Optical encoder

Abstract

The present invention aims to improve the insufficient light reception in the light receiving portion. An optical encoder (1) includes a light source (2), a reflection portion (3), and a light receiving portion (4). The reflection portion (3) has a plurality of reflection regions (30) including an M code region (R1), and reflects light from the light source (2) through a region corresponding to n bits in the M code region (R1). The light receiving portion (4) receives the incident of the reflected light (C2) from the reflection portion (3) and photoelectrically converts the reflected light (C2). The M code region (R1) has a first face (31) corresponding to first code information (B1) and a second face (32) corresponding to second code information (B2) and having a different inclined structure (D1) from the first face (31). The light receiving portion (4) has a first light receiving group (41) and a second light receiving group (42). The first light receiving group (41) includes a plurality of first light receiving elements (401) that receive the reflected light (C2) from the first face (31). The second light receiving group (42) includes a plurality of second light receiving elements (402) that receive the reflected light (C2) from the second face (32). The positions of the first light receiving elements (401) and the positions of the second light receiving elements (401) are staggered in one direction.

Description

Technical Field

[0001] This invention generally relates to optical encoders. More specifically, this invention relates to reflective optical encoders. Background Technology

[0002] Patent Document 1 discloses a reflective optical encoder. This reflective optical encoder includes a light source, a reflective scale, a light detection unit, and a calculation unit. The reflective scale is a circular plate attached to a rotating shaft that is the object being measured. In this reflective optical encoder, reflected light from two first reflective portions of the reflective scale is received by two first light-receiving portions of the light detection unit. Furthermore, in this reflective optical encoder, reflected light from two second reflective portions having an inclination different from the first reflective portions is received by two second light-receiving portions of the light detection unit. The calculation unit performs calculations based on the outputs of the first and second light-receiving portions.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-145118 Summary of the Invention

[0006] Generally, reflective optical encoders are easier to make thinner overall than transmissive optical encoders. However, in reflective optical encoders, the amount of light received by the light-receiving section is often small. In particular, functions to counteract phase shifts in the received signal or to detect errors caused by foreign objects may lead to decreased photosensitivity due to insufficient light reception in the light-receiving section.

[0007] The present invention was made in view of the above circumstances, and its object is to provide an optical encoder that helps to improve the insufficient light received in the light-receiving part.

[0008] An optical encoder according to one aspect of the present invention includes a light source, a reflective portion, and a light-receiving portion. The reflective portion has a plurality of reflective regions, the plurality of reflective regions including a plurality of M-code regions arranged in a row according to a specific bit pattern representing an M-code. The reflective portion is configured to move along with the movement of an object and is configured to reflect light from the light source through one or more regions corresponding to n bits of the plurality of M-code regions, where n is a natural number. The light-receiving portion is configured to receive the reflected light from the reflective portion for photoelectric conversion. The plurality of M-code regions have a first surface corresponding to a first code information that is one of the bit information of the M-code, and a second surface corresponding to a second code information that is another bit information of the M-code. The second surface has a tilt structure different from the tilt structure of the first surface. The light-receiving portion has a first light-receiving group and a second light-receiving group. The first light-receiving group includes a plurality of first light-receiving elements arranged in one direction to receive reflected light reflected from the first surface. The second light-receiving group is arranged on a side farther from the reflective portion than the first light-receiving group. The second light-receiving group includes a plurality of second light-receiving elements arranged along the one direction to receive reflected light reflected from the second surface. The first and second light-receiving groups are arranged such that the positions of the first and second light-receiving elements are offset from each other in the one direction.

[0009] According to another aspect of the present invention, an optical encoder includes a light source, a reflector, and a light-receiving unit. The reflector has a plurality of reflective regions, which include a plurality of code regions arranged in a row according to a specific positioning pattern. The reflector is configured to move along with the movement of an object and is configured to reflect light from the light source through one or more regions corresponding to n bits of the plurality of code regions, where n is a natural number. The light-receiving unit is configured to receive the reflected light from the reflector for photoelectric conversion. The reflector includes three or more types of reflective regions having different tilt structures. The light-receiving unit has three or more light-receiving groups corresponding to and receiving light from the three or more types of reflective regions, respectively. Attached Figure Description

[0010] Figure 1 A is a schematic perspective view of the main part of the optical encoder according to an embodiment;

[0011] Figure 1 B is a schematic perspective view of the measuring object and a portion of the rotating plate of the optical encoder according to this embodiment;

[0012] Figure 2This is a diagram illustrating the positional relationship between the reflective portion and the light-receiving portion of an optical encoder according to this embodiment;

[0013] Figure 3 This is a diagram illustrating the process for manufacturing the reflective portion of an optical encoder according to this embodiment;

[0014] Figure 4 This is a schematic diagram of the reflective section according to a comparative example, illustrated to explain the advantages of the optical encoder according to this embodiment;

[0015] Figure 5 Figures A to C are illustrations of the tilted structure of the reflective portion of the optical encoder according to the first modified example of this embodiment;

[0016] Figure 6 This is a diagram illustrating the positional relationship between the reflective portion and the light-receiving portion of an optical encoder according to a second variation of this embodiment;

[0017] Figure 7 This is a diagram illustrating the positional relationship between the reflective portion and the light-receiving portion of an optical encoder according to a third variation of this embodiment;

[0018] Figure 8 This is a diagram illustrating the positional relationship between the reflective part and the light-receiving part of an optical encoder according to a fourth modified example of this embodiment;

[0019] Figure 9 This is a diagram illustrating the positional relationship between the reflective part and the light-receiving part of an optical encoder according to a fifth modified example of this embodiment;

[0020] Figure 10 This is a diagram illustrating the positional relationship between the reflective and light-receiving portions of an optical encoder in another application of a fifth variation of this embodiment;

[0021] Figure 11 This is a diagram illustrating the positional relationship between the reflective and light-receiving portions of an optical encoder in another application of the fifth variation of this embodiment;

[0022] Figure 12 This is a schematic side view of the reflective portion of an optical encoder according to one of the other variations of this embodiment;

[0023] Figure 13 A and B are schematic side views of the reflective portion of an optical encoder in some other variations of this embodiment;

[0024] Figure 14 This is a schematic cross-sectional view of the main part of the optical encoder according to the sixth variation of this embodiment; and

[0025] Figure 15This is a diagram illustrating the positional relationship between the reflective part and the light-receiving part of an optical encoder according to a sixth variation of this embodiment. Detailed Implementation

[0026] (Example)

[0027] Now refer to Figure 1 A to Figure 3 The optical encoder 1 according to an embodiment will be described below. All the accompanying drawings to be referenced in the following description of the embodiments, etc., are schematic diagrams. That is, the aspect ratios (including thicknesses) of the various constituent elements illustrated in the drawings do not always reflect the actual aspect ratios of these constituent elements.

[0028] (1) Overview

[0029] First, refer to Figure 1 A to Figure 2 This section provides an overview of the optical encoder 1 according to this embodiment.

[0030] As an example, according to one aspect of this embodiment, the optical encoder 1 is a rotary encoder, and the object of the optical encoder 1 (measurement object OB1) is a rotor (reference). Figure 1 (B). The optical encoder 1 can be, for example, built into a servo motor and configured to measure the rotational movement (rotation angle or rotational position) of the rotating shaft of the servo motor, which is the object of measurement OB1, and output information related to the measurement result. According to the present invention, the optical encoder 1 is not limited to a rotary encoder, but can also be a linear encoder configured to measure linear movement.

[0031] Specifically, such as Figure 1 As shown in Figure A, the optical encoder 1 includes a light source 2, a reflector 3, and a light-receiving unit 4. The reflector 3 has multiple reflective regions 30, which include multiple M-code regions R1 arranged in a row according to a specific bit pattern representing an M-code. The "M-code (M-sequence code)" used herein consists of 2 bits per cycle. n The code consists of n bits of information (where "n" is a natural number and each bit represents either "0" or "1"). In the code, the n bits of information (each a "0" or "1") starting from any point in the code are unique. Throughout the entire circumference of the code, there are no repeating "2" bits. n "Information. The reflector 3 is configured to move together with the movement of the object (measurement object OB1), and is configured to pass through one or more regions (detection region X1; reference) of multiple M-code regions R1 corresponding to n bits." Figure 2 The light from light source 2 is reflected. For example, in the case of 4 bits, the "M code" has 2 unique characters that do not repeat each other throughout the entire circumference. 4The information is transmitted through the reflector 3, which reflects the light from the light source 2 through the detection area X1 corresponding to the 4 bits. In short, as an example, the optical encoder 1 is a reflective optical absolute encoder based on the M-sequence.

[0032] The light-receiving unit 4 is configured to receive reflected light C2 from the reflective unit 3. The light-receiving unit 4 is configured to receive the reflected light C2 for photoelectric conversion. Multiple M-code regions R1 have: a first surface 31 corresponding to a first code information B1, which is one of the bits of information in the M-code; and a second surface 32 corresponding to a second code information B2, which is another bit of information in the M-code. The second surface 32 has a tilt structure D1 that is different from the tilt structure of the first surface 31. In this embodiment, the first code information B1 is a "0" of a bit information (0, 1), and the second code information B2 is a "1" of a bit information (0, 1). As used herein, the feature "the tilt structure D1 of the first surface 31 and the tilt structure D1 of the second surface 32 are different from each other" means that they have surfaces with tilt angles different from each other relative to a reference plane (e.g., including the front surface of the rotating plate 5). Figure 1 In example A, the first face 31 corresponding to information “0” has a smaller tilt angle than the second face 32 corresponding to information “1”.

