Distance measuring device

Abstract

This distance-measuring device comprises: a light projection unit to project light from a light source onto a rotating or oscillating mirror and project the resulting scan light onto an object; a light reception unit to detect any change in the object's luminance due to the scan light; a distance calculation unit to calculate the distance to the object based on the projection angle of the scan light, which is obtained from the time information regarding the change in the object's luminance due to the scan light; and a direction change unit to change the direction of the scan light to enable the light reception unit to detect reference light in a specific scan direction.The unit for calculating distances considers time information regarding a change in luminance generated in the light reception unit due to reference light, the direction of which has been changed by the direction change unit, as a reference time, and considers time information regarding a change in the object's luminance as a relative value in relation to the reference time.

Description

TECHNICAL AREA

[0001] The present invention relates to a device for distance measurement. BACKGROUND ART

[0002] As a method for distance measurement based on triangulation using structured light, a light projection method such as a light-slit method, a phase-shift method, and a spatial coding method have been proposed. In the light-slit method, when scanning an object, a band-shaped slit light is projected onto the object, the object is imaged from an imaging position different from a projection position, and the distance to the object is calculated by triangulation based on a projection angle of the slit light, an incident angle of the slit light on the imaging surface, and a baseline length between the light projection position and the imaging position (see, for example, Patent Literature 1). The projection angle of the slit light can be, for example,The angle of incidence of the slit light can be obtained from a command value to a scanner or the acquisition time of a bright line of slit light appearing on the imaging surface, and the angle of incidence of the slit light can be obtained from the incident position of the slit light on the imaging surface. The light-section method is considered highly accurate, but compared to the phase-shift method or the spatial coding method, the number of images required for a single measurement is larger, and therefore there is the problem that the measurement takes a long time.

[0003] In recent years, an event-based image sensor has been proposed, based on a concept different from general image-based image sensors (see, for example, Patent Literatures 2 and 3). The image-based image sensor outputs images at predetermined intervals by exposing them for a predetermined period of time by opening / closing a shutter. The event-based image sensor, on the other hand, monitors each pixel independently and asynchronously from one moment to the next. Then, when an event (e.g., a change in luminance exceeding a predetermined value) is detected, the position, timing, and polarity (e.g., whether it has become brighter or darker) of the pixel where the event occurred are output as event information. The event-based image sensor has a wider dynamic range than the image-based image sensor and is faster because it outputs only event information.Therefore, it is assumed that the use of the event-based image sensor contributes to accelerating the light-section method. [CITATION LIST][PATENT LITERATURE] [PTL 1] JP 2014-159988 A [PTL 2] JP 2021-068451 A [PTL 3] WO 2022 / 050279 A1 SUMMARY OF THE INVENTION [TECHNICAL PROBLEM]

[0004] While event-based image sensors, etc., can accelerate distance measurement, there is also a need for technology that enables highly accurate distance measurement. For example, when a rotating mirror is used as a scanner, a photoelectric sensor, etc., is employed to detect a specific angle of the mirror. However, a photoelectric sensor, due to its specifications, etc., has a certain measurement error, which can affect the accuracy of distance measurement. (SOLUTION OF THE PROBLEM)

[0005] One aspect of the present disclosure is a distance measuring device comprising: a light projection unit configured to irradiate light from a light source onto a rotating or oscillating mirror and project a received scanning light onto an object; a light reception unit configured to detect a change in the luminance of the object due to the scanning light;a distance calculation unit configured to calculate a distance to the object based on a projection angle of the scanning light calculated from time information regarding the change in luminance of the object due to the scanning light, and a direction changing unit configured to change a direction of the scanning light so that the light receiving unit can detect a reference light in a specific scanning direction, wherein the distance calculation unit is configured to determine the time information regarding the change in luminance generated in the light receiving unit due to the reference light whose direction has been changed by the direction changing unit as a reference time and determine the time information regarding the change in luminance of the object as a relative value from the reference time; BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a top view of a stereo camera showing the measuring principle of a stereo method. Fig. 2 is a plan view of a light-sectioning system showing a measuring principle of a light-sectioning method. Fig. 3 is a perspective view of a three-dimensional measuring device using the light-section method. Fig. 4 is a block diagram of a distance measuring device of an embodiment. Fig. 5 is a schematic configuration view of a distance measuring device according to a first example. Fig. 6 is a schematic configuration view of a distance measuring device according to a second example. Fig. 7 is a schematic configuration view of a distance measuring device according to a third example. DESCRIPTION OF THE EMBODIMENTS

