Optical distance measuring device

Abstract

The light distance measuring device (100) includes: a light emitting section (40) that emits irradiation light IL; a light receiving section (60) that outputs a signal corresponding to the intensity of incident light including reflected light (RL, RLm, RLc) of the emitted irradiation light; a housing (80) that houses the light emitting section and the light receiving section; a distance measuring section (23) that performs distance measuring processing for measuring the distance to an object (OB) based on the intensity of the incident light; and an abnormality detection section (25) that performs abnormality detection processing for detecting an abnormality of the light emitting section using reflected light RL of the emitted irradiation light during a period in which the distance measuring processing is not performed.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from Japanese Patent Application No. 2020-085661 filed on May 15, 2020, and Japanese Patent Application No. 2021-066173 filed on April 9, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to an optical distance measuring device. Background Art

[0004] Known optical distance measuring devices include a light emitting unit that emits irradiated light and a light receiving unit that receives light including reflected light of the irradiated light. For example, Japanese Patent Application Laid-Open No. 2018-100880 discloses an optical distance measuring device including a light guide for guiding light used to detect a malfunction in an optical system to the light receiving unit.

[0005] However, Japanese Patent Application Laid-Open No. 2018-100880 includes a light guide for fault detection in addition to a light emitting unit and a light receiving unit, so the number of components of the optical distance measuring device increases, and there is a concern that the optical distance measuring device may become larger. Summary of the Invention

[0006] According to one embodiment of the present disclosure, an optical distance measuring device is provided. The optical distance measuring device includes: a light emitting unit that emits irradiation light; a light receiving unit that outputs a signal corresponding to the intensity of incident light including reflected light of the emitted irradiation light; a housing that accommodates the light emitting unit and the light receiving unit; a distance measuring unit that performs distance measurement processing to measure the distance to an object based on the intensity of the incident light; and an abnormality detection unit that performs abnormality detection processing to detect abnormalities in the light emitting unit using reflected light of the irradiation light emitted during a period when the distance measurement processing is not being performed.

[0007] According to this embodiment, the optical ranging device performs abnormality detection processing that detects abnormalities in the light-emitting unit using reflected light from the irradiated light emitted during a period when the ranging process is not being performed. Therefore, it is possible to detect abnormalities in the light-emitting unit without including a light-guiding unit for detecting abnormalities in the light-emitting unit. Therefore, it is possible to suppress an increase in the number of components in the optical ranging device and to prevent an increase in the size of the optical ranging device.

[0008] The present disclosure can be implemented in various forms, such as an abnormality detection device for an optical distance measuring device, an abnormality detection method for an optical distance measuring device, a computer program for implementing these devices and methods, and a storage medium storing such a computer program. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above-mentioned object and other objects, features and advantages of the present disclosure will become more apparent through the following detailed description with reference to the accompanying drawings.

[0010] Figure 1 is an explanatory diagram showing a schematic configuration of an optical distance measuring device as one embodiment of the present disclosure.

[0011] Figure 2 is a flowchart showing the processing sequence of the control processing executed in the optical ranging device,

[0012] Figure 3 is a timing diagram of the control process,

[0013] Figure 4 is an explanatory diagram for explaining areas divided using scanning angles.

[0014] Figure 5 This is a timing chart of the control process in the second embodiment. DETAILED DESCRIPTION

[0015] A. First embodiment:

[0016] Figure 1 The optical ranging device 100 shown detects the distance to the object OB by emitting irradiation light IL and receiving reflected light RL reflected by the object OB. The optical ranging device 100 is mounted on a vehicle for use, for example. In the present embodiment, the optical ranging device 100 is a LiDAR (Light Detection And Ranging). The optical ranging device 100 includes a light emitting unit 40, a light receiving unit 60, a scanning unit 50, and a control device 10. The optical ranging device 100 further includes a housing 80, and the light emitting unit 40, the light receiving unit 60, and the scanning unit 50 are accommodated in an internal space surrounded by the inner wall surface of the housing 80. The optical ranging device 100 has a predetermined scanning angle range NR, and performs emission of irradiation light IL based on the light emitting unit 40 and reception of reflected light RL based on the light receiving unit 60 in units of a unit scanning angle obtained by dividing the scanning angle range NR into a plurality of angles, thereby acquiring detection points as a whole in the scanning angle range NR, thereby achieving ranging. In addition, Figure 1 For ease of explanation, the schematic configuration of the optical distance measuring device 100 and the optical path are shown, but the optical path does not correspond to an actual optical path.

[0017] The light emitting unit 40 includes multiple light sources LD1, LD2, LD3, and LD4, which emit irradiation light IL per unit scan angle. Light sources LD1, LD2, LD3, and LD4 are infrared laser diodes that emit infrared laser light as irradiation light IL. The light emitting unit 40 drives the light sources LD1, LD2, LD3, and LD4 using a drive signal having a pulse drive waveform, thereby emitting infrared laser light, based on a light emission control signal input from the control device 10 that instructs the light sources LD1, LD2, LD3, and LD4 to emit light per unit scan angle.

[0018] The light receiving unit 60 includes a light receiving element array and a light receiving lens (not shown), and performs light receiving processing based on the reflected light RL of the irradiated light IL emitted from the light emitting unit 40, and outputs a detection signal representing the detection point. The light receiving element array is a flat-plate photosensor with multiple light receiving elements arranged two-dimensionally. For example, each light receiving element is composed of a SPAD (Single Photon Avalanche Diode) or other photodiodes. In addition, the term "light receiving pixel" is sometimes used as the minimum unit of light receiving processing, that is, the light receiving unit corresponding to the detection point. The light receiving unit refers to a light receiving pixel composed of a single light receiving element or a light receiving pixel composed of multiple light receiving elements. The light receiving unit 60 outputs the amount of incident light entering each light receiving pixel or an incident light intensity signal corresponding to the intensity of the incident light to the control device 10, using the unit scanning angle of light emitted by the light emitting unit 40 as a unit. The light receiving unit 60 can receive, in addition to the reflected light RL, ambient light (interference light) such as sunlight, light from streetlights, light from other vehicle lights, and light reflected from these lights by an object OB.

[0019] The scanning unit 50 reciprocates and scans the irradiation light IL emitted from the light emitting unit 40 within the scanning angle range NR. The scanning unit 50 includes a motor 52 and a scanning mirror 51. Specifically, the scanning unit 50 includes a mechanical movable portion that is driven by the motor 52 to perform a scanning operation on the scanning mirror 51.

[0020] The motor 52 is equipped with a motor driver (not shown). A rotation angle sensor (not shown) is provided on the motor 52 to detect the rotation angle of the motor 52. The motor driver receives a rotation angle signal from the rotation angle sensor and a rotation angle instruction signal output by the control device 10 to change the voltage applied to the motor 52 and control the rotation angle of the motor 52. The motor 52 is, for example, an ultrasonic motor, a brushless motor, or a brushed motor, and is equipped with a known mechanism for reciprocating within a scanning angle range NR. A scanning mirror 51 is attached to the motor 52.