[0033] like Figure 2 As shown, the light-receiving section 4 has a first light-receiving group 41 and a second light-receiving group 42. The first light-receiving group 41 includes a plurality of first light-receiving elements 401 arranged along one direction (column direction A1) to receive reflected light C2 reflected from the first surface 31. The second light-receiving group 42 is arranged on a side farther from the reflective section 3 than the first light-receiving group 41. The second light-receiving group 42 includes a plurality of second light-receiving elements 402 arranged along the column direction A1 to receive reflected light C2 reflected from the second surface 32. The first light-receiving group 401 and the second light-receiving group 42 are arranged such that the positions of the first light-receiving elements 401 and the second light-receiving elements 402 are staggered from each other in the column direction A1.

[0034] According to this configuration, the reflective section 3 has multiple reflective regions 30 including multiple M-code regions R1 arranged in a column, and the first light-receiving element 401 and the second light-receiving element 402, which receive the reflected light C2, are staggered from each other in one direction (column direction A1). Therefore, the optical encoder 1 has a structure for chattering countermeasures: providing light-receiving signals that are phase-shifted relative to each other, for example by half a phase, so that any one of these signals can be detected, thereby reducing the possibility that chattering makes it difficult to determine whether the information is "0" or "1". In addition, the optical encoder 1 can help increase the amount of light received in the light-receiving section 4 (approximately double). Specifically, compared to the case where multiple M-code regions R1 are provided in each of the two columns as a countermeasure against phase shift, the amount of light received in the light-receiving section 4 can be increased. Therefore, the insufficient amount of light received in the light-receiving section 4 can be improved.

[0035] According to the present invention, the optical encoder 1 is not limited to the configuration of representing the M code in a "specific positioning mode". According to another aspect of this embodiment, the optical encoder 1 includes a light source 2, a reflector 3, and a light-receiving unit 4. The reflector 3 has a plurality of reflective regions 30, which include a plurality of code regions R0 arranged in a row according to a specific positioning mode. The reflector 3 is configured to move together with the movement of the object (measurement object OB1) and is configured to reflect light from the light source 2 through one or more regions (detection regions X1) corresponding to n bits in the plurality of code regions R0, where "n" is a natural number. The light-receiving unit 4 is configured to receive the reflected light C2 from the reflector 3 for photoelectric conversion. The reflector 3 includes three or more types of reflective regions 30 having different tilt structures D1. The light-receiving unit 4 has three or more light-receiving groups 40 corresponding to and receiving light from the three or more types of reflective regions 30 respectively. According to this configuration, the reflective section 3 has multiple reflective regions 30 including multiple code regions R0 arranged in a column, and the light-receiving section 4 has three or more light-receiving groups 40 that correspond to and receive light from the three or more types of reflective regions 30 respectively. As a result, compared with the case where multiple code regions R0 are provided in each of multiple columns, the amount of light received in the light-receiving section 4 can be increased. Therefore, the insufficient amount of light received in the light-receiving section 4 can be improved.

[0036] (2) Details

[0037] Next, refer to Figure 1 A to Figure 3 The details of the optical encoder 1 according to this embodiment will now be explained.

[0038] (2.1) Overall Configuration

[0039] like Figure 1As shown in A, the optical encoder 1 according to this embodiment includes a light source 2, a reflector 3, a light receiver 4, a rotating plate 5, a substrate 6, and a processor 7.

[0040] Figure 1 Figure A is a schematic diagram illustrating the overall structure of the optical encoder 1. The light source 2, light-receiving unit 4, rotating plate 5, substrate 6 (printed substrate), processor 7, and any other components can be accommodated within... Figure 1 The housing shown in the diagram is omitted in A, or it is held by the housing. Figure 1 In A, the rotating plate 5 is enlarged and only a portion of it is shown. Figure 1 In example A, only the light-receiving part 4 of the light source 2, processor 7, and light-receiving part 4 is disposed on the substrate 6. In an alternative example, the light source 2 or processor 7, etc., may be disposed on the same substrate 6.

[0041] Light source 2 is a diffuse light source or a point light source with a relatively small emitting surface. Light source 2 includes a light-emitting diode (LED) or a laser diode. Light source 2 may also include a collimating lens. Light source 2 is arranged to face a surface 50 of the rotating plate 5 where the reflector 3 is arranged, and is configured to emit light (emitted light C1) toward the reflector 3. Light source 2 can be mounted on substrate 6, or on a substrate different from substrate 6.

[0042] The rotating plate 5 has a surface 50 on which the reflective part 3 is provided. Figure 1 The rotating plate 5 is a component (the upper surface of A). For example, the rotating plate 5 can be a component with a circular or annular toroidal shape, and can be made by resin molding. The optical encoder 1 is a rotary encoder as described above, and the rotating plate 5 is attached to the rotating shaft (measured object OB1) of a servo motor or the like. The rotating plate 5 is configured to move (rotate) together with the movement (rotation) of the measured object OB1.

[0043] The reflector 3 is a component configured to reflect the emitted light C1 from the light source 2. The reflector 3 is mounted on a rotating plate 5 that rotates together with the measuring object OB1. The reflector 3 has an annular shape when viewed along the axial direction of the rotating plate 5. The central axis of the reflector 3 is approximately aligned with the central axis of the rotating plate 5. The reflector 3 includes a resin layer and a metal film. The resin layer may be formed from a portion of the rotating plate 5. The metal film is arranged to face the light source 2 to reflect the emitted light C1. The material of the metal film is not limited, as long as it can reflect the emitted light C1. The metal film can be formed on the resin layer by deposition or sputtering of gold, silver, aluminum, or chromium.

[0044] For example, the reflective portion 3 can be formed along the circumferential direction on the entire circumferential surface of the rotating plate 5. The reflective portion 3 is configured such that the absolute angular position of the rotating axis (measuring object OB1) during one rotation is identifiable. In this embodiment, the reflective portion 3 has a plurality of reflective regions 30, which include a plurality of code regions R0 arranged in a row according to a specific positioning pattern. As described above, in this embodiment, in the example, the "specific positioning pattern" represents the M code, and the code region R0 includes the M code region R1. The plurality of reflective regions 30 are arranged in a row in such a way that a circle is drawn around the central axis of the rotating plate 5.

[0045] The reflector 3 is arranged to reflect the emitted light C1 from the light source 2 through the detection area X1 corresponding to at least n bits in one of the multiple code areas R0 (M code area R1). That is, the optical encoder 1 is configured such that the emitted light C1 from the light source 2 illuminates at least the detection area X1. Figure 2 This shows an example of the detection region X1 corresponding to 4 bits. Figure 2 In the example, there are seven reflection regions 30 in the detection region X1, and four of these seven reflection regions 30 correspond to the M code region R1.

[0046] Multiple M-code regions R1 each have: multiple first surfaces 31 corresponding to the first code information B1 (in this embodiment, a "0" of a bit information (0, 1)); and multiple second surfaces 32 corresponding to the second code information B2 (in this embodiment, a "1" of a bit information (0, 1)). Figure 2 In the example shown, the rotating plate 5 is positioned such that the first surface 31, the second surface 32, and the first surface 31, corresponding to the 4-bit information "0, 1, 1, 0", enter the detection area X1. Therefore, in response to the emitted light C1 reflected by the M-code area R1, the light-receiving unit 4 outputs a signal corresponding to the digital information "0, 1, 1, 0", and the processor 7 calculates the absolute angular position (such as "45 degrees" or any other degree) corresponding to the digital information "0, 1, 1, 0".

[0047] Each first surface 31 is an inclined surface. For example, the first surface 31 is inclined relative to a virtual plane (hereinafter referred to as the "reference plane") that is perpendicular to the central axis of the rotation axis (the object being measured OB1). In this embodiment, as an example, the reference plane is substantially parallel to a flat surface 50 of the rotating plate 5, and the first surface 31 is inclined relative to a surface 50.

[0048] To facilitate understanding of the correspondence between a single bit of information (0, 1) and the reflection area 30, Figure 2The black block indicating the first code information B1 “0” and the white block indicating the second code information B2 “1” are shown, but they are non-physical components and do not exist.

[0049] Each second surface 32 is an inclined surface. The second surface 32 is inclined relative to a reference plane, and thus inclined relative to a surface 50. The second surface 32 has an inclined structure D1 different from the inclined structure of the first surface 31. In this embodiment, the second surface 32 has an inclined structure D1 with an inclination angle relative to the reference plane that is different from the inclination angle of the first surface 31. As an example, in this embodiment, the inclination angles θ1 and θ2 are set to satisfy the relationship "0 < θ1 < θ2", where θ1 represents the inclination angle of the first surface 31 relative to the reference plane and θ2 represents the inclination angle of the second surface 32 relative to the reference plane. In an alternative example, the inclination angles θ1 and θ2 may be set to satisfy the relationship "0 < θ2 < θ1".

