Ranging device

Abstract

The present invention improves ranging performance in a mechanical ranging device.　This ranging device (100) is provided with an emission-side mirror (222), a light-emitting unit (120), a light-receiving-side mirror (221), a light-receiving unit (130), and a ranging calculation unit (150). The emission-side mirror (222) can rotate about a predetermined rotation shaft (224). The light-emitting unit (120) emits laser light to the emission-side mirror (222). The light-receiving-side mirror (221) can rotate about the rotation shaft (224) together with the emission-side mirror (222), and the distance between the light-receiving-side mirror (221) and the rotation shaft is different from that between the emission-side mirror (222) and the rotation shaft. The light-receiving unit (130) receives the laser light reflected by the light-receiving-side mirror (221). The ranging calculation unit (150) calculates a distance on the basis of the signal from the light-receiving unit (130).

Description

Distance measuring device

[0001] This technology relates to a distance measuring device. More specifically, it relates to a distance measuring device that measures distance while scanning laser light.

[0002] Conventionally, in fields such as autonomous driving, LiDAR (Light Detection and Ranging) has been used to measure the distance to an object. For example, a mechanical LiDAR that rotates a mirror inside the device by an actuator has been proposed (see, for example, Patent Document 1).

[0003] Japanese Unexamined Patent Application Publication No. 2024-020940

[0004] In the above conventional technology, by using a mechanical method, scanning at a wider rotation angle is achieved compared to the MEMS (Micro Electro Mechanical Systems) method. However, when the mirror on the light emitting side and the mirror on the light receiving side are arranged in a V shape and rotated by a mechanical method, the laser light from the light emitting side is reflected inside the housing and enters the light receiving side, and the distance measuring performance may deteriorate particularly for objects at close range.

[0005] This technology was created in view of such a situation, and aims to improve the distance measuring performance in a mechanical distance measuring device.

[0006] This technology was made to solve the above problems. Its first aspect is a distance measuring device including an irradiation side mirror rotatable around a predetermined rotation axis, a light emitting unit that irradiates the irradiation side mirror with laser light, a light receiving side mirror rotatable around the rotation axis together with the irradiation side mirror and having a different distance from the rotation axis than the irradiation side mirror, a light receiving unit that receives the laser light reflected by the light receiving side mirror, and a distance measuring arithmetic unit that calculates the distance based on a signal from the light receiving unit. This enables the detection of objects at close range and brings about the effect of improving the distance measuring performance.

[0007] Furthermore, in this first aspect, the distance from the illuminating mirror to the rotation axis may be shorter than the distance from the light-receiving mirror to the rotation axis. This has the effect of shifting the light-emitting part inward.

[0008] Furthermore, in this first aspect, the end face of the illuminating mirror may be in contact with one of the two surfaces of the light-receiving mirror. This eliminates the gap between the illuminating mirror and the light-receiving mirror.

[0009] Furthermore, in this first aspect, a first gap component may be provided, which is positioned between the illuminating mirror and the light-receiving mirror. This eliminates the gap between the illuminating mirror and the light-receiving mirror.

[0010] Furthermore, in this first aspect, the first gap component may be bonded to the illuminating mirror and the light-receiving mirror. This eliminates the gap between the illuminating mirror and the light-receiving mirror.

[0011] Furthermore, in this first aspect, the device may further include a mirror holder that holds the illuminating mirror and the light-receiving mirror in a V-shape, a base that rotatably holds the mirror holder around the rotation axis, and a second gap component positioned between the mirror holder and the base. This eliminates the gap between the mirror holder and the base.

[0012] Furthermore, in this first aspect, the light-receiving mirror may be provided with a protrusion, and this protrusion may be bonded to the back surface of the illuminating mirror. This eliminates the gap between the light-receiving mirror and the illuminating mirror.

[0013] Furthermore, in this first aspect, the illuminating mirror may be provided with a protrusion, and this protrusion may be bonded to the back surface of the light-receiving mirror. This eliminates the gap between the illuminating mirror and the light-receiving mirror.

[0014] Furthermore, in this first aspect, the distance from the illuminating mirror to the rotation axis may be longer than the distance from the light-receiving mirror to the rotation axis. This has the effect of shifting the light-receiving part inward.

[0015] Furthermore, the second aspect of this technology is a distance measuring device comprising: an irradiating mirror rotatable around a predetermined axis of rotation; a light-emitting unit that irradiates the irradiating mirror with laser light; a light-receiving mirror that is rotatable together with the irradiating mirror around the axis of rotation and whose size in the direction parallel to the mirror surface is smaller than that of the irradiating mirror; a light-receiving unit that receives the laser light reflected by the light-receiving mirror; and a distance-measuring calculation unit that calculates the distance based on the signal from the light-receiving unit. This enables the detection of nearby objects and improves distance-measuring performance.

