Light detection device and ranging device

Abstract

A light detection device according to the present disclosure comprises: a light-receiving unit having a light-receiving surface (pixel array unit 100) in which pixels (10) for generating pixel signals corresponding to irradiated light are arranged in an array of two-dimensional gratings; a control unit (4) for controlling read-out of the pixel signals generated by the light-receiving unit, and light emission of light-emitting points (21) at a light source unit having a light-emitting surface (20) in which the light-emitting points (21) are arranged in an array of two-dimensional gratings; and a generation unit (111) for classifying and integrating the pixel signals read from the light-receiving unit, on the basis of the time from a light-emitting timing at the light source unit to a read-out timing of the pixel signals at the light-receiving unit, and generating a histogram. The control unit (4) causes the light-emitting points (21) included in a light-emitting region (22) obtained by dividing the light-emitting surface (20) to emit light, and reads out the pixel signals from the pixels (10) in a readout region (13) that is included in a light-receiving region (12) corresponding to the light-emitting region (22) on the light-receiving surface (pixel array unit 100) and that is smaller than the light-receiving region (12).

Description

Light detection and ranging devices

[0001] The present disclosure relates to light detection devices and distance measurement devices.

[0002] Toward the realization of fully autonomous driving, the use of LiDAR (Light Detection and Ranging), which can measure the distance between a vehicle and an object with high accuracy, has been proposed. A typical LiDAR system generally uses a direct Time of Flight (ToF) ranging method, which emits a laser beam, detects the reflected light from the target object with a sensor, and calculates the distance to the target object based on the time difference between the emission timing of the laser beam and the detection timing of the sensor.

[0003] JP 2021-92437 A International Publication No. 2021 / 019939

[0004] When installing a LiDAR distance measuring device in a vehicle, a major challenge is reducing power consumption while meeting frame rate and resolution requirements. Long-distance distance measurement, in particular, requires the emission of a large amount of laser light and large-scale parallel processing on the sensor side. Therefore, it is necessary to optimally control both the number of laser light emissions and the number of sensor operations to efficiently perform distance measurement.

[0005] Therefore, an object of the present disclosure is to provide a light detection device and a distance measuring device that can efficiently perform distance measurement operations.

[0006] The photodetection device according to the present disclosure includes a light receiving unit having a light receiving surface on which pixels that generate pixel signals in response to irradiated light are arranged in a two-dimensional grid array, a control unit that controls reading out of the pixel signals generated in the light receiving unit and light emission of light emitting points in a light source unit having a light emitting surface on which the light emitting points are arranged in a two-dimensional grid array, and a generation unit that classifies and accumulates the pixel signals read out from the light receiving unit based on the time from the light emission timing in the light source unit to the readout timing of the pixel signals in the light receiving unit, and generates a histogram, in which the control unit causes the light emitting points included in light emitting regions obtained by dividing the light emitting surface to emit light, and reads out the pixel signals from the pixels in a readout region that is smaller than the light receiving region and that is included in a light receiving region on the light receiving surface that corresponds to the light emitting region.

[0007] 1 is a diagram schematically illustrating distance measurement using a direct ToF method applicable to each embodiment. FIG. 2 is a diagram illustrating an example histogram based on the time at which a light receiving unit receives light, applicable to each embodiment. FIG. 3 is a block diagram illustrating the configuration of an example of an electronic device using a distance measuring device according to each embodiment. FIG. 4 is a block diagram illustrating the configuration of an example of a distance measuring device applicable to each embodiment in more detail. FIG. 5 is a diagram illustrating an example of the basic configuration of a pixel circuit applicable to each embodiment. FIG. 6 is a schematic diagram illustrating an example of the configuration of a device applicable to a distance measuring device according to each embodiment. FIG. 7 is a schematic diagram illustrating the configuration of an example of a light source unit applicable to the embodiments. FIG. 8 is a schematic diagram illustrating an example of a pixel configuration applicable to the embodiments. FIG. 9 is a schematic diagram illustrating a method of generating a histogram applicable to the embodiments. FIG. 10 is a schematic diagram illustrating distance measurement operation according to existing technology. FIG. 11 is a schematic diagram illustrating distance measurement operation according to the embodiment. FIG. 12 is a schematic diagram illustrating an example of division of a light receiving region according to the embodiment. FIG. 13 is a schematic diagram illustrating an example where a plurality of light emitting regions that emit light simultaneously are set on a light emitting surface, according to the embodiment. FIG. 14 is a schematic diagram illustrating an example where one light emitting region is set on a light emitting surface, according to the embodiment. FIG. 15 is a schematic diagram illustrating an example where a readout region in a light receiving region is changed for each light emission of a light emitting region, according to the embodiment. 1 is a schematic diagram showing an example of a case where a readout area in a light-receiving area is changed for each multiple light emissions of a light-emitting area according to an embodiment. FIG. 2 is a schematic diagram for explaining another example of a case where a readout area in a light-receiving area is changed for each multiple light emissions of a light-emitting area according to an embodiment. FIG. 3 is a schematic diagram showing an example of a method of dividing a light-receiving area applicable to an embodiment. FIG. 4 is a schematic diagram for explaining a first setting method of a readout area when a light-emitting area is swept within a light-emitting surface according to an embodiment. FIG. 5 is a schematic diagram for explaining more specifically the first setting method of a readout area when a light-emitting area is swept within a light-emitting surface according to an embodiment. FIG. 6 is a schematic diagram for explaining a second setting method of a readout area when a light-emitting area is swept within a light-emitting surface according to an embodiment. FIG. 7 is a schematic diagram for explaining more specifically the second setting method of a readout area when a light-emitting area is swept within a light-emitting surface according to an embodiment. FIG. 8 is a block diagram showing an example of a general configuration of a vehicle control system. FIG. 9 is an explanatory diagram showing an example of installation positions of an outside vehicle information detection unit and an imaging unit.

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, the same components are denoted by the same reference numerals, and redundant description will be omitted.

[0009] Hereinafter, embodiments of the present disclosure will be described in the following order: 1. Technology applicable to the embodiments 1-1. Overview of distance measurement using the direct ToF method 1-2. Configuration applicable to the embodiments 1-3. Histogram generation method applicable to the embodiments 2. Embodiments of the present disclosure 2-1. Overview of the embodiments 2-2. Specific examples of the embodiments 2-3. Example of sweeping the light-emitting region 3. Application examples of the embodiments of the present disclosure

[0010] (1. Technology Applicable to Embodiments) The present disclosure relates to technology for measuring distance using light. Prior to describing each embodiment of the present disclosure, technology applicable to each embodiment will be described to facilitate understanding. In each embodiment, a direct ToF (Time Of Flight) method is applied as a distance measurement method. The direct ToF method is a method in which light emitted from a light source is reflected by an object to be measured and received by a light receiving element, and distance measurement is performed based on the time difference between the light emission timing and the light reception timing.

[0011] (1-1. Overview of distance measurement using direct ToF method) Distance measurement using the direct ToF method will be briefly described using Figures 1 and 2. Figure 1 is a diagram schematically showing distance measurement using the direct ToF method that can be applied to each embodiment. Distance measuring device 300 includes a light source unit 301 and a light receiving unit 302. Light source unit 301 is, for example, a laser diode, and is driven to emit laser light in pulses. Light emitted from light source unit 301 is reflected by object to be measured 303 and received by light receiving unit 302 as reflected light. Light receiving unit 302 includes a light receiving element that converts light into an electrical signal by photoelectric conversion, and outputs a signal corresponding to the received light.

