Light receiving element and rotation detector

Abstract

The objective of the present invention is to suppress signal distortion and reduce wasted space in a light receiving element. This light receiving element includes a plurality of light receiving portion groups (21g) arranged in an arrangement direction with a prescribed arrangement pitch. The light receiving portion groups (21g) include a first light receiving portion (211) and a second light receiving portion (212). The first light receiving portion (211) includes a first main phase portion and a first auxiliary phase portion having a width that is 1 / 3 of the arrangement pitch. The first light receiving portion (211) is separated into a first main body portion (211a) and a first separated portion (211b), of which the widths in the arrangement direction are each less than 1 / 4 of the arrangement pitch. The second light receiving portion (212) is separated into a second main body portion (212a) and a second separated portion (212b), of which the widths in the arrangement direction are each less than 1 / 4 of the arrangement pitch. The first main body portion (211a) and the second main body portion (212a) are arranged in the arrangement direction, and the first separated portion (211b) and the second separated portion (212b) are arranged in the arrangement direction.

Description

[Technical Field]

[0001] The present disclosure relates to a light receiving element and a rotation detector. [Background technology]

[0002] Conventionally, in rotation detectors or linear displacement detectors, there are known configurations that use optical means including a light emitting unit, a light receiving element, etc. For example, in the rotation detector described in Patent Document 1, in order to increase the resolution, an incremental pattern light receiving unit is formed by combining a photoelectric conversion element and a slit.

[0003] In addition, in the detector described in Patent Document 1, the width of the slit is set to 1 / 3 of the slit pitch, and two slits having such width are arranged with a mutual offset of 1 / 12 of the slit pitch, in an attempt to suppress distortion (deviation from a sine wave) of the signal obtained in the incremental light receiving section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent No. 5927482 Summary of the Invention

[0005] In the detector described in Patent Document 1, the maximum width of the slits is 5 / 12 of the slit pitch, which is greater than 1 / 4 of the slit pitch. Therefore, when the detector receives two signals with a phase difference of 90 degrees, which corresponds to 1 / 4 of the slit pitch, if two slits corresponding to the two signals are spaced apart at a distance of 1 / 4 of the slit pitch, the two slits will interfere with each other. This necessitates arranging the two slits at a pitch greater than 1 / 4 of the slit pitch (for example, a pitch of 5 / 4 of the slit pitch). This results in wasted space between the two slits. Therefore, it may not be possible to arrange a sufficient number of slits within a given space.

[0006] The present disclosure has been made to solve such problems, and aims to provide a light receiving element that can suppress signal distortion and reduce wasted space, and a rotation detector equipped with the same.

[0007] One aspect of the light-receiving element according to the present disclosure is a light-receiving element including a plurality of light-receiving unit groups arranged in a predetermined arrangement direction at a predetermined arrangement pitch. Each of the plurality of light-receiving unit groups includes a first light-receiving unit and a second light-receiving unit arranged at a position shifted from the first light-receiving unit in the arrangement direction by ¼ of the arrangement pitch. The first light-receiving unit includes a first main phase unit and a first sub-phase unit. The first main phase unit has a width of ⅓ of the arrangement pitch in the arrangement direction. The first sub-phase unit has a width of ⅓ of the arrangement pitch in the arrangement direction. The first sub-phase unit is arranged at a position shifted from the first main phase unit in the arrangement direction by ⅛ of the arrangement pitch in the arrangement direction and adjacent to the first main phase unit in a direction perpendicular to the arrangement direction. The second light-receiving unit includes a second main phase unit and a second sub-phase unit. The second main phase unit has a width of ⅓ of the arrangement pitch in the arrangement direction. The second sub-phase portion has a width of 1 / 3 of the arrangement pitch in the arrangement direction. The second sub-phase portion is positioned at a position shifted in the arrangement direction by 1 / 12 of the arrangement pitch with respect to the second main phase portion, and adjacent to the second main phase portion in the vertical direction. The first light receiving portion is separated into a first main portion and a first separation portion, each of which has a width in the arrangement direction less than 1 / 4 of the arrangement pitch. The first main portion and the first separation portion are arranged spaced apart in the vertical direction. The second light receiving portion is separated into a second main portion and a second separation portion, each of which has a width in the arrangement direction less than 1 / 4 of the arrangement pitch. The second main portion and the second separation portion are arranged spaced apart in the vertical direction. The first main portion and the second main portion are arranged in the arrangement direction, and the gap between the first main portion and the second main portion is less than 1 / 4 of the arrangement pitch. The first separation portions and the second separation portions are arranged in the arrangement direction, and the gap between the first separation portions and the second separation portions is less than ¼ of the arrangement pitch.

[0008] One aspect of the rotation detector according to the present disclosure comprises the above-mentioned light receiving element, a light emitting unit that emits light, and a rotating plate that is positioned opposite the light receiving element, and the light is irradiated onto the multiple light receiving unit groups via the rotating plate.

[0009] According to the present disclosure, it is possible to realize a light receiving element and a rotation detector that can suppress signal distortion and reduce wasted space. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of an electric motor including a rotation detector according to a first embodiment. [Figure 2] FIG. 2 is a plan view of a rotating plate included in the rotation detector according to the first embodiment. [Figure 3] FIG. 3 is an enlarged view of a part of a pattern portion of a rotating plate included in the rotation detector according to the first embodiment. [Figure 4] FIG. 4 is a plan view of the light receiving element according to the first embodiment. [Figure 5] FIG. 5 is a plan view showing the configuration of a light receiving unit group included in the light receiving element according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing a state in which the first main body portion and the first separation portion of the first light receiving unit included in the light receiving element according to the first embodiment are arranged on the same circumference. [Figure 7] FIG. 7 is a plan view showing the configuration of a first light receiving portion included in the light receiving element according to the second embodiment. [Figure 8] FIG. 8 is a plan view showing the configuration of a first light receiving portion included in the light receiving element according to the third embodiment. [Figure 9] FIG. 9 is a plan view illustrating a configuration of a first light receiving portion included in the light receiving element according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept of the present disclosure will be described as optional components.