[0016] Furthermore, a third aspect of this technology is a distance measuring device comprising an optical window, a pair of mirrors rotatable around a predetermined axis of rotation, a light-emitting unit that irradiates laser light onto one of the pair of mirrors, a light-receiving unit that receives the laser light reflected by the other of the pair of mirrors, a distance-measuring calculation unit that calculates the distance based on the signal from the light-receiving unit, and a light-shielding component positioned between the optical window and the pair of mirrors. This enables the detection of nearby objects and improves distance-measuring performance.

[0017] This is a block diagram showing an example configuration of a distance measuring device in the first embodiment of this technology. This is an example of an overall view of a distance measuring device in the first embodiment of this technology. This is an example of a top view of a V-shaped oscillating mirror in the first embodiment of this technology. This is an example of a top view of a V-shaped oscillating mirror in the initial state in the first embodiment of this technology. This is an example of a V-shaped oscillating mirror with rotation angles of -30° and +30° in the first embodiment of this technology. This is an example of a top view of a V-shaped oscillating mirror in a comparative example. This is a diagram showing an example of the trajectory of a laser beam in the first embodiment of this technology. This is a diagram showing an example of the position of a folding mirror in the first embodiment of this technology. This is an example of a top view of a V-shaped oscillating mirror in the second embodiment of this technology. This is a diagram showing an example of the trajectory of a laser beam in the second embodiment of this technology. This is an example of a V-shaped oscillating mirror with rotation angles of -30° and +30° in the second embodiment of this technology. This is an example of a top view of a V-shaped oscillating mirror in the third embodiment of this technology. This is an example of a top view of a V-shaped oscillating mirror in the fourth embodiment of this technology. This is an example of a top view of a V-shaped oscillating mirror in the fifth embodiment of this technology. This is a diagram showing an example of a stray light trajectory in the first embodiment of this technology. This is an example of a top view of a V-shaped oscillating mirror in the sixth embodiment of this technology. This is a diagram showing an example of a gap component in the sixth embodiment of this technology. This is a diagram showing another example of a gap component in the sixth embodiment of this technology. This is an example of a top view of a V-shaped oscillating mirror in a modified version of the sixth embodiment of this technology. This is another example of a V-shaped oscillating mirror in a modified version of the sixth embodiment of this technology.

[0018] The following describes the embodiments for implementing this technology. The description will proceed in the following order: 1. First embodiment (example with the irradiating mirror shifted to the rear) 2. Second embodiment (example with an elongated irradiating mirror) 3. Third embodiment (example with the irradiating mirror shifted to the rear, and its end face in contact with the back surface of the light-receiving mirror) 4. Fourth embodiment (example with the light-receiving mirror shifted to the rear) 5. Fifth embodiment (example with a light-shielding component placed between the pair of mirrors and the optical window) 6. Sixth embodiment (example with the irradiating mirror shifted to the rear and a gap component placed)

[0019] <1. First Embodiment> [Example of Distance Measuring Device Configuration] Figure 1 is a block diagram showing an example configuration of a distance measuring device 100 in the first embodiment of the present technology. This distance measuring device 100 is a device that functions as a LiDAR and includes an optical window 110, a scanning unit 200, a light-emitting unit 120, a light-receiving unit 130, a control unit 140, a distance measurement calculation unit 150, and an external interface 160.

[0020] The external interface 160 transmits and receives data to and from an external host 400. This external interface 160 receives, for example, various setting data and control data from the host 400 and supplies it to the control unit 140. The external interface 160 also receives measurement data from the distance measurement calculation unit 150 and transmits it to the host 400.

[0021] The control unit 140 operates the light-emitting unit 120 and the light-receiving unit 130 in a synchronous manner. For example, the control unit 140 controls the light-emitting unit 120 in synchronization with a predetermined timing signal to emit laser light. The control unit 140 also controls the light-receiving unit 130 in synchronization with the same timing signal to receive the reflected laser light.

[0022] The light-emitting unit 120 generates laser light, such as infrared light, according to the control unit 140, and irradiates the scanning unit 200. The thick solid line in the figure indicates the irradiated laser light.

[0023] The scanning unit 200 scans the laser beam from the light-emitting unit 120 within a certain range. The laser beam from the scanning unit 200 is irradiated through the optical window 110 and reflected by the object to be measured 300, etc. The scanning unit 200 receives the reflected laser beam through the optical window 110 and guides it to the light-receiving unit 130. The dashed line in the figure represents the laser beam reflected by the object to be measured 300, etc. In addition to the laser beam, ambient light may also be incident on the scanning unit 200. The dotted line in the figure represents ambient light.

[0024] The light-receiving unit 130 receives laser light from the scanning unit 200 in accordance with the control of the control unit 140. This light-receiving unit 130 has multiple pixels (not shown), and each pixel receives laser light. The light-receiving unit 130 generates a pulse signal for each pixel in response to the reception of laser light and supplies it to the distance measurement calculation unit 150.

