Distance measuring device

Abstract

To provide a distance measuring device that can improve distance measurement performance while achieving eye-safety.SOLUTION: A distance measuring device has: a light-emitting device array in which a plurality of light-emitting devices each having a variable light-emitting power are two-dimensionally arranged; a thinning-out control unit that performs thinning-out light-emission control so that a part of the light-emitting devices, of the plurality of light-emitting devices, are turned on, and the other part of the light-emitting devices are not turned on; and a power control unit that controls the light-emitting power of each of the plurality of light-emitting devices so that the light-emitting power per unit area does not exceed a threshold, on the basis of a first thinning-out rate indicating the ratio of the light-emitting devices that are not turned on to all the plurality of light-emitting devices.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a distance measuring device that measures distance using LiDAR (Light Detection And Ranging) technology. The distance measuring device of Patent Document 1 includes a surface light emitting element array that includes multiple surface light emitting elements, and irradiates a target with light. Each of the multiple surface light emitting elements of Patent Document 1 can be individually switched on or off. The distance measuring device of Patent Document 1 controls the combination of surface light emitting elements that are turned on so that the total amount of light energy that may be incident on the human eye is below a preset threshold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-116280 Summary of the Invention [Problem to be solved by the invention]

[0004] In a distance measuring device that measures distance by irradiating light as in Patent Document 1, there is a demand for both eye safety and improved distance measurement performance.

[0005] Therefore, an object of the present invention is to provide a distance measuring device that can improve distance measurement performance while realizing eye safety. [Means for solving the problem]

[0006] According to one disclosure of this specification, there is provided a distance measuring device characterized by having: a light-emitting element array in which a plurality of light-emitting elements, each of which has a variable light-emitting power, is arranged two-dimensionally; a thinning control unit that performs thinning-out light emission control so that some of the plurality of light-emitting elements emit light and some of the light-emitting elements do not emit light; and a power control unit that controls the light-emitting power of each of the plurality of light-emitting elements based on a first thinning rate that indicates the proportion of light-emitting elements among the plurality of light-emitting elements that do not emit light, so that the light-emitting power per unit area does not exceed a threshold value.

[0007] According to one disclosure of this specification, there is provided a distance measuring device comprising: an array of light-emitting elements in which a plurality of light-emitting elements, each with a variable light-emitting power, is arranged two-dimensionally; a thinning control unit that performs thinning-out light emission control so that some of the plurality of light-emitting elements emit light and some of the light-emitting elements do not emit light; and a power control unit that controls the light-emitting power of each of the plurality of light-emitting elements, wherein the thinning control unit sets a first thinning rate that indicates the proportion of light-emitting elements among the plurality of light-emitting elements that do not emit light, based on the light-emitting power of each of the plurality of light-emitting elements, so that the light-emitting power per unit area does not exceed a threshold value. [Effects of the Invention]

[0008] According to the present invention, a distance measuring device is provided that can improve distance measurement performance while realizing eye safety. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a hardware block diagram showing an example of the schematic configuration of a distance measuring device according to a first embodiment. [Figure 2] 1 is a functional block diagram showing an example of a schematic configuration of a distance measuring device according to a first embodiment. [Figure 3] 2 is a diagram showing an outline of the operation of the distance measuring device according to the first embodiment in one distance measuring period. FIG. [Figure 4] 10 is a graph visually showing the frequency distribution of light reception count values ​​according to the first embodiment. [Figure 5]5A and 5B are schematic diagrams illustrating thinning-out light emission control of the light-emitting element array according to the first embodiment. [Figure 6] 4 is a flowchart illustrating the operation of the distance measuring device according to the first embodiment. [Figure 7] 10 is a flowchart illustrating the operation of the distance measuring device according to the second embodiment. [Figure 8] 10A and 10B are schematic diagrams showing thinning-out light emission control of a light-emitting element array and thinning-out light reception control of a light-receiving element array according to a third embodiment. [Figure 9] 10A and 10B are schematic diagrams showing thinning-out light emission control of a light-emitting element array and thinning-out light reception control of a light-receiving element array according to a fourth embodiment. [Figure 10] FIG. 10 is a schematic diagram of a device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0011] [First embodiment] 1 is a hardware block diagram showing an example of the schematic configuration of a distance measuring device 1 according to this embodiment. The distance measuring device 1 has a light emitting device 2, a signal processing circuit 3, and a light receiving device 4. Note that the configuration of the distance measuring device 1 shown in this embodiment is an example, and is not limited to the configuration shown in the figure.

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

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

[0014] The light received by the light receiving device 4 includes ambient light such as sunlight in addition to the reflected light from the object X. Therefore, the distance measuring device 1 performs distance measurement with reduced influence of ambient light by repeatedly performing a measurement operation to identify the period in which light is incident among a plurality of periods (bin periods) and determining that the reflected light is incident during the period when the light intensity is at its peak.

[0015] The light emitting device 2 is a device such as a semiconductor laser that emits light to the outside of the distance measuring device 1. This semiconductor laser may be, for example, a vertical cavity surface emitting laser (VCSEL).

[0016] The signal processing circuit 3 may include a control circuit, a counter circuit, a processor that performs arithmetic processing of digital signals, a memory that stores digital signals, etc. The memory may be, for example, a semiconductor memory.

[0017] The light receiving device 4 generates a pulse signal including pulses based on incident light and generates a light receiving count value by counting the pulse signal. The light receiving device 4 is, for example, a photoelectric conversion device including an avalanche photodiode as a photoelectric conversion element. In this case, when one photon is incident on the avalanche photodiode and an electric charge is generated, one pulse is generated by avalanche multiplication. However, the light receiving device 4 may also be one that uses, for example, a photoelectric conversion element that uses another photodiode.

[0018] 2 is a functional block diagram showing an example of the schematic configuration of a distance measuring device 1 according to this embodiment. The distance measuring device 1 has a light emitting element array 21, a light receiving element array 41, a thinning control unit 31, a laser power control unit 32, a time counting unit 33, a frequency distribution generating unit 34, a frequency distribution holding unit 35, and an output unit 36. The light emitting element array 21 and the light receiving element array 41 correspond to the light emitting device 2 and the light receiving device 4 in FIG. 1, respectively. The thinning control unit 31, the laser power control unit 32, the time counting unit 33, the frequency distribution generating unit 34, the frequency distribution holding unit 35, and the output unit 36 ​​correspond to the signal processing circuit 3 in FIG. 1.

[0019] The light-emitting element array 21 has a plurality of light-emitting elements 210 arranged two-dimensionally to form a plurality of rows and a plurality of columns. Each of the plurality of light-emitting elements 210 emits light toward the object X. Each of the plurality of light-emitting elements 210 is preferably a laser light source that emits laser light with high linearity. The laser light source may be, for example, a surface-emitting laser. Furthermore, the light-emitting power of each of the plurality of light-emitting elements 210 is variable, and the light-emitting power is controlled by a laser power control unit 32. The light emitted from the light-emitting element array 21 is reflected by the object X and then enters the light-receiving element array 41. In the following description, each of the plurality of light-emitting elements 210 is assumed to be a laser element that emits laser light, but is not limited to this.

