Optical scale, ranging device, and method of manufacturing optical scale

Abstract

To provide an optical scale that offers high machining precision without increasing manufacturing costs, and to provide a ranging device and a method of manufacturing the optical scale.SOLUTION: An optical scale is provided, comprising a slit surface having one or more pairs of slits, each consisting of a first slit and a second slit configured to be different in terms of at least one of reflectance and reflecting direction, and an optical member integrally bonded to the slit surface to provide predetermined optical control.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an optical scale, a distance measuring device, and a method for manufacturing an optical scale.

Background Art

[0002] In a LiDAR (Light Detection And Ranging) device used in autonomous driving technology and the like, it is common to use a polygon mirror to scan the laser light from a light emitting unit within a predetermined angular range. An optical scale is rotatably attached to the rotation axis of the polygon mirror, and light from an encoder IC is irradiated onto a plurality of slits provided on the optical scale, and the reflected light is received by the encoder IC to detect the scanning angle of the polygon mirror.

[0003] The work of accurately attaching the polygon mirror and the optical scale to the rotation axis and the work of accurately forming a plurality of slits on the optical scale at uniform intervals and sizes are factors that increase the manufacturing cost and man-hours. It is necessary to alternately form low-reflection slits and high-reflection slits on the optical scale. However, since some light is reflected from the low-reflection slits, there is a risk of misjudging which of the low-reflection slits and the high-reflection slits the light is reflected from.

[0004] In addition, optical slits are generally manufactured by die cutting using a mold. However, in order to accurately detect the scanning angle, it is necessary to form a large number of slits on the optical slits at uniform intervals and sizes, which requires a high processing accuracy of the mold and leads to an increase in manufacturing cost.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, the present disclosure provides an optical scale, a distance measuring device, and a method for manufacturing an optical scale with high machining accuracy without increasing the manufacturing cost.

Means for Solving the Problems

[0007] In order to solve the above problems, according to the present disclosure, a slit surface on which one or more slit pairs having a first slit and a second slit, at least one of the reflectance or the reflection direction of which is different from each other, are arranged, and an optical member integrally joined to the slit surface and performing predetermined optical control are provided. An optical scale is provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11A

Figure 11B

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of an optical scale, a distance measuring device, and a method for manufacturing an optical scale will be described with reference to the drawings. Hereinafter, the main components of the optical scale and the distance measuring device will be mainly described, but the optical scale and the distance measuring device may have components and functions not shown or described. The following description does not exclude components and functions not shown or described.

[0010] FIG. 1 is a schematic perspective view of an optical scanning device 2 including an optical scale 1 according to an embodiment. The optical scanning device 2 in FIG. 1 is used in a distance measuring device such as LiDAR.

[0011] The optical scanning device 2 in FIG. 1 scans the light (for example, laser light) emitted by the light projecting unit 21 within a predetermined angular range. The optical scanning device 2 in FIG. 1 includes an optical scale 1 integrally formed with a polygon mirror 3, a motor 4, and an encoder IC 5.

[0012] The optical scale 1 is rotatably attached to the rotating shaft 6 of the motor 4. When the motor 4 rotates the rotating shaft 6, the optical scale 1 integrally formed with the polygon mirror 3 rotates in synchronization with the rotation direction and rotation speed of the rotating shaft 6.

[0013] The polygon mirror 3 is integrally formed on the slit surface 1a of the optical scale 1. The polygon mirror 3 has two or more mirror surfaces 3a. Each mirror surface 3a is connected to the slit surface 1a and is arranged in a different direction. Each mirror surface 3a extends along the axial direction of the rotating shaft 6 and rotates in synchronization with the rotation of the rotating shaft 6. By increasing the number of mirror surfaces 3a of the polygon mirror 3, the scanning direction of the light from the light emitting device can be switched in fine units, and the resolution of the distance image generated by the LiDAR can be improved.

[0014] Note that this embodiment is also applicable to an optical scale 1 in which an arbitrary optical member such as a galvanometer mirror is integrally formed instead of the polygon mirror 3. An optical member is a member that performs predetermined optical control. Predetermined optical control includes reflection, scattering, refraction, or absorption of incident light. Hereinafter, the optical scale 1 integrally formed with the polygon mirror 3 as the optical member will be mainly described.

[0015] The optical scale 1 has a slit surface 1a on which a plurality of slit pairs are arranged. The slit surface 1a is irradiated with light from the encoder IC 5. The encoder IC 5 has a light-emitting element 5a, a light-receiving element 5b, and a rotation angle detection unit 5c. The installation location of the encoder IC 5 is fixed, and the light-emitting element 5a periodically irradiates light in a fixed direction. The optical scale 1 is arranged at a location where light from the light-emitting element 5a of the encoder IC 5 is incident and rotates around the rotation axis 6. When the light from the light-emitting element 5a is irradiated onto a high-reflection slit (to be described later) of the optical scale 1, the high-reflection slit always reflects the light from the light-emitting element 5a in the same direction. The light-receiving element 5b of the encoder IC 5 is arranged in the propagation direction of the reflected light of the high-reflection slit. Thereby, the light-receiving element 5b receives the reflected light from the high-reflection slit that has reflected the light from the light-emitting element 5a. The rotation angle detection unit 5c detects the rotation angle of the optical scale 1 based on the number of times the light is received by the light-receiving element 5b.

[0016] In FIG. 1, the polygon mirror 3 is arranged under the motor 4, the slit surface 1a is arranged under that, and the encoder IC 5 is further arranged under that. However, the arrangement locations of the motor 4, the polygon mirror 3, the slit surface 1a, and the encoder IC 5 are arbitrary. For example, the arrangement order of the polygon mirror 3 and the slit surface 1a may be reversed from that in FIG. 1.

