Distance measuring device

Abstract

A distance measuring device is provided with: a light projecting unit that projects light from a light source onto a rotating or swinging mirror, and that projects the obtained scanning light onto an object; a light receiving unit that detects a change in brightness of the object caused by the scanning light; a distance information calculation unit that calculates the distance of the object on the basis of the scanning angle of the scanning light obtained from the time information of the brightness change of the object caused by the scanning light; and a direction changing unit that changes the direction of the scanning light such that the light receiving unit can detect reference light in a specific scanning direction, and the distance information calculation unit uses, as a reference time, time information of a brightness change generated in the light receiving unit by the reference light changed by the direction changing unit. The time information of the brightness change of the object is used as a relative value with respect to the reference time.

Description

Technical Field

[0001] An embodiment of the present invention relates to a distance measuring device. Background Art

[0002] As distance measurement methods based on triangulation using structured illumination, light projection methods such as the light section method, the phase shift method, and the spatial encoding method have been proposed. The light section method projects a strip of scanning light onto the object while scanning the object, captures the object from a shooting position different from the projection position, and calculates the distance to the object by triangulating the projection angle of the scanning light, the incident angle of the reflected light from the object onto the shooting surface, and the baseline length between the projection position and the shooting position (for example, refer to Patent Document 1). The projection angle of the scanning light is calculated, for example, based on the command value to the scanner and the detection time of the bright line of the reflected light appearing on the shooting surface, and the incident angle of the reflected light is calculated, for example, based on the incident position of the reflected light on the shooting surface. The light section method is considered to have good accuracy, but compared with the phase shift method, the spatial encoding method, etc., the number of images required for one measurement increases, so there is a problem that the measurement takes time.

[0003] In recent years, event-based image sensors have been proposed based on a concept different from that of general frame-based image sensors (for example, see Patent Documents 2 and 3). A frame-based image sensor opens and closes a shutter for a predetermined time to expose, thereby outputting a frame image at a predetermined period. In contrast, an event-based image sensor independently and asynchronously monitors each pixel at all times, and when an event (for example, a brightness change greater than a predetermined value) is detected, the position, time, and polarity (for example, whether it becomes brighter or darker) of the pixel with the event are output as event information. Compared to a frame-based image sensor, an event-based image sensor has the following characteristics: it only outputs event information on the basis of a wide dynamic range, and therefore is high-speed. Therefore, it is believed that by using an event-based image sensor, the light-cutting method can be accelerated.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-159988

[0007] Patent Document 2: Japanese Patent Application Publication No. 2021-068451

[0008] Patent Document 3: International Publication No. 2022 / 050279 Summary of the invention

[0009] Problems to be solved by the invention

[0010] While the distance measurement is accelerated by event-based image sensors, on the other hand, a technology capable of performing distance measurement with higher accuracy is also required. For example, when a rotating mirror is used as a scanner, a unit such as a photoelectric switch is sometimes used to detect a specific mirror angle, but the photoelectric switch has a certain measurement error based on its specifications, etc., and this measurement error sometimes becomes the main cause of deterioration of the distance measurement accuracy.

[0011] Means for solving problems

[0012] One method of the present disclosure is a distance measuring device, comprising a light projecting unit, which irradiates light from a light source onto a rotating or swinging reflector and projects the obtained scanning light onto an object; a light receiving unit, which detects a brightness change of the object caused by the scanning light; a distance information calculating unit, which calculates the distance of the object based on a scanning angle of the scanning light obtained from moment information of the brightness change of the object caused by the scanning light; and a direction changing unit, which changes the direction of the scanning light so that the light receiving unit can detect a reference light of a specific scanning direction, the distance information calculating unit uses the moment information of the brightness change caused by the reference light after being changed by the direction changing unit at the light receiving unit as a reference moment, and uses the moment information of the brightness change of the object as a relative value relative to the reference moment. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a plan view of a stereo camera showing the measurement principle of the stereo method.

[0014] Figure 2 This is a plan view of a light section system showing the measurement principle of the light section method.

[0015] Figure 3 This is a schematic perspective view of a three-dimensional measurement device using the light section method.

[0016] Figure 4 This is a block diagram of a distance measuring device according to one embodiment.

[0017] Figure 5 It is a schematic structural diagram of the distance measuring device of the first embodiment.

[0018] Figure 6 It is a schematic structural diagram of the distance measuring device of the second embodiment.

