Distance measuring device

Abstract

The present invention provides a distance measuring device that can simulate the reproduction of laser light reflected by a simulated distant object. [Solution] The distance measuring device of the embodiment includes a first control unit that outputs a first signal, a light-emitting unit that emits a first laser beam based on the first signal, a reflecting object, a light-receiving unit that detects a second laser beam reflected by the reflecting object, a second control unit that outputs a second signal, an AD conversion unit that performs AD conversion on a third signal and a second signal corresponding to the second laser beam, respectively, a measurement unit, and an adjustment unit. When the first signal and the second signal are output simultaneously and the first laser beam is emitted, the measurement unit calculates a first detection time of the second laser beam based on first data corresponding to the third signal, and calculates a first rising edge time of the second signal based on second data corresponding to the second signal. The adjustment unit adjusts the output timing of the second signal based on the first detection time and the first rising edge time.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to a distance measuring device. [Background technology]

[0002] A rangefinder known as LiDAR (Light Detection and Ranging) is a well-known distance measuring device. LiDAR emits laser light from its laser light source towards a rangefinder target. The emitted laser light is reflected by the rangefinder target and detected by the LiDAR's light sensor. Based on this, the LiDAR calculates the time of flight (ToF) of the laser light based on the difference between the time the laser light was emitted and the time the reflected laser light was detected. Based on the time of flight of the laser light and the speed of the laser light, the LiDAR can then measure the distance between the LiDAR and the rangefinder target. This method of distance measurement is also called the "dToF (direct Time of Flight) method".

[0003] When LiDAR is used in transportation equipment such as railway vehicles, there is a requirement to detect objects at a distance (such as falling objects). However, if the amplification factor of the laser light source decreases due to aging or operating environment conditions, the detection limit of the LiDAR may shorten. If the detection limit shortens, there is a possibility that an accident may occur if an object is not detected while the vehicle is in motion. Similarly, if there is any malfunction in the LiDAR, there is a possibility that an accident may occur if an object is not detected while the vehicle is in motion. For this reason, it is desirable to diagnose the deterioration and malfunction of the LiDAR while the railway vehicle is stopped immediately after starting up the railway vehicle, and to confirm that there are no problems before putting the LiDAR into normal operation.

[0004] However, when railway vehicles are parked in a depot or train station, it is conceivable that a field of view and distance sufficient to measure the detection limit may not be available. Furthermore, when railway vehicles are parked on a station platform, if there are passengers on the platform, the laser beam output must be reduced for safety reasons.

[0005] If it is possible to simulate the reflection of laser light from a simulated distant object within the LiDAR, it is thought that it would be possible to diagnose the degradation or malfunction of the LiDAR while the train is stationary. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2023 / 234033 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention provides a distance measuring device that can simulate the reproduction of laser light reflected by a simulated distant object. [Means for solving the problem]

[0008] The distance measuring device of this embodiment comprises a first control unit, a light-emitting unit, a reflective object, a light-receiving unit, a second control unit, an AD conversion unit, a measurement unit, and an adjustment unit. The first control unit outputs a first signal. The light-emitting unit emits a first laser beam based on the first signal. The reflective object is positioned inside the light-emitting unit at a predetermined distance. The light-receiving unit detects a second laser beam corresponding to the first laser beam reflected by the reflective object. The second control unit outputs a second signal. The AD conversion unit performs AD conversion on the third signal corresponding to the second laser beam output from the light-receiving unit and the second signal received from the second control unit. When the first and second signals are output simultaneously at a first output timing, and the first laser beam is emitted with a first emission amount and a first pulse width, the measurement unit calculates a first detection time of the second laser beam based on the first data corresponding to the AD-converted third signal, and calculates a first rising edge time of the second signal based on the second data corresponding to the AD-converted second signal. The adjustment unit adjusts the output timing of the second signal to the second output timing based on the first detection time and the first rising edge time. [Brief explanation of the drawing]

[0009] [Figure 1] A block diagram showing an example of the configuration of a distance measuring device according to an embodiment. [Figure 2] A block diagram showing an example of the functional configuration of a distance measuring device according to this embodiment. [Figure 3] A diagram showing an example of the waveforms of various signals and laser light during the first processing of the distance measuring device according to the embodiment. [Figure 4] This figure shows an example of the waveforms of various signals and laser light after adjusting the signal output timing. [Figure 5] This figure shows an example of the waveforms of various signals and laser light when the control signal is output with a delay compared to the case in Figure 3. [Figure 6] This figure shows an example of various signals and laser light waveforms when a laser beam with reduced light emission intensity is emitted, compared to the case in Figure 3. [Figure 7] A diagram showing an example of the waveforms of various signals and laser light during the execution of the second processing of the distance measuring device according to the embodiment. [Figure 8] A diagram showing an example of various signals and the waveform of a laser beam when a second process is executed by widening the pulse width of the laser beam in the distance measurement device according to the embodiment. [Figure 9] A diagram showing an example of various signals and the waveform of a laser beam when a third process is executed in the distance measurement device according to the embodiment. [Figure 10] A diagram showing an example of a predetermined error range used for determination of the third process in the distance measurement device according to the embodiment. [Figure 11] A diagram showing the relationship between the received light amount of the laser beam and the detection efficiency. [Figure 12] A flowchart showing an example of the diagnostic operation of the distance measurement device according to the embodiment. [Figure 13] A block diagram showing an example of the configuration of the distance measurement device according to the first modification of the embodiment. [Figure 14] A block diagram showing an example of the configuration of the distance measurement device according to the second modification of the embodiment.

Modes for Carrying Out the Invention

[0010] Hereinafter, each embodiment will be described with reference to the drawings. Each embodiment exemplifies an apparatus and method for embodying the technical idea of the invention. The drawings are schematic or conceptual. Dimensions, ratios, etc. in each drawing are not necessarily the same as those in reality. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals.

[0011] <1> Embodiment A distance measuring device according to an embodiment will be described below. In the following description, a LiDAR, which is installed in front of a transport vehicle (railway vehicle) and has the function of measuring the distance to an external object (distance measuring function) and the function of diagnosing deterioration and malfunctions (diagnostic function), will be used as an example of a distance measuring device. In this embodiment, deterioration and malfunctions are diagnosed while the transport vehicle is stationary (the position of the LiDAR does not change) by simulating the reproduction of laser light reflected by a simulated distant object inside the LiDAR (hereinafter also referred to as "reproduction of reflected light by a simulated distant object"). Note that the transport vehicle on which the LiDAR is installed does not have to be a railway vehicle, but may be, for example, an automobile or a bus.

[0012] <1-1> Composition <1-1-1> Configuration of the rangefinder The configuration of the distance measuring device according to this embodiment will be explained with reference to Figure 1. Figure 1 is a block diagram showing an example of the configuration of the distance measuring device. As shown in Figure 1, the distance measuring device 1 includes, for example, a housing 2, an output / receiving window 3, a distance measuring control unit 11, a laser driver 12, a laser diode 13, an optical sensor 14, and an ADC (Analog-to-Digital Converter) 15.

[0013] The housing 2 is a box that houses the distance measuring control unit 11, laser driver 12, laser diode 13, optical sensor 14, and ADC 15.

[0014] The emission / receiving window 3 is provided in a part of the wall of the housing 2. The emission / receiving window 3 is a window that transmits laser light emitted from the laser diode 13 and laser light incident from the outside. The emission / receiving window 3 includes, for example, a glass material. In this embodiment, the emission / receiving window 3 also has the function of reflecting the laser light emitted from the laser diode 13. That is, in this embodiment, the emission / receiving window 3 is a reflective object placed inside the distance measuring device 1 (housing 2) at a predetermined distance from the laser diode 13.