[0021] The scanning mirror 51 is a reflector or mirror that scans the irradiation light IL emitted from the light emitting unit 40 in the horizontal direction. It is driven back and forth by the motor 52 to scan the scanning angle range NR in the horizontal direction. The scanning mirror 51 can also be a multi-faceted mirror such as a polygonal mirror, or a single-faceted mirror with a mechanism for swinging in the vertical direction, or other single-faceted mirrors that can swing in the vertical direction. The irradiation light IL is scanned according to the rotation angle of the scanning mirror 51. When the scanning mirror 51 is at a specified rotation angle, as shown in FIG. Figure 1 As shown by the solid line, the light is emitted to the measurement region MR through the window 82 provided in the housing 80. Figure 1 As shown by the dotted line, the irradiation light IL that is not emitted from the window portion 82 is reflected and scattered inside the housing 80. In the following description, the reflected light RL of the irradiation light IL after being reflected by the object OB in the measurement region MR is also referred to as "distance measurement reflected light RLm", and the internal scattered light of the irradiation light IL reflected in the housing 80 is referred to as "stray reflected light RLc". Figure 1 As shown by the solid line, the reflected light RLm for distance measurement enters the housing 80 from the measurement region MR through the window 82 and reaches the light receiving unit 60. Figure 1 As indicated by the dot-dash line, the stray reflected light RLc is reflected by the wall surface in the housing 80 and reaches the light receiving unit 60 .

[0022] The control device 10 includes a central processing unit (CPU) 20 as a computing unit, a memory 15 as a storage unit, and an input / output interface 11 as an input / output unit. The CPU 20, the memory 15, and the input / output interface 11 are connected via an internal bus in a manner capable of bidirectional communication. The memory 15 is configured to include a ROM and a RAM. The CPU 20 functions as a control unit 21, a distance measuring unit 23, and an abnormality detection unit 25 by expanding and executing a program (not shown) stored in the memory 15. In addition, the CPU 20 can be a single CPU, a plurality of CPUs that execute each program, or a multitasking CPU that can execute a plurality of programs simultaneously.

[0023] The control unit 21 controls the motor 52 , the light emitting unit 40 , and the light receiving unit 60 , thereby controlling the overall operation of the optical distance measuring device 100 .

[0024] The distance measuring unit 23 uses the detection signal input from the light receiving unit 60 to calculate the time (TOF: Time of Flight) from the start of irradiation of the irradiation light IL to the reception of the reflected light RLm for ranging, thereby measuring the distance to the object OB. In the following description, the measurement of the distance to the object OB by the distance measuring unit 23 is referred to as "ranging processing." In this embodiment, the ranging processing is performed when the irradiation light IL is scanned in one direction in the scanning angle range NR.

[0025] The abnormality detection unit 25 detects abnormalities in the light-emitting unit 40 (light sources LD1, LD2, LD3, and LD4). When not performing distance measurement processing, the abnormality detection unit 25 causes the light sources LD1, LD2, LD3, and LD4 to emit light at different times, detecting abnormalities in each of the light sources LD1, LD2, LD3, and LD4. Abnormality detection uses stray reflected light RLc. Stray reflected light RLc is light reflected at a very close distance from the light-emitting unit 40, and therefore has significantly higher intensity than ambient light or the distance-measuring reflected light RLm. Therefore, by using the signal value when the light-receiving unit 60 receives stray reflected light RLc, abnormalities in LD1, LD2, LD3, and LD4 can be detected with high accuracy. For example, abnormalities can be detected such as when the light intensity of each light source LD1, LD2, LD3, and LD4 is reduced compared to normal, or when each light source LD1, LD2, LD3, and LD4 is not emitting light. In the following description, the detection of abnormalities in the light-emitting unit 40 by the abnormality detection unit 25 is referred to as "abnormality detection processing." In this embodiment, the abnormality detection process is performed when the irradiation light IL is scanned back in one direction within the scanning angle range NR, that is, when the scanning angle scanned in one direction during the distance measurement process returns to the scanning angle before the distance measurement process is performed.

[0026] The light receiving unit 60, the light emitting unit 40, and the motor 52 are connected to the input / output interface 11 via control signal lines. The light emitting unit 40 receives an incident light intensity signal from the light receiving unit 60, and transmits a rotation angle instruction signal to the motor 52.