[0050] In this embodiment, each of the plurality of reflective regions 30 has a radial direction A2 (reference) of the reflective portion 3. Figure 1 The outer edge E1 and inner edge E2 on A). In this embodiment, depending on the positional relationship between the light source 2 and the light-receiving part 4, the first surface 31 and the second surface 32 are each tilted, such that the outer edge E1 rises higher in the radial direction A2 relative to the inner edge E2. Specifically, when viewed along the axial direction of the rotating plate 5, the light source 2 and the light-receiving part 4 are arranged along the radial direction A2. The light source 2 is arranged on the outer side of the light-receiving part 4 in the radial direction A2. (One or more) the first surface 31 and (one or more) the second surface 32 are each tilted on the outer side in the radial direction A2 in a manner that is closer to the light-receiving part 4 (farther from one surface 50 of the rotating plate 5) than the center of the reflector 3, such that the emitted light C1 of the light source 2 reflected by the reflector 3 travels toward the light-receiving part 4.

[0051] In this embodiment, for the first surface 31 and the second surface 32, the outer edges E1 of the plurality of reflective regions 30 are at the same height relative to one surface 50 of the rotating plate 5 (see reference). Figure 1 (A). On the other hand, for the first surface 31 and the second surface 32, the inner edges E2 of the plurality of reflective regions 30 are at different heights relative to one surface 50 of the rotating plate 5 (see reference). Figure 1 (A) The inner edge E2 of the first face 31 is located above the inner edge E2 of the second face 32, such that the tilt angles θ1 and θ2 satisfy the relationship "0 < θ1 < θ2".

[0052] Note that in Figure 2 In the figure, the different tilt angles of the multiple reflective regions 30 of the reflective part 3 are shown by points of different concentrations. In this figure, reflective regions 30 with points of the same concentration have the same tilt angle.

[0053] The multiple reflection regions 30 also include multiple incremental regions R2. As an example, in this embodiment, the multiple incremental regions R2 are periodically arranged at predetermined intervals in the same column as the multiple M-code regions M1. The multiple incremental regions R2 correspond to incremental tracks. That is, as an example, the optical encoder 1 is an encoder that includes both absolute tracks and incremental tracks, and has a specific structure in which these tracks are implemented in a column. Note that the incremental regions R2 are provided to obtain signals based on an incremental method for measuring relative position changes. In response to the emitted light C1 being reflected by the incremental regions R2, the output signal on the light-receiving section 4 becomes ON. According to the rotation of the rotating plate 5, this output signal repeatedly changes between ON and OFF to form a pulse signal (analog signal).

[0054] In this embodiment, as an example, the M-code region R1 and the incremental region R2 are arranged alternately. That is, an incremental region R2 is inserted between two adjacent M-code regions R1. Figure 2 In the example, the detection region X1 corresponding to 4 bits includes four M-code regions R1 and three incremental regions R2. Note that when rotating plate 5 from... Figure 2 When the state shown is rotated at an angle corresponding to a reflection area 30, the three M-code areas R1 and the four incremental areas R2 will be included in the detection area X1.

[0055] Multiple incremental regions R2 have surfaces (hereinafter referred to as "(one or more) third surfaces 33"), each of which has an inclined structure D1 that is different from any inclined structure of (one or more) first surfaces 31 and (one or more) second surfaces 32. In other words, the reflective part 3 of this embodiment includes three types of reflective regions 30 having inclined structures D1 that are different from each other.

[0056] In this embodiment, as an example, each third surface 33 is approximately parallel to the reference plane, and thus approximately parallel to a surface 50. Therefore, the tilt angle satisfies the relationship "θ3≈0<θ1<θ2", where θ3 represents the tilt angle of the third surface 33 relative to the reference plane. Note that the relationship "θ3>0" can also be satisfied. The satisfaction of the tilt angle relationship "θ3<θ1<θ2" depends on the positional relationship between the first light-receiving group 41, the second light-receiving group 42, and the third light-receiving group 43 of the light-receiving section 4, as described later. However, satisfying the above relationship may only be an example, and is not limited to it.

[0057] The light-receiving unit 4 is configured to receive reflected light C2 from the reflector 3. That is, the light-receiving unit 4 is configured to receive the reflected light C2 and perform photoelectric conversion on it. The light-receiving unit 4 has a plurality of light-receiving elements 400. For example, the plurality of light-receiving elements 400 can be photodiodes. For example, the light-receiving unit 4 can be implemented as a photodiode array. The light-receiving unit 4 can be implemented as an image sensor. The light-receiving unit 4 is mounted on a substrate 6 (printed substrate) such that the light-receiving surfaces of each light-receiving element 400 face the reflector 3. The light-receiving unit 4 is electrically connected to a processor 7 and is configured to output to the processor 7 an electrical signal (which may be referred to as a "light-receiving signal"; for example, a voltage signal) corresponding to the amount of reflected light C2 received by each light-receiving element 400.

[0058] like Figure 2 As shown, the light-receiving unit 4 has a first light-receiving group 41, a second light-receiving group 42, and a third light-receiving group 43. Figure 1 In example A, the light-receiving part 4 is arranged on the back side (lower surface) of the substrate 6 facing the reflective part 3. Figure 2 From Figure 1 The diagram shows the light-receiving portion 4 as seen from the upper side of the substrate 6 shown in Figure A, with the substrate 6 omitted.

[0059] The first light-receiving group 41, the second light-receiving group 42, and the third light-receiving group 43 are arranged, for example, from the outside to the inside in the radial direction A2, in the order of the third light-receiving group 43, the first light-receiving group 41, and the second light-receiving group 42.

[0060] The first light-receiving group 41 includes a plurality of first light-receiving elements 401 (light-receiving elements 400) arranged along one direction (column direction A1) to receive reflected light C2 reflected from the first surface 31. The column direction A1 used herein may, for example, be a direction perpendicular to a straight line that, when viewed along the axial direction of the rotating plate 5, passes through the detection area X1 and is parallel to the radial direction A2. Figure 2 In the example, based on the number of reflective regions 30 included within the detection region X1 (i.e., seven), the first light-receiving group 41 includes seven first light-receiving elements 401 arranged in a column along the column direction A1. For ease of understanding, in Figure 2 In the middle, the area illuminated by the reflected light C2 from the first surface 31 (the first illuminated area Op1) should be shaded with diagonal lines. Figure 2 In the example, two first illumination regions Op1 exist in the first light-receiving group 41, corresponding to the positions of the two M code regions R1 (first surface 31) representing the first code information B1 “0” in the seven reflection regions 30 included in the detection region X1.

[0061] The second light-receiving group 42 is arranged on a side farther from the reflector 3 than the first light-receiving group 41. The second light-receiving group 42 includes a plurality of second light-receiving elements 402 (light-receiving elements 400) arranged along the column direction A1 to receive reflected light C2 reflected from the second surface 32. Note that a common design portion can be used for the second light-receiving elements 402 and the first light-receiving elements 401, and their light-receiving surfaces can have the same shape and size.

[0062] Similar to the first light-receiving group 41, the second light-receiving group 42 includes seven second light-receiving elements 402 arranged in a row along the column direction A1, depending on the number of reflective areas 30 included in the detection area X1 (i.e., seven). For ease of understanding, in Figure 2 In the middle, the area illuminated by the reflected light C2 from the second surface 32 (the second illuminated area Op2) should be shaded with a diagonal line. Figure 2 In the example, there are two second illumination areas Op2 in the second light-receiving group 42, corresponding to the positions of the two M code areas R1 (second surface 32) representing the second code information B2 “1” in the seven reflection areas 30 included in the detection area X1.

[0063] In this embodiment, the first light-receiving group 41 and the second light-receiving group 42 are arranged such that the positions of the first light-receiving element 401 and the second light-receiving element 402 are offset from each other in the column direction A1. This "offset" is, for example, taken into account a "phase shift," which may be generated by jitter noise in the light-receiving signal and may be a phase shift corresponding to half a phase (90 degrees). In this embodiment, in the column direction A1, the position of the second light-receiving group 42 is offset relative to the position of the first light-receiving group 41 by half the size of a light-receiving element 400.

[0064] According to the optical encoder 1 of this embodiment, in a normal state where there is no "phase shift" caused by jitter noise, the processor 7 reads out digital information based on the light-receiving signals obtained from the seven first light-receiving elements 401 of the first light-receiving group 41. Figure 2 In the example, processor 7 determines that the first irradiated area Op1 is "0" (skipping one area), and the non-irradiated area is "1", and as a result, reads the digital information "0, 1, 1, 0".

[0065] On the other hand, in cases where a "phase shift" occurs due to jitter noise and digital information cannot be read from the light-receiving signal obtained from the first light-receiving group 41, digital information is read from the light-receiving signal obtained from the seven second light-receiving elements 402 of the second light-receiving group 42. Figure 2In the example, since no "phase shift" occurs, each second illumination region Op2 is located across the corresponding two second light-receiving elements 402. If a "phase shift" occurs, the processor 7 reads the digital information "0, 1, 1, 0" based on the position of the second illumination region Op2 in the second light-receiving group 42.