[0015] The distance measurement control unit 11 is, for example, a computer. The distance measurement control unit 11 controls the overall operation of the distance measuring device 1. The distance measurement control unit 11 includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), an oscillator, a signal generator, and storage (not shown).

[0016] The ROM of the distance measuring control unit 11 stores the control program and other information for the distance measuring device 1.

[0017] The CPU of the distance measurement control unit 11 controls the laser driver 12, laser diode 13, optical sensor 14, and ADC 15 according to the control program.

[0018] The RAM of the distance measurement control unit 11 is used as the work area for the CPU of the distance measurement control unit 11.

[0019] The oscillator of the distance measuring control unit 11 is used to generate intermittent pulse signals. The oscillator of the distance measuring control unit 11 generates pulse signals PS1 and PS2 (hereinafter referred to as "signal PS1" and "signal PS2"). Signal PS1 is a signal that controls the laser driver 12 (output timing and output frequency of the laser light). The distance measuring control unit 11 transmits signal PS1 to the laser driver 12. Signal PS2 is a signal that controls the ADC 15 (sampling timing for AD conversion). The distance measuring control unit 11 transmits signal PS2 to the ADC 15.

[0020] The signal generator of the distance measurement control unit 11 is used to generate an analog pulse signal. The signal generator of the distance measurement control unit 11 generates an analog pulse signal PS3 (hereinafter referred to as "signal PS3"). Signal PS3 is a signal used to reproduce reflected light from a simulated distant object. The signal generator of the distance measurement control unit 11 has a function to adjust the output timing of signal PS3. The distance measurement control unit 11 transmits signal PS3 to the ADC 15.

[0021] The storage of the distance measurement control unit 11 stores, for example, data calculated by the diagnostic function. The distance measurement control unit 11 does not necessarily have its own storage; in this case, for example, external storage can be used.

[0022] The laser driver 12 is a circuit that drives the laser diode 13. Based on the signal PS1 received from the distance measurement control unit 11, the laser driver 12 generates a control signal CS (hereinafter referred to as "signal CS"). Signal CS is a pulse signal (drive voltage) that controls the emission of laser light. Increasing the drive voltage increases the amount of laser light emitted, and decreasing the drive voltage decreases the amount of laser light emitted. The laser driver 12 supplies signal CS to the laser diode 13.

[0023] The laser diode 13 is a laser light source. The laser diode 13 emits laser light based on the signal CS supplied by the laser driver 12. The laser diode 13 emits laser light when the signal CS is ON. A mirror may be placed in the optical path of the laser light to determine the direction of laser light emission.

[0024] In this embodiment, laser beam LE1 is used to measure the distance to an external object OB, and laser beam LE2 is used to reproduce reflected light from a simulated distant object. Laser beam LE2 has a lower emission intensity than laser beam LE1, for example. Laser beam LE1 emitted from the emission / receiving window 3 is reflected by the external object OB. The laser light reflected by the external object OB is denoted as "laser beam LR1". Laser beam LR1 is the reflected light corresponding to laser beam LE1. Laser beam LR1 is incident on the distance measuring device 1 from the emission / receiving window 3. Laser beam LE2 emitted from the laser diode 13 is reflected by the emission / receiving window 3. The laser light reflected by the emission / receiving window 3 is denoted as "laser beam LR2". Laser beam LR2 is the reflected light corresponding to laser beam LE2.

[0025] The optical sensor 14 is a light-receiving element that detects light. The optical sensor 14 detects the laser light LR1 that enters the distance measuring device 1 from the emission / receiving window 3. The optical sensor 14 also detects the laser light LR2 that is reflected by the emission / receiving window 3. The optical sensor 14 is positioned so that it is incident on the laser light LR1 emitted from the laser diode 13 and reflected by an object OB outside the distance measuring device 1, and the laser light LR2 emitted from the laser diode 13 and reflected by the emission / receiving window 3.

[0026] The light sensor 14 includes multiple pixels. Each pixel includes, for example, at least one photomultiplier element as an element that converts laser light into an electrical signal. As the photomultiplier element, for example, a single-photon avalanche diode (SPAD), which is a type of avalanche photodiode, is used. The light sensor 14 converts the laser light LR1 into an electrical signal. The light sensor 14 generates an electrical signal ES1 (hereinafter referred to as "signal ES1") by adjusting (amplifying) the output level of the converted electrical signal and transmits signal ES1 to the ADC 15. The light sensor 14 also converts the laser light LR2 into an electrical signal. The light sensor 14 generates an electrical signal ES2 (hereinafter referred to as "signal ES2") by adjusting (amplifying) the output level of the converted electrical signal and transmits signal ES2 to the ADC 15.

[0027] The ADC15 is a circuit that converts analog signals to digital signals. The ADC15 receives a signal PS2 from the distance measurement control unit 11. Based on the signal PS2, the ADC15 performs AD conversion at predetermined time intervals. The ADC15 converts the signal ES1 received from the optical sensor 14 into a digital signal. This generates time-series data DT1 (hereinafter referred to as "data DT1") corresponding to the AD-converted signal ES1 (laser light LR1). The ADC15 converts the signal ES2 received from the optical sensor 14 into a digital signal. This generates time-series data DT2 (hereinafter referred to as "data DT2") corresponding to the AD-converted signal ES2 (laser light LR2). The ADC15 also converts the signal PS3 received from the distance measurement control unit 11 into a digital signal. This generates time-series data DT3 (hereinafter referred to as "data DT3") corresponding to the AD-converted signal PS3. The ADC15 transmits data DT1, DT2, and DT3 to the distance measurement control unit 11.

[0028] The distance measuring control unit 11 measures the time and distance at which the optical sensor 14 detects the laser beam LR1 based on the data DT1 received from the ADC 15. The distance measuring control unit 11 detects the peak portion of the signal ES1 based on the data DT1 and calculates the time of the detected peak portion as the detection time of the laser beam LR1. The distance measuring control unit 11 calculates the Time of Flight (Tof) based on the difference between the time the laser diode 13 emitted the laser beam LE1 and the detection time of the laser beam LR1 reflected by the object OB. The distance measuring control unit 11 measures the distance between the distance measuring device 1 and the object OB based on the ToF and the speed of the laser beam LE1. The distance measuring control unit 11 transmits the distance measurement result RES (distance measurement information) to other external devices.

[0029] The distance measuring control unit 11 may calculate the emission time of the laser beam LE1 based on the time from the rising edge of the signal PS1, which has been measured in advance, until the laser beam is emitted from the laser diode 13, or it may measure the emission time of the laser beam LE1 by having the optical sensor 14 detect the laser beam LE1 emitted from the laser diode 13.

[0030] By using the laser beam LR2 emitted from the laser diode 13 and reflected by the emission / receiving window 3, it is possible to detect deterioration or malfunction of the optical sensor 14, ADC 15, and distance measuring control unit 11, even in open environments where there are no reflective objects outside the distance measuring device 1, or in environments where laser light cannot be emitted for safety reasons, such as environments where people walk. Furthermore, by adjusting the amount of light emitted from the laser beam LE2, it is possible to reproduce weak light.

[0031] However, because the laser diode 13 and the light emission / receiving window 3 are located relatively close to each other, the light sensor 14 detects the laser beam LR2 at time 0. Therefore, it is difficult to confirm the normal function and performance of the ADC 15 and the distance measuring control unit 11.

