Distance measuring device and distance measuring method

Abstract

To provide a distance measuring device capable of detecting the light emitting cycle and light emitting period of the other distance measuring device in a short time, and a distance measuring method.SOLUTION: The distance measuring device has a function to detect interference with the other distance measuring device. The distance measuring device executes the exposure only while changing the timing at which pixels start to be exposed for detecting the interference detection period of the interference and the distance measurement period by light emission and exposure alternately. The distance measuring device is capable of detecting interference with the other distance measuring device without stopping the distance measurement function. The distance measuring device is configured so as to, when interference with other distance measuring devices is detected, automatically change the light-emitting cycle to eliminate the interference with the other distance measuring devices.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In order to measure the distance to an object and obtain a distance image, distance measuring devices using a method of measuring the distance by the time of flight (TOF: Time Of Flight) that it takes for an irradiated light to reflect off the object and return have been put to practical use. In order to measure the distance, the distance measuring device periodically repeats the emission of irradiated light and the exposure to reflected light, and calculates the time delay of the reflected light relative to the irradiated light from the amount of exposure accumulated during a specified exposure period to obtain the distance. In this case, if there are multiple distance measuring devices with the same emission cycle within the measurement range, the light intensities of each device will be strengthened, causing interference and making it impossible to measure the distance accurately. Therefore, if there are multiple distance measuring devices with the same emission cycle within the measurement range, it is necessary to prevent interference by changing the emission cycle for each distance measuring device.

[0003] A conventional technique related to the present invention is the distance measuring device of Patent Document 1 (hereinafter referred to as the "conventional distance measuring device"). The conventional distance measuring device measures the amount of exposed charge while changing the shift amount of the exposure gate, and sets the exposure gate shift amount at which the brightness is highest as the light emission exposure timing of the other distance measuring device. The conventional distance measuring device calculates the brightness variation of the exposed charge amount while changing the exposure gate period, and determines that the exposure gate period is the light emission period of the other distance measuring device based on the presence or absence of variation. The conventional distance measuring device then determines that 1 / 2 of the value of the exposure gate period when there is the smallest variation is the light emission period of the other distance measuring device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-165105 A Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional distance measuring devices, in order to detect the light emission cycle and light emission period of other distance measuring devices, multiple measurements are required while changing the exposure gate cycle, which means it takes a long time to detect the light emission cycle and light emission period of the other distance measuring device.

[0006] The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a distance measuring device and a distance measuring method that are capable of detecting the light emission cycle and light emission period of another distance measuring device in a short period of time. [Means for solving the problem]

[0007] In order to solve the above problem, the distance measuring device of the present invention is a distance measuring device that measures a distance based on a flight time of measurement light irradiated toward a measurement object until it is reflected by the measurement object and returns, and includes an irradiation unit that irradiates the measurement light to the measurement object, an image sensor including a plurality of pixels whose exposure and non-exposure are controlled, and a control device that controls the irradiation unit and the image sensor and acquires an exposure amount of the pixels from the image sensor. The control device executes a distance measurement period in which the irradiation unit emits the measurement light, the plurality of pixels perform exposure to light reflected by the measurement object with the measurement light, and calculates the distance based on the exposure amount, and an interference detection period in which the irradiation unit stops emitting the measurement light and the plurality of pixels perform exposure, and during the interference detection period, a light emission detection pixel group including a plurality of unit pixel units consisting of one pixel and a plurality of pixels controlled to perform the same exposure operation, which is composed of at least a portion of the plurality of pixels of the image sensor, and includes one of the light emission detection pixel groups or a plurality of front pixels included in the image sensor. The light emission detection pixel group is configured to control a plurality of pixels constituting the light emission detection pixel group so that, in each group of the light emission detection pixel group, either the exposure start timing or the exposure period of each unit pixel unit executes a light emission detection operation that operates differently from each other, and to identify, based on the amount of exposure detected by the light emission detection pixel group by executing the light emission detection operation, the exposure timing at which the unit pixel unit is exposed to light from another ranging device and the exposure duration for which the unit pixel unit is continuously exposed to light from the other ranging device, to calculate the light emission cycle of the other ranging device based on the exposure timing, and to calculate the light emission period of the other ranging device based on the exposure duration.

[0008] The distance measuring method of the present invention is a distance measuring method using a distance measuring device that measures a distance based on the time of flight of measurement light irradiated towards a measurement object until it is reflected by the measurement object and returns, and the distance measuring device comprises an irradiation unit that irradiates the measurement light to the measurement object, an image sensor including a plurality of pixels whose exposure and non-exposure are controlled, and a control device that controls the irradiation unit and the image sensor and acquires the exposure amount of the pixels from the image sensor, and the control device executes a distance measurement period in which the irradiation unit emits the measurement light and the plurality of pixels expose to light reflected by the measurement object with the measurement light, and calculates the distance based on the exposure amount, and an interference detection period in which the irradiation unit stops emitting the measurement light and the plurality of pixels expose, and during the interference detection period, a plurality of pixels of at least a portion of the plurality of pixels of the image sensor are exposed to light. a light emission detection pixel group that is composed of pixels and includes a plurality of unit pixel units each consisting of either a single pixel or a plurality of pixels controlled to perform the same exposure operation, and in one of the light emission detection pixel groups or each of the plurality of light emission detection pixel groups included in the image sensor, the plurality of pixels that constitute the light emission detection pixel group are controlled so that either the exposure start timing and the exposure period of each unit pixel unit executes a light emission detection operation that operates differently from each other, and based on the exposure amount detected by the light emission detection pixel group by executing the light emission detection operation, the exposure timing at which the unit pixel unit is exposed to light from another ranging device and the exposure duration time for which the unit pixel unit is continuously exposed to light from the other ranging device are identified, the light emission period of the other ranging device is calculated based on the exposure timing, and the light emission period of the other ranging device is calculated based on the exposure duration. Effect of the Invention

[0009] According to the present invention, it is possible to detect the light emission cycle and light emission period of another distance measuring device in a short time. Note that the effects described here are not necessarily limited to those described herein, and may be any of the effects described in this disclosure. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a distance measuring device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram for explaining the principle of distance measurement. [Diagram 3] FIG. 3 is a diagram for explaining the effect of interference on distance measurement. [Figure 4] FIG. 4 is a diagram for explaining conditions under which interference occurs between distance measuring devices. [Diagram 5] FIG. 5 is a diagram showing an example of a time chart for distance measurement by the distance measuring device. [Figure 6] FIG. 6 is a setting table showing the light emission periods and the corresponding light emission cycles of the distance measuring device. [Figure 7] FIG. 7 is a diagram for explaining the light emission detection period and distance measurement period of the other distance measuring device. [Figure 8] FIG. 8 is a diagram showing an example of a pixel of an image sensor. [Figure 9] FIG. 9 is a diagram for explaining the exposure gate of each pixel. [Figure 10A] FIG. 10A is a diagram for explaining an example of the amount of exposure when light from another distance measuring device is used for exposure. [Figure 10B] FIG. 10B is a diagram for explaining an example of the amount of exposure when light from another distance measuring device is used for exposure. [Figure 11] FIG. 11 is a diagram for explaining an operation pattern of the distance measuring device. [Figure 12] FIG. 12 is a flowchart showing a process flow executed by the control unit. [Figure 13] FIG. 13 is a flowchart showing a process flow executed by the control unit of the distance measuring device according to the second embodiment. [Figure 14] FIG. 14 is a diagram for explaining the exposure gate of each pixel. [Figure 15] FIG. 15 is a diagram for explaining an example of the amount of exposure when light from another distance measuring device is used for exposure. [Figure 16] FIG. 16 is a diagram for explaining an example of the result of subtracting the amount of exposure. [Figure 17] FIG. 17 is a diagram showing an example in which the emission detection pixel groups are arranged on a row-by-row basis. [Figure 18] FIG. 18 is a graph showing the amount of exposure of each pixel in the luminescence detection pixel group shown in FIG. [Figure 19] FIG. 19 is a graph showing the integrated results of the exposure amounts of pixels that perform exposure operations at the same timing. [Figure 20] FIG. 20 is a diagram showing an example in which a plurality of square-shaped emission detection pixel groups are arranged. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Each embodiment of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding parts may be given the same reference numerals. In the following description, various information may be described using expressions such as "tables", but the various information may be expressed using data structures other than these. In the following description, processing may be described using functional blocks as the subject, but the subject of the processing may be a CPU or a device (control device) instead of a functional block.