[0027] From the time the vehicle control system is started to the time it is stopped, or from the time the vehicle start switch is turned on to the time the start switch is turned off, the process is repeated at predetermined time intervals, for example, several 100ms. Figure 2 The control process shown in FIG. In step S10, the distance measurement unit 23 performs distance measurement processing. Specifically, the distance measurement unit 23 causes the light emitting unit 40 to emit irradiation light IL and causes the scanning unit 50 to scan the irradiation light IL in one direction. The distance measurement unit 23 calculates the TOF using the light reception signal of the reflected light RLm and measures the distance to the object OB.

[0028] In step S20, the abnormality detection unit 25 performs abnormality detection processing. In the abnormality detection processing of this embodiment, any one of the four light sources LD1, LD2, LD3, and LD4 is targeted for abnormality detection, and the presence of an abnormality in that light source is detected. Specifically, the abnormality detection unit 25 first causes only the light sources LD1, LD2, LD3, and LD4 targeted for abnormality detection to emit irradiation light IL, and then causes the scanning unit 50 to scan the irradiation light IL in the other direction of the scanning direction (the direction opposite to the direction in which the irradiation light IL was scanned during the distance measurement process). Next, the abnormality detection unit 25 obtains an incident light intensity signal of the stray reflected light RLc and compares the signal value of the incident light intensity signal with a predetermined reference value to detect the presence of an abnormality in the light source emitting the irradiation light IL. For example, if the signal value of the incident light intensity signal of the stray reflected light RLc is less than the predetermined reference value, it is detected that an abnormality has occurred in which the light intensity of the light source has decreased. Alternatively, if the value indicated by the incident light intensity signal of the stray reflected light RLc is 0 (zero), it is detected that the light source is in an abnormal state, with no light emission. In addition, if you use Figure 3 As will be described later, in order to detect the presence or absence of abnormalities in all four light sources LD1 , LD2 , LD3 , and LD4 , it is necessary to sequentially change the target of abnormality detection and perform abnormality detection processing four times.

[0029] exist Figure 3 In the timing diagram shown, the horizontal axis represents time, and the vertical axis represents the scanning angle of the irradiation light IL. If the control process begins at time t0, step S10 described above is executed, and the distance measurement process is performed during the period Ts from time t0 to time t1. During period Ts, the light source LD1 emits intermittent light in short pulses using duty cycle control. The duty cycle is, for example, less than 1%. At this time, the emitted irradiation light IL is scanned within a scanning angle range of -M[deg] to M[deg]. In this embodiment, period Ts is, for example, 100 milliseconds.

[0030] Once the distance measurement process is completed at time t1, step S20 described above is executed. During the period Ti from time t1 to time t2, abnormality detection processing for light source LD1 is performed. During period Ti, light source LD1 emits intermittent light in short pulses using duty cycle control. The duty cycle during abnormality detection processing can be smaller than the duty cycle during distance measurement processing. Light source LD, as a laser diode, has a light emission lifespan. By driving it at a duty cycle that emits the amount of light required for abnormality detection processing, the light emission lifespan of light source LD can be effectively utilized. At this time, irradiation light IL is emitted from light source LD1, the target of abnormality detection, while irradiation light IL is not emitted from the other light sources LD2, LD3, and LD4. The emitted irradiation light IL is scanned toward the other side of the scanning direction; specifically, it is scanned within a scanning angle range of M[deg] to -M[deg]. Therefore, the scanning angle during distance measurement processing is the same as the scanning angle during abnormality detection processing for light source LD1. In this embodiment, period Ti is, for example, 20 milliseconds. The period Ti is not limited to 20 milliseconds, and can be any time from 5 milliseconds to 30 milliseconds, for example. The period Ti is preferably shorter than the above-mentioned period Ts.

[0031] Once the abnormality detection process for light source LD1 is completed at time t2, distance measurement is performed during the period Ts from time t2 to time t3. Subsequently, abnormality detection for light source LD2 is performed during the period Ti from time t3 to time t4. Similar to the abnormality detection process for light source LD1, only irradiation light IL is emitted from light source LD2, the target of abnormality detection, and the emitted irradiation light IL is scanned within a scanning angle range of M[deg] to -M[deg].

