Light detection and ranging

Abstract

To provide a LiDAR (Light Detection and Ranging) that can prevent damage of a mirror.SOLUTION: A mirror 18 of a LiDAR (Light Detection and Ranging) 1 is oscillated and driven by an oscillation motor 20, and scans light towards the outside. A base 11 has the mirror 18 provided inside. A spindle 13, in which the mirror 18 is fixed, is rotatably supported on the base 11 in a state where at least one end part protrudes from the base 11. A position holding part 16 has a preload spring 165 that urges the spindle 13 toward one side in an axial direction, and an E ring 161 that restricts a movement to an urging direction of the spindle 13, and supports a position in the axial direction of the spindle 13. A disk hub 31 is fixed to the spindle 13 at an outer side of the base 11. A distance between an end part of the disk hub 31 present in a direction opposite the urging direction of the spindle 13 and a housing part 50 is smaller than that between an end part of the mirror 18 in a direction opposite the urging direction of the spindle 13 and the base 11.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a distance measuring device. [Background technology]

[0002] Conventionally, there is known a rotary reciprocating actuator used for LiDAR (Light Detection and Ranging). For example, in Patent Document 1, a rotary shaft to which a mirror part is attached is rotatably attached to a left side wall part and a right side wall part of a base via bearings. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-127381 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a structure in which a mirror is placed between opposing wall surfaces as in Patent Document 1, when the axial position is regulated by, for example, a preload spring, there is a risk that the mirror will come into contact with the wall surface and be damaged if it receives an impact that exceeds the load generated by the preload spring.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a distance measuring device capable of preventing damage to the mirror. [Means for solving the problem]

[0006] The distance measuring device of the present invention measures the distance to an object by scanning light externally and detecting the light reflected by the object, and is equipped with a mirror (18), a base (11), an oscillating shaft (13, 130), a position holding part (16), and an abutment member (31).

[0007] The mirror is driven to swing by an actuator (20) to scan the light to the outside. The base has the mirror disposed therein. The swing shaft has the mirror fixed thereto and is swingably supported by the base with at least one end protruding from the base. The position retaining portion has a biasing member (165) that biases the swing shaft to one side in the axial direction, and a position restricting portion (161, 132) that restricts movement of the swing shaft in the biasing direction, and retains the axial position of the swing shaft. The abutment member is fixed to the swing shaft on the outside of the base.

[0008] The portion that includes the base and is not driven by the actuator is referred to as the housing portion (50). The distance between the end of the contact member on the side opposite to the biasing direction of the oscillation shaft and the housing portion is smaller than the distance between the end of the mirror on the side opposite to the biasing direction of the oscillation shaft and the base. This makes it possible to prevent damage to the mirror. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a distance measuring device according to a first embodiment. [Diagram 2] 1 is a cross-sectional view showing a rocking actuator according to a first embodiment. [Diagram 3] FIG. 11 is a cross-sectional view showing a rocking actuator according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A distance measuring device according to the present invention will now be described with reference to the drawings. In the following, in a number of embodiments, substantially the same components are designated by the same reference numerals, and description thereof will be omitted.

[0011] (First embodiment) The first embodiment is shown in Figures 1 and 2. As shown in Figure 1, the distance measuring device 1 is a LiDAR (Light Detection and Ranging) device that measures the distance to an object by irradiating light and detecting reflected light from the object on which the light is irradiated. The distance measuring device 1 is mounted on, for example, a vehicle and used to detect an object present in front of the vehicle.

[0012] The distance measuring device 1 includes a light emitting unit 91, a light receiving unit 92, and a swing actuator 5, and is housed in a housing 93. The light emitting unit 91 intermittently outputs a light beam B. The output light beam B is reflected by a mirror 18 that is driven to swing, and is emitted to the outside through an optical window 94. The light receiving unit 92 receives the reflected light from an object irradiated with the light beam B. The light detected by the light receiving unit 92 is converted into an electrical signal, and is used to calculate the distance to the object.

[0013] As shown in Fig. 2, the oscillation actuator 5 includes a mirror section 10, an oscillation motor 20, and an encoder 30. The mirror section 10 includes a base 11, a spindle 13, a position holder 16, a holder 17, and a mirror 18. The base 11 includes an attachment section 111 and holding walls 112 and 113, which are integrally formed from, for example, metal. The attachment section 111 is attached to a base housing (not shown) by bolts or the like. The holding walls 112 and 113 are provided substantially vertically on both ends of the attachment section 111.

