Light projection / reception device, ranging system, and program

Abstract

To provide a light projection / reception device which enables more accurate ranging by eliminating the influence of measurement error due to voltage applied to a light reception unit.SOLUTION: A light projection / reception device is provided, comprising one or more light projection units for projecting light, one or more light reception units for receiving light reflected by an object, a power supply monitoring unit for monitoring power supply voltage applied to the light reception units to derive an applied voltage, and a control unit for controlling the light projection units, light reception units, and power supply monitoring unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light projecting and receiving device, a distance measuring system, and a program. [Background technology]

[0002] One of the conventional methods for measuring the distance to an object is the ToF (Time of Flight) method. A ToF camera, a distance measuring device using the ToF method, irradiates the object with infrared distance measurement light that is intensity-modulated using a predetermined irradiation pattern, and then receives the distance measurement light reflected by the object using an infrared image sensor. The ToF camera then detects the time difference between irradiation and reception for each pixel using the irradiation pattern, and calculates the distance. The ToF camera collects the calculated distance values ​​for each pixel in a bitmap format and saves them as a "distance image."

[0003] Patent Document 1 discloses that in order to solve the problem of measurement accuracy "changing periodically according to the phase of the measurement light," the phase is controlled based on the amount of fluctuation in the measurement target distance that occurs due to periodic fluctuations in measurement accuracy. Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional techniques do not take into consideration measurement errors due to the voltage applied to the light receiving section, and there is a problem in that distance measurement cannot be performed with sufficient accuracy.

[0005] The present invention has been made in view of the above, and has an object to eliminate the influence of measurement errors due to the voltage applied to the light receiving section, thereby enabling more accurate distance measurement. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention comprises one or more light-projecting units that project light, one or more light-receiving units that receive light reflected from an object, a power supply monitoring unit that monitors the power supply voltage applied to the light-receiving units and determines the applied voltage, and a control unit that controls the light-projecting units, the light-receiving units, and the power supply monitoring units. [Effects of the Invention]

[0007] According to the present invention, it is possible to eliminate the influence of measurement errors caused by the voltage applied to the light receiving section, thereby enabling distance measurement with higher accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing the hardware configuration of a distance measuring device including a light projecting and receiving device according to a first embodiment. [Figure 2] FIG. 2 is a timing chart for explaining the principle of distance measurement. [Figure 3] FIG. 3 is a diagram showing the relationship between the applied voltage and the measured distance value while the light receiving section is receiving light when measuring the distance to a specific target. [Figure 4] FIG. 4 is a diagram showing an example of fluctuations in applied voltage during distance measurement. [Figure 5] FIG. 5 is a functional block diagram illustrating a functional configuration of the control unit according to the first embodiment. [Figure 6] FIG. 6 is a functional block diagram illustrating a functional configuration of a control unit according to the second embodiment. [Figure 7] FIG. 7 is a flowchart showing an example of a distance measurement procedure according to the second embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of a distance measurement procedure according to the third embodiment. [Figure 9] FIG. 9 is a flowchart showing an example of a distance measurement procedure according to the fourth embodiment. [Figure 10] FIG. 10 is a block diagram showing the system configuration of a distance measuring system according to the fifth embodiment. [Figure 11] FIG. 11 is a functional block diagram showing the functional configuration of the control unit of the distance measuring device and the control unit of the external device according to the fifth embodiment. [Figure 12] FIG. 12 is a perspective view of the appearance of a distance measuring device according to the sixth embodiment. [Figure 13] FIG. 13 is a diagram illustrating an example of a schematic configuration of a distance measuring device. [Figure 14] FIG. 14 is a diagram showing an example of the arrangement of the optical system. [Figure 15] FIG. 15 is a diagram showing an example in which the distance measuring device is applied to an electronic information terminal that authenticates a user. [Figure 16] FIG. 16 is a diagram showing an example in which the distance measuring device is applied to an autonomous traveling system. [Figure 17] FIG. 17 is a diagram showing an example in which the distance measuring device is applied to an article inspection system. [Figure 18] FIG. 18 is a diagram showing an example in which the distance measuring device is applied to an operating device. [Figure 19] FIG. 19 is a diagram showing an example in which the distance measuring device is applied to a driving assistance system. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a light projecting and receiving device, a distance measuring system, and a program will be described in detail with reference to the accompanying drawings.

[0010] (First embodiment) 1 is a block diagram showing the hardware configuration of a distance measuring device 100 equipped with a light projecting and receiving device according to a first embodiment. The distance measuring device 100, which also functions as an imaging device, measures the distance from the distance measuring device 100 to an object. The distance measuring device 100 is a ToF (Time of Flight) camera that calculates the distance to the object based on the time between emitting light and receiving reflected light.

[0011] 1, the distance measuring device 100 includes a light projecting unit 1, a light receiving unit 2, an analog-to-digital converter (ADC) 3, a control unit 4, and a power supply monitoring unit 6. Note that the distance measuring device 100 may include multiple light projecting units or multiple light receiving units.

[0012] The light projecting unit 1 may be configured to include a light source 1a such as a VCSEL (Vertical Cavity Surface Emitting Laser) and a projection optical system such as a lens, a DOE (Diffractive Optical Element), a collimator, or an MLA (Micro Lens Array). With this configuration, the light projecting unit 1 projects a plurality of point-like light beams. That is, the light projected by the light projecting unit 1, which is made up of a plurality of point-like light beams (spot light beams), is an example of patterned light, which is light patterned into point-like beams so as to have an intensity distribution within the projected range (space). The light projecting unit 1 may be configured to project diffused light instead of point-like light. In this case, the light projecting unit 1 diffuses the light so as to achieve a substantially uniform brightness within the projection range.

[0013] The light receiving unit 2 can be an image sensor 2a and a light receiving optical system such as a lens. The image sensor 2a is a so-called ToF sensor. The image sensor 2a receives light that is irradiated from the light source 1a onto an object and reflected by the object or the like. As will be described in detail later, the image sensor 2a receives the reflected light at a timing with a predetermined phase delay relative to the projected light wave, and acquires an electrical signal based on the amount of charge corresponding to the intensity of the received reflected light for each pixel as a phase signal at each phase.

[0014] The ADC 3 converts the phase signal acquired for each pixel from an analog signal into digital data and supplies it to the control unit 4 .