[0066] The third light-receiving group 43 includes a plurality of third light-receiving elements 403 (light-receiving elements 400) arranged along the column direction A1 to receive reflected light C2 reflected from the surfaces (third surfaces 33) of the plurality of incremental regions R2. For example, each third light-receiving element 403 may be an element having a light-receiving surface with a shape and size different from that of the light-receiving surfaces of the first light-receiving element 401 and the second light-receiving element 402. Figure 2 In the example, the dimension of each third light-receiving element 403 in the column direction A1 is the same as that of the first light-receiving element 401 and the second light-receiving element 402, while its dimension in the radial direction A2 is approximately half of that of the first light-receiving element 401 and the second light-receiving element 402.

[0067] Furthermore, the third light-receiving group 43 has two columns, each column including seven third light-receiving elements 403 (i.e., a total of fourteen third light-receiving elements 403). Specifically, the third light-receiving group 43 includes a first column 43A and a second column 43B, and each of the first column 43A and the second column 43B has seven third light-receiving elements 403 arranged along the column direction A1. The first column 43A and the second column 43B are arranged at positions offset from each other by half the size of a third light-receiving element 403 in the column direction A1 to obtain analog signals of two phases (phase A and phase B) that are 90 degrees out of phase with each other. The first column 43A is used to obtain the A-phase (sin phase) analog signal, and the second column 43B is used to obtain the B-phase (cos phase) analog signal. The processor 7 obtains the two-phase (A-phase and B-phase) analog signals and calculates the rotational speed and rotational direction of the object OB1 being measured.

[0068] For ease of understanding, Figure 2 In the middle, the area illuminated by the reflected light C2 from the third surface 33 (the third illuminated area Op3) should be shaded with a diagonal line. Figure 2 In the example, there are three third illumination regions Op3 in the third light-receiving group 43, corresponding to the positions of the three incremental regions R2 (third surface 33) among the seven reflection regions 30 included in the detection region X1. Figure 2 In the example, in the first column 43A, each third illumination region Op3 is partially fitted to a corresponding single third light-receiving element 403, while in the second column 43B, each third illumination region Op3 is partially fitted (across) two corresponding third light-receiving elements 403.

[0069] In this embodiment, as an example, the third light-receiving group 43 is arranged on the side closer to the reflective portion 3 than the first light-receiving group 41 and the second light-receiving group 42. In an alternative example, the third light-receiving group 43 may be arranged on the side farther from the reflective portion 3 than the first light-receiving group 41 and the second light-receiving group 42. Further alternatively, the third light-receiving group 43 may be arranged in a split manner on both the side closer to the reflective portion 3 and the side farther from the reflective portion 3.

[0070] Processor 7 (signal processor) can be implemented as a computer system comprising one or more processors (microprocessors) and one or more memories. That is, the computer system performs the function of processor 7 by having one or more processors execute one or more programs (applications) stored in one or more memories. In this embodiment, the program is pre-stored in one or more memories of processor 7. However, this is merely an example and should not be construed as limiting. The program may also be downloaded via telecommunications lines such as the Internet, or distributed after being stored on a storage medium such as a memory card.

[0071] The processor 7 is electrically connected to the light-receiving unit 4. The processor 7 has functions for signal processing and calculation related to the electrical signals (light-receiving signals) output from the light-receiving unit 4. Specifically, for example, the processor 7 amplifies and digitally processes the light-receiving signals output from the first light-receiving group 41 (or the second light-receiving group 42) to calculate the absolute angular position of the rotating shaft (the object being measured OB1) during one rotation. Furthermore, the processor 7 amplifies and digitally processes the light-receiving signals output from the third light-receiving group 43 to calculate the rotational speed and direction of the rotating shaft (the object being measured OB1). The processor 7 outputs the calculation results to an external device (such as a control device for controlling a motor).

[0072] As described above, under normal conditions, the processor 7 performs calculations for the absolute angular position based on the light received signal obtained from the first light-receiving group 41. In the case of a "phase shift" caused by jitter noise, the processor 7 determines, for example, which light received signal should be used, from the first light-receiving group 41 or the second light-receiving group 42, based on an analog signal, and then performs calculations for the absolute angular position based on the determined light received signal.

[0073] Furthermore, the processor 7 has a function to detect "errors" caused by light being reflected or blocked by foreign objects that may enter the optical encoder 1. In this embodiment, the processor 7 monitors whether a break in the reciprocal relationship has occurred based on the light-receiving signals obtained from the first light-receiving group 41 and the second light-receiving group 42. Specifically, in the normal state where there are no foreign objects, the positions of the first irradiation area Op1 in the first light-receiving group 41 and the second irradiation area Op2 in the second light-receiving group 42 are as follows: Figure 2 The reciprocal relationship is illustrated. Conversely, if, for example, the emitted light C1 traveling towards the first surface 31 or the reflected light C2 reflected from the first surface 31 is blocked by a foreign object, and the first irradiation area Op1 is absent in the first light-receiving group 41 while a second irradiation area Op2 normally exists in the second light-receiving group 42, then the reciprocal relationship is broken. Furthermore, if the light is reflected by a foreign object, and an additional first irradiation area Op1 exists in the first light-receiving group 41 while a second irradiation area Op2 normally exists in the second light-receiving group 42, then the reciprocal relationship is broken. When a break in the reciprocal relationship is detected, the processor 7 determines that an "error" caused by a foreign object exists. The processor 7 outputs the determination result to an external source (such as a control device that controls a motor).

[0074] (2.2) Manufacturing method

[0075] The following will be referenced Figure 3 This describes a method for manufacturing a reflective part 3 with an inclined structure D1 in an optical encoder 1.

[0076] The reflective portion 3 having a tilted structure D1 can be manufactured using nanoimprint lithography. For example, a resist Y1 made of a UV-curable resin or the like is applied to a substrate Y2. Then, a mold 8 (metal mold) equipped with nanoscale micro-tilted structures is imprinted onto the resist Y1 from above, applying pressure to the resist Y1. Subsequently, the resist Y1 is irradiated with UV light and cured. The mold 8 is then removed, and a metal film is formed by depositing gold, silver, aluminum, or chromium on the surface of the resist Y1 with the micro-tilted structures. As a result, a reflective portion 3 comprising a first surface 31, a second surface 32, and a third surface 33 having tilted structures D1 that are different from each other is manufactured. Note that... Figure 3 This is a schematic front view of the reflector 3 as seen along the radial direction A2.

[0077] (advantage)

[0078] Reference Figure 4The advantages of the optical encoder 1 according to this embodiment will be explained. According to the optical encoder 1, as described above, the reflective portion 3 has multiple reflective regions 30 including multiple M-code regions R1 arranged in a column. Furthermore, the positions of the multiple first light-receiving elements 401 and the multiple second light-receiving elements 402 that receive the reflected light C2 are staggered relative to each other in the column direction A1. For example, this allows the optical encoder 1 to have a structure that serves as a countermeasure against phase shifts in the light-receiving signal that may be caused by jitter noise. Furthermore, the optical encoder 1 can help increase the amount of light received in the light-receiving portion 4.

[0079] Figure 4 The main part of the optical encoder 1X of the comparative example is shown, and more specifically, an enlarged view of a portion of the reflective part 3X of the optical encoder 1X having multiple M-code regions R1X arranged in "two columns" is shown. Between the two columns of M-code regions R1X, the incremental region R2X is arranged separately from the M-code regions R1X. In the comparative example, the two columns of M-code regions R1X are arranged at positions that are offset from each other by half a phase. Therefore, the optical encoder 1X of the comparative example also has a structure used as a countermeasure against phase shifts that may be caused by jitter noise.

[0080] Assuming that in the optical encoder 1 according to this embodiment, each reflective region 30 arranged in a row is configured to have a similar characteristic to... Figure 4 The longitudinal length W1 shown is approximately the same as the longitudinal length (length along the radial direction A2). It is further assumed that the light illumination areas on the reflective portions 3 and 3X of the optical encoders 1 and 1X are the same. In this case, the amount of light received by each light-receiving element 400 of the optical encoder 1 is generally greater than that of each light-receiving element of the optical encoder 1X.

[0081] Specifically, in the optical encoder 1 according to this embodiment, an incremental region R2 is inserted into the M-code regions R1 arranged in a row. Although this structure may make the width of each reflective region 30 smaller than the width of the optical encoder 1X, this structure can increase the amount of light received in the light-receiving portion 4 of the M-code region R1 to approximately twice the amount of light received by the optical encoder 1X.

[0082] Generally, reflective optical encoders are easier to make thinner overall than transmissive optical encoders. However, since the reflective part must be arranged in a limited area of ​​the rotating plate, reflective optical encoders may suffer from insufficient light reception in the light-receiving part. In this regard, the structure of the optical encoder 1 according to this embodiment can help increase the amount of light received in the light-receiving part 4. Furthermore, the increase in the amount of light received in the light-receiving part 4 can help improve the resolution.

[0083] In the optical encoder 1, the plurality of reflective regions 30 also include a plurality of incremental regions R2 arranged periodically in a column at predetermined intervals. Compared to a structure in which the incremental regions are arranged in a different column than the plurality of M-code regions R1 (such as the structure of the optical encoder 1X in the comparative example), this helps to increase the amount of light received in the light-receiving section 4. The structure of the optical encoder 1 can increase the amount of light received in the light-receiving section 4 with respect to the incremental regions R2 to approximately twice the amount of light received by the optical encoder 1X.

