Light detection device and distance measuring system

Abstract

[Problem] To improve distance measurement accuracy using a small amount of light emission and a small amount of light reception regardless of the distance from an object. [Solution] The light detection device comprises: a light receiving unit for receiving, within a first time range, a first reflected light pulse signal generated by reflecting a first light pulse signal emitted at a first time interval by an object, within a second time range different from the first time interval, receiving a second reflected light pulse signal generated by reflecting a second light pulse signal emitted at a second time interval different from the first time interval by the object; and a histogram generator for generating a first histogram in which reception frequencies of the first reflected light pulse signals received in the first time range are classified for each predetermined fixed unit period, and for generating a second histogram in which reception frequencies of the second reflected light pulse signals received in the second time range are classified for each predetermined fixed unit period. Reception frequencies of the second reflected light pulse signals received in the second time range are classified for each unit period.

Description

Technical Field

[0001] The present disclosure relates to a light detection device and a distance measurement system. Background Art

[0002] A distance measurement method called a time-of-flight (ToF) scheme is known, which emits light from an object and measures the distance to the object based on the light reflected from the object. ToF methods include: a direct ToF (dToF) method that measures the distance of an object based on the time difference between the light emission timing and the light reception timing; and an indirect ToF (iToF) method that measures the distance of an object based on the shift between the light emission phase and the light reception phase. In any scheme, in order to improve the distance measurement accuracy, it is necessary to perform multiple distance measurements by repeatedly emitting light and repeatedly receiving reflected light from the object.

[0003] However, in the case where the distance to the object is long, the round trip interval of the light from when the light is emitted to when the reflected light is received may be longer than the light emission interval of the light. In this case, the distance measuring unit may erroneously perform the distance measurement calculation for the light emission timing corresponding to the received reflected light, and the distance measurement accuracy is reduced. In order to solve this problem, a technology is proposed that emits light beams with different light emission periods and superimposes their reflected light beams to accurately perform distance measurement calculations (for example, non-patent document 1).

[0004] Reference List

[0005] Non-patent literature

[0006] Non-patent literature 1: Phase Unwrapping in Indirect Time of Flight | Chronoptics Time-of-Flight

[0007] (https: / / medium.com / chronoptics-time-of-flight / phase-wrapping-and-its-soluti on-in-time-of-flight-depth-sensing-493aa8b21c42) Summary of the invention

[0008] Problems to be solved by the present invention

[0009] The content disclosed in non-patent document 1 is only a conceptual description of the iToF scheme, and no specific system configuration is disclosed. In particular, non-patent document 1 does not disclose a specific system configuration in the dToF scheme. The dToF scheme is often used in light detection and ranging (LiDAR) used in automatic driving technology, and therefore, a technology for improving distance accuracy in a dToF scheme with a small number of light emission and light reception times is needed.

[0010] Therefore, the present disclosure provides a light detection device and a distance measurement system capable of improving distance measurement accuracy with a small number of times of light emission and light reception regardless of the distance of an object.

[0011] Solution to the problem

[0012] In order to solve the problem, the light detection device of the present invention includes:

[0013] a light receiving unit that receives a first reflected light pulse signal within a first time range and a second reflected light pulse signal within a second time range different from the first time range, in which the first reflected light pulse signal is reflected by the object at a first time interval and in which the second reflected light pulse signal is reflected by the object at a second time interval different from the first time interval; and

[0014] A histogram generator generates a first histogram and a second histogram. In the first histogram, the light receiving frequency of the first reflected light pulse signal received within the first time range is classified for each predetermined fixed unit period. In the second histogram, the light receiving frequency of the second reflected light pulse signal received within the second time range is classified for each unit period.

[0015] Alternatively, the light detection device further includes a replica histogram generating unit that generates a first replica histogram obtained by replicating the first histogram by a first number corresponding to the first time interval, and generates a second replica histogram obtained by replicating the second histogram by a second number corresponding to the second time interval.

[0016] The light receiving unit may receive two or more reflected light pulse signals within two or more different time ranges, wherein among the two or more reflected light pulse signals, two or more light pulse signals emitted at two or more time intervals including a first time interval and a second time interval different from each other are reflected by the object,

[0017] The histogram generator may generate two or more histograms obtained by classifying the light reception frequencies of two or more reflected light pulse signals received within two or more time ranges for each unit period,

[0018] The replica histogram generator may generate two or more replica histograms, the two or more replica histograms being obtained by replicating each of the two or more histograms by a number corresponding to the corresponding time interval,

[0019] The two or more histograms generated by the histogram generator may include a first histogram and a second histogram, and

[0020] The two or more replicated histograms generated by the replicated histogram generator may include a first replicated histogram and a second replicated histogram.

[0021] The light receiving section may include a plurality of pixels arranged in two or more in each of the first direction and the second direction, and

[0022] Each of the plurality of pixels may receive more than two reflected light pulse signals within more than two time ranges.

[0023] The light detection device may further include: a packet generator, which generates ranging data including more than two histograms in units of frames,

[0024] The ranging data may include a start portion, a plurality of groups and an end portion.

[0025] The beginning portion may include an identifier indicating a header of the frame and the number of two or more time intervals,

[0026] The packet may include a header, histogram data, and a footer, the header including a corresponding histogram interval count and a number of pixels among two or more histograms, the histogram data constituting the corresponding histogram, the footer including end information of the corresponding histogram, and

[0027] The end portion may include an identifier indicating the end of the frame.

[0028] The light detection device may further include: a packet generator, which generates ranging data including more than two histograms in units of frames,

[0029] The ranging data may include a start portion, a plurality of groups and an end portion.

[0030] The start portion may include an identifier indicating a header of the frame, a number of a plurality of pixels, and a number of more than two time intervals,

[0031] The packet may include a header, histogram data, and a trailer, the header including information indicating a pixel position, the histogram data constituting a corresponding histogram among the two or more histograms, the trailer including end information of the corresponding histogram, and

[0032] The end portion may include an identifier indicating the end of the frame.

[0033] Alternatively, the light detection device further includes a ranging unit that measures the distance of an object based on a light reception time when light reception times corresponding to peak positions of two or more replica histograms including a first replica histogram and a second replica histogram match each other, or a light reception time corresponding to a maximum peak position of a reconstructed histogram synthesized by aligning interval counts of two or more replica histograms.

[0034] The distance measuring unit may add two or more replica histograms for each interval to generate a reconstructed histogram.

[0035] Each of the two or more replicate histograms may have the same bin counts, and

[0036] The distance measuring section may search for a common interval in which each of the two or more replica histograms has a peak value of the light reception frequency, and generate the reconstructed histogram based on a minimum peak value in the searched intervals.

[0037] In addition, the light detection device may further include: a plurality of time-to-digital converters and a plurality of histogram generators, which are arranged for each pixel group including two or more pixels arranged in the first direction.

[0038] Each of the plurality of time-to-digital converters may sequentially generate a digital signal according to the reception time of two or more reflected light pulse signals received by each pixel in the corresponding first pixel group, and

[0039] Each of the plurality of histogram generators may generate two or more histograms based on digital signals sequentially generated by the corresponding time-to-digital converter.

[0040] A plurality of second pixel groups each including two or more pixels arranged in the second direction may be arranged in the first direction, and

[0041] The plurality of second pixel groups may be sequentially selected, and each pixel in the selected second pixel group may input light receiving signals corresponding to more than two reflected light pulse signals to the plurality of time-to-digital converters in parallel.

[0042] Each pixel in the selected second pixel group may sequentially output more than two light receiving signals according to more than two reflected light pulse signals within one frame period, and the light receiving signal outputs of corresponding pixels in the second pixel group may be input to a plurality of time-to-digital converters in parallel.

[0043] The light detection device may further include a plurality of time-to-digital converters and a plurality of histogram generators arranged for each pixel,

[0044] wherein each of the plurality of time-to-digital converters can generate a digital signal corresponding to a reception time of two or more reflected light pulse signals received by a corresponding pixel, and

[0045] Each of the plurality of histogram generators may generate two or more histograms based on the digital signal generated by the corresponding time-to-digital converter.

[0046] Each of the plurality of pixels may sequentially output two or more light reception signals according to two or more reflected light pulse signals within one frame period, and the light reception signal outputs of the corresponding pixels may be input to the plurality of time-to-digital converters in parallel.

[0047] The time-to-digital converter outputs a Gray code corresponding to the time of light reception, and

[0048] The histogram generator may include a conversion table for converting the Gray code into light reception time data.

[0049] The light detection device may further include a storage unit that stores two or more replica histograms having bin counts corresponding to the least common multiple of the two or more time intervals.

[0050] The photodetection device may further include a storage unit having a storage capacity corresponding to a bin count of the histogram, wherein the bin count corresponds to a maximum time interval among the two or more time intervals.

[0051] The light detection device may further comprise:

[0052] an interval expansion unit that stores the histogram corresponding to the maximum time interval as a unit in the storage unit, expands the histograms corresponding to two or more time intervals excluding the maximum time interval by one unit, and stores the histograms in the storage unit;

[0053] a peak detection section that, in a storage area of ​​the storage section including two or more histograms corresponding to two or more time intervals in each cell, repeatedly detects a position where light reception times of peaks of the two or more histograms match each other for each of a plurality of one cells;

[0054] A maximum peak detection unit detects a maximum value of peak values ​​from among the plurality of units;

[0055] a shifting unit that shifts the maximum value of the peak value to the center of the corresponding storage area; and

[0056] The centroid calculation unit performs centroid calculation in the storage area shifted by the shift unit.

[0057] The histogram generator can generate more than two histograms based on more than two reflected light pulse signals repeatedly obtained when the light pulse signal is repeatedly caused to emit light at each of more than two time intervals, and flatten the number of frequencies except for the peaks of the more than two histograms by periodically shifting the start time when the more than two histograms are generated.

[0058] The optical detection device may further include an interference detection unit that detects whether there is interference caused by an unknown optical pulse signal;

[0059] When the interference detecting unit detects that there is no interference, the distance measuring unit may measure the distance to the object based on the reconstructed histogram.

[0060] The optical detection device may further include: a synchronization determination unit, which determines whether it is possible to synchronize with the period switching of the unknown optical pulse signal when interference is detected by the interference detection unit.

[0061] When the synchronization determination unit determines that synchronization is possible, the histogram generator may generate two or more histograms in synchronization with the unknown optical pulse signal.

[0062] The optical detection device may further include a period detection unit, the period detection unit detecting a switching sequence of the period of the unknown optical pulse signal.

[0063] Here, the histogram generator may generate two or more histograms in a switching order in which the switching order of the cycles detected by the cycle detection unit is time-shifted or in a switching order different from the switching order of the cycles detected by the cycle detection unit.

[0064] The optical detection device may further include a light emission timing control section that controls light emission timing of the optical pulse signal including the first optical pulse signal and the second optical pulse signal so as to reduce interference with the unknown optical pulse signal when the synchronization determination section determines that synchronization is impossible.

[0065] The light emission timing control section may randomize a light emission period used to generate the two or more light pulse signals in each of the plurality of histograms included in each of the two or more replica histograms.

[0066] The light emission timing control section may randomize the light emission periods of the two or more light pulse signals so that the total number of light pulse signals used to generate the plurality of histograms is equal for each of the two or more replica histograms.

[0067] In addition, according to the present disclosure, a distance measurement system is provided, comprising: a light emitting device; and a light detecting device, wherein

[0068] The light emitting device comprises:

[0069] A first light emitting unit emits a plurality of first light pulse signals at first time intervals; and

[0070] The second light emitting unit emits a plurality of second light pulse signals at a second time interval, and

[0071] The optical detection device includes a light emission timing control unit, which controls the first light emission unit and the second light emission unit so that after the first light emission unit emits a number of first light pulse signals corresponding to a first time range at a first time interval, the first light emission unit emits a number of second light pulse signals corresponding to a second time range at a second time interval.

[0072] The light emitting device may emit each of the two or more light pulse signals at two or more time intervals by a number corresponding to the corresponding time range, and

[0073] The light emission timing control section may perform control to sequentially emit two or more light pulse signals.

[0074] The optical detection device may include: an interference detection unit, detecting an unknown optical pulse signal; and

[0075] The light emission timing control unit may cause the light emitting device to emit light in a sequence different from the sequence of two or more time intervals for causing the unknown light pulse signal detected by the interference detection unit to emit light, or repeatedly at time intervals different from the two or more time intervals.

[0076] The histogram generator may generate two or more histograms based on the unknown optical pulse signal when the light emitting device is not emitting light, and

[0077] The interference detection section may detect the presence or absence of interference due to the unknown optical pulse signal based on two or more histograms.

[0078] In addition, according to the present disclosure, a ranging system is provided, comprising:

[0079] A light emitting device comprising:

[0080] a first light emitting unit that emits a plurality of first light pulse signals at first time intervals, and

[0081] A second light emitting unit emits a plurality of second light pulse signals at a second time interval;

[0082] a light receiving unit that receives a first reflected light pulse signal within a first time range in which the first light pulse signal is reflected by an object and receives a second reflected light pulse signal within a second time range different from the first time range in which a second light pulse signal emitted at a second time interval different from the first time interval is reflected by the object; and

[0083] A packet generator generates distance measurement data having two or more histograms, wherein the two or more histograms include a first histogram generated based on a first reflected light pulse signal and a second histogram generated based on a second reflected light pulse signal in units of frames, wherein:

[0084] The ranging data includes a start part, a plurality of groups and an end part.

[0085] The start portion includes a header indicating a frame and an identifier of the number of two or more time intervals including a first time interval and a second time interval,

[0086] The packet includes a header, histogram data, and a trailer, the header including the interval counts of the corresponding histograms among the two or more histograms, the histogram data forming the corresponding histogram, the trailer including the end information of the corresponding histogram, and

[0087] The end portion includes an identifier indicating the end of the frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 is a block diagram showing a schematic configuration of a distance measuring system according to a first embodiment of the present disclosure.

[0089] Figure 2A is a diagram for explaining a basic embodiment of a ranging operation of a dToF scheme.

[0090] Figure 2B It is a simplified diagram for explaining the repeated ranging operation.

[0091] Figure 2C is a diagram showing a distance measurement operation in a case where the light round trip interval is longer than the light emission interval.

[0092] Figure 3 1 is a diagram showing an embodiment in which 16-Bin ranging, 14-Bin ranging, and 12-Bin ranging are sequentially performed by changing each light emission interval of a light emitting section.

[0093] Figure 4A is a schematic diagram showing an embodiment of performing 16-bin ranging on an object.

[0094] Figure 4B is a schematic diagram showing an embodiment of performing 14-bin ranging on an object.

[0095] Figure 4C is a schematic diagram showing an embodiment of performing 12-bin ranging on an object.

[0096] Figure 4D is a schematic diagram showing the replicated histogram and peak values.

[0097] Figure 5A It is a flow chart of the ranging process of the ranging system.

[0098] Figure 5B It is a flow chart of ranging calculation.

[0099] Figure 61 is a diagram showing a case where 10Bin ranging, 12Bin ranging, 14Bin ranging, and 16Bin ranging are performed by the ranging system of the present invention.

[0100] Figure 7 It is a diagram showing a detailed first configuration example of a pixel array unit in a photodetection device.

[0101] Figure 8 1 is a timing chart of data transfer from the pixel array section to the SRAM and the distance measurement section in the first configuration embodiment.

[0102] Fig. 9 1 is a diagram showing a detailed second configuration example of a pixel array section in the light detection device.

[0103] Fig.10 is a timing chart of data transfer from the pixel array section to the SRAM and the distance measurement section in the second configuration example.

[0104] Fig.11 It is a flowchart explaining the process of the distance measuring unit.

[0105] Fig.12 : is a diagram showing a distance measuring section and a peripheral section according to a second embodiment.

[0106] Fig.13A is a diagram illustrating an embodiment of dividing a reconstructed histogram into unit histograms.

[0107] Fig. 13B This is a flowchart of the process of the distance measuring unit in the second embodiment.

[0108] Fig. 13C It is a flowchart of the process of the maximum peak detection unit, the shift unit, and the centroid calculation unit.

[0109] Fig.14A is a diagram showing a first configuration example of a distance measuring system according to the third embodiment.

[0110] Fig. 14B : is a diagram showing a second configuration example of the distance measuring system according to the third embodiment.

[0111] Fig.15A 1 is a diagram showing a first embodiment of distance measurement data generated by a packet generation unit.

[0112] Fig. 15B : is a diagram showing the transmission order of the ranging data of the first embodiment.

[0113] Fig. 15C 1 is a diagram showing a transmission order in the case where packets of ranging data have a fixed length in the first embodiment.

[0114] Fig.16A 2 is a diagram showing a second embodiment of distance measurement data generated by a packet generation unit.

[0115] Fig. 16B : is a diagram showing the transmission order of distance measurement data according to the second embodiment.

[0116] Fig.17A is a diagram showing an embodiment in which interfering radio waves are synchronized with a processing cycle such as exposure rotation.

[0117] Fig. 17B This is a diagram showing an embodiment in which the start code of the time-to-digital converter is changed in each processing cycle.

[0118] Fig.18A is a diagram showing an example in which the same number of exposures is performed without performing linear correction in each ranging.

[0119] Fig.18B An embodiment is shown in which the linear correction is performed for the same number of cycles in each ranging.

[0120] Fig.18C An embodiment is shown in which linear correction is performed and the number of exposures is added in each range.

[0121] Fig.19 1 is a diagram showing an example of a ranging cycle of 16-bin ranging in the fourth embodiment.

[0122] Fig. 20A : is a schematic diagram showing an embodiment when the first peak value and the second peak value are obtained in each ranging.

[0123] Fig. 20B It is used to illustrate Fig. 20A A diagram showing the reason why the interval affected by the first peak value appears.

[0124] Fig. 20C 2 is a diagram for explaining a processing operation of the distance measuring device according to the fifth embodiment.

[0125] Fig.20D It is shown in Fig. 20B The illustrated embodiment is a diagram of an embodiment in which a reconstructed histogram is newly generated after deleting the component of the first peak value from the copied histogram.

[0126] Fig.21 This is a flowchart illustrating the process of the distance measuring unit in the fifth embodiment.

[0127] Fig. 22 is a block diagram showing a time-to-digital converter and a histogram generator in the sixth embodiment.

[0128] Fig.23is a diagram showing Gray code in 16-bin ranging.

[0129] Fig.24A is a diagram showing Gray code in 14-bin ranging.

[0130] Fig. 24B is a diagram showing Gray code in 12-bin ranging.

[0131] Fig.24C is a diagram showing a Gray code in a 10Bin range.

[0132] Fig.25A 2 is a diagram for explaining generation of a reconstructed histogram according to the seventh embodiment.

[0133] Fig.25B is a diagram showing the relationship between a replication histogram and a count order histogram.

[0134] Fig.26 is a block diagram showing a configuration of a distance measuring section according to a seventh embodiment.

[0135] Fig. 27 : is a diagram for explaining a method of suppressing the influence of disturbance light of the distance measuring system according to the eighth embodiment.

[0136] Fig.28 is a block diagram showing an interference suppression unit according to the eighth embodiment.

[0137] Fig.29 is a flowchart for realizing the disturbance light suppression method according to the eighth embodiment.

[0138] Fig. 30A is a simplified diagram used to explain the listening modes in detail.

[0139] Fig. 30B is a diagram for explaining a histogram generated in the listening mode.

[0140] Fig. 30C is a diagram illustrating synchronous pull-in.

[0141] Fig.31A is a diagram showing a successful embodiment of other device MOD sequential detection mode.

[0142] Fig.31B 2 is a diagram showing an example of a failure of another device MOD sequential detection mode.

[0143] Fig.32 2 is a diagram showing that other devices synchronize MODs to sequentially change ranging modes.

[0144] Fig.33 is a diagram showing an interference rejection ranging mode.

[0145] Fig.34 It is a block diagram showing an embodiment of a schematic structure of a vehicle control system.

[0146] Fig.35 It is a diagram for assisting in explaining an embodiment of the arrangement positions of the vehicle exterior information detection unit and the imaging portion. DETAILED DESCRIPTION

[0147] Hereinafter, embodiments of the optical detection device and the ranging system will be described with reference to the accompanying drawings. Hereinafter, the main components of the optical detection device and the ranging system will be mainly described, but the optical detection device and the ranging system may also have components or functions not shown. The following description does not exclude components and functions not shown or described.