[0015] The power supply monitoring unit 6 monitors the analog power supply voltage applied to the image sensor 2a and supplies the acquired voltage value to the control unit 4. To this end, the power supply monitoring unit 6 has a voltage monitoring ADC and memory, and the voltage monitoring ADC converts the analog value of the analog power supply voltage into a digital value and stores the digitally converted voltage value (applied voltage) in the memory. The control unit 4 acquires the applied voltage stored in the memory and uses it for the control described below. The voltage monitoring ADC may be realized by an ADC terminal provided in an FPGA (Field-Programmable Gate Array) that constitutes the control unit 4. This makes it possible to acquire the applied voltage while reducing the number of components in the distance measuring device 100.

[0016] The control unit 4 has a sensor I / F (Interface) 41, a light source driving circuit 42, an input / output interface (input / output I / F) 43, a CPU (Central Processing Unit) 44, a ROM (Read Only Memory) 45, a RAM (Random Access Memory) 46, and an SSD (Solid State Drive) 47. The sensor I / F 41, the light source driving circuit 42, the input / output I / F 43, the CPU 44, the ROM 45, the RAM 46, and the SSD 47 are electrically connected to one another via a system bus 48.

[0017] The sensor I / F 41 is an interface that acquires a phase signal from the image sensor 2a.

[0018] The input / output I / F 43 is an interface for connecting to an external device such as a main controller device or a personal computer (PC). The input / output I / F 43 is also used as an interface for receiving an input of a voltage value (applied voltage) from the power supply monitoring unit 6. The control unit 4 can also be configured to receive an input of a voltage value from the power supply monitoring unit 6 by providing a circuit separate from the input / output I / F 43.

[0019] Based on a control signal supplied from the CPU 44, the light source drive circuit 42 supplies a drive signal with a predetermined voltage waveform and a predetermined light emission frequency to the light projector 1, thereby time-modulating (temporally controlling) the light emission by the light projector 1. The drive signal supplied to the light source 1a can be a voltage waveform with a rectangular wave, a sine wave, or a predetermined waveform. The light source drive circuit 42 modulates and controls the frequency of the drive signal by changing the frequency of the voltage waveform.

[0020] The ROM 45 is a non-volatile semiconductor memory (storage device) that can retain programs or data even when the power is turned off. The ROM 45 stores programs or data such as BIOS (Basic Input / Output System) and OS (Operating System) settings that are executed when the CPU 44 starts up. The RAM 46 is a volatile semiconductor memory (storage device) that temporarily retains programs or data.

[0021] The SSD 47 is a non-volatile memory that stores various data and programs for executing processes by the control unit 4. As an example, the SSD 47 stores a distance measurement imaging program. As will be described in detail later, the control unit 4 executes this distance measurement imaging program to control the light projection unit 1 and the light reception unit 2 to project and receive light, and to control the image sensor 2a to separate an electrical signal corresponding to the intensity of the received reflected light into multiple phase signals and acquire them for each pixel. Note that instead of the SSD 47, another storage device such as an HDD (Hard Disk Drive) may be used.

[0022] The CPU 44 reads programs or data from a storage device such as the ROM 45 or the SSD 47 onto the RAM 46 and executes the processing, thereby controlling the entire control unit 4. Note that some or all of the functions of the CPU 44 may be realized by an electronic circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA.

[0023] Here, the principle of distance measurement using a general ToF camera will be explained.

[0024] (Phase signal acquisition operation) The image sensor 2a has, for example, two charge accumulation units (a first charge accumulation unit and a second charge accumulation unit) for one light receiving element, and can quickly switch between the charge accumulation units that accumulate charges. This allows it to simultaneously detect two opposite phase signals for one square wave. For example, it can simultaneously detect a 0-degree phase signal and a 180-degree phase signal. It can also simultaneously detect a 90-degree phase signal and a 270-degree phase signal. This means that distance measurement is possible through two light projection and light reception processes.

[0025] FIG. 2 is a timing chart for explaining the distance measurement principle. FIG. 2(a) shows the timing of light projection, and FIG. 2(b) shows the timing of reflected light obtained by light projection. FIG. 2(c) shows the timing when a 0-degree phase charge is accumulated in the first charge accumulation unit of the two charge accumulation units of image sensor 2a, and FIG. 2(d) shows the timing when a 180-degree phase charge is accumulated in the second charge accumulation unit. FIG. 2(e) shows the timing when a 90-degree phase charge is accumulated in the first charge accumulation unit of the two charge accumulation units of image sensor 2a, and FIG. 2(f) shows the timing when a 270-degree phase charge is accumulated in the second charge accumulation unit. The length of the charge accumulation period in each charge accumulation unit is the same for all phases, but the timing at which charge accumulation begins differs for each phase.

[0026] 2(c) to 2(f), the period during which the charge due to reflected light is accumulated in the first charge accumulation unit or the second charge accumulation unit is indicated by diagonal lines during the period during which the charge for each phase is accumulated. Specifically, as shown in FIG. 2(c), the charge for the 0-degree phase is accumulated in the first charge accumulation unit between the pulse edge at the end of light projection and the pulse edge at the start of receiving reflected light. As shown in FIG. 2(d), the charge for the 180-degree phase is accumulated in the second charge accumulation unit between the completion of charge accumulation for the 0-degree phase and the pulse edge at the end of receiving reflected light.

[0027] Similarly, as shown in Fig. 2(e), the charge at a phase of 90 degrees is accumulated in the first charge accumulation unit between the pulse edge at which reflected light reception begins and the pulse edge at which charge accumulation of the pulse that controls charge accumulation ends.As shown in Fig. 2(f), the charge at a phase of 270 degrees is accumulated in the second charge accumulation unit between the pulse edge at which charge accumulation of the 90 degree phase ends and the pulse edge at which reflected light reception ends.

[0028] In practice, in order to increase the amount of accumulated charge, the light is not projected as a single square wave but as a repeating square wave pattern, and switching control to the first and second charge storage units is also repeatedly performed according to the timing of projecting this repeating pattern of light.

[0029] (Calculating distance values) The signals (N0, N90, N180, and N270) acquired at four phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees are phase signals based on the amount of charge accumulated after light is received and divided into four phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees relative to the pulse period of the projected light (illumination light). Therefore, the phase difference angle φ can be calculated using the following formula.