[0017] The optical scale 1 according to the present embodiment is manufactured using a mold for integrally injection-molding the slit surface 1a and the polygon mirror 3. FIG. 2 is a perspective view of the mold 11 used for manufacturing the optical scale 1 according to the present embodiment. The mold 11 is formed by cutting a metal material such as steel. The mold 11 includes a recess 11b having an inner wall surface 11a shaped along the outer shape of the integrated slit surface 1a and polygon mirror 3. FIG. 2 shows an example of the mold 11 for manufacturing the pentahedral optical scale 1, but the number of mirror surfaces 3a of the optical scale 1 is an arbitrary number of two or more.

[0018] The side surface 11d of the mold 11 excluding the bottom surface 11c of the recess 11b is a flat surface. The side surface 11d serves as a mold for forming the mirror surface 3a of the polygon mirror 3. On the bottom surface 11c of the recess 11b, an uneven mold for forming a plurality of slit pairs in the circumferential direction is formed. By filling the heated thermosetting resin material into the recess 11b and curing it, and then taking out the cured resin from the mold 11 and mirror-finishing at least a part of the surface of the resin, for example, by plating, the optical scale 1 is produced.

[0019] FIG. 3 is an enlarged perspective view of a part of the slit surface 1a of the optical scale 1. As shown in FIG. 3, on the slit surface 1a of the optical scale 1, one or more slit pairs 14 having a first slit 12 and a second slit 13, at least one of the reflectance or the reflection direction of which is different from each other, are arranged. Typically, a plurality of slit pairs 14 are arranged in the circumferential direction on the slit surface 1a. The first slit 12 of each slit pair 14 reflects the incident light in a direction corresponding to the incident direction, and the second slit 13 retroreflects the incident light.

[0020] In the example of FIG. 3, the first slit 12 and the second slit 13 extend radially from the rotation axis 6 located at the center of the optical slit. A plurality of slit pairs 14 are arranged in the circumferential direction of the rotation axis 6 on the slit surface 1a. Thus, on the slit surface 1a, a plurality of the first slits 12 and the second slits 13 are alternately arranged one by one in the circumferential direction centered on the rotation axis 6. The number of the slit pairs 14 is arbitrary, and the more the number of the slit pairs 14 increases, the more accurately the rotation angle of the polygon mirror 3 can be detected.

[0021] As shown in FIG. 3, the first slit 12 is a flat surface, while the second slit 13 has an uneven portion 15. The flat surface constituting the first slit 12 is, for example, mirror-finished and specularly reflects the incident light at an angle corresponding to the incident direction.

[0022] FIG. 4 is a diagram for explaining the characteristics of the second slit 13. The second slit 13 is a retroreflective member that reflects incident light in the incident direction. When the light emitted from the light-emitting element 5a of the encoder IC 5 is incident on the second slit 13, the second slit 13 reflects the light in the incident direction. As a result, among the light emitted from the light-emitting element 5a, the light incident on the second slit 13 is not received by the light-receiving element 5b of the encoder IC 5.

[0023] The second slit 13 has a plurality of uneven portions 15 arranged along the radial direction. FIG. 5A is a cross-sectional view showing the cross-sectional structure of the second slit 13. FIG. 5B is a perspective view showing the structure of one of the plurality of uneven portions 15 included in the second slit 13.

[0024] As shown in FIG. 5B, each of the plurality of uneven portions 15 has three surfaces arranged in directions intersecting each other. Typically, each of the plurality of uneven portions 15 has a corner cube structure having three flat surfaces arranged at different angles of 90 degrees from each other. In this specification, these three flat surfaces may be referred to as a first surface 16d, a second surface 16e, and a third surface 16f. The light incident on any one of the three surfaces is sequentially reflected by the other two surfaces and returns in the direction of the original incident light. FIGS. 5A and 5B illustrate the propagation directions of two light rays L1 and L2 in which the incident light is incident on different surfaces. As shown in FIG. 5B, regardless of which surface the light is incident on, retroreflection is performed in which the light is reflected twice and propagates in the direction of the original incident light.

[0025] As shown in FIGS. 5A and 5B, regardless of the incident angle at which the incident light is incident on the three surfaces of the second slit 13, the incident light is reflected in the direction of the original incident light.

[0026] FIG. 6 is a cross-sectional view of an optical scale 100 according to a comparative example. The optical scale 100 according to a comparative example has a scale surface 103 on which a first reflection scale 101 and a second reflection scale 102 are alternately arranged. The first reflection scale 101 has a flat surface and reflects incident light in a direction corresponding to the incident direction of the incident light. The second reflection scale 102 has an uneven surface 102a and scatters incident light. The first reflection scale 101 and the second reflection scale 102 are formed, for example, by coating the surface of a resin layer or a semiconductor layer 105 with a metal layer 106.

[0027] When the light emitted from the light-emitting element 5a of the encoder IC5 is incident on any one of the first reflection scales 101, the reflected light is received by the light-receiving element 5b. On the other hand, when the light emitted from the light-emitting element 5a of the encoder IC5 is incident on the second reflection scale 102, it is scattered, so the proportion of the light received by the light-receiving element 5b is less than that of the reflected light of the first reflection scale 101.

[0028] Therefore, ideally, the encoder IC5 can distinguish the light reflected by the first reflection scale 101 from the light reflected by the second reflection scale 102, and can detect the rotation angle of the optical scale 1 based on the light reflected by the first reflection scale 101.

[0029] However, in the optical scale 100 according to a comparative example, since a part of the light scattered by the second reflection scale 102 is received by the light-receiving element 5b, there is a possibility that the light reflected by the first reflection scale 101 and the light scattered by the second reflection scale 102 cannot be clearly distinguished, and an error may occur in angle detection.