[0020] The light receiving element array 41 has a plurality of light receiving elements 410 arranged two-dimensionally to form a plurality of rows and a plurality of columns. Each of the plurality of light receiving elements 410 generates a pulse signal including pulses based on incident light, and generates a light receiving count value by counting the pulse signals. The light receiving element 410 is, for example, a SPAD (Single Photon Avalanche Diode) including an avalanche photodiode, but is not limited to this.

[0021] The thinning control unit 31 performs thinning-out light emission control for the light-emitting element array 21 and thinning-out light reception control for the light-receiving element array 41. The thinning-out light emission control is an operation of controlling each of the plurality of light-emitting elements 210 included in the light-emitting element array 21 so that some of the light-emitting elements 210 emit light and some of the light-receiving elements 410 do not emit light. The thinning-out light reception control is an operation of controlling each of the plurality of light-emitting elements 210 included in the light-receiving element array 410 so that some of the light-receiving elements 410 are enabled and some of the light-receiving elements 410 are disabled. The ratio of the light-emitting elements 210 that do not emit light to the total number of the plurality of light-emitting elements 210 is referred to as the thinning rate (first thinning rate) of the light-emitting element array 21. The ratio of the light-receiving elements 410 that are disabled to the total number of the light-receiving elements 410 is referred to as the thinning rate (second thinning rate) of the light-receiving element array 410. The thinning control unit 31 outputs information indicating the thinning rate of the light-emitting element array 21 to the laser power control unit 32. Note that the light-receiving elements 410 can be disabled, for example, by stopping counting pulse signals in the light-receiving elements 410. Alternatively, if the light receiving element 410 has a function of recharging the potential of the avalanche photodiode, the light receiving element 410 may be disabled by stopping the supply of a recharging pulse or clock signal.

[0022] The thinning control unit 31 also controls the start timing of time counting in the time counting unit 33 in synchronization with the operation timing of the light emitting element array 21 and the light receiving element array 41. The time counting unit 33 outputs the time count value to the frequency distribution generating unit 34.

[0023] The laser power control unit 32 controls the laser power of the light-emitting elements 210 based on the information on the thinning rate of the light-emitting element array 21 acquired from the thinning control unit 31. Here, the laser power is the energy of the laser light emitted from the light-emitting element 210 per unit time. Based on the information on the thinning rate of the light-emitting element array 21, the laser power control unit 32 controls the laser power of each of the plurality of light-emitting elements 210 so that the laser power per unit area does not exceed a predetermined threshold. The laser power control unit 32 controls the laser power by, for example, controlling the power supplied to each of the plurality of light-emitting elements 210.

[0024] The frequency distribution generating unit 34 receives the light-receiving count values ​​output from each of the plurality of light-receiving elements 410 and the time count values ​​output from the time counting unit 33. The frequency distribution generating unit 34 accumulates the light-receiving count values ​​at predetermined time intervals to generate a frequency distribution in which the time intervals are associated with the light-receiving count values. The frequency distribution holding unit 35 holds the frequency distribution generated by the frequency distribution generating unit 34. The frequency distribution holding unit 35 has a storage capacity for storing the frequency distribution for each of the plurality of light-receiving elements 410.

[0025] The frequency distribution held in the frequency distribution holding unit 35 can be output as is to the outside as distance information via the output unit 36. In this case, an external signal processing device performs processing to calculate the distance from the distance measuring device 1 to the object X based on the peaks of the frequency distribution. The frequency distribution held in the frequency distribution holding unit 35 may also be converted into information indicating distance by the output unit 36 ​​and output to the outside. In this case, the output unit 36 ​​performs processing to determine the peaks of the frequency distribution and outputs information indicating the time interval between the peaks to the outside as distance information from the distance measuring device 1 to the object X in a predetermined output format. In this case, the output unit 36 ​​also functions as a distance calculation unit.

[0026] 3 is a diagram showing an outline of the operation of the distance measuring device 1 according to this embodiment in one distance measurement period. The "distance measurement period" in FIG. 3 shows multiple frame periods FL1, FL2, ... FL3 included in one distance measurement period. Frame period FL1 indicates the first frame period in one distance measurement period, frame period FL2 indicates the second frame period in one distance measurement period, and frame period FL3 indicates the final frame period in one distance measurement period. A frame period is a period during which the distance measuring device 1 performs one distance measurement and outputs the distance measurement result from the distance measuring device 1 to the object X to the outside once as distance information.

[0027] The "frame period" in FIG. 3 shows multiple shots SH1, SH2, ... SH3 and peak determination POUT included in frame period FL1. A shot is a period during which the light-emitting element array 21 emits light and the frequency distribution is updated by a light-receiving pulse PL2 based on this light emission. Shot SH1 indicates the first shot in frame period FL1. Shot SH2 indicates the second shot in frame period FL1. Shot SH3 indicates the final shot in frame period FL1. Peak determination POUT indicates a period during which a distance measurement result is determined and output based on a peak obtained by accumulating signals from multiple shots. While FIG. 3 shows an example in which peak determination is performed once at the end of a frame period, peak determination may be performed after processing each shot, or after processing a predetermined number of shots.

[0028] The "shot" in FIG. 3 shows multiple bins BN1, BN2, ... BN3 included in shot SH1. A "bin" indicates one time interval (bin period) during which a series of pulse counts are performed. Bin BN1 indicates the first bin in shot SH1. Bin BN2 indicates the second bin in shot SH1. Bin BN3 indicates the last bin in shot SH1. Note that peak determination may be performed after each bin period has elapsed, or may be performed every time a predetermined number of bin periods have elapsed.

[0029] "Time count" in FIG. 3 shows a schematic representation of the time change of the time count value generated by the time counting unit 33. As shown in FIG. 3, the time counting unit 33 counts up the time count value for each bin time interval as time passes. Therefore, the time count value is a parameter indicating the bin number. The time count pulse PL1 in FIG. 3 shows a pulse for counting up the time count value.

[0030] "Light reception count" in Figure 3 schematically shows a light reception pulse PL2 based on an incident photon in bin BN1. As shown in Figure 3, when the light reception pulse PL2 rises, the light reception count value counts up by 1. As a result, the number of photons detected within the bin period is acquired as the light reception count value. When one bin period elapses and the next bin period begins, the light reception count value is reset to zero.