[0030] φ=Arctan{(N90-N270) / (N0-N180)}

[0031] Furthermore, the delay time Td can be calculated from this phase difference angle φ using the following formula: where fm is the modulation frequency.

[0032] Td=φ / 2πfm

[0033] Furthermore, the distance value D to the target object can be calculated from this delay time Td using the following formula:

[0034] D = Td × c ÷ 2 (c: speed of light)

[0035] In the example shown in Figure 2, phase signals of 0 and 180 degrees are acquired in the first measurement. However, a phase signal may be generated by subtracting the amount of charge in the second charge storage unit from the amount of charge in the first charge storage unit acquired in the first measurement. In such a measurement, one phase signal is acquired with one light emission and exposure. Therefore, four light emissions and exposures are required to acquire phase signals for four phases, which doubles the shooting time compared to shooting without external light. However, the subtraction process has the advantage of reducing the effects of external light.

[0036] The signal obtained by subtracting the charge amount of the second charge storage unit (tap B) from the charge amount of the first charge storage unit (tap A) acquired in the first measurement using the above method is called a DCS (Differential Correlation Sample) signal. This DCS signal is converted into a distance image. The conversion method is the same as the method described above, and the phase difference angle φ is calculated using the following formula.

[0037] φ=Arctan{(DCS90-DCS270) / (DCS0-DCS180)} φ=Arctan[{(A90-B90)-(A270-B270)} / {(A0-B0)-(A180-B180)}]

[0038] Here, for example, DCS90 is the DCS signal at 90 degrees, A90 is the charge amount of tap A at 90 degrees, and B90 is the charge amount of tap B at 90 degrees. From this phase difference angle φ, the delay time Td and the distance value D to the target object can be calculated in the same way as in the method described above.

[0039] In the following explanation, the phase signal obtained by one light emission and exposure to reflected light is assumed to be a phase signal (DCS signal) obtained by subtracting the charge amount of the second charge storage unit from the charge amount of the first charge storage unit.

[0040] Next, we will explain measurement errors caused by the analog power supply voltage. When the analog power supply voltage applied to a ToF sensor changes, the distance measurement value output from the ToF sensor changes. In other words, errors in the distance measurement value (deterioration in distance measurement accuracy) occur due to changes in the analog power supply voltage.

[0041] Figure 3 shows the relationship between the applied voltage Von and the distance measurement value when measuring a specific distance as a target while the light receiving unit 2 is receiving light. As shown, even though the same distance is being measured, if the applied voltage increases, the distance measurement value based on the light receiving information output from the ToF sensor changes, and the accuracy of the distance measurement decreases.

[0042] For example, when multiple ToF sensors are placed close to each other to measure the distance of the entire celestial sphere, the size of the board on which the ToF sensors are mounted must be reduced, making it difficult to mount a power supply IC (Integrated Circuit) on the same board.For this reason, if power is supplied to the ToF sensor from outside the board on which the ToF sensor is mounted via a harness or the like, a voltage drop occurs due to an IR (Intensity of electric current-Resistance) drop caused by the resistance value of the harness.

[0043] Figure 4 is a diagram showing an example of fluctuations in applied voltage during distance measurement. Here, Voff is the applied voltage when the ToF sensor is not receiving reflected light (before light reception begins and after light reception ends), and Von is the applied voltage when the ToF sensor is receiving light (from the start of light reception to the end of light reception). The period during which the ToF sensor receives light (light reception period) is, for example, 1 ms. During the light reception period, the ToF sensor consumes current, so current is supplied to the ToF sensor from the power supply circuit. At this time, an IR drop of ΔV, as calculated in the following formula, occurs due to the consumed current I and the resistance component R of the harness between the power supply circuit and the ToF sensor.

[0044] ΔV=Voff-Von=I×R

[0045] As such, the magnitude of the IR drop ΔV varies depending on the current consumption I and the resistance component R. During distance measurement, the analog power supply current flowing through the ToF sensor changes dynamically, for example, from 0.24 to 3.57 A (amperes), depending on the temperature of the ToF sensor and changes in other applied voltages. The resistance value of the harness also changes with changes in the ambient temperature. When the current and resistance change in this way, the value of the IR drop changes, and so does the voltage applied to the ToF sensor, resulting in a decrease in distance measurement accuracy as described above.

[0046] Therefore, the distance measuring device 100 equipped with the light emitting and receiving device of this embodiment is able to perform distance measurement with higher accuracy by monitoring and controlling the analog power supply voltage applied to the ToF sensor during light reception.

[0047] Next, the function of the control unit 4 will be described.

[0048] Fig. 5 is a functional block diagram showing the functional configuration of the control unit 4. As shown in Fig. 5, the control unit 4 realizes the functions of a voltage control unit 440, an information storage unit 450, a distance calculation unit 460, and an output unit 470 by the CPU 44 executing a distance measurement imaging program stored in the SSD 47.

[0049] The voltage control unit 440 acquires the applied voltage output from the power supply monitoring unit 6 via an interface such as the input / output I / F 43, and controls the analog power supply voltage applied to the image sensor 2a based on the acquired applied voltage. For example, the voltage control unit 440 controls the analog power supply voltage to decrease if the input applied voltage is increasing, and controls the analog power supply voltage to increase if the input applied voltage is decreasing. This type of control makes it possible to maintain the applied voltage approximately constant, thereby improving the accuracy of distance measurement.

[0050] The information storage unit 450 stores the phase images of each phase, which are the light reception information from the image sensor 2a output from the ADC 3, in a storage unit such as the RAM 46, or controls the reading of the phase images from the storage unit. Note that the phase images are images configured from phase signals acquired for each pixel.

[0051] The distance calculation unit 460 calculates distance information indicating the distance to the object based on the multiple phase images stored by the information storage unit 450. Note that although the case where an indirect ToF sensor is used as the image sensor 2a has been described here, when a direct ToF sensor is used, the information storage unit 450 stores information based on the light reception timing at each pixel as light reception information, and the distance calculation unit 460 calculates the distance information based on this information.

[0052] Output unit 470 outputs distance information indicating the distance to the object calculated by distance calculation unit 460 as image information (distance image) to an external device via input / output I / F 43.

[0053] 5 are realized by software using a distance measurement imaging program, but all or part of these functions may be realized by hardware such as an integrated circuit (IC).