[0030] On the other hand, in the optical scale 1 according to the present embodiment, since the second slit 13 that performs retroreflection is provided, the incident light of the second slit 13 is not received by the light-receiving element 5b, and only the reflected light from the first slit 12 is received by the light-receiving element 5b. Therefore, angle detection can be performed with higher accuracy than in the comparative example.

[0031] FIG. 7 is a diagram for explaining a method of manufacturing an optical scale 100 according to a comparative example. In the optical scale 100 according to a comparative example, a first reflection scale 101 and a second reflection scale 102 are alternately arranged in the circumferential direction, and the second reflection scale 102 has a plurality of unevennesses arranged in the radial direction. The optical scale 100 according to a comparative example can be manufactured using a mold 107. Concavities and convexities having a shape matching the outer shape of the optical scale 100 are formed on the bottom surface 107a of the concave portion of the mold 107, and the bottom surface 107a of the concave portion is processed to match the shapes of the first reflection scale 101 and the second reflection scale 102 alternately arranged in the circumferential direction.

[0032] FIG. 7 shows a state of processing the bottom surface 107a of the concave portion of the mold 107. It is necessary to form a concavity and convexity mold frame 108 having a shape matching the shape of a plurality of uneven surfaces 102a of the second reflection scale 102 on the bottom surface 107a of the concave portion of the mold 107. As shown in FIG. 7, the bottom surface 107a of the concave portion 11b is processed using a disk-shaped cutting edge 109. By rotating the cutting edge 109 in the direction of the arrow shown in the figure, the concavity and convexity mold frames 108 to be cut are formed one by one. The interval between the mold frames of two adjacent second reflection scales 102 in the circumferential direction is narrow on the center side and widens as it approaches the outer periphery. When performing processing on the center side using the cutting edge 109, as shown in FIG. 7, the cutting edge 109 may contact and damage the mold frame 108 of the adjacent second reflection scale 102. Thus, when processing the bottom surface 107a of the concave portion of the mold 107 using the disk-shaped cutting edge 109, the mold frame 108 of the second reflection scale 102 is likely to be damaged by the cutting edge 109, and a scratch caused by the cutting edge 109 also remains on the second reflection scale 102 of the optical scale 1 after die cutting. This scratch causes problems such as scattering the light from the light emitting element 5a of the encoder IC5, making it impossible to accurately detect the rotation angle of the polygon mirror 3.

[0033] FIG. 8 is a diagram for explaining a method of manufacturing the optical scale 1 according to the present embodiment. As shown in FIG. 2, the optical scale 1 according to the present embodiment is manufactured using a mold 11 for integrally molding the slit surface 1a and the polygon mirror 3. On the bottom surface 11c of the concave portion 11b of the mold 11, a mold frame 16 of a plurality of slit pairs 14 arranged in the circumferential direction is formed. The mold frame 16 of each slit pair 14 has a mold frame 16a of the first slit 12 and a mold frame 16b of the second slit 13. The mold frame 16b of the second slit 13 has a plurality of concavo-convex mold frames 16c arranged along the radial direction. Each concavo-convex mold frame 16c is for forming each concavo-convex portion 15 of the second slit 13. Therefore, on the bottom surface 11c of the concave portion 11b of the mold 11, it is necessary to form the same number of concavo-convex mold frames 16c as the plurality of concavo-convex portions 15 for each of the plurality of second slits 13.

[0034] In the present embodiment, a disk-shaped cutting blade is used to form the mold frames 16 of the plurality of slit pairs 14 arranged in the circumferential direction on the bottom surface 11c of the concave portion 11b of the mold 11. The mold frame 16b of the second slit 13 included in the mold frame 16 of each slit pair 14 has a plurality of concavo-convex mold frames 16c arranged in the radial direction. At this time, as shown in FIG. 7, while machining an arbitrary concavo-convex mold frame 16c in the mold frame 16b of the second slit 13 to be cut with the cutting blade, the cutting blade may come into contact with the mold frame 16b of another second slit 13 adjacent in the circumferential direction, damaging the mold frame 16b of this second slit 13. Therefore, in the present embodiment, while machining an arbitrary concavo-convex mold frame 16c in the mold frame 16b of the second slit 13 to be cut with the cutting blade, the cutting blade is brought into contact with the corresponding concavo-convex mold frames 16c in the mold frames 16b of two or more second slits 13 adjacent in the circumferential direction. Thereby, the risk of damaging the mold frame 16b of the second slit 13 with the cutting blade is eliminated.

[0035] FIG. 8 is a diagram during the formation of the mold 11 when each of the plurality of uneven portions 15 on the second slit 13 has a corner cube structure. In this case, a plurality of uneven mold frames 16c having a corner cube structure for punching out the second slit 13 are formed on the bottom surface 11c of the concave portion 11b of the mold 11. Each uneven mold frame 16c on the bottom surface 11c of the mold 11 has three surfaces (first to third surfaces 16d to 16f) with different angles of 90 degrees each. Cutting is performed with the cutting edge inclined along one of the directions of these three surfaces. In the example of FIG. 8, starting from the side closer to the center of the bottom surface 11c of the mold 11 and moving toward the outer periphery, cutting of the plurality of uneven mold frames 16c is sequentially performed with the cutting edge inclined along one of the three surfaces of the uneven mold frame 16c. Each arrow line in FIG. 8 indicates the cutting direction of the cutting edge, and the cutting edge is moved in the order of steps S1 to S5 while being inclined along the first surface 16d of the three surfaces (hereinafter, the first to third surfaces 16d to 16f) of the uneven mold frame 16c to perform cutting. Then, the direction of the cutting edge is changed, and the cutting edge is moved in the order of steps S6 to S10 while being inclined along the second surface 16e of the three surfaces of the uneven mold frame 16c to perform cutting. Then, the direction of the cutting edge is changed, and the cutting edge is moved in the order of steps S11 and S12 while being inclined along the third surface 16f of the three surfaces of the uneven mold frame 16c to perform cutting.