[0031] 4(a) to 4(d) are graphs visually showing the frequency distribution of the received light count values ​​generated by the frequency distribution generating unit 34. In this specification, the frequency distribution is information in which the received light count values ​​are associated with each time interval, and does not necessarily have to be visually displayed. FIGS. 4(a), 4(b), and 4(c) are examples of the frequency distribution of the received light count values ​​(corresponding to the number of incident photons) in the first, second, and third shots, respectively. FIG. 4(d) is an example of a frequency distribution obtained by accumulating the received light count values ​​of all shots. The horizontal axis indicates the elapsed time from light emission. One section of the frequency distribution corresponds to one bin period during which photons are detected. The vertical axis indicates the received light count value acquired in each bin period.

[0032] As shown in FIG. 4(a), in the first shot, photons are incident in five bin periods. In the first shot, the sixth bin BN11 has the largest light-receiving count value, so bin BN11 is the peak. As shown in FIG. 4(b), in the second shot, photons are incident in four bin periods. In the second shot, the third bin BN12 and the fifth bin BN13 have the largest light-receiving count values, so bins BN12 and BN13 are the peaks. As shown in FIG. 4(c), in the third shot, photons are incident in four bin periods. In the third shot, the sixth bin BN14 has the largest light-receiving count value, so bin BN14 is the peak. Thus, in the examples of FIGS. 4(a) to 4(c), the number and time of incident photons differ in each shot. These frequency distributions may include light-receiving count values ​​due not only to reflected light from object X but also to ambient light other than reflected light. Therefore, as shown in Fig. 4(a) to Fig. 4(c), different bins may be detected as peaks for each shot.

[0033] As shown in Figure 4(d), in the frequency distribution obtained by accumulating the light-receiving count values ​​of all shots, the sixth bin BN15 has the largest number of photons, and therefore bin BN15 is the peak. In peak determination POUT in Figure 3, the peak of the accumulated frequency distribution is determined, and time information of the bin corresponding to the peak is output. This time information indicates the time of flight of light emitted from the light-emitting element array 21 and reflected by the object X, and can be used to calculate the distance between the distance measuring device 1 and the object X.

[0034] By accumulating the light reception count values ​​of multiple shots, even if the light reception count values ​​may be due to ambient light, it is possible to more accurately detect bins that are likely to include light reception count values ​​due to reflected light from the object X. Therefore, even if the light emitted from the light-emitting element array 21 is weak, it is possible to perform distance measurement with high accuracy by repeating multiple shots and employing a process of accumulating the light reception count values ​​of the multiple shots.

[0035] The relationship between thinning-out light emission control and eye safety in the light-emitting element array 21 will be described with reference to FIGS. 5(a), 5(b), and 5(c). FIGS. 5(a), 5(b), and 5(c) are schematic diagrams illustrating thinning-out light emission control in the light-emitting element array 21 according to this embodiment. FIGS. 5(a), 5(b), and 5(c) show the light-emitting states and aperture ranges of the multiple light-emitting elements 210 in the light-emitting element array 21. The hatched light-emitting elements 210a represent light-emitting elements 210 in an emitting state, while the unhatched light-emitting elements 210b represent light-emitting elements 210 in a non-emitting state. The aperture range R1 is a reference range used to determine the intensity per unit area of ​​a laser in the eye safety standard for laser products, and corresponds to the area of ​​the human eye. While this reference range may be circular in practice, the aperture range R1 is depicted as a square in FIG. 5 for simplicity.

[0036] 5(a) schematically illustrates a state in which thinning-out light emission control of the light-emitting element array 21 is not performed, that is, a state in which the entire surface of the light-emitting element array 21 emits light. As shown in FIG. 5(a), all of the 16 light-emitting elements 210a within the opening range R1 are in a light-emitting state.

[0037] FIG. 5(b) schematically illustrates the arrangement of the light-emitting elements 210a and 210b when thinning-out light emission control of the light-emitting element array 21 is performed at a thinning rate of 1 / 2. In the example of FIG. 5(b), every other light-emitting element 210a in the emitting state and every other light-emitting element 210b in the non-emitting state are arranged in each row and each column. That is, the light-emitting elements 210a and the non-emitting light-emitting elements 210b form a checkered pattern. As shown in FIG. 5(b), within the opening range R1, eight of the 16 light-emitting elements 210a are in the emitting state, and the remaining eight light-emitting elements 210b are in the non-emitting state. The arrangement of the light-emitting elements 210a and the non-emitting light-emitting elements 210b can be changed as appropriate depending on the thinning rate. That is, a plurality of light-emitting elements 210a in the emitting state may be arranged consecutively, or a plurality of non-emitting light-emitting elements 210b may be arranged consecutively. The thinning-out light receiving control in the light receiving element array 41 can also be performed in the same manner as in FIG. 5(b) according to the thinning out rate.

[0038] Fig. 5(c) shows a schematic diagram of the arrangement of the light-emitting elements 210a and 210b when control is performed to narrow the light-emitting range so that the light-emitting elements 210a in the light-emitting state are concentrated in the opening range R1. In the example of Fig. 5(c), the light-emitting elements 210a in the light-emitting state are arranged within the opening range R1, and the light-emitting elements 210b in the non-light-emitting state are arranged outside the opening range R1.

[0039] Here, for example, the laser power for one light-emitting element is assumed to be α (mW). In this case, the laser power per unit area is calculated by (laser power for one light-emitting element α) × (number of light-emitting elements per unit area). Therefore, the laser power per area of ​​the aperture range R1 is calculated by (laser power for one light-emitting element α) × (number of light-emitting elements within the aperture range R1). Meanwhile, the laser power threshold that satisfies the eye safety regulations is assumed to be 20 times α, i.e., 20α.

[0040] In the situation shown in FIG. 5(a), the number of light-emitting elements in the aperture range R1 is 16α, which is below the threshold. On the other hand, in the situation shown in FIG. 5(b), the number of light-emitting elements in the aperture range R1 is 8 due to thinning at a thinning rate of 1 / 2. Therefore, the laser power in the aperture range R1 is 8α, which is also below the threshold. Furthermore, even if the laser power per light-emitting element in the situation shown in FIG. 5(b) is doubled, i.e., even if the laser power per light-emitting element is 2α, the laser power in the aperture range R1 is still 16α, which is maintained below the threshold. Therefore, by performing thinning-out light emission control, it is possible to control the laser power per area of ​​the aperture range R1 so that it does not exceed the threshold, even if the laser power per light-emitting element is increased.

[0041] Furthermore, because the number of light-emitting elements within the aperture range R1 in the situation shown in Figure 5(c) is 16, the laser power within the aperture range R1 is 16α, the same as in Figure 5(a). Although this is below the threshold, doubling the laser power per light-emitting element would cause the laser power within the aperture range R1 to exceed the threshold. Therefore, to double the laser power per light-emitting element while still satisfying the eye safety regulations in the situation shown in Figure 5(c), the light-emitting area within the aperture range R1 must be reduced by more than half. This method reduces the complexity of the light-emitting area setting because it is constrained by the requirement to limit the light-emitting area to less than half of the aperture range R1. In contrast, thinning-out light-emitting control, as shown in Figure 5(b), reduces the spatial resolution of the distance measurement results, but is effective in situations where rough distance information within the light-emitting area is desired.