[0012] <<First embodiment>> A distance measuring device according to a first embodiment of the present invention will be described. FIG. 1 is a diagram showing an example of the configuration of a distance measuring device 10 according to a first embodiment of the present invention. As shown in FIG. 1, the distance measuring device 10 includes a control unit 11, a light emission control unit 12, an exposure control unit 13, a signal processing unit 17, a light emission unit 20, and a light receiving unit 21. The exposure control unit 13 includes an exposure gate cycle control unit 14, an exposure gate duty control unit 15, and an exposure gate shift control unit 16. The signal processing unit 17 includes a distance calculation unit 18 and an IR luminance measurement unit 19. For convenience of explanation, the distance measuring device 10 may be referred to as a "self-distance measuring device 10".

[0013] In FIG. 1, when the distance measuring device 10 measures the distance to an object 24 (object to be measured), irradiation light 23 such as a laser from a pulsed light emitting unit 20 is reflected by the object 24, and the reflected light 25 is exposed to an image sensor 22 (e.g., a CMOS sensor) having pixels arranged two-dimensionally on a light receiving unit 21, and converted into an electrical signal.

[0014] The image sensor 22 includes a plurality of pixels arranged in a grid pattern and a well-known readout circuit, and is configured to be able to change the exposure start timing and exposure period (the time during which exposure is continued from the exposure start timing) for each pixel. The image sensor 22 detects reflected light 25 that is generated when irradiation light 23 (pulsed light) is reflected by an object 24. The image sensor 22 exposes the reflected light 25 during a period (exposure gate) in which an exposure signal indicates an exposure operation, and converts the amount of exposure (amount of charge) at each pixel position of the image sensor 22 into an electrical signal and outputs it.

[0015] A distance calculation unit 18 of the signal processing unit 17 calculates a distance D from an output signal from an image sensor 22 of the light receiving unit 21. This distance D is calculated for each pixel on the image sensor 22. An IR luminance measurement unit 19 of the signal processing unit 17 detects the output signal from the light receiving unit 21 as IR (infrared) luminance.

[0016] The light emission control unit 12 controls the emission of the irradiation light 23 emitted from the light emission unit 20. The light emission unit 20 is, for example, a laser diode, and irradiates the target 24 with pulsed light having a wavelength in the infrared region as the measurement light 23. The light emission control unit 12 controls the light emission period and the extinction period of the pulsed light (rectangular pulsed light) output by the light emission unit 20 based on an exposure signal. Note that the light emission control unit 12 may output a light emission signal for controlling the light emission period and the extinction period to the light emission unit 20, and output an exposure signal indicating an exposure operation and a non-exposure operation to the image sensor 22, thereby controlling the light emission period and the extinction period of the light emission unit 20 and the exposure operation and non-exposure operation of the image sensor 22.

[0017] The exposure control unit 13 controls an exposure gate period (hereinafter also referred to as an exposure period) for the reflected light 25 at the light receiving unit 21. The exposure control unit 13 generates and outputs a pulsed exposure signal that indicates the exposure and non-exposure operations of each pixel.

[0018] Each pixel of the image sensor 22 is exposed to reflected light at the timing when the exposure signal indicates an exposure operation (exposure gate, which is the period for exposing light), and converts the amount of exposure (amount of charge) at each pixel position of the image sensor 22 into an electrical signal and outputs it. The exposure gate cycle control unit 14 controls the cycle of the exposure gate. The exposure gate duty control unit 15 controls the duty value of the exposure gate. The exposure gate shift control unit 16 controls the timing of the exposure gate.

[0019] The control unit 11 has a light emission and exposure setting table 600 (see FIG. 6) and other tables (not shown), and the light emission period, light emission duty value, exposure period, and exposure duty value in any table are selected according to instructions input by the user. The selected light emission and exposure setting values ​​are set by the control unit 11 to the light emission control unit 12 and exposure control unit 13 as light emission and exposure setting values ​​for controlling the light emission and extinguishing operations of the light emission unit 20 and the exposure and non-exposure operations of the image sensor 22 during the distance measurement period.

[0020] If another distance measuring device (measured device) 26 is present within the distance measuring range of the distance measuring device 10, the light emitted from the other distance measuring device 26 or its reflected light may become interference light 27 and enter the light receiving unit 21 of the distance measuring device 10. This interference light 27 will affect the distance D calculated by the distance calculation unit 18.

[0021] In order to prevent interference, it is necessary to change the light emission cycle for each distance measuring device. For this purpose, the distance measuring device 10 measures the light emission (light emission period and light emission cycle) of the other distance measuring device 26 .

[0022] The control unit 11, the light emission control unit 12, the exposure control unit 13, and the signal processing unit 17 of the distance measuring device 10 can be configured by a computer including a processor such as a CPU and a storage device (storage medium) such as a memory. For convenience, the control unit 11, the light emission control unit 12, the exposure control unit 13, and the signal processing unit 17 may also be referred to as a "control device." The CPU realizes the functions of the control unit 11, the light emission control unit 12, the exposure control unit 13, and the signal processing unit 17 by reading and executing a program stored in the memory. The control unit 11, the light emission control unit 12, the exposure control unit 13, and the signal processing unit 17 can be configured in part or in whole by hardware. For example, the control unit 11, the light emission control unit 12, the exposure control unit 13, and the signal processing unit 17 may be configured to realize at least a part of the functions of the control unit 11, the light emission control unit 12, the exposure control unit 13, and the signal processing unit 17 using an FPGA (Field Programmable Gate Array) or the like.

[0023] FIG. 2 is a diagram for explaining the principle of distance measurement. As shown in FIG. 2, distance measurement can calculate the distance D to the object 24 based on the time difference dT between the irradiated light 23 and the reflected light 25 as D=dT×c / 2, where c is the speed of light. The distance calculation unit 18 calculates the distance to the object 24 for each pixel based on the electrical signal (exposure amount) from the image sensor 22. Specifically, the distance calculation unit 18 can calculate the distance D as follows. As shown in FIG. 2, when the exposure operation is divided into two gates (exposure gate S1 and exposure gate S2) for one irradiation light (pulse width T0), the time difference dT can be obtained as the ratio of the charge amounts Q1 and Q2 accumulated in the image sensor 22 by the exposure gate S1 and exposure gate S2 to the pulse width T0 of the irradiation light, and is dT=T0×Q2 / (Q1+Q2). From these, the distance D can be calculated using formula (1) as D = T0 x Q2 / (Q1 + Q2) x c / 2.

[0024] Fig. 3 is a diagram for explaining the effect on distance measurement during interference. In Fig. 3, when the irradiation light or reflected light, which is the interference light 27 from the other distance measuring device 26, is exposed, an error occurs in the value of the distance D. That is, the amount of charge accumulated in the image sensor 22 at the exposure gate S1 and the exposure gate S2 due to the interference light from the other distance measuring device 26 becomes Q1+'Q1 and Q2+'Q2, respectively. Therefore, the value of the distance D becomes the value calculated by the formula (2), and an error occurs in the value of the distance D calculated by the formula (1).

[0025] Fig. 4 is a diagram for explaining conditions under which interference occurs between distance measuring devices. Fig. 4 shows the timing of the light emission exposure operations of two distance measuring devices 1 and 2. The distance measuring devices 1 and 2 each alternately perform a light emission exposure operation in which they emit irradiation light 23 to an object 24 and expose it to the reflected light 25, and a data output operation in which they output the charge exposed by the image sensor 22 to the signal processing unit 17. The light emission exposure period, which is the period during which the light emission exposure operation is performed, and the data output period, which is the period during which the data output operation is performed, constitute one frame.

[0026] When there is another distance measuring device 2 within the measurement range of the distance measuring device 1 and the light emission exposure period is the same, interference occurs. The effect of interference also depends on the time difference Tdif between the frames of the distance measuring device 1 and the frames of the distance measuring device 2. That is, when the time difference Tdif is small, the light emission exposure period of the distance measuring device 1 is the same as the light emission exposure period of the distance measuring device 2, and the light emission exposure periods overlap, the effect of interference is large, and when the time difference Tdif is large and the overlap of the light emission exposure periods is small, the effect of interference is small. Also, since there is an error in the reference clock of the distance measuring device, there is a slight difference in the time of one frame for each distance measuring device. Therefore, the time difference Tdif is not constant, and the overlap of the light emission exposure periods changes periodically.

[0027] Fig. 5 is a diagram showing an example of a time chart for distance measurement by a distance measuring device. In Fig. 5, the light emission exposure period includes an S1 period in which light emission and exposure gate S1 are repeated β times, and an S2 period in which light emission and exposure gate S2 are repeated β times. The S1 period and the S2 period together form one cycle, which is repeated α cycles. This β-times repetition period is the light emission exposure period, and if another distance measuring device 26 has the same period and the above-mentioned Tdif is small, interference will occur.