[0036] When performing the cutting in steps S1 to S5, when cutting with the cutting edge inclined along the first surface 16d of any uneven mold frame 16c of the mold frame 16b of the second slit 13 to be cut, the cutting edge also contacts the first surface 16d of the corresponding uneven mold frames 16c of the mold frames 16b of the two second slits 13 adjacent in the circumferential direction. However, since this first surface 16d is the surface that should be cut inherently, even if it is slightly cut due to the contact of the cutting edge, no problem occurs.

[0037] Similarly, when performing the cutting processes of steps S6 to S10, when the cutting edge is tilted and cutting is performed along the second surface 16e of any of the uneven molds 16c of the mold 16b of the second slit 13 to be cut, the cutting edge also contacts the corresponding second surfaces 16e of the uneven molds 16c of the mold 16b of two adjacent second slits 13 in the circumferential direction. However, since this second surface 16e is essentially the surface to be cut, even if it is slightly cut due to the contact of the cutting edge, no problem occurs.

[0038] In steps S11 and S12, the cutting edge is tilted along each third surface 16f of a plurality of uneven molds 16c in the mold 16b of the second slit 13 to be cut, and the plurality of third surfaces 16f are cut. Thus, in steps S11 and S12, the cutting edge does not contact the molds 16b of a plurality of adjacent second slits 13 in the circumferential direction, and the cutting edge contacts the third surfaces 16f of the plurality of uneven molds 16c in the mold 16b of the second slit 13 to be cut.

[0039] FIG. 9 is a diagram for explaining the inclination of the cutting edge 17. FIG. 9A shows the case where the cutting edge 17 is not inclined, and FIG. 9B shows the case where the cutting edge 17 is inclined. FIG. 10 is a diagram showing an example of processing the mold 16b of the second slit 13 to be cut with the cutting edge 17 inclined as in FIG. 9B. The case where the cutting edge 17 is not inclined means that the blade surface of the cutting edge 17 is arranged in the normal direction of the bottom surface 11c of the mold 11. The case where the cutting edge 17 is inclined means that the blade surface of the cutting edge 17 is inclined from the normal direction of the bottom surface 11c of the mold 11.

[0040] When the cutting edge 17 is not inclined as in FIG. 9A, when the cutting edge 17 is viewed in plan view, as shown in the right-side plan view of FIG. 9A, the area of the region 18 where the cutting edge 17 contacts the mold 11 becomes narrow. When the cutting edge 17 is inclined as in FIG. 9B, when the cutting edge 17 is viewed in plan view, as shown in the right-side plan view of FIG. 9B, the area where the cutting edge 17 contacts the mold 11 becomes larger than that in FIG. 9A, and the outer shape of the region 18 where the cutting edge 17 contacts the mold 11 becomes arc-shaped.

[0041] Therefore, as shown in FIG. 10, when machining the mold 16b of the second slit 13 to be cut with the cutting edge 17 inclined, although the cutting edge 17 also contacts the mold 16b of the second slit 13 adjacent in the circumferential direction, the cutting edge surface of the cutting edge 17 can be arranged along the same surface of the corresponding concavo-convex molds 16c. Even if the cutting edge 17 contacts the concavo-convex molds 16c of the mold 16b of the second slit 13 adjacent in the circumferential direction, there is no risk of damaging areas other than the original cutting locations of the mold 16b of each second slit 13.

[0042] When forming the mold 16b of the second slit 13 on the bottom surface 11c of the concave portion 11b of the mold 11 using the disk-shaped cutting edge 17, the cutting edge 17 may contact the molds 16b of three or more second slits 13 adjacent in the circumferential direction. Hereinafter, for the sake of simplicity of explanation, when the cutting edge 17 contacts the molds 16b of three second slits 13 adjacent in the circumferential direction, the conditions for the cutting edge 17 to contact the same surface of the corresponding concavo-convex molds 16c of these three molds 16b of the second slits 13 will be described below.

[0043] FIG. 11A is a plan view (left side) seen from the plane direction X and a plan view (right side) seen from above Z of the state where the cutting edge surface of the cutting edge 17 is inclined with respect to the normal direction of the bottom surface 11c of the concave portion 11b of the mold 11. FIG. 11B is a plan view seen from above Z showing the contact locations between the cutting edge 17 and the concavo-convex portions 15 of three second slits 13 adjacent in the circumferential direction.

[0044] As shown on the left side of FIG. 11A, when the cutting edge surface of the cutting edge 17 is inclined at an inclination angle β from the normal direction of the bottom surface 11c of the concave portion 11b of the mold 11, as shown on the right side of FIG. 11B, when viewed in plan from above Z, the cutting edge 17 becomes elliptical. Hereinafter, the ellipse corresponding to the cutting edge 17 will be represented by the long side a and the short side a×sinβ.

[0045] The equation of this ellipse is represented by the following formula (1).

Equation

[0046] Also, the inclination of the ellipse is represented by the following formula (2).

Number

[0047] To match the inclination of the ellipse with the pitch θp of the second slit 13, it is necessary to satisfy the following formula (3).

Number

[0048] When solving formula (3) for β, the following formula (4) is obtained.

Number

[0049] The corresponding surface position x of the concave and convex portions 15 of the second slit 13 adjacent in the circumferential direction is represented by the following formula (5).

Number

[0050] The inclination angle β of the cutting edge surface of the cutting edge 17 with respect to the normal direction of the bottom surface 11c of the concave portion 11b of the mold 11 is represented by formula (6) from formula (4) and formula (5).

