element 202, and the waveform shaping unit 210 extracted from FIG. 13. As shown in FIG. 14(a), the connection node of the input terminals of the APD 201, the quenching element 202, and the waveform shaping unit 210 is defined as node A. Further, as shown in FIG. 14(a), the output side of the waveform shaping unit 210 is defined as node B.

[0125] FIG. 14(b) is a graph showing the time change of the potential of node A in FIG. 14(a). FIG. 14(c) is a graph showing the time change of the potential of node B in FIG. 14(a). In the period from time t0 to time t1, a voltage of VH - VL is applied to the APD 201 in FIG. 14(a). When photons are incident on the APD 201 at time t1, avalanche multiplication occurs in the APD 201. As a result, an avalanche current flows through the quenching element 202, and the potential of node A drops. Thereafter, the amount of potential drop further increases, and the voltage applied to the APD 201 gradually decreases. Then, the avalanche multiplication in the APD 201 stops at time t2. As a result, the voltage level of node A no longer drops below a certain value. Thereafter, in the period from time t2 to time t3, a current that compensates for the voltage drop flows from the node with voltage VH to node A, and at time t3, node A settles to the original potential.

[0126] In the above process, the potential of node B becomes high 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 as a pulse to node B.

[0127] According to the present embodiment, there is provided a photoelectric conversion device using an avalanche photodiode that can be applied to the light detection unit 131 of the distance measurement device according to the first to fourth embodiments.

[0128] [Sixth Embodiment] FIGS. 15(a) and 15(b) are block diagrams of devices related to the in-vehicle distance measurement device in the present embodiment. The device 80 includes a distance measurement unit 803, which is an example of the distance measurement device in the above-described embodiment, and a signal processing device (processing device) that processes signals from the distance measurement unit 803. The device 80 includes a distance measurement unit 803 that measures the distance to an object, and a collision determination unit 804 that determines whether there is a possibility of collision based on the measured distance. Here, the distance measurement unit 803 is an example of distance information acquisition means for acquiring distance information to an object. That is, the distance information is information related to the distance to an object and the like. The collision determination unit 804 may determine the possibility of collision using the distance information.

[0129] Device 80 is connected to a vehicle information acquisition device 810 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. Further, a control ECU 820, which is a control device that outputs a control signal for generating a braking force for the vehicle based on the determination result of the collision determination unit 804, is connected to device 80. Also, device 80 is connected to an alarm device 830 that issues an alarm to the driver based on the determination result of the collision determination unit 804. For example, when the determination result of the collision determination unit 804 indicates a high possibility of collision, the control ECU 820 performs vehicle control such as applying brakes, returning the accelerator, and suppressing engine output to avoid collisions and reduce damage. The alarm device 830 warns the user by sounding an alarm such as a sound, displaying alarm information on the screen of a car navigation system, or applying vibration to the seat belt or steering wheel. These devices of device 80 function as a movement control unit that controls the operation of controlling the vehicle as described above.

[0130] In this embodiment, device 80 measures the distance around the vehicle, for example, in front or behind. Fig. 15(b) shows the device when measuring the distance in front of the vehicle (distance measurement range 850). The vehicle information acquisition device 810 as distance measurement control means sends an instruction to device 80 or the distance measurement unit 803 to perform the distance measurement operation. With such a configuration, the accuracy of distance measurement can be further improved.

[0131] In the above, an example of controlling so as not to collide with other vehicles has been described, but it is also applicable to control for automatically driving following other vehicles, control for automatically driving without deviating from the lane, etc. Further, the device is not limited to vehicles such as automobiles, and can be applied to moving bodies (moving devices) such as ships, airplanes, artificial satellites, industrial robots, and household robots. In addition, it can be applied not only to moving bodies but also to devices that widely utilize object recognition or biometric recognition, such as advanced road traffic systems (ITS) and monitoring systems.

[0132] [Modified Embodiment] The present invention is not limited to the above-described embodiments and can be variously modified. For example, an example in which a part of the configuration of any one of the embodiments is added to another embodiment, or an example in which a part of the configuration of any one of the embodiments is replaced with a part of the configuration of another embodiment is also an embodiment of the present invention.

