Distance measuring device

Abstract

To provide a distance measuring device that can reduce omission of information on incident light.SOLUTION: A distance measuring device has: a time counting unit that outputs a time count value indicating the time elapsed from when time count is started; a receiving unit that has a plurality of pixels and outputs a light reception count value of incident light on each of the plurality of pixels; and a pixel information generation unit that outputs pixel information in which the light reception count value and the time count value are associated with each other for every pixel. The pixel information generation unit acquires the light reception count value of each of the plurality of pixels within a period of time equal to or less than the time required for the time count value to change by a predetermined value and outputs the pixel information of each of the plurality of pixels.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a distance measuring device. [Background technology]

[0002] Patent Document 1 discloses a distance measuring device that measures the distance to an object based on the flight time of light from when a light source emits light until a pixel receives the reflected light from the object. The distance measuring device in Patent Document 1 has a time-to-digital converter to which signals from multiple pixels are input, and a correction processing unit that corrects the delay time using a correction value corresponding to the position of the pixel.

[0003] Patent Document 2 discloses a distance measuring device in which multiple photodetectors and corresponding multiple registers are arranged. Each of the multiple registers holds data indicating the position of the register when incident light is detected. The multiple registers are linked to form a shift register. Data is read out by shifting the data in each register to the register with the address one position to the right every time a predetermined time has passed. The actual photon arrival time is calculated from the difference between the time when the data moves to the rightmost address and the time when the data is shifted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 022137 [Patent Document 2] Special Publication No. 2020-524258 Summary of the Invention [Problem to be solved by the invention]

[0005] In distance measuring devices having a configuration in which a time count unit is shared by multiple pixels as in Patent Documents 1 and 2, if light is incident on a pixel during a period in which a signal is being read out, information on the incident light may be lost. Therefore, there is a demand for reducing loss of information on the incident light.

[0006] An object of the present invention is to provide a distance measuring device capable of reducing loss of information about incident light. [Means for solving the problem]

[0007] According to one disclosure of this specification, there is provided a distance measuring device comprising: a time counting unit that outputs a time count value indicating the elapsed time since time counting began; a light receiving unit having a plurality of pixels and outputting a light reception count value of light incident on each of the plurality of pixels; and a pixel information generating unit that outputs pixel information in which the light reception count value and the time count value correspond to each pixel, wherein the pixel information generating unit acquires the light reception count value of each of the plurality of pixels within a period of time less than the time in which the time count value changes by a predetermined value, and outputs the pixel information of each of the plurality of pixels. Effect of the Invention

[0008] According to the present invention, there is provided a distance measuring device capable of reducing loss of information on incident light. [Brief description of the drawings]

[0009] [Figure 1] 1 is a hardware block diagram showing an example of a schematic configuration of a distance measuring device according to a first embodiment. [Diagram 2] 1 is a functional block diagram showing a schematic configuration example of a distance measuring device according to a first embodiment. [Diagram 3] 2 is a diagram showing an outline of the operation of the distance measuring device according to the first embodiment in one distance measuring period. FIG. [Figure 4] 4 is a histogram visually showing a frequency distribution of pulse count values ​​according to the first embodiment. [Diagram 5]2 is a diagram showing configurations of a light receiving unit, a control unit, a time counting unit, and a pixel information generating unit according to the first embodiment. FIG. [Figure 6] 1 is a diagram showing the configuration and operation of a pixel according to a first embodiment; [Figure 7] 4 is a timing chart showing the operation of the distance measuring device according to the first embodiment. [Figure 8] 13 is a diagram showing configurations of a light receiving section, a control section, a time counting section, and a pixel information generating section according to a second embodiment. FIG. [Figure 9] 10 is a timing chart showing the operation of the distance measuring device according to the second embodiment. [Figure 10] 13 is a diagram showing configurations of a light receiving unit, a control unit, a time count unit, and a pixel information generation unit according to a third embodiment. FIG. [Figure 11] FIG. 13 is a diagram showing configurations of a light receiving section, a control section, a time counting section, and a pixel information generating section according to the fourth embodiment. [Figure 12] FIG. 13 is a diagram showing configurations of a light receiving section, a control section, a time counting section, and a pixel information generating section according to the fifth embodiment. [Figure 13] FIG. 13 is a diagram showing configurations of a light receiving unit, a control unit, a time counting unit, and a pixel information generating unit according to a sixth embodiment. [Figure 14] FIG. 13 is a schematic diagram of a device according to a seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The same elements or corresponding elements in multiple drawings are denoted by the same reference numerals, and the description thereof may be omitted or simplified.

[0011] [First embodiment] 1 is a hardware block diagram showing a schematic configuration example of a distance measuring device 1 according to this embodiment. The distance measuring device 1 has a light emitting device 3, a light receiving device 4, and a signal processing circuit 5. Note that the configuration of the distance measuring device 1 shown in this embodiment is just an example, and is not limited to the configuration shown in the figure.

[0012] The distance measuring device 1 is a device that measures the distance to the object 2 to be measured using technology such as LiDAR (Light Detection And Ranging). The distance measuring device 1 measures the distance from the distance measuring device 1 to the object 2 based on the time difference between when light is emitted from the light emitting device 3, when it is reflected by the object 2, and when it is received by the light receiving device 4, that is, the time of flight (ToF) of light.

[0013] One of the measurement methods used in LiDAR is the direct time of flight (dToF) method, which directly measures the time elapsed from light emission to light reception using a time-to-digital converter or the like, and calculates distance from the elapsed time and the speed of light.

[0014] There are three light emission methods used for distance measurement using the dToF method: the Scan method, the Sequential Flash method, and the Flash method. The Scan method is a method in which light is irradiated onto one point in the distance measurement area to perform distance measurement, and this process is repeated while shifting the irradiation position within the distance measurement area. The Sequential Flash method is a method in which light is irradiated onto a portion of the distance measurement area to perform distance measurement, and this process is repeated while shifting the irradiation range within the distance measurement area. The Flash method is a method in which light is irradiated onto the entire distance measurement area at once, and the reflected light is received by a pixel array to perform distance measurement.

[0015] The light received by the light receiving device 4 includes ambient light such as sunlight in addition to the reflected light from the target object 2. Therefore, the distance measuring device 1 measures the light incident during each of a plurality of periods (bin periods) and determines that the reflected light is incident during the period when the amount of light is at its peak, thereby performing distance measurement with reduced influence of ambient light.

[0016] The light emitting device 3 is a device such as a semiconductor laser that emits light such as laser light to the outside of the distance measuring device 1. If the distance measuring device 1 operates using a scan method, the light emitting device 3 may be a point light source. If the distance measuring device 1 operates using a sequential flash method, the light emitting device 3 may be a line light source or a pattern light source. If the distance measuring device 1 operates using a flash method, the light emitting device 3 may be a surface light source.

[0017] The signal processing circuit 5 may include a control circuit, a counter circuit, a processor that performs arithmetic processing of digital signals, a memory that stores digital signals, etc. The memory may be, for example, a semiconductor memory.

[0018] The light receiving device 4 generates a pulse signal including a pulse based on the incident light, and counts the pulse signal to generate a light receiving count value. The light receiving device 4 is, for example, a photoelectric conversion device including an avalanche photodiode as a photoelectric conversion element. In this case, when one photon is incident on the avalanche photodiode and an electric charge is generated, one pulse is generated by avalanche multiplication. However, the light receiving device 4 may be, for example, a photoelectric conversion element using another photodiode.

[0019] In the Sequential Flash method and the Flash method, reflected light is detected simultaneously by multiple pixels. In the Scan method, reflected light may also be detected simultaneously by multiple pixels to improve accuracy. The light receiving device 4 of this embodiment includes multiple pixels to make these methods applicable.