[0042] For these reasons, the thinning-out light emission control shown in Figure 5(b) is suitable from the viewpoints of eye safety, distance measurement range, and laser power. Furthermore, increasing the laser power also increases the intensity of the reflected light, making it possible to detect peaks even with a reduced number of shots per frame period. This allows the frame rate to be increased, making the thinning-out light emission control shown in Figure 5(b) also suitable from the viewpoint of frame rate.

[0043] Fig. 6 is a flowchart illustrating the operation of the distance measuring device 1 according to this embodiment. Fig. 6 shows the operation from the start to the end of the distance measuring period. In the example of Fig. 6, it is assumed that the peak determination POUT in Fig. 3 is performed not only after processing the final shot, but also after processing each shot and after the completion of a predetermined bin period.

[0044] In step S11, the thinning control unit 31 sets a thinning rate N1 for the light-emitting element array 21 and a thinning rate N2 for the light-receiving element array 41. The light-emitting elements 210 that will emit light and the light-emitting elements 210 that will not emit light are determined in the light-emitting element array 21 according to the thinning rate N1 set by the thinning control unit 31. In addition, the light-receiving elements 410 that will be enabled and the light-receiving elements 410 that will be disabled are determined in the light-receiving element array 41.

[0045] Since step S11 is a step for setting the initial conditions for distance measurement, the thinning rates N1 and N2 may be set to, for example, zero (no thinning). However, in a situation where it is known in advance that the distance from the distance measuring device 1 to the object X is short, the thinning rates N1 and N2 may be set to a value greater than zero, such as 1 / 2.

[0046] Furthermore, in step S11, the laser power control unit 32 sets a laser power α per each light-emitting element 210 and a threshold value β of the laser power per unit area. The laser power α per each light-emitting element 210 can be set based on a thinning rate N1 so that the laser power per unit area does not exceed the threshold value β. The thinning control unit 31 determines the number of shots γ per frame period based on the thinning rates N1, N2, and the laser power α. The setting of the number of shots γ can be determined based on a table that specifies the correspondence between the ranges of the thinning rates N1, N2, and the laser power α and the number of shots γ.

[0047] The parameters set in step S11 can be set appropriately depending on the state of the object X, the distance measurement scene, etc. The above description is an example in which the number of shots γ is determined from the thinning rates N1, N2 and the laser power α, but the number of shots γ may be determined first, and the thinning rates N1, N2 or the laser power α may be determined based on the number of shots γ. For example, in a scene in which the object X is moving at high speed, it is desirable to improve the frame rate, so the number of shots γ may be set first. Furthermore, in an environment in which strong sunlight is incident on the light-receiving element array 41, the influence of ambient light may be reduced by setting the laser power α first.

[0048] Furthermore, it is desirable that the laser power threshold β be set to satisfy radiation safety standards for laser products. Specifically, the threshold β can be set to satisfy Class 1 of IEC 60825-1 of the International Electrotechnical Commission (IEC). Alternatively, the threshold β can be set to satisfy Class 1 of JIS C 6802 of the Japanese Industrial Standards (JIS). Alternatively, the threshold β can be set to satisfy Class 1 of EN 60825-1 of the European Standards. As described above, the laser power threshold β can be set to satisfy at least one of various radiation safety standards for laser products.

[0049] In step S12, the light-emitting element array 21 emits light into the distance measurement range. At the same time, the time counting unit 33 starts counting time. This starts the signal acquisition process for one shot. The thinning control unit 31 controls the light emission of the light-emitting element array 21 and the start of the time counting by the time counting unit 33 so that they are synchronized. This makes it possible to count the elapsed time from the light emission. The light-receiving element array 41 receives light including reflected light from the object X. Each of the multiple light-receiving elements 410 of the light-receiving element array 41 converts the incident light into a pulse signal by photoelectric conversion. The rising edge of this pulse indicates that a photon has entered the photoelectric conversion element.

[0050] In step S13, if light receiving element 410 detects the rising edge of the pulse (YES in step S13), the process proceeds to step S14. If light receiving element 410 does not detect the rising edge of the pulse (NO in step S13), the process proceeds to step S15.

[0051] In step S14, the frequency distribution generating unit 34 increments the light-receiving count value corresponding to the light-receiving element 410 in which the rising edge of the pulse was detected by 1. Then, the process proceeds to step S15.

[0052] In step S15, the distance measuring device 1 waits until the time count value in the time counting unit 33 is incremented by one. The time counting by the time counting unit 33 starts from zero. The time counting can be performed, for example, by counting up a clock signal that oscillates at a high speed and a constant period, generated using a ring oscillator. If the period of the clock signal is 0.1 microseconds, when the time count value increases from 0 to 10 by the time counting, it can be detected that the elapsed time is 1 microsecond. Note that in this embodiment, as shown in FIG. 3, it is assumed that the clock signal for time counting is set so that the period of the time count is sufficiently shorter than the frequency of light reception counts.

[0053] In step S16, if the current time indicated by the current time count value is before the end of the bin period being processed (NO in step S16), the process proceeds to step S13 and pulse detection continues. If the current time is after the bin period being processed (YES in step S16), the process proceeds to step S17 and processing for one clock period ends. In this way, the light receiving operation for one clock period is performed by the loop from step S13 to step S16.

[0054] In step S17, if a peak cannot be determined before the predetermined bin period in one shot is completed (NO in step S17), the process proceeds to step S18. If a peak can be determined before the predetermined bin period in one shot is completed or if the predetermined bin period in one shot is completed (YES in step S17), the process proceeds to step S19.

[0055] In step S18, the thinning control unit 31 changes the thinning rate N1 of the light-emitting element array 21 and the thinning rate N2 of the light-receiving element array 41. The thinning control unit 31 outputs information about the changed thinning rate N1 to the laser power control unit 32. The laser power control unit 32 changes the laser power α per light-emitting element 210 based on the thinning rate N1. The laser power α can be set based on the changed thinning rate N1 so that the laser power per unit area does not exceed the threshold value β. For example, if the thinning rate N1 is changed to a larger value and the proportion of light-emitting elements 210 in a non-light-emitting state increases, the laser power control unit 32 increases the laser power α so that the laser power per unit area does not exceed the threshold value β. Then, the process proceeds to step S17. Note that one or more predetermined bin periods in the process of step S17 are specified in advance, and the processes of steps S17 and S18 can be repeated the same number of times as the specified bin periods.

[0056] In step S19, if the current time indicated by the current time count value is before the end time of the final bin period of the shot being processed (NO in step S19), the process proceeds to step S20. In step S20, the distance measuring device 1 performs a switching process to transition to the next bin period. This switching process may include resetting the light reception count value. Thereafter, the process proceeds to step S13, where pulse detection continues. If the current time is after the final bin period of the shot being processed (YES in step S19), the process proceeds to step S21, where the process for one bin period ends. In this way, the light reception operation for one shot is performed by the loop from step S13 to step S19.