[0032] Therefore, in this embodiment, the reflection of the laser beam LE2 within the distance measuring device 1 and the signal PS3 are used to reproduce the reflected light from a simulated distant object. This allows for the diagnosis of deterioration or malfunction of the distance measuring device 1. Details of the diagnostic function will be described later.

[0033] <1-1-2> Functional configuration of the rangefinder The functional configuration of the distance measuring device 1 will be explained using Figure 2. Figure 2 is a block diagram showing an example of the functional configuration of the distance measuring device 1. As shown in Figure 2, the distance measuring device 1 functions as a first timing control unit 101, an emission control unit 102, a light emission unit 103, a light receiving unit 104, a second timing control unit 105, an AD conversion unit 106, a third timing control unit 107, a measurement unit 108, an adjustment unit 109, a first determination unit 110, and a second determination unit 111. In other words, the distance measuring device 1 includes a first timing control unit 101, an emission control unit 102, a light emission unit 103, a light receiving unit 104, a second timing control unit 105, an AD conversion unit 106, a third timing control unit 107, a measurement unit 108, an adjustment unit 109, a first determination unit 110, and a second determination unit 111.

[0034] The first timing control unit 101 is a functional block corresponding to the distance measurement control unit 11. The emission control unit 102 is a functional block corresponding to the laser driver 12. The light emission unit 103 is a functional block corresponding to the laser diode 13. The light receiving unit 104 is a functional block corresponding to the light sensor 14. The second timing control unit 105 is a functional block corresponding to the distance measurement control unit 11. The AD conversion unit 106 is a functional block corresponding to the ADC 15. The third timing control unit 107, the measurement unit 108, the adjustment unit 109, the first determination unit 110, and the second determination unit 111 are functional blocks corresponding to the distance measurement control unit 11.

[0035] (Distance measurement function) The distance measurement function will be explained using Figure 2. Specifically, the distance measuring device 1 performs the following processes.

[0036] The second timing control unit 105 generates the signal PS2 and outputs the signal PS2 to the AD conversion unit 106.

[0037] The first timing control unit 101 generates signal PS1 and outputs signal PS1 to the output control unit 102.

[0038] The emission control unit 102 generates a signal CS based on the signal PS1 received from the first timing control unit 101 and outputs the signal CS to the light emission unit 103.

[0039] The light-emitting unit 103 emits laser light LE1 based on the signal CS output from the emission control unit 102.

[0040] The light receiving unit 104 detects the laser beam LR1 corresponding to the laser beam LE1 that has been reflected by an external object OB and entered the distance measuring device 1 from the emission / receiving window 3. The light receiving unit 104 generates a signal ES1 by converting the laser beam LR1 into an electrical signal and outputs the signal ES1 to the AD conversion unit 106.

[0041] The AD conversion unit 106 performs AD conversion on the signal ES1 based on the signal PS2 received from the second timing control unit 105. The AD conversion unit 106 outputs data DT1 corresponding to the AD converted signal ES1 to the measurement unit 108.

[0042] As described above, the measurement unit 108 measures the time when the light receiving unit 104 detected the laser light LR1, and the distance between the distance measuring device 1 and the object OB, based on the data DT1 received from the AD conversion unit 106.

[0043] (Diagnostic function) As described above, in this embodiment, the reflection of the laser beam LE2 within the distance measuring device 1 and the signal PS3 are used to reproduce the reflected light from a simulated distant object. This allows for the diagnosis of deterioration or malfunction of the distance measuring device 1. Specifically, the distance measuring device 1 performs the following first, second, and third processes.

[0044] (First process) The first process involves adjusting the output timing (output time) of signal PS3, and determining the time origin T0 and distance origin D0. The time origin T0 is the reference time used to calculate the Time of Flight (ToF) with a pseudo-distant object. The distance origin D0 is the reference position used to calculate the distance with a pseudo-distant object.

[0045] The first process will be explained below using Figures 2 and 3. Figure 3 is a diagram showing an example of the waveforms of various signals and laser light during the execution of the first process. In Figure 3, the waveforms of signal PS2, signal CS, laser light LE2, signal PS3 output from the third timing control unit 107, signal ES2 received by the AD conversion unit 106, and signal PS3 received by the AD conversion unit 106 are shown. The horizontal axis represents time.

[0046] As shown in Figures 2 and 3, the second timing control unit 105 generates a signal PS2 and outputs the signal PS2 to the AD conversion unit 106 at time T1. Note that time T1 can be set to any arbitrary time.

[0047] The first timing control unit 101 generates signal PS1 and outputs signal PS1 to the output control unit 102.

[0048] The emission control unit 102 generates a signal CS based on the signal PS1 received from the first timing control unit 101, and outputs the signal CS to the light emission unit 103 at time T2. Hereinafter, time T2 will also be referred to as the "first output timing".

[0049] The third timing control unit 107 generates the signal PS3 and outputs the signal PS3 to the AD conversion unit 106 at the first output timing (simultaneously with the output timing of the signal CS by the output control unit 102).

[0050] At time T3, the light-emitting unit 103 emits laser light LE2 with a light emission intensity Lie1 and pulse width PW1 based on the signal CS output from the emission control unit 102.

[0051] The light receiving unit 104 detects the laser light LR2 corresponding to the laser light LE2 reflected by the emission / receiving window 3. The light receiving unit 104 generates a signal ES2 by converting the laser light LR2 into an electrical signal and outputs the signal ES2 to the AD conversion unit 106.

[0052] The AD conversion unit 106 performs AD conversion on the signal ES2 corresponding to the laser light LR2 output from the light receiving unit 104 based on the signal PS2 received from the second timing control unit 105. The AD conversion unit 106 outputs data DT2 corresponding to the AD converted signal ES2 to the measurement unit 108.

[0053] Furthermore, the AD conversion unit 106 performs AD conversion on the signal PS3 received from the third timing control unit 107 based on the signal PS2 received from the second timing control unit 105. The AD conversion unit 106 outputs data DT3 corresponding to the AD converted signal PS3 to the measurement unit 108.

[0054] The measurement unit 108 measures the time and distance at which the light receiving unit 104 detects the laser beam LR2 based on the data DT2. Specifically, the measurement unit 108 detects the peak portion of the signal ES2 based on the data DT2. In the example in Figure 3, the peak portion is detected at time Tp2. The measurement unit 108 calculates (quantifies) the time Tp2 of the detected peak portion as the detection time Td (reception time) of the laser beam LR2. The measurement unit 108 calculates ToF based on the difference between the time T3 at which the light emitting unit 103 emitted the laser beam LE2 and the detection time Td of the laser beam LR2 reflected by the emission / receiving window 3. The measurement unit 108 calculates the distance D1 based on ToF and the speed of the laser beam LE2. The measurement unit 108 transmits time Td to the adjustment unit 109.

[0055] Furthermore, the measurement unit 108 measures the detection time and distance based on the data DT3, assuming that the light receiving unit 104 has detected the laser light LR2. Specifically, the measurement unit 108 detects the peak portion of the signal PS3 based on the data DT3. In the example in Figure 3, the peak portion is detected at time Tp1. The measurement unit 108 calculates (quantifies) the time Tp1 of the detected peak portion as the rising edge time Tr (detection time) of the signal PS3. The measurement unit 108 calculates ToF based on the difference between the time T2 when the third timing control unit 107 outputs the signal PS3 and the rising edge time Tr of the signal PS3. The measurement unit 108 calculates the distance D2 based on ToF and the speed of the laser light LE2. The measurement unit 108 transmits the time Tr to the adjustment unit 109.