[0032] Distance measurement is performed during the period Ts from time t4 to time t5, and then abnormality detection is performed for light source LD3 during the period Ti from time t5 to time t6. Illumination light IL is emitted only from light source LD3, the target of abnormality detection, and is scanned within a scanning angle range of M[deg] to -M[deg].

[0033] Distance measurement is performed during the period Ts from time t6 to time t7. Thereafter, abnormality detection processing for light source LD4 is performed during the period Ti from time t7 to time t8. Illumination light IL is emitted only from light source LD4, the target of abnormality detection, and is scanned within a scanning angle range of M[deg] to -M[deg]. Distance measurement and abnormality detection processing for each of light sources LD1, LD2, LD3, and LD4 are then repeated sequentially until the vehicle control system or the vehicle's start switch is turned off.

[0034] According to the optical distance measuring device 100 of this embodiment having the above configuration, an abnormality detection process is performed to detect an abnormality in the light emitting unit 40 using stray reflected light RLc reflected within the housing 80 by the irradiation light IL emitted during the period Ti when the distance measuring process is not being performed. Therefore, an abnormality in the light emitting unit 40 can be detected without including a light guide unit for detecting an abnormality in the light emitting unit 40. Therefore, an increase in the number of components of the optical distance measuring device 100 can be suppressed, and an increase in the size of the optical distance measuring device 100 can be suppressed.

[0035] The illumination light IL emitted during the distance measurement process and the illumination light IL emitted during the abnormality detection process scan within the same scanning angle range NR. Therefore, there is no need to switch the processes of the light emitting unit 40 and the scanning unit 50 between the distance measurement process and the abnormality detection process. This reduces the complexity of the control of the light emitting unit 40 and the scanning unit 50. Since the abnormality detection process is performed for each of the light sources LD1, LD2, LD3, and LD4 at different times, abnormalities in each of the light sources LD1, LD2, LD3, and LD4 can be detected with greater accuracy compared to a configuration in which the light sources LD1, LD2, LD3, and LD4 are all emitted at the same time and abnormalities in each light source LD1, LD2, LD3, and LD4 are detected. Specifically, during the distance measurement process, the light sources LD1 to LD4 are controlled to emit at intervals of several microseconds, making it difficult to identify the light source LD experiencing an abnormality. In contrast, during the abnormality detection process, the light sources LD1 to LD4 are controlled to emit individually during each abnormality detection process, making it easier to identify the light source LD experiencing an abnormality.

[0036] B. Second embodiment:

[0037] In the abnormality detection process of the first embodiment, the irradiation light IL emitted from each light source LD1, LD2, LD3, and LD4 scans within the same scanning angle range (M[deg] to -M[deg]). In contrast, in the second embodiment, the scanning angle range of the irradiation light IL varies for each light source LD1, LD2, LD3, and LD4. In this embodiment, the scanning angle range NR is divided into multiple regions using the scanning angle, and the irradiation light IL is emitted from a different light source LD1, LD2, LD3, and LD4 into each of the divided regions.

[0038] like Figure 4As shown, the scanning angle range NR is divided into four areas Ar1, Ar2, Ar3 and Ar4 according to the scanning angle. Specifically, the first area Ar1 is the area corresponding to the scanning angle range from M [deg] to N [deg] in the scanning angle range NR. The second area Ar2 is the area corresponding to the scanning angle range from N [deg] to zero [deg] in the scanning angle range NR. The third area Ar3 is the area corresponding to the scanning angle range from zero [deg] to -N [deg] in the scanning angle range NR. The fourth area Ar4 is the area corresponding to the scanning angle range from -N [deg] to -M [deg] in the scanning angle range NR. In addition, the scanning angles M and N can be set to arbitrary angles through experiments, etc.