[0148] (First Embodiment)

[0149] Figure 1 1 is a block diagram showing a schematic configuration of a distance measurement system 1 according to a first embodiment of the present disclosure. The distance measurement system 1 measures the distance to an object OBJ by a dToF scheme and can be installed on, for example, a vehicle-mounted LiDAR. The distance measurement system 1 includes an overall control unit 2, a light emitting device 3, a light detecting device 4, and an application processor (hereinafter referred to as AP) 5.

[0150] The light detecting device 4 and the light emitting device 3 can be formed by a semiconductor chip. In addition, a stacked chip in which a chip having a built-in light detecting device 4 and a chip having a built-in light emitting device 3 are stacked can also be formed. In addition, a chip for the AP 5 can be laminated on the laminated chip. Alternatively, a chip for the light detecting device 4 and a chip for the AP 5 can also be stacked. As described above, at least a part of the components of the ranging system 1 can be configured by one or more semiconductor chips.

[0151] The overall control unit 2 controls the light emitting device 3 and the light detecting device 4. In addition, the overall control unit 2 and the light detecting device 4 or the light emitting device 3 may be integrated.

[0152] For example, the light emitting device 3 intermittently emits a light pulse signal L1 in the frequency band of near infrared light. The light emitting device 3 includes a plurality of light emitting units with different light emission intervals. The light emitting device 3 causes each of the two or more light pulse signals L1 to emit a quantity of light corresponding to the corresponding time range at two or more time intervals. Figure 1 An embodiment is shown in which the light emitting device 3 includes a first light emitting section 11 and a second light emitting section 12, but three or more light emitting sections may be provided. The first light emitting section 11 emits a plurality of first light pulse signals at a first time interval. The second light emitting section 12 emits a plurality of second light pulse signals at a second time interval.

[0153] The light detection device 4 receives a reflected light pulse signal L2 obtained by irradiating the object OBJ with the light pulse signal L1 from the light emitting device 3 and reflecting the light pulse signal L1, and calculates the distance to the object OBJ. The light detection device 4 includes a clock generating section 21, a control section 22, a light emission timing control section 23, a driving circuit 24, a light receiving section 25, a distance measurement control section 26, a distance measurement processing section 27, and an interface (I / F) section 28.

[0154] The clock generation section 21 supplies the control section 22 with a clock signal Vclk for synchronizing the light emitting device 3 and the light detecting device 4 based on the reference clock signal.

[0155] The control section 22 performs control to synchronize the light emission timing control section 23 and the distance measurement control section 26 according to the clock signal Vclk supplied from the clock generation section 21 and an instruction from the overall control section 2 .

[0156] Under the control of the control unit 22, the light emission timing control unit 23 sends a light emission instruction to a plurality of light emission units in the light emission device 3, and performs control so that the light pulse signal L1 emits light sequentially. Figure 1 In the embodiment, the light-emitting timing control unit 23 controls the first light-emitting unit 11 and the second light-emitting unit 12, so that after the first light-emitting unit 11 emits a number of first light pulse signals corresponding to the first time range at a first time interval, the second light-emitting unit 12 emits a number of second light pulse signals corresponding to the second time range at a second time interval.

[0157] The light-emission timing control unit 23 transmits a light-emission instruction to the light-emission device 3 and controls the driving circuit 24 .

[0158] The drive circuit 24 includes a shift register, an address decoder, a pilot, a row selection circuit, a column selection circuit, etc. (not shown) and drives each pixel 30 arranged in the light receiving section 25 in synchronization with the timing when the light emission timing control section 23 sends a light emission instruction.

[0159] The light receiving section 25 receives a reflected light pulse signal L2 obtained by irradiating the object OBJ with the light pulse signal L1 from the light emitting device 3 and reflecting the light pulse signal L1. More specifically, the light receiving section 25 includes a plurality of pixels 30 arranged in a two-dimensional direction, and receives a reflected light pulse signal L2 of each pixel 30.

[0160] For example, in Figure 1In the embodiment, the pixel 30 in the light receiving unit 25 receives a first reflected light pulse signal in a first time range, which is obtained by reflecting the first light pulse signal emitted by the first light emitting unit 11 at a first time interval by the object OBJ, and receives a second reflected light pulse signal in a second time range different from the first time range, which is obtained by reflecting the second light pulse signal emitted by the second light emitting unit 12 at a second time interval different from the first time interval by the object OBJ. As described above, each of the plurality of pixels 30 receives two or more reflected light pulse signals L2 in two or more time ranges.

[0161] The plurality of pixels 30 in the light receiving section 25 supplies a light reception signal indicating a result of light reception to the distance measurement processing section 27 .

[0162] The distance measurement control section 26 controls the distance measurement processing section 27 in synchronization with the light emission timing control section 23 under the control of the control section 22 .

[0163] The distance measurement processing section 27 performs distance measurement calculation by the dToF scheme based on the light reception signals supplied from the plurality of pixels 30. The distance measurement processing section 27 includes a time-to-digital converter (TDC) 41, a histogram generator 42, an SRAM 43, and a distance measurement section 44.

[0164] The time digital converter 41 counts the time difference between the light emission timing of the light emitting device 3 and the light reception timing of the reflected light pulse signal L2 of the light receiving section 25 in synchronization with the light emission timing control section 23 through the distance measurement control section 26. The time digital converter 41 supplies a digital signal corresponding to the count value corresponding to the time difference to the histogram generator 42. In this way, the time digital converter 41 generates a digital signal corresponding to the reception time of the reflected light pulse signal L2, and supplies the digital signal to the histogram generator 42.

[0165] The histogram generator 42 generates a histogram that classifies the light reception frequency at each predetermined fixed unit time based on the digital signal supplied from the time digital converter 41, and stores the histogram in the SRAM 43. Figure 1 In the embodiment of the present invention, each pixel 30 in the light receiving unit 25 receives the first reflected light pulse signal and the second reflected light pulse signal in the first time range and the second time range, respectively. Therefore, the histogram generator 42 generates a first histogram that classifies the light reception frequency of the first reflected light pulse signal received in the first time range for each unit period, and generates a second histogram that classifies the light reception frequency of the second reflected light pulse signal received in the second time range for each unit period.

[0166] A plurality of time-to-digital converters 41 and a plurality of histogram generators 42 may be provided. For example, one pixel may be provided for each pixel 30, or one pixel may be provided for each pixel group 30 arranged in a column. The plurality of pixels 30 arranged in a two-dimensional direction, the time-to-digital converters 41, and the histogram generators 42 provided in the light receiving section 25 constitute a pixel array section 50. The details of the pixel array section 50 will be described later.

[0167] The SRAM 43 stores the histogram generated by the histogram generator 42 .

[0168] The distance measuring unit 44 includes a replica histogram generator 45 and an SRAM (storage unit) 46. The distance measuring unit 44 reads a plurality of histograms (in Figure 1 In the embodiment of the present invention, the first histogram and the second histogram) and the histogram is passed to the copy histogram generator 45.

[0169] The copy histogram generator 45 generates a copy histogram obtained by copying a plurality of histograms generated by the histogram generator 42. Figure 1 In the method, a first copied histogram obtained by copying a first histogram with a first number corresponding to a first time interval is generated, and a second copied histogram obtained by copying a second histogram with a second number corresponding to a second time interval is generated.

[0170] The SRAM 46 stores each replica histogram generated by the replica histogram generating section 45. The SRAM 43 and the SRAM 46 may be integrated together.

[0171] The distance measuring unit 44 performs various calculations such as centroid calculation and measures the distance of the object OBJ based on the light receiving time that matches the light receiving time corresponding to the peak position of two or more replica histograms including the first replica histogram and the second replica histogram generated by the replica histogram generator 45, or the light receiving time corresponding to the maximum peak position of a reconstructed histogram described later synthesized by aligning the interval counts of the two or more replica histograms. The distance measurement value as the measurement result of the distance measuring unit 44 is provided to the interface unit 28.

[0172] The interface unit 28 outputs the distance measurement value supplied from the distance measurement unit 44 to the AP 5 as an output signal OUT.

[0173] The AP 5 executes, for example, an operating system, various application software, etc. The AP 5 executes various calculation processes based on the distance measurement value sent from the light detection device 4. For example, the AP 5 generates a distance image indicating the position and movement of the object OBJ.

[0174] Figure 2A : is a diagram for explaining an overview of a ranging operation of a dToF scheme. Figure 2A In the embodiment, the light emitting device 3 intermittently emits a light pulse signal L1 to the object OBJa.

[0175] The time digital converter 41 performs a counting operation of light reception timing in synchronization with the light emission of the light emitting device 3. The light emitting device 3 and the time digital converter 41 are synchronized by the clock signal Vclk generated by the clock generating section 21. The time digital converter 41 changes the count code per unit time t in synchronization with the clock signal Vclk.

[0176] The light emitting device 3 performs light emitting operation at regular intervals in synchronization with the clock signal Vclk. Figure 2A In the embodiment of the present invention, the light emitting device 3 performs a light emitting operation at the light emitting timing Snd1. In addition, the next light emitting operation is performed at the light emitting timing Snd2 which is separated from the light emitting timing Snd1 by an interval of 16t, 16t being 16 times the unit time t. The count code of the time digital converter 41 may be reset or not reset at intervals of 16t according to the light emitting interval of the light emitting device 3. It should be noted that the light emitting interval only needs to be an integral multiple of 16 times the unit time t, but in this specification, in order to simplify the description, the embodiment in which the light emitting interval is 16 times the unit time t will be mainly described.

[0177] The light pulse signal L1 emitted at the light emission timing Snd1 is reflected by the object OBJa, and the reflected light pulse signal L2 from the object OBJa at the light reception timing Rcv1 is received by the pixel 30. A digital signal corresponding to the count code at the light reception timing Rcv1 is output from the time digital converter 41 to the histogram generator 42.

[0178] The histogram generator 42 divides the period between two light emission timings for each unit time t. Figure 2A In the embodiment of , the interval of 16t is divided into intervals b0 to b15. Whenever the light emission of the light pulse signal L1 and the light reception of the reflected light pulse signal L2 are repeated, the histogram generator 42 classifies the interval between the light emission timing and the light reception timing into any one of the binary bits b0 to b15, and sequentially updates the light reception frequencies cnt0 to Cnt15 in units of binary bits.

[0179] For example, Figure 2A As shown in , in the case where the interval between the light reception timing Rcv1 and the light emission timing Snd1 (light round trip interval d1) is an interval of 12t, the histogram generator 42 increases the light reception frequency Cnt12 of the interval b12 once.

[0180] Furthermore, the interval at which the light round-trip distance d1 is 12t strictly means that the interval between the light reception timing Rcv1 and the light emission timing Snd1 is greater than or equal to 12t and less than 13t.

[0181] Figure 2B is a simplified diagram for explaining the repeated ranging operation. Figure 2A The ranging operation shown. Figure 2B An example is shown in which reflected light is received from an object OBJa whose optical round-trip distance d1 is at an interval 12t.

[0182] In the case where the ranging operation in which the light round-trip interval d1 is an interval of 12t is repeated, the histogram generator 42 sequentially increases the light receiving frequency Cnt12 of the binary bit b12. Due to a slight shift in the light emission timing, a slight movement of the object OBJa, a ranging error caused by a slight shift in the light receiving timing, etc., the light receiving timing may be an interval different from the original interval 12t (for example, an interval of 11t or 13t). In this case, the histogram generator 42 increases the light receiving frequency Cnt11 of the binary bit b11, the light receiving frequency Cnt13 of the binary bit b13, and the like. Therefore, the histogram generator 42 generates a histogram HST having the light receiving frequency Cnt12 of the interval b12 as a peak value. The horizontal axis of the histogram HST represents the type of intervals b0 to b15, and the vertical axis represents the light receiving frequencies cnt0 to Cnt15.

[0183] The histogram HST is read from the histogram generator 42 to the distance measuring section 44 via the SRAM 43. The distance measuring section 44 detects the section b12 having the peak value of the histogram HST. The distance measuring section 44 performs distance measuring calculation such as centroid calculation based on the section b12 and calculates a distance measuring value.

[0184] Figure 2A An embodiment in which the interval between the two emission timings Snd1 and Snd2 is 16t is shown, but the present invention is not limited thereto. For example, in the case where the two emission timings are set to an interval of 14t, a histogram with a bin count of 14 is generated in the histogram generator 42. It should be noted that in this specification, the ranging process in the case where the histogram generator 42 generates a histogram with a bin count of 16 is referred to as 16Bin ranging. It should be noted that in this specification, 16Bin ranging may be referred to as Mod16. In addition, in 16Bin ranging, an interval of 16t divided into bins b0 to b15 is also referred to as one exposure rotation.

[0185] As mentioned above, in Figure 1 In the light emitting device 3, the first light pulse signal and the second light pulse signal having different light emission intervals are output in each of the first time range and the second time range. That is, the first histogram and the second histogram generated by the histogram generator 42 in the first time range and the second time range are histograms with different interval counts.

[0186] Figure 2CFIG. 1 is a simplified diagram showing a distance measurement operation in the case where the light round trip interval is longer than the light emission interval. Figure 2C In the embodiment, the light pulse signal L1 is emitted at the light emission timing Snd3, and the reflected light pulse signal L2 is received at the light reception timing Rcv2 between the light emission timing Snd4 and the light emission timing Snd5.

[0187] Figure 2C An embodiment in which 16Bin ranging is performed is shown. Figure 2C As shown, the real light round trip interval d2 is 45t. However, in the histogram generator 42, since the interval between the light receiving timing Rcv2 and the light emission timing Snd4 immediately before the light receiving timing Rcv2 (the virtual light round trip interval d3) is an interval of 13t, the light round trip interval is classified as b13, and the light receiving frequency Cnt13 of the interval b13 increases. Therefore, also in the distance measuring section 44, the distance measurement calculation may be performed based on the virtual light round trip distance d3, and an error may occur in the distance measurement value.

[0188] As described above, in the ranging method of the dToF scheme, when the light round trip interval is longer than the light emission interval, there is a situation where accurate ranging cannot be performed. The ranging system 1 according to each embodiment described below can solve this problem. In addition, the ranging system 1 according to each embodiment is configured so that the ranging range can be expanded while the interval count is small, and the ranging accuracy, that is, the resolution of the ranging can be improved.

[0189] The light detection device 4 of this embodiment receives a plurality of reflected light pulse signals L2 with different light emission intervals, and generates a histogram with different interval counts corresponding to each reflected light pulse signal L2. The distance measuring unit 44 copies and pastes the histograms with different light emission intervals, and then superimposes the histograms to generate a reconstructed histogram. The distance measuring unit 44 can specify the real light round trip interval by detecting the peak value of the reconstructed histogram. Figure 3 In the following, the detailed process contents of the distance measuring unit 44 will be described.

[0190] Figure 3 An embodiment is shown in which the light-emitting interval of the light-emitting device 3 is changed, and 16-bin ranging, 14-bin ranging, and 12-bin ranging are performed in sequence. In the 16-bin ranging, a histogram HSTa with a bin count of 16 is generated, in the 14-bin ranging, a histogram HSTb with a bin count of 14 is generated, and in the 12-bin ranging, a histogram HSTc with a bin count of 12 is generated.

[0191] Although in Figure 1 Not shown, but in Figure 3The light emitting device 3 in the embodiment includes three light emitting sections having different light emitting intervals. It should be noted that, without providing a plurality of light emitting sections, one light emitting section can switch the light emitting interval in three ways, and sequentially emit the light pulse signal L1 at the light emitting interval for 16Bin ranging, sequentially emit the light pulse signal L1 at the light emitting interval for 14Bin ranging, and sequentially emit the light pulse signal L1 at the light emitting interval for 12Bin ranging.

[0192] Figure 1 The replica histogram generator 45 generates replica histograms HSTCa, HSTCb and HSTCc corresponding to the histograms HSTa, HSTb and HSTc.

[0193] A duplicate histogram HSTCa is generated by copying the histogram HSTa corresponding to the luminous interval of 16Bin and tiling it in the time axis direction. A duplicate histogram HSTCb is generated by copying the histogram HSTb by the number corresponding to the luminous interval of 14Bin and tiling it in the time axis direction. A duplicate histogram HSTc is generated by copying the histogram HSTc by the number corresponding to the luminous interval of 12Bin and tiling it in the time axis direction. It should be noted that tiling is the process of arranging multiple duplicate histograms close to each other in the time axis direction. By tiling, the ranging range can be expanded. The ranging unit 44 generates a reconstructed histogram HSTL by combining the duplicate histogram HSTCa, the duplicate histogram HSTCb and the duplicate histogram HSTC.

[0194] When generating the reconstructed histogram HSTL, the copy histogram generator 45 needs to align the interval counts of the copy histograms HSTCa, HSTCb and HSTCc. Since the least common multiple of the interval counts of the histograms HSTa, HSTb and HSTc is 336, all interval counts of the copy histograms HSTCa, HSTCb and HSTCc are set to 336.

[0195] By duplicating the 16-grid histogram HSTa 21 times, the duplicated histogram HSTCa can increase its grid count to 336. Similarly, the duplicated histograms HSTCb and HSTc can increase their bin counts to 336 by duplicating the histograms HSTb and HSTc the number of times corresponding to their respective bin counts. As described above, the bin count of each of the histograms HSTa, HSTb, and HSTc is determined based on the luminous interval during ranging. Therefore, a duplicated histogram is generated by duplicating the histogram by the number corresponding to the luminous interval during ranging before duplication.

[0196] The distance measuring section 44 generates a reconstructed histogram HSTL having a bin count of 336 by superimposing the replica histograms HSTa, HSTb, and HSTc. An accurate distance measurement value can be calculated from the peak value of the reconstructed histogram HSTL. FIG. 4A to FIG. 4D is a diagram showing a specific embodiment of detecting an accurate ranging value using histograms HSTa, HSTb, and HSTc.

[0197] Figure 4A is an embodiment of performing 16Bin ranging on object OBJb. Figure 2C In the embodiment shown in , the real light round trip interval d2 of the object OBJb is an interval of 45t. At this time, the histogram generator 42 generates a histogram BHSTa having a bin count 16 having a peak value in the bin b13 based on the virtual light round trip interval d3a.

[0198] Figure 4B For Figure 4A An example of performing 14-bin ranging on the same object OBJb. Figure 4C FIG. 1 shows an embodiment of performing 12-bin distance measurement on object OBJb. Figure 4B and Figure 4C In, similar to Figure 4A , a histogram is generated based on the virtual light round trip intervals d3b and d3c, respectively. Figure 4B In , a histogram BHSTb with a bin count of 14 is generated, with a peak value in bin b3. Figure 4C , a histogram BHSTc with a bin count of 12 is generated, with a peak value in bin b9.

[0199] Figure 4D The copied histograms BHSTCa, BHSTCb, and BHSTCc are shown. The copied histograms BHSTCa, BHSTCb, and BHSTCc are obtained by copying the histograms BHSTa, BHSTb, and BHSTc, respectively, and collaging them in the time axis direction.

[0200] like Figure 4D As shown, each of the replica histograms BHSTCa, BHSTCb, and BHSTCc has a plurality of peak values. The replica histograms BHSTCa, BHSTCb, and BHSTCc generally have peak values ​​in the b45 interval. The interval b45 corresponds to Figures 4A to 4C In the case where the replicated histograms BHSTCa, BHSTCb, and BHSTCc are superimposed to create a reconstructed histogram, the reconstructed histogram has a peak value in interval b45. In this specification, the peak value corresponding to the real light round trip interval is also referred to as a real peak value. Figure 4DAs shown, the replica histograms BHSTCa, BHSTCb and BHSTCc have one or more peaks in addition to the true peak. In this article, one or more peaks in addition to the true peak are also referred to as false peaks.

[0201] Similar to Figure 4D The embodiments described in Figure 3 The reconstructed histogram HSTL shown in FIG. 4 also has a peak value in a section corresponding to the real light round-trip interval of the object OBJ. Therefore, the distance measuring unit 44 can specify the real light round-trip interval by detecting the peak value of the reconstructed histogram HSTL.

[0202] Figure 5A is a schematic flow chart of the distance measurement process performed by the distance measurement system 1 according to the present embodiment. First, the light emitting device 3 emits a light pulse signal L1. Figure 1 In the embodiment of FIG. 1 , for example, the first light emitting unit 11 irradiates the object OBJ with a first light pulse signal emitted at a first time interval (step S1 ).