[0056] The adjustment unit 109 adjusts the timing at which the third timing control unit 107 outputs the signal PS3 based on the time Td and time Tr received from the measurement unit 108. Specifically, the adjustment unit 109 adjusts the timing at which the third timing control unit 107 outputs the signal PS3 so that time Td (=Tp2) and time Tr (=Tp1) coincide (matching the numerically represented times Td and Tr). As a result, the timing at which the third timing control unit 107 outputs the signal PS3 is adjusted to time T4 (=T2+ΔT1). Time ΔT1 = Td-Tr. Hereinafter, time T4 will also be referred to as the "second output timing". The timing at which the third timing control unit 107 outputs the signal PS3 may be adjusted so that the difference between time Td and time Tr is minimized. Furthermore, the subtraction of Td-Tr may be performed by the AD conversion unit 106. The adjustment unit 109 stores the second output timing Tout (=T4) in the storage mentioned above.

[0057] Furthermore, the adjustment unit 109 sets the time Td (=Tp2) received from the measurement unit 108 as the time origin T0, and sets the light emission / receiving window 3 as the distance origin D0.

[0058] Figure 4 shows the waveforms of various signals and laser light when signals PS2, CS, and PS3 are output in the same manner as in Figure 3 after adjusting the output timing of signal PS3. In Figure 4, the dashed line shows the waveform of signal PS3 before adjustment as shown in Figure 3. The waveforms of signal PS2, signal CS, laser light LE2, and signal ES2 are the same as those shown in Figure 3.

[0059] As shown in Figure 4, suppose the third timing control unit 107 outputs the signal PS3 to the AD conversion unit 106 at a time T4 that is ΔT1 later than the first output timing (time T2) before adjustment. In this case, the rising edge time Tr of the signal PS3 received by the AD conversion unit 106 will be ΔT1 later than before adjustment. Therefore, the measurement unit 108 calculates the rising edge time Tr of the signal PS3 as a time Tp2 that is ΔT1 later than the rising edge time Tr (=Tp1) of the signal PS3 before adjustment.

[0060] (Second process) The second process involves adjusting the laser light emission timing (signal CS output timing) and the amount of laser light emitted to reproduce reflected light from a simulated distant object.

[0061] First, let's discuss adjusting the timing of laser beam emission.

[0062] Figure 5 shows the waveforms of various signals and laser light when the signal CS is output with a delay compared to the case in Figure 3. In Figure 5, the dashed lines show the waveforms of signal CS, laser light LE2, and signal ES2 as shown in Figure 4. The waveforms of signals PS2 and PS3 are the same as those shown in Figure 4.

[0063] As shown in Figure 5, suppose the emission control unit 102 generates a signal CS based on the signal PS1 received from the first timing control unit 101 and outputs the signal CS to the light projection unit 103 at a time that is arbitrarily later than the first output timing (time T2). In this case, the emission time of the laser light LE2 emitted by the light projection unit 103 becomes later. As a result, the detection time Td of the laser light LR2 becomes later with respect to the time origin T0 (=Tp2).

[0064] Next, we will explain how to adjust the intensity of the laser light emitted.

[0065] Figure 6 shows the waveforms of various signals and laser light when a laser beam LE2 with reduced light emission intensity is emitted compared to the case in Figure 3. In Figure 6, the dashed lines show the waveforms of the laser beam LE2 and signal ES2 as shown in Figure 4. The waveforms of signal PS2, signal CS, and signal PS3 are the same as those shown in Figure 4.

[0066] As shown in Figure 6, suppose the light-emitting unit 103 emits laser light LE2 with an emission light intensity and pulse width PW1 that is arbitrarily lower than the emission light intensity Lie1, based on the signal CS output from the emission control unit 102. In this case, the value of the signal ES2 received by the AD conversion unit 106 (the received light intensity Lir of the laser light LR2) will be smaller than in the case of emission light intensity Lie1.

[0067] The time at which the laser beam LR1 reflected by an external object OB is detected by the light receiving unit 104 increases as the distance between the distance measuring device 1 and the object OB increases. Also, the laser beam LR1 emitted from the light emitting unit 103 and reflected by the object OB is attenuated more than the emitted laser beam LE1 due to reflection and scattering. The attenuation of the reflected laser beam LR1 increases as the distance to the object OB increases. Therefore, by delaying the emission timing of the laser beam LE2 (output timing of signal CS) and reducing the emitted light intensity Lie1 of the laser beam LE2, it is possible to reproduce reflected light (laser beam LR2) from a pseudo-distant object.

[0068] The second process will be explained below using Figures 2 and 7.

[0069] Figure 7 shows an example of the waveforms of various signals and laser light during the execution of the second process. In Figure 7, the dashed lines represent the waveforms of signal CS, laser light LE2, and signal ES2, as shown in Figure 4. The waveforms of signals PS2 and PS3 are the same as those shown in Figure 4.

[0070] As shown in Figures 2 and 7, the second timing control unit 105 generates a signal PS2 and outputs the signal PS2 to the AD conversion unit 106 at time T1. Time T1 can be set to any arbitrary time.

[0071] The first timing control unit 101 generates signal PS1 and outputs signal PS1 to the output control unit 102.

[0072] The emission control unit 102 generates a signal CS based on the signal PS1 received from the first timing control unit 101, and outputs the signal CS to the light projection unit 103 at a time T5 that is time ΔT2 later than the first output timing (time T2). The initial value ΔT20 of time ΔT2 is, for example, a predetermined time. Hereafter, time T5 will also be referred to as the "third output timing".

[0073] At time T6, based on the signal CS output from the emission control unit 102, the light-emitting unit 103 emits laser light LE2 with an emission light intensity LIe2 that is ΔLI1 lower than the emission light intensity LIe1 and a pulse width PW1.

[0074] The light receiving unit 104 detects the laser light LR2 corresponding to the laser light LE2 reflected by the emission / receiving window 3. The light receiving unit 104 generates a signal ES2 by converting the laser light LR2 into an electrical signal and outputs the signal ES2 to the AD conversion unit 106.

[0075] The AD conversion unit 106 performs AD conversion on the signal ES2 received from the light receiving unit 104 based on the signal PS2 received from the second timing control unit 105. The AD conversion unit 106 outputs data DT2 corresponding to the AD converted signal ES2 to the measurement unit 108.

[0076] The measurement unit 108 detects the peak portion of the signal ES2 based on the data DT2. In the example in Figure 7, the peak portion is detected at time Tp3. The measurement unit 108 calculates the time Tp3 of the detected peak portion as the detection time Td of the laser light LR2. The measurement unit 108 calculates ToF based on the difference between the time origin T0 (=Tp2) and the detection time Td (=Tp3) of the laser light LR2 reflected by the emission / receiving window 3. The measurement unit 108 calculates the distance D3 between the distance origin D0 (emission / receiving window 3) and the pseudo-distant object based on ToF and the velocity of the laser light LE2. That is, the measurement unit 108 calculates the distance D3 based on the time origin T0 and time Td. The measurement unit 108 transmits the distance D3 to the first determination unit 110.

[0077] The process described below is repeated in the same manner as in Figure 7, with time ΔT2 being increased by a constant amount of time ΔT2a (hereinafter, this repeated process will be referred to as the "first iteration"). Specifically, in the first iteration, time ΔT2 is set to (initial value ΔT20 + k × time ΔT2a) (where k is a non-negative integer), and the process described in Figure 7 is repeated i times (where i is a non-negative integer). That is, the measurement unit 108 calculates the distance D3 i times. The distance D3 calculated on the (k+1)th iteration is called "distance D3 k+1 It is also written as . In the first iteration, time ΔT2 is set to ΔT20, in the second iteration, time ΔT2 is set to ΔT20 + ΔT2a, in the third iteration, time ΔT2 is set to ΔT20 + 2 × ΔT2a, and so on.