[0019] Figure 7 It is a schematic structural diagram of a distance measuring device according to a third embodiment. DETAILED DESCRIPTION

[0020] First, the measurement principle of the distance measuring device (here, a three-dimensional measuring device) of the present embodiment will be described. For ease of understanding, the measurement principles of the stereo method and the light section method will be described. Figure 1 This is a plan view of a stereo camera 1 showing the measurement principle of the stereo method. The stereo camera 1 has, for example, a left light receiving unit 2 and a right light receiving unit 3, which are equivalent to two cameras. The left light receiving unit 2 and the right light receiving unit 3 are, for example, arranged in equipotential parallelism. That is, the two light receiving units are separated by a baseline length B, the optical axes of the two light receiving units are arranged in parallel, the left light receiving surface 4 and the right light receiving surface 5 are arranged in a plane orthogonal to the two optical axes, and the x-direction and y-direction of each light receiving surface are oriented 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 in which a plurality of pixels are arranged one-dimensionally (for example, arranged only in the x-direction).

[0021] Here, if the position of the pixel on the left light receiving surface 4 where the image of the point P of the object existing in the object space appears is x1, and the position of the pixel on the right light receiving surface 5 is x r , then the parallax D between the left light receiving part 2 and the right light receiving part 3 is D = x1-x r If the origin of the XYZ coordinate system representing the three-dimensional space is placed at the right focus, and the focal distances of the two light receiving parts are respectively set to f, the distance Z to the point P of the object (the depth to the point P. The same applies below) is calculated according to the following formula 1.

[0022] [Mathematical formula 1]

[0023]

[0024] The baseline length B and the focal length f are constants determined by the design of the stereo camera 1. Therefore, if the image of point P on the right light-receiving surface 5 corresponding to the image of point P on the left light-receiving surface 4 can be detected through image processing such as pattern matching, the parallax D can be calculated based on the distance between the pixels of the two light-receiving surfaces, and the distance Z to point P of the object can be calculated.

[0025] The light-cutting system replaces the left light-receiving unit 2 of the stereo camera 1 with a light-projecting unit, for example. Figure 2 1 is a plan view of a light-section system 6 showing the measurement principle of the light-section method. Figure 3 2 is a schematic perspective view of the light cutting system 6. The light cutting system 6 includes a light projecting unit 7 corresponding to a projector, for example. The light projecting unit 7 projects light onto an object W located in the object space S while scanning, for example, a strip-shaped scanning light L1, and the light receiving unit 3 receives reflected light L2 reflected from the object W.

[0026] The light projection unit 7 includes: a light source 10 for scanning light L1, light projection optical systems 11 and 12 for shaping the light beam of the scanning light L1, and a scanning unit 13 for scanning the scanning light L1. The light source 10 is composed of, for example, a semiconductor laser, but is not limited thereto. For example, the light source 10 may also be composed of other light sources such as a solid laser (fiber laser, YAG laser, etc.), a gas laser (carbon dioxide laser, helium-neon laser, argon laser, etc.). The light projection optical systems 11 and 12 are composed of, for example, beam shaping lenses such as collimating lenses and cylindrical lenses. The scanning unit 13 is composed of, for example, a scanner including an electric scanner, an encoder, or a photoelectric sensor for detecting a specific scanning direction. The scanning light L1 is emitted from the light source 10, shaped into a slit light by the light projection optical systems 11 and 12, scanned by the scanning unit 13, and projected onto the object W.

[0027] The light receiving unit 3 includes a light receiving optical system 20 and an image sensor 21 for receiving the reflected light L2 from the object W. The light receiving optical system 20 includes, for example, a condenser lens. The image sensor 21 includes, for example, a plurality of pixels arranged in two dimensions, but is not limited thereto. For example, the image sensor 21 may also be composed of a plurality of pixels arranged in one dimension. The reflected light L2 reflected by the object W is condensed by the light receiving optical system 20 and received by the image sensor 21 to detect brightness changes.

[0028] Here, the projection starting point (rotation center) is located at the left focus of the stereo camera 1. If the projection angle relative to the left optical axis of the stereo camera 1 is set to θ, the pixel position x1 of the virtual left light receiving surface 4 of the projection unit 7 is calculated according to the following formula 2.

[0029] [Mathematical formula 2]

[0030] x l =f tanθ···Formula 2

[0031] In addition, if the projecting unit 7 rotates at a constant angular velocity ω from the projection starting point around the Y axis perpendicular to the XZ plane to irradiate the scanning light, the scanning light passes through the left optical axis at time t0 and projects onto point P of the object at a projection angle θ at time t. The projection angle θ is calculated according to the following formula 3.