[0028] 6 is a setting table of the light emission period and the corresponding light emission cycle of the distance measuring device. As shown in FIG. 6, in the setting table 600, the light emission period To is T o1 , T o2 , T o3 , T o4 There are four types, and the corresponding light emission period Ti is Ti 1,1 ~Ti 1,5 , Ti 2,1 ~Ti 2,5 , Ti 3,1 ~Ti 3,5 , Ti 4,1 ~T 4,5 There are a combination of the above. The light emission period To is determined by the distance measurement range, and a non-overlapping value must be selected for the light emission cycle Ti to avoid interference with other distance measuring devices 26. The selected value is set by the control unit 11 to the light emission control unit 12 and exposure control unit 13. The light emission control unit 12 controls the light emission unit 20 to emit light or to be turned off in accordance with that value. The exposure control unit 13 controls the light receiving unit 21 to be exposed or not exposed in accordance with that value.

[0029] <Summary of the Invention> The distance measuring device 10 according to the first embodiment of the present invention has a function of detecting interference with another distance measuring device 26. As shown in FIG. 7, the distance measuring device 10 alternates between a light emission detection period (interference detection period) of another distance measuring device in which only exposure is performed by changing the exposure start timing of pixels to detect interference, and a distance measurement period by light emission and exposure. The distance measuring device 10 can detect interference with another distance measuring device 26 without stopping the distance measurement function. When the distance measuring device 10 detects interference with another distance measuring device 26, it automatically changes the light emission cycle to eliminate the interference with the other distance measuring device 26. The distance measurement period may be referred to as a "distance measurement frame". The light emission detection period of another distance measuring device may be referred to as a "light emission detection frame".

[0030] Since the distance measuring device 10 does not require light reception for several frames as in Patent Document 1 (JP Patent Publication 2022-165105 A), even if the normal distance measuring operation and the light emission cycle detection operation are alternately performed, the normal distance measurement frames can be secured within a practical range. For example, if the frame rate is 30 fps, 15 frames are distance measurement frames, and the remaining 15 frames can be allocated to light emission cycle detection (light emission detection frames) without any practical problems. In addition, if the light emission cycle detection (light emission detection frame) is executed for one frame out of 30 frames instead of alternately, the distance measurement frames can be maintained at approximately 30 fps.

[0031] When detecting interference with another distance measuring device, the distance measuring device controls the pixels of the image sensor so that a specific number of pixels perform an exposure operation for detecting light emission from the other distance measuring device.

[0032] When detecting the emission of light from the other distance measuring device 26, a specific number of pixels that perform a specific exposure operation are referred to as an emission detection pixel group. The number of emission detection pixel groups may be one or may be two or more. When there are a plurality of emission detection pixel groups, the number of pixels constituting each emission detection pixel group is the same. Note that the number of pixels constituting each emission detection pixel group may be different from each other. The number of pixels constituting each emission detection pixel group may be only partially different. For convenience, each of the multiple pixels (one pixel) constituting a emission detection pixel group may be referred to as a "unit pixel portion."

[0033] During the distance measurement period, the distance measuring device 10 controls the light emitting unit 20 to perform light emitting and extinguishing operations to measure the normal distance D, and controls all pixels of the image sensor 22 including the light emitting detection pixel group to perform exposure operations to measure the normal distance D, and during the light emitting detection period of the other distance measuring device, controls the light emitting unit 20 to stop emitting light, and controls multiple pixels among all pixels of the image sensor 22 that constitute the light emitting detection pixel group to perform exposure operations to detect the light emitting of the other distance measuring device 26.

[0034] An example of the exposure operation of a plurality of pixels constituting the emission detection pixel group will be described below with reference to Fig. 8 to Fig. 10A. Fig. 8 is a diagram showing an example of pixels of the image sensor 22. Fig. 9 is a diagram for explaining the exposure gate of each pixel. Fig. 10A is a diagram for explaining an example of the exposure amount when light from another distance measuring device 26 is used for exposure.

[0035] In this example, the emission detection pixel group is composed of pixels (0,1), (0,2), (0,3), (0,4), (0,5), and (0,6) in the top row of pixels of the image sensor 22, as shown in FIG.

[0036] The distance measuring device 10 detects the amount of exposure by the light from the other distance measuring device 26 by shifting the exposure start timing for each of the multiple pixels that make up the light emission detection pixel group. The distance measuring device 10 identifies the pixels exposed to the light from the other distance measuring device 26 based on the detected amount of exposure. The distance measuring device 10 measures the emission period and emission cycle of the light from the other distance measuring device 26 based on the identified pixels.

[0037] In this example, the distance measuring device 10 controls a plurality of pixels constituting the emission detection pixel group so that the exposure operation of the pixels that are exposed for the time Te from the time the exposure gate is turned on is started in a predetermined order with a delay of the time Te. Specifically, the distance measuring device 10 controls a plurality of pixels constituting the emission detection pixel group so that the timing of starting the exposure operation is delayed by the time Te in the horizontal order for the pixels (0,1), (0,2), (0,3), (0,4), (0,5), and (0,6) in the top row.

[0038] 9, the distance measuring device 10 controls the on and off of the exposure gate of each pixel as follows: After the exposure gate of pixel (0,1) is turned on for time Te, the exposure gate of pixel (0,2) is turned on for time Te, and then the exposure gate of pixel (0,3) is turned on for time Te. After that, the exposure gate of pixel (0,4) is turned on for time Te, and then the exposure gate of pixel (0,5) is turned on for time Te, and then the exposure gate of pixel (0,6) is turned on for time Te.

[0039] In this case, as shown in Fig. 10A, when the distance measuring device 10 detects the exposure amount at pixel (0,1) and pixel (0,5), it identifies pixel (0,1) and pixel (0,5) as pixels exposed to light from the other distance measuring device 26. The distance measuring device 10 calculates the time difference (=4 x Te) between the exposure start timing of pixel (0,1) and the exposure start timing of pixel (0,5) as the light emission period of the other distance measuring device 26. Since the pixels (0,1) and (0,5) do not continuously detect light from the other distance measuring device 26, the distance measuring device 10 sets the exposure period of the own distance measuring device 10 to the exposure duration for continuously exposing the light from the other distance measuring device 26, and calculates the light emission period of the other distance measuring device 26 to the same time Te as the exposure period (time Te) of the own distance measuring device 10.

[0040] 10B, when the distance measuring device 10 detects the amount of exposure at pixel (0,1) and pixel (0,2) and detects the amount of exposure at pixel (0,5) and pixel (0,6), it identifies pixels (0,1) and (0,2) as well as pixels (0,5) and (0,6) as pixels exposed to light from the other distance measuring device 26. The distance measuring device 10 calculates the time difference (=4×Te) between the exposure start timing of pixel (0,1) and the exposure start timing of pixel (0,5) as the light emission period of the other distance measuring device 26. Since pixel (0,1) and pixel (0,5) each continuously detect light from the other distance measuring device 26, the distance measuring device 10 determines the total exposure period of the pixels continuously detecting light from the other distance measuring device 26 as the exposure duration for continuous exposure to light from the other distance measuring device 26, and calculates the light emission period of the other distance measuring device 26 by the number of pixels continuously detecting light from the other distance measuring device 26 (=2)×Te (exposure period). As a result, the distance measuring device 10 calculates that the light emission cycle of the other distance measuring device 26 is 4×Te and the light emission period is 2×Te.

[0041] Using the method described above, the distance measuring device 10 controls the exposure operation of each pixel in the light emission detection pixel group during the light emission detection period (interference detection period) of the other distance measuring device, to expose it to light from the other distance measuring device 26, and can measure the light emission cycle and light emission period of the other distance measuring device 26 in a short period of time based on the exposure amount of the pixels exposed to the light.

[0042] 11 is a diagram for explaining the operation pattern of the distance measuring device 10. As described above, the distance measuring device 10 alternately performs the light emission detection operation of the other distance measuring device 26 and the distance measurement operation. The distance measurement period (one frame) during which the distance measurement operation is performed is composed of a light emission exposure period during which the light emitting unit 20 performs light emission and extinguishing operations at a predetermined light emission cycle and light emission period, and the pixels of the image sensor 22 perform exposure and non-exposure operations at a predetermined exposure cycle and exposure period, and a data output period during which the charges exposed by the image sensor 22 during the light emission exposure period are output to the signal processing unit 17.