[0025] The distance measurement calculation unit 150 calculates the distance to an object such as the object to be measured 300 for each pixel based on the pulse signal from the light receiving unit 130. For example, the distance is calculated using the Time of Flight (TOF) method. The distance measurement calculation unit 150 generates measurement data indicating the distance for each pixel and supplies it to the external interface 160.

[0026] Figure 2 is an example of an overall view of the distance measuring device 100 in the first embodiment of this technology. A light-emitting lens 121 and a semiconductor laser light source 122 are arranged in the light-emitting unit 120, and a light-receiving lens 131 and a line sensor 132 are arranged in the light-receiving unit 130. A folding mirror 210 and a V-shaped oscillating mirror 220 are arranged in the scanning unit 200.

[0027] The V-shaped oscillating mirror 220 is an optical component in which a pair of mirrors connected in a V-shape are arranged to rotate around a predetermined axis of rotation. The axis parallel to this axis of rotation is referred to as the "Z-axis".

[0028] The semiconductor laser light source 122 emits a line-shaped laser beam, and the projection lens 121 focuses the laser beam and guides it to the irradiating side of the pair of mirrors in the V-shaped oscillating mirror 220. Furthermore, the direction in which the laser beam enters the V-shaped oscillating mirror 220, as viewed from the Z-axis, is defined as the "X-axis." The axis perpendicular to the X-axis and Z-axis is defined as the "Y-axis." As viewed from the X-axis and Y-axis, the laser beam is a line-shaped beam of light along the Z-axis.

[0029] The laser light reflected by the irradiating mirror is directed at the object to be measured, 300, etc. The laser light reflected by the object being irradiated is then reflected by the receiving mirror and the folding mirror 210 within the V-shaped oscillating mirror 220. This reflected light is focused by the receiving lens 131 and guided to the line sensor 132.

[0030] The line sensor 132 has a predetermined number of lines arranged, with multiple pixels arranged in the Z-axis direction forming one line. Each pixel has a photodetector such as a SPAD (Single-Photon Avalanche Diode) or a transistor, and receives reflected light in synchronization with the irradiation timing of the irradiated light, generating a pulse signal. The line sensor 132 and the subsequent distance measurement calculation unit 150 (not shown) are provided on, for example, a single semiconductor chip.

[0031] The distance measurement calculation unit 150 determines the round-trip time from the laser beam irradiation timing to the light reception timing indicated by the pulse signal using a TDC (Time-to-Digital Converter) or similar method, and calculates the distance for each pixel from that round-trip time. This method of directly measuring the round-trip time of light is called the dToF (direct Time of Flight) method.

[0032] Furthermore, the distance measurement calculation unit 150 can also use the iToF (indirect ToF) method instead of the dToF method. Alternatively, the FMCW (Frequency Modulated Continuous Wave) method can be used instead of the ToF method.

[0033] Furthermore, the control unit 140 can drive an actuator (not shown) to rotate the V-shaped oscillating mirror 220 around a predetermined axis of rotation. This axis of rotation extends along the physical vertical direction (in other words, the Z-axis direction), and if the direction perpendicular to this vertical direction is defined as the left-right direction, the rotation of the V-shaped oscillating mirror 220 causes the laser beam to be scanned from side to side.

[0034] [Example of V-shaped oscillating mirror configuration] Figure 3 is an example of a top view of a V-shaped oscillating mirror 220 in the first embodiment of this technology. This V-shaped oscillating mirror 220 comprises a light-receiving mirror 221, an illumination-side mirror 222, a mirror holder 223, a rotation axis 224, and a base 225.

[0035] The light-receiving mirror 221 reflects the laser light from the optical window 110 back towards the mirror 210. Viewed from the Z-axis direction, the cross-section of the light-receiving mirror 221 is rectangular, and its length (in other words, the direction parallel to the mirror surface) is denoted as L.

[0036] The irradiating mirror 222 reflects the laser light from the light-emitting unit 120 toward the optical window 110. Viewed from the Z-axis direction, the cross-section of the irradiating mirror 222 is rectangular, and its length is L, the same as that of the receiving mirror 221.

[0037] The mirror holder 223 holds the light-receiving mirror 221 and the illumination-side mirror 222 in a V-shape when viewed from the Z-axis direction. When viewed from the Z-axis direction, the angle between these mirrors is, for example, 90 degrees. In the mirror holder 223, if the distance from the light-receiving mirror 221 to the rotation axis 224 is d1 and the distance from the illumination-side mirror 222 to the rotation axis 224 is d2, then d1 is greater than d2. In other words, the illumination-side mirror 222 is positioned shifted towards the rear side of the distance measuring device 100 relative to the light-receiving mirror 221. This shift creates a slight gap between one end of the light-receiving mirror 221 and one end of the illumination-side mirror 222 at the base of the V-shape.