[0014] The spindle 13 is disposed approximately parallel to the mounting portion 111, and is rotatably supported on the base 11 by bearings 14, 15 provided on the retaining walls 112, 113. The bearings 14, 15 in this embodiment are ball bearings, but bearings other than ball bearings may be used. The spindle 13 is formed extending from the bearing side 15 to the outside of the base 11 toward the oscillating motor 20 and encoder 30. Hereinafter, the oscillating axis direction of the spindle 13 will be simply referred to as the "axial direction" as appropriate.

[0015] The position retaining portion 16 has an E-ring 161 and a preload spring 165, and positions the axial position of the spindle 13 while being pressed to one side in the axial direction. The E-ring 161 is provided on the axial outer side of the bearing 14, and functions to prevent the spindle 13 from coming off.

[0016] The preload spring 165 is provided between the rotor magnet 22 and the bearing 15, with one end abutting against the inner ring of the bearing 15 and the other end abutting against the rotor magnet 22. Another member may be provided between the rotor magnet 22 and the preload spring 165. The preload spring 165 biases the spindle 13 towards the encoder 30 (towards the left in the plane of the paper in FIG. 2). That is, in this embodiment, a member for retaining the axial position of the spindle 13 is not provided inside the base 11, and therefore optical consideration for the position retaining unit 16 is not required.

[0017] The holder 17 is press-fitted and fixed to the spindle 13. The mirror 18 is formed in a flat plate shape and is attached to the holder 17 so as to be symmetrical about the oscillation axis. By forming the holder 17 and the mirror 18 symmetrical about the oscillation axis, the moment of inertia during oscillation can be made equal in both directions.

[0018] The holder 17 and the mirror 18 are disposed inside the base 11 so that the mirror surface 181 faces away from the mounting portion 111, and are driven to swing by the swing motor 20. The mirror 18 reflects the light beam B output from the light emitting portion 91 on the mirror surface 181, and emits the light beam B to the outside in a direction according to the swing position of the mirror 18, thereby scanning the light beam B within a preset scanning range.

[0019] The oscillation motor 20 is provided on one side in the axial direction of the mirror unit 10. The oscillation motor 20 has a stator 21, a rotor magnet 22, etc. The stator 21 is fixed to the holding wall 113 with bolts or the like. The stator 21 is provided with an electromagnetic coil and a fixed magnet (not shown). The rotor magnet 22 is a cylindrical two-pole magnet, and the spindle 13 is inserted into the shaft hole 221 and fixed to the spindle 13 by a magnet fixing member 23.

[0020] The rotor magnet 22 is a so-called inner rotor that is disposed inside the stator 21, and oscillates around a stationary position when current is applied to the electromagnetic coil. Here, the oscillating motion is a motion that periodically repeats forward and reverse rotations within a predetermined angular range less than 360°. When current is turned off to the electromagnetic coil, the rotor magnet 22 returns to the stationary position and becomes stationary due to the magnetic force of the fixed magnet. The size of the rotor magnet 22 can be designed arbitrarily according to mounting constraints, the required magnetic force, and the like.

[0021] The encoder 30 is, for example, a reflective optical encoder, and has a disk hub 31, a disk 32, and a detection element 33, and is housed in a case 35. The disk hub 31 is press-fitted and fixed to the spindle 13. The disk 32 is attached to the disk hub 31, and rotates integrally with the spindle 13. Reflective and non-reflective patterns are formed on the disk 32 in the circumferential direction.

[0022] The detection element 33 is mounted on a substrate 34. The detection element 33 is an optical sensor that emits LED light, receives light reflected in accordance with the rotation of the disk 32, and detects the rotational position of the disk 32 based on a change in the amount of light received. This allows the encoder 30 to detect the oscillation positions of the oscillation motor 20 and the mirror 18. The substrate 34 is fixed to the case 35 by screws or the like (not shown). A through hole 341 is formed in the substrate 34, and the spindle 13 is inserted therethrough.

[0023] The case 35 is formed in a cylindrical shape with a bottom that opens on the side opposite the mirror unit 10, and is fixed to the stator 21 by, for example, a through bolt (not shown). An insertion hole 352 is formed in the bottom 351, and the spindle 13 is inserted through the insertion hole 352. The bottom 351 is located between the rotor magnet 22 and the disk hub 31. In this embodiment, the base 11, the stator 21, and the case 35, which do not move even when the oscillating motor 20 is driven, are the housing unit 50.