[0084] Furthermore, the third surface 33 of each of the multiple incremental regions R2 has a tilt structure D1 that differs from any tilt structure in the first surface 31 and the second surface 32. This increases the possibility of accurately distinguishing analog signals (first code information B1 and second code information B2) based on the incremental method.

[0085] In the optical encoder 1 according to this embodiment, the reflective portion 3 has multiple reflective regions 30, each including multiple code regions R0 arranged in a column. The light-receiving portion 4 has three light-receiving groups 40 that correspond to and receive light from the three types of reflective regions 30 respectively. Compared to the case where multiple code regions are provided in multiple columns (for example, referring to the optical encoder 1X of the comparative example), this helps to increase the amount of light received in the light-receiving portion 4. This helps to improve the insufficient amount of light received in the light-receiving portion 4.

[0086] (3) Variations

[0087] The above embodiments are merely one of many embodiments of the present invention, and can be easily modified, altered, replaced, or combined with any other embodiments based on design choices or any other factors without departing from the true spirit and scope of the invention. Variations of the above embodiments will be listed one by one. In the following description, the optical encoder 1 of the above embodiments will sometimes be referred to as the "basic example". Note that any variations described below can be combined with the basic example and / or other variations.

[0088] In the following description, the same reference numerals are used to describe components that are substantially the same as those in the basic example, and their descriptions may be omitted as appropriate.

[0089] (3.1) First variation

[0090] refer to Figure 5 The first variation will be illustrated using A through C. Note that, for ease of explanation, ... Figure 5 In sections A to C, the incremental region R2 (third face 33) is not shown.

[0091] For the purpose of comparison, Figure 5Figure A schematically illustrates a basic example of a reflective portion 3 comprising one or more first surfaces 31 and one or more second surfaces 32 having different tilting structures D1 from each other. Each first surface 31 has a first reflective structure 301 with a tilt angle relative to a reference plane set to "θ1". Each second surface 32 has a second reflective structure 302 with a tilt angle relative to the reference plane set to "θ2". In the basic example, the tilt angles satisfy the relationship "0 < θ1 < θ2". Furthermore, the first surface 31 and the second surface 32 are tilted (upward) in a manner that their outer sides in the radial direction A2 are closer to the light-receiving portion 4 than their centers.

[0092] Alternatively, (one or more) first face 31 and (one or more) second face 32 may have, as Figure 5 The tilted structures D1 shown in B are different from each other. Figure 5 B schematically illustrates the first surface 31 and the second surface 32 (one or more) of the reflective portion 3A according to this modified example, each having a different inclined structure D1. Figure 5 In example B, similar to the basic example, each second surface 32 has a second reflective structure 302 with an inclination angle relative to the reference plane set to "θ2". On the other hand, each first surface 31 has a third reflective structure 303 with an inclination angle relative to the reference plane set to "θ1A".

[0093] In the reflective portion 3A of this modified example, the tilt angle also satisfies the relationship "0 < θ1A < θ2". However, the first surface 31 and the second surface 32 have different tilt directions from each other. Each first surface 31 tilts downwards in a manner that its outer side in the radial direction A2 is farther from the center of the reflective portion 3A than the light-receiving portion 4. The height of the inner edge E2 of each first surface 31 in this modified example relative to a surface 50 of the rotating plate 5 is greater than that in the basic example. Note that "θ1A" can be approximately 0 degrees. In this case, the tilt angle θ3 of each third surface 33 can preferably be set to an angle other than 0 degrees. According to the reflective portion 3A of this modified example, compared with the reflective portion of the basic example, the first light-receiving group 41 of the light-receiving portion 4 can be located at the outer side in the radial direction A2.

[0094] then, Figure 5 C schematically illustrates another example (reflector 3B) according to this modification, with one or more first surfaces 31 and one or more second surfaces 32 having different inclined structures D1 from each other. Figure 5In example C, similar to the basic example, each second surface 32 has a second reflective structure 302 with an inclination angle relative to the reference plane set to "θ2". On the other hand, each first surface 31 has a fourth reflective structure 304 with an inclination angle relative to the reference plane set to "θ1B".

[0095] In the reflective portion 3B, the tilt angles also satisfy the relationship "0 < θ1B < θ2". However, the first surface 31 and the second surface 32 have different tilt directions. Each first surface 31 tilts downwards in a manner that is further away from the light-receiving portion 4 in the radial direction A2 than at the center of the reflective portion 3B. Furthermore, the outer edge E1 of the first surface 31 is located at a lower position than the outer edge E1 of the second surface 32, while the inner edge E2 of the first surface 31 and the inner edge E2 of the second surface 32 are aligned, which is different from the basic example. Note that "θ1B" can be approximately 0 degrees. In this case, the tilt angle θ3 of each third surface 33 can preferably be set to an angle other than 0 degrees. According to the reflective portion 3B of this modified example, compared with the basic example, the first light-receiving group 41 of the light-receiving portion 4 can be located at a position on the outer side in the radial direction A2.

[0096] (3.2) Second variation

[0097] refer to Figure 6 Let's illustrate the second variation.

[0098] Figure 6 The reflective portion 3C and the light-receiving portion 4C of this modified example are schematically shown. The reflective portion 3C has multiple reflective regions 30 including multiple M-code regions R1 and incremental regions R2 arranged in a row. The light-receiving portion 4C has three light-receiving groups 40 (first light-receiving group 41 to third light-receiving group 43) that correspond to the first surface 31 to the third surface 33 of the reflective portion 3C and receive light from these first surface 31 to the third surface 33 respectively (that is, as in the basic example, a three-level (grayscale) scheme of three light-receiving groups 40 is used). Figure 6 In the figure, the different tilt angles of multiple reflective regions 30 are shown by points of different concentrations. In this figure, reflective regions 30 with points of the same concentration have the same tilt angle.

[0099] The difference between this variant and the basic example is that the incremental region R2 of the reflector 3C is periodically arranged such that the incremental region R2 is arranged between every two M-code regions R1 (in the basic example, each M-code region R1). Note that, as an example, Figure 6 An example of the detection region X1 corresponding to 5 bits is shown. Figure 6 In the example, there are seven reflection regions 30 in the detection region X1, and five of these seven reflection regions 30 correspond to the M-code region R1. Figure 6In the example, the light-receiving unit 4C outputs a signal representing the information "0, 0, 1, 1, 0".

[0100] The difference between this modified example and the basic example is that, in the light-receiving section 4C, there is no positional misalignment in the column direction A1 between the first light-receiving group 41 and the second light-receiving group 42. That is, the optical encoder 1 of this modified example does not have a structure to counteract phase shifts that may be caused by jitter noise. Note that, since the first surface 31 and the second surface 32 have different tilt structures D1 and the light-receiving section 4C has the first light-receiving group 41 and the second light-receiving group 42, this modified example, like the basic example, can also detect "errors" caused by light reflection or light obstruction due to foreign objects.

[0101] Furthermore, in this modified example, the third light-receiving group 43 of the light-receiving section 4C is arranged in only one column, which is a further difference from the basic example with a first column 43A and a second column 43B to obtain a two-phase analog signal.

[0102] A further difference between this modified example and the basic example is that, in the light-receiving part 4C, the third light-receiving group 43 is arranged on the side farther from the reflective part 3 than the first light-receiving group 41 and the second light-receiving group 42. According to this modified example, for example, the reflective part 3C can be configured such that the tilt angles of the first surface 31 to the third surface 33 relative to the reference plane can satisfy the relationship "θ1<θ2<θ3".

[0103] Compared to the case where multiple code regions are set in each of multiple columns (for example, see the optical encoder 1X of the comparative example), this modification can also help increase the amount of light received in the light-receiving section 4C. This can help improve insufficient light received in the light-receiving section 4C.

[0104] (3.3) Third variation

[0105] refer to Figure 7 Let's illustrate the third variation.

[0106] Figure 7 The reflective portion 3D and the light-receiving portion 4D of this modified example are schematically shown. The reflective portion 3D has multiple reflective regions 30, including multiple M-code regions R1 and incremental regions R2 arranged in a row. This modified example differs from the basic example in that the reflective portion 3D includes two types of third surfaces 33 (third surface 33A and third surface 33B). Figure 7 In the figure, the different tilt angles of multiple reflective regions 30 are shown by points of different concentrations. In this figure, reflective regions 30 with points of the same concentration have the same tilt angle.

[0107] The light-receiving part 4D has four light-receiving groups 40 (four (grayscale) scheme) that correspond to and receive light from the (one or more) first surface 31, (one or more) second surface 32, third surface 33A and third surface 33B of the reflective part 3D respectively.

[0108] Except for the third surfaces 33A and 33B, the reflective portion 3D of this modified example is substantially the same as the reflective portion of the second modified example. Therefore, the description of the substantially identical structure is omitted. The third surfaces 33A and 33B have different tilting structures D1. For example, the reflective portion 3D is configured such that the tilt angles satisfy the relationship "θ3A<θ1<θ2<θ3B", where "θ3A" represents the tilt angle of the third surface 33A relative to the reference plane, and "θ3B" represents the tilt angle of the third surface 33B relative to the reference plane.