[0012] It should be noted that each drawing is a schematic diagram and is not necessarily a precise illustration. In each drawing, the same reference numerals are used to designate components that are substantially the same as those in other drawings, and redundant explanations will be omitted or simplified.

[0013] (Embodiment 1) The light receiving element and rotation detector according to the first embodiment will be described.

[0014] [1-1. Overall structure] First, the overall configuration of the light receiving element and rotation detector according to this embodiment will be described with reference to FIG.

[0015] Fig. 1 is a cross-sectional view showing the configuration of an electric motor 1 equipped with a rotation detector 10 according to this embodiment. In Fig. 1, a cross section passing through a rotation axis A of the electric motor 1 is shown.

[0016] As shown in FIG. 1, the electric motor 1 mainly includes a motor frame 2, a stator 3, a rotor 4, a rotating shaft 5, a bearing 7, and a rotation detector 10.

[0017] The motor frame 2 is a housing that houses the stator 3, rotor 4, etc. The stator 3 is fixed to the inner surface of the motor frame 2. The rotor 4 is provided on the motor frame 2 via a bearing 7 so as to be rotatable relative to the stator 3.

[0018] The rotating shaft 5 is a rod-shaped member that is fixed to the inner surface of the rotor 4 and rotates around the rotation axis A. The rotating shaft 5 is rotatably fixed to the motor frame 2 via a bearing 7. For example, when power is supplied to the electric motor 1, the rotating shaft 5 rotates together with the rotor 4 around the rotation axis A as a rotation center based on the power. A rotation detector 10 is provided at one axial end of the rotating shaft 5. A load (not shown) that is rotationally driven by the rotation of the rotating shaft 5 is attached to the other axial end of the rotating shaft 5. For example, the rotating shaft 5 is made of a magnetic metal such as iron.

[0019] The bearing 7 is a member fixed to the motor frame 2 and supports the rotating shaft 5 rotatably relative to the motor frame 2. In FIG. 1, the bearing 7 is disposed near one end of the rotating shaft 5, but a bearing may also be disposed near the other end of the rotating shaft 5.

[0020] The rotation detector 10 detects the rotation of the detection object. Specifically, the rotation detector 10 detects the position (rotational position) of the detection object, the rotation direction of the detection object, the number of rotations of the detection object, etc. In this embodiment, the detection object is a rotating shaft 5. That is, the rotation detector 10 detects the position of the rotating shaft 5, the rotation direction of the rotating shaft 5, the number of rotations of the rotating shaft 5, etc.

[0021] As described above, the rotation detector 10 is provided at one end of the rotating shaft 5. The rotation detector 10 includes a light receiving element 20, a light emitting unit 14, and a rotating plate 40. In this embodiment, the rotation detector 10 further includes a substrate 12, a frame 6, a boss 8, a bolt 9, and a screw 13.

[0022] The frame 6 is a cylindrical member attached to the motor frame 2 so as to cover one axial end of the rotating shaft 5, the rotating plate 40, etc. In this embodiment, the frame 6 is fixed to the motor frame 2 together with the substrate 12 by screws 13.

[0023] The rotating plate 40 is fixed to the rotating shaft 5 via the boss 8 and is a plate that rotates around the rotation axis A, and has a main body 42 and a pattern portion 50. The main body 42 has a plate-like shape with its thickness direction along the rotation axis A. The main body 42 also has an annular shape when viewed from the direction along the rotation axis A. The main body 42 is attached to one end of the rotating shaft 5 in the axial direction and rotates together with the rotating shaft 5 around the rotation axis A. The axis of the main body 42 and the rotation axis A are aligned.

[0024] The pattern unit 50 is an optical modulation unit arranged on the path (i.e., optical path) of light propagating from the light emitter 14 to the light receiving element 20. In this embodiment, the pattern unit 50 is arranged between the edge of the main body 42 and the rotation axis A, at a position facing the light emitter 14 and the light receiving element 20. The pattern unit 50 has an optical modulation pattern formed on a circumference centered on the rotation axis A. In this embodiment, the pattern unit 50 has portions with high and low reflectance for light from the light emitter 14 formed in a predetermined pattern. The rotating plate 40 is made of, for example, stainless steel, and a low-reflectance coating is formed on the low-reflectance portions of the pattern unit 50. The detailed configuration of the pattern unit 50 will be described later.

[0025] The boss 8 is a member to which the rotating plate 40 is fixed. In this embodiment, a through hole is formed in the center of the boss 8. The boss 8 is fixed to the rotating shaft 5 by a bolt 9 inserted into the through hole, and rotates together with the rotating shaft 5 around the rotation axis A.

[0026] The bolt 9 is a member that fixes the boss 8 to the rotary shaft 5. In this embodiment, the bolt 9 is a hexagon socket head bolt.

[0027] The substrate 12 is a plate-like member disposed at a position facing the rotating plate 40 and spaced apart from the rotating plate 40. The light receiving element 20 and the light emitting unit 14 are disposed on the main surface of the substrate 12 facing the rotating plate 40. In this embodiment, the substrate 12 is fixed to the motor frame 2 via the frame 6 by screws 13.