[0038] The base 225 holds the mirror holder 223 so that it can rotate around the axis of rotation. The mirror holder 223 can be rotated both clockwise and counterclockwise. The initial rotation angle is set to 0 degrees. The maximum value of the rotation angle when rotating clockwise is -R (where R is a real number), and the maximum value of the rotation angle when rotating counterclockwise is +R. The value of R is, for example, 30 degrees.

[0039] As described above, the illuminating mirror 222 can rotate around the axis of rotation at a rotation angle from -R to +R. The receiving mirror 221 can also rotate around the axis of rotation at a rotation angle from -R to +R together with the illuminating mirror 222, and the distance between it and the axis of rotation 224 is longer than that between it and the illuminating mirror 222.

[0040] As mentioned above, the light-emitting unit 120 irradiates the irradiation-side mirror 222 with laser light, and the light-receiving unit 130 receives the laser light reflected by the light-receiving mirror 221 and the reflection mirror 210. The distance-measuring calculation unit 150 calculates the distance based on the pulse signal from the light-receiving unit 130.

[0041] Figure 4 is a top view showing an example of the V-shaped oscillating mirror 220 in its initial state in the first embodiment of this technology. In the initial state, the angle between the light-receiving mirror 221 and the Y-axis is, for example, 45 degrees, and the angle between the irradiating mirror 222 and the Y-axis is also 45 degrees. The laser light from the light-emitting unit 120 is bent at a right angle by the irradiating mirror 222 and irradiated onto the object. The laser light reflected by the object is bent at a right angle by the light-receiving mirror 221 and incident on the folding mirror 210. The laser light is bent at a right angle again by the folding mirror 210 and incident on the light-receiving unit 130. The white arrows in the figure indicate the laser light. Also, Y2 is the Y-coordinate of the representative position (center position, etc.) of the folding mirror 210 and the light-receiving mirror 221, respectively.

[0042] FIG. 5 is a top view showing an example of the V-shaped rocking mirror 220 with a rotation angle of -30° and +30° in the first embodiment of the present technology. In the figure, a is a top view showing an example of the V-shaped rocking mirror 220 with a rotation angle of -30°. In the figure, b is a top view showing an example of the V-shaped rocking mirror 220 with a rotation angle of +30°.

[0043] As illustrated in a in the figure, the distance measuring device 100 can rotate the light receiving side mirror 221 and the irradiation side mirror 222 by up to 30 degrees in the clockwise direction while remaining in a V shape. Also, as illustrated in b in the figure, the distance measuring device 100 can rotate the light receiving side mirror 221 and the irradiation side mirror 222 by up to 30 degrees in the counterclockwise direction while remaining in a V shape. The reflection angle of the reflected light changes according to the rotation angle.

[0044] Here, as illustrated in FIG. 6, a V-shaped rocking mirror 220 in which the distance from the light receiving side mirror 221 to the rotation axis 224 is the same as the distance from the irradiation side mirror 222 to the rotation axis 224 is assumed as a comparative example.

[0045] Since the V-shaped rocking mirror 220 rotates, a slight gap is provided between the optical window 110 and the V-shaped rocking mirror 220. The laser light from the light emitting unit 120 at the coordinate Y0 may pass through the gap, be reflected by the optical window 110, and enter the light receiving side as stray light. In this case, the light receiving unit 130 outputs a pulse signal at a timing as if there is an object at a very short distance. Also, the laser light reflected by an object at a very short distance outside the optical window 110 and the laser light reflected inside the optical window 110 (i.e., stray light) overlap, and it becomes impossible to distinguish them. Therefore, in the comparative example, an object at a short distance cannot be detected, and the distance measuring performance deteriorates.

[0046] In contrast, in the first embodiment, as described above, the distance from the light receiving side mirror 221 to the rotation axis 224 is made longer than the distance from the irradiation side mirror 222 to the rotation axis 224. In other words, the irradiation side mirror 222 is shifted to the back side.

[0047] As illustrated in FIG. 7, when the irradiation-side mirror 222 is shifted to the back side, the position of the light-emitting unit 120 on the Y-axis can also be shifted to the back side of Y0 by the shifted amount and set as Y1. Thereby, it is possible to prevent the laser light (stray light) reflected by the optical window 110 from entering the light-receiving side. As a result, it becomes possible to detect an object at a short distance, and the ranging performance can be improved.

[0048] In addition, as illustrated in FIG. 8, the representative position of the folding mirror 210 can also be shifted to the back side of the representative position Y2 of the light-receiving-side mirror 221 and set as Y3. Thereby, compared with the case where the folding mirror 210 is not shifted, it is possible to more effectively prevent the laser light reflected by the optical window 110 from entering the light-receiving side.