[0054] Thus, according to this embodiment, by monitoring the analog power supply voltage applied to the ToF sensor during light reception and controlling the analog power supply voltage according to changes in the value of the applied voltage, it is possible to perform more accurate distance measurements.

[0055] (Second embodiment) Next, a second embodiment will be described. As described above, the magnitude of the IR drop ΔV varies depending on the current consumption I and the resistance component R. Therefore, even if attempts are made to suppress changes in the applied voltage, the analog power supply voltage may vary during the light reception period, making it impossible to measure distance with a stable applied voltage. In this embodiment, the distance information calculated by the distance calculation unit 460 is corrected while controlling the analog power supply voltage (or instead of controlling the analog power supply voltage), thereby improving the accuracy of distance measurement.

[0056] 6 is a functional block diagram showing the functional configuration of the control unit 4 according to the present embodiment. The difference from the first embodiment is that the distance calculation unit 460 has a distance correction unit 461, and the voltage applied when the ToF sensor receives light (light-receiving applied voltage) is input to the distance calculation unit 460. In the following description of the present embodiment, the description of the same parts as in the first embodiment will be omitted, and only the parts that differ from the first embodiment will be described.

[0057] The distance correction unit 461 corrects the distance information using distance information calculated based on the applied voltage and light reception information obtained from the power supply monitoring unit 6. For example, the relationship between the applied voltage and the distance measurement value as shown in FIG. 3 is measured in advance and stored in the SSD 47 or the like, and the distance information is corrected using this relationship. Here, the relationship between the applied voltage and the distance measurement value can be expressed using coefficients of first-order approximation (linear approximation) or curve approximation. In this case, these coefficients are stored in the SSD 47 or the like, and the distance correction unit 461 calculates the corrected distance information using the coefficients read from the SSD 47 or the like, as well as the applied voltage and distance information. Note that the relationship between the applied voltage and the distance measurement value measured in advance and stored may be the relationship measured when the analog power supply voltage is controlled, or may be the relationship measured when the analog power supply voltage is not controlled. Alternatively, the relationships measured in both cases may be stored and switched for use in correction depending on whether the analog power supply voltage is controlled or not.

[0058] Furthermore, when the distance measuring device 100 includes multiple light receiving units, the relationship between the applied voltage and the distance measurement value that is measured and stored in advance may be a relationship common to all the light receiving units, or a relationship measured for each light receiving unit may be stored. The relationship common to all the light receiving units may be found by averaging the relationships measured for each light receiving unit, or the like.

[0059] 7 is a flowchart showing an example of a distance measurement procedure according to this embodiment. First, when a user presses a button or the like to start distance measurement and distance measurement begins, the light projecting unit 1 projects light, and the reflected light is received by the light receiving unit 2 (steps S10 and S11). Next, the distance calculation unit 460 obtains the applied voltage from the power supply monitoring unit 6 (step S12) and obtains light reception information from the information storage unit 450 (step S13).

[0060] Next, distance calculation unit 460 calculates distance information based on the received light information (step S14), and distance correction unit 461 corrects the distance information based on the applied voltage (step S15). Output unit 470 outputs a distance image generated from the corrected distance information (step S16).

[0061] Thus, according to this embodiment, by monitoring the analog power supply voltage applied to the ToF sensor during light reception and correcting the distance image according to changes in the value of the applied voltage, it is possible to perform more accurate distance measurements.

[0062] (Third embodiment) Next, a third embodiment will be described. This embodiment differs from the second embodiment in that the distance calculation unit 460 corrects the distance information when the applied voltage is within a predetermined range, and does not correct the distance information otherwise. Other operations are the same as those of the second embodiment, so detailed descriptions will be omitted.

[0063] 8 is a flowchart showing an example of a distance measurement procedure according to this embodiment. The processes in steps S20 to S24, S26, and S27 are the same as those in the second embodiment. After distance calculation unit 460 calculates distance information in step S24, distance calculation unit 460 determines whether the applied voltage Von while image sensor 2a is receiving light is within a predetermined range (step S25). If Von is within the predetermined range, distance correction unit 461 corrects the distance information based on the applied voltage (step S25: Yes, step S26), and if Von is not within the predetermined range, distance information is not corrected (step S25: No).

[0064] Here, the predetermined range is a range of values ​​experimentally determined in advance by measurement, etc. For example, the predetermined range can be a range of applied voltages in which the relationship between the applied voltage and the distance measurement value can be appropriately approximated by linear approximation, etc. In this case, appropriate approximation cannot be performed unless the applied voltage is within the predetermined range. Therefore, by not performing correction, unnecessary correction calculations can be avoided and the amount of processing required for distance measurement can be reduced.

[0065] Thus, according to this embodiment, the distance image is corrected in accordance with changes in the value of the applied voltage when the applied voltage is within a specified range, and the distance image is not corrected when the applied voltage is not within the specified range, thereby allowing correction to be performed when appropriate, thereby reducing the amount of processing required for ranging.

[0066] (Fourth embodiment) Next, a fourth embodiment will be described. This embodiment differs from the second embodiment in that, before starting light emission and reception, the control unit 4 determines whether the applied voltage is within a predetermined range, and if it is within the predetermined range, performs distance measurement, but if it is not within the predetermined range, does not perform distance measurement. Other operations are the same as those in the second embodiment, so detailed description will be omitted.

[0067] 9 is a flowchart showing an example of a distance measurement procedure according to this embodiment. First, when a user presses a button or the like to start distance measurement, the control unit 4 acquires the applied voltage (initial applied voltage) Voff before the image sensor 2a starts receiving light (step S30), and determines whether Voff is within a predetermined range (step S31). If Voff is within the predetermined range, the control unit 4 performs distance measurement and outputs a distance image generated from the corrected distance information (step S31: Yes, steps S32 to S38). On the other hand, if Voff is not within the predetermined range, the control unit 4 ends the process without performing distance measurement (step S31: No).

[0068] Here, the predetermined range is a range of values ​​experimentally determined in advance by measurement or the like. For example, the predetermined range can be the range of applied voltage within which the image sensor 2a can be driven normally. In this case, if the applied voltage is not within the predetermined range, normal distance measurement is not possible, and therefore distance measurement is stopped. When distance measurement is stopped, an error message, a warning sound, or the like may be displayed to notify the user that normal distance measurement is not possible.