[0028] The light-emitting unit 14 is a light source that emits light. The light-emitting unit 14 is disposed at a position facing the pattern unit 50 of the rotating plate 40. The configuration of the light-emitting unit 14 is not particularly limited as long as it can emit light. In this embodiment, the light-emitting unit 14 is a light-emitting diode and is disposed on the substrate 12. More specifically, the light-emitting unit 14 is disposed on the light-receiving element 20 disposed on the substrate 12. The light-emitting unit 14 may be included in the light-receiving element 20. In other words, the light-receiving element 20 may be provided with the light-emitting unit 14.

[0029] The light receiving element 20 is an element that receives light from the light emitting unit 14. The light from the light emitting unit 14 is irradiated onto the light receiving element 20 via the rotating plate 40. In this embodiment, the light from the light emitting unit 14 is reflected by the pattern portion 50 of the rotating plate 40 and is irradiated onto the light receiving element 20. The detailed configuration of the light receiving element 20 will be described later.

[0030] [1-2. Pattern structure] The detailed configuration of the pattern portion 50 of the rotating plate 40 included in the rotation detector 10 according to this embodiment will be described with reference to Figs. 2 and 3. Fig. 2 is a plan view of the rotating plate 40 included in the rotation detector 10 according to this embodiment. Fig. 2 is a plan view of the surface of the rotating plate 40 facing the light receiving element 20, as viewed from a direction along the rotation axis A. Fig. 3 is an enlarged view of a portion of the pattern portion 50 of the rotating plate 40 included in the rotation detector 10 according to this embodiment. Fig. 3 is an enlarged view of the inside of the dashed frame III shown in Fig. 2.

[0031] 2 and 3, the pattern portion 50 is disposed on the surface of the rotating plate 40 facing the light receiving element 20. The pattern portion 50 is disposed on a circumference centered on the rotation axis A. In the present embodiment, the pattern portion 50 has a first pattern portion 51, a second pattern portion 52, a third pattern portion 53, and a fourth pattern portion 54. The first pattern portion 51, the second pattern portion 52, the third pattern portion 53, and the fourth pattern portion 54 are disposed in this order from the edge side of the rotating plate 40.

[0032] As shown in FIG. 3, the first pattern portion 51 includes a plurality of low-reflection regions 51a. The plurality of low-reflection regions 51a are formed, for example, by a coating having low reflectivity for light from the light-emitting portion 14. The plurality of low-reflection regions 51a form an incremental pattern. The plurality of low-reflection regions 51a have the same rectangular (or fan-shaped) shape and are arranged at equal intervals on a circumference centered on the rotation axis A. The number of the plurality of low-reflection regions 51a is not particularly limited, but is 512 in this embodiment.

[0033] The second pattern portion 52 includes a plurality of low-reflection regions 52a. The plurality of low-reflection regions 52a are formed, for example, by a coating having low reflectivity for light from the light-emitting unit 14. The plurality of low-reflection regions 52a form an absolute pattern. In this embodiment, the plurality of low-reflection regions 52a are randomly arranged on a circumference of the rotating plate 40, the circumference being centered on the rotation axis A. The light-receiving element 20 can identify the absolute position of the rotating plate 40 in the circumferential direction, the circumference being centered on the rotation axis A, by receiving light from the light-emitting unit 14 modulated by the plurality of low-reflection regions 52a.

[0034] The third pattern portion 53 includes a plurality of low-reflection regions 53a. The plurality of low-reflection regions 53a are formed, for example, by a coating having low reflectivity for light from the light-emitting portion 14. The plurality of low-reflection regions 53a form an absolute pattern. In this embodiment, the plurality of low-reflection regions 53a are randomly arranged on a circumference of the rotating plate 40, centered on the rotation axis A, similar to the plurality of low-reflection regions 52a of the second pattern portion 52.

[0035] The fourth pattern portion 54 includes a plurality of low-reflection regions 54a. The plurality of low-reflection regions 54a are formed, for example, by a coating having low reflectivity for light from the light-emitting unit 14. The fourth pattern portion 54 is used to detect the rotation speed of the rotating plate 40. In this embodiment, the plurality of low-reflection regions 54a have an arc-like shape extending in the circumferential direction centered on the rotation axis A of the rotating plate 40. Each of the plurality of low-reflection regions 54a has an arc-like shape with a central angle of 180 degrees. The number of the plurality of low-reflection regions 54a is not particularly limited, but in this embodiment, the fourth pattern portion 54 includes four low-reflection regions 54a having arc-like shapes with different radii. The four low-reflection regions 54a are arranged at positions spaced 90 degrees apart from each other around the rotation axis A.

[0036] [1-3. Light receiving element configuration] The configuration of the light receiving element 20 will be described with reference to Fig. 4. Fig. 4 is a plan view of the light receiving element 20 according to this embodiment. Fig. 4 is a plan view of the surface of the light receiving element 20 facing the rotating plate 40, as viewed from a direction along the rotation axis A.

[0037] The light receiving element 20 is an element having a plurality of light receiving portions, each of which is an area for detecting light. The light receiving element 20 is, for example, a plate-shaped element having a semiconductor layer. Each of the plurality of light receiving portions of the light receiving element 20 is formed, for example, by adding impurities to the semiconductor layer. The light receiving element 20 includes an increment detection unit 21. In this embodiment, the light receiving element 20 further includes a first absolute detection unit 23, a second absolute detection unit 22, and a rotation speed detection unit 24.