[0039] The first area Ar1 is scanned with irradiation light IL emitted from the light source LD1. The second area Ar2 is scanned with irradiation light IL emitted from the light source LD2. The third area Ar3 is scanned with irradiation light IL emitted from the light source LD3. The fourth area Ar4 is scanned with irradiation light IL emitted from the light source LD4. Therefore, in the second embodiment, abnormalities in all the light sources LD1, LD2, LD3, and LD4 can be detected in a single return scan after the ranging process is executed.

[0040] exist Figure 5 In the timing diagram of the control process in the second embodiment shown, the horizontal axis represents time, and the vertical axis represents the scanning angle of the irradiation light IL. If the control process begins at time t0, the distance measurement process is performed during the period Ts until time t1. During this period, the irradiation light IL is scanned within a scanning angle range of -M [degrees] to M [degrees].

[0041] Once the distance measurement process is completed at time t1, abnormality detection processing is sequentially performed for each of the light sources LD1, LD2, LD3, and LD4 during the period Ti from time t1 to time t5. Specifically, abnormality detection processing is performed for light source LD1 from time t1 to time t2, abnormality detection is performed for light source LD2 from time t2 to time t3, abnormality detection is performed for light source LD3 from time t3 to time t4, and abnormality detection is performed for light source LD4 from time t4 to time t5. During the abnormality detection process for light source LD1, irradiation light IL is emitted from light source LD1, the target of abnormality detection, toward the first area Ar1, and is scanned from a position corresponding to a scanning angle M [deg] toward a position corresponding to a scanning angle N [deg]. Similar to the first embodiment, the abnormality detection unit 25 detects the presence of an abnormality in light source LD1 using the incident light intensity signal of the stray reflected light RLc.

[0042] In the abnormality detection process for light source LD2, irradiation light IL is emitted from the light source LD2, which is the target of abnormality detection, to the second area Ar2. The irradiation light IL is scanned from a position corresponding to a scanning angle N [deg] toward a position corresponding to a scanning angle 0 [deg], thereby detecting the presence of an abnormality in light source LD2. In the abnormality detection process for light source LD3, irradiation light IL is emitted from the light source LD3, which is the target of abnormality detection, to the third area Ar3. The irradiation light IL is scanned from a position corresponding to a scanning angle 0 [deg] toward a position corresponding to a scanning angle -N [deg], thereby detecting the presence of an abnormality in light source LD3. In the abnormality detection process for light source LD4, irradiation light IL is emitted from the light source LD4, which is the target of abnormality detection, to the fourth area Ar4. The irradiation light IL is scanned from a position corresponding to a scanning angle -N [deg] toward a position corresponding to a scanning angle -M [deg], thereby detecting the presence of an abnormality in light source LD4.

[0043] According to the optical ranging device of the second embodiment having the above configuration, the light emitting unit 40 uses different light sources LD1, LD2, LD3, and LD4 to emit irradiation light IL to each of the four areas Ar1, Ar2, Ar3, and Ar4 divided by the scanning angles during abnormality detection processing. Therefore, abnormalities of each of the light sources LD1, LD2, LD3, and LD4 can be detected in a single return scan. Therefore, the time required to detect abnormalities of each of the light sources LD1, LD2, LD3, and LD4 can be shortened.

[0044] C. Other implementation methods:

[0045] (1) In each of the above-mentioned embodiments, the optical ranging device 100 uses the stray reflected light RLc after the irradiation light IL emitted during the non-ranging period Ti is reflected in the housing 80 to perform abnormality detection processing of the light emitting unit 40, but the abnormality detection processing can also be performed using reflected light from the vehicle body, such as the roof or the engine hood, of a vehicle that is always at a constant distance from the optical ranging device 100.