[0069] Thus, according to this embodiment, distance measurement is performed when the applied voltage before distance measurement starts is within a specified range, and distance measurement is not performed when the applied voltage is not within the specified range, so that distance measurement can be performed when normal distance measurement is possible.

[0070] (Fifth embodiment) In the first to fourth embodiments, the distance measuring device 100 performs distance calculation, correction, etc., but this is not limited to this. FIG. 10 is a block diagram showing the system configuration of a distance measuring system 300 according to this embodiment. As shown in FIG. 10, the distance measuring system 300 has a system configuration in which a distance measuring device (image capturing device) 400 is connected to an external device 500 such as a PC or a cloud. In the distance measuring system 300, the distance measuring device 400 functions as an image capturing device that performs ToF imaging, and the external device 500 functions as a distance image generating device that performs processing such as distance calculation and correction. For example, the external device 500 has a control unit 5 that receives light reception information and an applied voltage from the distance measuring device 400 and controls the acquisition of a distance image.

[0071] 11 is a functional block diagram showing the functional configuration of the control unit 4 of the distance measuring device 400 and the control unit 5 of the external device 500 according to this embodiment. The difference from the second embodiment is that the control unit 4 includes an output unit 471, and the control unit 5 includes an information storage unit 550, a distance calculation unit 560 (and a distance correction unit 561), and an output unit 570 instead of the control unit 4. In the following description of this embodiment, the description of the same parts as in the second embodiment will be omitted, and only the differences from the second embodiment will be described.

[0072] Output unit 471 outputs the light reception information acquired by control unit 4 and the applied voltage at the time of light reception (light reception applied voltage). The light reception information is stored in a memory unit by information storage unit 550, and the applied voltage is input to distance calculation unit 560. Alternatively, the applied voltage information may be stored in association with the light reception information. Each functional unit of control unit 5 generates and outputs a distance image from the corrected distance information by operating in the same manner as each functional unit described in the second embodiment.

[0073] Thus, according to this embodiment, by performing processes such as distance calculation and correction in the external device 500, the distance measuring device 400 can be made smaller and the processing load of the distance measuring device 400 can be reduced, making it easier for users to handle the distance measuring device 400.

[0074] (Sixth embodiment) Next, a sixth embodiment will be described.

[0075] The sixth embodiment differs from the first to fourth embodiments in that an omnidirectional imaging device is used as the distance measuring device 100. In the following description of the sixth embodiment, the description of the same parts as those of the first to fourth embodiments will be omitted, and only the parts that differ from the first to fourth embodiments will be described.

[0076] Fig. 12 is an external perspective view showing the configuration of a distance measuring device 100 according to a sixth embodiment, Fig. 13 is a diagram showing an example of the schematic configuration of the distance measuring device 100, and Fig. 14 is a diagram showing an example of the arrangement of an optical system. In this embodiment, the distance measuring device 100 has a function as a ToF distance measuring device (ToF camera) and a function as a luminance camera (RGB camera), and captures images of the entire celestial sphere using the ToF camera and the luminance camera.

[0077] 12 to 14, the distance measuring device 100 includes first light-projecting units 20A and 20B, second light-projecting units 30A and 30B, a ToF light-receiving unit 60 as a light-receiving unit, a luminance light-receiving unit 80, and a control unit 120. The first light-projecting units 20A and 20B and the ToF light-receiving unit 60, and the second light-projecting units 30A and 30B and the ToF light-receiving unit 60 each function as a ToF distance measuring device, that is, a ToF camera, and the luminance light-receiving unit 80 functions as a luminance camera.

[0078] The first light-projecting units 20A and 20B and the second light-projecting units 30A and 30B each emit distance-measuring light (such as infrared light) toward a measurement target area. The first light-projecting units 20A and 20B include light sources 210A and 210B that emit infrared light and ToF light-projecting systems 211A and 211B (light-projecting optical systems) that are configured with optical elements that widen the divergence angle, and emit the light from the light sources 210A and 210B at a wide angle. The second light-projecting units 30A and 30B include light sources 310A and 310B that emit infrared light and ToF light-projecting systems 311A ​​and 311B (light-projecting optical systems) that are configured with optical elements that widen the divergence angle, and emit the light from the light sources 310A and 310B at a wide angle. The optical elements of the ToF light projection systems 211A, 211B, 311A, and 311B include, for example, lenses, DOEs (diffractive optical elements), and diffusers. The light sources 210A, 210B, 310A, and 310B are, for example, two-dimensional array VCSELs. In the distance measuring device 100 of this embodiment, the two first light projection units 20A and 20B are arranged facing in opposite directions to each other, and the two second light projection units 30A and 30B are arranged facing in opposite directions to each other.

[0079] The two first light-projecting units 20A, 20B and the two second light-projecting units 30A, 30B are structured lighting that irradiates patterned light (a dot pattern in this embodiment), which is an example of structured light, into a space.

[0080] The distance measurement light emitted from the first light-projecting units 20A, 20B and the second light-projecting units 30A, 30B is reflected by an object present in the measurement target area. The ToF light-receiving unit 60 receives the light reflected from the object in the measurement target area. The ToF light-receiving unit 60 includes a ToF sensor 110 sensitive to the distance measurement light and a ToF light-receiving optical system 112 (first light-receiving optical system) consisting of optical elements that guide the incident light to the ToF sensor 110. The optical elements of the ToF light-receiving optical system 112 include, for example, a lens. The ToF sensor 110 is a light-receiving element in which light-receiving pixels are arranged two-dimensionally. Each pixel corresponds to a position within the measurement target area, so the ToF light-receiving unit 60 can individually receive light from each position within the measurement target area. The distance measuring device 100 of this embodiment has four ToF light-receiving units 60 arranged facing in different directions.

[0081] The luminance light receiving unit 80 acquires a two-dimensional image using the CMOS sensor 33. The luminance light receiving unit 80 includes the CMOS sensor 33 for capturing a luminance image (RGB image), and a luminance light receiving optical system 113 (second light receiving optical system) made up of optical elements that guide incident light to the CMOS sensor 33. The optical elements of the luminance light receiving optical system 113 include, for example, a lens.

[0082] The distance measuring device 100 of this embodiment maps the luminance image (RGB image) obtained by the luminance light receiving unit 80 to the coordinate points obtained from the distance image. This enables the distance measuring device 100 to convert distance and shape information of the surrounding space into digital data with color information.