Number

[0051] By inclining the cutting edge 17 at the inclination angle β represented by formula (6), the cutting edge 17 can be brought into contact with the same surface of each concave and convex mold 16c in the mold 16b of the three second slits 13 adjacent in the circumferential direction.

[0052] In practice, since cutting is performed with the cutting edge 17 obliquely with respect to the front and back directions of the paper surface of FIG. 11, there is a slight deviation from the calculated value of the above-described formula (6), but the above-described formula (6) can be used as an approximate formula.

[0053] As described above, the second slit 13 has a plurality of concavo-convex portions 15 arranged in the radial direction, and each concavo-convex portion 15 has first to third surfaces 16d to 16f that are different by 90 degrees from each other. A plurality of concavo-convex dies 16c for forming the concavo-convex portions 15 of the second slit 13 are also formed on the bottom surface 11c of the concave portion 11b of the mold 11. To form a plurality of concavo-convex dies 16c for the second slit 13 on the bottom surface 11c of the concave portion 11b of the mold 11, the cutting edge 17 is tilted at an inclination angle along the surface direction of each of the first to third surfaces 16d to 16f of each concavo-convex die 16c, and cutting is repeatedly performed.

[0054] FIG. 12 is a plan view showing an example of machining the central die 16b out of the dies 16b of three second slits 13 adjacent to each other in the circumferential direction.

[0055] First, as shown in FIG. 12A, cutting is performed with the cutting edge 17 tilted along the surface direction of the first surface 16d of an arbitrary concavo-convex die 16c in the die 16b of the central second slit 13. At this time, the cutting edge 17 also contacts the first surface 16d of the corresponding concavo-convex die 16c in the dies 16b of the two second slits 13 other than the center.

[0056] Next, as shown in FIG. 12B, cutting is performed with the cutting edge 17 tilted along the surface direction of the second surface 16e of the same concavo-convex die 16c in the die 16b of the central second slit 13. At this time, the cutting edge 17 also contacts the second surface 16e of the corresponding concavo-convex die 16c in the dies 16b of the two second slits 13 other than the center.

[0057] Next, as shown in FIG. 12C, cutting is performed with the cutting edge 17 tilted along the surface direction of the third surface 16f of the same concavo-convex die 16c in the die 16b of the central second slit 13. At this time, the cutting edge 17 also contacts the third surface 16f of the corresponding concavo-convex die 16c in the dies 16b of the two second slits 13 other than the center.

[0058] FIG. 13 is a plan view showing a die 16b of a plurality of second slits 13 formed along the circumferential direction on the bottom surface 11c of the concave portion 11b of the mold 11. FIG. 13 shows an example of forming the die 16b of the second slit 13 in order clockwise. The cutting edge 17 contacts the same surface of the corresponding concave-convex die 16c in the dies 16b of three second slits 13 adjacent to each other in the circumferential direction. Among the dies 16b of three second slits 13 adjacent to each other in the circumferential direction, the die 16b of the central second slit 13 is the die to be originally cut. While moving the cutting edge 17 in the radial direction from the center side to the outer peripheral side of this die and changing the orientation of the cutting edge 17, cutting is repeatedly performed along the first to third surfaces 16d to 16f of each of the plurality of concave-convex dies 16c. In FIG. 13A, among the five dies shown, the second die from the top is the die to be cut, and a total of three dies including the two dies above and below it are the dies that the cutting edge 17 contacts and is cut. When the formation of all the concave-convex dies 16c in the die 16b of the second slit 13 second from the top is completed, as shown in FIG. 13B, the third die 16b of the second slit 13 shifted clockwise by one position from the top becomes the object to be cut, and a total of three dies 16b of the second slit 13 including the two dies 16b of the second slit 13 above and below it are the dies that the cutting edge 17 contacts and is cut. When the formation of all the concave-convex dies 16c in the die 16b of the third second slit 13 from the top is completed, as shown in FIG. 13C, the fourth die 16b of the second slit 13 shifted clockwise by one position from the top becomes the object to be cut, and a total of three dies including the two dies 16b of the second slit 13 above and below it are the dies that the cutting edge 17 contacts and is cut.

[0059] In this way, the dies 16b of the plurality of second slits 13 formed along the circumferential direction on the bottom surface 11c of the concave portion 11b of the mold 11 are formed one by one with the cutting edge 17.

[0060] The optical scale 1 according to this embodiment can be incorporated into the distance measuring device 20. FIG. 14 is a block diagram showing a schematic configuration of the distance measuring device 20 including the optical scanning device 2 having the optical scale 1 according to this embodiment. As shown in FIG. 14, the distance measuring device 20 according to this embodiment includes a light projecting unit 21, a light control unit 22, a light receiving unit 23, a signal processing unit 24, and an image processing unit 25. Among these, the light projecting unit 21, the light control unit 22, the light receiving unit 23, and the signal processing unit 24 constitute the distance measuring device 26. At least a part of the distance measuring device 20 in FIG. 14 can be configured by one or more semiconductor ICs (Integrated Circuits). For example, the signal processing unit 24 and the image processing unit 25 may be integrated inside one semiconductor chip, or may be integrated including the light receiving unit 23 in this semiconductor chip. Further, it may be integrated including the light projecting unit 21 in this semiconductor chip.

[0061] The light projecting unit 21 projects the first light. The first light is, for example, laser light in a predetermined frequency band. Laser light is coherent light with aligned phase and frequency. The light projecting unit 21 intermittently projects the pulsed first light at a predetermined period. The period at which the light projecting unit 21 projects the first light is a time interval longer than the time required for the distance measuring device 26 to measure the distance based on one pulse of the first light.