[0012] Here, the time when the light source unit 301 emits light (light emission timing) is defined as time t0, and the time when the light emitted from the light source unit 301 is reflected by the object under test 303 and received by the light receiving unit 302 (light reception timing) is defined as time t1. The constant c is the speed of light (2.9979×108 [m / sec], the distance D between the distance measuring device 300 and the object to be measured 303 is calculated by the following equation (1): D=(c / 2)×(t1−t0) (1)

[0013] The distance measuring device 300 repeats the above process multiple times. The light receiving unit 302 may include multiple light receiving elements, and the distance D may be calculated based on the light receiving timing at which the reflected light is received by each light receiving element. The distance measuring device 300 calculates the distance D based on the time t0 from the light emission timing to the light receiving timing at which the light is received by the light receiving unit 302. m (light receiving time t m The data (called "data") is classified into classes (bins) to generate a histogram.

[0014] The light receiving unit 302 receives light for a time t m The light received by the light receiving unit 302 is not limited to light emitted by the light source unit 301 and reflected by the object to be measured. For example, ambient light around the distance measuring device 300 (light receiving unit 302) is also received by the light receiving unit 302.

[0015] 2 is a diagram showing an example of a histogram based on the time at which the light receiving unit 302 receives light, which can be applied to each embodiment. In FIG. 2, the horizontal axis indicates bins, and the vertical axis indicates the frequency of each bin. A bin is a time period for receiving light t m are classified for each predetermined unit time d. Specifically, bin #0 is m < d, bin #1 is d≦t m < 2 × d, bin #2 is 2 × d ≦ t m <3×d, ..., bin #(N-2) is (N-2)×d≦t m <(N-1)×d. The exposure time of the light receiving unit 302 is set to time t ep In this case, t ep = N × d.

[0016] The distance measuring device 300 receives light at a time t mThe number of times the frequency of acquisition is counted based on the bin to determine the frequency 310 for each bin, and a histogram is generated. Here, the light receiving unit 302 receives light other than the reflected light that is the light emitted from the light source unit 301. An example of such light other than the target reflected light is the above-mentioned ambient light. The portion indicated by range 311 in the histogram includes the ambient light component due to the ambient light. The ambient light is light that is randomly incident on the light receiving unit 302, and acts as noise in the target reflected light.

[0017] On the other hand, the reflected light of interest is light received according to a specific distance, and appears in the histogram as an active light component 312. The bin corresponding to the frequency of the peak in this active light component 312 is the bin corresponding to the distance D to the object under measurement 303. By acquiring the representative time of that bin (for example, the time at the center of the bin) as the above-mentioned time t1, the distance measuring device 300 can calculate the distance D to the object under measurement 303 according to the above-mentioned formula (1). In this way, by using multiple light reception results, it is possible to perform appropriate distance measurement despite random noise.

[0018] (1-2. Configuration applicable to the embodiments) Fig. 3 is a block diagram showing the configuration of an example of an electronic device using a distance measuring device according to each embodiment. In Fig. 3, an electronic device 6 includes a distance measuring device 1, a light source unit 2, a memory unit 3, a control unit 4, and an optical system 5.

[0019] The light source unit 2 corresponds to the above-described light source unit 301 and is a laser diode, which is driven to emit, for example, pulsed laser light. A VCSEL (Vertical Cavity Surface Emitting Laser) that emits laser light as a surface light source can be used as the light source unit 2. Alternatively, the light source unit 2 may be an array in which laser diodes are arranged in a line, and the laser light emitted from the laser diode array may be scanned in a direction perpendicular to the line. Furthermore, a laser diode may be used as a single light source, and the laser light emitted from the laser diode may be scanned in both horizontal and vertical directions.

[0020] The distance measuring device 1 includes a plurality of light receiving elements corresponding to the light receiving unit 302. The plurality of light receiving elements are arranged, for example, in a two-dimensional lattice pattern (matrix pattern) to form a light receiving surface. The optical system 5 guides light incident from the outside to the light receiving surface included in the distance measuring device 1.

[0021] The control unit 4 controls the overall operation of the electronic device 6. For example, the control unit 4 supplies a light emission trigger to the distance measuring device 1, which is a trigger for causing the light source unit 2 to emit light. The distance measuring device 1 causes the light source unit 2 to emit light at a timing based on this light emission trigger, and stores the time t0 indicating the light emission timing. Furthermore, the control unit 4 sets a pattern for distance measurement in the distance measuring device 1 in response to, for example, an external instruction.

[0022] The distance measuring device 1 receives time information (light receiving time t m ) is acquired within a predetermined time range, and the frequency of each bin is calculated to generate the above-mentioned histogram. The distance measuring device 1 further calculates the distance D to the object based on the generated histogram. Information indicating the calculated distance D is stored in the storage unit 3.

[0023] Fig. 4 is a block diagram showing in more detail the configuration of an example of a distance measuring device 1 applicable to each embodiment. In Fig. 4, the distance measuring device 1 includes a pixel array unit 100, a distance measurement processing unit 101, a pixel control unit 102, an overall control unit 103, a clock generation unit 104, an emission timing control unit 105, and an interface (I / F) 106. The pixel array unit 100, distance measurement processing unit 101, pixel control unit 102, overall control unit 103, clock generation unit 104, emission timing control unit 105, and interface (I / F) 106 are arranged on, for example, a single semiconductor chip.

[0024] 4, an overall control unit 103 controls the overall operation of the distance measuring device 1 in accordance with, for example, a pre-installed program. The overall control unit 103 can also execute control in accordance with an external control signal supplied from the outside. A clock generation unit 104 generates one or more clock signals used in the distance measuring device 1 based on a reference clock signal supplied from the outside. A light emission timing control unit 105 generates a light emission control signal indicating the light emission timing in accordance with a light emission trigger signal supplied from the outside. The light emission control signal is supplied to the light source unit 2 and also to the distance measurement processing unit 101.

[0025] Furthermore, if the light source unit 2 is a VCSEL or a laser diode array, the light emission timing control unit 105 may, under the control of the overall control unit 103, include instructions for setting the light emitting point or light emitting area to be emitted in the light emission control signal.

[0026] The pixel array unit 100 is a sensor for detecting light, and includes a plurality of pixels 10 arranged in a two-dimensional lattice, each including a light-receiving element and a drive circuit for driving the light-receiving element. A pixel region (referred to as an effective region) including effective pixels 10 in the pixel array unit 100 is the FoV (Field of View) of the sensor. Note that effective pixels 10 refer to pixels 10 included in the pixel array unit 100 that contribute to reading pixel signals in response to received light. The effective pixels 10 may be, for example, pixels 10 included in the pixel array unit 100, excluding pixels 10 arranged on the periphery of the pixel array unit 100 that are used for characteristic measurements (measurement of dark current), etc.

[0027] Hereinafter, unless there is a need to particularly distinguish, the pixel array section 100 refers to the effective area of ​​the pixel array section 100. Furthermore, the effective area constitutes a light receiving section that receives light irradiated in the pixel array section 100.

[0028] The operation of each pixel 10 is controlled by the pixel control unit 102 in accordance with instructions from the overall control unit 103. For example, the pixel control unit 102 can control the readout of pixel signals from each pixel 10 for each block including (p × q) pixels 10, with p pixels in the row direction and q pixels in the column direction. Furthermore, the pixel control unit 102 can read pixel signals from each pixel 10 by scanning each pixel 10 in the row direction and then in the column direction, using the block as a unit. This is not a limitation, and the pixel control unit 102 can also control each pixel 10 individually. Furthermore, the pixel control unit 102 can set a predetermined region of the pixel array unit 100 as a target region and set pixels 10 included in the target region as target pixels 10 from which pixel signals are to be read out. Furthermore, the pixel control unit 102 can scan multiple rows (multiple lines) together and then further scan the target region in the column direction to read pixel signals from each pixel 10.

[0029] The pixel signals read out from each pixel 10 are supplied to a ranging processing unit 101. The ranging processing unit 101 includes a conversion unit 110, a generation unit 111, and a signal processing unit 112.