[0038] The increment detection unit 21 is a light detection unit that outputs a detection signal in an incremental manner. Light from the light emitting unit 14 is irradiated onto the increment detection unit 21 mainly via the first pattern portion 51 of the rotating plate 40. The increment detection unit 21 includes a plurality of light receiving unit groups 21g that are arranged in a predetermined direction at positions spaced apart at regular intervals. In this embodiment, the plurality of light receiving unit groups 21g are arranged on a circumference centered on the rotation axis A. The detailed configuration of each of the plurality of light receiving unit groups 21g will be described later. Note that, hereinafter, the arrangement distance between two adjacent light receiving unit groups 21g is referred to as the arrangement pitch P0, and the direction in which the plurality of light receiving unit groups 21g are arranged is referred to as the arrangement direction. The arrangement direction is a direction along the circumference centered on the rotation axis A.

[0039] The first absolute detection unit 23 is a detection unit that outputs a detection signal in an absolute system. Light from the light-emitting unit 14 is irradiated onto the first absolute detection unit 23 mainly via the third pattern portion 53 of the rotating plate 40. The first absolute detection unit 23 has a plurality of first absolute light-receiving units 23a. The plurality of first absolute light-receiving units 23a are arranged on a first circumference of a first radius centered on the rotation axis A. The plurality of light-receiving unit groups 21g described above are arranged only on the outer diameter side (i.e., on the side farther from the rotation axis A than the plurality of first absolute light-receiving units 23a) of the inner diameter side and the outer diameter side relative to the plurality of first absolute light-receiving units 23a. The plurality of light-receiving unit groups 21g are arranged on a second circumference of a second radius that is concentric with the first circumference of the first radius on which the plurality of first absolute light-receiving units 23a are arranged and is greater than the first circumference. The first absolute light-receiving portions 23a and the light-receiving portion groups 21g do not overlap with each other.

[0040] The second absolute detection unit 22 is a detection unit that outputs a detection signal in an absolute system. Light from the light-emitting unit 14 is irradiated onto the second absolute detection unit 22 mainly via the second pattern portion 52 of the rotating plate 40. The second absolute detection unit 22 has a plurality of second absolute light-receiving units 22a. The plurality of second absolute light-receiving units 22a are concentric with the first circumference and are arranged on a fourth circumference having a fourth radius that is larger than the first radius and smaller than the second radius. The plurality of second absolute light-receiving units 22a do not overlap with the plurality of light-receiving unit groups 21g and the plurality of first absolute light-receiving units 23a.

[0041] The rotation speed detection unit 24 is a detection unit that outputs a detection signal corresponding to the rotation speed of the rotating plate 40. Light from the light emitter 14 is irradiated onto the rotation speed detection unit 24 mainly via the fourth pattern portion 54 of the rotating plate 40. The rotation speed detection unit 24 has one or more arc-shaped light-receiving units 24a. The arc-shaped light-receiving units 24a are concentric with the first circumference (i.e., centered on the rotation axis A) and arranged on a third circumference having a third radius smaller than the first radius. The width of the one or more arc-shaped light-receiving units 24a in the direction of the third circumference is greater than the width of each of the multiple first absolute light-receiving units 23a in the direction of the first circumference. In this embodiment, the rotation speed detection unit 24 has four arc-shaped light-receiving units 24a with different radii. The four arc-shaped light-receiving units 24a do not overlap with the first absolute light-receiving units 23a.

[0042] In this embodiment, the light emitting unit 14 is disposed in the light receiving element 20. The light emitting unit 14 is disposed between the first absolute detecting unit 23 and the second absolute detecting unit 22.

[0043] [1-4. Structure of the light receiving unit group] The plurality of light receiving unit groups 21g of the light receiving element 20 will be described with reference to Fig. 5. Fig. 5 is a plan view showing the configuration of the light receiving unit group 21g according to the present embodiment.

[0044] 5, the light receiving unit group 21g includes a first light receiving unit 211 and a second light receiving unit 212 that is shifted in the arrangement direction by ¼ of the arrangement pitch P0 with respect to the first light receiving unit 211. In the present embodiment, the light receiving unit group 21g further includes a third light receiving unit 213 and a fourth light receiving unit 214. The third light receiving unit 213 is shifted in the arrangement direction by ½ of the arrangement pitch P0 with respect to the first light receiving unit 211 and by ¼ of the arrangement pitch P0 with respect to the second light receiving unit 212. The fourth light receiving unit 214 is shifted in the arrangement direction by ¾ of the arrangement pitch P0 with respect to the first light receiving unit 211 and by ¼ of the arrangement pitch P0 with respect to the third light receiving unit 213. Light from the light emitter 14 is irradiated onto the light receiving unit group 21g mainly via the first pattern portion 51 of the rotating plate 40. As the rotating plate 40 rotates, the light from the light-emitting unit 14 is periodically intensity-modulated by the first pattern unit 51. As a result, the intensity of the light irradiated onto the light-receiving unit group 21g periodically fluctuates. The phases of the intensity modulation of the light irradiated onto the second light-receiving unit 212, the third light-receiving unit 213, and the fourth light-receiving unit 214 are shifted by 90 degrees, 180 degrees, and 270 degrees, respectively, from the phase of the intensity modulation of the light irradiated onto the first light-receiving unit 211.

[0045] The first light receiving unit 211 is separated into a first main body portion 211a and a first separation portion 211b, each having a width in the arrangement direction D1 that is less than ¼ of the arrangement pitch P0. The first main body portion 211a and the first separation portion 211b are spaced apart in a vertical direction D2 that is perpendicular to the arrangement direction D1. In this embodiment, the arrangement direction D1 is a direction along the circumference of a circle that is centered on the rotation axis A and passes through the multiple light receiving unit groups 21g. The vertical direction D2 is a radial direction of the circle that is centered on the rotation axis A.