[0062] The light projecting unit 21 includes an oscillator 31, a light projection control unit 32, a light source 33, a first drive unit 34, and a second drive unit 35. The oscillator 31 generates an oscillation signal corresponding to the period of projecting the first light. The first drive unit 34 intermittently supplies power to the light source 33 in synchronization with the oscillation signal. The light source 33 intermittently emits the first light based on the power from the first drive unit 34. The light source 33 may be a laser element that emits a single laser light, or a laser unit that emits a plurality of laser lights simultaneously. The light projection control unit 32 controls the second drive unit 35 in synchronization with the oscillation signal. The second drive unit 35 supplies a drive signal synchronized with the oscillation signal to the light control unit 22 according to an instruction from the light projection control unit 32.

[0063] The light control unit 22 controls the traveling direction of the first light emitted from the light source 33. The light control unit 22 includes a first lens 36, a beam splitter 37, a second lens 38, a half mirror 39, and an optical scanner 1 having an optical scale 1.

[0064] The first lens 36 condenses the first light emitted from the light projecting unit 21 and guides it to the beam splitter 37. The beam splitter 37 branches the first light from the first lens 36 in two directions and guides it to the second lens 38 and the half mirror 39. The second lens 38 guides the branched light from the beam splitter 37 to the light receiving unit 23. The reason for guiding the first light to the light receiving unit 23 is to detect the light projection timing at the light receiving unit 23. The half mirror 39 allows the branched light from the beam splitter 37 to pass through and guides it to the optical scale 1.

[0065] The optical scale 1 rotationally drives the polygon mirror 3 shown in FIG. 1 in synchronization with the drive signal from the second drive unit 35 in the light projecting unit 21. Thereby, the reflection direction of the branched light (first light) incident on the polygon mirror 3 of the optical scale 1 that has passed through the half mirror 39 is controlled. By rotationally driving the polygon mirror 3 of the optical scale 1 at a constant period, the first light emitted from the light control unit 22 can be scanned in at least a one-dimensional direction. FIG. 1 shows an example in which the first light projected from the distance measuring device 20 is scanned in the X direction, for example, by the optical scale 1. The first light is, for example, linear light extending in the Y direction.

[0066] When a distance measurement target object 30 such as a human or an object exists within the scanning range of the first light projected from the distance measuring device 20, the first light is reflected by the distance measurement target object 30. At least a part of the reflected light reflected by the distance measurement target object 30 is guided to the light receiving sensor 42 through the third lens 41 in the light receiving unit 23.

[0067] The light-receiving unit 23 includes a third lens 41, a light-receiving sensor 42, a photodetector 43, an amplifier 44, and an A / D converter 45. The photodetector 43 receives the light branched by the beam splitter 37 and converts it into an electrical signal. With the photodetector 43, the light projection timing of the first light can be detected. The amplifier 44 amplifies the electrical signal output from the photodetector 43.

[0068] The third lens 41 forms an image of the second light reflected by the half mirror 39 on the light-receiving sensor 42. The light-receiving sensor 42 receives the second light and converts it into an electrical signal. The light-receiving sensor 42 is composed of, for example, a SiPM (Silicon Photomultiplier).

[0069] The A / D converter 45 samples and A / D converts the electrical signal output from the light-receiving sensor 42 at a predetermined sampling rate to generate a digital signal.

[0070] The signal processing unit 24 measures the distance to the distance measurement object 30 that reflects the first light, and stores the digital signal corresponding to the second light in the storage unit 46. The signal processing unit 24 includes a storage unit 46, a distance measurement unit 47, and a control unit 48.

[0071] The distance measurement unit 47 measures the distance to the distance measurement object 30 based on the first light and the reflected light. More specifically, the distance measurement unit 47 measures the distance to the object based on the time difference between the light projection timing of the first light and the light reception timing of the reflected light included in the second light received by the light-receiving sensor 42. That is, the distance measurement unit 47 measures the distance based on the following formula (1).

[0072] Distance = speed of light × (light reception timing of reflected light - light projection timing of first light) / 2 …(1) More precisely, the "light reception timing of the reflected light" in formula (1) is the light reception timing of the peak position of the reflected light. The distance measurement unit 47 detects the peak position of the reflected light included in the second light based on the digital signal generated by the A / D converter 45.

[0073] By using the distance measuring device 20 shown in FIG. 14, the distance to the object 30 to be measured can be accurately measured. The distance measuring device 20 shown in FIG. 14 can be mounted on a vehicle and used for autonomous driving technology. Alternatively, the distance measuring device 20 shown in FIG. 14 can be mounted on a portable device such as a smartphone or a tablet, and can be applied to three-dimensional image display, VR (Virtual Reality), AR (Augmented Reality), and MR (Mixed Reality) technologies.

[0074] As described above, the optical scale 1 according to the present embodiment is integrally formed by a slit surface 1a on which one or more slit pairs 14 having a first slit 12 and a second slit 13 are arranged, and a polygon mirror 3. Alignment between the slit surface 1a and the polygon mirror 3 is not required, manufacturing becomes easy, and manufacturing costs can be reduced.

[0075] The first slit 12 reflects the light emitted by the light emitting element 5a of the encoder IC 5 in the direction of the light receiving element 5b, while the second slit 13 has a retroreflective structure that returns the light emitted by the light emitting element 5a of the encoder IC 5 in the direction of the light emitting element 5a. Therefore, the reflected light of the second slit 13 is not received by the light receiving element 5b of the encoder IC 5, and the rotation angle of the optical scale 1 can be accurately detected based on the number of times the light receiving element 5b receives light.