[0078] As time ΔT2 increases, the amount of light LIr (value of signal ES2) of the laser light LR2 detected by the light receiving unit 104 decreases. Therefore, depending on the amount of light LIr, the measurement unit 108 may calculate a peak portion in data DT2 where the rising edge indicating the detection time of the laser light LR2 is buried in noise, and a portion other than the rising edge is used as the peak portion. Also, if the speed of the laser light LE2 is constant, it is thought that as time ΔT2 increases by a constant amount of time ΔT2a, the distance D3 calculated by the measurement unit 108 increases by a constant amount of distance ΔD3.

[0079] Therefore, the first determination unit 110 determines, for example, the distance D3 calculated on the (k+2)th time. k+2 However, the distance D3 calculated on the (k+1)th time k+1 It is determined whether the sum of the time ΔT2a and the distance ΔD3 (the distance calculated based on the time ΔT2a and the speed of the laser light LE2) falls within a predetermined error range ERG1 (for example, an error rate ERT1 of about 5%). The error rate ERT1 is, for example, (|D3 k+1 +ΔD3-D3 k+2 | / (D3 k+1 It is calculated by (+ΔD3)) × 100. Note that the error rate ERT1 may be calculated by other methods.

[0080] Distance D3 calculated on the (k+2)th iteration k+2When it falls within the error range ERG1, the first determination unit 110 determines that the rising part indicating the detection time of the laser beam LR2 has been detected in the (k + 2)-th process. In this case, the (k + 3)-th process is executed.

[0081] On the other hand, the distance D3 calculated in the (k + 2)-th k+2 When it does not fall within the error range ERG1, the first determination unit 110 determines that the rising part indicating the detection time of the laser beam LR2 has not been detected in the (k + 2)-th process. In this case, the first determination unit 110 calculates the distance D3 calculated in the (k + 1)-th k+1 as the reproduced distance D3a, and stores the reproduced distance D3a in the above storage. The reproduced distance D3a represents the distance that the distance measuring device 1 can measure. Also, the first determination unit 110 determines the time ΔT2 = initial value ΔT20+(k + 1)×time ΔT2a set in the (k + 1)-th as the delay time ΔT2’. Thereby, the first repetition process ends. The first repetition process is executed, for example, once a day.

[0082] Here, assume that the first repetition process is executed once a day, and has been executed a total of j days (j times) so far (j is an integer of 2 or more), that is, the calculation of the reproduced distance D3a by the first determination unit 110 has been performed j times, and j reproduced distances D3a are stored in the above storage. The reproduced distance D3a stored in the j-th time is denoted as "reproduced distance D3a j ".

[0083] As the received light amount LIr of the laser beam LR2 decreases, the possibility that the rising part indicating the detection time of the laser beam LR2 is buried in noise increases. Therefore, as the received light amount LIr decreases, the reproduced distance D3a jIt is thought that the amount of light received Lir will decrease. A decrease in the amount of light received Lir means deterioration or failure of the distance measuring device 1, such as a decrease in the amplification factor of the laser light in the light emitting unit 103, or a decrease in the photoelectric conversion efficiency or amplification factor in the light receiving unit 104. Therefore, the first determination unit 110 determines whether the distance measuring device 1 has deteriorated or failed based on the j stored reproduced distances D3a. Specifically, the first determination unit 110 determines, for example, the reproduced distance D3a calculated on the jth time j and the reproduction distance D3a calculated in the (j-1)th time. j-1 Compare this with the reproduction distance D3a. j The reproduction distance is D3a j-1 If the value is shorter than the specified value, the first determination unit 110 determines that the distance measuring device 1 is deteriorated or malfunctioning. This makes it possible to detect deterioration or malfunction of the distance measuring device 1, such as deterioration or malfunction of the light-emitting unit 103 (laser light output side) and deterioration or malfunction of the light-receiving unit 104 (laser light receiving side), as described above.

[0084] In the second process, only the time at which the signal CS is output from the ejection control unit 102 is delayed, so the rising edge of the signal ES2 is in an ideal state. Therefore, the detection time Td and the reproducible distance D3a j This reduces the variation in the measurement, resulting in high stability in distance measurement from day to day.

[0085] Furthermore, the laser beam emission timing (output timing of signal CS) may be delayed, the laser beam emission intensity may be reduced, and the laser beam pulse width may be widened. This is to account for the fact that the laser beam pulse may become less sharp due to light from a greater distance.

[0086] Figure 8 shows an example of the waveforms of various signals and laser light when the pulse width of the laser light is widened and the second processing is performed. In Figure 8, the dashed lines show the waveforms of signal CS, laser light LE2, and signal ES2 as shown in Figure 4. The waveforms of signals PS2 and PS3 are the same as those shown in Figure 4.

[0087] As shown in Figures 2 and 8, the emission control unit 102 generates a signal CS based on the signal PS1 received from the first timing control unit 101, and outputs the signal CS to the light emission unit 103 at a third output timing (time T5) which is later by time ΔT2 than the first output timing (time T2).

[0088] At time T6, the light-emitting unit 103 emits laser light LE2 based on the signal CS output from the emission control unit 102, with an emission light intensity LIe2 that is ΔLI1 lower than the emission light intensity LIe1 and a pulse width PW2 that is ΔPW1 wider than the pulse width PW1.

[0089] Hereafter, the distance D3 is calculated by the measurement unit 108, the reproduced distance D3a is calculated by the first determination unit 110, and the deterioration or malfunction of the distance measuring device 1 is determined by the first determination unit 110, in the same manner as described above.

[0090] (Third process) The third process involves delaying the output timing of signal CS by the delay time ΔT2' determined in the second process, and delaying the second output timing Tout (=T4) of signal PS3, which was adjusted in the first process, by the same delay time ΔT2'. This process determines the error between the rising edge time Tr of signal PS3 received by the AD conversion unit 106 and the detection time Td of laser light LR2 by the light receiving unit 104.

[0091] The third process will be explained below using Figures 2 and 9.

[0092] Figure 9 shows an example of the waveforms of various signals and laser light during the execution of the third process. In Figure 9, the dashed lines represent the waveforms of signal CS, laser light LE2, signal PS3, and signal ES2, as shown in Figure 4. The waveform of signal PS2 is the same as the waveform shown in Figure 4.

[0093] As shown in Figures 2 and 9, the second timing control unit 105 generates a signal PS2 and outputs the signal PS2 to the AD converter 106 at time T1. Time T1 can be set to any arbitrary time.

[0094] The first timing control unit 101 generates signal PS1 and outputs signal PS1 to the output control unit 102.

[0095] The emission control unit 102 generates a signal CS based on the signal PS1 received from the first timing control unit 101, and outputs the signal CS to the light emission unit 103 at a time T5' which is delayed by a delay time ΔT2' compared to the first output timing (time T2). Hereinafter, time T5' will also be referred to as the "fourth output timing".

[0096] The third timing control unit 107 generates the signal PS3 and outputs the signal PS3 to the AD conversion unit 106 at a time T7' which is delayed by a delay time ΔT2' compared to the second output timing (time T4) after adjustment by the first processing. Hereafter, time T7' will also be referred to as the "fifth output timing".

[0097] At time T6', the light-emitting unit 103 emits laser light LE2 with an emission light intensity Lie2 and pulse width PW1 that is ΔLI1 lower than the emission light intensity Lie1, based on the signal CS output from the emission control unit 102.