[0020] Fig. 2 is a functional block diagram showing an example of a schematic configuration of a distance measuring device 1 according to this embodiment. The distance measuring device 1 has a light emitting unit 11, a light receiving unit 12, a control unit 13, a time counting unit 14, a pixel information generating unit 15, a frequency distribution generating unit 16, a distance calculating unit 17, and an output unit 18. The light emitting unit 11 and the light receiving unit 12 correspond to the light emitting device 3 and the light receiving device 4 in Fig. 1, respectively. The control unit 13, the time counting unit 14, the pixel information generating unit 15, the frequency distribution generating unit 16, the distance calculating unit 17, and the output unit 18 correspond to the signal processing circuit 5 in Fig. 1.

[0021] The control unit 13 controls the light emission timing of the light emitting unit 11. The control unit 13 also has a function of outputting a clock signal to the light receiving unit 12, the time counting unit 14, and the pixel information generating unit 15.

[0022] The time count unit 14 performs time counting under the control of the control unit 13, thereby generating the elapsed time from the start of the time counting as a time count value, and outputs it to the pixel information generation unit 15. The control unit 13 controls the synchronization between the light emission timing and the start timing of the time counting in the time count unit 14. This allows the time count unit 14 to count the elapsed time from the light emission in the light emission unit 11. The time count unit 14 includes circuits such as a ring oscillator and a counter, and performs time counting by counting a clock signal that oscillates at high speed and with a constant period.

[0023] The control unit 13 also performs overall control of signal acquisition during one frame period in the distance measuring device 1. As a result, the distance measuring device 1 is controlled so that the light emitting unit 11 starts emitting light and the time counting unit 14 starts counting time multiple times during one frame period.

[0024] Light emitted from the light-emitting unit 11 is reflected by the object 2. The light, including the reflected light from the object 2, is received by the light-receiving unit 12. The light-receiving unit 12 converts the received light into electrical signal pulses by photoelectric conversion. These pulses are counted in the light-receiving unit 12, and a light-receiving count value is generated.

[0025] The pixel information generating unit 15 acquires the light reception count value generated by the light receiving unit 12 and the time count value output from the time counting unit 14. The pixel information generating unit 15 outputs pixel information in which the light reception count value and the time count value are associated with each other for each pixel.

[0026] The generated pixel information is accumulated in the form of a frequency distribution in the frequency distribution generating unit 16. The frequency distribution is information in which classes set at predetermined time intervals correspond to the frequency of light reception count values ​​based on incident light within a period corresponding to each class. The frequency distribution generating unit 16 includes a memory that stores the frequency distribution for each pixel. When the frequency distribution for one ranging frame is accumulated in the frequency distribution generating unit 16, the distance calculating unit 17 calculates distance information of the corresponding pixel from the frequency distribution of each pixel. The output unit 18 outputs the calculated distance information to the outside.

[0027] Fig. 3 is a diagram showing an outline of the operation of the distance measuring device 1 according to this embodiment in one distance measuring period. In the "distance measuring period" in Fig. 3, a plurality of frame periods FL1, FL2, ... FL3 included in one distance measuring period are shown. The frame period FL1 indicates the first frame period in one distance measuring period, the frame period FL2 indicates the second frame period in one distance measuring period, and the frame period FL3 indicates the final frame period in one distance measuring period. The frame period is a period during which the distance measuring device 1 performs one distance measuring and outputs once to the outside a signal indicating the distance (distance measuring result) from the distance measuring device 1 to the object 2.

[0028] The "frame period" in FIG. 3 shows multiple shots SH1, SH2, ... SH3 and a peak output POUT included in a frame period FL1. A shot is a period during which the light emitting unit 11 emits light and the frequency distribution is updated by a light receiving pulse PLS based on this light emission. Shot SH1 indicates the first shot in the frame period FL1. Shot SH2 indicates the second shot in the frame period FL1. Shot SH3 indicates the final shot in the frame period FL1. The peak output POUT indicates a period during which a distance measurement result is output based on a peak obtained by accumulating signals from multiple shots.

[0029] In FIG. 3, "shot" shows multiple bins BN1, BN2...BN3 included in shot SH1. A "bin" indicates one time interval (bin period) during which a series of pulse counts are performed. Bin BN1 indicates the first bin in shot SH1. Bin BN2 indicates the second bin in shot SH1. Bin BN3 indicates the last bin in shot SH1.

[0030] "Time count" in Fig. 3 shows a schematic diagram of a time change in a time count value generated by the time counting unit 14. As shown in Fig. 3, the time counting unit 14 counts up the count value for each time interval of a bin as time passes. Therefore, the time count value is a parameter that indicates the bin number.

[0031] "Light reception count" in Fig. 3 shows a schematic diagram of the light reception pulse PLS based on the incident light in bin BN1 and the change in the light reception count value of bin BN1. As shown in Fig. 3, when the light reception pulse PLS rises, the light reception count value counts up by 1. As a result, the number of photons detected within the bin period is acquired as the light reception count value. When one bin period elapses and the next bin period begins, the light reception count value is reset to zero.

[0032] FIG. 4(a) to FIG. 4(d) are histograms visually showing the frequency distribution generated by the frequency distribution generating unit 16. In this specification, the frequency distribution is frequency information corresponding to a predetermined class width, and does not necessarily have to be displayed visually. FIG. 4(a), FIG. 4(b), and FIG. 4(c) are example histograms of the number of photons (corresponding to the light receiving count value) in the first shot, the second shot, and the third shot, respectively. FIG. 4(d) is an example histogram of the total number of photons in all shots. The horizontal axis indicates the elapsed time from the light emission. One section of the histogram corresponds to one bin period during which photons are detected. The vertical axis indicates the number of photons detected in each bin period.

[0033] As shown in FIG. 4(a), in the first shot, photons are incident in five bin periods. As shown in FIG. 4(b), in the second shot, photons are incident in four bin periods. As shown in FIG. 4(c), in the third shot, photons are also incident in four bin periods. In this way, the number and time of incidence of photons differ in each shot. These frequency distributions may include not only the frequency of reflected light from the object 2, but also the frequency due to the light reception count value due to environmental light other than the reflected light.

[0034] As shown in Fig. 4(d), in the histogram of the accumulated photon counts of all shots, the sixth bin BN11 has the largest number of photons, so bin BN11 is the peak. In the peak output POUT in Fig. 3, time information of the bin corresponding to the peak of the frequency distribution after accumulation is output. This time information indicates the flight time of the light emitted from the light emitting unit 11 and reflected by the object 2, and can be used to calculate the distance between the distance measuring device 1 and the object 2.

[0035] By accumulating the pulse count values ​​of multiple shots, even if the pulse count value may be due to ambient light, it is possible to more accurately detect a bin that is likely to contain a pulse count value due to reflected light from the target object 2. Therefore, even if the light emitted from the light-emitting unit 11 is weak, multiple shots are repeated and a process of accumulating these shots is adopted, allowing for highly accurate distance measurement.

[0036] Next, a method for acquiring a light reception count value from the light receiving unit 12 will be described with reference to Fig. 5 to Fig. 7. Fig. 5 is a diagram showing the configurations of the light receiving unit 12, the control unit 13, the time count unit 14, and the pixel information generation unit 15 according to this embodiment. Fig. 6 is a diagram showing the configuration and operation of a pixel 120 according to this embodiment. Fig. 7 is a timing chart showing the operation of the distance measuring device 1 according to this embodiment.

[0037] As shown in FIG. 5, the light receiving unit 12 has a plurality of pixels 120, a plurality of selectors 125, and a plurality of registers 126. The plurality of selectors 125 and the plurality of registers 126 are arranged so as to correspond to the plurality of pixels 120, respectively. The number of the plurality of pixels 120, the number of the plurality of selectors 125, and the number of the plurality of registers 126 are each assumed to be N+1. In addition, in FIG. 5, for example, the pixels 120-0, 120-1, 120-2, ..., 120-N are distinguished from each other by adding a suffix number to the reference numerals of the N+1 pixels 120. In the following, when it is necessary to distinguish between a plurality of elements, the reference numerals may be given a suffix number.