[0109] In this modified example, the light-receiving portion 4D has a first light-receiving group 41, a second light-receiving group 42, and two third light-receiving groups 43 (43C, 43D). The two third light-receiving groups 43C and 43D are respectively arranged on a side closer to the reflective portion 3D than the first light-receiving group 41 and the second light-receiving group 42, and on a side farther from the reflective portion 3D than the first light-receiving group 41 and the second light-receiving group 42. The reflected light C2 reflected from the third surface 33A is received by the third light-receiving group 43C. The reflected light C2 reflected from the third surface 33B is received by the third light-receiving group 43D.

[0110] The third light-receiving group 43C is a light-receiving group provided for "even numbers on both sides". For example, if the sum of the code information of the M-code regions R1 existing on both sides of the incremental region R2 is even, then the third surface 33A is set for that incremental region R2. The third light-receiving group 43C is a light-receiving group for receiving reflected light C2 from the third surface 33A set in this way. Figure 7 In the example, regarding the upper incremental region R2, the code information on both sides of the upper incremental region R2 is "0, 0", so their sum is 0 (=0+0) (even number). Therefore, a third surface 33A is set for the upper incremental region R2.

[0111] On the other hand, the third light-receiving group 43D is a light-receiving group provided for "odd numbers on both sides". For example, if the sum of the code information of the M-code regions R1 existing on both sides of the incremental region R2 is odd, then the third surface 33B is set for that incremental region R2. The third light-receiving group 43D is a light-receiving group for receiving reflected light C2 from the third surface 33B set in this way. Figure 7 In the example, regarding the lower incremental region R2, the code information on both sides of the lower incremental region R2 is "1, 0", so their sum is 1 (=1+0) (odd number). Therefore, a third face 33B is set for the lower incremental region R2.

[0112] This variation (four (grayscale) scheme) can also help increase the amount of light received in the light-receiving part 4D. This can help improve the insufficient amount of light received in the light-receiving part 4D.

[0113] Specifically, in this modified example, third surfaces 33A and 33B with different tilt structures D1 are provided. Furthermore, the third light-receiving group 43 has light-receiving groups provided for "even-numbered sides" and light-receiving groups provided for "odd-numbered sides". This allows the processor 7 to detect "errors" caused by accidental reflection or obstruction of light due to an incoming foreign object, based on the light-receiving signals from the "even-numbered sides" and "odd-numbered sides" light-receiving groups.

[0114] Assume that light is shone onto the third light-receiving element 403 in the third light-receiving group 43C, which has an even number of light sources on both sides. If "0, 1" information is detected in the light-receiving signals supplied by two first light-receiving elements 401 arranged on both sides of a first light-receiving element 401 adjacent to the third light-receiving element 403, the processor 7 determines that there is an "error" caused by a foreign object. In short, this variant has a function similar to parity checking.

[0115] As described above, the third light-receiving group 43 of this modified example includes two light-receiving groups 43C and 43D used for parity checking. The two light-receiving groups 43C and 43D are respectively arranged on the side closer to the reflective part 3D than the first light-receiving group 41 and the second light-receiving group 42; and on the side farther from the reflective part 3D than the first light-receiving group 41 and the second light-receiving group 42.

[0116] The processor 7 outputs the judgment result to an external device (such as a control device for controlling a motor). By combining this judgment with the judgment related to the breakage of the reciprocal relationship based on the light-receiving signals obtained from the first light-receiving group 41 and the second light-receiving group 42 as described in the basic example, "errors" caused by foreign objects can be detected more accurately.

[0117] (3.4) Fourth variation

[0118] refer to Figure 8 Let's illustrate the fourth variation.

[0119] Figure 8 The reflective portion 3E and the light-receiving portion 4E of this modified example are schematically shown. The reflective portion 3E has multiple reflective regions 30, including multiple M-code regions R1 and incremental regions R2 arranged in a row. Similar to the third modified example, this modified example differs from the basic example in that the reflective portion 3E includes two types of third surfaces 33 (third surfaces 33A and third surfaces 33B). Figure 8In the figure, the different tilt angles of multiple reflective regions 30 are shown by points of different concentrations. In this figure, reflective regions 30 with points of the same concentration have the same tilt angle.

[0120] In this modified example, the light-receiving part 4E has a first light-receiving group 41 and a second light-receiving group 42 that correspond to and receive light from one or more first surfaces 31 and one or more second surfaces 32 of the reflective part 3E, respectively. Furthermore, this modified example differs from the basic example in that the first light-receiving group 41 and the second light-receiving group 42 of the light-receiving part 4E also receive reflected light C2 (two-level grayscale scheme) from the third surfaces 33A and 33B.

[0121] Similar to the third modification, the light-receiving section 4E in this modification has two third light-receiving groups 43 (43E, 43F). However, the first light-receiving group 41 and the third light-receiving group 43E are shared by each other. Furthermore, the second light-receiving group 42 and the third light-receiving group 43F are shared by each other. The third light-receiving group 43E is a light-receiving group provided for "even numbers on both sides". The third light-receiving group 43F is a light-receiving group provided for "odd numbers on both sides".

[0122] Similar to the third variation, a third surface 33A is provided for the incremental region R2, wherein the sum of the code information of the M-code regions R1 existing on both sides of the incremental region R2 is even. Similar to the third variation, a third surface 33B is provided for the incremental region R2, wherein the sum of the code information of the M-code regions R1 existing on both sides of the incremental region R2 is odd.

[0123] In this modified example, the tilt angle of the third surface 33A, represented by "θ3A", relative to the reference plane is set to be the same as the tilt angle "θ1" of each of the first surfaces 13 (i.e., θ3A = θ1). As a result, the reflected light C2 from the third surface 33A is received by the first light receiving group 41 (the third light receiving group 43E), which is the same as the light receiving group for the first surface 31.

[0124] Furthermore, in this modified example, the tilt angle of the third surface 33B, represented by "θ3B", relative to the reference plane is set to be the same as the tilt angle "θ2" of each of the second surfaces 32 (i.e., θ3B = θ2). As a result, the reflected light C2 from the third surface 33B is received by the second light receiving group 42 (the third light receiving group 43F), which is the same as the light receiving group for the second surface 32.

[0125] In short, in this modified example, the plurality of incremental regions R2 have: a first incremental region whose surface (third surface 33A) has the same tilt structure as the first surface 31; and a second incremental region whose surface (third surface 33B) has the same tilt structure as the second surface 32. A first light-receiving group 41 is arranged to receive reflected light C2 reflected from the first incremental region (third surface 33A). A second light-receiving group 42 is arranged to receive reflected light C2 reflected from the second incremental region (third surface 33B).

[0126] Similar to the third modification, this modification has a parity check function. Furthermore, compared to the third modification, this modification has advantages in simplifying the structure and reducing the size of the light-receiving part 4E. Additionally, the reflective part 3E can help reduce the number of types of tilt angles. Figure 8 The concentration pattern of the dots shown is only of "two types", which helps to simplify manufacturing.

[0127] (3.5) Fifth variation

[0128] refer to Figure 9 Let's illustrate the fifth variation.

[0129] Figure 9 The reflective portion 3F and the light-receiving portion 4F of this modified example are schematically shown. The reflective portion 3F has a plurality of reflective regions 30 including a plurality of M-code regions R1 arranged in a row. Although the modified example has been described with respect to the two M-code regions R1 including the information “0” and “1” in the reflective regions 30, the plurality of reflective regions 30 may also include incremental regions R2.

[0130] In the basic example, the first surface 31 and the second surface 32, corresponding to the code information "0" and "1" respectively, are each flat surfaces having an inclined structure D1 composed of an inclined surface of one type. In this modified example, the first surface 31 and the second surface 32 are each of two or more types (in... Figure 9 The example consists of three types of inclined surfaces (multi-level inclined scheme). Figure 9 In the figure, the different tilt angles of multiple reflective regions 30 are shown by points of different concentrations. Reflective regions 30 with points of the same concentration have the same tilt angle. It should be noted that the tilt directions in the first surface 31 and the second surface 32 are different from each other.

[0131] The first surface 31 is composed of five inclined surfaces 311 to 315 arranged sequentially from top to bottom. Inclined surfaces 311 and 315 have the same inclination angle as each other. Inclined surfaces 312 and 314 have the same inclination angle as each other. For example, inclined surface 313 may be a surface that is approximately parallel to a reference plane. Inclined surfaces 311, 312, 314 and 315 are each inclined downwards in a manner that is further away from the light-receiving part 4F than the center of the reflective part 3F on the outer side of the radial direction A2.

[0132] The tilt angles of inclined surfaces 311 to 315 can be set to satisfy the relationship “0≈θ13<θ12<θ11”, where “θ11” represents the tilt angle of inclined surfaces 311 and 315 respectively, “θ12” represents the tilt angle of inclined surfaces 312 and 314 respectively, and “θ13” represents the tilt angle of inclined surface 313.

[0133] The second surface 32 is composed of five inclined surfaces 321 to 325 arranged sequentially from the top. Inclined surfaces 321 and 325 have the same inclination angle as each other. Inclined surfaces 322 and 324 have the same inclination angle as each other. Inclined surfaces 321 to 325 are each inclined upwards in a manner that is closer to the light-receiving part 4F than the center of the reflective part 3F on the outer side of the radial direction A2.

[0134] The tilt angles of inclined surfaces 321 to 325 can be set to satisfy the relationship “θ11<θ21<θ22<θ23”, where “θ21” represents the tilt angle of inclined surfaces 321 and 325 respectively, “θ22” represents the tilt angle of inclined surfaces 322 and 324 respectively, and “θ23” represents the tilt angle of inclined surface 323.