[0076] The optical scale 1 according to the present embodiment can be manufactured by injection molding using a mold 11 in which a mold for the polygon mirror 3 and the slit surface 1a is formed. A mold for the slit surface 1a is formed on the bottom surface 11c of the concave portion 11b of the mold 11. When forming this mold, among the molds 16b of the plurality of second slits 13 that extend radially from the center of the bottom surface 11c and are arranged in the circumferential direction, when the cutting edge 17 is brought into contact with and cut on any of the concave-convex molds 16c of the mold 16b of the second slit 13 to be cut, the cutting edge 17 is also brought into contact with the corresponding concave-convex molds 16c of the molds 16b of two or more second slits 13 adjacent in the circumferential direction. Thereby, the cutting operation can be performed without damaging the molds other than the mold 16b of the second slit 13 to be contacted.

[0077] [Supplementary Note] [Item 1] A slit surface on which one or more slit pairs having a first slit and a second slit, at least one of the reflectance or the reflection direction of which is different from each other, are arranged, and an optical member integrally joined to the slit surface and performing predetermined optical control. Optical scale. [Item 2] The predetermined optical control includes reflection, scattering, refraction, or absorption of incident light. The optical scale according to Item 1. [Item 3] The first slit reflects incident light in a direction corresponding to the incident direction, The second slit retroreflects incident light. The optical scale according to Item 1 or 2. [Item 4] The optical member has three or more mirror surfaces each connected to the slit surface and arranged in different directions. The optical scale according to any one of Items 1 to 3. [Item 5] The optical member is rotatable around a rotation axis, The slit surface and the three or more mirror surfaces rotate around the rotation axis. The optical scale according to Item 4. [Item 6] The first slit and the second slit extend radially from the rotation axis, The slit surface has a plurality of the slit pairs arranged circumferentially around the rotation axis. The optical scale according to Item 5. [Item 7] A plurality of the first slits and the second slits are alternately arranged in the circumferential direction around the rotation axis on the slit surface. The optical scale according to Item 6. [Item 8] The second slit has a plurality of concavo-convex portions arranged along the radial direction from the rotation axis. The optical scale according to any one of Items 5 to 7. [Item 9] Each of the plurality of concavo-convex portions has three surfaces arranged in directions intersecting each other, and is a corner cube structure that retroreflects incident light. The optical scale according to Item 8. [Item 10] Among the plurality of concavo-convex portions respectively included in each of three or more pairs of the slits adjacent to each other in the radial direction, a cutting blade for forming any one of the concavo-convex molds included in the mold of the slit pair to be cut among the molds of the three or more pairs of slits adjacent to each other in the circumferential direction at the bottom of the mold for integrally injection-molding the slit surface and the optical member is arranged to contact any one of the concavo-convex molds included in the molds of two or more pairs of slits adjacent to the slit pair to be cut. The optical scale according to Item 8 or 9. [Item 11] The optical scale according to any one of Items 1 to 9, which scans incident light within a predetermined angle range, and A first light receiving unit that receives reflected light from a distance measurement target that reflects the light scanned by the optical scale, and A distance measurement device including a distance measurement unit that measures the distance to the distance measurement target based on the time when the first light receiving unit receives the reflected light and the emission time of the incident light. [Item 12] Comprising a first light emitting unit that emits the incident light to the optical scale, The optical scale scans the light emitted from the first light emitting unit within the predetermined angle range. The distance measurement device according to Item 11. [Item 13] A second light emitting unit that irradiates light on the slit surface, and A second light receiving unit that receives the light reflected by the first slit from the light from the second light emitting unit, and An angle detection unit that detects the scanning angle of the optical scale based on the number of times light is received by the second light receiving unit. The distance measurement unit detects the direction of the object to be measured based on the scanning angle detected by the angle detection unit. The distance measuring device according to item 11 or 12. [Item 14] Prepare a mold having a recess with an inner wall surface along the outer shape of an optical scale in which a plurality of slit pairs having a first slit and a second slit, at least one of the reflectance or the reflection direction of which is different from each other, and an optical member that performs predetermined optical control are integrally molded. Fill the recess of the mold with a heated thermosetting resin material and cure it. Take out the cured resin from the mold. Mirror-finish at least a part of the surface of the resin. A method for manufacturing an optical scale. [Item 15] The first slit and the second slit included in each of the plurality of slit pairs extend radially from the center of the slit surface in the radial direction. The second slit has a plurality of uneven portions arranged alternately along the radial direction. A mold frame of the slit surface is provided on the bottom surface of the recess of the mold. A mold frame of a plurality of the slit pairs arranged in the circumferential direction of the bottom surface is provided on the mold frame of the slit surface. A plurality of uneven molds for forming the plurality of uneven portions are provided on the mold frame of each of the plurality of slit pairs. When forming any one of the uneven molds in the mold frame of the slit pair to be cut among the mold frames of three or more adjacent slit pairs in the circumferential direction, bring a cutting edge into contact with this uneven mold and the corresponding uneven molds in the mold frames of two or more adjacent slit pairs other than the slit pair to be cut. The method for manufacturing an optical scale according to item 14. [Item 16] Each of the uneven portions and the uneven molds has three surfaces arranged in directions intersecting each other. The cutting edge is arranged along the same one of the three surfaces respectively included in each of the three or more uneven-shaped frames corresponding to the three or more slit pairs. The method for manufacturing an optical scale according to item 15.

[0078] Aspects of the present disclosure are not limited to the individual embodiments described above, but also include various modifications that can be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the content described above. That is, various additions, changes, and partial deletions are possible without departing from the conceptual ideas and spirits of the present disclosure derived from the content defined in the claims and their equivalents.