[0049] As described above, according to the first embodiment of the present technology, since the distance from the light-receiving-side mirror 221 to the rotation axis 224 is made longer than the distance from the irradiation-side mirror 222 to the rotation axis 224, the light-emitting unit 120 can be shifted to the back side by that amount. Thereby, it is possible to prevent the laser light reflected by the optical window 110 from entering the light-receiving side, and particularly improve the ranging performance for an object at a short distance.

[0050] <2. Second Embodiment> In the above-described first embodiment, the irradiation-side mirror 222 is shifted to the back side. However, in this arrangement, a gap is generated between one end of the light-receiving-side mirror 221 and one end of the irradiation-side mirror 222 at the base of the V shape. Then, there is a possibility that the laser light from the irradiation side enters the light-receiving side through the gap. The distance measuring device 100 in this second embodiment is different from the first embodiment in that the irradiation-side mirror 222 is made longer than the light-receiving-side mirror 221.

[0051] FIG. 9 is an example of a top view of the V-shaped swing mirror 220 in the second embodiment of the present technology. In the second embodiment, both the distance from the light-receiving-side mirror 221 to the rotation axis 224 and the distance from the irradiation-side mirror 222 to the rotation axis 224 are d. Therefore, no gap is generated between one end of the light-receiving-side mirror 221 and one end of the irradiation-side mirror 222 at the base of the V shape.

[0052] Furthermore, when viewed from the Z-axis direction, the size of the light-receiving mirror 221 in the direction parallel to the mirror surface is L1, and the size of the illuminating mirror 222 in the direction parallel to the mirror surface is L2, which is greater than L1. In other words, the size of the light-receiving mirror 221 is smaller than that of the illuminating mirror 222.

[0053] As illustrated in Figure 10, increasing the size of the illuminating mirror 222 allows the position of the light-emitting unit 120 on the Y-axis to be shifted inward by that amount. If the position of the light-emitting unit 120 when the receiving mirror 221 and the illuminating mirror 222 are the same size is Y0, then increasing the size of the illuminating mirror 222 allows the position of the light-emitting unit 120 to be shifted to Y1, which is further inward than Y0. This prevents laser light (stray light) reflected by the optical window 110 from entering the receiving side, thereby improving the distance measurement performance.

[0054] However, as illustrated in Figure 11a, in the second embodiment, in order to avoid one end of the illumination-side mirror 222 hitting the base 225 when rotated clockwise at the maximum angle, it is necessary to increase the size of the base 225 in the Y-axis direction. The line segments with arrows at both ends in the figure indicate portions that are larger than those in the first embodiment.

[0055] Furthermore, as illustrated in figure b, in order to avoid one end of the illuminating mirror 222 hitting the light-emitting unit 120 when rotated clockwise at the maximum angle, it is necessary to keep the light-emitting unit 120 sufficiently far from the mirror on the X axis.

[0056] Therefore, in the second embodiment, the size of the scanning unit 200 may be larger compared to the first embodiment. Furthermore, as the size of the illumination-side mirror 222 increases, the torque required for its rotation increases, which may lead to an increase in the size of the actuator and an increase in power consumption.

[0057] Thus, according to the second embodiment of this technology, since the size of the irradiating mirror 222 is made larger than that of the receiving mirror 221, the light-emitting unit 120 can be shifted to the back. This prevents the laser light reflected by the optical window 110 from entering the receiving side, and improves the distance measurement performance, especially for objects at close range.

[0058] <3. Third Embodiment> In the first embodiment described above, a gap was created at the base of the V-shape between one end of the light-receiving mirror 221 and one end of the irradiation-side mirror 222. In this configuration, there is a risk that laser light from the irradiation side may enter the light-receiving side through this gap. The distance measuring device 100 in this third embodiment differs from the first embodiment in that the end face of the irradiation-side mirror 222 is positioned in contact with the back surface of the light-receiving mirror 221, thereby eliminating the gap.

[0059] Figure 12 is an example of a top view of a V-shaped oscillating mirror 220 in a third embodiment of this technology. Of the two sides of the light-receiving mirror 221, the side that is not the mirror surface is designated as the back surface.

[0060] In the third embodiment, the irradiating mirror 222 is positioned shifted to the rearward side on the Y-axis. Furthermore, the irradiating mirror 222 is positioned shifted toward the light-receiving side on the X-axis until its end face contacts the back surface of the light-receiving mirror 221. As a result, there is no gap between the light-receiving mirror 221 and the irradiating mirror 222 at the base of the V-shape. Therefore, it is possible to prevent laser light from the irradiating side from entering the light-receiving side through that gap.

[0061] Thus, according to the third embodiment of this technology, the end face of the illuminating mirror 222 is in contact with the back surface of the light-receiving mirror 221, thus eliminating the gap between the mirrors.

[0062] <4. Fourth Embodiment> In the first embodiment described above, the illuminating mirror 222 was shifted to the rear, but the configuration is not limited to this. The distance measuring device 100 in this fourth embodiment differs from the first embodiment in that the light-receiving mirror 221 is shifted to the rear.