[0203] Then, the pixel 30 receives the first reflected light pulse signal reflected from the object OBJ (step S2 ). Then, the time-to-digital converter 41 generates a digital signal corresponding to the light receiving time of the pixel 30 (step S3 ).

[0204] Next, the histogram generator 42 determines whether a specified number of measurements have been performed (step S4). Note that the measurement means receiving the first reflected light pulse signal. When the number of measurements is less than the specified number of times, the process of steps S1 to S3 is repeated. When the number of measurements meets the specified number of times, the first histogram is generated based on the digital signal repeatedly output to the histogram generator 42 (step S5). The light receiving frequency information of each interval constituting the first histogram is stored in the SRAM 43. Note that in this specification, the time range from when the first light-emitting unit 11 performs the light-emitting operation for the first time in step S1 to when the first histogram is generated in step S5 is referred to as the first time range.

[0205] After step S5, it is determined whether measurement is performed at all lighting intervals (step S6). Subsequently, the lighting device 3 changes the lighting interval (step S7). Figure 1 The light emitting device 3 includes a second light emitting unit 12 that emits a second light pulse signal at a second time interval. Therefore, the light emitting device 3 stops the light emission of the first light emitting unit 11 and drives the second light emitting unit 12 that emits a second light pulse signal at a second time interval.

[0206] Similarly, in the second light emitting section 12, the light receiving section 25 repeatedly performs measurement within the second time range, and the histogram generator 42 generates a second histogram. In step S6, in the case where the light emitting device 3 can emit light at time intervals different from the first time interval and the second time interval, the light emitting device 3 changes the light emitting interval in step S7, and then repeatedly performs measurement to generate a separate histogram. When the measurement of all light emitting intervals that the light emitting device 3 can perform is completed, the distance measurement calculation is performed (step S8).

[0207] Figure 5B It is shown Figure 5A The flowchart of the distance measurement calculation in step S8 is shown in FIG. First, the distance measurement unit 44 reads two or more histograms including the first histogram and the second histogram from the SRAM 43. The replica histogram generator 45 generates two or more replica histograms including the first replica histogram and the second replica histogram (step S11). Figure 3 As shown, the first copy histogram and the second copy histogram are generated by copying and tiling the first histogram and the second histogram.

[0208] Subsequently, the distance measuring unit 44 generates a reconstructed histogram by superimposing two or more replica histograms including a first replica histogram and a second replica histogram (step S12). Superimposing two or more replica histograms means, for example, adding two or more replica histograms for each interval. The distance measuring unit 44 detects the peak value according to the generated reconstructed histogram (step S13). The distance measuring unit 44 performs centroid calculation based on the detected peak value (step S14). The distance measuring unit 44 obtains the distance value from the result of the centroid calculation (step S15).

[0209] Figure 6 1 is a diagram showing a case where 10Bin ranging, 12Bin ranging, 14Bin ranging, and 16Bin ranging are performed by the ranging system 1. In the 16Bin ranging, the exposure rotation Rt1 with the above-mentioned interval of 16t is repeated multiple times. For each exposure rotation Rt1, the light-emitting device 3 can emit light. In addition, the period of the multiple exposure rotations Rt1 can be set as the light-emitting interval PR11 of the light-emitting device 3. Similarly, also in the 14Bin ranging, the 12Bin ranging, and the 10Bin ranging, the exposure rotation Rt2 with an interval of 14t, the exposure rotation Rt3 with an interval of 12t, and the exposure rotation Rt4 with an interval of 10t are respectively repeated multiple times. In addition, the periods of the multiple exposure rotations Rt2, Rt3, and Rt4 can be set as the light-emitting intervals PR12, PR13, and PR14 of the light-emitting device 3, respectively. The light-emitting interval of the light-emitting device 3 is also called a pulse repetition interval (PRI). Furthermore, in this specification, since optical pulse signals of a plurality of PRIs are used, the ranging according to the first embodiment of the present disclosure may be referred to as multi-frequency ranging.

[0210] The exposure rotation Rt1 in the 16Bin range corresponds to Figure 5A The exposure rotation Rt1 is repeated multiple times, and Figure 5A In step S5, a histogram HSTd is generated. Similarly, 14-bin distance measurement, 12-bin distance measurement, and 10-bin distance measurement are performed in sequence, and histograms HSTe, HSTf, and HSTg are generated.

[0211] exist Figure 5B In step S11, based on the histograms HSTd, HSTe, HSTf and HSTg, the replica histograms HSTCd, HSTCe, HSTCf and HSTCg are generated. In step S12, based on the replica histograms HSTCd, HSTCe, HSTCf and HSTCg, a reconstructed histogram HSTLa is generated. In step S13, a peak value PeakLa is detected according to the reconstructed histogram HSTLa.

[0212] Hereinafter, the detailed operation of the distance measurement process will be described with reference to the detailed configuration of the pixel array section 50 . Figure 7 1 is a diagram showing a detailed first configuration example of the pixel array section 50 in the photodetection device 4 . Figure 7 The illustrated light detection device 4a includes a pixel array section 50a and a drive circuit 24a.

[0213] The driving circuit 24a includes a column selection circuit 62. Each pixel 30 in the pixel array section 50a is controlled by the column selection circuit 62. A plurality of column selection lines 63 extend from the column selection circuit 62 and are connected to the pixels 30. Although not shown, the column selection circuit 62 includes a shift register, an address decoder, and the like.

[0214] A plurality of pixels 30 are arranged in the light receiving section 25 along a row direction X (first direction) and a column direction Y (second direction), and have two or more pixels in each direction. The row direction X is a direction in which a plurality of column selection lines 63 are arranged. The column direction Y is a direction in which each column selection line 63 extends. In addition, in this specification, the two or more pixels 30 arranged along the row direction X are referred to as a first pixel group 51, and the two or more pixels 30 arranged along the column direction Y are referred to as a second pixel group 52. The plurality of first pixel groups 51 are arranged along the column direction Y, and the plurality of second pixel groups 52 are arranged along the row direction X.

[0215] The pixel array section 50a includes a plurality of time digital converters 41 and a plurality of histogram generators 42 arranged for each first pixel group 51. Note that the plurality of time digital converters 41 and the plurality of histogram generators 42 may be provided separately from the pixel array section 50a. For example, the plurality of time digital converters 41 and the plurality of histogram generators 42 may be provided on a chip different from the chip including the pixel array section 50a, and these chips may be bonded by Cu-Cu bonding or the like. The plurality of pixels 30 in the first pixel group 51 are connected to the time digital converters 41 and the histogram generators 42 via signal lines 61.

[0216] Figure 8 yes Figure 7 FIG. 5 is a timing chart of data transfer from the pixel array section 50 a to the SRAM 43 and the distance measuring section 44 in the first configuration embodiment. Figure 8 The pixel array section 50a performs 16Bin ranging, 14Bin ranging, 12Bin ranging and 10Bin ranging within different time ranges (ranging periods SFE1, SFE2, SFE3 and SFE4 described later) within one frame period FRMa, and transmits the light reception frequency data of each interval of each generated histogram to the ranging section 44.

[0217] exist Figure 8 In the embodiment of the present invention, the light emitting device 3 performs light emission at intervals of 16t, 14t, 12t, and 10t in 16Bin ranging, 14Bin ranging, 12Bin ranging, and 10Bin ranging, respectively. That is, each pixel 30 in the light receiving unit 25 receives more than two reflected light pulse signals L2, wherein more than two light pulse signals L1 emitted at more than two different time intervals are reflected by the object OBJ within more than two different time ranges.

[0218] In one frame period FRMa, a capture period CAP is provided for each of the second pixel groups 52. The column selection circuit 62 sequentially selects a plurality of second pixel groups 52. Figure 8 In the following, an embodiment will be described in which the second pixel group 52a is selected by the column selection circuit 62. The capture period CAP includes a capture setting period CSU and subframes SF1, SF2, SF3, and SF4. In addition, the subframe SF1 includes a distance measurement period SFE1 and a data output period DO1.

[0219] In the ranging period SFE1, 16-bin ranging is performed in the second pixel group 52a. The ranging period SFE1 includes a sub-frame setting process period SFSU and a plurality of mini-frames MF. The mini-frame MF includes Figure 6 The exposure rotation Rt1 and the transfer period TRN to the SRAM 43 are shown.

[0220] In the exposure rotation Rt1, each pixel 30 in the second pixel group 52a receives the reflected light pulse signal L2 having a light emission interval of 16t in parallel. In parallel, each pixel 30 inputs the corresponding light reception signal Vrcv to the corresponding time-to-digital converter 41.

[0221] In the transmission cycle TRN, each digital converter 41 to which each light reception signal Vrcv is input supplies a digital signal Vcnt corresponding to the light reception time of the reflected light pulse signal L2 to each histogram generator 42. Each histogram generator 42 generates a histogram with a bin count of 16 based on the supplied digital signal Vcnt, and stores the histogram in the SRAM 43.

[0222] In the data output period DO1 , the histogram generated by each histogram generator 42 is output from the SRAM 43 to the distance measuring section 44 .

[0223] As described above, in the mini frame MF within the ranging period SFE1, the corresponding pixels 30 of the second pixel group 52a at the left end of the pixel array section 50 sequentially receive the reflected light pulse signal L2, wherein the light pulse signal L1 emitted at the light emission interval corresponding to the 16-bin ranging is reflected in parallel by the object OBJ to generate a histogram. The light reception frequency data of each interval constituting the generated histogram is transferred to the SRAM 43 in the transfer period TRN.

[0224] A plurality of mini frame periods MF are provided in the ranging period SFE1. In each mini frame period MF, substantially the same operation is repeated. In some cases, the start code of the digital signal generated by the time digital converter 41 may be changed for each mini frame period MF.

[0225] Subsequently, in the distance measurement period SFE2 in the subframe SF2, 14-bin distance measurement in the second pixel group 52a is performed. The distance measurement period SFE2 includes a plurality of mini frames MF with an exposure rotation Rt2.

[0226] In the exposure rotation Rt2, each pixel 30 in the selected second pixel group 52a outputs a light receiving signal Vrcv corresponding to the reflected light pulse signal L2 with a light emission interval of 14t. That is, each pixel 30 in the selected second pixel group 52a sequentially outputs two or more light receiving signals Vrcv according to two or more reflected light pulse signals L2 within one frame period FRMa.

[0227] Each histogram generator 42 generates a histogram having a bin count 14 corresponding to the reflected light pulse signal L2 having a light emission interval of 14t in the SRAM 43 based on the supplied digital signal Vcnt. That is, the histogram generator 42 generates more than two histograms in which the light reception frequencies of more than two reflected light pulse signals L2 received within more than two time ranges are classified for each unit period.

[0228] Subsequently, in the ranging period SFE3 in the subframe SF3, 12Bin ranging in the second pixel group 52a is performed. In the data output period DO3, the data of the histogram with a bin count of 12 is output from the SRAM 43 to the ranging section 44. In the ranging period SFE4 in the subframe SF4, 10Bin ranging in the second pixel group 52a is performed. In the data output period DO4, the histogram with a bin count of 10 is output from the SRAM 43 to the ranging section 44.

[0229] The number of mini frame periods MF included in the ranging period SFE1 may be aligned with the number of other ranging periods SFE2, SFE3, and SFE4.

[0230] As described above, the second pixel group 52a includes a plurality of pixels 30 arranged in different first pixel groups 51. In the exposure rotations Rt1, Rt2, Rt3, and Rt4, the plurality of pixels 30 in the second pixel group 52a perform light receiving processing in parallel. Therefore, the light receiving signals Vrcv output from the plurality of pixels 30 in the second pixel group 52a are input in parallel to the plurality of time digital converters 41 arranged for each first pixel group 51. In addition, each of the plurality of time digital converters 41 sequentially generates a digital signal Vcnt corresponding to the light receiving time of the two or more reflected light pulse signals L2 received by each pixel 30 in the corresponding first pixel group 51. Each of the plurality of histogram generators 42 generates two or more histograms based on the digital signal Vcnt sequentially generated by the corresponding time digital converter 41.

[0231] When the photographing period CAP in the second pixel group 52a ends, the column selection circuit 62 selects the next second pixel group 52. Figure 8 In the embodiment of FIG. 5 , a light receiving operation is performed for each second pixel group 52 a arranged in the column direction Y in the pixel array section 50 , and two or more histograms are generated in parallel for each pixel 30 in the second pixel group 52 a .

[0232] Fig. 9 1 is a diagram showing a detailed second configuration example of the pixel array section 50 in the light detection device 4 . Fig. 9 The light detection device 4b shown has a pixel array section 50b and a drive circuit 24b. Figure 7The pixel array section 50 a in FIG. 5 , the pixel array section 50 b includes a time-to-digital converter 41 and a histogram generator 42 for each pixel 30 .

[0233] The driving circuit 24b includes Figure 7 The driving circuit 24 a includes a row selection circuit 64 in addition to the column selection circuit 62. A row selection line 65 extends from the row selection circuit 64 for each first pixel group 51 and is connected to each pixel 30.

[0234] Fig.10 yes Fig. 9 This is a timing diagram of data transmission from the pixel array section 50b to the SRAM 43 and the distance measuring section 44 in the second configuration embodiment. Figure 8 In the frame period FRMa in , a capture period CAP is provided for each second pixel group 52. On the other hand, in Fig.10 In the embodiment, each pixel 30 has one capture period CAP at a common timing in one frame FRMb.

[0235] exist Fig.10 In the frame FRMb period, each pixel 30 sequentially and in parallel performs the processes of 16Bin ranging, 14Bin ranging, 12Bin ranging and 10Bin ranging. That is, each of the plurality of pixels 30 sequentially outputs two or more light receiving signals Vrcv corresponding to two or more reflected light pulse signals L2 in one frame period FRMb. The output light receiving signal Vrcv of each pixel 30 is input in parallel to the corresponding time-to-digital converter 41.

[0236] Each of the multiple time digital converters 41 generates a digital signal Vcnt corresponding to the light reception time of more than two reflected light pulse signals L2 received by the corresponding pixel 30, and each of the multiple histogram generators 42 generates more than two histograms based on the digital signal Vcnt generated by the corresponding time digital converter 41.

[0237] like Fig.10 As shown, Figure 7 Compared with the light detection device 4a, the light detection device 4b does not need multiple capture periods CAP. Therefore, the light detection device 4b can perform distance measurement processing at a higher speed than the light detection device 4a. On the other hand, the light detection device 4a has fewer time-to-digital converters 41 and histogram generators 42 than the light detection device 4b, and does not need a row selection circuit 64. Therefore, the light detection device 4a has a simpler structure than the light detection device 4b and can be miniaturized.

[0238] Fig.11 2 is a flowchart showing the process of the distance measuring unit 44 . Fig.11 yes Figure 5B A more detailed flowchart of Figure 6 resemblance, Fig.11 An embodiment of performing 16Bin ranging, 14Bin ranging, 12Bin ranging, and 10Bin ranging is shown. Fig.11 In steps S21 to S28 shown, the processing is performed using the copy histogram generator 45 and the SRAM 46 in steps S21 to S26.

[0239] By referring to Figure 8 or Fig.10 The distance measurement process described above is performed by copying the histogram generator 45 received from the histogram generator 42. Figure 6 The four histograms shown are HSTd, HSTe, HSTf and HSTg.

[0240] As described above, in order to generate the reconstructed histogram, it is necessary to align the bin counts of the four replicated histograms HSTCd, HSTCe, HSTCf, and HSTCg corresponding to the four histograms HSTd, HSTe, HSTf, and HSTg.

[0241] exist Fig.11 In the embodiment of the present invention, the bin count of each replicated histogram can be aligned by setting the bin count of each replicated histogram to 1680, which is the least common multiple of 16, 14, 12, and 10. The configuration data of each replicated histogram is sequentially stored in the SRAM 46, and the reconstructed histogram is generated in the SRAM 46. As described above, the SRAM 46 stores the reconstructed histogram having the bin count corresponding to the least common multiple of more than two time intervals.

[0242] First, the copy histogram generator 45 clears the SRAM 46 and ensures the capacity of storing the reconstructed histogram (step S21). Next, the histogram HSTd with a bin count of 16 is copied and pasted to generate a copy histogram HSTCd, which is stored in the SRAM 46 (step S22).

[0243] Next, the histogram HSTe having a bin count of 14 is copied and tiled to generate a copied histogram HSTCe. In the SRAM 46, the copied histogram HSTCe is added to the copied histogram HSTCd (step S23).

[0244] Likewise, the copy histogram HSTCf and the copy histogram HSTCg are sequentially added to the histogram stored in the SRAM 46 (steps S24 and S25). Thus, the reconstructed histogram HSTLa is generated in the SRAM 46 (step S26).

[0245] The distance measuring section 44 detects the peak value of the reconstructed histogram HSTLa (step S27 ). Centroid calculation is performed based on the peak value obtained in step S27 to obtain a distance measurement value (step S28 ).

[0246] As described above, the optical detection device 4 of the present invention receives a plurality of reflected light pulse signals L2 having different light emission intervals, and generates two or more histograms having different interval counts. In addition, the optical detection device 4 copies, pastes, and superimposes the two or more histograms to generate a reconstructed histogram. By detecting the peak value of the reconstructed histogram, even when the light round-trip interval is longer than the light emission interval of the optical pulse signal L1, the true light round-trip interval can be obtained, and accurate distance measurement can be performed.

[0247] The light detection device 4 of the present disclosure can accurately perform distance measurement over a longer distance in a shorter exposure period. Figure 6 In the case of the distance measurement shown, each exposure period is 16t, 14, 12t and 10t, and the sum is 52t. At the same time, the interval count of the reconstructed histogram HSTLa is 1680. For distances where the light round trip period reaches 1680t and the exposure period is only 52t, accurate distance measurement is possible. In addition, the interval count required by the histogram generator 42 can also be reduced to 16 to 10, and the area of ​​the histogram generator 42 can be saved.

[0248] (Second Embodiment)

[0249] In a first embodiment, the detection of peak values ​​and the calculation of centroids are performed based on a reconstructed histogram having interval counts corresponding to the least common multiple of two or more time intervals. The reconstructed histogram is generated by copying, collaging, and superimposing each histogram generated for each time interval. Therefore, in the reconstructed histogram, the interval count can be reduced without reducing the amount of information of the histogram of the copy source.

[0250] Fig.12 2 is a diagram showing a distance measuring section 44 a and a peripheral section according to the second embodiment. The distance measuring section 44 a includes an interval extending section 71 , a peak detecting section 72 , a maximum peak detecting section 73 , a shifting section 74 , and a centroid calculating section 75 .

[0251] The interval expansion unit 71 reads a plurality of histograms from the SRAM 43. In addition, the interval expansion unit 71 stores the histogram corresponding to the maximum time interval as a unit in the SRAM 46. In addition, the histogram corresponding to two or more time intervals other than the maximum time interval is expanded into a unit and stored in the SRAM 46. Specifically, for Figure 6As shown in the histogram HSTd, the histogram HSTd with a bin count of 16 is stored as a unit in the SRAM 46. In addition, the histograms HSTe, HSTf, and HSTg are also expanded to a bin count of 16 and stored in the SRAM 46.

[0252] The SRAM 46 has a storage capacity corresponding to the bin count of the histogram corresponding to the above-mentioned maximum time interval.

[0253] Every time the interval expansion section 71 newly stores two or more histograms for one cell in the SRAM 46 , the peak detection section 72 performs processing of detecting positions where light reception times of peaks of the two or more histograms match each other in the storage area of ​​the SRAM 46 .

[0254] The maximum peak detection unit 73 detects the maximum value of the peak values ​​from the plurality of cells.

[0255] The shift unit 74 shifts the maximum value of the peak value to the center of the corresponding storage area of ​​the SRAM 46 .

[0256] The centroid calculation unit 75 calculates the centroid of the storage area of ​​the SRAM 46 shifted by the shift unit 74 .

[0257] Fig.13A , Fig. 13B as well as Fig. 13C is a diagram for explaining the operation of the distance measuring unit 44a. Figure 6 The process of detecting the peak value when the histograms HSTd, HSTe, HSTf and HSTg are superimposed.