[0038] The configuration and operation of one of the multiple pixels 120 will be described with reference to Figures 6(a) to 6(c). As shown in Figure 6(a), pixel 120-X (X is an integer between 0 and N) has an avalanche photodiode (APD) 121, a quenching element 122, a waveform shaping unit 123, and a counter circuit 124. Note that although only pixel 120-X is shown in Figure 6(a), the other pixels 120 have the same configuration.

[0039] The APD 121 is a photoelectric conversion element that generates electric charges according to incident light by photoelectric conversion. A voltage VL (first voltage) is supplied to an anode of the APD 121. A cathode of the APD 121 is connected to a first terminal of the quench element 122 and an input terminal of the waveform shaping unit 123. A voltage VH (second voltage) higher than the voltage VL supplied to the anode of the APD 121 is supplied to a second terminal of the quench element 122. As a result, a reverse bias voltage is supplied to the anode and cathode of the APD 121 such that the APD 121 performs an avalanche multiplication operation. When electric charges are generated by incident light in the APD 121 to which the reverse bias voltage is supplied, the electric charges cause avalanche multiplication, generating an avalanche current.

[0040] There are two operation modes when a reverse bias voltage is supplied to the APD 121: Geiger mode and linear mode. The Geiger mode is a mode in which the APD 121 operates with a potential difference between the anode and cathode that is greater than the breakdown voltage, and the linear mode is a mode in which the APD 121 operates with a potential difference between the anode and cathode that is close to or less than the breakdown voltage.

[0041] An APD operated in Geiger mode is called a SPAD (Single Photon Avalanche Diode). In this case, for example, the voltage VL (first voltage) is −30 V, and the voltage VH (second voltage) is 1 V. The APD 121 may be operated in either linear mode or Geiger mode. In the case of a SPAD, the potential difference is larger than that of an APD in linear mode, and the effect of avalanche multiplication is more pronounced, so a SPAD is preferable.

[0042] The quench element 122 functions as a load circuit (quench circuit) during signal multiplication by avalanche multiplication. The quench element 122 suppresses the voltage supplied to the APD 121 to suppress avalanche multiplication (quench operation). The quench element 122 also returns the voltage supplied to the APD 121 to the voltage VH by passing a current corresponding to the voltage drop caused by the quench operation (recharge operation). The quench element 122 may be, for example, a resistor or a transistor.

[0043] The waveform shaping unit 123 shapes the potential change of the cathode of the APD 121 obtained when a photon is detected, and outputs a pulse signal. For example, an inverter circuit is used as the waveform shaping unit 123. Although an example using one inverter as the waveform shaping unit 123 is shown in Fig. 6(a), the waveform shaping unit 123 may be a circuit in which a plurality of inverters are connected in series, or may be another circuit having a waveform shaping effect.

[0044] The counter circuit 124 counts the pulse signal output from the waveform shaping unit 123 and holds the digital signal. The counter circuit 124 also has a function of resetting the held signal when a control signal is supplied from a control circuit such as the control unit 13. The pixel 120-X can output the digital signal held in the counter circuit 124 as a light reception count value PX (any of P0, P1, ...PN).

[0045] 6(a), a connection node between the APD 121, the quench element 122, and the input terminal of the waveform shaping unit 123 is defined as node A. Also, as shown in FIG. 6(a), a connection node between the output terminal of the waveform shaping unit 123 and the counter circuit 124 is defined as node B.

[0046] FIG. 6(b) is a graph showing the time change of the potential of node A in FIG. 6(a). FIG. 6(c) is a graph showing the time change of the potential of node B in FIG. 6(a). In the period from time t0 to time t1, a voltage of VH-VL is applied to the APD 121 in FIG. 6(a). When a photon is incident on the APD 121 at time t1, avalanche multiplication occurs in the APD 121. As a result, an avalanche current flows through the quench element 122, and the potential of the node A drops. After that, the amount of potential drop further increases, and the voltage applied to the APD 121 gradually decreases. Then, at time t2, the avalanche multiplication in the APD 121 stops. As a result, the voltage level of the node A does not drop below a certain value. After that, in the period from time t2 to time t3, a current that compensates for the voltage drop flows from the node of voltage VH to the node A, and at time t3, the node A settles to the original potential.

[0047] In the above process, the potential of node B becomes high level during the period when the potential of node A is lower than a certain threshold. In this way, the waveform of the drop in the potential of node A caused by the incidence of photons is shaped by the waveform shaping unit 123 and output as a pulse to node B. The counter circuit 124 counts this pulse to generate a light reception count value PX. In this way, the distance measuring device 1 of this embodiment may include pixels 120-X that use avalanche photodiodes as photoelectric conversion elements.

[0048] The configuration of other elements of the light receiving section 12 will be described with reference to FIG. 5 again. Each of the selectors 125-0, 125-1, 125-2, ..., 125-N has a first input terminal, a second input terminal, an output terminal, and a control terminal. The signal SEL is input from the pixel information generating section 15 to the control terminals of the selectors 125-0, 125-1, 125-2, ..., 125-N. When the signal SEL is at a high level (signal value "1"), each of the selectors 125-0, 125-1, 125-2, ..., 125-N outputs a signal of the same level as the signal input to the first input terminal. When the signal SEL is at a low level (signal value "0"), each of the selectors 125-0, 125-1, 125-2, ..., 125-N outputs a signal of the same level as the signal input to the second input terminal.

[0049] The output terminals of the pixels 120-0, 120-1, 120-2, ..., 120-N are connected to the first input terminals of the selectors 125-0, 125-1, 125-2, ..., 125-N, respectively. That is, the pixels 120-0, 120-1, 120-2, ..., 120-N output the light reception count values ​​P0, P1, P2, ..., PN to the first input terminals of the selectors 125-0, 125-1, 125-2, ..., 125-N, respectively.

[0050] Each of the registers 126-0, 126-1, 126-2, ..., 126-N has an input terminal, an output terminal, and a control terminal. Each of the registers 126-0, 126-1, 126-2, ..., 126-N is a sequential circuit having a function of holding an input signal, and may include a flip-flop circuit.

[0051] A low-level signal is input to the second input terminal of the selector 125-0. The output terminal of the selector 125-0 is connected to the input terminal of the register 126-0. The output terminal of the register 126-0 is connected to the second input terminal of the selector 125-1. The output terminal of the selector 125-1 is connected to the input terminal of the register 126-1. The output terminal of the register 126-1 is connected to the second input terminal of the selector 125-2. Similarly, the selectors 125 and the registers 126 are alternately connected thereafter. The output terminal of the register 126-N is connected to the pixel information generating unit 15. The output signal of the register 126-N is the signal SR_OUT.

[0052] The control unit 13 outputs a clock signal SR_CLK to each control terminal of the registers 126-0, 126-1, 126-2, ..., 126-N and to the pixel information generating unit 15. The registers 126-0, 126-1, 126-2, ..., 126-N form a shift register. When the signal SEL is at a low level (second state), each of the registers 126-0, 126-1, 126-2, ..., 126-N holds a signal input to the input terminal at the timing when the clock signal SR_CLK rises, and continues to output the signal from the output terminal. As a result, an operation is performed in which the signal held in each stage of the register 126 is shifted to the register 126 of the next stage every time the clock signal SR_CLK rises.

[0053] When the signal SEL is at a high level (first state), the registers 126-0, 126-1, 126-2, ..., 126-N are connected to the pixels 120-0, 120-1, 120-2, ..., 120-N, respectively. At this time, the registers 126-0, 126-1, 126-2, ..., 126-N acquire and hold the light reception count values ​​P0, P1, P2, ..., PN from the pixels 120-0, 120-1, 120-2, ..., 120-N, respectively.

[0054] The time count unit 14 outputs a time count value CNT to the pixel information generation unit 15. The pixel information generation unit 15 associates the signal SR_OUT output from the register 126-N with the time count value CNT at the time when the signal SR_OUT is input, and outputs the result as pixel information OUT to the frequency distribution generation unit 16.