[0063] Figure 13 is an example of a top view of a V-shaped oscillating mirror 220 in a fourth embodiment of this technology. In this fourth embodiment, if the distance from the light-receiving mirror 221 to the rotation axis 224 is d1 and the distance from the irradiating mirror 222 to the rotation axis 224 is d2, then d1 is smaller than d2. In other words, the light-receiving mirror 221 is positioned shifted inward relative to the irradiating mirror 222.

[0064] By shifting the light-receiving mirror 221 to the rear, the position of the light-emitting unit 120 on the Y-axis is also shifted to the rear by the same amount, preventing the laser light (stray light) reflected by the optical window 110 from entering the light-receiving side.

[0065] Furthermore, the end face of the light-receiving mirror 221 can be positioned in contact with the back surface of the illuminating mirror 222 to eliminate the gap between them.

[0066] As described above, according to the fourth embodiment of this technology, the distance from the light-receiving mirror 221 to the rotation axis 224 is made shorter than the distance from the irradiating mirror 222 to the rotation axis 224, so that the light-emitting unit 120 can be shifted inward by that amount. This prevents the laser light reflected by the optical window 110 from entering the light-receiving side, and improves the distance measurement performance, especially for objects at close range.

[0067] <5. Fifth Embodiment> In the first embodiment described above, the illuminating mirror 222 was shifted to the rear side. However, in this arrangement, a gap is created between one end of the light-receiving mirror 221 and one end of the illuminating mirror 222 at the base of the V-shape. The distance measuring device 100 in this fifth embodiment differs from the first embodiment in that a light-shielding component is placed between the light-receiving mirror 221 and the illuminating mirror 222 and the optical window 110.

[0068] Figure 14 is an example of a top view of a V-shaped oscillating mirror 220 in a fifth embodiment of the present technology. In this fifth embodiment, the distance from the light-receiving mirror 221 to the rotation axis 224 and the distance from the irradiating mirror 222 to the rotation axis 224 are both d.

[0069] Furthermore, a light-shielding component 226 is positioned between the light-receiving mirror 221 and the irradiating mirror 222 and the optical window 110. The light-shielding component 226 can be made of metal or resin, as long as it can block laser light such as infrared light. Because this light-shielding component 226 blocks the laser light from the light-emitting side, it is possible to prevent laser light (stray light) reflected by the optical window 110 from entering the light-receiving side.

[0070] As described above, according to the fifth embodiment of this technology, since a light-shielding component 226 is placed between the light-receiving mirror 221 and the irradiating mirror 222 and the optical window 110, it is possible to prevent laser light (stray light) reflected by the optical window 110 from entering the light-receiving side.

[0071] <6. Sixth Embodiment> In the first embodiment described above, the illuminating mirror 222 was shifted to the rear side. However, in this arrangement, a gap is created between one end of the light-receiving mirror 221 and one end of the illuminating mirror 222 at the base of the V-shape.

[0072] As illustrated in Figure 15a, when the V-shaped oscillating mirror 220 is rotated clockwise, there is a risk that laser light from the irradiating side may enter the receiving side through the gap.

[0073] Furthermore, a gap is created between the mirror holder 223 and the base 225, and as illustrated in figure b, when the V-shaped oscillating mirror 220 is rotated counterclockwise, there is a risk that laser light from the irradiating side may enter the receiving side through this gap.

[0074] The distance measuring device 100 in this sixth embodiment differs from the first embodiment in that gap-filling components are arranged to seal the gaps.

[0075] Figure 16 is an example of a top view of a V-shaped oscillating mirror 220 in a sixth embodiment of the present technology. The V-shaped oscillating mirror 220 in this sixth embodiment differs from the first embodiment in that it further includes gap components 227, 228, and 229. The gap components 227, 228, and 229 may be made of metal or resin, as long as they block laser light such as infrared light.

[0076] The gap component 227 is positioned to fill the gap between the light-receiving mirror 221 and the illuminating mirror 222. When the V-shaped oscillating mirror 220 rotates counterclockwise by R (e.g., 30 degrees), the reflection angle of the reflected light reflected by the illuminating mirror 222 is at most 2 × R (e.g., 60 degrees). Therefore, a portion of the gap component 227 is cut to prevent the reflected light reflected at that 2 × R reflection angle from being blocked. In the figure, a portion of the gap component 227 protrudes toward the illuminating side, and the angle between the inclined surface of the protruding portion and the normal perpendicular to the mirror surface of the illuminating mirror 222 is set to 2 × R or greater. Note that the gap component 227 is an example of the first gap component described in the claims.

[0077] Furthermore, the gap components 228 and 229 are positioned to fill the gap between the mirror holder 223 and the base 225. Note that the gap components 228 and 229 are examples of the second gap components described in the claims.