[0133] The disclosure of this specification includes the complement of the concepts described in this specification. That is, for example, if this specification describes that "A is B" (A = B), even if the description that "A is not B" (A ≠ B) is omitted, this specification is considered to disclose or imply that "A is not B". This is because when the description that "A is B" is made, it is premised that the case where "A is not B" is considered.

[0134] The disclosure of this specification includes the following configurations or methods. (Configuration 1) A light detection unit including a photoelectric conversion element, A control unit that controls the light detection unit and the light source device, A processing unit that processes a signal indicating a detection result of incident light on the light detection unit, having In the first measurement, the control unit controls the light source device so that first pulse light of a first number of light emissions is emitted from the light source device, and controls the light detection unit to detect light incident on the light detection unit in a first time window corresponding to a first distance. In the first measurement, the processing unit outputs a first light detection frame composed of a 1-bit signal by calculating a logical sum with respect to a signal indicating a detection result of a number corresponding to the first number of light emissions output from the light detection unit. In the second measurement, the control unit controls the light source device so that second pulse light of a second number of light emissions different from the first number of light emissions is emitted from the light source device, and controls the light detection unit to detect light incident on the light detection unit in a second time window corresponding to a second distance different from the first distance. In the second measurement, the processing unit outputs a second light detection frame composed of 1-bit signals by calculating a logical sum for a signal indicating the number of detection results corresponding to the number of times of the second light emission output from the light detection unit. A photoelectric conversion device characterized by the above. (Configuration 2) The photoelectric conversion device further includes a light emission number setting unit for setting the first light emission number and the second light emission number, The light emission number setting unit sets the first light emission number based on the first distance and sets the second light emission number based on the second distance. The photoelectric conversion device according to Configuration 1, characterized by the above. (Configuration 3) The light emission number setting unit sets the first light emission number and the second light emission number by referring to a table showing the relationship between the distance and the light emission number. The photoelectric conversion device according to Configuration 2, characterized by the above. (Configuration 4) The table is configured to include a section in which the light emission number is proportional to the square of the distance. The photoelectric conversion device according to Configuration 3, characterized by the above. (Configuration 5) The table is configured to include a section in which the light emission number changes stepwise with respect to the distance. The photoelectric conversion device according to Configuration 3, characterized by the above. (Configuration 6) The light emission number setting unit sets the first light emission number and the second light emission number by using a calculation formula showing the relationship between the distance and the light emission number. The photoelectric conversion device according to Configuration 2, characterized by the above. (Configuration 7) The photoelectric conversion device further includes a noise information acquisition device for acquiring noise information indicating the noise received by the light detection unit, The light emission number setting unit sets the first light emission number and the second light emission number based on the noise information. The photoelectric conversion device according to any one of Configurations 2 to 6, characterized by the above. (Configuration 8) The noise information acquisition device acquires the amount of light around the photoelectric conversion device as the noise information. The photoelectric conversion device according to Configuration 7, characterized in that. (Configuration 9) Further comprising a monitoring device for monitoring a predetermined monitoring range, The first light emission count and the second light emission count are set by the light emission count setting unit based on the monitoring result by the monitoring device. The photoelectric conversion device according to any one of Configurations 2 to 8, characterized in that. (Configuration 10) Further comprising a monitoring device for monitoring a predetermined monitoring range, The control unit switches the operating states of the light detection unit and the light source device based on the monitoring result by the monitoring device. The photoelectric conversion device according to any one of Configurations 2 to 9, characterized in that. (Configuration 11) The first light emission count and the second light emission count are set by the light emission count setting unit so that the signal-to-noise ratio is included in a predetermined range at the first distance and the second distance. The photoelectric conversion device according to any one of Configurations 2 to 10, characterized in that. (Configuration 12) The first light emission count and the second light emission count are set by the light emission count setting unit so that the signal-to-noise ratio is included in the range of 0.7 to 1.4 at the first distance and the second distance. The photoelectric conversion device according to any one of Configurations 2 to 11, characterized in that. (Configuration 13) The first light emission count and the second light emission count are set by the light emission count setting unit so that the signal-to-noise ratio is included in the range of 1.0 to 1.2 at the first distance and the second distance. The photoelectric conversion device according to any one of Configurations 2 to 12, characterized in that. (Configuration 14) The second light emission count is more than the first light emission count, The second distance is larger than the first distance. The photoelectric conversion device according to any one of Configurations 1 to 13, characterized in that... (Configuration 15) The control unit sets the length of the acquisition period of the first light detection frame based on the first light emission count, and sets the length of the acquisition period of the second light detection frame based on the second light emission count. The photoelectric conversion device according to any one of Configurations 1 to 14, characterized in that... (Configuration 16) The second light emission count is greater than the first light emission count. The acquisition period of the second light detection frame is longer than the acquisition period of the first light detection frame. The photoelectric conversion device according to Configuration 15, characterized in that... (Configuration 17) The control unit sets the length of the acquisition period of the first light detection frame to be the same as the length of the acquisition period of the second light detection frame. The photoelectric conversion device according to any one of Configurations 1 to 14, characterized in that... (Configuration 18) The photoelectric conversion device according to any one of Configurations 1 to 17, and An arithmetic unit that acquires distance information from signals based on the first light detection frame and the second light detection frame. A distance measuring device, characterized by comprising... (Configuration 19) A moving body, The distance measuring device according to Configuration 18, and A moving body control unit that controls the moving body based on the distance information. A moving body, characterized by comprising... (Method 20) A control method for a photoelectric conversion device having a light detection unit including a photoelectric conversion element, the method comprising: Controlling the light source device so that first pulsed light of a first light emission count is emitted from the light source device, and detecting light incident on the light detection unit in a first time window corresponding to a first distance. A step of outputting a first optical detection frame composed of 1-bit signals by calculating a logical sum for a signal indicating the number of detection results corresponding to the first number of light emissions output from the optical detection unit; Controlling the light source device so that second pulsed light having a second number of light emissions different from the first number of light emissions is emitted from the light source device, and detecting light incident on the optical detection unit in a second time window corresponding to a second distance different from the first distance; A step of outputting a second optical detection frame composed of 1-bit signals by calculating a logical sum for a signal indicating the number of detection results corresponding to the second number of light emissions output from the optical detection unit; A method for controlling a photoelectric conversion device, characterized by comprising the steps of:

[0135] The present invention can also be realized by supplying a program for realizing one or more functions of the above-described embodiment to a system or device via a network or a storage medium, and causing one or more processors in a computer of the system or device to read and execute the program. Further, it can also be realized by a circuit (for example, ASIC) for realizing one or more functions.

[0136] It should be noted that the above-described embodiments are merely specific examples for implementing the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its technical idea or its main features.

Explanation of Reference Numerals

[0137] 120 Light source device 130 Optical detection device 131 Optical detection unit 132 Gate pulse control unit 133 Light emission control unit 134 Optical detection frame setting unit 135 Optical detection frame reading unit 136 Optical detection frame addition unit 137 Distance measurement frame output unit

Claims

1. A light detection unit including a photoelectric conversion element; A control unit for controlling the light detection unit and the light source device; A processing unit for processing a signal indicating a detection result of incident light to the light detection unit; Characterized by comprising: In the first measurement, the control unit controls the light source device so that first pulse light of a first number of light emissions is emitted from the light source device, and controls the light detection unit to detect light incident on the light detection unit in a first time window corresponding to a first distance. In the first measurement, the processing unit outputs a first light detection frame composed of 1-bit signals by calculating a logical sum for signals indicating detection results of a number corresponding to the first number of light emissions output from the light detection unit. In the second measurement, the control unit controls the light source device so that second pulse light of a second number of light emissions different from the first number of light emissions is emitted from the light source device, and controls the light detection unit to detect light incident on the light detection unit in a second time window corresponding to a second distance different from the first distance. In the second measurement, the processing unit outputs a second light detection frame composed of 1-bit signals by calculating a logical sum for signals indicating detection results of a number corresponding to the second number of light emissions output from the light detection unit. A photoelectric conversion device characterized by the above.

2. Further comprising a light emission number setting unit for setting the first number of light emissions and the second number of light emissions, The light emission number setting unit sets the first number of light emissions based on the first distance and sets the second number of light emissions based on the second distance. The photoelectric conversion device according to claim 1, characterized by the above.