[0258] like Fig.13A As described in Figure 6 The reconstructed histogram HSTLa in is divided into a plurality of unit histograms UHST, with the bin count 16 as one unit. The distance measuring section 44a repeats the process of detecting the peak value for each unit histogram UHST, and detects the maximum peak value from all the unit histograms UHST.

[0259] For each detection of a peak value, only one unit histogram UHST needs to be stored in the SRAM 46. That is, the unit histogram UHST in the SRAM 46 only needs to be overwritten each time a larger peak value is detected. Thus, the interval count of the histogram stored in the SRAM 46 can be reduced. Note that a wraparound number is assigned from 0 to each unit histogram UHST processed for each detection of a peak value. As described above, the wraparound number is an identification number that specifies any one of the multiple unit histograms UHST that constitute the reconstructed histogram.

[0260] Fig. 13B and Fig. 13C : is a flowchart showing the processing operation of the distance measuring section 44a according to the second embodiment.

[0261] Steps S31 to S37 are a process of detecting the peak value of the unit histogram UHST whose surround number is 0. In step S31, the distance measuring unit 44a specifies 0 as the surround number.

[0262] Steps S32 to S36 are a process in which the interval extension unit 71 generates the unit histogram UHST in the storage area of ​​the SRAM 46. In step S32, the SRAM 46 is cleared. In step S33, the histogram HSTd having a interval count of 16 is copied to the SRAM 46.

[0263] In step S34, the histogram HSTe with a bin count of 14 is extended to a bin count of 16 and is added to the histogram in the SRAM 46. Specifically, two histograms HSTe are copied, and bins b0 to b13 are extracted from one histogram HSTe. In addition, data of bins b0 and b1 are extracted from the other histogram HSTe, and are added to the previously extracted bins b0 to b13 as bins b14 and b15, respectively. As a result, the histogram HSTe is extended to a histogram of bins b0 to b15 and is added to the histogram in the SRAM 46.

[0264] Similarly, in step S35, the interval count 12 histogram HSTf is extended to the interval count 16 and added to the histogram in the SRAM 46. In step S36, the histogram HSTg is subjected to the same process as steps S34 and S35. As a result, a partially reconstructed histogram HSTLb is generated. The partially reconstructed histogram HSTLb corresponds to the unit histogram UHST of the encircling number = 0 included in the reconstructed histogram.

[0265] In step S37, the peak value detection unit 72 detects the peak value of the partial reconstruction histogram HSTLb. Fig. 13B In the embodiment, Max = 7) and the number of binary bits Bin for detecting the peak value (in Fig. 13B In the embodiment of , Bin = 2) is output to the maximum peak detection unit 73. In addition, the value of the surround number is output to the maximum peak detection unit 73 as a shift value.

[0266] Steps S41 to S47 are processes for detecting the peak value of the unit histogram UHST having the surround number 1. In step S41 , the distance measuring unit 44 a specifies the surround number 1. In steps S42 and S43 , the SRAM 46 is cleared and the histogram HSTd is copied to the SRAM 46 .

[0267] In step S44, the histogram HSTe with an interval count of 14 is shifted, extended to an interval count of 16, and added to the histogram in SRAM 46. Specifically, two histograms HSTe are copied, the data of the intervals b0 and b1 that have been extracted in step S34 are deleted from one histogram HSTe, and the data of the intervals b2 to b13 are extracted. In addition, the data of the intervals b0 to b3 are extracted from the other histogram HSTe. The intervals b2 to b13 extracted earlier are set as the histogram of the intervals b0 to b11, and the intervals b0 to b3 extracted next are added as the intervals b12 to b15. As a result, the histogram HSTe is shifted by the number of two intervals, extended to the histogram of the intervals b0 to b15 with four intervals added, and added to the histogram in SRAM 46.

[0268] Similarly, in step S45, the histogram HSTf of the bin count of 12 is shifted by the bin count extracted in step S35, extended to the bin count of 16, and added to the SRAM 46. In step S46, the histogram HSTg is subjected to the similar process as steps S44 and S45.

[0269] In step S47 , similarly to step S37 , the peak value of the partial reconstruction histogram HSTLb generated in the SRAM 46 is detected, and the peak value Max, the binary bit number Bin (Max=8, Bin=8) and the shift value are output to the maximum peak detection section 73 .

[0270] A similar process is repeated for the unit histogram UHST, where the wrap-around number is 2. That is, SRAM 46 is cleared. In addition, the histogram HSTd is copied to SRAM 46. Subsequently, a histogram expanded to the interval count 16 by shifting the histogram HSTe by the interval count extracted in step S45 is added to the histogram in SRAM 46. The histogram obtained by applying the same process to the histogram HSTe, HSTf as the histogram HSTd is added to the histogram in SRAM 46. The peak value detection processing of the calculated partial reconstruction histogram HSTLb is performed.

[0271] Similar processing is performed on the unit histograms UHST having the surround numbers 3 or greater included in the reconstructed histogram HSTLa.

[0272] Fig. 13C is a flowchart showing the process of the maximum peak detection section 73, the shift section 74 and the centroid calculation section 75. Fig. 13B After the process is executed Fig. 13C process.

[0273] like Fig. 13BAs shown, for a plurality of unit histograms UHST, the peak value Max, bin number Bin and shift value are repeatedly output to the maximum peak detection section 73. Based on this, the wrapping number of the unit histogram UHST having the maximum peak value Max is searched (step S51).

[0274] For example, Fig.13A FIG. 2 shows an embodiment in which the unit histogram USHT with the encircled number 3 is a unit histogram UHSTa having the maximum peak value Max. The unit histogram UHSTa has the maximum peak value Max in bin Bmax (in Fig.13A The maximum peak detection unit 73 outputs the surround number and the bin number Bina of the unit histogram UHSTa to the shift unit 74 (step S52).

[0275] In steps S53 to S58 , the shift section 74 generates a partial histogram HSTLc centered in the SRAM 46 such that the bin Bmax of the unit histogram UHSTa is located at the center of the 16-bin width.

[0276] In step S53, SRAM 46 is cleared. In step S54, histogram HSTd is shifted in SRAM 46 so that binBmax is located at the center of the 16-bin width. In step S55, for histogram HSTe, Fig. 13B When generating the unit histogram USHTa in the process of , a shift and expansion similar to that performed for HSTe is performed. Then, similar to step S54, binBmax is shifted so as to be located at the center of the 16 bin widths and added to the histogram in the SRAM 46.

[0277] In steps S56 and S57, a process similar to that in step S55 is performed on the histograms HSTf and HSTg. As a result, a partial histogram HSTLc centered so that the bin Bmax is located at the center of the 16-bin width in step S58 is generated in the SRAM 46.

[0278] The centroid calculation unit 75 performs centroid calculation on the partial histogram HSTLc (step S59). Based on the result of the centroid calculation, the distance measurement unit 44a outputs the distance measurement value to the interface unit 28 (step S60).

[0279] As described above, in the second embodiment, the distance value can be calculated by reducing the bin count of the histogram stored in the SRAM 46. Figure 6In the distance calculation processing of the histograms HSTd, HSTe, HSTf and HSTg in the first embodiment, the distance measuring unit 44 in the first embodiment needs to store the interval count 1680 of the reconstructed histogram HSTLa in the SRAM 46. On the other hand, the distance measuring unit 44a according to the second embodiment can reduce the interval count stored in the SRAM 46 to 16.

[0280] (Third Embodiment)

[0281] In the first embodiment, distance measurement calculations such as centroid calculations are performed inside the photodetection device 4. The distance measurement calculations may also be performed in the AP 5.

[0282] Fig.14A : is a block diagram showing a first configuration example of a distance measurement system according to the third embodiment. Figure 7 Compared with the light detection device 4a shown in the figure, the light detection device 4c does not have the distance measuring unit 44, but has a grouping generating unit 76. Fig.14A The AP 5a in FIG. 5 includes a distance measuring unit 77 .

[0283] The packet generation unit 76 generates distance measurement data to be transmitted from the light detection device 4c to the AP 5a. The distance measurement data generated by the packet generation unit 76 is transmitted to the AP 5a via the interface unit.

[0284] The AP 5a receives the distance measurement data transmitted via the interface unit 28. The distance measurement unit 77 acquires two or more histograms included in the distance measurement data and performs, for example, Fig.11 The ranging process is similar to the ranging process in the medium.

[0285] Fig. 14B is a block diagram showing a second configuration example of the distance measuring system according to the third embodiment. Fig. 14B The optical detection device 4d of the distance measuring system and Fig. 9 Similarly, a time-to-digital converter 41 and a histogram generator 42 are included for each pixel 30. In addition, Fig. 14B The light detection device 4d and Fig.14A Similarly, a packet generating unit 76 is provided.

[0286] Fig.15A 1 is a diagram showing a first embodiment of the distance measurement data generated by the packet generation unit 76 . Fig.15A The distance measurement data 80 shown includes a start portion 81 , a plurality of packets 82 , and an end portion 83 .

[0287] The start portion 81 has an identifier indicating a header of a frame and the number of two or more time intervals (specifically, light emission intervals of the light emitting device 3 ) during which the light emitting device 3 emits the optical pulse signal L1 .

[0288] Each packet 82 includes a header 84 including a bin count of a corresponding histogram among two or more histograms and the number of multiple pixels 30 in the pixel array section 50, histogram data 85 constituting the corresponding histogram, and a footer 86 including end information of the corresponding histogram. The histogram data 85 includes light reception frequency data for each bin constituting the corresponding histogram.

[0289] The end portion 83 has an identifier indicating the end of the frame.

[0290] Fig.15A The distance measurement data 80 in φ includes the number of groups 82 corresponding to the light emission intervals of the light emitting device 3 .

[0291] like Fig.15A As shown, the grouping generating unit 76 generates distance measurement data including two or more histograms in units of frames.

[0292] Fig. 15B It is shown Fig.15A Schematic diagram of the transmission order of the ranging data 80 in . Fig. 15B The distance measurement data 80 shown is as follows Figure 6 The embodiment shown is a case where distance measurement is performed at the lighting intervals of four light emitting devices 3. The distance measurement data 80 includes, as packets 82, a packet 82a representing 16-bin distance measurement data, a packet 82b representing 14-bin distance measurement data, a packet 82c representing 12-bin distance measurement data, and a packet 82d representing 10-bin distance measurement data.

[0293] The header 84 contains the bin count of the histogram in each range. Specifically, 16 is recorded as the binary bit count in the header 84 in the packet 82a.

[0294] The groups 82 a , 82 b , 82 c , and 82 d contain histogram data 85 a . The histogram data 85 a includes a histogram 87 generated for each pixel 30 .

[0295] A histogram 87 having a bin count of 16 is included in group 82a.

[0296] In the distance measurement data 80, the bin count of the histogram 87 is different between the packets 82a, 82b, 82c, and 82d. Therefore, the histogram data 85a of the distance measurement data 80 has a variable length, and the data transmission amount can be minimized.

[0297] In the ranging data 80, the packet 82 may have a fixed length. Fig. 15C8 is a diagram showing the transmission order of the distance measurement data 80 in which the packet 82 has a fixed length. Specifically, the packet 82e indicating 14Bin distance measurement, the packet 82f indicating 12Bin distance measurement, and the packet 82g indicating 10Bin distance measurement include the histogram data 85b. In the histogram data 85b, the padding part 88 is added to the histogram 87.

[0298] In the case of the grouping 82e, the padding section 88 adds padding data for two bin counts to each histogram 87, and the bin count is 14. For example, 0 is added as the padding data.

[0299] exist FIG. 15A to FIG. 15C In the distance measurement data 80 shown, a separate group 82 is provided for each lighting interval of the lighting device 3. For example, Fig. 14B The light detection device 4b shown can sequentially perform the distance measurement process for each light emission interval of the light emitting device 3. In addition, the light detection device 4b can generate a histogram for each pixel 30. In this case, the packet generation section 76 can generate the packet 82 in the data transmission order. That is, there is no need to rearrange the histogram data and the like in the packet generation section 76, and the distance measurement data can be generated at a high speed.

[0300] Meanwhile, when performing the distance measurement calculation for each pixel 30 , the distance measurement section 77 in the AP 5 a needs to extract the data of the pixel 30 to be subjected to the distance measurement calculation from the plurality of groups 82 .

[0301] The grouping generation section 76 may rearrange the histogram data for each pixel 30 . Fig.16A 2 is a diagram showing a second example of distance measurement data generated by the packet generation unit 76 . Fig.16A The distance measurement data 90 shown includes a start portion 91 , a plurality of packets 92 , and an end portion 93 .

[0302] The start portion 91 has an identifier indicating a header of a frame, the number of the plurality of pixels 30 , and the number of two or more time intervals (light-emission intervals of the light-emitting device 3 ).

[0303] The packet 92 includes a header 94 including information indicating the position of the pixel 30, histogram data 95 constituting a corresponding histogram of the two or more histograms, and a trailer 96 including end information of the corresponding histogram.

[0304] The end portion 93 has an identifier indicating the end of the frame.

[0305] Fig. 16B 2 is a diagram showing the transmission order of the ranging data 90 . Fig. 16B The distance measurement data 90 shown is as follows Figure 6The illustrated embodiment is a case where distance measurement is performed at the lighting intervals of four light emitting devices 3. The distance measurement data 90 includes a group 92 for each pixel 30.

[0306] The histogram data 95 includes a histogram 97a with a bin count of 16, a histogram 97b with a bin count of 14, a histogram 97c with a bin count of 12, and a histogram 97d with a bin count of 10. The histogram data 95 has a fixed length.

[0307] As described above, in the third embodiment, in order to set the distance measuring unit 77 in the AP 5a, the distance measuring data including the histogram data is sent from the light detecting devices 4c and 4d to the AP 5a. As a result, similar to the first and second embodiments, the distance measuring unit 77 can generate more than two replica histograms and reconstruction histograms, and can accurately measure the distance of the object OBJ from the peak position. In the third embodiment, since it is not necessary to set the distance measuring unit in the light detecting devices 4c and 4d, the structure of the light detecting device 4 can be simplified, and the miniaturization of the light detecting device 4 can be achieved. In addition, in the above-mentioned first and second embodiments, it is necessary to set the distance measuring unit in the light detecting device for generating more than two replica histograms and reconstruction histograms, and to set a processor with high-performance processing capabilities in the light detecting device. On the other hand, in the third embodiment, since the two or more replica histograms and reconstruction histograms are originally generated by the AP 5 with high-performance processing capabilities, it can be implemented without changing the hardware of the existing distance measuring system.

[0308] (Fourth Embodiment)

[0309] In the first to third embodiments, the start code of the time digital converter 41 is fixed for each exposure rotation. On the other hand, in the fourth embodiment described below, the ranging accuracy is improved by changing the start code of the time digital converter 41 for each exposure rotation.

[0310] like Fig.17A As shown, in the case where the interfering radio wave is synchronized with the processing cycle such as exposure rotation (the frequency of the interfering radio wave f=1 / processing cycle), the interfering radio wave as a standing wave can be used to modulate the count. Therefore, due to the influence of noise caused by the interfering radio wave, a pseudo peak as shown in the histogram HSTh may occur.

[0311] on the other hand, Fig. 17B An embodiment is shown in which the start code of the time-to-digital converter 41 is changed for each processing cycle. Fig. 17B An embodiment of a 13-bin range generating a histogram with 13 bins is shown, but the bin count of the histogram is arbitrary. Fig. 17BIn the embodiment of the present invention, the start code of the time digital converter 41 is set to 0 in the first exposure rotation. That is, in the first exposure rotation, the count code of the time digital converter 41 is incremented from 0 to 12 to generate the histogram HSTi. Subsequently, in the second exposure rotation, the start code of the time digital converter 41 is set to, for example, 11. That is, in the second exposure rotation, after the count code is incremented from 11 to 12, the count code is reset to 0, and the count code is incremented from 0 to 10 to generate the histogram HSTj. As a result, the position of the pseudo peak caused by the interfering radio wave can be shifted.

[0312] Similar to the histograms HSTi and HSTj, a plurality of histograms in which the start code of the time digital converter 41 when generating the histograms is periodically shifted are generated and superimposed, whereby pseudo peaks can be dispersed. Fig. 17B As shown in the reconstructed histogram HSTLd on the right side of , a reconstructed histogram obtained by flattening portions other than the peaks of the histograms HSTi and HSTj can be generated.

[0313] Note that the histogram HSTj is shifted by the start code of the time-to-digital converter 41 and is superimposed on Fig.11 or FIG. 13A to FIG. 13C The histogram adding process in the distance measuring unit 44 is shown in FIG.

[0314] In this specification, the process of periodically shifting the start code of the time digital converter 41 and flattening the pseudo peak caused by the above-mentioned interfering radio wave is referred to as linear correction.

[0315] Here, the period of linear correction needs to match the period of ranging. Specifically, in 16-bin ranging, a linear correction of a 16-bin period needs to be performed.

[0316] Fig.18A An embodiment is shown in which the same number of exposures is performed without performing linear correction in, for example, 16-bin ranging and 14-bin ranging. In this case, pseudo peaks caused by interfering radio waves cannot be flattened in the histogram HSTk of 16-bin ranging and HSTl of 14-bin ranging, and in the reconstructed histogram HSTLe obtained by copying and superimposing the histograms HSTk and HSTl. Therefore, ranging accuracy deteriorates. At the same time, Fig.18A Since the number of exposures in 16-Bin ranging and 14-Bin ranging is the same, that is, the exposure amount is constant in 16-Bin ranging and 14-Bin ranging, the difference in signal amount between the maximum peak value of the reconstructed histogram and the second peak and subsequent peak values ​​increases, and the probability of successful ranging increases.

[0317] At the same time, even in the case where the number of exposures is different between 16-bin ranging and 14-bin ranging, the ranging accuracy is reduced. For example, in the case where a linear correction of a 16-bin cycle is performed for 10 cycles within a 16-bin range, the number of exposures is 160 times. In addition, in the case where a linear correction of a 14-bin cycle is performed for 10 cycles within a 14-bin range, the number of exposures is 140 times. When the same number of cycles of linear correction are performed in 16-bin ranging and 14-bin ranging, a difference in the number of exposures occurs.

[0318] Fig.18B An embodiment in which the same number of cycles of linear correction are performed in 16-bin ranging and 14-bin ranging is shown. Since the number of exposures is different, there is a difference in the number of light reception times (signal amount) for generating the histogram between the histogram HSTm of 16-bin ranging and the histogram HSTn of 14-bin ranging.

[0319] In the reconstructed histogram HSTLf (in which the histograms HSTm and HSTn are superimposed), the peak of the histogram HSTm can be obvious and the ranging accuracy is improved. However, since the number of exposures is different between the 16-bin ranging and the 14-bin ranging, the difference in the signal amount between the maximum peak value and the second peak and subsequent peak values ​​in the reconstructed histogram HSTLf is reduced, and the success probability of ranging is reduced.

[0320] Fig.18C An embodiment in which linear correction is performed in 16-bin ranging and 14-bin ranging and the number of exposures is added is shown. In the histogram HSTo of 16-bin ranging and the histogram HSTp of 14-bin ranging, the pseudo peak caused by the interfering radio wave is flattened, and the number of light receptions of the peak values ​​is substantially matched. As a result, in the reconstructed histogram HSTLg in which the histograms HSTo and HSTp are superimposed, the peak values ​​become obvious, and the ranging accuracy can be improved. In addition, in Fig.18A In the process, since the exposure is constant in 16-bin distance measurement and 14-bin distance measurement, the probability of successful distance measurement also increases.

[0321] If the number of exposures is set as the number according to the least common multiple of the period of each ranging, the number of exposures can be matched by multiple Bin ranging. Specifically, when performing 16Bin ranging, 14Bin ranging, 12Bin ranging, and 10Bin ranging, the number of exposures for each ranging can be matched with the least common multiple of 1680 of each interval count 16, 14, 12, and 10. That is, by performing 16Bin ranging 105 times, 14Bin ranging 120 times, 12Bin ranging 140 times, and 10Bin ranging 168 times, it is possible to match the number of exposures for each Bin ranging, that is, to make the exposure amount constant.