[0055] Fig. 7 is a timing chart showing the operation of the distance measuring device according to this embodiment. Fig. 7 shows the time changes of the time count value CNT, the clock signal SR_CLK, the signal SR_OUT, the light reception count value PX, the signal SEL, and the pixel information OUT shown in Fig. 5 or Fig. 6(a).

[0056] The time count value CNT is the value of the signal output from the time count unit 14 to the pixel information generation unit 15, and corresponds to a bin number. Fig. 7 shows a period in which the value of the time count value CNT is t and a period in which the value is (t+1).

[0057] The clock signal SR_CLK indicates a signal input to the registers 126-0, 126-1, 126-2, ... 126-N from the control unit 13. The clock signal SR_CLK is also input to the pixel information generation unit 15 and is used for synchronizing the timing of signal acquisition, etc.

[0058] The signal SR_OUT is an output signal from the register 126-N, which is the final stage of the shift register, and is input to the pixel information generating unit 15. FIG. 7 shows the value and change of the signal SR_OUT. In FIG. 7, "P0(t)" indicates the light receiving count value output from the 0th pixel 120-0 during the period when the value of the time count value CNT is t. "PN(t)" indicates the light receiving count value output from the Nth pixel 120-N during the period when the value of the time count value CNT is t. "P0(t+1)" indicates the light receiving count value output from the 0th pixel 120-0 during the period when the value of the time count value CNT is (t+1). "PN(t+1)" indicates the light receiving count value output from the Nth pixel 120-N during the period when the value of the time count value CNT is (t+1). The notations of the other values ​​of the signal SR_OUT are defined similarly.

[0059] The light receiving count value PX is a signal output from the Xth pixel 120-X. In Fig. 7, "PX(t+1)" indicates the light receiving count value corresponding to the period during which the time count value CNT is (t+1), among the light receiving count values ​​repeatedly output from the pixel 120-X.

[0060] The signal SEL is a switching signal input from the pixel information generating unit 15 to the selectors 125-0, 125-1, 125-2, ... 125-N. When the signal SEL is at a low level (signal value "0"), the output signal of the preceding register 126 is input to each selector 125. When the signal SEL is at a high level (signal value "1"), the light reception count value output from the corresponding pixel 120 is input to each selector 125.

[0061] The pixel information OUT is an output signal output from the pixel information generating unit 15 to the frequency distribution generating unit 16. The pixel information OUT includes a light reception count value of each pixel and a time count value associated therewith. In FIG. 7, "U0(t)" indicates pixel information including a light reception count value from the 0th pixel 120-0 in a period in which the value of the time count value CNT is t. "UN(t)" indicates pixel information including a light reception count value from the Nth pixel 120-N in a period in which the value of the time count value CNT is t. "U0(t+1)" indicates pixel information including a light reception count value from the 0th pixel 120-0 in a period in which the value of the time count value CNT is (t+1). "UN(t+1)" indicates pixel information including a light reception count value from the Nth pixel 120-N in a period in which the value of the time count value CNT is (t+1). The notations of other values ​​of the pixel information OUT are defined similarly.

[0062] Next, the change over time of each signal will be described with reference to Fig. 7. At time T0, the clock signal SR_CLK transitions (rises) from low level to high level. At this time, the value of the time count value CNT counts up from (t-1) to t. The time count value CNT counts up by 1 each time the number of times the clock signal SR_CLK rises reaches a predetermined number. In this embodiment, this predetermined number, i.e., the number of pulses of the clock signal SR_CLK per count of the time count value CNT, is assumed to match the number of pixels 120 (N+1), but is not limited to this.

[0063] When the rising edge of the clock signal SR_CLK is input to each register 126 while the signal SEL is at a high level, each register 126 holds the light reception count value output from the corresponding pixel 120. Therefore, at the timing of time T0, each register 126 holds the light reception count value output from the corresponding pixel 120. At this time, the signal SR_OUT which is the output signal of the Nth register 126-N is the light reception count value (PN(t)) output from the Nth pixel 120-N.

[0064] After time T0, the signal SEL starts to transition from high level to low level. When the rising edge of the clock signal SR_CLK is input to each register 126 while the signal SEL is at low level, each register 126 holds the output signal of the register 126 in the previous stage. Therefore, after time T0, each time the rising edge of the clock signal SR_CLK is input to the register 126, the shift register performs an operation of shifting the held signal by one stage. That is, at the timing when the value of the time count value CNT counts up from (t-1) to t, the shift register completes holding the light-receiving count value, and the shift register is switched to a state in which it can perform an operation of shifting the light-receiving count value.

[0065] At time T1, the clock signal SR_CLK transitions (falls) from high to low. The pixel information generation unit 15 sequentially acquires the value of the signal SR_OUT each time the falling edge of the clock signal SR_CLK is input, and generates and outputs pixel information OUT. At time T1, the pixel information generation unit 15 acquires PN(t) as the signal SR_OUT, and outputs UN(t) as the pixel information OUT.

[0066] After time T1, shifting of the signal held in the shift register and reading of the signal to the pixel information generating unit 15 are sequentially repeated in response to the transition of the clock signal SR_CLK. As an example, at time T2, the clock signal SR_CLK rises, and the signal SR_OUT, which is the output signal of the Nth register 126-N, becomes the light reception count value (P2(t)) output from the second pixel 120-2. Thereafter, at time T3, the clock signal SR_CLK falls, and the pixel information generating unit 15 obtains P2(t) as the signal SR_OUT and outputs U2(t) as the pixel information OUT. As another example, at time T4, the clock signal SR_CLK rises, and the signal SR_OUT, which is the output signal of the Nth register 126-N, becomes the light reception count value (P1(t)) output from the first pixel 120-1. At a subsequent time T5, the clock signal SR_CLK falls, and the pixel information generator 15 acquires P1(t) as the signal SR_OUT, and outputs U1(t) as the pixel information OUT.

[0067] After time T6, the signal SEL starts to transition from low level to high level. After that, when the rising edge of the clock signal SR_CLK is input to each register 126 at time T7, the register 126 holds the light reception count value (PN(t+1), ... P2(t+1), P1(t+1), P0(t+1)) output from the corresponding pixel 120. Also, at time T7, the value of the time count value CNT counts up from t to (t+1) in response to the rising edge of the clock signal SR_CLK. Therefore, the period from time T0 to time T7 is the period during which the time count value CNT is one value (t) (i.e., the period required for the time count value to change by 1), and this period corresponds to one bin period in generating the frequency distribution. Within this period, multiple periods of the clock signal SR_CLK are included, and the clock signal SR_CLK rises multiple times. In other words, the period of the pulse of the clock signal SR_CLK is shorter than the period during which the time count value CNT changes. Therefore, the pixel information generating section 15 can read out the light reception count values ​​PX from the multiple pixels 120 during the period in which the time count value CNT is one value t.

[0068] In the period from time T7 to time T9, the same processing as in the period from time T0 to time T7 is performed, except that the time count value changes from t to (t+1). Also, in the period before time T0 and the period after time T9, the same processing as in the period from time T0 to time T7 is repeated, except that the time count value is different.

[0069] As described above, the period required for the time count value to change by 1 from t to (t+1) is the period from time T0 to time T7. The period during which the pixel information generating unit 15 acquires the light reception count value of each of the multiple pixels 120 and outputs the pixel information OUT is the period from time T1 to time T8. Here, the time during which the time count value changes by 1 is equal to the length of the period during which the pixel information generating unit 15 acquires the light reception count value of each of the multiple pixels 120 and outputs the pixel information OUT of each of the multiple pixels 120. This can reduce the loss of information on the incident light caused by the value of the time count value CNT changing during the readout of the multiple pixels 120. Note that the same effect can be obtained if the length of the period during which the pixel information generating unit 15 acquires the light reception count value of each of the multiple pixels 120 and outputs the pixel information OUT of each of the multiple pixels 120 is equal to or less than the time during which the time count value changes by 1.