[0098] The light receiving unit 104 detects the laser light LR2 corresponding to the laser light LE2 reflected by the emission / receiving window 3. The light receiving unit 104 generates a signal ES2 by converting the laser light LR2 into an electrical signal and outputs the signal ES2 to the AD conversion unit 106.

[0099] The AD conversion unit 106 performs AD conversion on the signal ES2 received from the light receiving unit 104 based on the signal PS2 received from the second timing control unit 105. The AD conversion unit 106 outputs data DT2 corresponding to the AD converted signal ES2 to the measurement unit 108.

[0100] Furthermore, the AD conversion unit 106 performs AD conversion on the signal PS3 received from the third timing control unit 107 based on the signal PS2 received from the second timing control unit 105. The AD conversion unit 106 outputs data DT3 corresponding to the AD converted signal PS3 to the measurement unit 108.

[0101] The measurement unit 108 detects the peak portion of the signal ES2 based on the data DT2. In the example in Figure 9, the peak portion is detected at time Tp3'. The measurement unit 108 calculates the time Tp3' of the detected peak portion as the detection time Td of the laser light LR2. The measurement unit 108 calculates ToF based on the difference between the time origin T0 (=Tp2) and the detection time Td of the laser light LR2 reflected by the emission / receiving window 3. The measurement unit 108 calculates the distance D4 between the distance origin D0 (emission / receiving window 3) and the pseudo-distant object based on ToF and the velocity of the laser light LE2. That is, the measurement unit 108 calculates the distance D4 based on the time origin T0 and time Td. The measurement unit 108 transmits the data DT2, time Td, and distance D4 to the second determination unit 111.

[0102] Furthermore, the measurement unit 108 detects the peak portion of the signal PS3 based on the data DT3. In the example in Figure 9, the peak portion is detected at time Tp4. The measurement unit 108 calculates the time Tp4 of the detected peak portion as the rising edge time Tr of the signal PS3. Time Tp4 represents the correct value of the detection time Td of the laser light LR2. The measurement unit 108 calculates ToF based on the difference between the time origin T0 (=Tp2) and the rising edge time Tr of the signal PS3. The measurement unit 108 calculates the distance D5 between the distance origin D0 and the pseudo-distant object based on ToF and the speed of the laser light LE2. Distance D5 represents the correct value of the distance D4 between the distance origin D0 (emitting / receiving window 3) and the pseudo-distant object. The measurement unit 108 transmits time Tr and distance D5 to the second determination unit 111.

[0103] The second determination unit 111 compares time Tr and time Td and determines whether time Td (=Tp3') falls within a predetermined error range ERG2 (for example, an error rate ERT2 of about 5%) relative to time Tr (=Tp4). Figure 10 shows an example of the error range ERG2 used for the determination in the third process. In the example in Figure 10, the error range ERG2 includes the range from time ta to time Tr, and the range from time Tr to time tb. The error rate ERT2 is calculated, for example, by (|Tr-Td| / Tr) × 100. Note that the error rate ERT2 may be calculated by other methods.

[0104] The second determination unit 111 determines that distance D4 cannot be measured if time Td is not within the error range ERG2, that is, if no peak portion is detected near time Tp4 in the data DT2.

[0105] Because the rising edge of signal PS3 is free of distortion, the calculated rising edge time and distance D5 of signal PS3 are highly stable and have little variation. On the other hand, the detection time Td and distance D4 of laser light LR2 show greater variation when close to the detection limit distance. By comparing the rising edge time Tr of signal PS3 with the detection time Td of laser light LR2, more accurate results can be obtained.

[0106] Furthermore, the second determination unit 111 may determine that distance D4 cannot be measured if the amount of light LIr (value of signal ES2) of the laser beam LR2 in the data DT2 is lower than the threshold TH1. The threshold TH1 is, for example, the noise intensity. If it is lower than the threshold TH1, the rising edge portion indicating the detection time of the laser beam LR2 may be buried in noise.

[0107] Furthermore, the second determination unit 111 may determine that distance D4 cannot be measured if time Td is not within the error range ERG2 and the amount of light LIr received by the laser beam LR2 in data DT2 is lower than the threshold TH1.

[0108] If the second determination unit 111 determines that distance measurement is not possible at distance D4, it determines that the detectable limit distance is less than distance D4.

[0109] The process is repeated in the same manner as in Figure 9 (hereinafter, this repeated process will be referred to as the "second iteration"). Specifically, in the second iteration, the process is repeated m times (where m is an integer greater than or equal to 2) in the same manner as in Figure 9. That is, the measurement unit 108 calculates the detection time Td and the rise time Tr m times. The time Td calculated on the mth time is referred to as "time Td m It is also written as "Time Tr". The time Tr calculated on the mth time is called "Time Tr m It is also written as ". After the second iteration process is executed, the second determination unit 111 determines time Td m The detection efficiency DE is calculated based on the number of times CNT entered the error range ERG2. The detection efficiency DE is calculated, for example, by (CNT / m) × 100. That is, the detection efficiency DE is calculated based on time Td for m times. m This indicates the percentage of times CNT falls within the error range ERG2. Note that the detection efficiency DE may be calculated by other methods. The second determination unit 111 stores the detection efficiency DE in the storage mentioned above. This completes the second iteration process. The second iteration process is executed, for example, once a day.

[0110] Here, the second iterative process is executed once a day, and so far it has been executed for a total of n days (n times) (where n is an integer greater than or equal to 2), meaning that the second determination unit 111 has calculated the detection efficiency DE n times, and n detection efficiency DEs are stored in the storage mentioned above. The detection efficiency DE stored on the nth time is called "Detection Efficiency DE n It is written as "".

[0111] Figure 11 shows the relationship between the received light intensity LIr and the detection efficiency DE of the laser light LR2. In the example in Figure 11, the received light intensity LIr is represented as 100 when the detection efficiency DE is 100%. As shown in Figure 11, as the received light intensity LIr decreases, the detection efficiency DE also decreases. When the received light intensity LIr becomes LIr1 or less, the detection efficiency DE becomes 0.

[0112] Therefore, the second determination unit 111 determines whether the distance measuring device 1 is degraded or malfunctioning based on the n stored detection efficiency DEs. Specifically, the second determination unit 111 determines, for example, the detection efficiency DE calculated for the nth time. n The detection efficiency DE calculated on the (n-1)th attempt. n-1 Compare the following: Detection efficiency DE n The detection efficiency DE n-1 If the value is lower than this, the second determination unit 111 determines that the distance measuring device 1 is deteriorated or malfunctioning.

[0113] <1-2> Operation The diagnostic operation of the distance measuring device 1 will be explained using Figure 12. Figure 12 is a flowchart showing an example of the diagnostic operation of the distance measuring device 1 according to this embodiment. The diagnostic operation is an operation that performs a diagnostic function.

[0114] For example, the distance measuring device 1 performs a diagnostic operation when it is first started up each day. The diagnostic operation is performed once a day. The first start-up of the day is, for example, when the power to the transportation equipment (railway vehicle) is turned on. At this time, the power to the distance measuring device 1 is turned on, and with the position of the distance measuring device 1 unchanged, the distance measuring device 1 begins the diagnostic operation.

[0115] First, the distance measuring device 1 performs the first process as described above (S101). Next, the distance measuring device 1 performs the second process as described above (S102). Next, the distance measuring device 1 performs the third process as described above (S103). Once the third process is completed and there are no problems with the diagnostic results, the distance measuring function becomes operational, and the distance measuring device 1 performs the distance measuring operation.