[0322] Fig.19 1 is a diagram showing an example of a ranging period SFE1 of 16-bin ranging in the fourth embodiment. Figure 8 As shown, the ranging cycle SFE1 includes a plurality of exposure rotations Rt1. Fig.19 In the embodiment, 16 exposure rotations Rt1 are set as one cycle. In one cycle, the start code of the time digital converter 41 is changed for each exposure rotation Rt1 to perform linear correction. By repeating the cycle including this linearity correction 105 times (cycle 1 to cycle 105), the number of exposures can be set to 1680. The same applies to 14Bin ranging, 12Bin ranging, and 10Bin ranging.

[0323] As described above, in the fourth embodiment, the start code of the time digital converter 41 is periodically shifted to perform linear correction for flattening the pseudo peak caused by the interfering radio wave, and the number of exposures for each distance measurement is matched with each other. Thereby, the success rate of distance measurement is improved, and the accuracy of distance measurement is improved. The fourth embodiment can be applied to any one of the first to third embodiments.

[0324] (Fifth Embodiment)

[0325] In the first to fourth embodiments, the method for detecting one peak value from the reconstructed histogram has been described. It is also possible to detect a plurality of peak values ​​from the reconstructed histogram. The fifth embodiment is effective for performing distance measurement of a plurality of objects OBJ and the like.

[0326] Fig. 20A 1 is a diagram showing an embodiment of detecting a first peak value and a second peak value in 16Bin ranging, 14Bin ranging, 12Bin ranging, and 10Bin ranging, respectively. That is, Fig. 20A FIG. 4 shows an embodiment of receiving reflected light pulse signals L2 from two objects OBJ. Fig. 20A As shown, the histogram HSTq in each range measurement has a first peak value Peak1 and a second peak value Peak2. In the reconstructed histogram HSTLh, in addition to the first peak value PeakL1, there are multiple intervals (eg, DPeakL) in the histogram HSTq that are affected by the first peak value Peak1.

[0327] Fig. 20B Is used to explain the Fig. 20A The figure shows the reason why the interval affected by the first peak value Peak1 appears. To simplify the description, Fig. 20BAn embodiment of generating a reconstructed histogram HSTLi by combining a copy histogram obtained by copying and tiling a histogram generated by 16Bin ranging and a copy histogram obtained by copying and tiling a histogram generated by 14Bin ranging is shown. Fig. 20B In the reconstructed histogram HSTLi in , the components of the first peak value Peak1 appear in multiple intervals. In this case, the second peak value Peak2 may not be correctly detected.

[0328] Fig. 20C 1 is a diagram for explaining the processing operation of the distance measuring device according to the fifth embodiment. Fig. 20C As shown, after detecting the first peak value Peak1, a histogram HSTr is generated, wherein the component of the first peak value Peak1 is deleted from each of the histograms of 16Bin ranging, 14Bin ranging, 12Bin ranging, and 10Bin ranging in ranging. By copying, collage, and superimposing these histograms HSTr to generate a reconstructed histogram HSTLj, the second peak value PeakL2 can be detected without being affected by the first peak value Peak1. Fig.20D It is shown in Fig. 20B The example of the newly generated reconstructed histogram after deleting the component of the first peak value Peak1 from the copied histogram is shown in FIG. Fig. 20B Compared with the reconstructed histogram HSTLi in , the second peak value PeakL2 is the peak value of the reconstructed histogram HSTLk.

[0329] Fig.21 4 is a flowchart illustrating the processing of the distance measuring unit 44 in the fifth embodiment. Fig.21 In steps S71 to S86 shown in the figure, the process for detecting the first peak will be described. In addition, in steps S91 to S106, the process for detecting the second peak will be described.

[0330] In step S71, the light emitting device 3 and the like are driven to start the distance measurement process. The light detection device 4 performs distance measurement in the first interval counting cycle (e.g., 16-bin distance measurement), and stores the histogram generated by the histogram generator 42 in the first memory (area of ​​the SRAM 43) (steps S72, S73). Similarly, in steps S74 and S75, the histogram generated in the second interval counting cycle (e.g., 14-bin cycle) is stored in the second memory in the SRAM 43.

[0331] This is performed for all lighting intervals, and in steps S75 and S76 , the histogram generated in the nth interval counting cycle is stored in the nth memory in the SRAM 43 .

[0332] In steps S81 to S85, the Fig.11 or FIG. 13A to FIG. 13C In step S86, the interval of the reconstructed histogram having the first peak is obtained. In step S87, it is determined whether the second peak value is obtained, and in the case of obtaining the second peak value, the process proceeds to step S91.

[0333] In steps S91 to S94 , the signal amount to be deleted when deleting the first peak is determined from the histogram or the like acquired in step S73 .

[0334] In step S91, a bin corresponding to the bin of the reconstructed histogram having the first peak value acquired in step S86 is acquired from the histogram stored in the first memory. In addition, the signal amount of a binary bit is acquired.

[0335] In steps S92 to S94, similar processing as in step S91 is performed on each of the histograms acquired in steps S74 to S77. As a result, the signal amount of the interval corresponding to the first peak can be acquired from each histogram. In step S94, the minimum signal amount among the acquired signal amounts is set as the signal amount of the first peak.

[0336] In steps S101 to S105, a reconstructed histogram is generated similarly to steps S81 to S85. However, before tiling, the first peak is deleted from the histogram.

[0337] Specifically, the process in step S101 will be described. With respect to the histogram stored in the first memory, the signal amount of the first peak obtained in step S94 is subtracted from the signal amount of the bin corresponding to the first peak found in step S91. Thereafter, processing similar to the process in step S81 is performed.

[0338] In step S106, the second peak value is acquired similarly to step S86. In step S107, it is determined whether to acquire the third peak value, and in the case of acquiring the third peak value, the process proceeds to the acquisition processing of the third peak value (not shown). In addition, in the process of acquiring the third peak value, similar to the process of acquiring the second peak value, a process of reducing the signal amount of the binary bit corresponding to the second peak value from the histogram stored in the first memory or the like is performed.

[0339] As described above, in the fifth embodiment, after obtaining the first peak value from the reconstructed histogram, a reconstructed histogram with the first peak value deleted is generated, so that the true second peak value can be correctly detected without being affected by the first peak value. Therefore, the ranging system 1 can perform ranging for multiple objects OBJ arranged in different places in one ranging sequence. The fifth embodiment can be applied to any one of the first to fourth embodiments.

[0340] (Sixth Embodiment)

[0341] In the time-to-digital converter 41 of the present disclosure, Gray code may be used in order to suppress power fluctuation due to propagation of the count signal. Fig. 22 2 is a diagram showing a time-to-digital converter 41 a and a histogram generator 42 a in the sixth embodiment. Fig.23 is a diagram showing a Gray code output from a Gray code counter described later.

[0342] Gray code includes Fig.23 The plurality of bits shown, and only one of the plurality of bits is switched. Since each bit of the Gray code is connected to a separate wiring, by using the Gray code, the bit switching amount when the Gray code is switched can be minimized and power consumption can be reduced.

[0343] The time-to-digital converter 41 a includes a Gray code counter 101 and a plurality of latch sections 102 . The histogram generator 42 a includes a grayscale-to-thermal (GT) conversion section 103 and a bin counter 104 .

[0344] The pixel 30 includes a pixel circuit including a photoelectric conversion element 105 such as a SPAD. The photoelectric conversion element 105 generates charges corresponding to received light. The pixel circuit supplies a light reception signal Vrcv corresponding to the charges generated by the photoelectric conversion to the time-to-digital converter 41a.

[0345] Gray code counter 101 outputs a 4-bit Gray code to a plurality of latch sections 102 based on, for example, a measurement start signal and a clock signal Vclk provided from distance measurement control section 26. Fig.23 shown.

[0346] The plurality of latch sections 102 latch the Gray code at the timing when the light reception signal Vrcv is supplied from the pixel 30. The latched Gray code is supplied to the histogram generator 42a as the digital signal Vcnt.

[0347] The GT conversion unit 103 of the histogram generator 42a has a plurality of conversion tables that differ according to the cycle of the exposure rotation, and converts the Gray code into light reception time data. The GT conversion unit 103 converts the Gray code acquired from the latch unit 102 using the conversion table corresponding to the cycle of the exposure rotation at that time to acquire the interval number. The GT conversion unit 103 supplies the counter increment signal Vinc to the binary bit counter 104 corresponding to the acquired binary bit number.

[0348] Each interval counter 104 increments the count value when the corresponding counter increment signal Vinc is provided.

[0349] As described above, when the histogram generator 42a generates a histogram, in order to generate light receiving frequency data, it is necessary to process the amount of accumulated light receiving data for each interval. When the light receiving data of each interval is sent to the histogram generator 42a, by using Gray code, the signal migration amount between the time-to-digital converter 41a and the histogram generator 42a can be reduced, and power consumption can be suppressed.

[0350] Since the binary bit counts to be used are different in 16-bin ranging, 14-bin ranging, 12-bin ranging, and 10-bin ranging, different continuous ranges are used within the conversion range of the 4-bit Gray code in each Bin ranging, such as Fig.23 In 16Bin ranging, use Fig.23 16 Gray codes in the transition range of Bin numbers 0 to 15 in the other Bin ranging are used. In other Bin ranging, a continuous range of a partial transition range of the Gray code used in 16 Bin ranging is used, and the serial number of Bin number 0 is assigned to the Gray code in the continuous range for use.

[0351] Fig.24A The conversion range of the Gray code corresponding to the 14-bin ranging is shown in FIG. In the 14-bin ranging, the time-to-digital converter 41a uses Fig.23 The continuous range of Gray codes 0001 to 1001 in the histogram generator 42a is obtained, and Bin numbers 0 to 13 are assigned to this continuous range. Therefore, according to the conversion table of the 14-bin range included in the GT conversion unit 103 in the histogram generator 42a, Fig.24A The 14 Gray codes in are associated with 14 bin counters 104 corresponding to Bin numbers 0 to 13.

[0352] Similarly, Fig. 24B is a diagram showing the conversion range of the Gray code corresponding to the 12-bin ranging, and Fig.24C 1 is a diagram showing the conversion range of the Gray code corresponding to the 10Bin ranging. Similar to the conversion table corresponding to the 14Bin ranging, the conversion table corresponding to the 12Bin ranging or the conversion table corresponding to the 10Bin ranging will be Fig. 24B or Fig.24C The Gray code in is associated with a 12 or 10 binary bit counter 104.

[0353] As described above, in the sixth embodiment, since the Gray code counter 101 is provided in the time digital converter 41a and the GT conversion unit 103 is provided in the histogram generator 42a, the signal conversion amount of the digital signal in each interval from the time digital converter 41a to the histogram generator 42a can be minimized, the fluctuation of the power supply voltage can be suppressed, and the power consumption can be reduced.

[0354] (Seventh Embodiment)

[0355] In the first to sixth embodiments, the true peak is extracted based on the reconstructed histogram. In addition, in the first to sixth embodiments, two or more replica histograms are added for each interval to generate the reconstructed histogram, but the reconstructed histogram may be generated by another method.

[0356] like Figure 4D As shown, the true peak exists at the position where all the replicated histograms have peaks. At the same time, the false peak exists at the position where at least one replicated histogram does not have a peak. Based on these characteristics, the true peak can be searched.

[0357] Fig.25A is a diagram for explaining the generation of a reconstructed histogram according to the seventh embodiment. Fig.25A On the left side of , four replicated histograms GHSTa, GHSTb, GHSTc, and GHSTd are shown. Each of the replicated histograms GHSTa, GHSTb, GHSTc, and GHSTd is obtained by tiling (copying) a plurality of histograms generated by ModA, ModB, ModC, and ModD of four different Bin cycles. As described above, all four replicated histograms have the same bin count. The horizontal axis of each replicated histogram GHSTa to GHSTd represents the bin number (Bin), and the vertical axis represents the count value (Count) of each bin number.

[0358] In addition, Fig.25A On the right side of the figure, count order histograms SHST1, SHST2, SHST3, and SHST4 are shown, wherein the count values ​​of each interval of the four replicated histograms GHSTa to GHSTd are arranged in the order of amplitude. The horizontal axis of the count order histograms SHST1 to SHST4 indicates the interval number (Bin), and the vertical axis indicates the count value (Count) of each interval number. The count value of each interval of the replicated histograms GHSTa to GHSTd is assigned to any one of the count order histograms SHST1 to SHST4 in the order of amplitude. That is, the count order histogram SHST1 is generated by collecting the maximum count value of each interval, the count order histogram SHST2 is generated by collecting the second maximum count value of each interval, the replicated histogram STT3 is generated by collecting the third maximum count value of each interval, and the replicated histogram STT4 is generated by collecting the minimum count value of each interval.

[0359] For example, in the copy histograms GHSTa, GHSTb, GHSTc, and GHSTd, segments bHSTa, bHSTb, bHSTc, and bHSTd having the same number of segments are included. Among the intervals bHSTa-bHSTd, the interval bHSTd having the maximum count value is assigned to the count order histogram SHST1, the interval bHSTc having the second count value is assigned to the count order histogram SHST2, the interval bHSTa having the third count value is assigned to the count order histogram SHST3, and the interval bHSTb having the minimum count value is assigned to the count order histogram SHST4. Since the interval bHSTd is a peak in the copy histogram GHSTd, the peak value appears in the corresponding interval of the count order histogram SHST1. At the same time, since the interval bHSTb is not a peak value in the copy histogram GHSTb, no peak value appears in the corresponding interval of the count order histogram SHTS4.

[0360] Fig.25B It is shown Fig.25A A diagram showing the relationship between the replication histograms GHSTa to GHSTd and the count order histograms SHST1 to SHST4 shown in FIG. Fig.25B In the replicated histograms GHSTa to GHSTd, the first peak PHSTTa1 (A) of ModA, the first peak PHSTb1 (B) of ModB, the first peak PHSTc1 (C) of ModC, and the first peak PHSTd1 (D) of ModD are shown. The first peak is the maximum count value in the same interval of the replicated histograms GHSTa to GHSTd. As described above, a plurality of first peaks PHSTa1 to PHSTd1 may exist in each replicated histogram GHSTa to GHSTd. In addition, Fig.25B The true first peak PHST1 is shown.

[0361] The timing at which the first peaks of all MODs are aligned is the true first peak. In this embodiment, the true first peak is detected by using the count order histogram in which the peak appears in all MODs and the count value of the peak is the smallest as the reconstructed histogram RHST.

[0362] Since the bin having the maximum count value is assigned to the count order histogram SHST1, many of the first peaks PHSTa1 to PHSTd1 appear on the count order histogram SHST1. In addition, true peaks and false peaks are mixed in the count order histogram SHST1.

[0363] In the count order histogram SHST2 to which the interval with the second count value is assigned, if there is no peak with the second count value, no peak appears. Therefore, in the count order histogram SHST2, no peak appears unless there are at least two peaks at the same interval number. Similarly, in the count order histogram SHST3, no peak appears unless there are at least three peaks at the same interval number.

[0364] In the count order histogram SHST4, a peak value appears only when all the replicated histograms GHSTa to GHSTd have the same number of bins. Figure 4D The peak in the count order histogram SHST4 described in is a true peak. Therefore, the reconstructed histogram RHST can be generated based on the count order histogram SHST4 to which the bin having the minimum count value is assigned.

[0365] In addition, Fig.25B In the replicated histograms GHSTa, GHSTb, GHSTc and GHSTd of , the second peak PHSTa2(A') of ModA, the first peak PHSTb2(B') of ModB, the first peak PHSTc2(C') of ModC and the first peak PHSTd2(D') of ModD are shown respectively. The timing of aligning the second peaks of all MODs is the true second peak. Similarly, the true second peak PHST2 can be detected on the count order histogram SHST4 based on the second peaks PHSTa2, PHSTb2, PHSTc2 and PHSTd2. Note that, as shown in FIG. FIG. 20A to FIG. 20C As described, the detection process of the true second peak PHST2 can be performed in a state where the influence of the first peaks PHSTa1 to PHSTd4 is removed from the replica histograms GHSTa to GHSTd in advance.

[0366] It should be noted that in the reconstructed histogram RHST, the count value of the true first peak is greater than the count value of the true second peak.

[0367] like Fig.25B As described, in the seventh embodiment, the same interval in which each of the two or more replicated histograms GHSTa to GHSTd has a peak value of the light receiving frequency is searched, and a reconstructed histogram RHST is generated based on the minimum count value (peak value) in the search interval. In this specification, the scheme for generating a reconstructed histogram RHST with a minimum count value as described above is referred to as a minimum count picking (LCP) scheme. In addition, in the first to sixth embodiments, the scheme for adding two or more replicated histograms for each interval to generate a reconstructed histogram is referred to as an adding scheme.

[0368] and Figure 6Compared with the reconstructed histogram HSTLa in Fig.25A The influence of false peaks is removed from the reconstructed histogram RHST in , so the true peaks (true first peak PHST1 , true second peak PHST2 , and true third peak PHST3 ) can be accurately detected.

[0369] Fig.26 1 is a block diagram showing the configuration of the distance measuring section 44b according to the seventh embodiment. The distance measuring section 44b includes a minimum search section (min-search) 111, a plurality of weighting sections 112, and a storage section 113. The minimum search section 111 and the plurality of weighting sections 112 are arranged, for example, in the replica histogram generator 45. The storage section 113 is provided in the SRAM 46, for example.

[0370] The distance measuring section 44b inputs the data of each section from the plurality of storage sections 114. The plurality of storage sections 114 are memories that store data of each section generated by a range of different Bin cycles, and are arranged in the SRAM 43, for example. Fig.26 In the embodiment of , four storage sections 114 corresponding to ModA to ModD are included. The storage section 114 corresponding to ModA stores a count value Ca[i%A] based on a remainder obtained by dividing the count code i of the time digital converter 41 by the Bin count A. Similarly, count values ​​Cb[i%B], Cc[i%C], and Cd[i%D] are stored in the storage sections 114 corresponding to ModB, ModC, and ModD.

[0371] The minimum search section 111 sorts the data of each interval according to the count value, and sorts the data into count signals C1, C2, C3 and C4 in descending order of the count value. The count signals C1 to C4 are respectively input to a plurality of ( Fig.26 In addition, weighting coefficients w1, w2, w3 and w4 for multiplying the count signals C1, C2, C3 and C4 are input to the weighting section 112. The storage section 113 stores the weighted count signals C1 to C4 in the weighting section 112.

[0372] In the case of adopting the above-mentioned LCP scheme, the weighting coefficients are set to, for example, w1=w2=w3=0 and w4=1. As a result, the count values ​​included in the count signals C1 to C3 are ignored, and a reconstructed histogram (for example, Fig.25BIt should be noted that the distance measuring unit 44b can generate a reconstructed histogram by adjusting the weighting coefficient to reflect the information of the count values ​​of the count signals C1 to C3. The scheme of generating a reconstructed histogram based on the count values ​​weighted according to the order of magnitude is also called an extended LCP scheme. Alternatively, the distance measuring unit 44b can omit the weighting unit 112 and directly input the count signal C4 extracted by the minimum search unit 111 to the storage unit 113.

[0373] As described above, in the seventh embodiment, when a peak value appears in the same interval of multiple replica histograms, a reconstructed histogram is generated based on the replica histogram with the minimum count value among the multiple replica histograms. Therefore, since a true peak value can be detected with a small count value, the circuit scale of the counter can be reduced, and the possibility of erroneously detecting a false peak value can be avoided. The LCP scheme described in the seventh embodiment can be applied to any one of the first to sixth embodiments.

[0374] (Eighth Embodiment)

[0375] The distance measuring system 1 of the present disclosure is based on the premise that the distance measuring process is performed by detecting the peak of the histogram generated by repeatedly receiving the reflected light emitted from a specific light emitting device and reflected by the object. However, it is possible to directly receive the light from an unknown light emitting body other than the specific light emitting device, or to receive the reflected light obtained by reflecting the illuminated object. Since the received light caused by the light from the unknown light emitting body is interference light and may adversely affect the distance measuring accuracy, it is necessary to suppress the influence of the interference light.

[0376] Fig. 27 1 is a diagram for explaining a method of suppressing the influence of disturbance light of the distance measuring system 1 according to the eighth embodiment. As described above, the distance measuring system 1 of the present disclosure measures the distance to the distance measuring target object based on the peak value of the histogram generated by repeatedly receiving the reflected light pulse signal having periodicity. Therefore, the disturbance light without periodicity does not generate a peak value and does not affect the distance measurement. In addition, even in the case where the disturbance light has periodicity, such as Fig. 27 As shown, when the lighting cycle of the distance measuring system 1 is different from the lighting cycle of the disturbance light, the count value component due to the disturbance light is scattered over the entire histogram. Therefore, the peak value due to the disturbance light becomes sufficiently smaller than the true peak value and thus does not affect the distance measurement.