[0032] [Mathematical formula 3]

[0033] θ=ω(t-t0) ···Formula 3

[0034] Therefore, if the pixel position x on the right light-receiving surface 5 r The reflected light at the point P receiving the slit light is expressed as in the following equation 4. Substituting equations 2 and 3 into equation 1, the distance Z to the point P of the object is calculated.

[0035] [Formula 4]

[0036]

[0037] The base line length B, the focal length f, the angular velocity ω, and the time t0 are constants determined by the design of the light-cutting system 6. Therefore, if the pixel position x of the right light-receiving surface 5 showing the image of the slit light is obtained, r By calculating the time t at which the image of the slit light is detected, the distance Z to the point P of the object is obtained.

[0038] However, the above-mentioned structure and measurement principle are only examples, and the design can be changed appropriately according to the design of the system structure, layout, etc. For example, the following system structure can also be adopted: the light-projecting unit 7 and the right light-receiving unit 3 are not arranged in parallel, and the left light-receiving unit 2 is not replaced by the light-projecting unit 7. In addition to the left light-receiving unit 2 and the right light-receiving unit 3, a light-projecting unit 7 is prepared, and the stereo method and the light-cutting method are combined. In addition, it is also possible to use a light beam-shaped point light or a block-shaped pattern light to project light onto the light-projecting unit 7 of the object instead of a strip-shaped slit light. Please note that the calculation method of the three-dimensional information also changes according to such a design change.

[0039] Hereinafter, the configuration of the distance measuring device according to the present embodiment will be described. Figure 4 The block diagram of a three-dimensional distance measuring device 30 is shown as an example. Although not shown in the figure, the distance measuring device 30 has, for example, a computer device including a processor, a memory, an input / output unit, etc. The processor has, for example, a CPU (central processing unit), the memory has, for example, a RAM (random access memory), a ROM (read only memory), etc., and the input / output unit inputs or outputs various data used or generated by the processor. The memory stores, for example, a program executed by the processor and various data used or generated by the processor.

[0040] The distance measuring device 30 includes: a light projecting unit 7 that projects light toward the object W while scanning the scanning light L1; a light receiving unit 3 that receives the reflected light L2 reflected by the object W through a plurality of pixels; a control unit 32 that controls the operation of the light projecting unit 7 and the light receiving unit 3; a deflecting unit 34 that deflects the light from the light projecting unit 7 so that it enters the light receiving unit 3 without passing through the object W; and a distance information calculating unit 36 ​​that calculates three-dimensional information of the object W by triangulation based on information output from the light receiving unit 3. The light projecting unit 7 corresponds to, for example, a projector, the light receiving unit 3 corresponds to, for example, a camera, and the control unit 32 and the distance information calculating unit 36 ​​correspond to, for example, a processor. As the scanning light L1, various lights such as slit light, spot light, and pattern light can be used.

[0041] The light projecting unit 7 may project a plurality of reference lights at predetermined projection angle intervals. The measurement time of the distance measuring device 30 is determined by the time required to scan the object W using the reference light. Therefore, the scanning speed is usually increased to shorten the measurement time, but the response speed of the light receiving unit 3 becomes a constraint. Therefore, by projecting a plurality of reference lights, the scanning speed can be increased under the constraint of the response speed of the light receiving unit 3 and the measurement time can be shortened.

[0042] The light receiving unit 3 has, for example, an image sensor in which a plurality of pixels are arranged two-dimensionally, but it may also be a common camera, or a line sensor in which a plurality of pixels are arranged one-dimensionally, and it may also be a single light detector (luminance meter, etc.) configured to detect light in a certain direction. A preferred example of the light receiving unit 3 is an event-based sensor, in which the light receiving unit 3 is composed of a plurality of pixels, and when the brightness change in each pixel is above a predetermined threshold, the position of the pixel, the time when the brightness change occurs, and the polarity indicating the direction of the brightness change are output as events. In the case of an event-based sensor, the light receiving unit 3 monitors each pixel independently and asynchronously at all times, and when a predetermined event (e.g., a predetermined brightness change) or above is detected, event information such as the position, time, and polarity (e.g., whether it becomes brighter or darker) of the pixel with the event is output. Alternatively, the sensor of the light receiving unit 3 may also be a general frame-based sensor. In the case of a frame-based sensor, the light receiving unit 3 opens and closes the shutter for a predetermined time to expose, thereby outputting a frame image at a predetermined period. The frame image includes, for example, a frame number, brightness information of each pixel, etc.