[0046] The second light receiving portion 212 is separated into a second main body portion 212a and a second separation portion 212b whose width in the arrangement direction D1 is less than 1 / 4 of the arrangement pitch P0, and the second main body portion 212a and the second separation portion 212b are arranged apart in the vertical direction D2.

[0047] The third light receiving portion 213 is separated into a third main body portion 213a and a third separation portion 213b, each of which has a width in the arrangement direction D1 that is less than 1 / 4 of the arrangement pitch P0, and the third main body portion 213a and the third separation portion 213b are arranged at a distance from each other in the vertical direction D2.

[0048] The fourth light receiving portion 214 is separated into a fourth main body portion 214a and a fourth separation portion 214b, each of which has a width in the arrangement direction D1 that is less than 1 / 4 of the arrangement pitch P0, and the fourth main body portion 214a and the fourth separation portion 214b are arranged at a distance from each other in the vertical direction D2.

[0049] Here, the structure of first light receiving unit 211 will be described with reference to Fig. 6. Fig. 6 is a diagram showing a state in which first main body portion 211a and first separation portion 211b of first light receiving unit 211 according to the present embodiment are arranged on the same circumference.

[0050] 6, when the first main body portion 211a and the first separation portion 211b of the first light receiving portion 211 are arranged on the same circumference, the first light receiving portion 211 has a first main phase portion 211m and a first sub-phase portion 211s. The first main phase portion 211m has a width that is 1 / 3 of the arrangement pitch P0 in the arrangement direction D1. The first sub-phase portion 211s has a width that is 1 / 3 of the arrangement pitch P0 in the arrangement direction D1. The first sub-phase portion 211s is shifted in the arrangement direction D1 by 1 / 12 of the arrangement pitch P0 with respect to the first main phase portion 211m, and is disposed in a position adjacent to the first main phase portion 211m in the vertical direction D2.

[0051] Because the first main phase portion 211m of the first light receiving portion 211 has a width of 1 / 3 of the arrangement pitch P0 in the arrangement direction D1, when the rotating plate 40 rotates, the first main phase portion 211m outputs a periodic signal with a trapezoidal waveform. Similarly, the first sub-phase portion 211s also outputs a periodic signal with a trapezoidal waveform. Furthermore, because the first sub-phase portion 211s is positioned at a position shifted by 1 / 12 of the arrangement pitch P0 in the arrangement direction D1 with respect to the first main phase portion 211m, the signal output by the first sub-phase portion 211s is shifted in phase by 30 degrees (i.e., 360 degrees / 12) with respect to the signal output by the first main phase portion 211m. The signal output by the first light receiving portion 211 is the sum of the signal output by the first main phase portion 211m and the signal output by the first sub-phase portion 211s. Therefore, the waveform of the signal output from the first light receiving section 211 is a waveform that is a combination of two trapezoidal waves, and is closer to a sine wave than a trapezoidal wave, that is, has less distortion.

[0052] Similar to the first light receiving section 211, the second light receiving section 212 also has a second main phase section and a second sub-phase section when the second main body section 212a and the second separation section 212b are arranged on the same circumference. The second main phase section has a width of 1 / 3 of the arrangement pitch P0 in the arrangement direction D1. The second sub-phase section has a width of 1 / 3 of the arrangement pitch P0 in the arrangement direction D1. The second sub-phase section is shifted in the arrangement direction D1 by 1 / 12 of the arrangement pitch P0 with respect to the second main phase section, and is positioned adjacent to the second main phase section in the vertical direction D2.

[0053] Similarly, the third light receiving section 213 has a third main phase portion and a third sub-phase portion, and the fourth light receiving section 214 has a fourth main phase portion and a fourth sub-phase portion.

[0054] This allows each of the light receiving unit groups 21g to suppress distortion in the output signal, thereby enabling the light receiving element 20 to detect the position of the rotating plate 40 in the rotation direction with higher accuracy.

[0055] 6, in order to arrange the first light receiving portion 211 and the second light receiving portion 212 in the arrangement direction D1 so that they do not overlap, the position of the second light receiving portion 212 in the arrangement direction D1 needs to be shifted by more than ⅓ of the arrangement pitch P0 relative to the first light receiving portion 211. Here, in order to output from the second light receiving portion 212 a signal that is phase-shifted by 90 degrees relative to the signal output by the first light receiving portion 211, the position of the second light receiving portion 212 needs to be shifted by ⅔ of the arrangement pitch P0 relative to the first light receiving portion 211 in the arrangement direction D1. As a result, a wasted space where no light receiving portion is arranged is generated between the first light receiving portion 211 and the second light receiving portion 212, over a length of 1 1 / 12 of the arrangement pitch P0.