Description of Reference Numerals

[0079] 1 Optical scale, 1a Slit surface, 2 Optical scanning device, 3 Polygon mirror, 3a Mirror surface, 4 Motor, 5a Light emitting element, 5b Light receiving element, 5c Rotation angle detection unit, 6 Rotation axis, 11 Mold, 11a Inner wall surface, 11b Recess, 11c Bottom surface, 11d Side surface, 12 First slit, 13 Second slit, 14 Slit pair, 15 Concavo-convex portion, 16 Mold frame, 16a Mold frame, 16b Mold frame, 16c Uneven-shaped mold frame, 16d First surface, 16e Second surface, 16f Third surface, 17 Cutting edge, 18 Region, 20 Distance measuring device, 21 Light projecting unit, 22 Light control unit, 23 Light receiving unit, 24 Signal processing unit, 25 Image processing unit, 26 Distance measurement device, 30 Distance measurement object, 31 Oscillator, 32 Light projection control unit, 33 Light source, 34 First drive unit, 35 Second drive unit, 36 First lens, 37 Beam splitter, 38 Second lens, 39 Half mirror, 41 Third lens, 42 Light receiving sensor, 43 Photodetector, 44 Amplifier, 45 A / D converter, 46 Storage unit, 47 Distance measurement unit, 48 Control unit, 100 Optical scale, 101 First reflection scale, 102 Second reflection scale, 102a Concavo-convex surface, 103 Scale surface, 105 Semiconductor layer, 106 Metal layer, 107 Mold, 107a Bottom surface, 108 Mold frame, 108 Uneven-shaped mold frame, 109 Cutting edge

Claims

1. A slit surface on which one or more slit pairs having a first slit and a second slit, at least one of the reflectance or the reflection direction of which is different from each other, are arranged; An optical member integrally joined to the slit surface and performing predetermined optical control. An optical scale.

2. The predetermined optical control includes reflection, scattering, refraction, or absorption of incident light. The optical scale according to claim 1.

3. The first slit reflects incident light in a direction corresponding to the incident direction. The second slit retroreflects incident light. The optical scale according to claim 1.

4. The optical member has three or more mirror surfaces each connected to the slit surface and arranged in different directions. The optical scale according to claim 1.

5. The optical member is rotatable around a rotation axis. The slit surface and the three or more mirror surfaces rotate around the rotation axis. The optical scale according to claim 4.

6. The first slit and the second slit extend radially from the rotation axis. The slit surface has a plurality of the slit pairs arranged circumferentially around the rotation axis. The optical scale according to claim 5.

7. On the slit surface, a plurality of the first slits and the second slits are alternately arranged in the circumferential direction around the rotation axis. The optical scale according to claim 6.

8. The second slit has a plurality of concavo-convex portions arranged along the radial direction from the rotation axis. The optical scale according to claim 5.

9. Each of the plurality of concavo-convex portions has three surfaces arranged in directions intersecting each other and has a corner cube structure for retroreflecting incident light. The optical scale according to claim 8.

10. Among the plurality of concavo-convex portions respectively included in three or more of the slit pairs adjacent to each other in the radial direction, a cutting edge for forming any one of the concavo-convex molds included in the mold of the slit pair to be cut among the molds of the three or more slit pairs adjacent to each other in the circumferential direction at the bottom of the mold for integrally injection-molding the slit surface and the optical member is arranged to contact any one of the concavo-convex molds included in the molds of two or more slit pairs adjacent to the slit pair to be cut. The optical scale according to claim 8.

11. An optical scale according to any one of claims 1 to 9, which scans incident light within a predetermined angular range. A first light receiving unit that receives reflected light from a distance measurement target that reflects the light scanned by the optical scale; A distance measurement device comprising: a distance measurement unit that measures the distance to the distance measurement target based on the time when the first light receiving unit receives the reflected light and the emission time of the incident light.

12. Comprising a first light emitting unit that emits the incident light to the optical scale, The optical scale scans the light emitted from the first light emitting unit within the predetermined angular range. The distance measurement device according to claim 11.

13. A second light emitting unit that irradiates light onto the slit surface; A second light receiving unit that receives the light reflected by the first slit from the light from the second light emitting unit; An angle detection unit that detects the scanning angle of the optical scale based on the number of times light is received by the second light receiving unit, and The distance measurement unit detects the direction of the distance measurement target based on the scanning angle detected by the angle detection unit. The distance measurement device according to claim 11.

14. Prepare a mold having a concave portion along the inner wall surface of the outer shape of the optical scale in which a plurality of slit pairs having first slits and second slits, at least one of the reflectance or the reflection direction of which is different from each other, and an optical member that performs predetermined optical control are integrally molded; Fill the concave portion of the mold with a heated thermosetting resin material and cure it; Remove the cured resin from the mold; Mirror-finish at least a part of the surface of the resin. A method for manufacturing an optical scale.

15. The first slit and the second slit included in each of the plurality of slit pairs extend radially from the center of the slit surface in the radial direction, The second slit has a plurality of uneven portions alternately arranged along the radial direction, A mold frame of the slit surface is provided on the bottom surface of the concave portion of the mold, A mold frame of a plurality of the slit pairs arranged in the circumferential direction of the bottom surface is provided on the mold frame of the slit surface, A plurality of uneven molds for forming the plurality of uneven portions are provided on the mold frame of each of the plurality of slit pairs, When forming any one of the uneven molds in the mold frame of the slit pair to be cut among the mold frames of three or more adjacent slit pairs in the circumferential direction, bring a cutting edge into contact with this uneven mold and the corresponding uneven molds in the mold frames of two or more adjacent slit pairs other than the slit pair to be cut. The method for manufacturing an optical scale according to claim 14.

16. The uneven portions and the uneven mold frame each have three surfaces arranged in directions intersecting with each other. The cutting edge is arranged along the same one of the three surfaces each of the three or more uneven mold frames corresponding to the three or more slit pairs has. The method for manufacturing an optical scale according to claim 15.

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