[0043] In the case where the sensor of the light receiving unit 3 is an event-based sensor, pixels with events (e.g., brightness changes above a predetermined value) capture reflected light from an object, and therefore, 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, time, and polarity of the pixel with brightness changes). The slit width of the scanning light and the spot diameter of the spot light are sometimes equivalent to multiple pixel sizes, and therefore, the distance measurement can also be performed by finding the intermediate time between the time when the pixel starts to brighten and the time when it ends to darken. On the other hand, in the case where the sensor of the light receiving unit 3 is a frame-based sensor, the distance information calculation unit 36 ​​detects the position and frame number (equivalent to the time) of the pixel with the maximum brightness based on multiple frame images output from the light receiving unit 3, and performs distance measurement based on these detection information.

[0044] Optionally, the distance information calculated by the distance information calculation unit 36 ​​may be output to an external device 40 such as a robot control device or a vehicle control device provided outside the distance measuring device 30. The output distance information can be used by the external device 40. For example, the external device 40 can perform position control, speed control, acceleration control, etc. based on the three-dimensional information in which the influence of the multi-reflected reference light is reduced.

[0045] (First embodiment)

[0046] Hereinafter, an embodiment of the distance measuring device 30 will be described, particularly focusing on the function of the direction changing unit 34 . Figure 5 1 is a schematic diagram of the distance measuring device 30 of the first embodiment. The distance measuring device 30 includes a housing 42, and a light projecting unit 7 and a light receiving unit 3 disposed in the housing 42. The light projecting unit 7 includes a light source 44 and a rotating reflector 46. The rotating reflector may rotate in one direction at a predetermined angular velocity or may swing at a predetermined angular velocity. The light from the light source 44 is reflected by the rotating reflector 46 and is directed toward the measuring object W as a scanning light L1 passing within a predetermined scanning direction range (scanning range) 52 relative to the object W, and is reflected by the object W and reaches the light receiving unit 3 as a reflected light L2. Here, on the premise that the rotating reflector rotates in one direction at a predetermined angular velocity or swings at a predetermined angular velocity, a method of providing a photoelectric switch (not shown) for detecting a specific angle of the rotating reflector 46 is considered. By using the photoelectric switch to detect a specific angle each time, the detection time is used as a reference, thereby suppressing the influence of changes caused by disturbances such as temporal changes in the rotational motion and the swinging motion and vibration, and obtaining the projection angle θ of the scanning light L1. However, the photoelectric switch has a certain detection error based on its specifications, etc., and this detection error may become the main reason for the deterioration of the distance measurement accuracy as the measurement time of the distance measuring device is accelerated. In addition, when using a photoelectric sensor, an interface circuit for receiving and transmitting the output of the photoelectric sensor is also required, which may also become the main reason for the cost increase of the device as a whole.

[0047] Therefore, the distance measuring device 30 of the first embodiment has a deflection unit 34 that uses the scanning light in a specific scanning direction from the light source 44 as the reference light L3 so that the light receiving unit 3 can detect the reference light 3 (part of it in most cases). Specifically, the angle of the rotating reflector 46 is such that the light from the light source 44 becomes aligned with the reference line 70 (equivalent to Figure 1 or Figure 2 The left optical axis) forms an angle θ P The reference light L3 is at an angle like the reference light L3 of the rotating mirror 46, the deflection unit 34 deflects the reference light L3 in the housing 42, and the light receiving unit 3 can detect (receive) the reference light L3. In the first embodiment, the deflection unit 34 has a fixed reflector 48 and a reflector 50 arranged in the housing 42, and the reference light L3 reflected by the rotating reflector 46 is reflected by the fixed reflector 48 toward the reflector 50, and is reflected by the reflector 50 to reach the light receiving unit 3.

[0048] Here, when the scanning light and the reference line 70 form θ P When the reference light L3 is detected by the light receiving unit 3 at tP According to the above formula 3, the projection angle θ is calculated by the following formula 3a. Figure 5 In, θ P represents the angle of the region located on the opposite side (negative side) of the scanning direction with respect to the reference line 70. However, please note that in this case, θ P Is a negative number.