[0056] In the light receiving unit group 21g according to the present embodiment, as described above, the first light receiving unit 211 is separated into a first main body portion 211a and a first separation portion 211b, each of which has a width in the arrangement direction D1 that is less than ¼ of the arrangement pitch P0, and the first main body portion 211a and the first separation portion 211b are spaced apart in the vertical direction D2. The second light receiving unit 212 is separated into a second main body portion 212a and a second separation portion 212b, each of which has a width in the arrangement direction D1 that is less than ¼ of the arrangement pitch P0, and the second main body portion 212a and the second separation portion 212b are spaced apart in the vertical direction D2. This allows the second main body portion 212a to be positioned at a position shifted by ¼ of the arrangement pitch P0 from the position of the first main body portion 211a in the arrangement direction D1, as shown in FIG. 5 . Furthermore, the second separation portion 212b can be disposed at a position shifted by ¼ of the arrangement pitch P0 in the arrangement direction D1 from the position of the first separation portion 211b. The first main body portion 211a and the second main body portion 212a are arranged in the arrangement direction D1, and the gap between the first main body portion 211a and the second main body portion 212a is less than ¼ of the arrangement pitch P0. The first separation portion 211b and the second separation portion 212b are arranged in the arrangement direction D1, and the gap between the first separation portion 211b and the second separation portion 212b is less than ¼ of the arrangement pitch P0. Therefore, the wasted space between the first light receiving portion 211 and the second light receiving portion 212 can be reduced.

[0057] 5, in the present embodiment, the third light receiving section 213 and the fourth light receiving section 214 have the same configuration as the first light receiving section 211 and the second light receiving section 212. Therefore, the third light receiving section 213 and the fourth light receiving section 214 also have the same effects as the first light receiving section 211 and the second light receiving section 212.

[0058] (Embodiment 2) A light receiving element according to embodiment 2 will be described. The light receiving element according to this embodiment differs from the light receiving element 20 according to embodiment 1 in the shapes of the main body and separation parts of each light receiving unit. The light receiving element according to this embodiment will be described below with reference to FIG. 7, focusing on the differences from the light receiving element 20 according to embodiment 1.

[0059] Fig. 7 is a plan view showing the configuration of a first light receiving portion 1211 included in a light receiving element according to this embodiment. Each of the multiple light receiving portion groups of the light receiving element according to this embodiment has a first light receiving portion 1211 shown in Fig. 7. Similar to first light receiving portion 211 according to embodiment 1, first light receiving portion 1211 is separated into a first main body portion 1211a and a first separation portion 1211b, each of which has a width in arrangement direction D1 that is less than ¼ of the arrangement pitch P0.

[0060] In the present embodiment, the edge of first main body portion 1211a on the first separation portion 1211b side (i.e., the right side in FIG. 7) and the edge of first separation portion 1211b on the first main body portion 1211a side (i.e., the left side in FIG. 7) are inclined with respect to arrangement direction D1 and vertical direction D2. A light receiving element having first light receiving portion 1211 with such a configuration also achieves the same effects as light receiving element 20 according to embodiment 1.

[0061] Furthermore, in the light receiving element according to this embodiment, first main body portion 1211a and first separation portion 1211b have an overlapping portion when viewed from vertical direction D2. Here, the overlapping portion between first main body portion 1211a and first separation portion 1211b when viewed from vertical direction D2 is the portion sandwiched between two dotted lines in Fig. 7. In this embodiment, a rectangular light receiving portion can be formed by combining the portion of first main body portion 1211a that overlaps with first separation portion 1211b and the portion of first separation portion 1211b that overlaps with first main body portion 1211a when viewed from vertical direction D2. In other words, the sum of the dimension of first main body portion 1211a in the vertical direction D2 at the portion where first main body portion 1211a and first separation portion 1211b overlap in arrangement direction D1 and the dimension of first separation portion 1211b in the vertical direction D2, as viewed from the vertical direction D2, is equal to the maximum dimension of first main body portion 1211a in the vertical direction D2. The dimension of first main body portion 1211a in the vertical direction D2 at the portion where first main body portion 1211a and first separation portion 1211b overlap in arrangement direction D1 as viewed from the vertical direction D2 refers to, for example, dimension L1 at the portion where first main body portion 1211a intersects with the dashed line in FIG. 7. Furthermore, the dimension of first separation portion 1211b in the vertical direction D2 refers to, for example, dimension L2 at the portion where first separation portion 1211b intersects with the dashed line in FIG. 7. 7. That is, L1+L2=L0. This allows the first light receiving unit 1211 to output a signal similar to that of the first light receiving unit 211 according to the first embodiment.

[0062] When the first main body portion 1211a and the first separation portion 1211b are separated, as in the first light receiving unit 1211 according to the present embodiment, the positions of the first main body portion 1211a and the first separation portion 1211b in the arrangement direction D1 may be slightly misaligned due to manufacturing errors or the like. Even when such misalignment occurs, in the first light receiving unit 1211 according to the present embodiment, the first main body portion 1211a and the first separation portion 1211b have an overlapping portion when viewed from the vertical direction D2. This prevents a decrease in the intensity of the output signal when light is irradiated to a position near the boundary between the first main body portion 1211a and the first separation portion 1211b in the arrangement direction D1. This prevents distortion of the output signal from the first light receiving unit 1211.

[0063] Although only the first light receiving section 1211 has been described for the light receiving element of this embodiment, the second light receiving section, the third light receiving section, and the fourth light receiving section of the light receiving element light receiving section group may also have a configuration similar to that of the first light receiving section 1211.

[0064] (Embodiment 3) A light receiving element according to embodiment 3 will be described. The light receiving element according to this embodiment differs from the light receiving element according to embodiment 2 in the shapes of the main body and separation parts of each light receiving unit. The light receiving element according to this embodiment will be described below with reference to FIG. 8, focusing on the differences from the light receiving element according to embodiment 2.

[0065] Fig. 8 is a plan view showing the configuration of first light receiving portion 2211 included in the light receiving element according to this embodiment. Each of the multiple light receiving portion groups of the light receiving element according to this embodiment has first light receiving portion 2211 shown in Fig. 8. Like first light receiving portion 1211 according to embodiment 2, first light receiving portion 2211 is separated into first main body portion 2211a and first separation portion 2211b, each of which has a width in arrangement direction D1 that is less than ¼ of arrangement pitch P0.