[0070] In this embodiment, the pixel information generating unit 15 outputs pixel information OUT for each of the multiple pixels 120 during a period of the same length as the time during which the time count value changes by 1. However, this time count value may be a predetermined value greater than 1, although the above-mentioned effects may vary. In other words, the pixel information generating unit 15 may be configured to obtain the light receiving count value for each of the multiple pixels 120 and output the pixel information OUT for each of the multiple pixels 120 within a period of the length equal to or less than the time during which the time count value changes by the predetermined value.

[0071] As described above, according to this embodiment, a distance measuring device 1 capable of reducing loss of information on incident light is provided.

[0072] 7 shows an example in which the pixel information generating unit 15 obtains the value of the signal SR_OUT in response to the falling edge of the clock signal SR_CLK, and generates and outputs the pixel information OUT, but is not limited to this. For example, the pixel information generating unit 15 may obtain the value of the signal SR_OUT in response to the rising edge of the clock signal SR_CLK, and generate and output the pixel information OUT.

[0073] 5 shows a configuration in which the pixels 120 are arranged in one row and multiple columns, and the pixel information generating unit 15 is arranged corresponding to this one row, but the pixels 120 may be arranged in multiple rows and multiple columns. In this case, the pixel information generating unit 15 may process the output signals of the pixels 120 for each row, or may process the output signals of multiple rows collectively.

[0074] [Second embodiment] In the first embodiment, the pixel information generation unit 15 sequentially outputs pixel information OUT of the multiple pixels 120 in response to the clock signal SR_CLK. In this embodiment, a configuration example will be described in which the pixel information generation unit 15 can output pixel information OUT of the multiple pixels 120 in parallel. Descriptions of elements common to the first embodiment may be omitted or simplified as appropriate.

[0075] Fig. 8 is a diagram showing the configurations of the light receiving unit 12, the control unit 13, the time count unit 14, and the pixel information generation unit 15 according to this embodiment. The configurations of the light receiving unit 12, the control unit 13, and the time count unit 14 are the same as those in Fig. 5. The pixel information generation unit 15 has a generation processing unit 15a and a plurality of registers 151. The number of the plurality of registers 151 is assumed to be N, and Fig. 8 shows registers 151-1, 151-2, ... 125-N with branch numbers.

[0076] The generation processing unit 15a is a circuit that performs the same operation as the pixel information generation unit 15 in the first embodiment. The generation processing unit 15a receives the time count value CNT from the time count unit 14, the signal SR_OUT from the register 126-N, and the clock signal SR_CLK from the control unit 13. The generation processing unit 15a outputs pixel information OUT for each pixel 120 in sequence.

[0077] Each of the registers 151-1, 151-2, ..., 151-N has an input terminal, an output terminal, and a control terminal. Each of the registers 151-1, 151-2, ..., 151-N has a function of holding an input signal and may include a flip-flop circuit. The control unit 13 outputs a clock signal SR_CLK to the control terminal of the register 151 in addition to the register 126 and the pixel information generation unit 15.

[0078] The pixel information OUT output from the generation processing unit 15a is input to the input terminal of the register 151-1. The output terminal of the register 151-1 is connected to the input terminal of the register 151-2. Similarly, the registers 151-1, 151-2, ..., 151-N are connected in series to form a shift register. Each of the registers 151-1, 151-2, ..., 151-N holds a signal input to the input terminal at the timing when the clock signal SR_CLK falls, and continues to output the signal from the output terminal. As a result, an operation is performed in which the signal held in the register 151 of each stage is shifted to the register 151 of the next stage every time the clock signal SR_CLK falls.

[0079] The node of the output terminal of the generation processing unit 15a and the nodes of the output terminals of the registers 151-1, 151-2, ..., 151-N are connected to a plurality of output terminals of the pixel information generation unit 15. The signal output from the node of the output terminal of the generation processing unit 15a is pixel information OUT[0]. The signals output from the nodes of the output terminals of the registers 151-1, 151-2, ..., 151-N are pixel information OUT[1], OUT[2], ..., OUT[N]. The pixel information OUT[0] is the same as the pixel information OUT. The plurality of output terminals of the pixel information generation unit 15 are connected to the frequency distribution generation unit 16. That is, in this embodiment, the pixel information generation unit 15 outputs the pixel information OUT[0], OUT[1], OUT[2], ..., OUT[N] to the frequency distribution generation unit 16 in parallel.

[0080] Fig. 9 is a timing chart showing the operation of the distance measuring device according to this embodiment. Fig. 9 shows the time changes of the time count value CNT, the clock signal SR_CLK, the signal SR_OUT, the light reception count value PX, the signal SEL, and the pixel information OUT[0], OUT[1], OUT[2], ..., OUT[N] shown in Fig. 8 or Fig. 6(a). The time changes of the time count value CNT, the clock signal SR_CLK, the signal SR_OUT, the light reception count value PX, and the signal SEL are the same as those in Fig. 7. The time change of the pixel information OUT[0] is the same as the pixel information OUT in Fig. 7.

[0081] Since the registers 151-1, 151-2, ..., 151-N form a shift register, as shown in Fig. 9, each time the clock signal SR_CLK falls, each register 151 holds the output signal of the previous register 151. Therefore, each time the falling edge of the clock signal SR_CLK is input to the register 151, the shift register performs an operation of shifting the held signal by one stage. For example, when the clock signal SR_CLK falls at time T5, U2(t) that was output from the generation processing unit 15a as the 0th pixel information OUT[0] in the period before time T5 is held in the first register 151-1. As a result, in the period after time T5, the first register 151-1 outputs U2(t) as the first pixel information OUT[1].

[0082] In this way, the signals are shifted in the registers 151-1, 151-2, ..., 151-N. At a subsequent time T7, the pixel information OUT[0], OUT[1], OUT[2], ..., OUT[N] become U0(t), U1(t), U2(t), ..., UN(t), respectively, and the pixel information corresponding to each pixel 120 is parallelized and output. In this way, the shift register formed by the registers 151-1, 151-2, ..., 151-N functions as a serial-parallel conversion circuit that serially converts the pixel information OUT output from the generation processing unit 15a. This allows the pixel information generation unit 15 to output the pixel information OUT[0], OUT[1], OUT[2], ..., OUT[N] in parallel to the frequency distribution generation unit 16.

[0083] In a configuration in which pixel information OUT of each pixel 120 is output sequentially as in the first embodiment, the pixel information OUT is input to the frequency distribution generating unit 16 in the same cycle as the clock signal SR_CLK. In contrast, pixel information OUT[0], OUT[1], OUT[2], ... OUT[N] of each pixel 120 is input in parallel to the frequency distribution generating unit 16 in the same cycle as the count-up cycle of the time count value CNT. Therefore, the processing cycle of the frequency distribution generating unit 16 can be lengthened, and the processing load is reduced.

[0084] According to this embodiment, similarly to the first embodiment, a distance measuring device 1 capable of reducing loss of information of incident light is provided. Moreover, in this embodiment, the processing cycle of the frequency distribution generating unit 16 can be lengthened, and the processing load can be reduced.

[0085] [Third embodiment] 5 of the first embodiment, a configuration in which a plurality of pixels 120 are arranged in one row in the light receiving unit 12 is illustrated as an example, but the plurality of pixels 120 may be arranged to form a plurality of rows and a plurality of columns. In this embodiment, a configuration example in which a plurality of pixels 120 are arranged to form a plurality of rows and a plurality of columns will be described. Descriptions of elements common to the first or second embodiment may be omitted or simplified as appropriate.