[0377] Therefore, disturbance light having the same lighting cycle as that of the distance measuring system 1 of the present disclosure is assumed to be disturbance light that may affect distance measurement. More specifically, when there are two or more distance measuring systems 1 of the present disclosure, it is assumed that they affect each other. Fig. 27An embodiment is shown in which the ranging system 1 (System_1) according to the eighth embodiment of the present disclosure performs ranging in a light emission cycle different from the light emission cycle of another ranging system (System_2). More specifically, when System_2 performs ranging of ModB, System_1 performs ranging of ModA having a different Bin cycle from ModB. As a result, System_1 can suppress the influence of interference light received from System_2, and can also suppress the influence of interference light from System_1 to System2. It should be noted that in this specification, the Bin cycle may be referred to as MOD.

[0378] The distance measuring system 1 according to the eighth embodiment includes an interference suppression unit 120 for suppressing the influence of the above-mentioned interference light. For example, the interference suppression unit 120 is built in Figure 1 Alternatively, it may be provided separately from the control unit 22.

[0379] Fig.28 1 is a block diagram showing an interference suppression unit 120 according to an eighth embodiment. The interference suppression unit 120 includes an interference detection unit 121, a synchronization determination unit 122, and a period detection unit 123. The interference detection unit 121 detects the presence or absence of an unknown optical pulse signal (ie, Fig. 27 The interference detection unit 121 detects interference, and the synchronization determination unit 122 determines whether it is possible to synchronize with the period switching of the interference light. The period detection unit 123 detects the switching order of multiple periods of the interference light. The interference detection unit 121, the synchronization determination unit 122, and the period detection unit 123 cause the histogram generator 42 to generate a histogram for detecting interference light.

[0380] In addition, the disturbance detection section 121, the synchronization determination section 122, and the cycle detection section 123 cause the light emission timing control section 23 to control the light emission timing of the light emitting device 3 to avoid the influence of the disturbance light. Fig. 27 As described above, the light-emission timing control unit 23 causes the light-emitting device 3 to repeatedly emit light at a light-emission cycle different from the light-emission cycle of the interfering light (i.e., at a time interval different from the multiple time intervals of the interfering light). Alternatively, the light-emission timing control unit 23 causes the light-emitting device 3 to repeatedly emit light at a sequence different from the sequence of the multiple time intervals of the interfering light (i.e., the switching order of the cycles).

[0381] Fig.291 is a flowchart for implementing the interference light suppression method according to the eighth embodiment. First, before starting the distance measurement, the distance measurement system 1 according to the eighth embodiment is set to the listening mode (step S121). In the listening mode, the light emitting device 3 stops emitting light, and the light detection device 4 performs a light receiving process for detecting an unknown light pulse signal (i.e., interference light). In step S121, for example, Fig.28 The disturbance detection section 121 in the control unit 23 causes the light emission timing control section 23 to stop the light emission of the light emitting device 3, and causes the distance measurement control section 26 to monitor the presence or absence of disturbance light.

[0382] The interference detection unit 121 determines the presence or absence of interference light (step S122). Here, interference light is light received periodically as described above, and light received without periodicity is not considered as interference light. In the case where no interference light is detected, the ranging system 1 is set to normal ranging mode (step S123). Specifically, the light emitting device 3 starts to emit light, and the light detection device 4 performs normal multi-frequency ranging. Normal multi-frequency ranging is ranging according to any one of the first to seventh embodiments.

[0383] In the case where interfering light is detected in step S122, synchronization pull-in is performed (step S124). Synchronization pull-in is a process of specifying the period of the interfering light. The synchronization determination unit 122 attempts to synchronize the period of the specific MOD of the ranging system 1 with any period of the interfering light. If any period of the interfering light is the same as the period of the specific MOD of the ranging system 1, synchronization can be performed by aligning the phase of the interfering light. The synchronization determination unit 122 determines whether the synchronization pull-in is successful (step S125).

[0384] In the case where the synchronous introduction is successful in step S125, the interference light is further analyzed based on this. In the case where the interference light switches multiple cycles in sequence, the cycle detection unit 123 detects the switching order (step S126). This process is performed to detect whether the interference light is performing ranging by switching multiple cycles in a switching order similar to the switching order of the ranging system according to the present disclosure. Since the switching order of the MOD of the other device (hereinafter, MOD order) is detected, this process is also called other device MOD order detection mode.

[0385] In the other device MOD order detection mode, the interference suppression unit 120 detects the MOD order of other devices by confirming the degree of interference while changing the MOD order of the ranging system 1. First, based on the MOD order set in step S126, it is determined whether the cycle detection unit 123 has successfully detected the MOD order of other devices (step S127).

[0386] When the cycle detection unit 123 successfully detects the MOD sequence of other devices, the interference suppression unit 120 changes the MOD sequence of the distance measurement system 1 based on the MOD sequence of other devices (step S128). Here, the MOD sequence of the distance measurement system 1 is changed so as to be different from the MOD sequence of other devices. The influence of interference light can be avoided by making the MOD sequence of the distance measurement system 1 different from the MOD sequence of other devices.

[0387] The distance measurement mode in step S128 is also called other device synchronization MOD sequential change distance measurement mode.

[0388] In the case where the cycle detection section 123 fails to detect the MOD sequence of other devices in step S127, the interference suppression section 120 determines whether the MOD sequence of other devices has been detected in all MOD sequences (step S129). In the case where there is a MOD sequence in which the MOD sequence of other devices has not been detected, the interference suppression section 120 changes the MOD sequence of the ranging system 1 to the MOD sequence in which the MOD sequence of other devices has not been detected (step S130). As a result, the cycle detection section 123 detects the MOD sequence of other devices again, and the determination in step S127 is performed.

[0389] Repeat steps S127 to S130 until the detection in the MOD sequence of other devices in all MODs succeeds or the detection in the MOD sequence of other devices fails. In the case where it is determined in step S129 that the detection in the MOD sequence of other devices has been performed in all MOD sequences, it is considered that the specification of the MOD sequence of other devices has failed.

[0390] In the case where the synchronization pull-in fails in step S125 or the specification of the MOD order of the other device fails, the synchronization determination unit 122 determines that synchronization with the other device is impossible. Therefore, the ranging system 1 performs ranging in the interference suppression ranging mode. Specifically, the ranging system 1 performs ranging by randomizing the MOD order and the MOD switching interval, thereby reducing interference with ranging from other devices.

[0391] Fig. 30A and 30B It is used to illustrate Fig.29 A simplified diagram of the details of the listening mode performed in step S121. Fig. 30C It is used to illustrate Fig.29 A simplified diagram of the details of the synchronous pull-in performed in step S124. FIG. 30A to FIG. 30CThe period switching timing between the periods of the ranging system 1 (System_1) and another ranging system (System_2) according to the eighth embodiment of the present disclosure is shown. System_1 and System_2 perform ranging while switching between ModA, ModB, and ModC having different Bin periods (i.e., different PRIs). It is assumed that ModA, ModB, and ModC have long Bin periods (and PRIs) in this order. Note that in this specification, a series of ranging periods including each of ModA to ModC is also referred to as a MOD period.

[0392] Furthermore, in System_1 (and System_2), the MOD period (exposure period) Rem from ModA to ModC is the same. As a result, in the synchronization pull-in described later, the MOD switching timing can be synchronized between System_1 and System_2. Note that since one PRI is shorter in ModC than in ModA, the number of PRIs increases. The influence of the difference in the number of PRIs can be corrected by, for example, weighting the count value, etc.

[0393] exist Fig. 30A In step S121, before starting the distance measurement, System_1 is set to the listening mode. In the listening mode, when the light emission of the light emitting device 3 stops, System_1 uses any one of the plurality of Bin cycles to detect the interference light. In the listening mode, a histogram is generated by repeatedly using any one of the MOD cycles. Fig. 30A In the embodiment of , System_1 detects interference light, wherein ModAa, ModAb and ModAc have the same Bin period as ModA. ModAa, ModAb and ModAc accumulate count values ​​independently and generate histograms independently. Fig. 30A In ModAa to ModAc, a histogram is generated based on the interference light from System_2.

[0394] In the monitoring mode, System_1 can detect interfering light in the same Bin cycle as ModB or ModC instead of ModA. Note that in order to reduce exposure waste and synchronization error, the Bin cycle with the longest Bin cycle and a small amount of PRI (i.e., in Fig. 30A It is effective to perform the interference light detection operation in the Bin cycle of ModA).

[0395] like Fig. 30AAs shown in , during the period when System_2 emits light of ModA, System_1 and System_2 have the same Bin period and receive interference (hereinafter, other device interference period). Fig. 30A In the embodiment of , the period RAb in ModAb and the period RAc in ModAc are other-device interference periods. There is no other-device interference period in ModAa.

[0396] The sum of the periods RAb and RAc matches the exposure period Rem of ModA of System_2. The MOD switching period of System_1 differs from the MOD switching period of System_2 by an interval Dem. How much of the exposure period Rem is allocated to the period RAb (optionally, the period RAc) varies depending on the length of the interval Dem. Note that the interval Dem is different from the interval Dem. Fig. 30A The periods RAc shown have the same length.

[0397] Fig. 30B : is a graph showing the peaks of the histogram generated in ModAa to ModAc. In ModAb and ModAc with the period of interference from other devices, the peaks PAb and PAc appear. In ModAa without the period of interference from other devices, no peak appears.

[0398] In listening mode, Fig.29 As shown in step S122 of , the presence or absence of interference light is detected based on whether the multiple histograms generated by the multiple MODs have a peak. In the case where no histogram has a peak in the multiple histograms generated in the listening mode, it is found that there is no other device interference period, that is, there is no interference light. In this case, Fig.29 As shown in step S123, the distance measuring system 1 is set to the normal distance measuring mode. In addition, in the case where one of the plurality of histograms has a peak, the presence of disturbance light can be detected.

[0399] exist Fig. 30B In FIG. 1 , the peaks PAb and PAc enable System_1 to detect the presence of interfering light having the same lighting period as the Bin period of ModA.

[0400] like Fig.29 As shown in step S124 in FIG. 1 , when interfering light is detected, System_1 Fig. 30B The histogram in is pulled in synchronously. System_1 detects the shift of the cycle switching timing from the disturbance light of multiple peaks generated in the listening mode, and synchronizes the cycle switching timing with the disturbance light based on the detected shift.

[0401] Fig. 30BThe peak values ​​PAb and PAc shown have count values ​​(hereinafter, peak count values) CnAb and CnAc corresponding to the lengths of other device interference periods RAb and RAc, respectively. System_1 can detect other device interference periods RAb and RAc based on the difference between the peak count values ​​CnAb and CnAc, and can detect the interval Dem as the shift of the period switching timing based on the interference light.

[0402] Fig. 30C is a diagram showing synchronous pull-in. Fig.29 As shown in step S125, in order to confirm whether the synchronization pull-in is successful, similar to the monitoring mode, System_1 detects interference light of multiple MOD cycles and generates multiple histograms. In the case of successful synchronization pull-in, only one of the multiple MOD cycles has an interference cycle of other devices, and only one of the multiple histograms has a peak. Fig. 30C In the embodiment of , among ModAa to ModAc, only ModAb has the other device interference period, and only ModAb has the peak value PA in the histogram. In addition, the peak value PA has a peak count value corresponding to the exposure period Rem.

[0403] In the case where two or more histograms among the plurality of histograms have peaks, the synchronous pull-in fails. In the case where the synchronous pull-in fails, System_1 performs ranging in the interference rejection ranging mode described later. Note that System_1 can determine whether the synchronous pull-in is successful based on whether the peak detected after the synchronous pull-in has a peak count value equal to or greater than a predetermined threshold corresponding to the exposure period Rem.

[0404] Fig.31A and 31B is used to explain Fig.29 FIG. 1 is a diagram of the other device MOD sequence detection mode shown in steps S126 and S127 of . System_1 detects disturbance light through ModA to ModC when the light emission of the light emitting device 3 stops. In addition, System_1 rearranges the sequence of ModA to ModC in a different manner and generates a histogram for each of ModA to ModC. When a specific MOD sequence rearranged by System_1 matches the MOD sequence of System_2, in the case corresponding to Fig.31A A peak is detected in any of the three histograms of each MOD cycle shown in . That is, in the case where a peak is detected in each of the three histograms, the MOD order of System_1 is the same as the MOD order of System_2. Therefore, in the other device MOD order detection mode, the MOD order of System_2 can be easily detected.

[0405] Fig.31B It is a diagram showing an example of a failure in another device MOD sequential detection mode. Fig.31B An embodiment in which System_1 and System_2 have different MOD orders is shown. More specifically, in ModA to ModC, the order of ModA is the same, but the orders of ModB and ModC are different. As a result, only ModA has the other device interference period, and the peak value appears in the histogram only in ModA. In the case that there is even one histogram without a peak value among the multiple histograms, System_1 changes the MOD order and detects interference light again and generates multiple histograms, such as Fig.29 As shown in step S130.

[0406] Note that System_1 can change the MOD order randomly, or can change the MOD order only for MODs where no peaks appear in the histogram (in Fig.31B In addition, System_1 can confirm that Fig. 30C The peak value of the synchronous pull-in is used to specify the order of ModA in advance. For example, in Fig. 30C In the example above, ModA can be designated as being in the position of ModAb.

[0407] System_1 repeats the change of MOD sequence and the detection of the peak value of the histogram in each MOD cycle. Fig.31A The other means shown in the MOD sequence detection success cannot be confirmed in all combinations of MOD sequences, such as in Fig.29 As shown in step S129 of , System_1 determines that the other device MOD sequence detection has failed. In this case, System_1 performs ranging in the interference rejection ranging mode.

[0408] As described above, by using the histogram generated by the histogram generator 42 in a state where the light emitting device 3 does not emit light, the distance measuring system 1 can detect the presence or absence of interference light, perform synchronous pull-in, and detect the MOD order of other devices.

[0409] Fig.32 It is shown in Fig.29 Another device synchronization MOD sequentially changes the ranging mode as shown in step S128. Fig.31A When the MOD sequence of System_2 is detected by the MOD sequence detection mode of the other device as shown in FIG. 1 , System_1 shifts the MOD sequence of System_2 and applies it to the MOD sequence of System_2. Fig.32 Specifically, Fig.32As shown in , System_1 causes the light emitting device 3 to emit light using a MOD sequence in which the MOD sequence of System_2 is shifted by one MOD cycle.

[0410] Note that, in the case where a MOD sequence having no peak value among all of ModA to ModC (i.e., a MOD sequence different from the MOD sequence of other devices) is detected in the other device MOD sequence detection mode, System_1 can cause the light emitting device 3 to emit light using the MOD sequence. As described above, the ranging system 1 performs multi-frequency ranging in a MOD sequence obtained by time-shifting the MOD sequence of other devices detected by the period detection unit 123 or in a MOD sequence different from the detected MOD sequence of other devices.

[0411] Fig.33 is a diagram showing the interference rejection ranging mode ( Fig.29 In the case of synchronous pull-in or other device MOD sequence detection failure, if multiple MOD cycles in System_1 are used as is, there is a possibility that the interference will have a significant impact on System_2.

[0412] In this case, System_1 randomly performs ranging without fixing the MOD order and MOD period. As a result, System_1 finely disperses the other device interference period and mitigates other device interference. Fig.33 In the embodiment of the present invention, System_1 has a MOD cycle from ModA1 to ModA1 randomized by ModA, and a MOD cycle from ModB1 to ModB1 randomized by ModB. m And the MOD cycle is randomized by ModC1 to ModC n Randomly switch between ModA1 and ModA1, ModB1 and ModB m and ModC1 to ModC n with randomized numbers of exposure periods and PRIs, respectively.

[0413] Note that in the interference mitigation ranging mode, the total number of PRIs is set to be the same so that there is no difference in the total number of light reception frequencies of the histograms generated by ModA to ModC. Specifically, the sum of the number of PRIs of ModA1 to ModA1, ModB1 to ModB m The sum of the PRI quantities of ModC1 to ModC n The sum of the PRI quantities is adjusted to be the same.

[0414] In the interference reduction ranging mode, the emission timing control unit 23 controls the emission timing of the light emitting device 3 to reduce interference with interference light. As described above, the light emitting device 3 randomizes the emission cycles of the plurality of light pulse signals so that the total number of light pulse signals used to generate the plurality of histograms becomes equal.

[0415] Similar to System_1, the interference suppression ranging mode can mitigate interference to the ranging of System_1 for any of System_2a that performs multi-frequency ranging in a random MOD order and at a MOD switching interval, System_2b that performs multi-frequency ranging in a uniform Mod order and at a Mod switching interval, and System_2c that performs normal ranging in a single Bin cycle X.

[0416] As described above, in the ranging system 1 according to the eighth embodiment of the present disclosure, first, interference light is repeatedly received in a state set to a specific MOD cycle, and it is detected whether the interference light has a specific MOD cycle. In the case where the interference light has a specific MOD cycle, synchronous pull-in is performed, and then the switching order of multiple MOD cycles in the interference light is detected. When the switching order of multiple MOD cycles in the interference light can be detected, the MOD cycle is switched to a MOD cycle different from the interference light, and a ranging process similar to the first to seventh embodiments is performed. Therefore, similar to the ranging system according to the contents of the present disclosure, even in an environment where interference light for switching multiple MOD cycles is received, a highly accurate ranging process can be performed without being affected by the interference light.

[0417] (Application example)

[0418] The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure can also be implemented as a device installed on any kind of mobile body (such as, automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility, airplanes, drones, ships, robots, construction machines, agricultural machines (tractors), etc.).

[0419] Fig.34 7000 is a block diagram showing an example of a schematic configuration of a vehicle control system 7000 as an example of a mobile body control system to which the technology according to an embodiment of the present disclosure can be applied. The vehicle control system 7000 includes a plurality of electronic control units connected to each other via a communication network 7010. Fig.34In the illustrated embodiment, the vehicle control system 7000 includes a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an external information detection unit 7400, an internal information detection unit 7500, and an integrated control unit 7600. For example, the communication network 7010 connecting the plurality of control units to each other may be an in-vehicle communication network conforming to any standard, such as a controller area network (CAN), a local interconnect network (LIN), a local area network (LAN), FlexRay (registered trademark), and the like.

[0420] Each control unit includes: a microcomputer that performs calculations according to various programs; a storage unit that stores programs executed by the microcomputer, parameters for various operations, etc.; and a drive circuit that drives various control object devices. Each control unit also includes: a network interface (I / F) for communicating with other control units via the communication network 7010; and a communication I / F for communicating with devices, sensors, etc. inside and outside the vehicle through wired communication or radio communication. Fig.34 The functional configuration of the integrated control unit 7600 shown includes a microcomputer 7610, a general communication I / F 7620, a dedicated communication I / F 7630, a positioning section 7640, a beacon receiving section 7650, an in-vehicle device I / F 7660, a sound / image output section 7670, an in-vehicle network I / F 7680, and a storage section 7690. Other control units similarly include a microcomputer, a communication I / F, a storage section, and the like.

[0421] The drive system control unit 7100 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 7100 is used as a control device for a drive force generating device (such as an internal combustion engine, a drive motor, etc.) for generating the drive force of the vehicle, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, a braking device for generating the braking force of the vehicle, etc. The drive system control unit 7100 may have a function as a control device for an anti-lock braking system (ABS), an electronic stability control (ESC), etc.

[0422] The drive system control unit 7100 is connected to the vehicle state detection unit 7110. The vehicle state detection unit 7110 includes, for example, a gyro sensor for detecting the angular velocity of the axial rotational motion of the vehicle body, an acceleration sensor for detecting the acceleration of the vehicle, and at least one of sensors for detecting the amount of operation of the accelerator pedal, the amount of operation of the brake pedal, the steering angle of the steering wheel, the engine speed, or the speed of the wheels. The drive system control unit 7100 performs calculation processing using the signal input from the vehicle state detection unit 7110 to control the internal combustion engine, the drive motor, the electric power steering device, the brake device, and the like.