[0006] First, the measurement principle of a three-dimensional measuring device of the present embodiment will be described. For a better understanding, the measurement principles of a stereo method and a light-section method will be described. Fig. Figure 1 is a plan view of a stereo camera 1 illustrating the measurement principle of the stereo method. The stereo camera 1 includes a left light-receiving unit 2 and a right light-receiving unit 3, which correspond to two cameras, for example. The left and right light-receiving units 2 and 3 are arranged equiparallel to each other, for example. That is, the two light-receiving units are separated by a length of the baseline B, the optical axes of the light-receiving units are arranged in parallel, a left light-receiving surface 4 and a right light-receiving surface 5 are arranged in a plane orthogonal to the two optical axes, so that the x and y directions of each light-receiving surface point in the same direction. Each light-receiving surface is, for example, an image sensor in which a plurality of pixels are arranged two-dimensionally, but may also be a line sensor, etc.in which a large number of pixels are arranged one-dimensionally (e.g. arranged only in the x-direction).

[0007] In this context, it is assumed that a position of a pixel on the left surface for light reception 4, onto which an image of a point P of an object existing in an object space is projected, is defined as x l is determined, and a position of a pixel on the right surface for light reception 5, onto which the image of the point P of the object is projected, as x r is determined, a disparity D between the left and right units for light reception 2 and 3 is (x ı - x r ) (D = x l - x r). Assuming that the origin of the XYZ coordinate system representing three-dimensional space is at a right focal point and the focal length of each unit for light reception is f, the distance Z to the point P of the object (the depth to the point P (hereinafter as above)) is given by the following equation 1. [Equation 1] Z=BƒD

[0008] The length of the baseline B and the focal length f are constants determined by the design of the stereo camera 1. Therefore, if the image of the point P on the right light-receiving surface 5, which corresponds to the image of the point P on the left light-receiving surface 4, can be acquired by image processing such as pattern matching, the inequality D can be obtained from a distance between the pixels of the light-receiving units, and then the distance Z to the point P of the object can be found.

[0009] The light section system is achieved, for example, by replacing the left light receiving unit 2 of the stereo camera 1 by a light projection unit. Fig. 2 is a plan view of the light section system 6 showing the measuring principle of the light section method, and Fig. Figure 3 is a schematic configuration view of the light-slitting system 6. The light-slitting system 6 includes a light projection unit 7, which corresponds, for example, to a projector. The light projection unit 7 projects a band-shaped scanning light L1 onto an object W located in an object space S while scanning the scanning light L1, and the right light reception unit 3 receives a reflected light L2 reflected from the object W.

[0010] The light projection unit 7 includes a light source 10 for the scanning light L1, light projection optical systems 11 and 12 configured to form a beam of the scanning light L1, and a scanning unit 13 configured to scan the scanning light L1. The light source 10 is, for example, a semiconductor laser, but is not limited thereto. The light source 10 may, for example, be another light source such as a solid-state laser (fiber laser, YAG laser, etc.) or a gas laser (carbon dioxide laser, helium-neon laser, argon laser, etc.). The light projection optical systems 11 and 12 are, for example, beam-shaping lenses such as collimating lenses or cylindrical lenses. The scanning unit 13 is, for example, B. from a galvano scanner or another scanner with an encoder or a photoelectric sensor to detect a specific scanning direction.The scanning light L1 is emitted by the light source 10, formed into a light slit by the light projection optical systems 11 and 12, scanned by the scanning unit 13 and projected onto the object W.

[0011] The light receiving unit 3 includes a light receiving optical system 20 configured to receive the reflected light L2 from the object W, and an image sensor 21. The light receiving optical system 20 includes, for example, a converging lens. The image sensor 21 includes, for example, a plurality of two-dimensionally arranged pixels, but is not limited thereto. For example, the image sensor 21 may consist of a plurality of one-dimensionally arranged pixels. The reflected light L2 reflected from the object W is converged by the light receiving optical system 20 and received by the image sensor 21, so that a change in the luminance of the reflected light is detected.