[0030] The pixel signals read out from each pixel 10 and output from the pixel array unit 100 are supplied to the conversion unit 110. Here, the pixel signals are read out asynchronously from each pixel 10 and supplied to the conversion unit 110. That is, the pixel signals are read out from the light receiving elements in accordance with the timing at which light is received in each pixel 10 and output.

[0031] The conversion unit 110 converts the pixel signals supplied from the pixel array unit 100 into digital information. That is, the pixel signals supplied from the pixel array unit 100 are output in accordance with the timing at which light is received by the light receiving element included in the pixel 10 to which the pixel signal corresponds. The conversion unit 110 converts the supplied pixel signals into time information indicating the timing.

[0032] The generation unit 111 generates a histogram based on the time information into which the pixel signals are converted by the conversion unit 110. Here, the generation unit 111 counts the time information based on the unit time d set by the setting unit 113 to generate a histogram. The histogram generation process by the generation unit 111 will be described in detail later.

[0033] The signal processing unit 112 performs predetermined arithmetic processing based on the histogram data generated by the generation unit 111, and calculates, for example, distance information. For example, the signal processing unit 112 creates a curve approximation of the histogram based on the histogram data generated by the generation unit 111. The signal processing unit 112 detects peaks in the curve obtained by approximating the histogram, and can calculate the distance D based on the detected peaks.

[0034] When performing curve approximation of a histogram, the signal processing unit 112 can perform filtering on the curve obtained by approximating the histogram. For example, the signal processing unit 112 can suppress noise components by performing low-pass filtering on the curve obtained by approximating the histogram.

[0035] The distance information obtained by the signal processing unit 112 is supplied to the interface 106. The interface 106 outputs the distance information supplied from the signal processing unit 112 to the outside as output data. As the interface 106, for example, a Mobile Industry Processor Interface (MIPI) can be applied.

[0036] In the above description, the distance information calculated by the signal processing unit 112 is output to the outside via the interface 106, but this is not limited to this example. That is, the histogram data, which is the histogram data generated by the generation unit 111, may be output to the outside from the interface 106. In this case, the distance measurement condition information set by the setting unit 113 can omit information indicating the filter coefficients. The histogram data output from the interface 106 is supplied to, for example, an external information processing device and processed as appropriate.

[0037] The information that the ranging processing unit 101 acquires based on the pixel signals read out from the pixel array unit 100 is not limited to distance information. The ranging processing unit 101 may also acquire ambient light information based on the pixel signals (see FIG. 2). The ranging processing unit 101 can also acquire the light emission intensity of the light source unit 2, and can also acquire the reflectance of an object based on the acquired light emission intensity, the intensity of light reflected from the object, and distance information indicating the distance to the object.

[0038] 5 is a diagram showing an example of the basic configuration of a pixel 10 applicable to each embodiment. In FIG. 5, the pixel 10 includes a light receiving element 1000, transistors 1100, 1102, and 1103, an inverter 1104, a switch unit 1101, and an AND circuit 1110.

[0039] The light receiving element 1000 converts incident light into an electrical signal by photoelectric conversion and outputs the signal. In each embodiment, the light receiving element 1000 converts incident photons into an electrical signal by photoelectric conversion and outputs a pulse corresponding to the incident photons. In each embodiment, an avalanche photodiode operated in Geiger mode is used as the light receiving element 1000. This avalanche photodiode operated in Geiger mode is called a single photon avalanche diode (SPAD). A SPAD has the property that, when a large negative voltage that generates avalanche multiplication is applied to the cathode, electrons generated in response to the incidence of one photon undergo avalanche multiplication, resulting in a large current flow. Utilizing this property of the SPAD, the incidence of one photon can be detected with high sensitivity.

[0040] Hereinafter, the description will be given assuming that the light receiving element 1000 is a SPAD.

[0041] In FIG. 5 , the cathode of the photodetector 1000, which is a SPAD, is connected to a coupling element 1120, and the anode is connected to a voltage source of voltage (−Vbd). The voltage (−Vbd) is a large negative voltage for generating avalanche multiplication in the SPAD. The coupling element 1120 is connected to one end of a switch element 1101, which is controlled to be on (closed) or off (open) in response to a signal EN_PR. The other end of the switch element 1101 is connected to the drain of a transistor 1100, which is a P-channel metal oxide semiconductor field effect transistor (MOSFET). The source of the transistor 1100 is connected to a power supply voltage Vdd. The gate of the transistor 1100 is connected to a coupling element 1121, to which a reference voltage Vref is supplied.

[0042] The transistor 1100 is a current source that outputs a current from its drain that corresponds to the power supply voltage Vdd and the reference voltage Vref. With this configuration, a reverse bias is applied to the light receiving element 1000. When a photon is incident on the light receiving element 1000 while the switch unit 1101 is on, avalanche multiplication begins, and a current flows from the cathode to the anode of the light receiving element 1000.

[0043] A signal extracted from the connection point between the drain of the transistor 1100 (one end of the switch unit 1101) and the cathode of the light receiving element 1000 is input to the inverter 1104. The inverter 1104 performs, for example, threshold determination on the input signal, and inverts the signal each time the signal exceeds the threshold in the positive or negative direction, and outputs the signal as a pulsed signal Vpls. In other words, the inverter 1104 can be said to be a conversion circuit that converts the output of the light receiving element 1000 into a pulse signal.

[0044] The signal Vpls output from the inverter 1104 is input to a first input terminal of the AND circuit 1110. The signal EN_F is input to a second input terminal of the AND circuit 1110. When the signals Vpls and EN_F are both in a high state, the AND circuit 1110 outputs the signal Vpls from the pixel 10 via a terminal 1122.

[0045] 5 , the coupling portion 1120 is further connected to the drains of transistors 1102 and 1103, which are N-channel MOSFETs. The sources of transistors 1102 and 1103 are connected to, for example, ground potential. The gate of transistor 1102 receives signal XEN_SPAD_V. The gate of transistor 1103 receives signal XEN_SPAD_H. When at least one of transistors 1102 and 1103 is in the off state, the cathode of the light receiving element 1000 is forced to ground potential, and the signal Vpls is fixed to a low state.

[0046] The signals XEN_SPAD_V and XEN_SPAD_H are used as vertical and horizontal control signals, respectively, for the two-dimensional lattice in which the pixels 10 are arranged in the pixel array unit 100. This makes it possible to control the on / off state of each pixel 10 included in the pixel array unit 100 for each pixel 10. The on state of the pixel 10 is a state in which the signal Vpls can be output, and the off state of the pixel 10 is a state in which the signal Vpls cannot be output.

[0047] For example, in the pixel array unit 100, the signal XEN_SPAD_H turns on the transistor 1103 for q consecutive columns of a two-dimensional lattice, and the signal XEN_SPAD_V turns on the transistor 1102 for p consecutive rows. This enables the output of each light receiving element 1000 in a block of p rows by q columns. Furthermore, the signal Vpls is output from the pixel 10 by the AND circuit 1110 through a logical AND with the signal EN_F, so that it is possible to more precisely control whether the output of each light receiving element 1000 enabled by the signals XEN_SPAD_V and XEN_SPAD_H is enabled or disabled.

[0048] Furthermore, for example, by supplying a signal EN_PR that turns off the switch unit 1101 to a pixel 10 including a light receiving element 1000 whose output is to be disabled, the supply of the power supply voltage Vdd to the light receiving element 1000 can be stopped, and the pixel 10 can be turned off. This makes it possible to reduce power consumption in the pixel array unit 100.

[0049] These signals XEN_SPAD_V, XEN_SPAD_H, EN_PR, and EN_F are generated by the overall control unit 103 based on parameters stored in a register or the like of the overall control unit 103. The parameters may be stored in the register in advance, or may be stored in the register in accordance with an external input. The signals XEN_SPAD_V, XEN_SPAD_H, EN_PR, and EN_F generated by the overall control unit 103 are supplied to the pixel array unit 100 by the pixel control unit 102.