[0086] FIG. 10 is a diagram showing the configuration of the light receiving section 12, the control section 13, the time count section 14, and the pixel information generating section 15 according to this embodiment. The light receiving section 12 includes a pixel block 12a and a pixel block 12b. Each of the pixel block 12a and the pixel block 12b includes elements similar to those of the light receiving section 12 of the first embodiment. The light receiving section 12 includes pixels 120 arranged to form a plurality of rows and a plurality of columns. The pixel block 12a includes the pixels 120 in the first row of the plurality of rows. The pixel block 12b includes the pixels 120 in the second row of the plurality of rows. The plurality of selectors 125 and the plurality of registers 126 are arranged to correspond to the plurality of pixels 120, respectively, as in the first embodiment. The control section 13 outputs a clock signal SR_CLK to the register 126 of the pixel block 12a, the register 126 of the pixel block 12b, and the pixel information generating section 15.

[0087] The output terminal of the register 126-N of the pixel block 12a and the output terminal of the register 126-N of the pixel block 12b are both connected to a common pixel information generator 15. That is, the light reception count values ​​from the pixels 120 in the two rows are input to the common pixel information generator 15. Therefore, the time count unit 14 and the pixel information generator 15 are shared by the two rows.

[0088] The pixel information generating unit 15 may process the light reception count values ​​for two rows one by one sequentially or in parallel. For example, when the distance measuring device 1 performs distance measuring using the Flash method, signals may be output simultaneously from multiple rows of registers 126-N. Even in such a case, the pixel information generating unit 15 may process the light reception count values ​​for two rows one by one sequentially or in parallel to avoid missing pixel information. The pixel information generating unit 15 may also add identification information to the pixel information and then output pixel information of only the pixels 120 in one of the rows.

[0089] Furthermore, the pixel information generating unit 15 may process the output signals of two rows by calculating a logical sum. For example, when the distance measuring device 1 performs distance measuring processing one row at a time, such as in the Sequential Flash method, loss of pixel information due to the logical sum calculation method can be avoided.

[0090] According to this embodiment, similarly to the first embodiment, a distance measuring device 1 capable of reducing loss of information of incident light is provided. In addition, in this embodiment, multiple rows of pixels 120 share the time count unit 14 and the pixel information generating unit 15, and the circuit scale can be reduced, so that the distance measuring device 1 can be made compact.

[0091] [Fourth embodiment] In FIG. 5 of the first embodiment, a configuration in which a plurality of pixels 120 are arranged in one row in the light receiving section 12 is illustrated as an example, but the pixels 120 connected to one shift register may be all or a part of the pixels 120 included in one row. In this embodiment, a configuration example in which a part of the pixels 120 in one row are connected to one shift register will be described. In addition, in this embodiment, two time count units 14-1 and 14-2 (first time count unit, second time count unit) and two pixel information generating units 15-1 and 15-2 (first pixel information generating unit, second pixel information generating unit) are arranged for the pixels 120 in one row. Descriptions of elements common to the first to third embodiments may be omitted or simplified as appropriate.

[0092] FIG. 11 is a diagram showing the configuration of the light receiving section 12, the control section 13, the time counting sections 14-1 and 14-2, and the pixel information generating sections 15-1 and 15-2 according to this embodiment. The light receiving section 12 includes a pixel block 12c and a pixel block 12d. Each of the pixel block 12c and the pixel block 12d includes elements similar to those of the light receiving section 12 of the first embodiment. The light receiving section 12 includes pixels 120 arranged to form one or more rows and a plurality of columns. The pixel block 12c includes some of the pixels 120 in one row. The pixel block 12d includes other some of the pixels 120 in the same row as the pixel block 12c. The multiple selectors 125 and the multiple registers 126 are arranged to correspond to the multiple pixels 120, respectively, as in the first embodiment. That is, the pixels 120 in the pixel block 12c and the pixels 120 in the pixel block 12d are processed by different shift registers. The control unit 13 outputs a clock signal SR_CLK to the register 126 of the pixel block 12c, the register 126 of the pixel block 12d, and the pixel information generation units 15-1 and 15-2.

[0093] The output terminal of the register 126-N of the pixel block 12c and the output terminal of the register 126-N of the pixel block 12d are connected to different pixel information generators 15-1 and 15-2, respectively. That is, the light reception count values ​​from the pixels 120 in one row are input to a plurality of pixel information generators 15-1 and 15-2, each of which is different for each pixel block.

[0094] According to this embodiment, as in the first embodiment, a distance measuring device 1 is provided that can reduce loss of information on incident light. In addition, in this embodiment, since the pixels 120 in one row are processed by multiple shift registers, the frequency of the clock signal SR_CLK can be lowered, and signal processing can be facilitated. In addition, in this embodiment, multiple time count units 14-1, 14-2 and multiple pixel information generators 15-1, 15-2 that differ for each pixel block are arranged for the pixels 120 in one row. This allows the number of pixels 120 to which one set of time count unit 14 and pixel information generator 15 is connected to to be reduced, and signal processing can be facilitated.

[0095] [Fifth embodiment] In the fourth embodiment, an example is shown in which two time count units 14-1, 14-2 and two pixel information generators 15-1, 15-2 are arranged for one row of pixels 120. However, the number of time count units 14 and pixel information generators 15 arranged for one row of pixels 120 is not limited to this. For example, one time count unit 14 and one pixel information generator 15 may be arranged for one row of pixels 120. In this embodiment, a configuration example in which one time count unit 14 and one pixel information generator 15 are arranged for one row of pixels 120 will be described. Descriptions of elements common to the first to fourth embodiments may be omitted or simplified as appropriate.

[0096] Fig. 12 is a diagram showing the configurations of the light receiving section 12, the control section 13, the time count section 14, and the pixel information generating section 15 according to this embodiment. The difference from Fig. 11 is that there is one each of the time count section 14 and the pixel information generating section 15, but other points are the same as Fig. 11.

[0097] The output terminal of the register 126-N of the pixel block 12c and the output terminal of the register 126-N of the pixel block 12d are both connected to a common pixel information generator 15. That is, the light reception count value from the pixel 120 of the pixel block 12c and the light reception count value from the pixel 120 of the pixel block 12d are input in parallel to the common pixel information generator 15. Therefore, one set of the time count unit 14 and the pixel information generator 15 is shared by the two pixel blocks 12c and 12d.

[0098] The pixel information generating unit 15 may process the light reception count values ​​of the two pixel blocks 12c and 12d one by one in sequence or in parallel. There are cases where signals are output simultaneously from the registers 126-N of the two pixel blocks 12c and 12d. Even in such a case, the pixel information generating unit 15 may process the light reception count values ​​of the two pixel blocks 12c and 12d one by one in sequence or in parallel to avoid missing pixel information. The pixel information generating unit 15 may also add identification information to the pixel information and then output only the pixel information of the pixel 120 of one of the pixel blocks 12c and 12d.

[0099] According to this embodiment, similar to the first embodiment, a distance measuring device 1 capable of reducing loss of information of incident light is provided. Also, similar to the fourth embodiment, since the pixels 120 in one row are processed by multiple shift registers, the frequency of the clock signal SR_CLK can be lowered, and signal processing can be facilitated. Also, in this embodiment, multiple pixel blocks share the time count unit 14 and the pixel information generating unit 15, and the circuit scale can be reduced compared to the fourth embodiment, so that the distance measuring device 1 can be made more compact.

[0100] [Sixth embodiment] In the third embodiment, a configuration is shown in which multiple rows of pixels 120 share the time count unit 14 and the pixel information generation unit 15. Also, in the fourth embodiment, a configuration is shown in which one row of pixels 120 is processed by multiple shift registers, multiple time count units 14-1 and 14-2, and multiple pixel information generation units 15-1 and 15-2. In this embodiment, the configurations of the third embodiment and the fourth embodiment are combined. Descriptions of elements common to the first to fifth embodiments may be omitted or simplified as appropriate.