[0423] The body system control unit 7200 controls the operation of various devices provided in the body according to various programs. For example, the body system control unit 7200 is used as a control device for a keyless entry system, a smart key system, a power window device, or various lights such as a headlight, a backup light, a brake light, a turn signal, a fog light, etc. In this case, a radio wave emitted from a mobile device may be input to the body system control unit 7200 as a substitute for a signal of a key or various switches. The body system control unit 7200 receives these input radio waves or signals and controls the door lock device, the power window device, the lights, etc. of the vehicle.

[0424] The battery control unit 7300 controls the secondary battery 7310 as a power source for driving the motor according to various programs. For example, information about the battery temperature, the battery output voltage, the amount of charge remaining in the battery, etc. is supplied to the battery control unit 7300 from the battery device including the secondary battery 7310. The battery control unit 7300 performs arithmetic operation processing using these signals, and performs control for adjusting the temperature of the secondary battery 7310 or controlling a cooling device provided to the battery device, etc.

[0425] The vehicle exterior information detection unit 7400 detects information outside the vehicle including the vehicle control system 7000. For example, the vehicle exterior information detection unit 7400 is connected to at least one of the imaging unit 7410 and the vehicle exterior information detection unit 7420. The imaging unit 7410 includes at least one of a time of flight (ToF) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. For example, the vehicle exterior information detection unit 7420 includes at least one of an environmental sensor for detecting current atmospheric conditions or weather conditions and a peripheral information detection sensor for detecting other vehicles, obstacles, pedestrians, etc., outside the vehicle including the vehicle control system 7000.

[0426] For example, the environmental sensor may be at least one of a raindrop sensor for detecting rain, a fog sensor for detecting fog, a sunlight sensor for detecting the degree of sunlight, and a snow sensor for detecting snowfall. The peripheral information detection sensor may be at least one of an ultrasonic sensor, a radar device, and a LIDAR device (a light detection and ranging device, or a laser imaging detection and ranging device). Each of the imaging portion 7410 and the vehicle exterior information detection unit 7420 may be provided as an independent sensor or device, or may be provided as a device in which a plurality of sensors or devices are integrated.

[0427] Fig.35An example of the installation position of the imaging unit 7410 and the vehicle exterior information detection unit 7420 is shown. The imaging units 7910, 7912, 7914, 7916 and 7918 are, for example, installed at least one of the positions on the front nose, side mirrors, rear bumper and rear door of the vehicle 7900 and the position on the upper part of the windshield in the vehicle interior. The imaging unit 7910 installed at the front nose of the vehicle interior and the imaging unit 7918 installed at the upper part of the windshield mainly obtain the image in front of the vehicle 7900. The imaging units 7912 and 7914 installed at the side mirrors mainly obtain the image of the side of the vehicle 7900. The imaging unit 7916 installed at the rear bumper or rear door mainly obtains the image of the rear of the vehicle 7900. The imaging unit 7918 installed at the upper part of the windshield in the vehicle interior is mainly used to detect the front vehicle, pedestrians, obstacles, signals, traffic signs, lanes, etc.

[0428] By the way, Fig.35 An embodiment of the shooting range of each imaging unit 7910, 7912, 7914 and 7916 is shown. Imaging range a represents the imaging range of the imaging unit 7910 set to the front nose. Imaging ranges b and c respectively represent the imaging ranges of the imaging units 7912 and 7914 provided to the side mirrors. Imaging range d represents the imaging range of the imaging unit 7916 set to the rear bumper or the rear door. For example, by accumulating image data imaged by the imaging units 7910, 7912, 7914 and 7916, a bird's-eye view image of the vehicle 7900 viewed from above can be obtained.

[0429] The vehicle exterior information detection units 7920, 7922, 7924, 7926, 7928, 7930 provided at the front, rear, side, corners, and upper portion of the windshield inside the vehicle 7900 may also be, for example, ultrasonic sensors or radar devices. The vehicle exterior information detection units 7920, 7926, 7930 provided at the front nose, rear bumper, rear door of the vehicle 7900, and upper portion of the windshield inside the vehicle may also be, for example, LIDAR devices. These vehicle exterior information detection units 7920 to 7930 are mainly used to detect preceding vehicles, pedestrians, obstacles, and the like.

[0430] return Fig.34, will continue to describe. The vehicle exterior information detection unit 7400 enables the imaging unit 7410 to capture images outside the vehicle and receive captured image data. In addition, the vehicle exterior information detection unit 7400 receives detection information from the vehicle exterior information detection unit 7420 connected to the vehicle exterior information detection unit 7400. In the case where the vehicle exterior information detection unit 7420 is an ultrasonic sensor, a radar device, or a LIDAR device, the vehicle exterior information detection unit 7400 sends ultrasonic waves, electromagnetic waves, etc., and receives information of received reflected waves. Based on the received information, the vehicle exterior information detection unit 7400 can perform processing for detecting objects such as humans, vehicles, obstacles, signs, and text on the road surface, or processing for detecting the distance between the objects. In addition, the vehicle exterior information detection unit 7400 can also perform environmental recognition processing for identifying rainfall, fog, road conditions, etc. based on the received information. The vehicle exterior information detection unit 7400 can calculate the distance to an object outside the vehicle based on the received information.

[0431] In addition, the vehicle exterior information detection unit 7400 can perform image recognition processing to identify humans, vehicles, obstacles, signs, text on the road surface, etc., or detect the distance thereto based on the received image data. The vehicle exterior information detection unit 7400 can perform processing such as distortion correction, alignment, etc. on the received image data, and combine the image data imaged by multiple different imaging units 7410 to generate a bird's-eye view image or a panoramic image. The vehicle exterior information detection unit 7400 can perform viewpoint conversion processing using the image data captured by the imaging unit 7410, which includes different imaging components.

[0432] The in-vehicle information detection unit 7500 detects information about the interior of the vehicle. For example, the in-vehicle information detection unit 7500 is connected to a driver state detection unit 7510 that detects the state of the driver. The driver state detection unit 7510 may include a camera that images the driver, a biosensor that detects the driver's biometric information, a microphone that collects sounds inside the vehicle, and the like. The biosensor is, for example, arranged in a seat surface, a steering wheel, and the like, and detects biometric information of a passenger sitting on the seat or a driver holding the steering wheel. Based on the detection information input from the driver state detection unit 7510, the in-vehicle information detection unit 7500 can calculate the driver's fatigue or the driver's concentration, or can determine whether the driver is dozing off. The in-vehicle information detection unit 7500 may subject the audio signal obtained by collecting the sound to processing such as noise elimination processing.

[0433] The integrated control unit 7600 controls the general operation within the vehicle control system 7000 according to various programs. The integrated control unit 7600 is connected to the input unit 7800. The input unit 7800 is implemented by a device such as a touch panel, a button, a microphone, a switch, a lever, etc. that can be input by the occupant. The integrated control unit 7600 can be supplied with data obtained by voice recognition of the voice input through the microphone. The input unit 7800 can be, for example, a remote control device using infrared or other radio waves, or an external connection device that supports the operation of the vehicle control system 7000, such as a mobile phone, a personal digital assistant (PDA), etc. The input unit 7800 can be, for example, a camera. In this case, the occupant can input information through gestures. Alternatively, data obtained by detecting the movement of a wearable device worn by the occupant can be input. In addition, the input unit 7800 can include, for example, an input control circuit, etc., which generates an input signal based on the information input by the occupant, etc. using the above-mentioned input unit 7800, and outputs the generated input signal to the integrated control unit 7600. The occupants and the like input various data or instruct processing operations to the vehicle control system 7000 by operating the input unit 7800 .

[0434] The storage unit 7690 may include a read-only memory (ROM) storing various programs executed by the microcomputer and a random access memory (RAM) storing various parameters, operation results, sensor values, etc. In addition, the storage unit 7690 may be implemented by a magnetic storage device such as a hard disk drive (HDD), a semiconductor storage device, an optical storage device, a magneto-optical storage device, etc.

[0435] The general communication I / F 7620 is a widely used communication I / F that mediates communication with various devices existing in the external environment 7750. The general communication I / F 7620 can implement a cellular communication protocol such as Global System for Mobile Communications (GSM (registered trademark)), Worldwide Interoperability for Microwave Access (WiMAX (registered trademark)), Long Term Evolution (LTE (registered trademark)), LTE-Advanced (LTE-A), etc., or another wireless communication protocol such as a wireless LAN (also known as Wireless Fidelity (Wi-Fi (registered trademark)), Bluetooth (registered trademark), etc. For example, the general communication I / F 7620 can be connected to a device (e.g., an application server or a control server) existing on an external network (e.g., the Internet, a cloud network, or a company-specific network) via a base station or an access point. In addition, for example, the general communication I / F 7620 can be connected to a terminal existing near the vehicle (the terminal is, for example, a driver's terminal, a pedestrian or a store, or a machine type communication (MTC) terminal) using a peer-to-peer (P2P) technology.

[0436] The dedicated communication I / F 7630 is a communication I / F that supports the development of a communication protocol for use in a vehicle. The dedicated communication I / F 7630 may implement a standard protocol such as Wireless Access in Vehicular Environments (WAVE) (which is a combination of Institute of Electrical and Electronics Engineers (IEEE) 802.11p as a lower layer and IEEE 1609 as a higher layer), Dedicated Short Range Communication (DSRC), or a cellular communication protocol. The dedicated communication I / F 7630 generally performs V2X communication as a concept including one or more of the following: communication between vehicles and vehicles (vehicle to vehicle), communication between roads and vehicles (vehicle to infrastructure), communication between vehicles and homes (vehicle to home), and communication between pedestrians and vehicles (vehicle to pedestrians).

[0437] The positioning unit 7640 performs positioning, for example, by receiving a global navigation satellite system (GNSS) signal (e.g., a GPS signal from a global positioning system (GPS) satellite) from a GNSS satellite, and generates position information including the latitude, longitude, and altitude of the vehicle. Incidentally, the positioning unit 7640 may identify the current position by exchanging signals with a wireless access point, or may obtain position information from a terminal such as a mobile phone, a personal handyphone system (PHS), or a smart phone having a positioning function.

[0438] For example, the beacon receiving unit 7650 receives radio waves or electromagnetic waves emitted from a radio station installed on a road or the like, and thereby obtains information on the current position, congestion, closed roads, necessary time, etc. Incidentally, the function of the beacon receiving unit 7650 may be included in the above-mentioned dedicated communication I / F 7630.

[0439] The in-vehicle device I / F 7660 is a communication interface for mediating the connection between the microcomputer 7610 and various in-vehicle devices 7760 present in the vehicle. The in-vehicle device I / F 7660 can establish a wireless connection using a wireless communication protocol such as wireless LAN, Bluetooth (registered trademark), near field communication (NFC), or wireless universal serial bus (WUSB). In addition, the in-vehicle device I / F 7660 can establish a wired connection through a universal serial bus (USB), a high-definition multimedia interface (HDMI (registered trademark)), a mobile high-definition link (MHL), etc. via a connection terminal (and a cable, if necessary) not shown in the figure. The in-vehicle device 7760 may, for example, include at least one of a mobile device and a wearable device owned by an occupant and an information device carried or attached to the vehicle. The in-vehicle device 7760 may also include a navigation device that searches for a path to an arbitrary destination. The in-vehicle device I / F 7660 exchanges control signals or data signals with these in-vehicle devices 7760.

[0440] The in-vehicle network I / F 7680 is an interface that mediates communication between the microcomputer 7610 and the communication network 7010. The in-vehicle network I / F 7680 transmits and receives signals and the like according to a predetermined protocol supported by the communication network 7010.

[0441] The microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 according to various programs based on information obtained via at least one of the general communication I / F 7620, the dedicated communication I / F 7630, the positioning unit 7640, the beacon receiving unit 7650, the in-vehicle device I / F 7660, and the vehicle network I / F 7680. For example, the microcomputer 7610 can calculate the control target value of the driving force generation device, the steering mechanism, or the braking device based on the information obtained about the inside and outside of the vehicle, and output a control command to the drive system control unit 7100. For example, the microcomputer 7610 can perform cooperative control aimed at realizing the functions of the advanced driver assistance system (ADAS), which includes collision prevention or shock absorption for the vehicle, follow-up driving based on the following distance, vehicle speed maintenance driving, warning of vehicle collision, warning of vehicle deviation from the lane, etc. In addition, microcomputer 7610 can perform cooperative control intended for autonomous driving by controlling a drive force generating device, a steering mechanism, a braking device, etc. based on information obtained about the vehicle's surroundings, thereby enabling the vehicle to travel automatically without depending on the driver's operation, etc.

[0442] The microcomputer 7610 may generate three-dimensional distance information between the vehicle and objects such as surrounding structures, people, etc., based on information obtained via at least one of the general communication I / F 7620, the dedicated communication I / F 7630, the positioning unit 7640, the beacon receiving unit 7650, the in-vehicle device I / F 7660, and the vehicle network I / F 7680, and generate local map information including information about the surroundings of the current position of the vehicle. In addition, the microcomputer 7610 may predict dangers such as collision of the vehicle, approach of pedestrians, etc., entering a closed road, etc., based on the obtained information, and generate a warning signal. The warning signal may be, for example, a signal for generating a warning sound or lighting a warning light.

[0443] The sound / image output unit 7670 sends an output signal of at least one of sound and image to an output device, which can visually or auditorily notify the occupants of the vehicle or the outside of the vehicle of information. Fig.34In the embodiment of the invention, the audio speaker 7710, the display unit 7720 and the instrument panel 7730 are shown as output devices. For example, the display unit 7720 may include at least one of an onboard display and a head-up display. The display unit 7720 may have an augmented reality (AR) display function. The output device may be different from these devices, and may be another device such as headphones, a wearable device such as a glasses-type display worn by a passenger, a projector, a lamp, etc. In the case where the output device is a display device, the display device visually displays the results obtained by various processes performed by the microcomputer 7610 or information received from another control unit in various forms such as text, images, tables, graphics, etc. In addition, in the case where the output device is an audio output device, the audio output device converts an audio signal composed of reproduced audio data or sound data, etc. into an analog signal, and outputs the analog signal audibly.

[0444] By the way, in Fig.34 In the embodiment depicted in, at least two control units connected to each other via the communication network 7010 can be integrated into one control unit. Alternatively, each individual control unit may include multiple control units. In addition, the vehicle control system 7000 may include another control unit not shown in the figure. In addition, part or all of the functions performed by one of the control units described above can be assigned to another control unit. That is, as long as information is sent and received via the communication network 7010, predetermined arithmetic processing can be performed by any control unit. Similarly, a sensor or device connected to one of the control units can be connected to another control unit, and multiple control units can send and receive detection information to each other via the communication network 7010.

[0445] It should be noted that a computer program for realizing each function of the distance measuring unit 44 according to the present embodiment can be implemented on any control unit or the like. In addition, a computer readable recording medium in which such a computer program is stored can be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, etc. In addition, the above-mentioned computer program can be distributed via, for example, a network without using a recording medium.

[0446] Also, see Figure 1 At least some of the components of the ranging system 1 described in the example above may be used in a Fig.34 The integrated control unit 7600 shown in FIG. 76 is implemented in a module (eg, an integrated circuit module including one die).

[0447] It should be noted that the present technology can have the following configurations.

[0448] (1) A light detection device comprising:

[0449] a light receiving section that receives a first reflected light pulse signal within a first time range, in which a first light pulse signal emitted at a first time interval is reflected by an object, and a second reflected light pulse signal within a second time range different from the first time range, in which a second light pulse signal emitted at a second time interval different from the first time interval is reflected by the object; and

[0450] A histogram generator, the histogram generator generates a first histogram and a second histogram, in which the light receiving frequency of the first reflected light pulse signal received within the first time range is classified for each predetermined fixed unit period, and in the second histogram, the light receiving frequency of the second reflected light pulse signal received within the second time range is classified for each unit period.

[0451] (2) The light detection device according to (1), further comprising:

[0452] A copy histogram generator generates a first copy histogram obtained by copying the first histogram by a first number corresponding to the first time interval, and generates a second copy histogram obtained by copying the second histogram by a second number corresponding to the second time interval.

[0453] (3) The light detection device according to (2),

[0454] wherein the light receiving unit receives two or more reflected light pulse signals within two or more different time ranges, wherein among the two or more reflected light pulse signals, two or more light pulse signals emitted at two or more time intervals including a first time interval and a second time interval different from each other are reflected by the object,

[0455] a histogram generator generating two or more histograms obtained by classifying the light reception frequencies of two or more reflected light pulse signals received within two or more time ranges for each unit period,

[0456] The replicated histogram generator generates two or more replicated histograms, wherein the two or more replicated histograms are obtained by replicating each of the two or more histograms by a number corresponding to the corresponding time interval.

[0457] The two or more histograms generated by the histogram generator include a first histogram and a second histogram, and

[0458] The two or more replica histograms generated by the replica histogram generator include a first replica histogram and a second replica histogram.

[0459] (4) The light detection device according to (3),

[0460] wherein the light receiving unit includes a plurality of pixels arranged in two or more in each of the first direction and the second direction, and

[0461] Each of the plurality of pixels receives more than two reflected light pulse signals within more than two time ranges.

[0462] (5) The light detection device according to (4), further comprising:

[0463] A packet generator generates ranging data including more than two histograms in units of frames,

[0464] The ranging data includes a start part, a plurality of groups and an end part.

[0465] The beginning portion includes a header indicating a frame and an identifier indicating the number of two or more time intervals,

[0466] The packet includes a header, histogram data, and a footer, the header including a corresponding histogram interval count and a number of pixels in two or more histograms, the histogram data forming a corresponding histogram, the footer including end information of the corresponding histogram, and

[0467] The end portion includes an identifier indicating the end of the frame.

[0468] (6) The light detection device according to (4), further comprising:

[0469] A packet generator generates ranging data including more than two histograms in units of frames,

[0470] The ranging data includes a start part, a plurality of groups and an end part.

[0471] The start portion includes an identifier indicating a header of a frame, a number of a plurality of pixels, and a number of two or more time intervals,

[0472] The packet includes a header, histogram data, and a trailer, the header including information indicating a pixel position, the histogram data constituting a corresponding histogram among two or more histograms, the trailer including end information of the corresponding histogram, and

[0473] The end portion includes an identifier indicating the end of the frame.

[0474] (7) The light detection device according to any one of (4) to (6), further comprising:

[0475] A distance measuring unit measures the distance of an object based on a light reception time when light reception times corresponding to peak positions of two or more replica histograms including a first replica histogram and a second replica histogram match each other, or a light reception time corresponding to a maximum peak position of a reconstructed histogram synthesized by aligning interval counts of two or more replica histograms.

[0476] (8) The light detection device according to (7),

[0477] The distance measuring unit adds two or more replica histograms for each interval to generate a reconstructed histogram.

[0478] (9) The light detection device according to (7),

[0479] where each of the two or more replicate histograms has the same bin counts, and

[0480] The distance measuring section searches for the same interval in which each of the two or more replica histograms has a peak value of the light reception frequency, and generates a reconstructed histogram based on a minimum peak value in the searched intervals.

[0481] (10) The light detection device according to any one of (4) to (9), further comprising:

[0482] a plurality of time-to-digital converters and a plurality of histogram generators arranged for each first pixel group including two or more pixels arranged in a first direction,

[0483] wherein each of the plurality of time-to-digital converters sequentially generates a digital signal according to the reception time of two or more reflected light pulse signals received by each pixel in the corresponding first pixel group, and

[0484] Each of the plurality of histogram generators generates two or more histograms based on digital signals sequentially generated by the corresponding time-to-digital converter.

[0485] (11) The light detection device according to (10),

[0486] wherein a plurality of second pixel groups each including two or more pixels arranged in the second direction are arranged in the first direction, and

[0487] A plurality of second pixel groups are sequentially selected, and each pixel in the selected second pixel group inputs light reception signals corresponding to two or more reflected light pulse signals to a plurality of time-to-digital converters in parallel.

[0488] (12) The light detection device according to (11),

[0489] Each pixel in the selected second pixel group sequentially outputs more than two light receiving signals according to more than two reflected light pulse signals within one frame period, and the light receiving signals output by corresponding pixels in the second pixel group are input to multiple time-to-digital converters in parallel.