[0050] Note that the above-described control by the signals EN_PR, XEN_SPAD_V, and XEN_SPAD_H using the switch unit 1101 and transistors 1102 and 1103 is control by analog voltage. On the other hand, control by the signal EN_F using the AND circuit 1110 is control by logic voltage. Therefore, control by the signal EN_F can be performed at a lower voltage than control by the signals EN_PR, XEN_SPAD_V, and XEN_SPAD_H, and is easier to handle.

[0051] Fig. 6 is a schematic diagram showing an example of the configuration of a device applicable to the distance measuring device 1 according to each embodiment. In Fig. 6, the distance measuring device 1 is configured by stacking a light receiving chip 1200 and a logic chip 1201, each of which is made up of a semiconductor chip. For the sake of explanation, Fig. 5 shows the light receiving chip 1200 and the logic chip 1201 in a separated state.

[0052] In the light receiving chip 1200, the light receiving elements 1000 included in each of the plurality of pixels 10 are arranged in a two-dimensional lattice pattern in the region of the pixel array section 100. The surface on which these light receiving elements 1000 are arranged forms a light receiving surface that receives light irradiated onto the pixel array section 100. Note that, hereinafter, the light receiving elements 1000 may be described as pixels 10.

[0053] In the pixel 10, the transistors 1100, 1102, and 1103, the switch unit 1101, the inverter 1104, and the AND circuit 1110 are formed on a logic chip 1201. The cathode of the light receiving element 1000 is connected between the light receiving chip 1200 and the logic chip 1201 via a coupling unit 1120 such as a CCC (Copper-Copper Connection).

[0054] The logic chip 1201 is provided with a logic array section 1210 including a signal processing section that processes signals acquired by the light receiving element 1000. The logic chip 1201 may further be provided, in proximity to the logic array section 1210, with a signal processing circuit section 1211 that processes signals acquired by the light receiving element 1000, and an element control section 1212 that controls the operation of the distance measuring device 1.

[0055] For example, the signal processing circuit unit 1211 may include the above-described distance measurement processing unit 101. The element control unit 1212 may include the above-described pixel control unit 102, overall control unit 103, clock generation unit 104, light emission timing control unit 105, and interface 106.

[0056] Note that the configurations on the photosensor chip 1200 and the logic chip 1201 are not limited to this example. Furthermore, the element control unit 1212 can be arranged, for example, near the photosensor 1000 for other driving or control purposes in addition to controlling the logic array unit 1210. In addition to the arrangement shown in FIG. 6 , the element control unit 1212 can be provided in any region of the photosensor chip 1200 and the logic chip 1201 so as to have any function.

[0057] 7 is a schematic diagram showing an example of the configuration of a light source unit 2 applicable to the embodiment. In FIG. 7, the light source unit 2 is configured such that light-emitting points 21 are arranged in a two-dimensional lattice pattern on a light-emitting surface 20. For each light-emitting point 21, control lines may be provided in the row and column directions of the two-dimensional lattice, and the light emission of each light-emitting point 21 may be controlled by these control lines. By such control, the light emission of each light-emitting point 21 can be controlled, for example, in units of blocks each including a plurality of light-emitting points 21.

[0058] (1-3. Histogram Generation Method Applicable to the Embodiment) Next, a histogram generation method applicable to the embodiment will be described.

[0059] 8 is a schematic diagram showing an example of a pixel configuration applicable to the embodiment. In the embodiment, each pixel 10 included in the pixel array unit 100 is controlled in units of a block including a plurality of pixels 10. In the example of FIG. 8, each pixel 10 is controlled in units of a block 11 including 16 pixels, 4 pixels horizontally by 4 pixels vertically. This block 11 is treated as a single pixel and is called a macropixel. In the following description, the block 11 will be referred to as a macropixel 11.

[0060] FIG. 9 is a schematic diagram for explaining a method for generating a histogram applicable to the embodiment.

[0061] For the sake of explanation, it is assumed here that one macropixel 11 includes four pixels 101, 102, 103 and 104, as shown in section (a) of FIG.

[0062] As shown in section (b) of Figure 9, when light is irradiated onto each of the pixels 101 to 104 on the light receiving surface, the signal output from the light receiving element 1000 is converted into a pulse. The light receiving element 1000 continues to react to the reception of one photon for a predetermined time (e.g., 5 ns), during which the output of the pixel 10 is set to a high state. If the light receiving element 1000 receives another photon during this predetermined time, it continues to react in response to the received light.

[0063] In the example of section (b) of Figure 9, pixel 101 has its output set to a high state from between times t1 and t2 to between times t5 and t6 in response to light reception. Pixel 102 has its output set to a high state from just before time t1 to between times t4 and t5. Pixel 103 has its output set to a high state from between times t2 and t3 to between times t6 and t7 in response to light reception. Similarly, pixel 104 has its output set to a high state from just before time t1 to between times t4 and t ５ The output is kept high during this time.

[0064] The ranging processing unit 101 performs sampling on the outputs of the pixels 101 to 104 at times t1 to t7 using the conversion unit 110, and generates a histogram 330 using the generation unit 111. The ranging processing unit 101 processes the pixels 101 to 104 included in the macro pixel 11 collectively.

[0065] Specifically, in this example, at time t1, the outputs of pixels 102 and 104 are integrated to a count value of "2," and at time t2, the outputs of pixels 101, 102, and 104 are integrated to a count value of "3." Similarly, from time t3 onwards, the outputs of pixels 101 to 104 are integrated at each of times t3 to t7. The generation unit 111 generates a histogram 330 based on the integrated values ​​of the outputs of pixels 101 to 104 at each of times t1 to t7.

[0066] (2. Embodiments of the Present Disclosure) (2-1. Overview of the Embodiments) First, an outline of an embodiment of the present disclosure will be described. Fig. 10 is a schematic diagram for explaining a distance measurement operation using existing technology. As shown in section (a) of Fig. 10, a plurality of light-emitting areas 221 to 224, each including a plurality of light-emitting points 21, are set on a light-emitting surface 20, and the light-emitting points 21 included in each of the light-emitting areas 221 to 224 are caused to emit light.

[0067] In the existing technology, as shown in section (b) of Figure 10, for a pixel array unit 100 which is a light-receiving surface, pixel signals from pixels 10 are read out in light-receiving regions 12 to 12 which respectively correspond to a plurality of light-emitting regions 22 to 22 in a light-emitting surface 20. In other words, each of the light-receiving regions 12 to 12 is used in its entirety as a readout region for reading out pixel signals from pixels 10.

[0068] In this case, the number of pixels 10 that the pixel array unit 100 can simultaneously read out is limited to a certain extent due to factors such as the load imposed by parallel calculation processing for histogram generation and power consumption in the pixel array unit 100. Generally, the number of pixels 10 that can be simultaneously read out is small compared to the number of pixels 10 included in the light receiving regions 12 to 12. Therefore, existing technologies result in unnecessary laser emission or unnecessary pixel reading.

[0069] Patent Documents 1 and 2 disclose a method for limiting the readout area on the sensor, but do not consider the above-mentioned unnecessary laser emission or unnecessary pixel readout.

[0070] Fig. 11 is a schematic diagram for explaining the distance measurement operation according to the embodiment. In Fig. 11, section (a), similar to section (a) of Fig. 10 described above, shows how a plurality of light-emitting areas 22 to 22, each including a plurality of light-emitting points 21, are set on light-emitting surface 20, and the light-emitting points 21 included in each of light-emitting areas 22 to 22 are caused to emit light. Note that hereinafter, "causing the light-emitting points 21 included in light-emitting area 22 to emit light" will be appropriately described as "causing light-emitting area 22 to emit light," etc.