[0078] Furthermore, gap components 228 and 229 can also be provided in each of the second to fifth embodiments. Also, of the gap components 227 to 229, only gap component 227 can be provided, or only gap components 228 and 229 can be provided.

[0079] The gap component 227 prevents laser light from the irradiating side from entering the light-receiving side through the gap between one end of the light-receiving mirror 221 and one end of the irradiating mirror 222. Additionally, gap components 228 and 229 prevent laser light from the irradiating side from entering the light-receiving side through the gap between the mirror holder 223 and the base 225.

[0080] Note that the shape of the gap component 227 is not limited to the shape exemplified in the figure.

[0081] For example, as illustrated in Figure 17, the gap component 227 can be made trapezoidal, with its lower edge glued to the back surface of the light-receiving mirror 221 and its upper edge glued to the end face of the irradiating mirror 222.

[0082] Furthermore, as illustrated in Figure 18, the gap component 227 can also be a composite shape of a trapezoid and a rectangle. In this case, the bottom edge of the trapezoid and the short side of the rectangle are bonded to the back surface of the light-receiving mirror 221, and the top edge of the trapezoid and a part of the long side of the rectangle are bonded to the end face and back surface of the illuminating mirror 222.

[0083] Thus, according to the sixth embodiment of this technology, since the gap component 227 is placed between the light-receiving mirror 221 and the irradiation-side mirror 222, it is possible to prevent laser light from the irradiation side from entering the light-receiving side through the gap between the mirrors. Furthermore, since the gap components 228 and 229 are placed between the mirror holder 223 and the base 225, it is possible to prevent laser light from the irradiation side from entering the light-receiving side through the gap between the mirror holder 223 and the base 225.

[0084] [Modified Version] In the sixth embodiment described above, a gap component 227 was placed between the light-receiving mirror 221 and the illumination-side mirror 222, but it is also possible to mold one of the mirrors and the gap component as a single unit. The distance measuring device 100 in this modified version of the sixth embodiment differs from the sixth embodiment in that the light-receiving mirror 221 or the illumination-side mirror 222 and the gap component are integrated.

[0085] Figure 19 is an example of a top view of a V-shaped oscillating mirror 220 in a modified version of the sixth embodiment of this technology. In the modified version of the sixth embodiment, the light-receiving mirror 221 and the gap component are molded as a single unit. The black area in the figure indicates the integrated region. At one end of the light-receiving mirror 221, a portion protrudes from the back surface, and this protruding portion corresponds to the gap component. This protruding portion is bonded to the end surface and back surface of the illuminating mirror 222.

[0086] As illustrated in Figure 20, the illuminating mirror 222 and the gap component can also be molded as a single unit. The black area in the figure indicates the integrated region. At one end of the illuminating mirror 222, a portion protrudes from the end face, and this protruding portion corresponds to the gap component. This protruding portion is bonded to the back surface of the light-receiving mirror 221.

[0087] As illustrated in Figures 19 and 20, the light-receiving mirror 221 or the illuminating mirror 222 and the gap component are integrated, eliminating the need to manufacture the gap component separately from the mirror.

[0088] Thus, according to the modified sixth embodiment of this technology, the light-receiving mirror 221 or the irradiating mirror 222 and the gap component are integrated, thereby simplifying the manufacturing process.

[0089] The embodiments described above are merely examples of how to realize this technology, and there is a corresponding relationship between the matters in the embodiments and the inventive features in the claims. Similarly, there is a corresponding relationship between the inventive features in the claims and the matters in the embodiments of this technology that bear the same name. However, this technology is not limited to the embodiments and can be realized by making various modifications to the embodiments without departing from the gist of the technology.

[0090] The effects described herein are merely illustrative and not limited to those described herein, and other effects may also occur.