[0012] Assuming that the starting point of light projection (or a rotation center) is positioned at the left focal point of the stereo camera 1 and a projection angle from the left optical axis of the stereo camera 1 is θ, the pixel position x ı the left light receiving surface 4 of the light projection unit 7 is obtained by the following equation 2. [Equation 2] xi=ƒtan θ

[0013] Assuming that the light projection unit 7 irradiates the band-shaped scanning light from the light projection start point while rotating at a constant angular velocity ω around the Y axis perpendicular to the XZ plane, the scanning light passes through the left optical axis at a time t0, and the scanning light is projected onto the point P of the object at the projection angle θ at time t, the projection angle θ can be obtained by the following equation 3. [Equation 3] θ=ω(t−t0)

[0014] Assuming that the reflected light at point P of the slit light is at position x r of the pixel on the right surface for light reception 5, the distance Z to the point P of the object can be determined by substituting equations 2 and 3 into equation 1 as shown in the following equation 4. [Equation 4] Z=BƒD=Bƒƒ tan(ω(t−t0))−xr

[0015] The length of the base line B, the focal length f, the angular velocity ω and the time t0 are constants determined by the construction of the system for the light section 6. Therefore, the distance Z to the point P of the object can be determined by determining the position x r of the pixel on the right light receiving surface 5 onto which an image of the slit light is projected and the time t at which the image of the slit light is detected.

[0016] However, it should be noted that the above configuration and measurement principle are examples, and the design may be changed according to the system configuration and layout, etc. For example, the light projection unit 7 and the right light reception unit 3 may not be arranged equiparallel to each other. Instead of replacing the left light reception unit 2 with the light projection unit 7, the light projection unit 7 may be prepared in addition to the left and right light reception units 2 and 3 to use a system configuration that combines the stereo method and the section light method. Furthermore, the light projection unit 7 may be used to project a beam-shaped spot light or a block-box-shaped pattern light onto the object instead of the band-shaped slit light.It should be noted that the method of calculating three-dimensional information also varies depending on such design changes.

[0017] The configuration of a distance measuring device of one embodiment is explained below. Fig. 4 is a block diagram of an example of a three-dimensional distance measuring device 30. Although not shown, the distance measuring device 30 includes a computing device including a processor, a memory, and an input / output unit, etc. The processor includes, for example, a CPU (central processing unit), and the memory includes, for example, a RAM (random access memory) and a ROM (read-only memory). The input / output unit is configured to input or output various data used or generated by the processor. The memory is configured to store, for example, a program executed by the processor and various data used or generated by the processor.

[0018] The distance measuring device 30 includes the light projection unit 7 configured to project the scanning light L1 onto the object W while scanning the light, the light reception unit 3 configured to receive the reflected light L2 from the object W at a plurality of pixels, a control unit 32 configured to control the operation of the light projection unit 7 and the light reception unit 3, a direction change unit 34 configured to change a direction of the light from the light projection unit 7 so that the light is received by the light reception unit 3 without passing through the object W, and a distance information calculation unit 36 ​​configured to calculate three-dimensional information of the object W by triangulation to the object based on a projection angle of the scanning light.which is calculated from time information regarding the change in the object's luminance due to the scanning light; a direction-changing unit 34 that redirects the light from the light projection unit 7 without passing through the object W and causes it to impinge on the light reception unit 3; and a distance calculation unit 36 ​​that calculates three-dimensional information of the object W through triangulation based on the information output from the light reception unit 3. The light projection unit 7 corresponds, for example, to a projector; the light reception unit 3 corresponds, for example, to a camera; and the control unit 32 and the distance calculation unit 36 ​​correspond, for example, to a processor. Various types of light, such as slit light, spot light, and pattern light, can be used as the scanning light L1.

[0019] The light projection unit 7 can project a plurality of reference lights while maintaining a predetermined projection angle distance. Since the measurement time of the distance measuring device 30 is determined by the time required to scan the object W with the reference light, it is common practice to increase the scanning speed to shorten the measurement time. However, in such a case, the response speed of the light reception unit 3 becomes a limitation. Therefore, by projecting a plurality of reference lights, it is possible to shorten the measurement time while maintaining the scanning speed while maintaining the response speed of the light reception unit 3.

[0020] The light receiving unit 3 includes, for example, an image sensor in which a plurality of pixels are arranged two-dimensionally. However, the light receiving unit 3 may also be a conventional camera, a line sensor in which multiple pixels are arranged one-dimensionally, or a single light detector (e.g., a luminance meter) configured to detect light in a specific direction. A preferred example of the light receiving unit 3 is an event-based sensor. In this case, the light receiving unit 3 consists of a plurality of pixels, and when the amount of change in luminance at each pixel is equal to or greater than a predetermined threshold, the light receiving unit 3 outputs the position of the pixel, the time at which the change in luminance occurred, and the polarity indicating the direction of the change in luminance as an event.In the case of an event-based image sensor, the light receiving unit 3 monitors each pixel independently and asynchronously from one moment to the next. When the light receiving unit 3 detects a predetermined event or events (e.g., a luminance change of a predetermined value or more), the light receiving unit 3 outputs event information, including the position of the pixel where the event occurred, the time at which the event occurred, and the polarity (e.g., the pixel becomes brighter or darker), etc. Alternatively, the sensor of the light receiving unit 3 can also be a conventional image-based image sensor. In the case of an image-based image sensor, the light receiving unit 3 opens and closes a shutter for a predetermined exposure time, thereby outputting individual images at predetermined time intervals. The individual images contain, for example,Image numbers and luminance information for each pixel, etc.