[0101] FIG. 13 is a diagram showing the configuration of the light receiving section 12, the control section 13, the time counting sections 14-1 and 14-2, and the pixel information generating sections 15-1 and 15-2 according to this embodiment. The light receiving section 12 includes a pixel block 12e and a pixel block 12f in addition to the pixel block 12c and the pixel block 12d similar to those in the fourth embodiment. Each of the pixel blocks 12c, 12d, 12e, and 12f includes elements similar to those of the light receiving section 12 in the first embodiment. The light receiving section 12 includes pixels 120 arranged to form a plurality of rows and a plurality of columns. The plurality of rows includes a first row and a second row. The pixel block 12c includes some of the pixels 120 in the first row. The pixel block 12d includes the other part of the pixels 120 in the first row. The pixel block 12e includes some of the pixels 120 in the second row. The pixel block 12f includes the other part of the pixels 120 in the second row. Similar to the first embodiment, the selectors 125 and the registers 126 are arranged to correspond to the pixels 120, respectively. That is, the pixels 120 in the pixel blocks 12c, 12d, 12e, and 12f are processed by different shift registers. The control unit 13 outputs a clock signal SR_CLK to the registers 126 and the pixel information generation unit 15 of the pixel blocks 12c, 12d, 12e, and 12f.

[0102] The output terminal of the register 126-N of the pixel block 12c and the output terminal of the register 126-N of the pixel block 12e are both connected to a common pixel information generator 15-1. That is, the light reception count values ​​from the pixels 120 of the two rows are input to the common pixel information generator 15-1. Therefore, the time count unit 14-1 and the pixel information generator 15-1 are shared by the two rows.

[0103] In addition, the output terminal of the register 126-N of the pixel block 12d and the output terminal of the register 126-N of the pixel block 12f are both connected to a common pixel information generator 15-2. The pixel information generator 15-2 to which the pixel blocks 12d and 12f are connected is a separate circuit from the pixel information generator 15-1 to which the pixel blocks 12c and 12e are connected. In other words, the light reception count values ​​from the pixels 120 in one row are input to multiple pixel information generators 15-1 and 15-2, which differ for each pixel block.

[0104] According to this embodiment, as in the first embodiment, a distance measuring device 1 that can reduce information loss of incident light is provided. As in the third embodiment, the pixels 120 in one row are processed by multiple shift registers, so the frequency of the clock signal SR_CLK can be lowered, and signal processing can be facilitated. As in the third embodiment, multiple time count units 14-1, 14-2 and multiple pixel information generators 15-1, 15-2 that differ for each pixel block are arranged for the pixels 120 in one row. This makes it possible to reduce the number of pixels 120 to which one set of time count unit 14 and pixel information generator 15 is connected, and signal processing can be facilitated. As in the fourth embodiment, multiple rows of pixels 120 share the time count unit 14 and pixel information generator 15, and the scale of the circuit can be reduced, and the distance measuring device 1 can be made smaller. Therefore, the effect of lowering the frequency of the clock signal SR_CLK and the miniaturization of the distance measuring device 1 can be achieved at the same time.

[0105] [Seventh embodiment] 14(a) and 14(b) are block diagrams of devices related to the vehicle-mounted distance measuring device in this embodiment. The device 80 has a distance measuring unit 803, which is an example of the distance measuring device in the above-mentioned embodiment, and a signal processing device (processing device) that processes a signal from the distance measuring unit 803. The device 80 has a distance measuring unit 803 that measures the distance to an object, and a collision determination unit 804 that determines whether or not there is a possibility of collision based on the measured distance. Here, the distance measuring unit 803 is an example of a distance information acquisition unit that acquires distance information to the object. That is, the distance information is information related to the distance to the object, etc. The collision determination unit 804 may determine the possibility of collision using the distance information.

[0106] The 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. In addition, the device 80 is connected to a control ECU 820, which is a control device that outputs a control signal to generate a braking force for the vehicle based on the judgment result of the collision judgment unit 804. In addition, the device 80 is also connected to an alarm device 830 that issues an alarm to the driver based on the judgment result of the collision judgment unit 804. For example, when the judgment result of the collision judgment unit 804 indicates that there is a high possibility of a collision, the control ECU 820 performs vehicle control to avoid a collision and reduce damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. 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, etc., and applying vibrations to a seat belt or steering wheel. These devices of the device 80 function as a mobile object control unit that controls the operation of controlling the vehicle as described above.

[0107] In this embodiment, the device 80 measures distances around the vehicle, for example, in front or behind. Fig. 14(b) shows the device when measuring distances in front of the vehicle (distance measurement range 850). A vehicle information acquisition device 810 as a distance measurement control means sends an instruction to the device 80 or distance measurement unit 803 to perform a distance measurement operation. With this configuration, the accuracy of distance measurement can be further improved.

[0108] Although the above describes an example of control to prevent collision with other vehicles, the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from lanes, etc. Furthermore, the device is not limited to vehicles such as automobiles, but can be applied to moving bodies (moving devices) such as ships, aircraft, artificial satellites, industrial robots, and consumer robots. In addition, the present invention can be applied to devices that use object recognition or biometric recognition, such as intelligent transport systems (ITS) and surveillance systems, in addition to moving bodies.

[0109] [Modified embodiment] The present invention is not limited to the above-described embodiments and can be modified in various ways. For example, an example in which a part of the configuration of any of the embodiments is added to another embodiment, or an example in which a part of the configuration of any of the embodiments is replaced with a part of the configuration of another embodiment, is also an embodiment of the present invention.

[0110] In the second embodiment, an example is shown in which a shift register composed of registers 151-1, 151-2, ... 151-N is added to the configuration of the first embodiment, but serial-parallel conversion using a shift register is also applicable to the other embodiments. For example, the configuration of the pixel information generation unit 15 in the third to sixth embodiments may be replaced with the configuration of the pixel information generation unit 15 in the second embodiment.

[0111] In the first to sixth embodiments, a configuration in which a plurality of pixels 120 arranged in one row are connected to one shift register is illustrated, but the arrangement of the plurality of pixels 120 is not limited to this. For example, a configuration in which a plurality of pixels 120 arranged in one column are connected to one shift register may also be used.

[0112] The disclosure of this specification includes the complement of the concepts described in this specification. In other words, if the specification states, for example, that "A is B" (A=B), the specification is deemed to disclose or suggest that "A is not B" even if the statement that "A is not B" (A≠B) is omitted. This is because when it states that "A is B," it is assumed that the case that "A is not B" is taken into consideration.