[0083] The control unit 120 drives or controls the first light projecting units 20A and 20B, the ToF light receiving unit 60, the luminance light receiving unit 80, and the second light projecting units 30A and 30B. The control unit 120 is connected to each of the light sources 210A, 210B, 310A, and 310B, the ToF sensor 110, and the CMOS sensor 33 via a cable, an FPC (Flexible Printed Circuit), an FFC (Flexible Flat Cable), or the like.

[0084] Here, the first light-projecting units 20A and 20B are an example of a first light-projecting unit that projects patterned light (structured light). The second light-projecting units 30A and 30B are an example of a second light-projecting unit that projects patterned light (structured light). The first light-projecting unit 20A and the second light-projecting unit 30A, which are arranged on the +X side in FIG. 13, irradiate their respective patterned lights toward the +X side of the distance measuring device 100. The first light-projecting unit 20A and the second light-projecting unit 30A are arranged so that their point-like lights do not overlap. Similarly, the first light-projecting unit 20B and the second light-projecting unit 30B, which are arranged on the -X side in FIG. 13, are arranged so that the point-like lights of their respective patterned lights irradiated toward the -X side of the distance measuring device 100 do not overlap. For example, this arrangement can be achieved by tilting the first light-projecting units 20A and 20B in the -Z direction and the second light-projecting units 30A and 30B in the +Z direction. The combination of inclinations of the light projecting units may be other than those described above. Furthermore, the patterned lights from different light projecting units may include areas where the point lights of each unit overlap. The ToF light receiving unit 60 is an example of a light receiving section to which incident light including projected light is incident. The luminance light receiving unit 80 outputs information including at least luminance.

[0085] 12 to 14, the distance measuring device 100 has a longitudinal shape that is long in the Z-axis direction. In the first stage of the distance measuring device 100, which is closest to the +Z direction, four ToF light receiving optical systems 112, each with a field angle of 120 degrees or more, are arranged so as to face three directions in the XY plane and one direction, the +Z direction. In the second stage, which is on the -Z side of the first stage of the distance measuring device 100, two ToF light projecting systems 211A and 211B, each with a field angle of 180 degrees or more, and two luminance light receiving optical systems 113, each with a field angle of 180 degrees, are arranged. The two ToF light projecting systems 211A and 211B face in opposite directions (+X direction and -X direction), and the two luminance light receiving optical systems 113 also face in opposite directions (+Y direction and -Y direction). Two ToF light projecting systems 311A ​​and 311B, each with an angle of view of 180 degrees or more, are arranged in the third stage, which is on the -Z side of the second stage of distance measuring device 100. The two ToF light projecting systems 311A ​​and 311B face in opposite directions (+X and -X directions). A control unit 120 and a battery 130 are arranged in the lower stage on the -Z side of distance measuring device 100. This allows for a compact arrangement of optical systems that cover the entire celestial sphere, making it possible to miniaturize the distance measuring device.

[0086] The control unit 120 controls the timing at which the first light-projecting units (light-projecting units) 20A and 20B and the second light-projecting units (light-projecting units) 30A and 30B project light, and detects light reception by the ToF light-receiving unit (light-receiving unit) 60. First, the control unit 120 controls the timing at which the light sources 210A and 210B are driven, causing them to emit light toward the measurement target area. The control unit 120 then photoelectrically converts the light received by the ToF sensor 110 and outputs the converted light as a distance image. At the same time, the control unit 120 causes the CMOS sensor 33 to capture an image and output a brightness image.

[0087] When a direct ToF sensor is used as the ToF sensor 110, the control unit 120 outputs a distance image based on the timing of light reception at each pixel. On the other hand, when an indirect ToF sensor is used as the ToF sensor 110, the control unit 120 outputs a phase image based on the amount of light received at each pixel at four different phases. The control unit 120 can generate a distance image from the four phase images.

[0088] In this embodiment, such an omnidirectional imaging device includes the power supply monitoring unit 6 described in the first to fourth embodiments, and the control unit 4 includes a voltage control unit 440 and a distance correction unit 461, thereby generating a highly accurate distance image. The analog power supply voltage applied to each of the four ToF light receiving units 60 is generated by a power supply circuit (DC / DC converter) in each circuit unit. The analog power supply voltage during the light receiving period of each ToF light receiving unit 60 is monitored by the power supply monitoring unit 6 that monitors each ToF light receiving unit 60. When the voltage monitoring ADC of the power supply monitoring unit 6 is implemented by an ADC terminal of the FPGA, separate pins are assigned as the ADC terminals that monitor each ToF light receiving unit 60. The digitally converted voltage value (applied voltage) may be stored in a memory provided in each power supply monitoring unit 6, or may be stored in a shared memory. Furthermore, the sixth embodiment may be implemented by dividing the functions between the distance measuring device 400 and the external device 500, as in the fifth embodiment.

[0089] As described above, according to this embodiment, even when an omnidirectional imaging device is used as the distance measuring device 100, distance information can be corrected in accordance with the applied voltage, and a more accurate distance image can be acquired.

[0090] Application examples in which the distance measuring device 100 described above in the first to sixth embodiments is used in various detection systems will be described with reference to FIGS. 15 to 19. The detection systems in these application examples have the respective functional blocks described below in addition to the distance measuring device 100. In FIGS. 15 to 19, functional blocks such as a determination unit provided in the detection system are depicted outside the detection system 50X for convenience of drawing. The various detection systems shown in FIGS. 15 to 19 have a system control unit that receives information from the distance measuring device 100 and controls the various detection systems and devices equipped with the various detection systems based on the information from the distance measuring device 100.

[0091] Fig. 15 is a diagram showing an example in which the distance measuring device is applied to an electronic information terminal that authenticates a user. Fig. 15 shows an example of a shape measurement system as a detection system, and is an application example in which the distance measuring device 100 is used for user authentication of an electronic device.

[0092] The portable information terminal 60X, which is an electronic device, has a function for authenticating a user. The authentication function may be realized by dedicated hardware, or may be realized by a CPU that controls the portable information terminal 60X executing a program stored in a ROM or the like. A detection system 50X mounted on the portable information terminal 60X uses a distance measuring device 100.

[0093] When authenticating a user, light is projected from a light source device of a distance measuring device 100 mounted on the portable information terminal 60X toward a user 61X using the portable information terminal 60X.