[0071] 11, for each of the light-receiving regions 12 to 12 corresponding to each of the light-emitting regions 22 to 22, a readout region 13 is set that is smaller than the light-receiving region 12 to 12, i.e., that includes fewer pixels 10. Reading of the pixels 10 in each of the light-receiving regions 12 to 12 is performed for the pixels 10 included in the readout region 13 of each of the light-receiving regions 12 to 12. The size of the readout region 13, i.e., the number of pixels 10 included, is set appropriately based on the load due to parallel calculation processing related to histogram generation and the power consumption of the pixel array unit 100, etc.

[0072] As shown in section (c) of Fig. 11 , the light-receiving region 12 has a field angle corresponding to each laser light emitted from each light-emitting point 21 in the light-emitting region 22. In the example of section (c), the light-receiving region 12 is divided into three regions (1) to (3), and each of these regions (1) to (3) is set as a readout region 13. For example, region (1) is set as the readout region 13 for the first light emission of the light-emitting region 22, and region (2) is set as the readout region 13 for the second light emission. Furthermore, region (3) is set as the readout region 13 for the third light emission of the light-emitting region 22. In this manner, in the embodiment, the readout region 13 in the light-receiving region 12 is changed for each of one to multiple light emissions in the light-emitting region 22, and ultimately, readout is performed from all of the pixels 10 included in the light-receiving region 12.

[0073] The setting of the light-emitting region 22 on the light-emitting surface 20 and the setting of the readout region 13 in the pixel array unit 100 may be controlled by the overall control unit 103 shown in Fig. 4. The overall control unit 103 may control these settings in response to, for example, an external control signal. Alternatively, the overall control unit 103 may control these settings in accordance with information stored in a storage area such as a register of the overall control unit 103.

[0074] In this embodiment, when multiple readout operations are performed in each light receiving region 12 on the sensor, the readout region 13 that performs readout within the light receiving region 12 is switched between the divided regions of the light receiving region 12. This makes it possible to efficiently perform readout in the light receiving region 12. This makes it possible to complete readout operations for the entire effective region of the pixel array unit 100, i.e., the entire Field of View (FoV), while suppressing unnecessary readout operations and light emission.

[0075] (2-2. Specific Example of the Embodiment) Next, the distance measurement operation according to the embodiment will be described in more detail.

[0076] 12 is a schematic diagram illustrating an example of division of the light receiving region 12 according to the embodiment. In the example of Fig. 12, as shown in section (a), one light emitting region 22 is set for the light emitting surface 20. Sections (b) and (c) each show an example of the light receiving region 12 in the pixel array unit 100 corresponding to the light emitting region 22 shown in section (a).

[0077] In Figure 12, section (b) schematically shows a first example of division. In this first example of division, the light receiving region 12 is divided into three regions in one direction (the column direction in this example) of a two-dimensional lattice in the pixel arrangement of the pixel array unit 100, and each of the three divided regions (1) to (3) is set as a readout region 13. The readout regions 13 are set sequentially, such as region (1), region (2), and region (3), for each light emission of the light emitting region 22 one or more times. The order in which the regions (1) to (3) are set as readout regions 13 is not limited to region (1), region (2), and region (3).

[0078] In FIG. 12 , section (c) schematically illustrates a second example of division. In this second example, the light receiving region 12 is divided into six regions by dividing it into three regions in a first direction (the column direction in this example) of the two-dimensional lattice in the pixel arrangement of the pixel array unit 100 and into two regions in a second direction (the row direction in this example), and each of the six regions (1) to (6) is set as a readout region 13. The readout regions 13 are set sequentially in the column direction on the left side for one or more light emission of the light emitting region 22, such as region (1), region (2), and region (3), and then region (4), region (5), and region (6) on the right side. The order in which the regions (1) to (6) are set as readout regions 13 is not limited to region (1), region (2), region (3), region (4), region (5), and region (6).

[0079] The light-emitting region 22 is swept in units of the size of the light-emitting region 22 and sequentially moved within the light-emitting surface 20. The light-receiving region 12 is also sequentially moved in accordance with the movement of the light-emitting region 22. The readout region 13 is sequentially set within the light-receiving region 12 while maintaining the relative positional relationship.

[0080] FIG. 13 is a schematic diagram showing an example in which a plurality of light-emitting regions 22 that emit light simultaneously are set on a light-emitting surface 20 according to the embodiment.

[0081] 13, as shown in section (a), two light-emitting areas 22 that emit light simultaneously are set on light-emitting surface 20. More specifically, light-emitting surface 20 is equally divided into two areas 25 and 25 in the row direction, and light-emitting areas 22 and 22 are set in areas 25 and 25, respectively.

[0082] 13, section (b) is an example in which the first division example described in section (b) of FIG. 12 is applied to an example in which two light-emitting regions 22 and 22 are set on light-emitting surface 20. In the example of section (b) of FIG. 13, light-receiving region 12 corresponding to light-emitting region 22 in region 110 of pixel array unit 100 corresponding to region 25 on light-emitting surface 20 is divided into three in the column direction, and the three divided regions (1) to (3) are each set as readout regions 13. Similarly, light-receiving region 12 corresponding to light-emitting region 22 in region 110 of pixel array unit 100 corresponding to region 25 on light-emitting surface 20 is divided into three in the column direction, and the three divided regions (1) to (3) are each set as readout regions 13.

[0083] 13 , section (c) is an example in which the second division example described in section (c) of FIG. 12 is applied to an example in which two light-emitting regions 22 and 22 are set on light-emitting surface 20. In the example of section (c) of FIG. 13 , in region 110 of pixel array unit 100 corresponding to region 25 on light-emitting surface 20, light-receiving region 12 corresponding to light-emitting region 22 is divided into three in the column direction and two in the row direction, thereby dividing it into six, and each of the six divided regions (1) to (6) is used as readout regions 13. Similarly, in region 110 of pixel array unit 100 corresponding to region 25 on light-emitting surface 20, light-receiving region 12 corresponding to light-emitting region 22 is divided into three in the column direction and two in the row direction, thereby dividing it into six, and each of the six divided regions (1) to (6) is used as readout regions 13.

[0084] The light-emitting regions 22 and 22 emit light simultaneously. In both examples of sections (b) and (c) of FIG. 13, pixel signal readout is performed simultaneously in the readout regions 13 of the light-receiving regions 12 and 12. As an example, in the example of section (b) of FIG. 13, if region (1) in each of the light-receiving regions 12 and 12 is set as the readout region 13, readout from region (1) in the light-receiving region 12 and readout from region (1) in the light-receiving region 12 are performed simultaneously (in parallel). Similarly, in the example of section (c) of FIG. 13, if region (4) in each of the light-receiving regions 12 and 12 is set as the readout region 13, readout from region (4) in the light-receiving region 12 and readout from region (4) in the light-receiving region 12 are performed simultaneously (in parallel).

[0085] In this case as well, light-emitting areas 22 and 22 are swept in units of the size of each light-emitting area 22 and 22, and are sequentially moved within areas 25 and 25. Light-receiving areas 12 and 12 are also sequentially moved in accordance with the movement of light-emitting areas 22 and 22. Readout areas 13 are sequentially set within light-receiving areas 12 and 12, while maintaining the relative positional relationship.

[0086] Here, the relationship between the light receiving region 12 and the readout region 13 will be described. The light receiving region 12 has a size of M pixels in the vertical (column) direction and N pixels in the horizontal (row) direction, with the number of pixels being N x M. The readout region 13 has a size of (N / X) pixels in the vertical direction and (M / Y) pixels in the horizontal direction, and the number of pixels simultaneously read out in the readout region 13 is (N / X) x (M / Y). Here, M, N, X, and Y are each integers equal to or greater than 1, and satisfy the relationship N≧X and M≧Y. Note that in the light receiving region 12, adjacent readout regions 13 may partially overlap.

[0087] (More Specific Description of Processing According to the Embodiment) Next, the processing according to the embodiment will be described in more detail. Processing according to the embodiment when there is one light-emitting area 22 will be described with reference to FIGS.