[0021] When the sensor of the light receiving unit 3 is an event-based sensor, the pixel where the event (e.g., a luminance change of a predetermined value or more) has occurred detects the light reflected from the object, and thus the distance information calculation unit 36 ​​performs distance measurement based on the event information output from the light receiving unit 3 (e.g., the position of the pixel where the luminance changes, the timing of the luminance change, and the polarity). Since the slit width of the scanning light and the spot diameter of the spot light can correspond to the size of several pixels, the distance measurement can be performed by determining the intermediate point between the beginning of the brightening and the end of the darkening of the pixel.On the other hand, when the sensor of the light receiving unit 3 is a frame-based sensor, the distance information calculating unit 36 ​​performs distance measurement, detects the position of the pixel having the maximum luminance among the plurality of frame images output from the light receiving unit 3 and the frame number (corresponding to the time point), and performs the distance measurement based on the detected information.

[0022] Optionally, the distance information calculated by the distance information calculation unit 36 ​​can be output to an external device 40, such as a robot controller or a vehicle controller, provided outside the distance measurement device 30. The output distance information can be used by the external device 40, and the external device 40 can, for example, perform position control, speed control, and / or acceleration control, etc., based on the three-dimensional information in which the influence of the multiply reflected reference light is reduced. (First example)

[0023] An embodiment of the distance measuring device 30 is described below, with particular emphasis on the function of the direction change unit 34. Fig. 5 is a schematic configuration view of the distance measuring device 30 according to a first example. The distance measuring device 30 includes a housing 42 and the light projection unit 7 and the light reception unit 3 arranged in the housing 42. The light projection unit 7 includes a light source 44 and a rotating mirror 46. The rotating mirror can rotate in one direction at a predetermined angular velocity or oscillate at a predetermined angular velocity. The light from the light source 44 is reflected by the rotating mirror 46 and reaches the measurement object W as scanning light L1, passing through a predetermined scanning direction range (scanning area) 52 for the object W, being reflected by the object W, and reaching the light reception unit 3 as reflected light L2.Here, a method of providing a photoelectric switch (not shown) for detecting a specific angle of the rotating mirror 46 is considered under the assumption that the rotating mirror rotates in one direction at a predetermined angular velocity or oscillates at a predetermined angular velocity. By detecting a specific angle each time using the photoelectric switch and using the detection time as a reference, it is possible to suppress the influence of fluctuations due to temporal changes in the rotation or oscillation motion and disturbances such as vibration, and to obtain the projection angle θ of the scanning light L1. However, the photoelectric switch has a certain detection error due to its specifications, etc., which may lead to deterioration of the distance measurement accuracy as the measurement time of the distance measuring device increases.In addition, when using the photoelectric sensor, an interface circuit, etc. is required to transmit and receive the output of the photoelectric sensor, which may increase the cost of the entire device.

[0024] Therefore, the distance measuring device 30 according to the first example has the direction changing unit 34 configured to determine the scanning light from the light source 44 in a specific scanning direction as the reference light L3 and enable the light receiving unit 3 to detect the reference light L3 (in many cases, a part of it). In particular, when the angle of the rotating mirror 46 is such that the light from the light source 44 becomes the reference light L3 forming an angle θp with a reference line 70 (corresponding to the left optical axis in Fig. 1 or Fig. 2), the direction-changing unit 34 redirects the reference light L3 within the housing 42 so that the light-receiving unit 3 can detect (receive) the reference light L3. In the first example, the direction-changing unit 34 includes a fixed mirror 48 and a reflector 50 disposed within the housing 42, and the reference light L3 reflected by the rotating mirror 46 is reflected by the fixed mirror 48 to the reflector 50 and further reflected by the reflector 50 to reach the light-receiving unit 3.