[0094] Light reflected by the user 61X and its surroundings is received by the light receiving element of the distance measuring device 100, and image data is generated (image is captured) by the image processing unit 62X. The judgment unit 63X judges the degree of match between the image information of the user 61X captured by the distance measuring device 100 and pre-registered user information, and determines whether the user is a registered user.

[0095] Specifically, the shapes (contours and irregularities) of the face, ears, head, etc. of the user 61X can be measured and used as user information.

[0096] In the application example of FIG. 15, the detection system 50X can detect the user 61X with high accuracy, similar to the distance measuring device 100 according to the first to sixth embodiments, and improvement in recognition accuracy can be achieved.

[0097] FIG. 15 shows an example in which the distance measuring device 100 is installed in a mobile information terminal 60X, but user authentication using the distance measuring device 100 can also be used in office automation equipment such as stationary PCs and printers, building security systems, and the like.

[0098] In terms of functionality, the device is not limited to personal authentication functions and can also be used for scanning three-dimensional shapes such as faces. In this case, too, highly accurate scanning can be achieved by incorporating the distance measuring device 100.

[0099] Fig. 16 is a diagram showing an example in which the distance measuring device is applied to an autonomous traveling system. Fig. 16 shows an example in which the distance measuring device 100 is applied to an autonomous traveling system in a moving body equipped with a detection system.

[0100] 16, the distance measuring device 100 is used to sense an object outside the moving body 70X. The moving body 70X is an autonomous moving body that can move automatically while recognizing the external situation.

[0101] A distance measuring device 100 is mounted on a moving object 70X, and the distance measuring device 100 emits light in the direction of travel of the moving object 70X and in the surrounding area. In a room 71X which is the moving area of ​​the moving object 70X, a desk 72X is installed in the direction of travel of the moving object 70X.

[0102] Of the light projected from the light source device of the distance measuring device 100 mounted on the moving body 70X, the light reflected by the desk 72X and its surroundings is received by the light receiving element of the distance measuring device 100, and the photoelectrically converted electrical signal is sent to the signal processing unit 73X.

[0103] Based on the electrical signals sent from the light receiving elements, the signal processing unit 73X calculates information about the layout of the room 71X, such as the distance to the desk 72X, the position of the desk 72X, and the surrounding conditions other than the desk 72X.

[0104] Based on the calculated information, a determination unit 74X determines the movement route, movement speed, etc. of the moving object 70X, and based on the determination result of the determination unit 74X, a driving control unit 75X controls the traveling of the moving object 70X. Here, the driving control unit 75X is an example of a system control unit included in the detection system 50X. Furthermore, the traveling of the moving object 70X is controlled by controlling the operation of a motor or the like, which is a driving source.

[0105] In the application example of Figure 16, the detection system 50X can detect the layout of the room 71X with high accuracy, similar to the distance measuring device 100 in the first to sixth embodiments, and the accuracy of the autonomous driving of the moving body 70X can be improved.

[0106] FIG. 16 shows an example in which the distance measuring device 100 is mounted on an autonomously traveling vehicle 70X that travels indoors 71X, but it can also be applied to an autonomously traveling vehicle (a so-called self-driving vehicle) that travels outdoors.

[0107] The present invention can also be applied to a driving assistance system for a mobile object such as an automobile that is not an autonomous driving type but is driven by a driver. In this case, the detection system 50X can detect the surrounding conditions of the mobile object and assist the driver in driving according to the detected surrounding conditions.

[0108] Fig. 17 is a diagram showing an example in which a distance measuring device is applied to an article inspection system. As shown in Fig. 17, a detection system 50X may be applied to an article inspection system in a factory or the like. Specifically, based on information acquired by the distance measuring device 100, a judgment unit 52X of the article inspection system (detection system 50X) judges the state of each article 51X.

[0109] 18 is a diagram showing an example in which the distance measuring device is applied to a moving device. As shown in FIG. 18, a detection system 50X may be applied to the operation control of a moving device.

[0110] Articulated arm 54X, which is a movable device, has multiple arms connected by bendable joints and is provided with hand unit 55X at the tip. Articulated arm 54X is used, for example, on a factory assembly line, and grasps object 56X with hand unit 55X when inspecting, transporting, or assembling object 56X.

[0111] The detection system 50X detects the object 56X and its surrounding area using the distance measuring device 100, and the determination unit 58X of the detection system 50X determines various information about the object 56X, such as the distance to the object 56X, the shape of the object 56X, the position of the object 56X, and the relative positions of multiple objects 56X if multiple objects 56X are present, based on the information acquired by the distance measuring device 100. Then, the drive control unit 59X controls the operation of the articulated arm 54X based on the determination result by the determination unit 58X. Here, the drive control unit 59X is an example of a system control unit included in the detection system 50X.

[0112] 19 is a diagram showing an example in which the distance measuring device is applied to a driving assistance system. As shown in FIG. 19, a detection system 50X may be applied to a driving assistance system for a moving body such as an automobile.

[0113] A detection system 50X mounted inside an automobile 64X uses a distance measuring device 100 to detect a driver 65X driving the automobile 64X and the surrounding area, and a determination unit 67X of the detection system 50X determines information such as the face (expression) and posture of the driver 65X based on the information acquired by the distance measuring device 100. Then, based on the determination result of the determination unit 67X, a driving control unit 68X provides appropriate driving assistance according to the situation of the driver 65X. Here, the driving control unit 68X is an example of a system control unit included in the detection system 50X.

[0114] The shape measurement system, autonomous driving system, article inspection system, mobile equipment, and driving assistance system described above are all examples of applications of the detection system. The detection system of this embodiment detects information based on a highly accurate distance image acquired by the distance measuring device 100, thereby enabling highly accurate detection.

[0115] Although various embodiments of the present invention have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These novel embodiments and modifications thereof are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, components from different embodiments and modifications may be combined as appropriate.