[0088] As described above, in the embodiment, the readout region 13 in the light-receiving region 12 is changed for each one or more light emissions in the light-emitting region 22. In the following description, for the sake of explanation, the light-receiving region 12 is divided into two regions in the column direction, and each region is referred to as a readout region 13, and the pixel signals in the light-receiving region 12 are read out twice.

[0089] Fig. 14 is a schematic diagram showing an example in which one light-emitting region 22 is set for the light-emitting surface 20 according to the embodiment. As shown in the left diagram of Fig. 14 , one light-emitting region 22 is set for the light-emitting surface 20. The right diagram of Fig. 14 shows an example of a light-receiving region 12 in the pixel array unit 100 for the light-emitting region 22.

[0090] 15 is a schematic diagram showing an example of a case where the readout region 13 in the light-receiving region 12 is changed for each light emission of the light-emitting region 22 according to the embodiment. As shown in section (a) of FIG. 15 , for the first (nth) light emission of the light-emitting region 22, for example, the light-receiving region 12 is divided into two regions in the column direction, and the lower region of each of the two regions is set as the readout region 13, and pixel signals are read out from the readout region 13. Next, for the second (n+1th) light emission of the light-emitting region 22, as shown in section (b) of FIG. 15 , the light-receiving region 12 is divided into two regions in the column direction, and the upper region of each of the two regions is set as the readout region 13, and pixel signals are read out from the readout region 13.

[0091] When the readout of pixel signals from all readout regions 13 of the light-receiving region 12 is completed, the light-emitting region 22 is moved to the next region. The light-receiving region 12 is also moved in conjunction with the movement of the light-emitting region 22, and in the same manner as described above, pixel signals are read out from a different readout region 13 each time the light-emitting region 22 emits light.

[0092] FIG. 16 is a schematic diagram illustrating an example of an embodiment in which the readout region 13 in the light-receiving region 12 is changed for each of multiple (n) light emissions of the light-emitting region 22. As shown in section (a) of FIG. 16 , for each of the first to nth light emissions of the light-emitting region 22, the light-receiving region 12 is divided into two regions in the column direction, and the lower region of each region is set as the readout region 13, and pixel signals are read out from the readout region 13. That is, readout from the same readout region 13 is performed n times. Next, for the (n+1)th to 2nth light emissions of the light-emitting region 22, the light-receiving region 12 is divided into two regions in the column direction, and the upper region of each region is set as the readout region 13, and pixel signals are read out from the readout region 13. That is, readout from the same readout region 13 is performed n times in this case as well.

[0093] When the light-emitting region 22 has emitted light a predetermined number of times at the same position and has read out pixel signals from all readout regions 13 of the light-receiving region 12, the light-emitting region 22 is moved to the next region. The light-receiving region 12 also moves as the light-emitting region 22 moves, and in the same manner as described above, pixel signals are read out from different readout regions 13 for each of the multiple light-emitting cycles of the light-emitting region 22.

[0094] In this way, by reading out pixel signals in the same readout area 13 for multiple light emission from the same light-emitting area 22, the number of integrations required to generate a histogram increases, enabling more accurate distance measurement.

[0095] 17 is a schematic diagram illustrating another example of the embodiment in which the readout area 13 in the light receiving area 12 is changed for each of multiple light emission cycles of the light emitting area 22. In the example of FIG. 17, for the sake of explanation, light emission is performed four times in the same light emitting area 22.

[0096] As shown in sections (a) to (d) of Figure 17, on the light-emitting surface 20, the same light-emitting area 22 emits light for the first to fourth light emissions, and in the pixel array section 100, the same light-receiving area 12 is used for the first to fourth light emissions, corresponding to the light-emitting area 22.

[0097] On the other hand, the readout area 13 is different for each light emission of the light-emitting area 22. In the example of Fig. 17, at the first light emission, the lower side of the light-receiving area 12 is set as the readout area 13 (section (a)), and at the second light emission, the upper side of the light-receiving area 12 is set as the readout area 13 (section (b)). At the third light emission, the lower side of the light-receiving area 12 is again set as the readout area 13 (section (c)), and at the fourth light emission, the upper side of the light-receiving area 12 is again set as the readout area 13 (section (c)).

[0098] In the example of FIG. 17, the distance measurement processing unit 101 performs integration based on pixel signals read out from the readout area 13 at the same position in the light receiving area 12, and generates a histogram.

[0099] Fig. 18 is a schematic diagram showing an example of a method for dividing the light receiving region 12 applicable to the embodiment. For the purpose of explanation, Fig. 18 shows an example of the light receiving region 12 in which the light emitting surface 20 is divided into three in the column direction and three in the row direction.

[0100] 18 , section (a) shows an example in which the light receiving region 12 is divided into two in the column direction, and each region is used as the readout region 13. This example is not limiting, and as shown in section (b), the light receiving region 12 may be divided into two in the row direction, and each region may be used as the readout region 13, or as shown in section (c), the light receiving region 12 may be divided into two in both the column direction and the row direction, and each region may be used as the readout region 13.

[0101] Furthermore, the number of divisions of the light receiving region 12 is not limited to 2. That is, the readout region 13 may be a region in which the light receiving region 12 is divided into three or more regions in the column direction, or may be a region in which the light receiving region 12 is divided into three or more regions in the row direction. Furthermore, the readout region 13 may be a region in which the light receiving region 12 is divided into three or more regions in both the column direction and the row direction.

[0102] Even when the light receiving area 12 is divided into two or more areas in the column direction or row direction, or when the light receiving area 12 is divided into two or more areas in each of the rows and columns, and each area is used as the readout area 13, a different area may be used for one or more light emission of the light emitting area 22, as described above. Also in this case, the ranging processing unit 101 may perform integration based on pixel signals read out from the same readout area 13 in the same light receiving area 12 to generate a histogram.

[0103] (2-3. Example of Sweeping the Light-Emitting Region) Next, setting of the readout region 13 when sweeping the light-emitting region 22 within the light-emitting surface 20 according to the embodiment will be described.

[0104] (First method of setting readout area) Fig. 19 is a schematic diagram for explaining a first method of setting readout area 13 when light-emitting area 22 is swept within light-emitting surface 20 according to an embodiment. The example in Fig. 19 corresponds to the example in Fig. 15 described above. In Fig. 19, section (a) shows an example of sweeping light-emitting area 22, and section (b) shows an example of setting readout area 13 in accordance with the sweeping light-emitting area 22.

[0105] In the example of FIG. 19, as shown in section (a), the light emitting area 22 is 11 , 22 12 , 22 13 , . . . according to the size of the light emitting area 22, 11 , 22 12 , 22 13 , ... are emitted three times. 11 Then, light emission (1) to (3) is performed three times in the light emission area 22 12 Then, light emission (4) to (6) are performed three times in the light emission area 22 13 In this example, the light is emitted three times, from (7) to (9).

[0106] As shown in section (b) of FIG. 19, the light receiving area 12 is a light emitting area 22 11 , 22 12 , 22 13 , . . . the light receiving area 12 11 , 12 12 , 1213 , . . . , and each light receiving area 12 11 , 12 12 , 12 13 , . . . , the corresponding light emitting areas 22 11 , 22 12 , 22 13 , . . . , the readout areas 13 are set.

[0107] For example, the light receiving area 12 11 Now, the light receiving area 12 11 is the light emitting area 22 11 The light emitting area 22 is divided into three areas (1) to (3) according to the three light emissions. 11 For each light emission, the areas (1) to (3) are sequentially set as the readout area 13. 12 The light receiving area 12 corresponding to 12 Now, light emitting area 22 12 In response to the three light emissions, the areas (4) to (6) are sequentially set in the readout area 13, and the light emitting area 22 13 The light receiving area 12 corresponding to 13 Now, light emitting area 22 13 In response to the three light emissions, the areas (7) to (9) are set in the read area 13 in order.