[0043] The light emission detection period (one frame) of the other ranging device 26 performing the light emission detection operation is composed of an exposure period in which each pixel constituting the light emission detection pixel group is exposed for a predetermined time Te at a predetermined exposure start timing that differs from one another, and a data output period in which the charge exposed by the image sensor 22 during the exposure period is output to the signal processing unit 17.

[0044] As an example, the distance measuring device 10 according to the first embodiment performs an emission detection period (interference detection period) of another distance measuring device before a distance measurement period, as shown in Fig. 11. The distance measuring device 10 according to the first embodiment alternates between the emission detection of the other distance measuring device 26 and the distance measurement period, thereby quickly (in a short time) detecting the emission from the other distance measuring device 26 and making settings in advance so that no interference occurs in the distance measurement period following the emission detection period.

[0045] In addition, in the case of Example 1 shown in FIG. 11, the exposure period in the light emission detection period (interference detection period) of the other ranging device and the light emission exposure period of the other ranging device 26 are exactly the same, but even if the exposure period in the light emission detection period (interference detection period) of the other ranging device and the light emission exposure period of the other ranging device 26 are misaligned as in Example 2 shown in FIG. 11, light emission detection is possible. However, the ranging device 10 according to the first embodiment does not necessarily need to alternate between the light emission detection period and the distance measurement period, and may be able to arbitrarily set the cycle of the light emission detection period in consideration of the number of other ranging devices 26 that may cause interference and the opportunity for light to enter. In this case, the cycle of the light emission detection period can be set arbitrarily by displaying a graphic interface possessed by the ranging device 10 on an Internet browser, for example, by alternating between the light emission detection period and the distance measurement period, or by executing one light emission detection period every two distance measurement periods, or by executing one light emission detection period every ten distance measurement periods, or by not executing the light emission detection period. This cycle can also be set by a command using HTTP (Hypertext Transfer Protocol) methods that the distance measuring device 10 has.

[0046] <Specific operation> 12 is a flowchart showing the process flow executed by the control unit 11. The control unit 11 starts the process from step 1200 and proceeds to step 1201 to determine whether the distance measuring device 10 is in a state where light emission detection of the other distance measuring device 26 is stopped. The control unit 11 executes light emission detection (light emission detection frame) a predetermined number of times, and if light from the other distance measuring device 26 is not detected, it stops the light emission detection of the other distance measuring device 26. The number of times that light emission is not detected is counted by a light emission not detected counter that the control unit 11 has. The light emission not detected counter indicates the number of times that light emission detection frames for detecting light emission of the other distance measuring device 26 are executed and light from the other distance measuring device 26 is not detected.

[0047] When the distance measuring device 10 is in the state of stopping light emission detection, the distance measuring device 10 performs light emission and exposure for distance measurement. Therefore, in this case, the control unit 11 judges "Yes" in step 1201 and executes the processes of steps 1210 and 1211 described below in order, and then returns to step 1201.

[0048] Step 1210: The control unit 11 sets, in the light emission control unit 12, a light emission cycle and a light emission period for distance measurement, and sets, in the exposure control unit 13, an exposure cycle and an exposure period for distance measurement.

[0049] Step 1211: The control unit 11 controls the light emission control unit 12 so that the light emission unit 20 performs light emission for distance measurement at the light emission cycle and light emission period set in step 1210, and the control unit 11 controls the exposure control unit 13 so that the light receiving unit 21 performs exposure for distance measurement at the exposure cycle and exposure period set. As a result, the distance measuring device 10 performs light emission and exposure for distance measurement, and measures the distance D to the object 24 for each pixel.

[0050] If the distance measuring device 10 is not stopping light emission detection, the control unit 11 judges "No" in step 1201 and proceeds to step 1202 to judge whether the current frame is a light emission detection frame for detecting light emission from the other distance measuring device 26 or not.

[0051] If the current frame is not an emission detection frame for detecting the emission of the other distance measuring device 26, the current frame is a distance measurement frame for performing distance measurement. Therefore, in this case, the control unit 11 judges "No" in step 1202, executes the processes of steps 1210 and 1211 described above, and then returns to step 1201.

[0052] If the current frame is an emission detection frame for detecting emission of the other distance measuring device 26, the control unit 11 judges "Yes" in step 1202 and executes the processes of steps 1203 and 1204 described below in order, and then proceeds to step 1205.

[0053] Step 1203 : The control unit 11 sets, in the exposure control unit 13 , an exposure cycle and an exposure period for each pixel of the emission detection pixel group for detecting the emission of the other distance measuring device 26 .

[0054] Step 1204: The control unit 11 controls the light receiving unit 21 by the exposure control unit 13 so that each pixel of the light emission detection pixel group of the light receiving unit 21 performs the above-mentioned light emission detection exposure for detecting light emission from the other distance measuring device 26 at the exposure cycle and exposure period set. As a result, the distance measuring device 10 detects the light emission of the other distance measuring device 26.

[0055] When the control unit 11 proceeds to step 1205, it determines whether or not there is light emission from the other distance measuring device 26 based on the amount of exposure detected by each pixel of the light emission detection pixel group.

[0056] If light is emitted from the other distance measuring device 26, the control unit 11 judges "Yes" in step 1205 and executes the processes of steps 1206 and 1207 described below in order, and then proceeds to step 1208.

[0057] Step 1206: The control unit 11 initializes the value of the light emission undetection counter to "0".

[0058] Step 1207: The control unit 11 uses the signal processing unit 17 to identify the pixels exposed to the light of the other ranging device 26 based on the exposure amount of each pixel in the group of pixels for light emission detection, and detects the light emission cycle and light emission period of the other ranging device 26 based on the identified pixels using the method described above.

[0059] When the control unit 11 proceeds to step 1208, it judges whether or not the light emission period of the other ranging device 26 detected in step 1207 is close to the light emission period of the self ranging device 10. For example, it calculates the absolute value of the difference between the light emission period of the self ranging device 10 and the light emission period of the other ranging device 26 in step 1207, and judges whether or not the absolute value of the calculated difference is equal to or less than a threshold value. If the absolute value of the calculated difference is equal to or less than the threshold value, the control unit 11 judges that the light emission period of the other ranging device 26 is close to the light emission period of the self ranging device 10, and if the absolute value of the calculated difference is greater than the threshold value, the control unit 11 judges that the light emission period of the other ranging device 26 is not close to the light emission period of the self ranging device 10.

[0060] If the light emission period of the other distance measuring device 26 is close to that of the local distance measuring device 10, the control unit 11 judges "Yes" in step 1208, executes the processes of step 1209 described below and steps 1210 and 1211 described above in order, and then returns to step 1201.

[0061] Step 1209: The control unit 11 changes the setting of the light emission period and light emission period according to the setting table 600. In this example, the control unit 11 randomly selects a light emission period from the setting table 600, and changes the setting of the light emission period to the selected light emission period.

[0062] If the light emission cycle of the other distance measuring device 26 is not close to the light emission cycle of the local distance measuring device 10, the control unit 11 judges "No" in step 1208, executes the processes of steps 1210 and 1211 described above in order, and then returns to step 1201.

[0063] If there is no light emission from the other distance measuring device 26 in the process of step 1205 described above, the control unit 11 determines "No" in step 1205 and proceeds to step 1212. When the control unit 11 proceeds to step 1212, it increments the value of the light emission non-detection counter by "1" and proceeds to step 1213.

[0064] When the control unit 11 proceeds to step 1213, it judges whether or not the value of the light emission non-detection counter has exceeded the threshold value.

[0065] If the value of the light emission undetection counter does not exceed the threshold value, the control unit 11 determines “No” in step 1213 , executes the processes of steps 1210 and 1211 described above, and then returns to step 1201 .

[0066] If the value of the light emission undetection counter exceeds the threshold value, the control unit 11 judges "Yes" in step 1213, executes the processes of step 1214 described below and steps 1210 and 1211 described above, and then returns to step 1201.

[0067] Step 1214: The control unit 11 stops the light emission detection of the other distance measuring device 26. When the light emission detection is stopped, the light emission detection frame is no longer executed, and the distance measuring device 10 performs only the distance measurement frame. In other words, if light emission from the other distance measuring device 26 cannot be detected for a certain period of time, the light emission detection itself is stopped. The above-mentioned graphic interface and commands may be used to set the threshold value.