[0116] Note that the first process does not have to be performed every time. Since the distance measuring device 1 stores the second output timing Tout in the storage mentioned above through the first process, the second and third processes may be executed based on the previous second output timing Tout. In this case, the diagnostic time can be shortened compared to when the first process is executed.

[0117] <1-3> Effects of the Embodiments The distance measuring device 1 according to this embodiment includes an emission control unit 102, a light-emitting unit 103, a reflective object (emission / receiving light window 3), a light-receiving unit 104, a third timing control unit 107, an AD conversion unit 106, a measurement unit 108, and an adjustment unit 109. The emission control unit 102, light-emitting unit 103, light-receiving unit 104, third timing control unit 107, AD conversion unit 106, measurement unit 108, and adjustment unit 109 perform the first process as described above.

[0118] In the first process, the output timing of signal PS3 is adjusted. Specifically, the output timing of signal PS3 is adjusted to the second output timing (=T4) so ​​that the detection time Td (=Tp2) of laser light LR2 and the rising edge time Tr (=Tp1) of signal PS3 coincide. This makes it possible to reproduce the detection time Td of laser light LR2 when signal CS is output at the first output timing (=T2) and laser light LE2 is emitted, using the rising edge time Tr of signal PS3. In addition, the detection time Td (=Tp2) of laser light LR2 is set as the reference time (time origin T0) for calculating ToF between it and the pseudo-distant object, and the position of the reflecting object is set as the reference position (distance origin D0) for calculating the distance between it and the pseudo-distant object. Therefore, according to this embodiment, by using the second output timing, time origin T0, and distance origin D0, it becomes possible to simulate the laser light reflected by the pseudo-distant object within the distance measuring device 1.

[0119] Furthermore, the distance measuring device 1 according to the embodiment further comprises a first determination unit 110. The emission control unit 102, light emission unit 103, light receiving unit 104, third timing control unit 107, AD conversion unit 106, measurement unit 108, and first determination unit 110 perform the second processing as described above.

[0120] In the second process, a laser beam LE2 is emitted with a delay of time ΔT2 (output timing of signal CS) and a lower emission intensity, and the distance D3 is calculated. The calculation of distance D3 is repeated multiple times, with time ΔT2 being increased by a constant time ΔT2a. This allows the reproducible distance D3a between the reflecting object and the pseudo-distant object to be calculated, and the delay time ΔT2' is determined. Therefore, according to this embodiment, it is possible to virtually reproducible the laser beam reflected by the pseudo-distant object within the distance measuring device 1.

[0121] The reproducible distance D3a is stored, for example, once a day, and the current reproducible distance D3a is compared with the previous reproducible distance D3a. If the current reproducible distance D3a is shorter than the previous reproducible distance D3a, it is determined that the distance measuring device 1 is degraded or malfunctioning. Therefore, according to this embodiment, the deterioration or malfunction of the distance measuring device 1 can be diagnosed while the position of the distance measuring device 1 is unchanged, that is, while the transportation equipment is stopped.

[0122] Furthermore, the distance measuring device 1 according to the embodiment further comprises a second determination unit 111. The emission control unit 102, light emission unit 103, light receiving unit 104, third timing control unit 107, AD conversion unit 106, measurement unit 108, and second determination unit 111 perform the third process as described above.

[0123] In the third process, the emission timing of the laser beam LE2 (output timing of signal CS) is delayed by a delay time ΔT2', and a laser beam LE2 with low emitted light intensity is emitted, and the detection time Td (=Tp3') and distance D4 of the laser beam LR2 are calculated. The signal PS3 is output later than the second output timing (=T4) by a delay time ΔT2', and the rising edge time Tr (=Tp4) and distance D5 of the signal PS3 are calculated. Therefore, according to this embodiment, it is possible to simulate the laser beam reflected by a simulated distant object inside the distance measuring device 1.

[0124] Furthermore, it is determined whether time Td (=Tp3') falls within the error range ERG2 relative to time Tr (=Tp4). If time Td does not fall within the error range ERG2, it is determined that distance D4 cannot be measured. The calculation of distance D4 is repeated multiple times. This allows the detection efficiency DE to be calculated.

[0125] The detection efficiency DE is stored, for example, once a day, and the current detection efficiency DE is compared with the previous detection efficiency DE. If the current detection efficiency DE is shorter than the previous detection efficiency DE, it is determined that the distance measuring device 1 is degraded or malfunctioning. Therefore, according to this embodiment, it is possible to diagnose the degradation or malfunction of the distance measuring device 1 while the position of the distance measuring device 1 is not changing, that is, while the transportation equipment is stopped.

[0126] <2> Modifications, etc. The distance measuring device 1 according to this embodiment can be modified as follows, for example.

[0127] <2-1> First variation A distance measuring device according to a first modification of the embodiment will be described. The distance measuring device 1A according to the first modification of the embodiment differs from the embodiment in that it uses a reflective object 16 to reflect the laser beam LE2. The following description will explain the differences from the embodiment.

[0128] <2-1-1> Configuration of the Rangefinder The configuration of the distance measuring device 1A will be explained using Figure 13. Figure 13 is a block diagram showing an example of the configuration of the distance measuring device 1A. As shown in Figure 13, the distance measuring device 1A includes, for example, a housing 2, an output / receiving window 3, a distance measuring control unit 11, a laser driver 12, a laser diode 13, a light sensor 14, an ADC 15, a reflective object 16, and mirrors 17 and 18.

[0129] The housing 2 houses the distance measuring control unit 11, laser driver 12, laser diode 13, optical sensor 14, ADC 15, reflective object 16, and mirrors 17 and 18.

[0130] The reflective object 16 is placed on the emission / receiving window 3 (the inner surface of the housing 2 of the emission / receiving window 3). The reflective object 16 has the function of reflecting the laser light emitted from the laser diode 13. The reflective object 16 is positioned at a predetermined distance from the laser diode 13. Furthermore, the reflective object 16 is placed in a location that does not affect the field of view of the emission / receiving window 3.

[0131] Mirrors 17 and 18 have reflective surfaces (mirror surfaces).

[0132] The laser light LR2 reflected by the reflective object 16 is reflected by the mirror 17, and then reflected again by the mirror 18.

[0133] The light sensor 14 detects the laser light LR2 that has been reflected by the reflective object 16, reflected by the mirror 17, and further reflected by the mirror 18. The light sensor 14 is positioned so that the laser light LR1 emitted from the laser diode 13 and reflected by the object OB outside the distance measuring device 1, and the laser light LR2 emitted from the laser diode 13 and reflected by the reflective object 16, as well as the mirrors 17 and 18, are incident on it.

[0134] The configuration other than the reflective object 16 and the mirrors 17 and 18 is the same as in the embodiment shown in Figure 1.

[0135] The functional configuration of the distance measuring device 1A is the same as that of the embodiment shown in Figure 2. The operation of the distance measuring device 1A is the same as that of the embodiment shown in Figure 12.

[0136] <2-1-2> Effects of the first modified example This modified example achieves the same effects as the embodiment.

[0137] <2-2> Second variation A distance measuring device according to a second modification of the embodiment will now be described. The distance measuring device 1B according to the second modification of the embodiment differs from the first modification of the embodiment in that the reflective object 16 is arranged on the inner wall of the housing 2. The following description will explain the differences from the first modification of the embodiment.

[0138] <2-2-1> Configuration of the Rangefinder The configuration of the distance measuring device 1B will be explained using Figure 14. Figure 14 is a block diagram showing an example of the configuration of the distance measuring device 1B. As shown in Figure 14, the distance measuring device 1B includes, for example, a housing 2, an output / receiving window 3, a distance measuring control unit 11, a laser driver 12, a laser diode 13, a light sensor 14, an ADC 15, a reflective object 16, and mirrors 17 and 18.