3. The light emission number setting unit sets the first number of light emissions and the second number of light emissions by referring to a table showing the relationship between distance and the number of light emissions. The photoelectric conversion device according to claim 2, characterized by the above.

4. The table is configured to include an interval in which the number of light emissions is proportional to the square of the distance. The photoelectric conversion device according to claim 3, characterized by the above.

5. The table is configured to include an interval in which the number of light emissions changes stepwise with respect to the distance. The photoelectric conversion device according to claim 3, characterized by the above.

6. The light emission number setting unit sets the first number of light emissions and the second number of light emissions using a calculation formula showing the relationship between distance and the number of light emissions. The photoelectric conversion device according to claim 2, characterized by the above.

7. It further has a noise information acquisition device that acquires noise information indicating the noise received by the light detection unit. The number of light emission setting unit sets the first number of light emissions and the second number of light emissions based further on the noise information. The photoelectric conversion device according to claim 2, characterized in that.

8. The noise information acquisition device acquires the amount of light around the photoelectric conversion device as the noise information. The photoelectric conversion device according to claim 7, characterized in that.

9. It further has a monitoring device that monitors within a predetermined monitoring range. The number of light emission setting unit sets the first number of light emissions and the second number of light emissions based further on the monitoring result by the monitoring device. The photoelectric conversion device according to claim 2, characterized in that.

10. It further has a monitoring device that monitors within a predetermined monitoring range. The control unit switches the operating states of the light detection unit and the light source device based on the monitoring result by the monitoring device. The photoelectric conversion device according to claim 2, characterized in that.

11. The number of light emission setting unit sets the first number of light emissions and the second number of light emissions so that the signal-to-noise ratio is included in a predetermined range at the first distance and the second distance. The photoelectric conversion device according to claim 2, characterized in that.

12. The number of light emission setting unit sets the first number of light emissions and the second number of light emissions so that the signal-to-noise ratio is included in the range of 0.7 to 1.4 at the first distance and the second distance. The photoelectric conversion device according to claim 2, characterized in that.

13. The number of light emission setting unit sets the first number of light emissions and the second number of light emissions so that the signal-to-noise ratio is included in the range of 1.0 to 1.2 at the first distance and the second distance. The photoelectric conversion device according to claim 2, characterized in that.

14. The second number of light emissions is more than the first number of light emissions. The second distance is larger than the first distance. The photoelectric conversion device according to claim 1, characterized in that.

15. The control unit sets the length of the acquisition period of the first light detection frame based on the first number of light emissions, and sets the length of the acquisition period of the second light detection frame based on the second number of light emissions. The photoelectric conversion device according to claim 1, characterized in that.

16. The second number of light emissions is more than the first number of light emissions. The acquisition period of the second light detection frame is longer than the acquisition period of the first light detection frame. The photoelectric conversion device according to claim 15, characterized in that.

17. The control unit sets the length of the acquisition period of the first light detection frame and the length of the acquisition period of the second light detection frame to be the same. The photoelectric conversion device according to claim 1, characterized in that.

18. A photoelectric conversion device according to any one of claims 1 to 17, and an arithmetic unit that acquires distance information from signals based on the first light detection frame and the second light detection frame. A distance measuring device, characterized by comprising the same.

19. A moving body, a distance measuring device according to claim 18, and a moving body control unit that controls the moving body based on the distance information. A moving body, characterized by comprising the same.

20. A control method for a photoelectric conversion device having a light detection unit including a photoelectric conversion element, controlling the light source device so that first pulsed light of a first number of light emissions is emitted from the light source device, and detecting light incident on the light detection unit in a first time window corresponding to a first distance; outputting a first light detection frame composed of 1-bit signals by calculating a logical sum for signals indicating detection results of a number corresponding to the first number of light emissions output from the light detection unit; controlling the light source device so that second pulsed light of a second number of light emissions different from the first number of light emissions is emitted from the light source device, and detecting light incident on the light detection unit in a second time window corresponding to a second distance different from the first distance; outputting a second light detection frame composed of 1-bit signals by calculating a logical sum for signals indicating detection results of a number corresponding to the second number of light emissions output from the light detection unit; A control method for a photoelectric conversion device, characterized by comprising the same.

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