[0068] <Effects> As described above, the distance measuring device 10 according to the first embodiment of the present invention can detect the emission of the other distance measuring device 26 in a short time without the need to perform multiple measurements while changing the exposure cycle to detect the emission of the other distance measuring device 26. In contrast, Patent Document 1 (JP Patent Publication No. 2022-165105) shows a method for detecting the emission cycle and emission period of the other distance measuring device 26 that causes interference, but it takes time to perform multiple measurements while changing the exposure cycle to detect the emission cycle and emission period. The distance measuring device 10 according to the first embodiment of the present invention operates so that the exposure start timing of each pixel of the emission detection pixel group of the image sensor 22 is delayed by a time Te in a predetermined order, and identifies the pixel exposed to the light of the other distance measuring device 26. Since the exposure timing of the identified pixel is known in the distance measuring device 10 according to the first embodiment, if the time difference between the exposure timings of the two identified pixels is calculated, the time difference can be calculated as the emission cycle of the light emitted by the other distance measuring device 26, and further, the emission period of the light emitted by the other distance measuring device 26 can be calculated by the above-mentioned method. As a result, the distance measuring device 10 according to the first embodiment does not need to perform measurements multiple times while changing the exposure cycle, which was necessary in the distance measuring device of Patent Document 1. Therefore, the distance measuring device 10 according to the first embodiment can detect the light emission (light emission cycle and light emission period) of the other distance measuring device 26 in a short time.

[0069] <<Second embodiment>> A distance measuring device 10 according to a second embodiment of the present invention will be described. The distance measuring device 10 according to the second embodiment of the present invention differs from the distance measuring device 10 according to the first embodiment only in that the distance measuring device 10 executes the process flow shown in the flowchart of Fig. 13 instead of the process flow shown in the flowchart of Fig. 12. The following description will focus mainly on this difference.

[0070] FIG. 13 is a flowchart showing a processing flow executed by the control unit 11 of the distance measuring device 10 according to the second embodiment. This flowchart is the same as that of FIG. 12, except that step 1209 of FIG. 12 is replaced with step 1309 of FIG. 13. If the light emission cycle is close to the cycle of the device itself in the process of step 1208, the control unit 11 judges "Yes" in step 1208 and proceeds to step 1309 to delay the start timing of distance measurement (distance measurement period). This allows the distance measuring device 10 to prevent interference by increasing the time difference of the distance measurement period, which is one of the factors that cause interference. Thereafter, the control unit 11 executes the processes of steps 1210 and 1211 described above, and then returns to step 1201.

[0071] <Effects> As described above, the distance measuring device 10 according to the second embodiment of the present invention can prevent interference by increasing the time difference between distance measurement periods, which is one of the factors that cause interference. The distance measuring device 10 according to the second embodiment employs a method of delaying the start timing of distance measurement by the distance measuring device 10 itself as a means for increasing this time difference.

[0072] <<Third embodiment>> A distance measuring device 10 according to a third embodiment of the present invention will be described below. The distance measuring device 10 according to the third embodiment differs from the distance measuring device 10 according to the first embodiment only in the following points.

[0073] In the distance measuring device 10 according to the third embodiment, the pixels constituting the light emission detection pixel group start exposure at the same timing, and perform exposure operations such that the exposure gates of the pixels are increased by a time Te in a predetermined order. The following description will focus on this difference.

[0074] As shown in FIG. 14, the control unit 11 sets the on-period of the exposure gate of each pixel as follows: The control unit 11 sets the on-period of the exposure gate of the reference pixel (0,1) to time Te. The control unit 11 sets the on-period of the exposure gate of the pixels other than the reference pixel (0,1) to increase by time Te each time the pixel position shifts by one column from the reference pixel. Specifically, the control unit 11 sets the on-period of the exposure gate of the pixel (0,2) that is shifted by one column horizontally from the reference pixel (0,1) to time 2Te (=Te+Te). The control unit 11 sets the on-period of the exposure gate of the pixel (0,3) that is shifted by two columns horizontally from the reference pixel (0,1) to time 3Te (=Te+Te+Te). The control unit 11 sets the on-period of the exposure gate of pixel (0,4) which is shifted horizontally by three columns from the reference pixel (0,1) to time 4Te (=Te+Te+Te+Te). The control unit 11 sets the on-period of the exposure gate of pixel (0,5) which is shifted horizontally by four columns from the reference pixel (0,1) to time 5Te (=Te+Te+Te+Te+Te). The control unit 11 sets the on-period of the exposure gate of pixel (0,6) which is shifted horizontally by five columns from the reference pixel (0,1) to time 6Te (=Te+Te+Te+Te+Te+Te).

[0075] In this case, for example, after the exposure of pixel (0,4) is completed as shown in Fig. 15, the amount of exposure received by pixel (0,5) is the amount of exposure of pixel (0,4) minus the amount of exposure of pixel (0,5). By subtracting the amount of exposure of the pixel that was previously exposed from each pixel in this manner, the pixels exposed to the light of the other distance measuring device 26 are identified as pixel (0,1) and pixel (0,5) as shown in Fig. 16. Based on the exposure timing (difference in exposure timing) of the identified pixels (0,1) and (0,5) to the light from the other distance measuring device 26 and the time Te, the distance measuring device 10 can calculate that the light emission cycle of the other distance measuring device 26 is 4 x Te and that the light emission period is Te.

[0076] <Effects> As described above, the distance measuring device 10 of the third embodiment of the present invention, like the first embodiment, can detect the light emission of the other distance measuring device 26 in a short period of time without having to perform multiple measurements while changing the exposure period in order to detect the light emission of the other distance measuring device 26.

[0077] <<Fourth embodiment>> A distance measuring device 10 according to a fourth embodiment of the present invention will be described below. The distance measuring device 10 according to the fourth embodiment differs from the distance measuring device 10 according to the first embodiment only in the following points.

[0078] The distance measuring device 10 according to the fourth embodiment arranges a plurality of light emission detection pixel groups in horizontal rows on the image sensor 22. The number of pixels constituting the plurality of light emission detection pixel groups in rows is the same as each other. The order of exposure of the plurality of pixels constituting the light emission detection pixel groups is determined, and exposure is performed in the determined order with a time Te shift. For example, the light emission detection pixel group is composed of nine pixels in the same row, and the exposure order is determined so that exposure is performed in order from left to right, and exposure is performed in the determined order with a time Te shift. The distance measuring device 10 may integrate the exposure amount of pixels in the light emission detection pixel groups that have the same order of exposure (pixels with the same exposure start timing) in the plurality of light emission detection pixel groups. In this case, the distance measuring device 10 identifies the pixels exposed to the light of the other distance measuring device 26 based on the integrated exposure amount, and calculates the light emission cycle and light emission period of the other distance measuring device 26 based on the identified pixels and the time Te.

[0079] The following description will focus on these differences.

[0080] The light from the other distance measuring device 26 may not be evenly irradiated to all pixels of the image sensor 22 of the self distance measuring device 10, but may be irradiated to a certain area. In order to detect the light emission cycle of the other distance measuring device 26 in that area, it is necessary that there are a number of pixels in that area such that the number of pixels x time Te is equal to the length of the light emission cycle of the other distance measuring device 26.

[0081] Therefore, the distance measuring device 10 according to the fourth embodiment arranges a plurality of light emission detection pixel groups on the image sensor 22 so that the light emission detection pixel groups are positioned in an area illuminated with light from the other distance measuring device 26. This increases the chance that the light from the other distance measuring device 26 will strike an area (light emission detection pixel group) required for measuring the light emission period of the other distance measuring device 26.

[0082] Fig. 17 is a diagram showing an example in which a group of light emission detection pixels is arranged by row. As shown in Fig. 17, in this example, exposure is set for pixels (0,0) to (0,8) for every time Te. In this case, the light emission period from the other distance measuring device 26 can be detected from Te to 8 x Te. Also, exposure is performed not only for the single horizontal row from pixels (0,0) to (0,8), but also for each row from pixels (1,0) to (1,8) to pixels (8,0) to (8,8) with the same exposure start timing and exposure period.

[0083] Specifically, the control unit 11 sets the exposure gate of each pixel of the image sensor 22 for the pixels in the 0th row: pixel (0,0), pixel (0,1), pixel (0,2), pixel (0,3), pixel (0,4), pixel (0,5), pixel (0,6), pixel (0,7), and pixel (0,8) to time Te. The control unit 11 turns on the exposure gate of the leftmost pixel first, and delays the timing of turning on the exposure gate of the pixel shifted by N columns horizontally from the leftmost pixel by time Te×N from the timing of turning on the exposure gate of the leftmost pixel.