[0049] [Formula 5]

[0050] θ=ω(tt P )+θ P Formula 3a

[0051] That is, the reference time t of the brightness change caused in the light receiving unit by the reference light L3 after the reference light L3 is changed by the changer 34 can be used. P The scanning angle θ is calculated by calculating the relative value of the time t of the brightness change caused by the reflected light L2 reflected by the object W, and the distance to the object can be calculated. In order to accurately determine the scanning angle θ, a reference time t is required. P Accurate. However, as mentioned above, the photoelectric switch has detection errors. In addition, when a motor with an electric scanner or encoder is used to constitute the scanning unit 13, a signal indicating that a specific angle has been detected can also be output from the motor control system, but usually these control systems operate in a dedicated control cycle, and the jitter error caused by the control cycle is superimposed on the output detection signal.

[0052] On the other hand, in the first embodiment, 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. In addition, since the light receiving unit that originally receives the reflected light L2 reflected by the object W is directly used, the time t of the equation 3a is P And t is the time when the brightness changes detected by the same light receiving unit, so it is possible to determine the scanning angle θ with high accuracy with very few error factors. This is also true in the second and third embodiments described later.

[0053] exist Figure 5 In the example, the reference light L3 is shown as light outside the scanning range 52, but for more accurate distance measurement, the scanning direction of the reference light L3 is preferably a direction adjacent to the scanning range 52. This is because if adjacent, the reference time t PThe closer the time t is to the scanning direction θ, the influence of the above-mentioned rotational motion, swinging motion, time-dependent changes, vibration and other disturbances are reduced, thereby, higher accuracy can be expected. Here, the adjacent direction refers to a state in which the distance measuring device does not cause obstacles in the distance measurement, and the distance measuring device 30 and the deflection unit 34 are physically constructed to be close to the scanning range 52, for example, the minimum angle between the reference light L3 and the scanning range 52 is within 15°, within 10°, and more preferably within 5°.

[0054] However, the scanning direction of the reference light L3 can also be set within the scanning range 52. For example, when the scanning light moves from the right side to the left side of the field of view of the light receiving unit (camera) 3, it is also possible to detect the pixels on the left side of the field of view as a specific scanning direction when the scanning light starts to observe on the right side of the field of view.

[0055] The reflector 50 is located within the field of view (angle of view) 54 of the light receiving unit (e.g., camera) 3, but is preferably arranged outside the angle of view 56 as the distance measuring device. In addition, the reflector 50 only needs to have an appropriate reflectivity so that the light receiving unit can detect it. For example, if the inner surface of the shell 42 has an appropriate reflectivity, it can also serve as the reflector 50. Usually, in order to prevent diffuse reflection, a dark non-woven fabric with low reflectivity is sometimes pasted on the inner surface of the shell 42, but the reflector 50 can be simply formed by not pasting the non-woven fabric on the part corresponding to the reflector 50. There is no special restriction on the fixed reflector 46. As long as the reference light L3 is directed toward the reflector 50, it can be any structure. For example, it can be a reflector (mirror) that can adjust the angle, or a part of the inner surface of the shell 42 can be set to a mirror shape.

[0056] Thus, in the first embodiment, by providing a redirecting portion 34 in the shell so that the light receiving portion 3 can detect the reference light L3 in a specific scanning direction, the angle θ of the scanning light when the brightness change of the object W is detected can be calculated with high accuracy, and for example, high-precision distance measurement with extremely short measuring time can be performed by effectively utilizing the high speed of the event-based image sensor.

[0057] (Second embodiment)

[0058] Figure 6 1 is a schematic diagram of the distance measuring device 30 of the second embodiment. In the second embodiment, the parts different from the first embodiment are mainly described, and the same or similar components as the first embodiment are denoted by the same or similar reference numerals, and detailed descriptions may be omitted.

[0059] In the second embodiment, a half mirror 64 is provided in the housing 42, and 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 reflector 46. In the first embodiment, the reflector 50 is arranged in the field of view (angle of view) 54 of the light receiving unit (for example, camera) 3, so that the angle of view 56 as the distance measuring device is limited. However, by using a half mirror, this limitation is eliminated, and the angle of view 56 as the distance measuring device can be set to a wide range that is the same as the field of view (angle of view) of the light receiving unit (for example, camera) 3. In addition, a fixed reflector 48 and a half mirror 64 may be arranged to have a plurality of reflectors that are arranged between the fixed reflector 48 and the half mirror 64. P The plate-like object 68 is formed by an opening (e.g., a pinhole) 66 through which the reference light L3 passes. Thus, it is possible to reduce the incidence of unnecessary light on the light receiving unit 3, and further, by making the light receiving unit (e.g., a camera) 3 receive light at an angle θ P The angle range is narrower, and the light receiving unit 3 can accurately detect the angle θ P Light (cannot receive light close to angle θ P light).