[0108] 20 is a schematic diagram for more specifically explaining a first setting method of the readout area 13 when the light-emitting area 22 is swept within the light-emitting surface 20 according to the embodiment. For the sake of explanation, in FIG. 20 , the light-emitting surface 20 is divided into three parts in the column direction and the row direction, and the three light-emitting areas 22 are swept in the column direction in the bottom row. Furthermore, the light-receiving area 12 is divided into two parts in the column direction, and each of the upper and lower areas is set as the readout area 13.

[0109] As shown in the left diagram of section (a) in FIG. 20, the light emitting region 22 21 As shown in the right diagram, the first light emission occurs in the light emitting region 22 in the pixel array section 100. 21 The light receiving area 12 corresponding to 21 20, the lower area is set as the read area 13. Next, as shown in the left diagram of section (b) in FIG.21 The second light emission is performed at , and as shown in the right diagram, 21 The upper area is set as the read area 13 .

[0110] Next, as shown in the left diagram of section (c) in FIG. 20, the light emitting area 22 is swept to 22 The light emitting area 22 22 The third light emission occurs at , and as shown in the right diagram, the light emitting region 22 in the pixel array section 100 22 The light receiving area 12 corresponding to 22 20, the lower area is set as the readout area 13. Next, as shown in the left diagram of section (d) in FIG. 22 The fourth light emission is performed at , and as shown in the right diagram, 22 The upper area is set as the read area 13 .

[0111] Furthermore, as shown in the left diagram of section (e) in FIG. 20, the light emitting area 22 is swept to 23 The light emitting area 22 23 The fifth light emission occurs at , and as shown in the right diagram, the light emitting region 22 in the pixel array section 100 23 The light receiving area 12 corresponding to ２３ 20, the lower area is set as the readout area 13. Next, as shown in the left diagram of section (f) in FIG. 23 The sixth light emission is performed at , and as shown in the right diagram, 23 The upper area is set as the read area 13 .

[0112] Light receiving area 12 23 When the readout by the upper readout area 13 is completed, the light emitting area 22 is swept in the column direction. 21 After that, the light-emitting area 22 is swept and the readout area 13 in the light-receiving area 12 is set in the same manner as described above.

[0113] (Second method of setting readout area) Fig. 21 is a schematic diagram for explaining a second method of setting readout area 13 when light-emitting area 22 is swept within light-emitting surface 20 according to an embodiment. The example shown in Fig. 21 corresponds to the example of Fig. 16 described above. In Fig. 21 , section (a) shows an example of sweeping light-emitting area 22, and section (b) shows an example of setting readout area 13 in accordance with the sweeping light-emitting area 22.

[0114] In the example of FIG. 21, as shown in section (a), the light emitting area 22 is 31 , 22 32 , 22 33 , . . . according to the size of the light emitting area 22, 31 , 22 32 , 22 33 , ...., each light emitting area 22 31 Light emission (1), light emitting area 22 32 Light emission (2), light emitting area 22 33 In the example shown in FIG. 1, light emission (3) is performed once.

[0115] As shown in section (b) of FIG. 21, the light receiving area 12 is 31 , 22 32 , 22 33 , . . . the light receiving area 12 31 , 12 32 , 12 33 , .... Each light receiving area 12 31 , 12 32 , 12 33 , . . . , the corresponding light emitting areas 22 31 , 22 32 , 22 33 , . . . , one of the three divided regions is set as the readout region 13.

[0116] As an example, the light receiving area 12 31 , 12 32 , 12 33 , ... are each divided into three in the column direction. 31 , 12 32 , 12 33 , ... are light emitting areas 2231 , 22 32 , 22 33 , ... In response to each light emission, the bottom regions (1) to (3) are set as readout regions 13. When the readout of the bottom regions (1) to (3) is completed, the light emitting region 22 is set again. 31 , 22 32 , 22 33 , . . . are emitted sequentially, and each light receiving area 12 31 , 12 32 , 12 33 , . . . , each area immediately above the bottom area (1) to (3) is set as the read area 13.

[0117] 22 is a schematic diagram for more specifically explaining a second setting method of the readout area 13 according to the embodiment when the light-emitting area 22 is swept within the light-emitting surface 20. For the sake of explanation, in FIG. 22 , similar to the above-described FIG. 20 , the light-emitting surface 20 is divided into three parts in the column direction and three parts in the row direction, and the three light-emitting areas 22 are swept in the column direction in the bottom row. Furthermore, the light-receiving area 12 is divided into two parts in the column direction, and each of the upper and lower areas is set as the readout area 13.

[0118] As shown in the left diagram of section (a) in FIG. 22, the light emitting region 22 41 As shown in the right diagram, the first light emission occurs in the light emitting region 22 in the pixel array section 100. 41 The light receiving area 12 corresponding to 41 22, the lower area is set as the readout area 13. Next, as shown in the left diagram of section (b) in FIG. 22, the light emitting area 22 is swept to 42 The light emitting area 22 42 The second light emission is performed at , and as shown in the right diagram, 42 22, the lower area is set as the readout area 13. Then, as shown in the left diagram of section (c) in FIG. 22, the light emitting area 22 is swept to 43 The light emitting area 22 43The third light emission occurs at , and as shown in the right diagram, the light emitting region 22 in the pixel array section 100 33 The light receiving area 12 corresponding to 43 The lower area is set as the read area 13.

[0119] Each light receiving area 12 41 ~12 43 When the reading by the reading area 13 set in the lower area is completed, the light emitting area 22 41 Light emission starts from each light receiving area 12 41 ~12 43 , the upper area is the read area 13 .

[0120] Specifically, as shown in the left diagram of section (d) in FIG. 22, the light emitting region 22 41 The fourth light emission is performed at , and as shown in the right diagram, 41 22, the upper area is set as the read area 13. Next, as shown in the left diagram of section (e) in FIG. 22, the light emitting area 22 is swept to 42 The light emitting area 22 32 The fifth light emission occurs at , and as shown in the right diagram, the light emitting region 22 in the pixel array section 100 42 The light receiving area 12 corresponding to 42 22, the lower area is set as the readout area 13. Next, as shown in the left diagram of section (f) in FIG. 43 The sixth light emission is performed at , and as shown in the right diagram, 43 The upper area is set as the read area 13 .

[0121] Light receiving area 12 43 When the readout by the upper readout area 13 is completed, the light emitting area 22 is swept in the column direction. 41 After that, the light-emitting area 22 is swept and the readout area 13 in the light-receiving area 12 is set in the same manner as described above.

[0122] As described above, in the embodiment of the present disclosure, in the light receiving region corresponding to the light emitting region, each divided region of the light receiving region is used as a readout region for reading out pixel signals. Furthermore, in the embodiment, a different readout region is used for each light emission of the light emitting region. Therefore, by applying the embodiment of the present disclosure, pixel signals can be read out in the light receiving region without excess or deficiency. This allows for efficient distance measurement, reduced power consumption, and improved frame rate.

[0123] Patent Document 1 discloses a technology for selecting readout pixels that read pixel signals based on count results in a photon count sensor. However, the gist of this technology differs from that of the technology disclosed herein in terms of setting an optimal readout area for a light-receiving area. Patent Document 2 also discloses a method for setting a region of interest (ROI) in a sensor that directly performs ToF using a SPAD. Patent Document 2 describes a technology for setting an ROI by selecting rows and then columns, but does not describe the control of the size of the readout area according to the laser spot system (light-emitting area) disclosed herein.

[0124] (3. Application Examples of the Embodiments of the Present Disclosure) Next, application examples of the embodiments of the present disclosure will be described.

[0125] (Application Example to a Moving Body) The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0126] FIG. 23 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0127] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 23, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (Interface) 12053.

[0128] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0129] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0130] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0131] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0132] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0133] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the distance between vehicles, maintaining vehicle speed, vehicle collision warning, vehicle lane departure warning, etc.