[0084] The control unit 11 sets the exposure gate of each pixel of the image sensor 22 of the pixels in the first row, pixel (1,0), pixel (1,1), pixel (1,2), pixel (1,3), pixel (1,4), pixel (1,5), pixel (1,6), pixel (1,7), and pixel (1,8), to time Te, in the same manner as the pixels in the 0th row. The control unit 11 turns on the exposure gate of the leftmost pixel first, and delays the timing of turning on the exposure gate of the pixel shifted by N columns in the horizontal direction from the leftmost pixel by time Te×N from the timing of turning on the exposure gate of the leftmost pixel. The control unit 11 turns on and off the exposure gate of each pixel of the pixels in the 2nd row to the 8th row, in the same manner as the pixels in the 0th row and the 1st row.

[0085] The exposure amount of a pixel that receives light from the other distance measuring device 26 is S, and the exposure amount of a pixel that does not receive light from the other distance measuring device 26 is N. The larger the difference between S and N, the easier it is to determine whether or not a pixel is exposed to light from another device, and the easier it is to detect the light emission cycle.

[0086] Therefore, in order to clarify the difference between S and N, the distance measuring device 10 according to the fourth embodiment may integrate the exposure amounts of pixels in each light emission detection pixel group that start exposure at the same timing. This allows the distance measuring device 10 to improve the relationship between S and N, thereby improving the measurement sensitivity.

[0087] Fig. 18 is a graph showing the amount of exposure of each pixel when light is received in the second and seventh columns, respectively, for pixels (0,0) to (0,8), pixels (1,0) to (1,8), and pixels (2.0) to (2,8) of the luminescence detection pixel group shown in Fig. 17. Line L0 shows the amount of exposure of each pixel from pixel (0,0) to pixel (0,8). Line L1 shows the amount of exposure of each pixel from pixel (1,0) to pixel (1,8). Line L2 shows the amount of exposure of each pixel from pixel (2,0) to pixel (2,8).

[0088] The interval between the peaks in the graph shown in FIG. 18 corresponds to the light emission period of the other distance measuring device 26, but there may be cases where the difference between S and N is small. In that case, in order to clarify the difference between S and N, the exposure amount of the pixels having the same exposure start timing of each light emission detection pixel group is integrated. FIG. 19 shows the result of integrating the exposure amount of the pixels having the same exposure timing, that is, pixels (0,0) to (0,8), pixels (1,0) to (1,8), and pixels (2.0) to (2,8). As shown in FIG. 19, it can be seen that such a method can improve the relationship between S and N. Therefore, the distance measuring device 10 can easily identify the pixels exposed to the light of the other distance measuring device 26.

[0089] <Effects> As described above, the distance measuring device 10 according to the fourth embodiment can increase the chance that light from the other distance measuring device 26 hits an area (light emission detection pixel group) required for measuring the light emission period of the other distance measuring device 26 by arranging multiple light emission detection pixel groups on the image sensor 22. Furthermore, the distance measuring device 10 according to the fourth embodiment can improve measurement sensitivity by integrating the exposure amounts of pixels that are exposed at the same timing.

[0090] <<Fifth embodiment>> A distance measuring device 10 according to a fifth embodiment of the present invention will be described below. The distance measuring device 10 according to the fifth embodiment differs from the distance measuring device 10 according to the fourth embodiment only in the following points.

[0091] The distance measuring device 10 according to the fourth embodiment has a plurality of rows of light emission detection pixel groups arranged therein, whereas the distance measuring device 10 according to the fifth embodiment has a plurality of square light emission detection pixel groups arranged therein.

[0092] As shown in FIG. 20, the multiple pixels of the image sensor 22 are arranged as square-shaped light emission detection pixel groups, namely a first light emission detection pixel group (area 0,0), a second light emission detection pixel group (area 0,1), a third light emission detection pixel group (area 0,2), a fourth light emission detection pixel group (area 1,0), a fifth light emission detection pixel group (area 1,1), a sixth light emission detection pixel group (area 1,2), a seventh light emission detection pixel group (area 2,0), an eighth light emission detection pixel group (area 2,1) and a ninth light emission detection pixel group (area 2,2).

[0093] The first emission detection pixel group (area 0,0) includes pixel (0,0), pixel (0,1), and pixel (0,2), as well as pixel (1,0), pixel (1,1), and pixel (1,2), as well as pixel (2,0), pixel (2,1), and pixel (2,2). The control unit 11 delays the exposure start timing by time Te in the order of pixel (0,0), pixel (0,1), and pixel (0,2), as well as pixel (1,0), pixel (1,1), and pixel (1,2), as well as pixel (2,0), pixel (2,1), and pixel (2,2), and controls each pixel to perform exposure for time Te.

[0094] The second emission detection pixel group (region 0,1) includes pixel (0,3), pixel (0,4), and pixel (0,5), as well as pixel (1,3), pixel (1,4), and pixel (1,5), as well as pixel (2,3), pixel (2,4), and pixel (2,5). The control unit 11 delays the exposure start timing by time Te in the order of pixel (0,3), pixel (0,4), and pixel (0,5), as well as pixel (1,3), pixel (1,4), and pixel (1,5), as well as pixel (2,3), pixel (2,4), and pixel (2,5), and controls each pixel to perform exposure for time Te.

[0095] The third emission detection pixel group (region 0,2) includes pixel (0,6), pixel (0,7), and pixel (0,8), as well as pixel (1,6), pixel (1,7), and pixel (1,8), as well as pixel (2,6), pixel (2,7), and pixel (2,8). The control unit 11 delays the exposure start timing by time Te in the order of pixel (0,6), pixel (0,7), and pixel (0,8), as well as pixel (1,6), pixel (1,7), and pixel (1,8), as well as pixel (2,6), pixel (2,7), and pixel (2,8), and controls each pixel to perform exposure for time Te.

[0096] The fourth emission detection pixel group (region 1,0) includes pixel (3,0), pixel (3,1), and pixel (3,2), as well as pixel (4,0), pixel (4,1), and pixel (4,2), and pixel (5,0), pixel (5,1), and pixel (5,2). The control unit 11 delays the exposure start timing by time Te in the order of pixel (3,0), pixel (3,1), and pixel (3,2), as well as pixel (4,0), pixel (4,1), and pixel (4,2), and as well as pixel (5,0), pixel (5,1), and pixel (5,2), and controls each pixel to perform exposure for time Te.

[0097] The fifth emission detection pixel group (region 1,1) includes pixel (3,3), pixel (3,4), and pixel (3,5), as well as pixel (4,3), pixel (4,4), and pixel (4,5), as well as pixel (5,3), pixel (5,4), and pixel (5,5). The control unit 11 delays the exposure start timing by time Te in the order of pixel (3,3), pixel (3,4), and pixel (3,5), as well as pixel (4,3), pixel (4,4), and pixel (4,5), as well as pixel (5,3), pixel (5,4), and pixel (5,5), and controls each pixel to perform exposure for time Te.

[0098] The sixth emission detection pixel group (region 1,2) includes pixel (3,6), pixel (3,7), and pixel (3,8), as well as pixel (4,6), pixel (4,7), and pixel (4,8), as well as pixel (5,6), pixel (5,7), and pixel (5,8). The control unit 11 delays the exposure start timing by time Te in the order of pixel (3,6), pixel (3,7), and pixel (3,8), as well as pixel (4,6), pixel (4,7), and pixel (4,8), as well as pixel (5,6), pixel (5,7), and pixel (5,8), and controls each pixel to perform exposure for time Te.

[0099] The seventh emission detection pixel group (region 2,0) includes pixels (6,0), (6,1), and (6,2), as well as pixels (7,0), (7,1), and (7,2), as well as pixels (8,0), (8,1), and (8,2). The control unit 11 delays the exposure start timing by time Te in the order of pixels (6,0), (6,1), and (6,2), as well as pixels (7,0), (7,1), and (7,2), as well as pixels (8,0), (8,1), and (8,2), so that each pixel performs exposure for time Te.

[0100] The eighth emission detection pixel group (region 2,1) includes pixel (6,3), pixel (6,4), pixel (6,5), as well as pixels (7,3), pixel (7,4), pixel (7,5), and pixels (8,3), pixel (8,4), and pixel (8,5). The control unit 11 delays the exposure start timing by time Te in the order of pixel (6,3), pixel (6,4), and pixel (6,5), as well as pixels (7,3), pixel (7,4), and pixel (7,5), and as well as pixels (8,3), pixel (8,4), and pixel (8,5), and controls each pixel to perform exposure for time Te.