[0057] In step S21, if a peak cannot be determined from the frequency distribution after the completion of the final bin period (NO in step S21), the process proceeds to step S22. If a peak can be determined from the frequency distribution after the completion of the final bin period (YES in step S21), the process proceeds to step S23.

[0058] In step S22, the thinning-out control unit 31 and the laser power control unit 32 change the thinning rates N1 and N2 and the laser power α by the same process as in step S18. Note that in the process of step S22, the number of shots γ in one frame period may also be changed. For example, by reducing the number of shots γ, the processing time in the middle of one frame period can be shortened and the frame rate can be improved.

[0059] In step S23, if the current time indicated by the current time count value is before the completion time of the final shot (NO in step S23), the process proceeds to step S12, where the next shot is processed. If the current time indicated by the current time count value is after the completion time of the final shot (YES in step S23), the process proceeds to step S24, where the processing of one shot is completed. In this way, the light emitting operation and light receiving operation of one shot are performed by the loop from step S12 to step S23.

[0060] In step S24, the output unit 36 ​​outputs the frequency distribution or peak information stored in the frequency distribution storage unit 35 to the outside of the distance measuring device 1.

[0061] In step S25, if a peak cannot be determined from the frequency distribution after the completion of the final shot (NO in step S25), the process proceeds to step S26. If a peak can be determined from the frequency distribution after the completion of the final shot (YES in step S25), the process proceeds to step S27.

[0062] In step S26, the thinning-out control unit 31 and the laser power control unit 32 change the thinning rates N1 and N2 and the laser power α by the same process as in step S18. Note that in the process of step S26, the number of shots γ per frame period may also be changed. For example, by reducing the number of shots γ, the processing time can be shortened and the frame rate can be improved from the next frame period.

[0063] In step S27, the distance measuring device 1 determines whether or not to end distance measuring. If it is determined that distance measuring should be ended (YES in step S27), this process ends. If it is determined that distance measuring should not be ended (NO in step S27), the process proceeds to step S12, the light reception count value is reset, and distance measuring for the next frame period is started. This determination may be based on, for example, a control signal from the equipment in which the distance measuring device 1 is installed.

[0064] Note that the parameter change processes of steps S17 and S18, the parameter change processes of steps S21 and S22, and the parameter change processes of S25 and S26 are merely examples of timings when the parameter change processes may be performed, and are not essential. For example, the parameter change processes of steps S17 and S18, the parameter change processes of steps S21 and S22, and the parameter change processes of S25 and S26 may be modified so that any one of them is performed.

[0065] Also, in the explanation of Figure 6, for simplicity, the explanation focuses on one light-emitting element 210 and one light-receiving element 410, but processing can be performed in parallel on multiple light-emitting elements 210 and multiple light-receiving elements 410.

[0066] According to this embodiment, eye safety is ensured by the thinning-out light emission control of the light-emitting element array 21. Furthermore, during thinning-out light emission control, the laser power α per light-emitting element 210 can be controlled to a sufficient value according to the thinning-out rate N1. This allows the emitted light to reach a longer distance than when thinning-out light emission control is performed with the laser power α held constant, thereby expanding the range of distances that can be measured. Furthermore, compared to when thinning-out light emission control is performed with the laser power α held constant, the probability of receiving reflected light increases, allowing peak determination to be performed earlier and improving the frame rate. Therefore, this embodiment provides a distance measuring device that can improve distance measurement performance while ensuring eye safety.

[0067] In this embodiment, a distance measurement method in which time is measured by the time count unit 33 has been exemplified, but the distance measurement method is not limited to this. For example, a distance measurement method may be applied in which the exposure period is controlled so that the light receiving element receives reflected light only during the time interval in which light reflected by an object at a predetermined distance is incident on the light receiving element, and this exposure period is shifted to perform measurements multiple times to generate a frequency distribution.

[0068] The thinning rate N1 of the light-emitting element array 21 and the thinning rate N2 of the light-receiving element array 41 may be the same, for example. In this case, even when thinning-out light emission control and thinning-out light reception control are performed, the correspondence between the light-emitting elements 210 and the light-receiving elements 410 can be maintained, and the processing procedure can be simplified.

[0069] On the other hand, the thinning rate N1 of the light-emitting element array 21 and the thinning rate N2 of the light-receiving element array 41 may be different. In this case, thinning-out light emission control and thinning-out light reception control can be performed with a high degree of freedom. However, when the thinning rate N1 of the light-emitting element array 21 and the thinning rate N2 of the light-receiving element array 41 are different, the projection optical system is controlled to adjust the projection position and projection range so that the light-emitting range of one light-emitting element 210 encompasses the light-receiving range of one or more light-receiving elements.

[0070] Furthermore, the thinning-out light-receiving control of the light-receiving element array 41 is not essential. For example, a control method may be applied in which the light-emitting element array 21 is subjected to thinning-out light-receiving control at a predetermined thinning rate N1, the laser power α is increased, and thinning-out light-receiving control is not performed on the light-receiving element array 41. In this case, the measurable distance range can be expanded without reducing the spatial resolution of the light-receiving element array 41.

[0071] [Second embodiment] A modified example of the method for setting the thinning rates N1 and N2 and the laser power α described in the first embodiment will be described as the second embodiment. FIG. 7 is a flowchart illustrating the operation of the distance measuring device 1 according to this embodiment. In this embodiment, steps S18, S22, and S26 in the first embodiment are replaced with steps S18a, S22a, and S26a, respectively. Also, in this embodiment, the order in which parameters are determined in the initial setting of step S11 differs from that of the first embodiment. In this embodiment, descriptions of elements common to the first embodiment may be omitted or simplified.

[0072] In step S11, the laser power control unit 32 sets a laser power α per light-emitting element 210 and a threshold value β of laser power per unit area. Then, the thinning control unit 31 sets a thinning rate N1 for the light-emitting element array 21 and a thinning rate N2 for the light-receiving element array 41. Here, the thinning rate N1 for the light-emitting element array 21 can be set based on the laser power α per light-emitting element 210 so that the laser power per unit area does not exceed the threshold value β.

[0073] In step S18a, the laser power control unit 32 changes the laser power α per light-emitting element 210. The laser power control unit 32 outputs information about the changed laser power α to the thinning control unit 31. The thinning control unit 31 changes the thinning rate N1 of the light-emitting element array 21 and the thinning rate N2 of the light-receiving element array 41 based on the changed laser power α. The thinning rate N1 can be set based on the changed laser power α so that the laser power per unit area does not exceed the threshold value β. For example, if the laser power α is changed to a larger value, the thinning control unit 31 changes the thinning rate N1 of the light-emitting element array 21 to a larger value, increasing the proportion of light-emitting elements 210 that are not emitting light, and preventing the laser power per unit area from exceeding the threshold value β.