[0025] When the scanning light forms the angle θp with the reference line 70 and is detected by the light receiving unit 3 as the reference light L3, the projection angle θ is calculated by the following equation 3a using the detection time t p at this time and the above equation 3. Note that in Fig. 5 θp indicates an angle in the area on the opposite side (negative side) of the scanning direction with respect to the reference line 70, but in such a case it should be noted that θ P is a negative value. [Equation 5] θ=ω(t−tP)+θP

[0026] That is, the projection angle θ can be calculated from the relative time between the reference time t P the luminance change occurring in the light receiving unit due to the reference light L3 deflected by the direction change unit 34 and the time t of the luminance change due to the reflected light L2 reflected by the object W, and the distance to the object can be calculated. To accurately determine the projection angle θ, it is necessary that the reference time t Pis accurate. However, as described above, the photoelectric sensor has a detection error. Furthermore, if the unit is configured for Scan 13 with a galvano scanner and a motor equipped with an encoder, it is possible to output a signal indicating that a specific angle has been detected by its motor control systems. However, these control systems typically operate with a specific control cycle, and a jitter error caused by the control cycle is superimposed on the output detection signal.

[0027] On the other hand, in the first example, the reference light L3 is detected by the light receiving unit 3, so the above-mentioned photoelectric switch and the detection signal from the photoelectric switch and the motor control system are not required. Furthermore, since the light receiving unit, which originally receives the light L2 reflected from the object W, is used unchanged, the times t Pand t in Equation 3a are the times of luminance change detected by the same light receiving unit. Therefore, it is possible to determine the projection angle θ with very few error factors and with high accuracy. This also applies to the second and third examples described below.

[0028] In the example of Fig. 5, the reference light L3 is shown as a light outside the scanning area 52, but for a more accurate distance measurement, it is preferable that the scanning direction of the reference light L3 is a direction adjacent to the scanning area 52. If it is adjacent, the reference time t Pand the time t of the projection angle θ, and the influence of fluctuations due to the above-mentioned temporal changes in the rotation and tilting operations and disturbances such as vibrations can be reduced, thus expecting even higher accuracy. In this regard, the direction adjacent to the scanning area means a state in which the distance measurement as a distance measuring device is not obstructed, and the reference light is so close to the scanning area 52 that the distance measuring device 30 and the direction changing unit 34 can be physically configured, which means, for example, that the minimum angle formed by the reference light L3 and the scanning area 52 is within 15°, within 10°, and preferably within 5°.

[0029] However, the scanning direction of the reference light L3 may be within the scanning range 52. For example, when the scanning light moves from the right to the left side of the field of view of the light receiving unit (camera) 3, it is also possible to recognize a direction toward a pixel on the left side of the field of view as a specific scanning direction at the time the scanning light begins to appear on the right side of the field of view.

[0030] The reflector 50 is preferably arranged within a field of view (angle of view) 54 of the light receiving unit (e.g., camera) 3, but outside a viewing angle of the distance measuring device 56. The reflector 50 only needs to have a suitable reflectance so that the light receiving unit can detect the light. For example, if an inner surface of the housing 42 has a suitable reflectance, the inner surface can also serve as the reflector 50. Normally, a dark nonwoven fabric with low reflectance is attached to the inner surface of the housing 42 to prevent diffuse reflection, but the reflector 50 can be easily formed by not attaching a nonwoven fabric to a portion corresponding to the reflector 50. There are no particular restrictions on the fixed mirror 46, and any type can be used as long as it can direct the reference light L3 onto the reflector 50.The mirror 46 may, for example, be an angle-adjustable mirror or a part of the inner surface of the housing 42 which is formed as a mirror-like surface.

[0031] In this way, in the first example, by providing the direction changing unit 34 inside the housing so that the light receiving unit 3 can detect the reference light L3 in the specific scanning direction, it is possible to determine the angle θ of the scanning light with high accuracy when detecting the change in the luminance of the object W. This makes it possible to perform highly accurate distance measurement with an extremely short measurement time, for example, by utilizing the high speed of the event-based image sensor. (Second example)

[0032] Fig. 6 is a schematic configuration view of a distance measuring device 30 according to a second example. In the second example, components different from those of the first example are mainly described, and the same or similar reference numerals are used for the same or similar components as in the first example, and a detailed description is omitted.