[0101] The ninth emission detection pixel group (region 2,2) includes pixel (6,6), pixel (6,7), and pixel (6,8), as well as pixel (7,6), pixel (7,7), and pixel (7,8), as well as pixel (8,6), pixel (8,7), and pixel (8,8). The control unit 11 delays the exposure start timing by time Te in the order of pixel (6,6), pixel (6,7), and pixel (6,8), as well as pixel (7,6), pixel (7,7), and pixel (7,8), as well as pixel (8,6), pixel (8,7), and pixel (8,8), so as to control each pixel to perform exposure for time Te.

[0102] As in the fourth embodiment, the distance measuring device 10 may integrate the amounts of exposure of pixels in the same order of exposure among a plurality of light emission detection pixel groups.

[0103] Specifically, the distance measuring device 10 integrates the exposure amounts of pixels (0,0), (0,3), (0,6), (3,0), (3,3), (3,6), (6,0), (6,3), and (6,6). The distance measuring device 10 integrates the exposure amounts of pixels (0,1), (0,4), (0,7), (3,1), (3,4), (3,7), (6,1), (6,4), and (6,7). The distance measuring device 10 integrates the exposure amounts of pixels (0,2), (0,5), (0,8), (3,2), (3,5), (3,8), (6,2), (6,5), and (6,8).

[0104] The distance measuring device 10 integrates the amounts of exposure of pixels (1,0), (1,3), (1,6), (4,0), (4,3), (4,6), (7,0), (7,3), and (7,6). The distance measuring device 10 integrates the amounts of exposure of pixels (1,1), (1,4), (1,7), (4,1), (4,4), (4,7), (7,1), (7,4), and (7,7). The distance measuring device 10 integrates the amounts of exposure of pixels (1,2), (1,5), (1,8), (4,2), (4,5), (4,8), (7,2), (7,5), and (7,8).

[0105] The distance measuring device 10 integrates the amounts of exposure of pixels (2,0), (2,3), (2,6), (5,0), (5,3), (5,6), (8,0), (8,3), and (8,6). The distance measuring device 10 integrates the amounts of exposure of pixels (2,1), (2,4), (2,7), (5,1), (5,4), (5,7), (8,1), (8,4), and (8,7). The distance measuring device 10 integrates the amounts of exposure of pixels (2,2), (2,5), (2,8), (5,2), (5,5), (5,8), (8,2), (8,5), and (8,8).

[0106] As in the fourth embodiment, the distance measuring device 10 identifies the pixel that detected the light of the other distance measuring device 26 based on the accumulated exposure amount, and calculates the light emission cycle and light emission period of the other distance measuring device 26 based on the identified pixel and time Te.

[0107] <Effects> As described above, the distance measuring device 10 according to the fifth embodiment, like the fourth embodiment, arranges a plurality of light emission detection pixel groups on the image sensor 22, thereby increasing the chance that light from the other distance measuring device 26 will strike an area (light emission detection pixel group) required for measuring the light emission period of the other distance measuring device 26. Furthermore, like the fourth embodiment, the distance measuring device 10 according to the fifth embodiment can improve measurement sensitivity by integrating the exposure amounts of pixels exposed at the same timing.

[0108] <<Modifications>> The present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. Furthermore, the above-described embodiments and the following modifications can be combined with each other without departing from the scope of the present invention.

[0109] In each of the above embodiments, the distance measuring device 10 may alternate between one light emission detection frame and multiple distance measurement frames, or may alternate between multiple light emission detection frames and one distance measurement frame. The distance measuring device 10 may alternate between multiple (=N1) light emission detection frames and multiple (N2) distance measurement frames. In this case, the distance measuring device 10 may set N1 and N2 to be the same, N2 to be less than N1, or N2 to be more than N1.

[0110] In each of the above embodiments, the distance measuring device 10 may be configured to be set to either a first control state in which the distance measuring frame and the light emission detection frame are performed, or a second control state in which only the distance measuring frame is performed. In this case, the control unit 11 of the distance measuring device 10 may be configured to be able to switch between the first control state and the second control state based on a user operation on a user terminal capable of communicating with the distance measuring device 10 or an operation unit included in the distance measuring device 10.

[0111] In each of the above embodiments, the control unit 11 of the distance measuring device 10 may be configured to be able to set the number of times the distance measurement period (distance measurement frames) and the number of times the interference detection period (light emission detection frames) are executed within a predetermined time (for example, 1 second) to any number of times. In this case, the control unit 11 of the distance measuring device 10 may be able to set the number of times the distance measurement period (distance measurement frames) and the number of times the interference detection period (light emission detection frames) are executed according to an instruction input based on a user operation on a user terminal capable of communicating with the distance measuring device 10 or an operation unit included in the distance measuring device 10.

[0112] In the first to fourth embodiments, the shape of the luminescence detection pixel group may be radial, concentric, spiral, rectangular, or the like.

[0113] In each of the above embodiments, the control unit 11 of the distance measuring device 10 may be configured to be able to change at least one of the shape of the light emission detection pixel group, the position of the light emission detection pixel group, the number of light emission detection pixel groups, and the number of multiple pixels constituting the light emission detection pixel group every time a certain number of frames are executed.

[0114] In each of the above embodiments, the control unit 11 of the ranging device 10 may be configured to be able to change at least one of the shape of the light emission detection pixel group, the position of the light emission detection pixel group, the number of light emission detection pixel groups, and the number of pixels constituting the light emission detection pixel group, based on instructions input based on user operation of a user terminal capable of communicating with the ranging device 10 or an operation unit provided in the ranging device 10.

[0115] In the fourth and fifth embodiments, the plurality of pixels in the lattice pattern of the image sensor 22 may include a mixture of groups of light emission detection pixels having different shapes.

[0116] In each of the above embodiments, the luminescence detection pixel group may be configured by a plurality of "a plurality of pixels controlled to perform the same exposure operation." For convenience, the "a plurality of pixels controlled to perform the same exposure operation" may also be referred to as a "unit pixel portion." For example, the luminescence detection pixel group may include, as unit pixel portions, a plurality of square blocks each made up of a plurality of pixels performing the same exposure operation, and the exposure timing of the plurality of unit pixel portions (square blocks) constituting the luminescence detection pixel group may be controlled to be delayed by a time Te in a predetermined order.

[0117] In this case, the distance measuring device 10 may identify a unit pixel unit (square block) exposed to light from the other distance measuring device 26, and detect the light emission cycle and light emission period of the other distance measuring device 26 based on the exposure timing and time Te of the identified unit pixel unit (square block). Note that the unit pixel unit (block) does not have to be square-shaped, and may be, for example, in a vertical or horizontal row.

[0118] In each of the above embodiments, when the control unit 11 of the distance measuring device 10 does not detect any light emission from another distance measuring device 26 for a predetermined period of time, the control unit 11 may set the number of times the distance measurement period is executed and the number of times the interference detection period is executed within a predetermined time so that the number of times the interference detection period is executed is less than the number of times the distance measurement period is executed.

[0119] In each of the above embodiments, the distance measuring device 10 may be mounted on a moving object such as a vehicle. In this case, the distance measuring device 10 can detect interference even during normal operation, so that, for example, even if moving objects mounted with the distance measuring device 10 happen to come close to each other within a distance where interference may occur, the interference can be instantly avoided.

[0120] In each of the above embodiments, the distance measuring device 10 may be equipped with an acceleration sensor. In this case, the acceleration sensor provided in the distance measuring device 10 determines whether the distance measuring device 10 is stationary or moving (moving), and if the distance measuring device 10 is stationary, the light emission detection is stopped or the frequency of light emission detection is reduced, and if the distance measuring device 10 is moving, the frequency of light emission detection is increased. For example, when the distance measuring device 10 is mounted on a moving body, if the distance measuring device 10 moves together with the moving body, the movement may increase the possibility of encountering another distance measuring device 26 that may cause interference. Therefore, when it is determined that the distance measuring device 10 is moving, it is preferable to increase the frequency of light emission detection.