[0139] The reflective object 16 is placed on the inner wall of the housing 2. The reflective object 16 is positioned at a predetermined distance from the laser diode 13.

[0140] The laser light LR2 reflected by the reflective object 16 is reflected by the mirror 17, and then reflected again by the mirror 18.

[0141] The light sensor 14 detects the laser light LR2 that has been reflected by the reflective object 16, reflected by the mirror 17, and further reflected by the mirror 18. The light sensor 14 is positioned so that the laser light LR1 emitted from the laser diode 13 and reflected by the object OB outside the distance measuring device 1, and the laser light LR2 emitted from the laser diode 13 and reflected by the reflective object 16, as well as the mirrors 17 and 18, are incident on it.

[0142] Aside from the reflective object 16 and the mirrors 17 and 18, the configuration is the same as the first modified example of the embodiment shown in Figure 13.

[0143] The functional configuration of the distance measuring device 1B is the same as in the first modified embodiment. The operation of the distance measuring device 1B is the same as in the first modified embodiment.

[0144] <2-2-2> Effects of the second modified example This modified example achieves the same effects as the first modified example of the embodiment.

[0145] <2-3> Others The embodiments are not limited to the forms described above, and various modifications are possible.

[0146] Each of the processes described in each embodiment may be implemented by dedicated hardware. In each embodiment, there may be a mixture of processes performed by software and processes performed by hardware, or only one of them may be present.

[0147] The scanning method performed by the distance measuring device 1 is a raster scan, a multi-channel scan, a multi-channel raster scan, or an OPA (Optical Phased Array) method, etc.

[0148] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0149] 1, 1A, 1B... Distance measuring device, 2... Housing, 3... Light emission / receiving window, 11... Distance measuring control unit, 12... Laser driver, 13... Laser diode, 14... Optical sensor, 15... ADC, 101... First timing control unit, 102... Light emission control unit, 103... Light emission unit, 104... Light receiving unit, 105... Second timing control unit, 106... AD conversion unit, 107... Third timing control unit, 108... Measurement unit, 109... Adjustment unit, 110... First determination unit, 111... Second determination unit

Claims

1. A first control unit that outputs a first signal, A light-emitting unit that emits a first laser beam based on the first signal, A reflective object is placed inside the light-emitting unit at a predetermined distance from it, A light receiving unit that detects a second laser beam corresponding to the first laser beam reflected by the reflective object, A second control unit that outputs a second signal, An AD conversion unit that performs AD conversion on a third signal corresponding to the second laser light output from the light receiving unit and the second signal received from the second control unit, A measurement unit calculates a first detection time of the second laser light based on first data corresponding to the AD-converted third signal and calculates a first rising edge time of the second signal based on second data corresponding to the AD-converted second signal when the first signal and the second signal are output simultaneously at a first output timing and the first laser light is emitted with a first emission light intensity and a first pulse width, An adjustment unit adjusts the output timing of the second signal to the second output timing based on the first detection time and the first rising edge time. Equipped with, Ranging device.

2. The output timing of the second signal is adjusted to the second output timing such that the first detection time and the first rising edge time coincide. The distance measuring device according to claim 1.

3. The output timing of the second signal is adjusted to the second output timing such that the difference between the first detection time and the first rising edge time is minimized. The distance measuring device according to claim 1.

4. The adjustment unit sets the first detection time to the reference time for calculating the Time of Flight (TF) between the object and the pseudo-distant object. The distance measuring device according to claim 1.

5. The measurement unit, when the first signal is output at a third output timing that is one hour later than the first output timing, and the first laser light is emitted with a second emission light intensity and a first pulse width lower than the first emission light intensity, calculates a second detection time of the second laser light based on the first data, and calculates a first distance between the reflective object and the pseudo-distant object based on the reference time and the second detection time. The distance measuring device according to claim 4.

6. First judgment part Furthermore, The first time is set to (initial value + k × second time) (where k is a non-negative integer), The measurement unit performs the calculation of the first distance i times (where i is an integer of 2 or more), The first determination unit determines whether the first distance calculated on the (k+2)th time falls within the first error range. The distance measuring device according to claim 5.

7. The first error range is the error range for the sum of the first distance calculated on the (k+1)th time and the distance calculated based on the second time and the speed of the first laser light. The distance measuring device according to claim 6.

8. If the first distance calculated on the (k+2)th attempt does not fall within the first error range, the first determination unit calculates the first distance calculated on the (k+1)th attempt as the recall distance and determines (the initial value + (k+1) × the second time) as the delay time. The distance measuring device according to claim 6.

9. The first determination unit is, The calculation of the reproduction distance is performed j times (where j is an integer of 2 or more), If the calculated distance on the jth attempt is shorter than the calculated distance on the (j-1)th attempt, it is determined that the distance measuring device is deteriorated or malfunctioning. The distance measuring device according to claim 8.

10. The measurement unit, when the first signal is output at a third output timing that is one hour later than the first output timing, and the first laser light is emitted with a second emission light intensity lower than the first emission light intensity and a second pulse width wider than the first pulse width, calculates a second detection time of the second laser light based on the first data, and calculates a first distance between the reflective object and the pseudo-distant object based on the reference time and the second detection time. The distance measuring device according to claim 4.

11. Second judgment part Furthermore, The measurement unit, when the first signal is output at a fourth output timing that is delayed by the delay time compared to the first output timing, the second signal is output at a fifth output timing that is delayed by the delay time compared to the second output timing, and the first laser light is emitted with a second emission light intensity and a first pulse width lower than the first emission light intensity, calculates a third detection time of the second laser light based on the first data, calculates a second rising edge time of the second signal based on the second data, and calculates a second distance between the reflective object and the pseudo-distant object based on the reference time and the third detection time, The second determination unit determines whether the third detection time falls within the second error range with respect to the second rise time. The distance measuring device according to claim 8.

12. The second determination unit determines that the detectable limit distance is less than the second distance if the third detection time does not fall within the second error range. The distance measuring device according to claim 11.

13. The measurement unit calculates the third detection time and the second rise time m times (where m is an integer of 2 or more), The second determination unit calculates a detection efficiency that represents the ratio of the number of times the third detection time falls within the second error range out of m times. The distance measuring device according to claim 11.

14. The second determination unit described above is: The above detection efficiency calculation is performed n times (where n is an integer of 2 or more), If the detection efficiency calculated on the nth attempt is lower than the detection efficiency calculated on the (n-1)th attempt, it is determined that the distance measuring device is deteriorated or malfunctioning. The distance measuring device according to claim 13.

15. The second determination unit determines that the detectable limit distance is less than the second distance if the amount of light received by the second laser beam in the first data is lower than the first threshold. The distance measuring device according to claim 11.

16. The second determination unit determines that the detectable limit distance is less than the second distance if the third detection time does not fall within the second error range and the amount of light received by the second laser beam in the first data is lower than the first threshold. The distance measuring device according to claim 11.

17. The reflective object is a window that transmits the first laser light emitted from the light-emitting unit and the second laser light incident from the outside. The distance measuring device according to claim 1.

18. A window that transmits the first laser beam emitted from the light-emitting unit and the second laser beam incident from the outside. Furthermore, The reflective object is provided above the window, The distance measuring device according to claim 1.

19. cabinet Furthermore, The reflective object is provided on the inner wall of the housing, The distance measuring device according to claim 1.

20. The distance measuring device is a LiDAR. The distance measuring device according to claim 1.

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