[0091] Furthermore, this technology can also be configured as follows: (1) A distance measuring device comprising: an irradiating mirror rotatable around a predetermined rotation axis; a light-emitting unit that irradiates the irradiating mirror with laser light; a light-receiving mirror rotatable together with the irradiating mirror around the rotation axis and having a distance from the irradiating mirror that is different from that of the irradiating mirror; a light-receiving unit that receives the laser light reflected by the light-receiving mirror; and a distance-measuring calculation unit that calculates the distance based on the signal from the light-receiving unit. (2) The distance measuring device according to (1), wherein the distance from the irradiating mirror to the rotation axis is shorter than the distance from the light-receiving mirror to the rotation axis. (3) The distance measuring device according to (2), wherein the end face of the irradiating mirror is in contact with one of the two surfaces of the light-receiving mirror. (4) The distance measuring device according to (2), further comprising a first gap component disposed between the irradiating mirror and the light-receiving mirror. (5) The distance measuring device according to (4), wherein the first gap component is bonded to the illuminating mirror and the light-receiving mirror. (6) The distance measuring device according to any one of (1) to (5), further comprising: a mirror holder that holds the illuminating mirror and the light-receiving mirror in a V-shape; a base that holds the mirror holder so as to be rotatable around the rotation axis; and a second gap component disposed between the mirror holder and the base. (7) The distance measuring device according to (1), wherein the light-receiving mirror has a protrusion, and the protrusion is bonded to the back surface of the illuminating mirror. (8) The distance measuring device according to (1), wherein the illuminating mirror has a protrusion, and the protrusion is bonded to the back surface of the light-receiving mirror. (9) The distance measuring device according to (1), wherein the distance from the illuminating mirror to the rotation axis is longer than the distance from the light-receiving mirror to the rotation axis. (10) A distance measuring device comprising: an irradiating mirror rotatable around a predetermined axis of rotation; a light-emitting unit that irradiates the irradiating mirror with laser light; a light-receiving mirror rotatable together with the irradiating mirror around the axis of rotation and having a size in the direction parallel to the mirror surface that is smaller than that of the irradiating mirror; a light-receiving unit that receives the laser light reflected by the light-receiving mirror; and a distance-measuring calculation unit that calculates the distance based on the signal from the light-receiving unit.(11) A distance measuring device comprising: an optical window; a pair of mirrors rotatable around a predetermined axis of rotation; a light-emitting unit that irradiates laser light onto one of the pair of mirrors; a light-receiving unit that receives the laser light reflected by the other of the pair of mirrors; a distance-measuring calculation unit that calculates the distance based on the signal from the light-receiving unit; and a light-shielding component disposed between the optical window and the pair of mirrors.

[0092] 100 Distance measuring device 110 Optical window 120 Light-emitting unit 121 Projection lens 122 Semiconductor laser light source 130 Light-receiving unit 131 Light-receiving lens 132 Line sensor 140 Control unit 150 Distance calculation unit 160 External interface 200 Scanning unit 210 Folding mirror 220 V-shaped oscillating mirror 221 Light-receiving mirror 222 Irradiating mirror 223 Mirror holder 224 Rotation axis 225 Base 226 Light-shielding parts 227, 228, 229 Gap parts 300 Object to be measured 400 Host

Claims

1. A distance measuring device comprising: an irradiating mirror rotatable around a predetermined axis of rotation; a light-emitting unit that irradiates the irradiating mirror with laser light; a light-receiving mirror rotatable together with the irradiating mirror around the axis of rotation and having a distance from the axis of rotation that is different from that of the irradiating mirror; a light-receiving unit that receives the laser light reflected by the light-receiving mirror; and a distance-measuring calculation unit that calculates the distance based on the signal from the light-receiving unit.

2. The distance measuring device according to claim 1, wherein the distance from the illuminating mirror to the rotation axis is shorter than the distance from the light-receiving mirror to the rotation axis.

3. The distance measuring device according to claim 2, wherein the end face of the illuminating mirror is in contact with one of the two surfaces of the light-receiving mirror.

4. The distance measuring device according to claim 2, further comprising a first gap component disposed between the illuminating mirror and the light-receiving mirror.

5. The distance measuring device according to claim 4, wherein the first gap component is bonded to the irradiating mirror and the light-receiving mirror.

6. The distance measuring device according to claim 1, further comprising: a mirror holder that holds the illuminating mirror and the light-receiving mirror in a V-shape; a base that rotatably holds the mirror holder around the rotation axis; and a second gap component disposed between the mirror holder and the base.

7. The distance measuring device according to claim 1, wherein the light-receiving mirror is provided with a protrusion, and the protrusion is bonded to the back surface of the irradiating mirror.

8. The distance measuring device according to claim 1, wherein the irradiating mirror is provided with a protrusion, and the protrusion is bonded to the back surface of the light-receiving mirror.

9. The distance measuring device according to claim 1, wherein the distance from the illuminating mirror to the rotation axis is longer than the distance from the light-receiving mirror to the rotation axis.

10. A distance measuring device comprising: an irradiating mirror rotatable around a predetermined axis of rotation; a light-emitting unit that irradiates the irradiating mirror with laser light; a light-receiving mirror rotatable together with the irradiating mirror around the axis of rotation and having a size in the direction parallel to the mirror surface that is smaller than that of the irradiating mirror; a light-receiving unit that receives the laser light reflected by the light-receiving mirror; and a distance-measuring calculation unit that calculates the distance based on the signal from the light-receiving unit.

11. A distance measuring device comprising: an optical window; a pair of mirrors rotatable around a predetermined axis of rotation; a light-emitting unit that irradiates laser light onto one of the pair of mirrors; a light-receiving unit that receives the laser light reflected by the other of the pair of mirrors; a distance-measuring calculation unit that calculates the distance based on the signal from the light-receiving unit; and a light-shielding component disposed between the optical window and the pair of mirrors.

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