[0121] For example, the control unit 11 may determine whether the self-distance measuring device 10 is moving or not based on the acceleration acquired by the acceleration sensor, and if the self-distance measuring device 10 is not moving, may make the execution frequency of the interference detection period less than the execution frequency of the distance measurement period, or may stop the execution of the interference detection period, and if the self-distance measuring device 10 is moving, may make the execution frequency of the interference detection period more than the execution frequency of the distance measurement period. Note that these execution frequency settings can also be set to any value using the above-mentioned graphic interface and commands. [Explanation of symbols]

[0122] 10... distance measuring device, 11... control unit, 12... light emission control unit, 13... exposure control unit, 14... exposure gate period control unit, 15... exposure gate duty control unit, 16... exposure gate shift control unit, 17... signal processing unit, 18... distance calculation unit, 19... IR brightness measurement unit, 20... light emission unit, 21... light receiving unit, 22... image sensor, 26... device to be measured

Claims

1. A distance measuring device that measures a distance based on a flight time of a measurement light irradiated toward a measurement object until the measurement light is reflected by the measurement object and returns, an irradiation unit that irradiates the measurement object with the measurement light; an image sensor including a plurality of pixels whose exposure and non-exposure are controlled; a control device that controls the irradiation unit and the image sensor and obtains an exposure amount of a pixel from the image sensor; Equipped with The control device includes: a distance measurement period in which the irradiation unit emits the measurement light, the plurality of pixels perform exposure to light reflected by the measurement object from the measurement light, and the distance is calculated based on the amount of exposure; and an interference detection period in which the irradiation unit stops emitting the measurement light, and the plurality of pixels perform exposure, During the interference detection period, a light emission detection pixel group including a plurality of unit pixel portions each composed of one pixel or a plurality of pixels controlled to perform the same exposure operation, the unit pixel portion being composed of at least a portion of the plurality of pixels of the image sensor, the light emission detection pixel group being controlled to perform the same exposure operation, the light emission detection pixel group being controlled so that, in the one light emission detection pixel group or each of the plurality of light emission detection pixel groups included in the image sensor, any of the exposure start timings and exposure periods of each unit pixel portion are different from each other to perform light emission detection operations; identifying an exposure timing at which the unit pixel unit is exposed to light from another distance measuring device and an exposure duration at which the unit pixel unit is continuously exposed to light from the other distance measuring device based on the exposure amount detected by the light emission detection pixel group by executing the light emission detection operation; calculating a light emission period of the other distance measuring device based on the exposure timing, and calculating a light emission period of the other distance measuring device based on the exposure duration; It was configured as follows: Ranging device.

2. 2. The distance measuring device according to claim 1, The control device includes: During the interference detection period, controlling a plurality of pixels constituting the emission detection pixel group so as to execute a first emission detection operation in which, in one of the emission detection pixel groups or in each of the plurality of emission detection pixel groups included in the image sensor, the exposure start timings of the unit pixel units are different from one another, the unit pixel units start exposure in a predetermined order, and the exposure periods of the unit pixel units are the same as one another; identifying the unit pixel portion exposed to the light of the other distance measuring device based on the amount of exposure detected by the light emission detection pixel group by executing the first light emission detection operation; the two exposure start timings of the identified unit pixel unit are identified as the two exposure timings, a time difference between the two exposure start timings is calculated as a light emission period of the other distance measuring device, and the exposure duration identified based on the exposure period of the identified unit pixel unit is calculated as a light emission period of the other distance measuring device; It was configured as follows: Ranging device.

3. 2. The distance measuring device according to claim 1, The control device includes: During the interference detection period, controlling a plurality of pixels constituting the emission detection pixel group so as to execute, as the emission detection operation, a second emission detection operation in which the exposure start timing of each unit pixel unit is the same and the exposure period of each unit pixel unit becomes longer in a predetermined order in one of the emission detection pixel groups or each of the plurality of emission detection pixel groups included in the image sensor; using the exposure amount detected by the emission detection pixel group by executing the second emission detection operation, subtracting the exposure amount of the unit pixel portion that has been previously exposed from the exposure amount of each unit pixel portion; and determining the exposure timing at which the unit pixel unit is exposed to the light of the other distance measuring device and the exposure duration during which the unit pixel unit is continuously exposed to the light of the other distance measuring device based on a result of the subtraction. It was configured as follows: Ranging device.

4. 2. The distance measuring device according to claim 1, The unit pixel portion is one pixel. Ranging device.

5. 2. The distance measuring device according to claim 1, The control device includes: The interference detection period and the distance measurement period are alternated. It was configured as follows: Ranging device.

6. 6. The distance measuring device according to claim 5, The control device includes: comparing the detected light emission cycle of the other distance measuring device with the light emission cycle of the own distance measuring device, and judging whether or not interference with the other distance measuring device is occurring based on the comparison result, and if it is judged that interference with the other distance measuring device is occurring, changing the light emission cycle of the next distance measurement period; It was configured as follows: Ranging device.

7. 6. The distance measuring device according to claim 5, The control device includes: comparing the detected light emission cycle of the other distance measuring device with the light emission cycle of the own distance measuring device, and judging whether or not interference with the other distance measuring device is occurring based on the comparison result, and if it is judged that interference with the other distance measuring device is occurring, shifting the light emission timing of the next distance measuring period from the light emission timing of the previous distance measuring period; It was configured as follows: Ranging device.

8. 2. The distance measuring device according to claim 1, The control device includes: The number of times the distance measurement period is executed and the number of times the interference detection period is executed within a predetermined time can be set to any number. It was configured as follows: Ranging device.

9. 2. The distance measuring device according to claim 1, The control device includes: At least one of the shape of the light emission detection pixel group, the position of the light emission detection pixel group, the number of the light emission detection pixel groups, and the number of unit pixel portions constituting the light emission detection pixel group can be changed. It was configured as follows: Ranging device.

10. 2. The distance measuring device according to claim 1, The shape of the luminescence detection pixel group is a row, a radial, a concentric, a spiral, or a square. Ranging device.

11. 2. The distance measuring device according to claim 1, the image sensor includes a plurality of the light emission detection pixel groups, The control device includes: controlling the plurality of light emission detection pixel groups to execute the same light emission detection operation; accumulating the exposure amounts of unit pixel portions that perform the same exposure operation in the plurality of emission detection pixel groups; determining the exposure timing at which the unit pixel unit is exposed to the light of the other distance measuring device and the exposure duration during which the unit pixel unit is continuously exposed to the light of the other distance measuring device based on the integrated exposure amount; It was configured as follows: Ranging device.

12. 2. The distance measuring device according to claim 1, The control device includes: when no light emission from the other distance measuring device is detected for a predetermined period of time, the number of times the distance measurement period is executed and the number of times the interference detection period is executed within a predetermined time are set so that the number of times the interference detection period is executed is less than the number of times the distance measurement period is executed, or the execution of the interference detection period is stopped. It was configured as follows: Ranging device.

13. 2. The distance measuring device according to claim 1, The control device includes: The control state is configured to execute either a first control state in which the interference detection period and the distance measurement period are executed, or a second control state in which only the distance measurement period is executed, The control device can switch between the first control state and the second control state. It was configured as follows: Ranging device.

14. 2. The distance measuring device according to claim 1, An acceleration sensor is provided for detecting acceleration, The control device includes: determining whether the distance measuring device is moving based on the acceleration acquired by the acceleration sensor; When the distance measuring device is not moving, the frequency of execution of the interference detection period is made less than the frequency of execution of the distance measurement period, or execution of the interference detection period is stopped; When the distance measuring device is moving, the frequency of execution of the interference detection period is set to be higher than the frequency of execution of the distance measurement period. It was configured as follows: Ranging device.

15. A distance measuring method using a distance measuring device that measures a distance based on a flight time until a measurement light is irradiated toward a measurement object and reflected by the measurement object and returns, The distance measuring device is an irradiation unit that irradiates the measurement object with the measurement light; an image sensor including a plurality of pixels whose exposure and non-exposure are controlled; a control device that controls the irradiation unit and the image sensor and obtains an exposure amount of a pixel from the image sensor; Equipped with By the control device, a distance measurement period in which the irradiation unit emits the measurement light, the plurality of pixels perform exposure to light reflected by the measurement object from the measurement light, and the distance is calculated based on the amount of exposure; and an interference detection period in which the irradiation unit stops emitting the measurement light, and the plurality of pixels perform exposure, During the interference detection period, a light emission detection pixel group including a plurality of unit pixel portions each composed of one pixel or a plurality of pixels controlled to perform the same exposure operation, the unit pixel portion being composed of at least a portion of the plurality of pixels of the image sensor, the light emission detection pixel group being controlled to perform the same exposure operation, the light emission detection pixel group being controlled so that, in the one light emission detection pixel group or each of the plurality of light emission detection pixel groups included in the image sensor, any of the exposure start timings and exposure periods of each unit pixel portion are different from each other to perform light emission detection operations; identifying an exposure timing at which the unit pixel unit is exposed to light from another distance measuring device and an exposure duration at which the unit pixel unit is continuously exposed to light from the other distance measuring device based on the exposure amount detected by the light emission detection pixel group by executing the light emission detection operation; calculating a light emission period of the other distance measuring device based on the exposure timing, and calculating a light emission period of the other distance measuring device based on the exposure duration; Distance measurement method.

Images