[0046] (2) In each of the above-mentioned embodiments, during the abnormality detection process, the abnormality detection unit 25 directly uses the detection signal output from the light receiving unit 60, that is, the incident intensity signal. However, during the abnormality detection process, ambient light such as reflected light incident from the outside of the housing 80 due to the light emission of the light emitting unit 40 and reflected light incident from the outside of the housing 80 due to artificial light such as sunlight or street lamps also enters the light receiving unit 60. Therefore, in order to improve the accuracy of the abnormality detection process, the abnormality detection unit 25 may also perform a process of increasing the SN of the stray reflected light RLc, that is, a process of increasing the SN of the incident intensity signal corresponding to the stray reflected light RLc in the detection signal. As already described, the reflected light from the inside of the housing 80 close to the light emitting unit 40, that is, the stray reflected light RLc, has an extremely short TOF and a stronger incident intensity than the ambient light. Therefore, for example,

[0047] (a) The abnormality detection unit 25 may also apply a time filter to the detection signal from the light receiving unit 60, performing a time filtering process to extract the detection signal within the time range corresponding to the time of flight of the stray reflected light RLc, thereby increasing the SN of the incident intensity signal of the stray reflected light RLc. In this case, the incident intensity signal caused by ambient light with a longer time of flight than the stray reflected light RLc can be removed, thereby increasing the SN of the incident intensity signal of the stray reflected light RLc. Furthermore, the time filtering process may be performed either within the abnormality detection unit 25 or within the light receiving unit 60 based on a control signal from the abnormality detection unit 25.

[0048] (b) The abnormality detection unit 25 can also increase the SN of the incident intensity signal of the stray reflected light RLc by reducing the light receiving sensitivity of the light receiving unit 60, that is, by reducing the amount of signal amplification. The incident intensity signal of the stray reflected light RLc is sufficiently stronger than the incident intensity signal of the ambient light. Therefore, by reducing the light receiving sensitivity, the incident intensity signal caused by the ambient light is not received, resulting in an increase in the SN of the incident intensity signal of the stray reflected light RLc.

[0049] (c) Abnormality detection unit 25 may also reduce the light intensity at light emitting unit 40 and shorten the detection distance to increase the SN of the incident intensity signal of stray reflected light RLc. Since housing 80 is closer to light emitting unit 40 than to external objects, reducing the light intensity allows stray reflected light RLc from housing 80 to enter light receiving unit 60. Meanwhile, this prevents the light from reaching external objects located far from light emitting unit 40, or reduces the likelihood that reflected light from external objects, i.e., ambient light, will enter light receiving unit 60. This can increase the SN of the incident intensity signal of stray reflected light RLc.

[0050] (3) In each of the above embodiments, the optical ranging device 100 having a scanning unit 50 that performs mechanical scanning has been described. However, an optical ranging device having a non-mechanical scanning unit that does not have a mechanically movable portion may be used in place of the mechanical scanning unit 50. As a non-mechanical scanning unit, for example, a liquid crystal scanner, an optical phased array (OPA), or the like that does not have a movable portion and repeatedly scans the scanning angle range electronically can be used. Even when using these non-mechanical scanning units, since there is a non-ranging period, the above-mentioned abnormality detection process can be performed during the non-ranging period.

[0051] (4) In the above embodiments, the light emitting unit 40 is described as having four light sources LD1, LD2, LD3, and LD4 as an example of a plurality of light sources. However, the light source may be one, or the light emitting unit 40 may be provided with two, three, or five or more light sources.

[0052] (5) The control unit and other units and their methods described in the present disclosure may also be implemented by a dedicated computer provided by a processor programmed to execute one or more functions concretized by a computer program and a memory. Alternatively, the control unit and other units and their methods described in the present disclosure may also be implemented by a dedicated computer provided by a processor composed of one or more dedicated hardware logic circuits. Alternatively, the control unit and their methods described in the present disclosure may also be implemented by one or more dedicated computers composed of a combination of a processor programmed to execute one or more functions and a memory and a processor composed of one or more hardware logic circuits. In addition, the computer program may also be stored as an instruction executed by a computer in a non-migratable tangible recording medium that can be read by a computer.