[0033] In the second example, a half mirror 64 is provided in the housing 42 so that the light receiving unit 3 can receive (detect) both the reflected light L2 from the object W and the reference light L3 from the fixed mirror 46. In the first example, the reflector 50 is arranged within the field of view (angle of view) 54 of the light receiving unit (e.g., camera) 3, so that the field of view 56 of the distance measuring device is limited. However, by using the half mirror, this limitation is not imposed, and the field of view 56 of the distance measuring device can be set to a wide range identical to the field of view (angle of view) of the light receiving unit (e.g., camera) 3. Furthermore, a plate-shaped element 68 with an opening (e.g., a pinhole) 66 can be arranged between the fixed mirror 48 and the half mirror 64, through which only the reference light L3 passes at an angle θ. Pcan pass through. This can reduce the incidence of unnecessary light into the light receiving unit 3. Furthermore, the light receiving unit 3 can be made more efficient by narrowing the angular range of the angle θ received by the light receiving unit (e.g. camera) 3 P the light at angle θ P accurately (in other words, it cannot detect light close to the angle θ P received). (Third example)

[0034] Fig. 7 is a schematic configuration view of a distance measuring device 30 according to a third example. In the third example, components different from those of the first example are mainly described, and the same or similar reference numerals are used for the same or similar components as in the first example, and a detailed description is omitted.

[0035] In the third example, instead of the fixed mirror 48, a light guide tube 60 having one end 61 through which the reference light L3 can enter is provided within the housing 42, so that light emitted from the other end 62 of the light guide tube 60 is reflected by the reflector 50 and detected by the light receiving unit 3, similar to the first example. Alternatively, instead of the reflector 50, the other end 62 of the light guide tube 60 can be arranged within the viewing angle of the camera 54 and the viewing angle of the device 56, so that the light emitted from the other end 62 is directly received by the light receiving unit 3.

[0036] In the above embodiment, a slit light is used as the scanning light, but the present disclosure is not limited as such. For example, a method for scanning a point light source, such as scanning a camera's field of view in a raster scan using a galvano mirror or MEMS, can also be applied to the present examples. Although the point light source increases the time required to scan the field of view and requires a two-way scanning mechanism, the power of the point light source can be lower than that of a slit light.

[0037] The first, second, and third examples described above can be combined as needed. For example, the plate 68 with the opening 66 in the second example can be applied to the first or third example.

[0038] Although the various embodiments are described herein, it should be noted that the present invention is not limited to the above-mentioned embodiments and various modifications can be made within the scope of the claims. REFERENCE SYMBOL LIST 1 stereo camera 2 Left unit for light reception 3 Right unit for light reception 4 Left surface for light reception 5 Right surface for light reception (surface for light reception) 6 System for light sectioning 7 Light projection unit 10 Light source 11, 12 Optical system for light projection 13 Unit for scanning 20 Optical system for light reception 21 image sensor 30 Distance measuring device 32 Control unit 34 Unit for changing direction 36 Unit for calculating distances 40 External device 42 housings 44 Light source 46 rotating mirrors 48 fixed mirror 50 reflector 52 scan area 54 Camera angle 56 Viewing angle of the device 60 light guide tube 61, 62 End 64 half mirrors 66 Opening 68 plate B Length of the baseline D Inequality f focal length W Object Z Distance to point P of the object θ projection angle QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2014-159988 A

[0003] JP 2021-068451 A

[0003] WO 2022 / 050279 A1

[0003]

Claims

[1] A distance measuring device comprising: a light projection unit configured to project light from a light source onto a rotating or oscillating mirror and project a received scanning light onto an object; a light receiving unit configured to detect a change in the luminance of the object due to the scanning light; a distance information calculation unit configured to calculate a distance to the object based on a projection angle of the scanning light calculated from time information regarding the change in the luminance of the object due to the scanning light; and a direction changing unit configured to change a direction of the scanning light so that the light receiving unit can detect a reference light in a specific scanning direction, wherein the distance information calculation unit is configured to determine the time information regarding the change in luminance generated in the light receiving unit due to the reference light whose direction was changed by the direction changing unit as a reference time, and determine the time information regarding the change in luminance of the object as a relative value from the reference time. [2] The distance measuring device according to claim 1, wherein the light receiving unit is composed of a plurality of pixels and is configured to output, when an amount of change in luminance in each pixel is equal to or greater than a predetermined threshold, a position of the pixel, a timing at which the change in luminance occurs, and a polarity indicating a direction of the change in luminance as an event. [3] The distance measuring device according to claim 1 or 2, wherein the scanning light is a slit light. [4] The distance measuring device according to claim 1 or 2, wherein the specific scanning direction is a direction adjacent to a range of scanning directions to the object.

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