[0135] In this modified example, the light-receiving part 4F has a total of six light-receiving groups 40. Three of these six light-receiving groups 40 are first light-receiving groups 41 (411 to 413), and the remaining three of these six light-receiving groups 40 are second light-receiving groups 42 (421 to 423).

[0136] A multi-level tilting scheme is adopted in the reflective part 3F, in which the first surface 31 and the second surface 32 are each composed of multiple types of tilted surfaces. As a result, as Figure 9 As shown, the light-receiving unit 4F outputs a light-receiving signal, in which the code information "0" and "1" in the light-receiving signal are graded in a manner that changes continuously like an analog signal.

[0137] Compared to the case where multiple code regions are set in each of multiple columns (for example, referring to the optical encoder 1X of the comparative example), this modification can also help increase the amount of light received in the light-receiving section 4F. This can help improve insufficient light received in the light-receiving section 4F.

[0138] In this modified example, a multi-level tilting scheme is employed in the reflective part 3F, in which the first surface 31 and the second surface 32 are each composed of multiple types of tilted surfaces. This allows this modified example to be used not only for M-code but also for Gray code.

[0139] By employing multi-level skewing as in this variant, more information can be obtained from an array (achieving data compression with a higher compression ratio). For example, consider the following 9-bit M-code array.

[0140] [Table 1]

[0141]

[0142] Regarding the 9-bit M-code array, the surface can be tilted in multiple levels, with each tilt representing 3 bits of information. Specifically, for the first 3 bits of information "001" = "1 (decimal number)", one type of tilt surface is prepared. For the next 3 bits of information "011" = "3 (decimal number)", another type of tilt surface is prepared. For the next 3 bits of information "010" = "2 (decimal number)", yet another type of tilt surface is prepared. ... In this way, multiple levels of tilting can help compress the data. In the bit arrays obtained by merging 3 bits from each of the 9 bits, adjacent bit arrays are different from each other in terms of the bit pattern they arrange. That is, when the rotating plate 5 rotates, the detection area moves into different arrays in the order of "1 (decimal number)", "3 (decimal number)", and "2 (decimal number)". This can generate a pattern similar to the M-code. In summary, multiple code regions R0 have different tilt structures D1. The skewed structure D1 corresponds to a bit array. Each bit array consists of m bits, where "m" is a natural number less than "n". Adjacent bit arrays are different from each other in terms of the bit pattern they arrange. In the example above, n=9 and m=3.

[0143] Furthermore, in the application example of this variant, the optical encoder 1 can be applied to Manchester encoding (see reference). Figure 10 The reflective part 3G and the light-receiving part 4G). In Figure 10In the example, the first surface 31 corresponding to the code information "0" has two types of inclined surfaces 311 and 312 from the top. Similarly, the second surface 32 corresponding to the code information "1" has two types of inclined surfaces 321 and 322 from the top. It should be noted that the tilt angle and tilt direction of the inclined surface 311 of the first surface 31 are the same as those of the inclined surface 322 of the second surface 32. Furthermore, the tilt angle and tilt direction of the inclined surface 312 of the first surface 31 are the same as those of the inclined surface 321 of the second surface 32. In the light-receiving section 4G, the light-receiving group 40 in the left column is referred to as the "low" group, and the light-receiving group 40 in the right column is referred to as the "high" group. This structure can provide light-receiving signals that represent information "0" by falling (from "high" to "low") and information "1" by rising (from "low" to "high") (see reference). Figure 10 The irradiated areas Op1A and Op1B).

[0144] In another application example of this variation, for instance, the optical encoder 1 can be applied to a decimal system by preparing 10 types of tilts (see reference). Figure 11 The reflective part 3H and the light-receiving part 4H). In Figure 11 In the example, the reflective portion 3H has a reflective region 30, each having one of 10 inclined surfaces (in Figure 11 In this example, only four types of tilted surfaces corresponding to "3", "9", "0", and "5" are shown respectively. The light-receiving section 4H has 10 rows of light-receiving groups 40 arranged in the radial direction A2. In the light-receiving section 4H of this example, light rays C2 reflected from the reflection areas 30 of the tilted surfaces corresponding to "3", "9", "0", and "5" respectively are irradiated onto the respective irradiated areas Op4 of the light-receiving groups 40 in the corresponding rows.

[0145] (3.6) Sixth variation

[0146] refer to Figure 14 and Figure 15 Let's illustrate the sixth variation.

[0147] Figure 14 This is a schematic cross-sectional view of the main part of the optical encoder 1 in this modified example. Figure 15 This diagram illustrates the positional relationship between the reflective portion 3K and the light-receiving portion (first light-receiving portion 4I) included in the optical encoder 1. In this modified example of the optical encoder 1, as... Figure 15 As shown, the multiple reflection regions 30 of the reflective portion 3K include multiple code regions R0 (M code regions R1) arranged in a row. Furthermore, the multiple reflection regions 30 of the reflective portion 3K also include multiple incremental regions R2 (see reference). Figure 14 Note that in Figure 15The illustration of the incremental region R2 is omitted in the text.

[0148] The rotating plate 5 is formed in the shape of a disc. Figure 14 A cross-sectional view of the peripheral region of the rotating plate 5, cut along its central axis, is shown. Multiple M-code regions R1 (code regions R0) are arranged along the circumference of the rotating plate 5 on its peripheral region. Multiple incremental regions R2 are arranged inside the multiple M-code regions R1 (closer to the central axis of the rotating plate 5). The multiple incremental regions R2 are arranged adjacent to the multiple M-code regions R1 and along the circumference of the rotating plate 5. In short, when viewed from above on one surface 50 (the upper surface) of the rotating plate 5, the multiple M-code regions R1 are arranged in a ring-like pattern along the periphery of the rotating plate 5, and the multiple incremental regions R2 are arranged in a ring-like pattern inside the multiple M-code regions R1, such that the multiple M-code regions R1 and the multiple incremental regions R2 are concentric.

[0149] In other words, in this variant, the incremental region R2 is arranged in a different column than the column where the multiple M-code regions R1 are arranged. In other words, the multiple reflection regions 30 also include multiple incremental regions R2 corresponding to the incremental tracks. The multiple incremental regions R2 are periodically arranged at predetermined intervals in a different column than the column containing the multiple code regions R0 (M-code regions R1).

[0150] In this variation, such as Figure 14 As shown, multiple incremental regions R2 have surfaces, each of which has a planar structure that is not tilted relative to the reference plane. Figure 14 In the example, each face of the multiple incremental regions R2 is approximately flush with one surface 50 (upper surface) of the rotating plate 5.

[0151] like Figure 14 As shown, in this modified example, the optical encoder 1 includes a first light-receiving part 4I for receiving reflected light C2 reflected from the M code region R1 and a second light-receiving part 4J for receiving reflected light C2 reflected from the incremental region R2, serving as the light-receiving part for receiving reflected light C2.

[0152] In this modified example, the multiple M-code regions R1 include four types of tilted surfaces (reflective surfaces), namely, the first tilted surface 30A, the second tilted surface 30B, the third tilted surface 30C, and the fourth tilted surface 30D. For example... Figure 14 and Figure 15 As shown, the first inclined surface 30A to the fourth inclined surface 30D have different inclination angles. Each of the first inclined surface 30A to the fourth inclined surface 30D has a curved inclined structure that gradually recesses below one surface 50 (upper surface) of the rotating plate 5. Figure 15In the diagram, the difference in tilt angle between the first tilted surface 30A and the fourth tilted surface 30D is shown by the difference in concentration at the points.

[0153] For example, the tilt angle is set to satisfy the relationship "θ31<θ32<θ33<θ34", where "θ31", "θ32", "θ33", and "θ34" represent the tilt angles of the first tilt surface 30A to the fourth tilt surface 30D relative to the reference plane, respectively. For example, the tilt angle of each of the first tilt surface 30A to the fourth tilt surface 30D can be defined as the tilt angle of the line segment connecting the two ends of the tilted curved surface. The first tilt surface 30A to the fourth tilt surface 30D have features that allow the reflected light C2 to be concentrated on the first light-receiving part 4I (see reference). Figure 15 The radius of curvature of the irradiated regions Op1, Op2, Op3, Op4.

[0154] exist Figure 14 In this diagram, for ease of illustration of reflected light C2, the first inclined surface 30A, the second inclined surface 30B, the third inclined surface 30C, and the fourth inclined surface 30D are arranged sequentially from back to front. It should be noted that this order is consistent with... Figure 15 The order shown is different (in) Figure 15 In the middle, they are arranged from top to bottom in the order of second inclined surface 30B, first inclined surface 30A, fourth inclined surface 30D and third inclined surface 30C.

[0155] In this variation, the first tilted surface 30A to the fourth tilted surface 30D have four tilted structures D1 corresponding to the number of hues in the M-code array compressed with four (grayscale) levels. Specifically, for example, the information "00 (in M-code array)" = "0 (in quaternary representation)" is associated with the first tilted surface 30A having a tilt angle "θ31". Similarly, another information "01 (in M-code array)" = "1 (in quaternary representation)" is associated with the second tilted surface 30B having a tilt angle "θ32". Yet another information "10 (in M-code array)" = "2 (in quaternary representation)" is associated with the third tilted surface 30C having a tilt angle "θ33". And yet another information "11 (in M-code array)" = "3 (in quaternary representation)" is associated with the fourth tilted surface 30D having a tilt angle "θ34".