[0060] (Third Embodiment)

[0061] Figure 7 3 is a schematic diagram of the distance measuring device 30 of the third embodiment. In the third embodiment, the parts different from the first embodiment are mainly described, and the same or similar components as the first embodiment are denoted by the same or similar reference numerals, and detailed descriptions may be omitted.

[0062] In the third embodiment, the fixed reflector 48 is not used, and a light guide tube 60 having one end 61 through which the reference light L3 can enter is provided in the housing 42, and the light emitted from the other end 62 of the light guide tube 60 is reflected by the reflector 50 similar to the first embodiment and detected by the light receiving unit 3. Alternatively, the reflector 50 may be omitted, and the other end 62 of the light guide tube 60 may be arranged inside the camera angle of view 54 and at the angle of view 56, so that the light emitted from the other end 62 is directly received by the light receiving unit 3.

[0063] In the above-mentioned embodiment, slit light is used as scanning light, but the present disclosure is not limited to this. For example, a method of scanning a point light source by using a galvanometer mirror, MEMS, etc. to scan the field of view of a camera like a raster scan can also be applied to the present embodiment. The time for a point light source to scan the field of view increases, or a scanning mechanism in two directions is required, but on the other hand, the output of the light source can be made smaller than that of a slit light.

[0064] The first, second and third embodiments described above may be combined as appropriate. For example, the plate 68 having the opening 66 in the second embodiment may be applied to the first or third embodiment.

[0065] The embodiments of the present disclosure are described in detail, but the present disclosure is not limited to the above-mentioned embodiments. These embodiments can be variously added, replaced, changed, partially deleted, etc. without departing from the scope of the main idea of ​​the invention, or without departing from the content recorded in the scope of the patent protection requested and its equivalents. For example, in the above-mentioned embodiments, the order of each action and the order of each processing are shown as an example and are not limited to this. In addition, the same is true for the case where numerical values ​​or mathematical formulas are used in the description of the above-mentioned embodiments.

[0066] Explanation of symbols

[0067] 1 Stereo Camera

[0068] 2 Left light receiving part

[0069] 3 Right light receiving part

[0070] 4 Left light receiving surface

[0071] 5 Right light-receiving surface

[0072] 6 Light Cutting System

[0073] 7 Light projection part

[0074] 10 Light Source

[0075] 11.12 Light projection optical system

[0076] 13 Scanning Department

[0077] 20 Light receiving optical system

[0078] 21 Image Sensor

[0079] 30 Distance measuring device

[0080] 32 Control Unit

[0081] 34 Direction change unit

[0082] 36 Distance information calculation unit

[0083] 40 External devices

[0084] 42 Shell

[0085] 44 Light Source

[0086] 46 Rotating reflector

[0087] 48 Fixed reflector

[0088] 50 Reflector

[0089] 52 Scan range

[0090] 54 Camera View

[0091] 56 Installation View

[0092] 60 Light guide

[0093] 61, 62 end

[0094] 64 Half Mirror

[0095] 66 Opening

[0096] 68 Plates

[0097] B Baseline length

[0098] D Parallax

[0099] f focal distance

[0100] P Point of the object

[0101] W Object

[0102] The distance from Z to point P of the object

[0103] θ projection angle.

Claims

1. A distance measuring device, characterized in that: have: a light projecting unit that irradiates light from a light source onto a rotating or swinging reflective mirror and projects the obtained scanning light onto an object; a light receiving unit for detecting a change in brightness of the object caused by the scanning light; a distance information calculation unit that calculates the distance to the object based on a scanning angle of the scanning light obtained from time information of a brightness change of the object caused by the scanning light; as well as a direction changing unit configured to change the direction of the scanning light so that the light receiving unit can detect the reference light in a specific scanning direction, The distance information calculation unit uses time information of brightness change in the light receiving unit caused by the reference light changed by the change of direction unit as a reference time, and uses time information of brightness change of the object as a relative value with respect to the reference time.

2. The distance measuring device according to claim 1, characterized in that The light receiving unit is composed of a plurality of pixels, and when a brightness change in each pixel is greater than a predetermined threshold, the position of the pixel, the time when the brightness change occurs, and the polarity indicating the direction of the brightness change are output as events.

3. The distance measuring device according to claim 1 or 2, characterized in that: The scanning light is slit light.

4. The distance measuring device according to claim 1 or 2, characterized in that: The specific scanning direction is a direction adjacent to a scanning direction range for the object.

Images