[0066] In this embodiment, first main body portion 2211a has a convex portion 2211p formed on its edge on the first separation portion 2211b side (i.e., the right side in Figure 8), and first separation portion 2211b has a concave portion 2211q formed on its edge on the first main body portion 2211a side (i.e., the left side in Figure 8).

[0067] Similarly to the light receiving element according to the second embodiment, the first main body portion 2211a and the first separation portion 2211b overlap with each other when viewed from the vertical direction D2. The overlapping portion between the first main body portion 2211a and the first separation portion 2211b is the portion sandwiched between two dotted lines in FIG. 8. In this embodiment, a rectangular light receiving unit can be formed by combining the portion of the first main body portion 2211a that overlaps with the first separation portion 2211b and the portion of the first separation portion 2211b that overlaps with the first main body portion 2211a when viewed from the vertical direction D2. That is, the recessed portion 2211q and the protruding portion 2211p have the same shape and size. Therefore, the area of ​​the recessed portion 2211q is equal to the area of ​​the protruding portion 2211p. This allows the first light receiving unit 2211 to output a signal similar to that of the first light receiving unit 211 according to the first embodiment.

[0068] In the present embodiment, first main body portion 2211a has convex portion 2211p and first separation portion 2211b has concave portion 2211q, but the configuration of first light receiving portion 2211 is not limited to this. For example, the first main body portion may have a concave portion formed on an edge on the first separation portion side, and the first separation portion may have a concave portion formed on an edge on the first main body portion side.

[0069] Furthermore, although only the first light receiving section 2211 has been described for the light receiving element according to this embodiment, the second light receiving section, the third light receiving section, and the fourth light receiving section of the light receiving section group of the light receiving element may also have a configuration similar to that of the first light receiving section 2211.

[0070] (Fourth embodiment) A light receiving element according to embodiment 4 will be described. The light receiving element according to this embodiment differs from the light receiving element according to embodiment 3 in the positional relationship between the convex portion and the concave portion. The light receiving element according to this embodiment will be described below with reference to FIG. 9, focusing on the differences from the light receiving element according to embodiment 3.

[0071] Fig. 9 is a plan view showing the configuration of first light receiving portion 3211 included in the light receiving element according to the present embodiment. As shown in Fig. 9, each of the multiple light receiving portion groups of the light receiving element according to the present embodiment has first light receiving portion 3211. Similar to first light receiving portion 2211 according to embodiment 3, first light receiving portion 3211 is separated into first main body portion 3211a and first separation portion 3211b, each of which has a width in arrangement direction D1 that is less than ¼ of arrangement pitch P0.

[0072] In this embodiment, the first main body portion 3211a has a convex portion 3211p formed on its edge on the first separation portion 3211b side (i.e., the right side in Figure 9), and the first separation portion 3211b has a concave portion 3211q formed on its edge on the first main body portion 3211a side (i.e., the left side in Figure 9).

[0073] Furthermore, in the light receiving element according to the present embodiment, first main body portion 3211a and first separation portion 3211b have an overlapping portion when viewed from vertical direction D2, similar to the light receiving element according to embodiment 3. Here, the overlapping portion between first main body portion 3211a and first separation portion 3211b when viewed from vertical direction D2 is the portion sandwiched between two dotted lines in FIG.

[0074] In this embodiment, when viewed from the vertical direction D2, a rectangular light receiving unit cannot be formed by combining the portion of first main body portion 3211a that overlaps with first separation portion 3211b and the portion of first separation portion 3211b that overlaps with first main body portion 3211a. That is, the position of convex portion 3211p in the vertical direction D2 does not correspond to the position of concave portion 3211q in the vertical direction D2. However, concave portion 3211q and convex portion 3211p have the same shape and size. Therefore, the area of ​​concave portion 3211q is equal to the area of ​​convex portion 3211p. The first light receiving unit 3211 having such convex portion 3211p and concave portion 3211q also achieves the same effect as the first light receiving unit 2211 according to the third embodiment.

[0075] Note that recess 3211q and protrusion 3211p do not necessarily have to have the same shape or size as long as they have the same area. For example, in the example shown in FIG. 9, recess 3211q and protrusion 3211p have a rectangular shape, but these shapes are not limited to a rectangle. For example, recess 3211q may be rectangular and protrusion 3211p may be a parallelogram. As described above, first main body portion 3211a and first separation portion 3211b only need to be configured so that when first main body portion 3211a and first separation portion 3211b are arranged in arrangement direction D1, their outer shapes are the same and the total areas of first main body portion 3211a and first separation portion 3211b are the same.

[0076] In the present embodiment, first main body portion 3211a has convex portion 3211p and first separation portion 3211b has concave portion 3211q, but the configuration of first light receiving portion 3211 is not limited to this. For example, first main body portion may have a concave portion formed on an edge on the first separation portion side, and first separation portion may have a concave portion formed on an edge on the first main body portion side.

[0077] Furthermore, although only the first light receiving section 3211 has been described for the light receiving element of this embodiment, the second light receiving section, the third light receiving section, and the fourth light receiving section of the light receiving section group of the light receiving element may also have a configuration similar to that of the first light receiving section 3211.

[0078] (Variation) Although the light receiving element and rotation detector according to the present disclosure have been described above based on the embodiments, the present disclosure is not limited to the above-described embodiments.