[0074] In steps S22a and S26a, the thinning-out control unit 31 and the laser power control unit 32 change the thinning rates N1 and N2 and the laser power α by the same process as in step S18a. In the processes of steps S22a and S26a, the number of shots γ per frame period may also be changed. For example, by reducing the number of shots γ, the processing time can be shortened and the frame rate can be improved.

[0075] In this embodiment, as in the first embodiment, a distance measuring device that can improve distance measurement performance while realizing eye safety is provided.

[0076] [Third embodiment] In this embodiment, a case will be described in which the light emitting range of one light emitting element 211 is larger than the light receiving range of one light receiving element 411. In this embodiment, the description of elements common to the first and second embodiments may be omitted or simplified.

[0077] 8(a), 8(c), 8(e), and 8(g) are schematic diagrams showing the thinning-out light-emitting control of the light-emitting element array 21 according to this embodiment. 8(b), 8(d), 8(f), and 8(h) are schematic diagrams showing the thinning-out light-receiving control of the light-receiving element array 41.

[0078] 8(a) and 8(b) each schematically show the light-emitting range of the light-emitting element 211 of the light-emitting element array 21 and the light-receiving range of the light-receiving element 411 of the light-receiving element array 41. Each box in FIG. 8(a) represents the light-emitting range of one light-emitting element 211. Each box in FIG. 8(b) represents the light-receiving range of one light-receiving element 411. As shown in FIGS. 8(a) and 8(b), the light-emitting range of one light-emitting element 211 is wider than the light-receiving range of the light-receiving element 411. In the examples of FIGS. 8(a) to 8(f), the area of ​​the light-emitting range of one light-emitting element 211 is four times the area of ​​the light-receiving range of one light-receiving element 411, but this is not limited to this. For example, the area of ​​the light-emitting range of one light-emitting element 211 may be an integer multiple of the area of ​​the light-receiving range of one light-receiving element 411. That is, the light emitting range of one light emitting element 211 can correspond to the light receiving ranges of m light receiving elements 411 (m is an integer of 2 or more).

[0079] In Figures 8(c), 8(e), and 8(g), the hatched light-emitting elements 211a and 211c indicate light-emitting elements 211 in an emitting state, and the unhatched light-emitting element 211b indicates a light-emitting element 211 in a non-emitting state. In Figures 8(d), 8(f), and 8(h), the hatched light-receiving elements 411a, 411d to 411i indicate enabled light-receiving elements 411. Furthermore, the unhatched light-receiving elements 411b and 411c indicate disabled light-receiving elements 411.

[0080] Fig. 8(c) shows a schematic arrangement of the light-emitting elements 211a and 211b when thinning-out light emission control of the light-emitting element array 21 is performed at a thinning rate of 1 / 2. In the example of Fig. 8(c), every other light-emitting element 211a in an emitting state and every other light-emitting element 211b in a non-emitting state are arranged in each row and each column.

[0081] Fig. 8(d) shows a schematic diagram of the arrangement of the light receiving elements 411a, 411b, 411c, and 411d when thinning-out light receiving control is performed on the light receiving element array 41 at a thinning rate of 1 / 2. In the example of Fig. 8(d), every other light receiving element is activated and every other light receiving element is deactivated in each row and column.

[0082] In the examples of FIGS. 8(c) and 8(d), similarly to the first embodiment, a distance measuring device is provided that can improve distance measurement performance while realizing eye safety.

[0083] Figures 8(e) and 8(f) are modified examples in which the arrangement of the thinning-out light receiving control is different. The thinning-out light emission control in Figure 8(e) is the same as that in Figure 8(c).

[0084] Fig. 8(f) shows a modified example of the arrangement of light receiving elements when thinning-out light receiving control is performed on the light receiving element array 41 at a thinning rate of 1 / 2. In the example of Fig. 8(f), four light receiving elements 411e, 411f, 411g, and 411h that are adjacent in the row and column directions are all enabled. As a result, the light receiving ranges of the light receiving elements 411e, 411f, 411g, and 411h are included in the light emitting range of the light emitting element 211a.

[0085] In the example of Fig. 8(f), the number of light receiving elements included in the light receiving range corresponding to the light emitting range is doubled compared to the example of Fig. 8(d). This can improve the effects of expanding the range of distances that can be measured or improving the frame rate. Furthermore, the light receiving count values ​​of the four light receiving elements in the light receiving element array 41 can be added together, which can improve the accuracy of peak determination or shorten the time required for peak determination.

[0086] 8(g) and 8(h) are modified examples showing a case where the area of ​​the light-emitting range of one light-emitting element 211 is not an integer multiple of the area of ​​the light-receiving range of the light-receiving element 411. In this modified example, control is performed by the projection optical system to adjust the projection position and projection range so that the light-emitting range of one light-emitting element 210 encompasses the light-receiving ranges of one or more light-receiving elements 411. Projection area R2 in FIG. 8(h) indicates the position and range onto which light emitted from light-emitting element 211c is projected. As shown in FIG. 8(h), projection area R2 encompasses the light-receiving range of light-receiving element 411i.

[0087] In this embodiment, as in the first embodiment, a distance measuring device that can improve distance measurement performance while realizing eye safety is provided.

[0088] [Fourth embodiment] In this embodiment, a case will be described in which the light emitting range of one light emitting element 211 is smaller than the light receiving range of one light receiving element 411. In this embodiment, the description of elements common to the first to third embodiments may be omitted or simplified.

[0089] 9(a) is a schematic diagram showing the thinning-out light emission control of the light emitting element array 21 according to this embodiment, and FIG. 9(b) is a schematic diagram showing the thinning-out light reception control of the light receiving element array 41.

[0090] Each box in FIG. 9(a) represents the light-emitting range of one light-emitting element, and each box in FIG. 9(b) represents the light-receiving range of one light-receiving element. As shown in FIGS. 9(a) and 9(b), the light-emitting range of one light-emitting element is narrower than the light-receiving range of one light-receiving element. In the examples of FIGS. 9(a) and 9(b), the area of ​​the light-receiving range of one light-receiving element is four times the area of ​​the light-emitting range of one light-emitting element, but this is not limited to this. For example, the area of ​​the light-receiving range of one light-receiving element may be an integer multiple of the area of ​​the light-emitting range of one light-emitting element. In other words, the light-receiving range of one light-receiving element may correspond to the light-emitting ranges of n light-emitting elements (n is an integer greater than or equal to 2).

[0091] In Fig. 9(a), hatched light-emitting elements 211a, 211b, 211c, and 211d indicate light-emitting elements in an emitting state, and non-hatched light-emitting elements indicate light-emitting elements in a non-emitting state. In Fig. 9(b), hatched light-receiving element 412a indicates an enabled light-receiving element, and non-hatched light-receiving elements indicate disabled light-receiving elements.