[0053] The present disclosure is not limited to the above-mentioned embodiments and can be implemented in various configurations without departing from the scope of its main purpose. For example, in order to solve part or all of the above-mentioned problems, or to achieve part or all of the above-mentioned effects, the technical features in the embodiments corresponding to the technical features in the various methods described in the invention content column can be appropriately replaced or combined. In addition, if the technical feature is not described as an essential technical feature in this specification, it can be appropriately deleted.

Claims

1. An optical distance measuring device comprising: a light-emitting portion for emitting irradiation light; a light receiving unit that outputs a signal corresponding to the intensity of incident light including reflected light of the emitted irradiation light; a housing for accommodating the light emitting unit and the light receiving unit; a distance measuring unit that performs distance measurement processing for measuring the distance to the object based on the intensity of the incident light; and an abnormality detection unit that performs an abnormality detection process for detecting an abnormality in the light emitting unit using reflected light of the irradiation light emitted during a period when the distance measurement process is not being performed, It also includes a scanning unit that mechanically scans the emitted irradiation light back and forth within a predetermined scanning angle range. The irradiation light emitted in the distance measurement process and the irradiation light emitted in the abnormality detection process are both scanned over the same scanning angle range.

2. The optical distance measuring device according to claim 1, wherein: The abnormality detection unit detects abnormality of the light emitting unit using reflected light of the irradiation light reflected within the housing.

3. The optical distance measuring device according to claim 2, wherein: The abnormality detecting unit increases the SN of the reflected light reflected in the housing to detect abnormality of the light emitting unit.

4. An optical distance measuring device comprising: a light-emitting portion for emitting irradiation light; a light receiving unit that outputs a signal corresponding to the intensity of incident light including reflected light of the emitted irradiation light; a housing for accommodating the light emitting unit and the light receiving unit; a distance measuring unit that performs distance measurement processing for measuring the distance to the object based on the intensity of the incident light; and an abnormality detection unit that performs an abnormality detection process for detecting an abnormality in the light emitting unit using reflected light of the irradiation light emitted during a period when the distance measurement process is not being performed, It also includes a scanning unit that repeatedly scans the emitted irradiation light electronically within a predetermined scanning angle range. The irradiation light emitted in the distance measurement process and the irradiation light emitted in the abnormality detection process are both scanned over the same scanning angle range.

5. The optical distance measuring device according to claim 4, wherein: The abnormality detection unit detects abnormality of the light emitting unit using reflected light of the irradiation light reflected within the housing.

6. The optical distance measuring device according to claim 5, wherein: The abnormality detecting unit increases the SN of the reflected light reflected in the housing to detect abnormality of the light emitting unit.

7. An optical distance measuring device comprising: a light-emitting portion for emitting irradiation light; a light receiving unit that outputs a signal corresponding to the intensity of incident light including reflected light of the emitted irradiation light; a housing for accommodating the light emitting unit and the light receiving unit; a distance measuring unit that performs distance measurement processing for measuring the distance to the object based on the intensity of the incident light; and an abnormality detection unit that performs an abnormality detection process for detecting an abnormality in the light emitting unit using reflected light of the irradiation light emitted during a period when the distance measurement process is not being performed, The light emitting unit includes a plurality of light sources. The abnormality detection unit performs the abnormality detection process on each of the light sources at different times. Also features: a scanning unit configured to reciprocate the emitted irradiation light within a predetermined scanning angle range; and A control unit controls the scanning angle of the scanning unit. In the abnormality detection process, the light emitting unit uses a different light source to emit the irradiation light to each of the plurality of areas divided by the scanning angle.

8. The optical distance measuring device according to claim 7, wherein: The abnormality detection unit detects abnormality of the light emitting unit using reflected light of the irradiation light reflected within the housing.

9. The optical distance measuring device according to claim 8, wherein: The abnormality detecting unit increases the SN of the reflected light reflected in the housing to detect abnormality of the light emitting unit.

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