[0079] For example, in each of the above embodiments, the rotating plate 40 has a pattern portion that reflects a portion of the light from the light-emitting unit 14, but the configuration of the pattern portion is not limited to this. For example, the pattern portion may be a slit that transmits a portion of the light from the light-emitting unit 14. In this case, the rotating plate is disposed between the light-emitting unit 14 and the light-receiving unit.

[0080] In addition, in each of the above embodiments, the multiple light receiving portion groups of the light receiving element are arranged on a circumference centered on the rotation axis A to detect the amount of rotation of the rotating plate, but the configuration of the multiple light receiving portion groups is not limited to this. For example, the multiple light receiving portion groups and the multiple low-reflection areas of the first pattern portion may be arranged on a straight line to form a linear displacement detector (encoder).

[0081] In addition, this disclosure also includes forms obtained by making various modifications to the above embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions in each embodiment within the scope of the present disclosure. [Industrial Applicability]

[0082] The technology of the present disclosure can be used in a rotation detector that detects the amount of rotation of an electric motor or the like, or a linear displacement detector that detects the displacement of a linearly driven moving stage or the like. [Explanation of symbols]

[0083] 1 electric motor 2 Motor Frame 3 Stator 4 rotors 5 Rotation Axis 6 frames 7 Bearings 8. Boss 9 volts 10 Rotation detector 12 PCB 13 screws 14 Light-emitting part 20 Photodetector 21 Increment detection unit 21g Photodetector group 22 Second absolute detector 22a Second absolute light receiving part 23 First absolute detector 23a First absolute light receiving part 24 Rotation speed detector 24a Arc-shaped light receiving part 40 Rotating Plate 42 Main Unit 50 Pattern section 51 First pattern section 51a, 52a, 53a, 54a Low reflection area 52 Second pattern section 53 Third pattern section 54 Fourth Pattern Section 211, 1211, 2211, 3211 First light receiving section 211a, 1211a, 2211a, 3211a First main body 211b, 1211b, 2211b, 3211b First separation section 211m 1st main phase section 211s First sub-phase section 212 Second light receiving section 212a Second body part 212b Second separation section 213 Third light receiving section 213a Third body part 213b Third separation section 214 Fourth light receiving section 214a Fourth body part 214b Fourth separation section 2211p, 3211p convex part 2211q, 3211q recess

Claims

1. A light receiving element including a plurality of light receiving unit groups arranged in a predetermined arrangement direction at a predetermined arrangement pitch, each of the plurality of light receiving unit groups includes a first light receiving unit and a second light receiving unit that is shifted relative to the first light receiving unit by ¼ of the arrangement pitch in the arrangement direction; The first light receiving unit a first main phase portion having a width that is 1 / 3 of the arrangement pitch in the arrangement direction; a first sub-phase portion having a width of ⅓ of the arrangement pitch in the arrangement direction, shifted by ⅛ of the arrangement pitch with respect to the first main phase portion in the arrangement direction, and disposed at a position adjacent to the first main phase portion in a perpendicular direction perpendicular to the arrangement direction, The second light receiving unit is a second main phase portion having a width that is 1 / 3 of the arrangement pitch in the arrangement direction; a second sub-phase portion having a width that is ⅓ of the arrangement pitch in the arrangement direction, shifted by ⅛ of the arrangement pitch in the arrangement direction with respect to the second main phase portion, and disposed at a position adjacent to the second main phase portion in the vertical direction, the first light receiving portion is separated into a first main body portion and a first separation portion, each of which has a width in the arrangement direction less than ¼ of the arrangement pitch, and the first main body portion and the first separation portion are arranged to be spaced apart in the vertical direction; the second light receiving portion is separated into a second main body portion and a second separation portion, each of which has a width in the arrangement direction that is less than ¼ of the arrangement pitch, and the second main body portion and the second separation portion are arranged to be spaced apart in the vertical direction; the first body portion and the second body portion are arranged in the arrangement direction, and a gap between the first body portion and the second body portion is less than ¼ of the arrangement pitch; the first separation portion and the second separation portion are arranged in the arrangement direction, and a gap between the first separation portion and the second separation portion is less than ¼ of the arrangement pitch. Photodetector.

2. When viewed from the vertical direction, the first main body portion and the first separation portion have an overlapping portion. The light-receiving element according to claim 1 .

3. an edge of the first main body portion on the first separation portion side and an edge of the first separation portion on the first main body portion side are inclined with respect to the arrangement direction and the vertical direction; The light-receiving element according to claim 2 .

4. the first main body portion has a convex portion formed on an edge on the first separation portion side, The first separation portion has a recess formed on an edge on the first main body portion side. The light-receiving element according to claim 2 or 3.

5. the first main body portion has a recess formed on an edge on the first separation portion side, The first separation portion has a convex portion formed on an edge on the first main body portion side. The light-receiving element according to claim 2 or 3.

6. The area of ​​the recess is equal to the area of ​​the protrusion. The light-receiving element according to claim 4 .

7. The recessed portion and the protruding portion have the same shape and size. The light-receiving element according to claim 4 .

8. When viewed from the vertical direction, at a position in the arrangement direction where the first main body portion and the first separation portion overlap, the sum of the vertical dimension of the first main body portion and the vertical dimension of the first separation portion is equal to the maximum dimension of the first main body portion in the vertical direction. The light-receiving element according to claim 2 .

9. The light receiving element according to claim 1 ; a light emitting unit that emits light; a rotating plate disposed at a position facing the light receiving element, The light is irradiated onto the plurality of light receiving unit groups via the rotating plate. Rotation detector.

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