[0116] For example, aspects of the present invention are as follows. <1> This light-emitting and receiving device comprises one or more light-emitting units that emit light, one or more light-receiving units that receive light reflected from an object, a power supply monitoring unit that monitors the power supply voltage applied to the light-receiving units and determines the applied voltage, and a control unit that controls the light-emitting units, the light-receiving units, and the power supply monitoring unit, wherein the control unit controls the light-emitting and light-receiving units to obtain light-receiving information and obtains the applied voltage from the power supply monitoring unit. <2> The light receiving unit includes a plurality of light receiving units, and the applied voltage is acquired for each of the plurality of light receiving units. <1> 1 is a light projecting and receiving device according to the first embodiment. <3> the control unit acquires a light-receiving applied voltage, which is the applied voltage when receiving light to acquire the light-receiving information; <1> 1 is a light projecting and receiving device according to the first embodiment. <4> the control unit calculates distance information from the light emitting and receiving device to the object based on the light receiving information, and corrects the distance information based on the light receiving applied voltage; <3> 1 is a light projecting and receiving device according to the first embodiment. <5> the control unit corrects the distance information when the light-receiving applied voltage is within a predetermined range, and does not correct the distance information when the light-receiving applied voltage is not within the predetermined range; <4> 1 is a light projecting and receiving device according to the first embodiment. <6> the control unit acquires an initial applied voltage, which is the applied voltage before acquiring the light reception information, and controls the power supply voltage based on the initial applied voltage to control a light reception applied voltage, which is the applied voltage when receiving light to acquire the light reception information; <1> 1 is a light projecting and receiving device according to the first embodiment. <7> the light reception information and the light reception applied voltage are stored in association with each other in a storage unit; <3> ~ <6> 1. The light projecting and receiving device according to claim 1, wherein: <8> the control unit outputs the light reception information and the light reception applied voltage to the outside of the light emitting and receiving device; <3> ~ <6> 1. The light projecting and receiving device according to claim 1, wherein: <9> the control unit acquires an initial applied voltage, which is the applied voltage before acquiring the light reception information, and performs the light projection and reception when the initial applied voltage is within a predetermined range, and does not perform the light projection and reception when the initial applied voltage is not within the predetermined range; <1> ~ <6> 1. The light projecting and receiving device according to claim 1, wherein: <10> This is a ranging system comprising one or more light-projecting units that project light, one or more light-receiving units that receive light reflected from an object, a power supply monitoring unit that monitors the voltage applied to the light-receiving units, a control unit that controls the light-projecting units, the light-receiving units, and the power supply monitoring unit, and a distance calculation unit that calculates distance information to the object, wherein the control unit controls the light-projecting and light-receiving units to acquire light-receiving information and acquires the applied voltage from the power supply monitoring unit, and the distance calculation unit calculates the distance information based on the light-receiving information. <11> This program causes a computer to function as a light reception information acquisition means that acquires multiple pieces of light reception information obtained by receiving light that is projected from one or more light-projecting units and reflected by an object using one or more light-receiving units, an applied voltage acquisition means that acquires the applied voltage obtained from a power supply monitoring unit that monitors the applied voltage to the light-receiving units, and a distance calculation means that calculates distance information to the object, wherein the distance calculation means calculates the distance information based on the light reception information. [Explanation of symbols]

[0117] 1 Light emitter 2 Light receiving section 4. Control Unit 60 Light receiving section 100 Rangefinder 300 Ranging System 400 Range finding device (imaging device) 500 External equipment 450 Information Storage Department 440 Voltage control section 460 Distance calculation part 470 Output Section [Prior art documents] [Patent documents]

[0118] [Patent Document 1] Japanese Patent Application Publication No. 2022-146879

Claims

1. one or more light projecting units that project light; one or more light receiving units that receive reflected light that is reflected by an object; a power supply monitoring unit that monitors a power supply voltage applied to the light receiving unit and determines an applied voltage; a control unit that controls the light projecting unit, the light receiving unit, and the power supply monitoring unit, The control unit controlling light emission and reception by the light emitting unit and the light receiving unit to acquire light reception information, and acquiring the applied voltage from the power supply monitoring unit; Light emitting / receiving device.

2. the light receiving unit is a plurality of units, acquiring the applied voltage to each of the plurality of light receiving units; The light projecting and receiving device according to claim 1.

3. The control unit a light-receiving applied voltage, which is the applied voltage when receiving light to obtain the light-receiving information; The light projecting and receiving device according to claim 1.

4. The control unit calculating distance information from the light projecting and receiving device to the object based on the light reception information; correcting the distance information based on the light-receiving applied voltage; The light projecting and receiving device according to claim 3.

5. The control unit correcting the distance information when the light-receiving applied voltage is within a predetermined range; If the light-receiving applied voltage is not within the predetermined range, the distance information is not corrected. The light projecting and receiving device according to claim 4.

6. The control unit acquiring an initial applied voltage, which is the applied voltage before acquiring the light reception information; controlling the power supply voltage based on the initial applied voltage to control a light-receiving applied voltage, which is the applied voltage when receiving light to obtain the light-receiving information; The light projecting and receiving device according to claim 1.

7. the light reception information and the light reception applied voltage are stored in association with each other in a storage unit; The light emitting and receiving device according to any one of claims 3 to 6.

8. The control unit outputting the light reception information and the light reception applied voltage to the outside of the light emitting and receiving device; The light emitting and receiving device according to any one of claims 3 to 6.

9. The control unit acquiring an initial applied voltage, which is the applied voltage before acquiring the light reception information; When the initial applied voltage is within a predetermined range, the light emission and reception are performed. When the initial applied voltage is not within the predetermined range, the light projection and reception are not performed. The light emitting and receiving device according to any one of claims 1 to 6.

10. one or more light projecting units that project light; one or more light receiving units that receive reflected light that is reflected by an object; a power supply monitoring unit that monitors the voltage applied to the light receiving unit; a control unit that controls the light projecting unit, the light receiving unit, and the power supply monitoring unit; a distance calculation unit that calculates distance information to the object; Equipped with the control unit controls the light projection unit and the light reception unit to acquire light reception information, and acquires the applied voltage from the power supply monitoring unit; The distance calculation unit calculating the distance information based on the received light information; Ranging system.

11. Computer, a light reception information acquiring means for acquiring a plurality of pieces of light reception information obtained by receiving, with one or more light receiving units, light that is projected from one or more light projecting units and reflected by an object; an applied voltage acquisition unit that acquires the applied voltage acquired from a power supply monitoring unit that monitors the applied voltage of the light receiving unit; distance calculation means for calculating distance information to the object; It functions as The distance calculation means calculating the distance information based on the received light information; program.

Images