[0024] In this embodiment, the axial position of the spindle 13 is restricted by the E-ring 161 and the preload spring 165, and the spindle 13 is biased in the opposite direction to the E-ring 161 (i.e., the leftward direction on the paper surface) by the preload spring 165. If vibration or impact is applied to the swing actuator 5 and the spindle 13 moves in the axial direction, the mirror 18 may come into contact with the base 11, which may damage the mirror 18.

[0025] When an impact is applied to the swing actuator 5, the movement of the spindle 13 to the left on the page is restricted by the E-ring 161. On the other hand, when an impact exceeding the load of the preload spring 165 is received, there is a risk that the spindle 13 will move to the right on the page. In order to be able to withstand a larger impact, it is possible to increase the spring force of the preload spring 165, but in that case, the size of the spindle 13 will increase. Hereinafter, the direction in which the spindle 13 moves when an impact exceeding the spring force of the preload spring 165 is received (i.e., the rightward direction on the page) is referred to as the "axial movement direction".

[0026] In this embodiment, there is provided a portion where the clearance between the member fixed to the spindle 13 and the housing part 50 is smaller than the clearance C1 between the mirror 18 and the retaining wall 112 of the base 11 in the axial movement direction. Specifically, the clearance C2 between the disk hub 31 and the bottom part 351 of the case 35 is smaller than the clearance C1 between the mirror 18 and the retaining wall 112.

[0027] As a result, when an impact greater than the load of the preload spring 165 is applied to the oscillating actuator 5 and the spindle 13 moves in the axial movement direction, the disk hub 31 abuts against the case 35 before the mirror 18 abuts against the base 11, so that the mirror 18 does not collide with the base 11 and damage to the mirror 18 can be prevented.

[0028] Furthermore, if the disk hub 31 comes into contact with the case 35 due to movement of the spindle 13 caused by vibration, impact, etc., and the disk hub 31 is deformed or damaged, the positional relationship between the disk 32 and the detection element 33 becomes abnormal, causing a sensing abnormality. This makes it possible to detect an abnormality occurring in the oscillating actuator 5.

[0029] As described above, the distance measuring device 1 of this embodiment measures the distance to an object by scanning light externally and detecting the light reflected by the object, and comprises a mirror 18, a base 11, a spindle 13, a position holding unit 16, and a disk hub 31.

[0030] The mirror 18 is driven to swing by a swing motor 20, thereby scanning the light to the outside. The mirror 18 is provided inside the base 11. The spindle 13 has the mirror 18 fixed thereto, and is rotatably supported by the base 11 with at least one end thereof protruding from the base 11. The position holder 16 has a preload spring 165 that biases the spindle 13 to one side in the axial direction, and an E-ring 161 that restricts movement of the spindle 13 in the biasing direction, and holds the axial position of the spindle 13. The disk hub 31 is fixed to the spindle 13 on the outside of the base 11.

[0031] A fixed portion including the base 11 and not driven by the oscillating motor 20 is defined as a housing portion 50. The distance between the housing portion 50 and the end of the disk hub 31 on the side opposite to the biasing direction of the spindle 13 is smaller than the distance between the base 11 and the end of the mirror 18 on the side opposite to the biasing direction of the spindle 13. Specifically, a clearance C2 between the disk hub 31 and the bottom 351 of the case 35 is smaller than a clearance C1 between the mirror 18 and the retaining wall 112.

[0032] As a result, when an impact greater than the load of the preload spring 165 is applied to the oscillation actuator 5, the disk hub 31 abuts against the case 35, preventing the mirror 18 from colliding with the base 11. Therefore, damage to the mirror 18 can be prevented. Furthermore, when providing a structure inside the base 11 that abuts against the base 11 before the mirror 18, optical considerations such as avoiding high reflection are required. In this embodiment, the disk hub 31, which is the abutting member, is provided on the outside of the base 11, so optical considerations and restrictions for providing the abutting structure can be reduced.

[0033] In the distance measuring device 1, an oscillating motor 20 and an encoder 30 capable of detecting the oscillating position of the mirror 18 are provided on the outside of the base 11. The encoder 30 has a disk 32 that is driven integrally with the spindle 13, a disk hub 31 that is fixed to the spindle 13 and to which the disk 32 is attached, and a detection element 33 that detects the driving state of the disk 32. In detail, the detection unit is an encoder, and the detection element 33 is an optical sensor that detects light reflected by the disk 32.

[0034] In this embodiment, the contact member is the disk hub 31. By configuring the disk hub 31 to contact the case 35 when an impact is applied to the oscillating actuator 5, an abnormality in the oscillating actuator 5 can be detected.