[0134] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0135] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0136] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 23, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0137] FIG. 24 is a diagram showing an example of the installation position of the imaging unit 12031.

[0138] In FIG. 24, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0139] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided on the top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0140] 24 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0141] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0142] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation.

[0143] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0144] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0145] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the imaging unit 12031 among the above-described configurations. Specifically, the distance measuring device 1 according to an embodiment of the present disclosure can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, it is possible to reduce battery consumption when measuring short and long distances, and by improving the frame rate, it is possible to obtain more accurate distance measurement information, thereby providing a safer driving environment for the driver.

[0146] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0147] Note that the present technology can also be configured as follows: (1) A photodetector including a light-receiving unit having a light-receiving surface on which pixels that generate pixel signals in response to irradiated light are arranged in a two-dimensional lattice array, a control unit that controls reading of the pixel signals generated in the light-receiving unit and light emission of light-emitting points in a light source unit having a light-emitting surface on which light-emitting points are arranged in a two-dimensional lattice array, and a generation unit that classifies and integrates the pixel signals read out from the light-receiving unit based on the time from the light emission timing in the light source unit to the readout timing of the pixel signals in the light-receiving unit to generate a histogram, wherein the control unit causes the light-emitting points included in light-emitting regions obtained by dividing the light-emitting surface to emit light, and reads out the pixel signals from the pixels in a readout region that is smaller than the light-receiving region and is included in a light-receiving surface corresponding to the light-emitting region. (2) The photodetector according to (1), wherein the control unit sets one of the divided regions obtained by dividing the light-receiving region as the readout region. (3) The photodetector according to (2), wherein the control unit sets different readout regions in the light-receiving region for each light emission from the same light-emitting region one or more times. (4) The photodetector according to (2) or (3), wherein the control unit sets the same readout region in the light-receiving region for each light emission from a different light-emitting region. (5) The photodetector according to (2), wherein the control unit divides the light-receiving region in one direction of the two-dimensional lattice to generate the divided regions. (6) The photodetector according to (2), wherein the control unit divides the light-receiving region in each of two directions of the two-dimensional lattice to generate the divided regions. (7) The photodetector according to any one of (2) to (6), wherein the control unit sets a plurality of the light-receiving regions on the light-receiving surface corresponding to a plurality of the light-emitting regions that are set on the light-emitting surface and that are caused to emit light simultaneously. (8) The photodetection device according to any one of (1) to (7), wherein the generation unit generates the histogram by integrating the pixel signals read out from the same readout region.(9) The photodetector according to any one of (1) to (8), wherein the light receiving unit has the pixel formed by an avalanche photodiode and a pulse conversion circuit that converts the output of the avalanche photodiode into a pulse to generate the pixel signal. (10) The photodetector according to (9), wherein the light receiving unit operates the avalanche photodiode in Geiger mode. (11) The photodetector according to any one of (1) to (10), wherein the light receiving unit detects reflected light from an object and acquires environmental information. (12) The photodetector according to (11), wherein the environmental information includes a distance to the object, a reflectance of the object, and ambient light. (13) A distance measuring device comprising: a light receiving unit having a light receiving surface on which pixels that generate pixel signals according to irradiated light are arranged in a two-dimensional lattice array; a control unit that controls reading of the pixel signals generated in the light receiving unit and light emission of light emitting points in a light source unit having a light emitting surface on which light emitting points are arranged in a two-dimensional lattice array; a generation unit that classifies and accumulates the pixel signals read out from the light receiving unit based on the time from the light emission timing in the light source unit to the readout timing of the pixel signals in the light receiving unit to generate a histogram; and a distance measuring unit that measures the distance to an object based on the histogram, wherein the control unit causes the light emitting points included in light emitting areas obtained by dividing the light emitting surface to emit light, and reads out the pixel signals from the pixels of a readout area that is smaller than the light receiving area and is included in a light receiving area on the light receiving surface that corresponds to the light emitting area.

[0148] 1 Range finding device 2 Light source unit 10, 101, 102, 103, 104 Pixel 11 Macro pixel 12, 121, 122, 123, 124, 12 11 , 12 12 , 12 13 , 12 21 , 12 22 , 12 23 , 12 31 , 12 32 , 12 33 Light receiving area 13 Readout area 20 Light emitting surface 21 Light emitting points 22, 221, 222, 223, 224, 22 11 , 2212 , 22 13 , 22 21 , 22 22 , 22 23 , 22 31 , 22 32 , 22 33 Light-emitting region 100 Pixel array unit 101 Distance measurement processing unit 103 Overall control unit 110 Conversion unit 111 Generation unit 112 Signal processing unit 330 Histogram 1000 Light receiving element

Claims

1. A photodetection device comprising: a light receiving unit having a light receiving surface in which pixels that generate pixel signals in response to irradiated light are arranged in a two-dimensional lattice array; a control unit that controls the reading of the pixel signals generated in the light receiving unit and the emission of the light emitting points in a light source unit having a light emitting surface in which the light emitting points are arranged in a two-dimensional lattice array; and a generation unit that classifies and accumulates the pixel signals read out from the light receiving unit based on the time from the emission timing in the light source unit to the readout timing of the pixel signals in the light receiving unit to generate a histogram, wherein the control unit causes the light emitting points included in light emitting regions obtained by dividing the light emitting surface to emit light, and reads out the pixel signals from the pixels in a readout region that is smaller than the light receiving region and is included in a light receiving region on the light receiving surface that corresponds to the light emitting region.

2. The photodetector according to claim 1, wherein the control unit sets one of the divided areas obtained by dividing the light receiving area as the readout area.

3. The optical detection device according to claim 2, wherein the control unit sets a different readout area within the light receiving area for each one or more light emissions from the same light emitting area.

4. The photodetector according to claim 2, wherein the control unit sets the same readout area within the light-receiving area for each light emission from a different light-emitting area.

5. The photodetector according to claim 2, wherein the control unit generates the divided regions by dividing the light receiving region in one direction of the two-dimensional lattice.

6. The photodetector according to claim 2, wherein the control unit generates the divided regions by dividing the light receiving region in each of two directions of the two-dimensional lattice.

7. The optical detection device according to claim 2, wherein the control unit sets a plurality of light receiving areas on the light receiving surface corresponding to a plurality of light emitting areas that are set on the light emitting surface and that emit light simultaneously.

8. The photodetection device according to claim 1, wherein the generation section generates the histogram by accumulating the pixel signals read out from the same readout region.

9. The photodetector according to claim 1, wherein the light receiving section comprises: the pixel formed by an avalanche photodiode; and a pulse conversion circuit that converts the output of the avalanche photodiode into a pulse to generate the pixel signal.

10. The photodetector according to claim 9, wherein the light receiving section operates the avalanche photodiode in Geiger mode.

11. The optical detection device according to claim 1, wherein the light receiving unit detects reflected light from an object and acquires environmental information.

12. The optical detection device according to claim 11, wherein the environmental information includes a distance to the object, a reflectance of the object, and ambient light.

13. A distance measuring device comprising: a light receiving unit having a light receiving surface in which pixels that generate pixel signals in response to irradiated light are arranged in a two-dimensional lattice array; a control unit that controls reading out the pixel signals generated in the light receiving unit and lighting of light emitting points in a light source unit having a light emitting surface in which light emitting points are arranged in a two-dimensional lattice array; a generation unit that classifies and accumulates the pixel signals read out from the light receiving unit based on the time from the light emission timing in the light source unit to the readout timing of the pixel signals in the light receiving unit to generate a histogram; and a distance measuring unit that measures the distance to an object based on the histogram, wherein the control unit causes the light emitting points included in light emitting areas divided into the light emitting surface to emit light, and reads out the pixel signals from the pixels in a readout area smaller than the light receiving area that is included in a light receiving area on the light receiving surface corresponding to the light emitting area.

Images