[0490] (13) The light detection device according to any one of (4) to (9), further comprising:

[0491] multiple time-to-digital converters and multiple histogram generators arranged for each pixel,

[0492] wherein each of the plurality of time-to-digital converters generates a digital signal corresponding to a reception time of two or more reflected light pulse signals received by a corresponding pixel, and

[0493] Each of the plurality of histogram generators generates two or more histograms based on the digital signal generated by the corresponding time-to-digital converter.

[0494] (14) The light detection device according to (13),

[0495] Each of the plurality of pixels sequentially outputs two or more light receiving signals according to two or more reflected light pulse signals within one frame period, and the light receiving signal outputs of the corresponding pixels are input to a plurality of time-to-digital converters in parallel.

[0496] (15) The light detection device according to any one of (10) to (14),

[0497] The time-to-digital converter outputs a Gray code corresponding to the light reception time, and

[0498] The histogram generator includes a conversion table for converting the Gray code into light reception time data.

[0499] (16) The light detection device according to any one of (3) to (15), further comprising:

[0500] The storage unit stores two or more replicated histograms having bin counts corresponding to the least common multiple of the two or more time intervals.

[0501] (17) The light detection device according to any one of (3) to (15), further comprising:

[0502] The storage unit has a storage capacity corresponding to a bin count of the histogram, wherein the bin count corresponds to a maximum time interval among the two or more time intervals.

[0503] (18) The light detection device according to (17), further comprising:

[0504] an interval expansion unit that stores the histogram corresponding to the maximum time interval as a unit in the storage unit, expands the histogram corresponding to two or more time intervals excluding the maximum time interval by one unit, and stores the histogram in the storage unit;

[0505] a peak detection section that, in a storage area of ​​the storage section including two or more histograms corresponding to two or more time intervals in each of the one cells, repeatedly detects a position where light reception times of peaks of the two or more histograms match each other for each of the plurality of one cells;

[0506] A maximum peak detection unit detects a maximum value of peaks from among a plurality of units;

[0507] a shifting unit that shifts the maximum value of the peak value to the center of the corresponding storage area; and

[0508] The centroid calculation unit performs centroid calculation in the storage area shifted by the shift unit.

[0509] (19) The light detection device according to any one of (3) to (18),

[0510] Wherein, the histogram generator generates more than two histograms based on more than two reflected light pulse signals repeatedly obtained when the light pulse signal is repeatedly caused to emit light at each of more than two time intervals, and the number of frequencies other than the peaks of the more than two histograms is flattened by periodically shifting the start time when the more than two histograms are generated.

[0511] (20) The light detection device according to any one of (7) to (9), further comprising:

[0512] The interference detection unit detects whether there is interference caused by unknown optical pulse signals.

[0513] When the interference detecting unit detects that there is no interference, the distance measuring unit measures the distance of the object based on the reconstructed histogram.

[0514] (21) The light detection device according to (20), further comprising:

[0515] a synchronization determination unit that determines whether synchronization with the cycle switching of the unknown optical pulse signal is possible when interference is detected by the interference detection unit,

[0516] When the synchronization determination unit determines that synchronization is possible, the histogram generator generates two or more histograms in synchronization with the unknown optical pulse signal.

[0517] (22) The light detection device according to (21), further comprising:

[0518] The cycle detection unit detects the switching order of the cycle of the unknown optical pulse signal.

[0519] The histogram generator generates two or more histograms in a switching order in which the switching order of the cycles detected by the cycle detection unit is time-shifted or in a switching order different from the switching order of the cycles detected by the cycle detection unit.

[0520] (23) The light detection device according to (21) or (22), further comprising:

[0521] The light emission timing control section controls the light emission timing of the optical pulse signal including the first optical pulse signal and the second optical pulse signal so as to reduce interference with the unknown optical pulse signal when the synchronization determination section determines that synchronization is impossible.

[0522] (24) The light detection device according to (23),

[0523] The light emission timing control section randomizes the light emission period for generating the two or more light pulse signals in each of the plurality of histograms included in each of the two or more replica histograms.

[0524] (25) The light detection device according to (24),

[0525] The light emission timing control unit randomizes the light emission periods of the two or more light pulse signals so that the total number of light pulse signals used to generate the plurality of histograms is equal for each of the two or more replica histograms.

[0526] (26) A distance measuring system comprising:

[0527] Light emitting device; and

[0528] The light detection device according to any one of (3) to (25),

[0529] Wherein, the light emitting device comprises:

[0530] A first light emitting unit emits a plurality of first light pulse signals at first time intervals; and

[0531] The second light emitting unit emits a plurality of second light pulse signals at a second time interval, and

[0532] The optical detection device includes a light emission timing control unit, which controls the first light emission unit and the second light emission unit so that after the first light emission unit emits a number of first light pulse signals corresponding to a first time range at a first time interval, the first light emission unit emits a number of second light pulse signals corresponding to a second time range at a second time interval.

[0533] (27) According to the ranging system of (26),

[0534] The light emitting device emits each of the two or more light pulse signals at two or more time intervals, the number of which corresponds to the corresponding time range, and

[0535] The light emission timing control section performs control to sequentially emit two or more light pulse signals.

[0536] (28) The ranging system according to (26) or (27),

[0537] The optical detection device includes an interference detection unit for detecting an unknown optical pulse signal, and

[0538] The light emission timing control unit causes the light emitting device to emit light in a sequence different from the sequence of two or more time intervals at which the unknown light pulse signal detected by the interference detection unit is emitted, or repeatedly at time intervals different from the two or more time intervals.

[0539] (29) According to the ranging system of (28),

[0540] Wherein, when the light emitting device is not emitting light, the histogram generator generates two or more histograms based on the unknown light pulse signal, and

[0541] The interference detection section detects the presence or absence of interference due to the unknown optical pulse signal based on the two or more histograms.

[0542] (30) A distance measurement system, comprising:

[0543] A light emitting device comprising:

[0544] a first light emitting unit that emits a plurality of first light pulse signals at first time intervals, and

[0545] A second light emitting unit emits a plurality of second light pulse signals at a second time interval;

[0546] a light receiving unit that receives a first reflected light pulse signal within a first time range in which the first light pulse signal is reflected by an object and receives a second reflected light pulse signal within a second time range different from the first time range in which a second light pulse signal emitted at a second time interval different from the first time interval is reflected by the object; and

[0547] a packet generator, generating distance measurement data having two or more histograms, wherein the two or more histograms include a first histogram generated based on the first reflected light pulse signal and a second histogram generated based on the second reflected light pulse signal in units of frames,

[0548] The ranging data includes a start part, a plurality of groups and an end part.

[0549] The start portion includes a header indicating a frame and an identifier of the number of two or more time intervals including a first time interval and a second time interval,

[0550] The packet includes a header, histogram data and a trailer, the header includes the interval count of the corresponding histogram among the two or more histograms, the histogram data constitutes the corresponding histogram, the trailer includes the end information of the corresponding histogram, and

[0551] The end portion includes an identifier indicating the end of the frame.

[0552] Aspects of the present disclosure are not limited to the above-mentioned embodiments, but include various modifications that can be thought of by those skilled in the art, and the effects of the present disclosure are not limited to the above-mentioned contents. That is, various additions, modifications, and partial deletions are possible without departing from the conceptual concept and spirit of the present disclosure obtained from the contents defined in the claims and their equivalents.

[0553] Reference Symbols List

[0554] 1 Ranging system

[0555] 2 Overall control unit

[0556] 3 Lighting device

[0557] 4. 4a. 4b. 4c. 4d. Light detection device

[0558] 5,5a AP

[0559] 11. First light-emitting unit

[0560] 12. Second light emitting unit

[0561] 21 Clock generation unit

[0562] 22 Control Department

[0563] 23. Lighting timing control unit

[0564] 24, 24a, 24b driving circuit

[0565] 25 Light receiving unit

[0566] 26 Distance measurement control unit

[0567] 27 Distance measurement processing unit

[0568] 28 Interface

[0569] 30 pixels

[0570] 41, 41a Time to Digital Converter

[0571] 42.42a Histogram Generator

[0572] 44, 44a, 44b, 77 distance measuring unit

[0573] 45 Copy the Histogram Generator

[0574] 50, 50a, 50b pixel array portion

[0575] 51 first pixel group

[0576] 52, 52a second pixel group

[0577] 61 signal line

[0578] 62 Column selection circuit

[0579] 63 Column selection lines

[0580] 64 Row selection circuit

[0581] 65 Row Select Line

[0582] 71 Interval Extension

[0583] 72 Peak detection unit

[0584] 73 Maximum peak detection unit

[0585] 74 Displacement

[0586] 75 Centroid Calculation Department

[0587] 76 Group Generation Unit

[0588] 80,90 ranging data

[0589] 81,91 start

[0590] Groups 82, 82a, 82b, 82c, 82d, 82e, 82f, 82g, 92

[0591] 83,93 End

[0592] 84,94 header

[0593] 85, 85a, 85b, 95 histogram data

[0594] 86,96 end of report

[0595] Histograms of 87, 97a, 97b, 97c, 97d

[0596] 88 Filling

[0597] 101 Gray code counter

[0598] 102 Latch unit

[0599] 103 GT Conversion Department

[0600] 104 interval counter

[0601] 105 Photoelectric conversion element

[0602] 111 Minimum Search Department

[0603] 112 Weighted

[0604] 113,114 Storage

[0605] 120 Interference suppression unit

[0606] 121 Interference Detection Unit

[0607] 122 Synchronous determination unit

[0608] 123 Cycle detection unit.

Claims

1. A light detection device, comprising: a light receiving unit, receiving a first reflected light pulse signal within a first time range, wherein a first light pulse signal emitted at a first time interval is reflected by an object, and receiving a second reflected light pulse signal within a second time range different from the first time range, wherein a second light pulse signal emitted at a second time interval different from the first time interval is reflected by the object; as well as A histogram generator generates a first histogram and a second histogram, wherein the first histogram classifies the light receiving frequency of the first reflected light pulse signal received within the first time range for each predetermined fixed unit period, and the second histogram classifies the light receiving frequency of the second reflected light pulse signal received within the second time range for each unit period.

2. The light detection device according to claim 1, further comprising: A copy histogram generator generates a first copy histogram obtained by copying the first histogram by a first number corresponding to the first time interval, and generates a second copy histogram obtained by copying the second histogram by a second number corresponding to the second time interval.

3. The light detection device according to claim 2, in, the light receiving unit receives two or more reflected light pulse signals within two or more different time ranges, wherein two or more reflected light pulse signals emitted at two or more time intervals including the first time interval and the second time interval different from each other are reflected by the object, the histogram generator generates two or more histograms obtained by classifying the light reception frequencies of the two or more reflected light pulse signals received within two or more time ranges for each unit period, The copy histogram generator generates two or more copy histograms, wherein the two or more copy histograms are obtained by copying each of the two or more histograms by a number corresponding to the corresponding time interval. The two or more histograms generated by the histogram generator include the first histogram and the second histogram, and The two or more replica histograms generated by the replica histogram generator include the first replica histogram and the second replica histogram.

4. The light detection device according to claim 3, in, The light receiving section includes a plurality of pixels arranged in two or more in each of a first direction and a second direction, and Each of the plurality of pixels receives the two or more reflected light pulse signals within the two or more time ranges.

5. The light detection device according to claim 4, further comprising: a packet generator, generating ranging data including the two or more histograms in units of frames, The ranging data includes a start part, a plurality of groups and an end part. The beginning portion includes an identifier indicating a header of a frame and the number of the two or more time intervals, The packet includes a header, histogram data and a footer, the header includes an interval count of a corresponding histogram among the two or more histograms and a number of the plurality of pixels, the histogram data constitutes the corresponding histogram, and the footer includes end information of the corresponding histogram, and The end portion includes an identifier indicating an end of the frame.

6. The light detection device according to claim 4, further comprising: a packet generator, generating ranging data including the two or more histograms in units of frames, The ranging data includes a start part, a plurality of groups and an end part. The start portion includes an identifier indicating a header of a frame, a number of the plurality of pixels, and a number of the two or more time intervals, The packet includes a header, histogram data, and a trailer, the header including information indicating a pixel position, the histogram data constituting a corresponding histogram among the two or more histograms, and the trailer including end information of the corresponding histogram, and The end portion includes an identifier indicating an end of the frame.

7. The light detection device according to claim 4, further comprising: A distance measuring unit measures the distance of the object based on the light reception time when the light reception times corresponding to the peak positions of two or more replica histograms including the first replica histogram and the second replica histogram match each other, or the light reception time corresponding to the maximum peak position of a reconstructed histogram synthesized by aligning the interval counts of the two or more replica histograms.

8. The light detection device according to claim 7, in, The distance measuring unit adds the two or more replica histograms for each interval to generate the reconstructed histogram.

9. The light detection device according to claim 7, in, Each of the two or more replicate histograms has the same bin count, and The distance measuring section searches for a common section having a peak value of a light reception frequency in each of the two or more replica histograms, and generates a reconstructed histogram based on a minimum peak value in the searched section.

10. The light detection device according to claim 4, further comprising: a plurality of time-to-digital converters and a plurality of said histogram generators, arranged for each first pixel group including two or more said pixels arranged in said first direction, Each of the plurality of time-to-digital converters sequentially generates a digital signal according to the reception time of the two or more reflected light pulse signals received by each pixel in the corresponding first pixel group, and Each of the plurality of histogram generators generates the two or more histograms based on the digital signals sequentially generated by the corresponding time-to-digital converter.

11. The light detection device according to claim 10, in, A plurality of second pixel groups each including two or more pixels arranged in the second direction are arranged in the first direction, and A plurality of the second pixel groups are sequentially selected, and each pixel in the selected second pixel group inputs light reception signals corresponding to the two or more reflected light pulse signals to the plurality of time-to-digital converters in parallel.

12. The light detection device according to claim 11, in, Each pixel in the selected second pixel group sequentially outputs more than two light receiving signals according to more than two reflected light pulse signals within one frame period, and the light receiving signals output by corresponding pixels in the second pixel group are input to the plurality of time-to-digital converters in parallel.

13. The light detection device according to claim 4, further comprising: a plurality of said time-to-digital converters and a plurality of said histogram generators arranged for each said pixel, Each of the plurality of time-to-digital converters generates a digital signal corresponding to a reception time of the two or more reflected light pulse signals received by a corresponding pixel, and Each of the plurality of histogram generators generates the two or more histograms based on the digital signal generated by the corresponding time-to-digital converter.

14. The light detection device according to claim 13, in, Each of the plurality of pixels sequentially outputs two or more light receiving signals according to the two or more reflected light pulse signals within one frame period, and the light receiving signal outputs of the corresponding pixels are input to the plurality of time-to-digital converters in parallel.

15. The light detection device according to claim 10, in, The time-to-digital converter outputs a Gray code corresponding to the light reception time, and The histogram generator includes a conversion table for converting the Gray code into light reception time data.

16. The light detection device according to claim 3, further comprising: The storage unit stores the two or more replicated histograms having bin counts corresponding to the least common multiple of the two or more time intervals.

17. The light detection device according to claim 3, further comprising: The storage unit has a storage capacity corresponding to a bin count of the histogram, wherein the bin count corresponds to a maximum time interval among the two or more time intervals.

18. The light detection device according to claim 17, further comprising: an interval expansion unit that stores the histogram corresponding to the maximum time interval as a unit in the storage unit, expands the histogram corresponding to the two or more time intervals excluding the maximum time interval by the one unit, and stores the histogram in the storage unit; a peak detection section that, in a storage area of ​​the storage section including the two or more histograms corresponding to the two or more time intervals in each of the one cells, repeatedly detects a position where light reception times of peaks of the two or more histograms match each other for each of the plurality of the one cells; a maximum peak value detecting unit for detecting a maximum value of the peak value from among the plurality of the one units; a shifting unit, shifting the maximum value of the peak value to the center of the corresponding storage area; as well as A centroid calculation unit performs centroid calculation in the storage area shifted by the shift unit.

19. The light detection device according to claim 3, in, The histogram generator generates the two or more histograms based on the two or more reflected light pulse signals repeatedly obtained when the light pulse signal is repeatedly caused to emit light at each of the two or more time intervals, and flattens the number of frequencies except for peaks of the two or more histograms by periodically shifting a start time when the two or more histograms are generated.

20. The light detection device according to claim 7, further comprising: The interference detection unit detects whether there is interference caused by unknown optical pulse signals. Wherein, when the interference detection unit detects that there is no interference, the distance measurement unit measures the distance of the object based on the reconstructed histogram.

21. The light detection device according to claim 20, further comprising: a synchronization determination unit that determines whether synchronization with the cycle switching of the unknown optical pulse signal is possible when the interference is detected by the interference detection unit, When the synchronization determination unit determines that synchronization is possible, the histogram generator generates the two or more histograms in synchronization with the unknown optical pulse signal.

22. The light detection device according to claim 21, further comprising: a cycle detection unit, detecting a switching order of the cycle of the unknown optical pulse signal, The histogram generator generates the two or more histograms in a switching order in which the switching order of the cycles detected by the cycle detection unit is time-shifted or in a switching order different from the switching order of the cycles detected by the cycle detection unit.

23. The light detection device according to claim 21, further comprising: The light emission timing control unit controls the light emission timing of the optical pulse signal including the first optical pulse signal and the second optical pulse signal so as to reduce interference with the unknown optical pulse signal when the synchronization determination unit determines that synchronization is impossible.

24. The light detection device according to claim 23, in, The light emission timing control section randomizes a light emission period for generating two or more light pulse signals for each of the plurality of histograms included in each of the two or more replica histograms.

25. The light detection device according to claim 24, in, The light emission timing control section randomizes the light emission periods of the two or more optical pulse signals so that the total number of optical pulse signals used to generate the plurality of histograms is equal for each of the two or more replica histograms.

26. A distance measurement system, comprising: Light emitting device; as well as The light detection device according to claim 3, Wherein, the light emitting device comprises: A first light emitting unit, emitting a plurality of the first light pulse signals at the first time interval; and a second light emitting unit, emitting a plurality of the second light pulse signals at the second time interval; and The light detection device includes a light emission timing control unit, which controls the first light emission unit and the second light emission unit so that after the first light emission unit emits the first light pulse signal of a number corresponding to the first time range at the first time interval, the first light emission unit emits the second light pulse signal of a number corresponding to the second time range at the second time interval.

27. The distance measuring system according to claim 26, in, The light emitting device emits each of the two or more light pulse signals at the two or more time intervals by a number corresponding to the corresponding time range, and the light emission timing control section performs control to sequentially emit the two or more light pulse signals.

28. The distance measuring system according to claim 26, in, The optical detection device includes an interference detection unit for detecting an unknown optical pulse signal, and The light emission timing control section causes the light emitting device to emit light repeatedly in a sequence different from a sequence of the two or more time intervals at which the unknown light pulse signal detected by the interference detection section is emitted, or at time intervals different from the two or more time intervals.

29. The distance measuring system according to claim 28, in, The histogram generator generates the two or more histograms based on the unknown optical pulse signal when the light emitting device is not emitting light, and The interference detection section detects the presence or absence of interference due to the unknown optical pulse signal based on the two or more histograms.

30. A distance measurement system, comprising: A light emitting device comprising: a first light emitting unit that emits a plurality of first light pulse signals at first time intervals, and A second light emitting unit emits a plurality of second light pulse signals at a second time interval; a light receiving unit that receives a first reflected light pulse signal within a first time range, wherein the first light pulse signal is reflected by an object, and receives a second reflected light pulse signal within a second time range different from the first time range, wherein the first reflected light pulse signal is reflected by an object, and wherein the second reflected light pulse signal is reflected by an object at a second time interval different from the first time interval; and a grouping generator, generating distance measurement data having two or more histograms, wherein the two or more histograms include a first histogram generated based on the first reflected light pulse signal and a second histogram generated based on the second reflected light pulse signal in units of frames, wherein the distance measurement data includes a start portion, a plurality of groups, and an end portion, The start portion includes a header indicating a frame and an identifier of the number of two or more time intervals including the first time interval and the second time interval, The packet includes a header, histogram data and a trailer, the header includes the interval count of the corresponding histogram among the two or more histograms, the histogram data constitutes the corresponding histogram, the trailer includes the end information of the corresponding histogram, and The end portion includes an identifier indicating an end of the frame.

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