[0035] The position retaining portion 16 is provided outside the base 11. In other words, a member related to retaining the axial position of the spindle 13 is not provided inside the base 11. The position restricting portion is an E-ring 161 provided on the opposite side of the base 11 to the preload spring 165. This allows the axial positioning of the spindle 13 to be determined without affecting the light scanning by the mirror 18.

[0036] Second embodiment The second embodiment is shown in FIG. 3. In this embodiment, the shape of the spindle 130 is different from that of the above embodiment, and this point will be mainly described. In the spindle 130 of this embodiment, the shaft portion 131 and the position restriction portion 132 are integrally formed. The position restriction portion 132 is provided on the axial outside of the bearing 14, protruding radially outward from the shaft portion 131, and functions as a retainer for the spindle 130. That is, in this embodiment, the preload spring 165 and the position restriction portion 132 constitute the position retaining portion 16. Even with this configuration, the same effects as the above embodiment can be achieved.

[0037] In the embodiment, the spindles 13, 130 correspond to the "oscillating axis", the E-ring 161 and the position regulating portion 132 correspond to the "position regulating portion", the preload spring 165 corresponds to the "biasing member", the encoder 30 corresponds to the "detection portion", the disk hub 31 corresponds to the "contact member" and the "holding member", and the disk 32 corresponds to the "detected portion".

[0038] (Other embodiments) In the above embodiment, the clearance C2 between the disk hub 31 and the bottom 351 of the case 35 is smaller than the clearance C1 between the mirror 18 and the retaining wall 112. In other embodiments, the abutting member may be a member other than the disk hub. That is, a portion may be provided where the clearance between the end of the member other than the disk hub on the axial movement direction side and the housing is smaller than the clearance C1. Note that if the abutting member is provided inside the base, optical consideration is required so as not to interfere with reflection on the mirror, so it is preferable to provide the abutting member on the outside of the base.

[0039] In the above embodiment, the detection element is an optical sensor. In other embodiments, something other than an optical sensor (e.g., a magnetic sensor) may be used to detect the driving state of the oscillating shaft, and something other than an encoder may be used as the detection unit. Also, in other embodiments, the actuator and mirror unit may have a configuration, arrangement, etc. different from those of the above embodiment, as long as they can oscillate the mirror. As described above, the present invention is not limited to the above embodiment, and can be embodied in various forms without departing from the spirit of the invention. [Explanation of symbols]

[0040] 1... Distance measuring device 5... Swing actuator 11. Base 13, 130... Spindle (oscillating shaft) 132... Position control part 16...Position holding part 161 E-ring (position control portion) 165 Preload spring (biasing member) 18. Mirror 20.... Swing motor (actuator) 30 Encoder (detection unit) 31...Disc hub (contact member, holding member) 32 Disk (detection target) 50 Housing

Claims

1. A distance measuring device that measures a distance to an object by scanning light externally and detecting light reflected by the object, A mirror (18) that scans light to the outside by being driven to swing by an actuator (20); A base (11) in which the mirror is mounted; a swing shaft (13, 130) to which the mirror is fixed and which is swingably supported by the base with at least one end protruding from the base; a position retaining section (16) having a biasing member (165) for biasing the rocking shaft toward one side in the axial direction and a position restricting section (161, 132) for restricting movement of the rocking shaft toward the biasing direction side, and retaining the axial position of the rocking shaft; a contact member (31) fixed to the pivot shaft on the outside of the base; Equipped with If a fixed portion including the base and not driven by the actuator is defined as a housing portion (50), A distance measuring device, wherein the distance between the end of the abutment member on the side opposite to the biasing direction of the oscillating shaft and the housing portion is smaller than the distance between the end of the mirror on the side opposite to the biasing direction of the oscillating shaft and the base.

2. A detector (30) capable of detecting the actuator and the swing position of the mirror is provided on the outside of the base, The detection unit includes a detected part (32) that is driven integrally with the pivot shaft, a holding member (31) that is fixed to the pivot shaft and to which the detected part is attached, and a detection element (33) that detects the drive state of the detected part, 2. The distance measuring device according to claim 1, wherein the contact member is the holding member.

3. The detection unit is an encoder, 3. The distance measuring device according to claim 2, wherein the detection element is an optical sensor that detects light reflected by the detection target portion.

4. The position maintaining portion is provided on the outside of the base, 4. The distance measuring device according to claim 1, wherein the position restriction portion is an E-ring provided on the opposite side of the base from the biasing member.

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