[0092] 9(a) shows a modified example of the arrangement of light-emitting elements when thinning-out light emission control of the light-emitting element array 21 is performed at a thinning rate of 1 / 2. In the example of FIG. 9(a), all four light-emitting elements 212a, 212b, 212c, and 212d adjacent in the row and column directions emit light. As a result, the light-receiving range of the light-receiving element 412a is encompassed by the combined light-emitting range of the four light-emitting elements 212a, 212b, 212c, and 212d.

[0093] Furthermore, similar to the examples of Figures 8(g) and 8(h), the projection optical system may be controlled to adjust the projection position and projection range so that the light-emitting range of one light-emitting element encompasses the light-receiving range of one or more light-receiving elements.

[0094] In this embodiment, as in the first embodiment, a distance measuring device that can improve distance measurement performance while realizing eye safety is provided.

[0095] [Fifth embodiment] 10(a) and 10(b) are block diagrams of devices related to an on-vehicle distance measuring device in this embodiment. The device 80 has a distance measurement unit 803, which is an example of the distance measuring device in the above-mentioned embodiment, and a signal processing device (processing device) that processes a signal from the distance measurement unit 803. The device 80 has the distance measurement unit 803 that measures the distance to an object, and a collision determination unit 804 that determines whether or not there is a possibility of collision based on the measured distance. Here, the distance measurement unit 803 is an example of a distance information acquisition means that acquires distance information to the object. In other words, the distance information is information related to the distance to the object, etc. The collision determination unit 804 may use the distance information to determine the possibility of collision.

[0096] The device 80 is connected to a vehicle information acquisition device 810 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The device 80 is also connected to a control ECU 820, which is a control device that outputs a control signal to generate a braking force for the vehicle based on the determination result of the collision determination unit 804. The device 80 is also connected to an alarm device 830 that issues an alarm to the driver based on the determination result of the collision determination unit 804. For example, if the collision determination unit 804 determines that there is a high possibility of a collision, the control ECU 820 performs vehicle control to avoid the collision and mitigate damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 830 warns the user by sounding an alarm, displaying alarm information on the screen of a car navigation system, etc., or vibrating the seat belt or steering wheel. These devices of the device 80 function as a mobile object control unit that controls the operation of controlling the vehicle as described above.

[0097] In this embodiment, the device 80 measures the distance around the vehicle, for example, the front or rear. Fig. 10(b) shows the device when measuring the distance in front of the vehicle (distance measurement range 850). A vehicle information acquisition device 810, which serves as a distance measurement control means, sends an instruction to the device 80 or the distance measurement unit 803 to perform a distance measurement operation. This configuration can further improve the accuracy of distance measurement.

[0098] Although the above describes an example of control to prevent collision with other vehicles, the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from a lane, etc. Furthermore, the present invention is not limited to vehicles such as automobiles, but can be applied to moving objects (moving devices) such as ships, aircraft, artificial satellites, industrial robots, and consumer robots. In addition, the present invention can be applied to a wide range of devices that use object recognition or biometric recognition, such as intelligent transport systems (ITS) and surveillance systems, without being limited to moving objects.

[0099] [Modified embodiment] The present invention is not limited to the above-described embodiments and can be modified in various ways. For example, an example in which part of the configuration of one embodiment is added to another embodiment, or an example in which part of the configuration of one embodiment is replaced with part of the configuration of another embodiment, is also an embodiment of the present invention.

[0100] The disclosure of this specification includes the complement of the concepts described in this specification. In other words, if this specification states, for example, that "A is B" (A=B), then this specification is deemed to disclose or suggest that "A is not B" even if the statement that "A is not B" (A≠B) is omitted. This is because when "A is B," it is assumed that the case where "A is not B" is taken into consideration.

[0101] The disclosure of this specification includes the following configurations. (Configuration 1) a light-emitting element array in which a plurality of light-emitting elements, each of which has variable light-emitting power, are arranged two-dimensionally; a thinning-out control unit that performs thinning-out light emission control so that some of the light-emitting elements among the plurality of light-emitting elements emit light and some of the light-emitting elements do not emit light; a power control unit that controls the light emitting power of each of the plurality of light emitting elements based on a first thinning rate indicating a ratio of light emitting elements that do not emit light among the plurality of light emitting elements so that the light emitting power per unit area does not exceed a threshold; A distance measuring device comprising: (Configuration 2) The power control unit controls the light emission power so that the light emission power increases as the first thinning rate increases. 2. The distance measuring device according to configuration 1, (Configuration 3) Each of the plurality of light-emitting elements includes a laser light source. 3. The distance measuring device according to configuration 1 or 2. (Configuration 4) The power control unit controls the light emission power by controlling the power supplied to each of the plurality of light emitting elements. 4. The distance measuring device according to any one of configurations 1 to 3. (Configuration 5) The threshold value is set to satisfy at least one of Class 1 of the International Electrotechnical Commission's IEC 60825-1, Class 1 of the Japanese Industrial Standards' JIS C 6802, and Class 1 of the European Standards' EN 60825-1. 5. The distance measuring device according to any one of configurations 1 to 4. (Configuration 6) The optical fiber further includes a photodetector array in which a plurality of photodetectors are arranged two-dimensionally, each of which generates a signal in response to incident light. 6. The distance measuring device according to any one of configurations 1 to 5, (Configuration 7) The thinning control unit performs thinning light receiving control to enable some of the plurality of light receiving elements and disable other parts. 7. The distance measuring device according to configuration 6, (Configuration 8) The first thinning rate is equal to a second thinning rate indicating a ratio of disabled light receiving elements among the plurality of light receiving elements. 8. The distance measuring device according to configuration 7. (Configuration 9) The first thinning rate and a second thinning rate indicating a ratio of disabled light receiving elements among the plurality of light receiving elements are different from each other. 8. The distance measuring device according to configuration 7. (Configuration 10) Each of the plurality of light receiving elements generates a light receiving count value by counting pulses corresponding to the incident light. 10. The distance measuring device according to any one of configurations 6 to 9, (Configuration 11) The thinning control unit determines the first thinning rate based on distance information from the distance measuring device to the object, the distance information being generated based on the signal output from the light receiving element. 11. The distance measuring device according to any one of configurations 6 to 10. (Configuration 12) The power control unit controls the light emitting power of each of the plurality of light emitting elements further based on the distance information. 12. The distance measuring device according to configuration 11. (Configuration 13) The light-emitting range of one of the light-emitting elements corresponds to the light-receiving ranges of m (m is an integer of 2 or more) of the light-receiving elements. 13. The distance measuring device according to any one of configurations 6 to 12. (Configuration 14) the thinning control unit performs thinning light receiving control to enable some of the plurality of light receiving elements and disable other parts, The m light receiving elements corresponding to the light emitting elements controlled to emit light by the thinning-out light emission control are all enabled. 14. The distance measuring device according to configuration 13. (Configuration 15) the thinning control unit performs thinning light receiving control to enable some of the plurality of light receiving elements and disable other parts, A part of the m light receiving elements corresponding to the light emitting elements controlled to emit light by the thinning-out light emission control is enabled, and the other part is disabled. 14. The distance measuring device according to configuration 13. (Configuration 16) The size of the light-emitting area of ​​one of the light-emitting elements and the size of the light-receiving area of ​​one of the light-receiving elements are different from each other, The light-emitting range of one of the light-emitting elements includes the light-receiving range of one of the light-receiving elements. 13. The distance measuring device according to any one of configurations 6 to 12. (Configuration 17) The light receiving range of one of the light receiving elements corresponds to the light emitting ranges of n (n is an integer of 2 or more) of the light emitting elements. 13. The distance measuring device according to any one of configurations 6 to 12. (Configuration 18) the thinning control unit performs thinning light receiving control to enable some of the plurality of light receiving elements and disable other parts, The n light-emitting elements corresponding to one of the light-receiving elements that is enabled are all controlled to emit light by the thinning-out light-emission control. 18. The distance measuring device according to configuration 17. (Configuration 19) a light-emitting element array in which a plurality of light-emitting elements, each of which has variable light-emitting power, are arranged two-dimensionally; a thinning-out control unit that performs thinning-out light emission control so that some of the light-emitting elements among the plurality of light-emitting elements emit light and some of the light-emitting elements do not emit light; a power control unit that controls the light emission power of each of the plurality of light emitting elements; and The thinning control unit sets a first thinning rate indicating a ratio of light-emitting elements that do not emit light among the plurality of light-emitting elements, based on the light-emitting power of each of the plurality of light-emitting elements, so that the light-emitting power per unit area does not exceed a threshold. A distance measuring device characterized by: (Configuration 20) A mobile object, a distance measuring device according to any one of configurations 1 to 19; a mobile object control unit that controls the mobile object based on distance information generated by the distance measuring device; A moving object comprising:

[0102] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0103] It should be noted that the above-described embodiments are merely examples of specific embodiments for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited by these embodiments. In other words, the present invention can be carried out in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0104] 1 Ranging device 21 Light-emitting element array 31 Thinning control unit 32 Laser power control unit 41 Photodetector array 210 Light-emitting element 410 Photodetector

Claims

1. a light-emitting element array in which a plurality of light-emitting elements, each of which has a variable light-emitting power, are arranged two-dimensionally; a thinning-out control unit that performs thinning-out light emission control so that some of the light-emitting elements among the plurality of light-emitting elements emit light and some of the light-emitting elements do not emit light; a power control unit that controls the light emitting power of each of the plurality of light emitting elements based on a first thinning rate indicating a ratio of light emitting elements that do not emit light among the plurality of light emitting elements so that the light emitting power per unit area does not exceed a threshold; A distance measuring device comprising:

2. The power control unit controls the light emission power so that the light emission power increases as the first thinning rate increases.

2. The distance measuring device according to claim 1.

3. Each of the plurality of light-emitting elements includes a laser light source.

2. The distance measuring device according to claim 1.

4. The power control unit controls the light emission power by controlling the power supplied to each of the plurality of light emitting elements.

2. The distance measuring device according to claim 1.

5. The threshold value is set to satisfy at least one of Class 1 of IEC 60825-1 of the International Electrotechnical Commission, Class 1 of JIS C 6802 of the Japanese Industrial Standards, and Class 1 of EN 60825-1 of the European Standards.

2. The distance measuring device according to claim 1.

6. The image sensor further includes a light receiving element array in which a plurality of light receiving elements are arranged two-dimensionally, each of which generates a signal in response to incident light.

2. The distance measuring device according to claim 1.

7. The thinning control unit performs thinning light receiving control to enable some of the plurality of light receiving elements and disable other parts.

7. The distance measuring device according to claim 6.

8. The first thinning rate is equal to a second thinning rate indicating a ratio of disabled light receiving elements among the plurality of light receiving elements.

8. The distance measuring device according to claim 7.

9. The first thinning rate and a second thinning rate indicating a ratio of disabled light receiving elements among the plurality of light receiving elements are different from each other.

8. The distance measuring device according to claim 7.

10. Each of the plurality of light receiving elements generates a light receiving count value by counting pulses corresponding to the incident light.

7. The distance measuring device according to claim 6.

11. The thinning control unit determines the first thinning rate based on distance information from the distance measuring device to the object, the distance information being generated based on the signal output from the light receiving element.

7. The distance measuring device according to claim 6.

12. The power control unit controls the light emitting power of each of the plurality of light emitting elements further based on the distance information.

12. The distance measuring device according to claim 11.

13. The light-emitting range of one of the light-emitting elements corresponds to the light-receiving ranges of m (m is an integer of 2 or more) of the light-receiving elements.

7. The distance measuring device according to claim 6.

14. the thinning control unit performs thinning light receiving control to enable some of the plurality of light receiving elements and disable other parts, The m light receiving elements corresponding to the light emitting elements controlled to emit light by the thinning-out light emission control are all enabled.

14. The distance measuring device according to claim 13.

15. the thinning control unit performs thinning light receiving control to enable some of the plurality of light receiving elements and disable other parts, A part of the m light receiving elements corresponding to the light emitting elements controlled to emit light by the thinning-out light emission control is enabled, and the other part is disabled.

14. The distance measuring device according to claim 13.

16. The size of the light-emitting range of one of the light-emitting elements and the size of the light-receiving range of one of the light-receiving elements are different from each other, The light-emitting range of one of the light-emitting elements includes the light-receiving range of one of the light-receiving elements.

7. The distance measuring device according to claim 6.

17. The light receiving range of one of the light receiving elements corresponds to the light emitting ranges of n (n is an integer of 2 or more) of the light emitting elements.

7. The distance measuring device according to claim 6.

18. the thinning control unit performs thinning light receiving control to enable some of the plurality of light receiving elements and disable other parts, The n light-emitting elements corresponding to one of the light-receiving elements to be enabled are all controlled to emit light by the thinning-out light emission control.

18. A distance measuring device according to claim 17.

19. a light-emitting element array in which a plurality of light-emitting elements, each of which has a variable light-emitting power, are arranged two-dimensionally; a thinning-out control unit that performs thinning-out light emission control so that some of the light-emitting elements among the plurality of light-emitting elements emit light and some of the light-emitting elements do not emit light; a power control unit that controls the light emission power of each of the plurality of light emitting elements; and The thinning control unit sets a first thinning rate indicating a ratio of light-emitting elements that do not emit light among the plurality of light-emitting elements, based on the light-emitting power of each of the plurality of light-emitting elements, so that the light-emitting power per unit area does not exceed a threshold value. A distance measuring device characterized by:

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

Images