[0113] The disclosure of this specification includes the following configurations. (Configuration 1) a time count unit that outputs a time count value indicating an elapsed time from when the time count started; a light receiving section having a plurality of pixels and outputting a light receiving count value of light incident on each of the plurality of pixels; a pixel information generating unit that outputs pixel information in which the light reception count value and the time count value are associated with each other for each pixel; having The pixel information generating unit acquires the light reception count value of each of the plurality of pixels within a period of time that is equal to or shorter than the time during which the time count value changes by a predetermined value, and outputs the pixel information of each of the plurality of pixels. A distance measuring device comprising: (Configuration 2) The predetermined value is 1. 2. The distance measuring device according to configuration 1, (Configuration 3) a control unit that controls the timing of emitting light from a light emitting unit that emits light and the timing of starting the time count in synchronization with each other; 3. The distance measuring device according to configuration 1 or 2, further comprising: (Configuration 4) The light receiving unit further includes a shift register that holds the light receiving count value corresponding to each of the plurality of pixels. 4. The distance measuring device according to any one of configurations 1 to 3. (Configuration 5) The shift register includes a sequential circuit corresponding to each of the plurality of pixels. 5. The distance measuring device according to configuration 4. (Configuration 6) The shift register sequentially outputs the light reception count values ​​corresponding to the plurality of pixels in response to pulses of a clock signal. 6. A distance measuring device according to configuration 4 or 5. (Configuration 7) The period of the pulse of the clock signal is shorter than the period during which the time count value changes. 7. The distance measuring device according to configuration 6. (Configuration 8) The number of pulses of the clock signal input during a period in which the time count value is a constant value is equal to the number of pixels corresponding to the pixel information. 8. The distance measuring device according to configuration 6 or 7. (Configuration 9) The light-receiving count value is output from each of the plurality of pixels to the shift register, and a selector is configured to switch between a first state and a second state in which the light-receiving count value held in the shift register is shifted. 9. The distance measuring device according to any one of configurations 4 to 8. (Configuration 10) The selector switches from the first state to the second state at a timing when the time count value changes. 10. The distance measuring device according to configuration 9. (Configuration 11) The pixel information generating unit outputs the pixel information of each of the plurality of pixels in parallel. 11. The distance measuring device according to any one of configurations 1 to 10. (Configuration 12) The pixel information generating unit includes a generating processing unit that sequentially outputs the pixel information for each pixel, and a serial-to-parallel conversion circuit that serially converts the pixel information into parallel information. 12. A distance measuring device according to claim 11, (Configuration 13) The serial-to-parallel conversion circuit includes a shift register. 13. A distance measuring device according to claim 12. (Configuration 14) The pixels are arranged in a plurality of rows and a plurality of columns, the plurality of rows includes a first row and a second row; The pixel information generating unit receives the light reception count value of the pixels in the first row and the light reception count value of the pixels in the second row. 14. The distance measuring device according to any one of configurations 1 to 13. (Configuration 15) The pixels are arranged in a plurality of rows and a plurality of columns, The pixel information generating unit receives the light reception count values ​​of some pixels among the pixels included in one row and the light reception count values ​​of other pixels among the pixels included in the one row in parallel. 14. The distance measuring device according to any one of configurations 1 to 13. (Configuration 16) A plurality of the pixel information generating units are provided, The pixels are arranged in a plurality of rows and a plurality of columns, a first pixel information generating unit among the plurality of pixel information generating units receives the light reception count values ​​of some of the pixels included in one row; The light reception count values ​​of the other part of the pixels included in the one row are input to a second pixel information generating unit among the plurality of pixel information generating units. 14. The distance measuring device according to any one of configurations 1 to 13. (Configuration 17) A plurality of the pixel information generating units are provided, The pixels are arranged in a plurality of rows and a plurality of columns, the plurality of rows includes a first row and a second row; a first pixel information generating unit among the plurality of pixel information generating units receives the light reception count values ​​of some of the pixels in the first row and the light reception count values ​​of some of the pixels in the second row in parallel; The light reception count values ​​of another part of the pixels in the first row and the light reception count values ​​of another part of the pixels in the second row are input in parallel to a second pixel information generating unit among the plurality of pixel information generating units. 14. The distance measuring device according to any one of configurations 1 to 13. (Configuration 18) A plurality of the time count units are provided, a first time count unit among the plurality of time count units outputs the time count value to the first pixel information generation unit; A second time count unit among the plurality of time count units outputs the time count value to the second pixel information generating unit. 18. A distance measuring device according to configuration 16 or 17. (Configuration 19) The light receiving device further includes a frequency distribution generating unit that generates a frequency distribution indicating a frequency of the light receiving count value at each time count value based on the pixel information. 19. A distance measuring device according to any one of configurations 1 to 18. (Configuration 20) A mobile object, A distance measuring device according to any one of configurations 1 to 19, a distance information acquisition unit that acquires distance information to an object from the pixel information; a moving object control unit that controls the moving object based on the distance information; A moving object comprising:

[0114] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) for implementing one or more of the functions.

[0115] It should be noted that the above-mentioned embodiments are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these embodiments. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0116] 1 Ranging device 12 Light receiving part 14 Time counter section 15 Pixel information generation unit 120 pixels

Claims

1. a time count unit that outputs a time count value indicating an elapsed time from when the time count started; a light receiving section having a plurality of pixels and outputting a light receiving count value of light incident on each of the plurality of pixels; a pixel information generating unit that outputs pixel information in which the light reception count value and the time count value are associated with each other for each pixel; having The pixel information generating unit acquires the light reception count value of each of the plurality of pixels within a period of time that is equal to or shorter than the time during which the time count value changes by a predetermined value, and outputs the pixel information of each of the plurality of pixels. A distance measuring device comprising:

2. The predetermined value is 1.

2. A distance measuring device according to claim 1.

3. a control unit that controls the timing of emitting light from a light emitting unit that emits light and the timing of starting the time count in synchronization with each other; 2. The distance measuring device according to claim 1, further comprising:

4. The light receiving unit further includes a shift register that holds the light receiving count value corresponding to each of the plurality of pixels.

2. A distance measuring device according to claim 1.

5. The shift register includes a sequential circuit corresponding to each of the plurality of pixels.

5. A distance measuring device according to claim 4.

6. The shift register sequentially outputs the light reception count values ​​corresponding to the plurality of pixels in response to pulses of a clock signal.

5. A distance measuring device according to claim 4.

7. The period of the pulse of the clock signal is shorter than the period during which the time count value changes.

7. A distance measuring device according to claim 6.

8. The number of pulses of the clock signal input during a period in which the time count value is a constant value is equal to the number of pixels corresponding to the pixel information.

7. A distance measuring device according to claim 6.

9. The light-receiving count value stored in the shift register is shifted from the first state to the second state.

5. A distance measuring device according to claim 4.

10. The selector switches from the first state to the second state at a timing when the time count value changes.

10. The distance measuring device according to claim 9.

11. The pixel information generating unit outputs the pixel information of each of the plurality of pixels in parallel.

2. A distance measuring device according to claim 1.

12. The pixel information generating unit includes a generating processing unit that sequentially outputs the pixel information for each pixel, and a serial-to-parallel conversion circuit that serially converts the pixel information into parallel information.

12. A distance measuring device according to claim 11.

13. The serial-to-parallel conversion circuit includes a shift register.

13. A distance measuring device according to claim 12.

14. The pixels are arranged in a plurality of rows and a plurality of columns, the plurality of rows includes a first row and a second row; The pixel information generating unit receives the light reception count value of the pixels in the first row and the light reception count value of the pixels in the second row.

2. A distance measuring device according to claim 1.

15. The pixels are arranged in a plurality of rows and a plurality of columns, The pixel information generating unit receives the light reception count values ​​of some of the pixels included in one row and the light reception count values ​​of other of the pixels included in the one row in parallel.

2. A distance measuring device according to claim 1.

16. A plurality of the pixel information generating units are provided, The pixels are arranged in a plurality of rows and a plurality of columns, a first pixel information generating unit among the plurality of pixel information generating units receives the light reception count values ​​of some of the pixels included in one row; The light reception count values ​​of the other part of the pixels included in the one row are input to a second pixel information generating unit among the plurality of pixel information generating units.

2. A distance measuring device according to claim 1.

17. A plurality of the pixel information generating units are provided, The pixels are arranged in a plurality of rows and a plurality of columns, the plurality of rows includes a first row and a second row; a first pixel information generating unit among the plurality of pixel information generating units receives the light reception count values ​​of some of the pixels in the first row and the light reception count values ​​of some of the pixels in the second row in parallel; The light reception count values ​​of another part of the pixels in the first row and the light reception count values ​​of another part of the pixels in the second row are input in parallel to a second pixel information generating unit among the plurality of pixel information generating units.

2. A distance measuring device according to claim 1.

18. A plurality of the time count units are provided, a first time count unit among the plurality of time count units outputs the time count value to the first pixel information generation unit; A second time count unit among the plurality of time count units outputs the time count value to the second pixel information generating unit.

17. A distance measuring device according to claim 16.

19. The light receiving device further includes a frequency distribution generating unit that generates a frequency distribution indicating a frequency of the light receiving count value at each time count value based on the pixel information.

2. A distance measuring device according to claim 1.

20. A mobile object, A distance measuring device according to any one of claims 1 to 19, a distance information acquisition unit that acquires distance information to an object from the pixel information; a moving object control unit that controls the moving object based on the distance information; A moving object comprising:

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