[0156] In short, the reflective part 3K includes three or more types (four types in this variation) of reflective regions with different tilting structures.

[0157] Therefore, a tilted structure includes information corresponding to the two compressed data of the M-code array. This can be achieved by utilizing a smaller area to be illuminated with reflected light C2, similar to the optical encoder 1X of the comparative example (reference). Figure 4 The absolute position information is obtained at the same resolution as the first tilted surface 30A to the fourth tilted surface 30D. In addition, the curvature (radius) of each of the first tilted surface 30A to the fourth tilted surface 30D can focus the light, which improves the light utilization efficiency.

[0158] The first light-receiving part 4I will be described in detail. For example... Figure 15 As shown, the first light-receiving part 4I has four light-receiving groups 40 (first light-receiving group 41, second light-receiving group 42, third light-receiving group 43 and fourth light-receiving group 44) that correspond to and receive light from the first inclined surface 30A to the fourth inclined surface 30D of the reflective part 3K, respectively. The four light-receiving groups 40 are arranged along the radial direction A2.

[0159] The second light-receiving unit 4J has a light-receiving group comprising a plurality of light-receiving elements configured to receive reflected light C2 reflected from the incremental region R2, but its detailed description is omitted.

[0160] In this modified example, the first light-receiving part 4I and the second light-receiving part 4J are mounted on the substrate 6 on which the light source 2 is mounted. More specifically, in this modified example, the first light-receiving part 4I and the second light-receiving part 4J are mounted on one surface of the same substrate 6 from the central axis of the rotating plate 5 outward in the order of the second light-receiving part 4J, the light source 2, and the first light-receiving part 4I. Figure 14 On the lower surface of the middle. Figure 14 As shown, the light source 2 is mounted on the substrate 6 at a position roughly facing the boundary region between the M-code region R1 and the incremental region R2.

[0161] The first light-receiving group 41 includes a plurality of (four in a modified example) first light-receiving elements 401 arranged along one direction (column direction A1) to receive reflected light C2 reflected from the first inclined surface 30A.

[0162] The second light-receiving group 42 is arranged on a side farther from the reflector 3K than the first light-receiving group 41. The second light-receiving group 42 includes a plurality of (four in a modified example) second light-receiving elements 402 arranged along the column direction A1 to receive reflected light C2 reflected from the second inclined surface 30B.

[0163] The third light-receiving group 43 is arranged on the side farther from the reflector 3K than the second light-receiving group 42. The third light-receiving group 43 includes a plurality of (four in a modified example) third light-receiving elements 403 arranged along the column direction A1 to receive reflected light C2 reflected from the third inclined surface 30C.

[0164] The fourth light-receiving group 44 is arranged on the side farther from the reflector 3K than the third light-receiving group 43. The fourth light-receiving group 44 includes a plurality of (four in a modified example) fourth light-receiving elements 404 arranged along the column direction A1 to receive reflected light C2 reflected from the fourth inclined surface 30D.

[0165] In short, the light-receiving part (first light-receiving part 4I) has three or more light-receiving groups that correspond to and receive light from the three or more types (four types in this modified example) of the reflective part 3K respectively.

[0166] In this modified example, the reflected light C2 reflected from the first inclined surface 30A to the fourth inclined surface 30D will be focused onto any one of the light-receiving elements 401 to 404 arranged in the same row along the radial direction A2. That is, any one of the information “1,0,0,0”, “0,1,0,0”, “0,0,1,0”, and “0,0,0,1” will be detected from the four light-receiving elements (i.e., the first light-receiving elements 401 to 404 arranged in the same row along the radial direction A2). Figure 15 In the example, regarding the first light-receiving elements 401 to the fourth light-receiving elements 404 arranged in the top row, the reflected light C2 is received only by the second light-receiving element 402 (referencing the illumination area Op2), and the information "0,1,0,0" is detected from the light-receiving signals of these first light-receiving elements 401 to the fourth light-receiving elements 404.

[0167] For example, if the information "0,0,0,0" is detected in the light received signals from the first light-receiving element 401 to the fourth light-receiving element 404 arranged in the same row along the radial direction A2 due to light being blocked by a foreign object, the processor 7 determines that there is an "error" caused by a foreign object.

[0168] (3.7) Other variations

[0169] In the basic example, the first surface 31 and the second surface 32 are each flat, sloping surfaces with a straight line shape when viewed laterally (see reference). Figure 13 (A). Figure 13 A is a schematic side view of the first face 31 in the basic example. In an alternative example, at least one of the first face 31 and the second face 32 may include a curved surface. Figure 12 This is a schematic side view of one of the other variations of the reflective portion 3I. In the reflective portion 3I, the first surface 31 has a curved inclined structure 305 including an inclined curved surface. This structure has the advantage of increasing the possibility of converging the reflected light C2 and then illuminating the light-receiving portion 4, which further helps to improve the insufficient amount of light. Note that both the first surface 31 and the second surface 32 can have curved inclined structures 305, and their radii of curvature can be different from each other.

[0170] In the basic example, the first surface 31 and the second surface 32 are each flat, sloping surfaces with a straight line shape when viewed laterally (see reference). Figure 13(A). In an alternative example, at least one of the first surface 31 and the second surface 32 may be tilted with a concave-convex structure F1 (see reference). Figure 13 (B). Figure 13 B is a schematic side view of one of the other variations of the reflective part 3J. In the reflective part 3J, the first surface 31 is inclined with a sawtooth-shaped uneven structure F1 when viewed laterally. This structure has the advantage of increasing the possibility of reflecting light C2 onto the light-receiving part 4 according to the position of the light source 2.

[0171] In the basic example, the size ratio of the M code region R1 to the incremental region R2 in the radial direction A2 is 1:1, and the size ratio of the M code region R1 to the incremental region R2 in the circumferential direction of the rotating plate 5 is 1:1. However, these ratios are not limited to "1:1" and can be changed as needed.

[0172] In a variation of the basic example, similar to the sixth variation, multiple incremental regions R2 can be periodically arranged at predetermined intervals in a different column than the column where multiple M-code regions R1 are arranged. In this structure, similar to the sixth variation, each surface of the incremental region R2 can have a planar structure that is not tilted relative to the reference plane.

[0173] (Summarize)

[0174] As described above, the optical encoder (1) according to the first aspect includes a light source (2), a reflector (3, 3A to 3K), and a light receiver (4, 4C to 4J). The reflector (3, 3A to 3K) has a plurality of reflective regions (30), which include a plurality of M-code regions (R1) arranged in a row according to a specific bit pattern representing an M-code. The reflector (3, 3A to 3K) is configured to move together with the movement of the object (measurement object OB1) and is configured to reflect light from the light source (2) through one or more regions (detection regions X1) of the plurality of M-code regions (R1) corresponding to n bits, where n is a natural number. The light receiver (4, 4C to 4J) is configured to receive the reflected light (C2) from the reflector (3, 3A to 3K) for photoelectric conversion of the reflected light (C2). Multiple M-code regions (R1) have a first surface (31) corresponding to a first code information (B1) that is one of the bits of information in the M-code, and a second surface (32) corresponding to a second code information (B2) that is another bit of information in the M-code. The second surface (32) has an inclined structure (D1) that is different from the inclined structure of the first surface (31). The light-receiving part (4, 4C to 4J) has a first light-receiving group (41) and a second light-receiving group (42). The first light-receiving group (41) includes multiple first light-receiving elements (401) arranged along one direction (column direction A1) to receive reflected light (C2) reflected from the first surface (31). The second light-receiving group (42) is arranged on a side farther from the reflective part (3, 3A to 3K) than the first light-receiving group (41). The second light-receiving group (42) includes multiple second light-receiving elements (402) arranged along one direction (column direction A1) to receive reflected light (C2) reflected from the second surface (32). The first light-receiving group (41) and the second light-receiving group (42) are arranged such that the positions of the first light-receiving element (401) and the second light-receiving element (402) are offset from each other in a direction (column direction A1).

[0175] According to this aspect, the reflective section (3, 3A to 3K) has multiple reflective regions (30) including M-code regions (R1) arranged in a column. Furthermore, the first light-receiving element (401) and the second light-receiving element (402) that receive the reflected light (C2) are staggered relative to each other in one direction (column direction A1). Therefore, this aspect can help increase the amount of light received in the light-receiving section (4, 4C to 4J) by, for example, by utilizing a structure that serves as a countermeasure against phase shift of the received light signal. In other words, compared to the case where multiple M-code regions (R1) are provided in each of the two columns as a countermeasure against phase shift, this aspect can help increase the amount of light received in the light-receiving section (4, 4C to 4J). Therefore, insufficient light received in the light-receiving section (4, 4C to 4J) can be improved.

[0176] In the optical encoder (1) according to the second aspect, which can be implemented in conjunction with the first aspect, the plurality of reflective regions (30) also include a plurality of incremental regions (R2) corresponding to the incremental tracks. The plurality of incremental regions (R2) are arranged in a row periodically at predetermined intervals.

[0177] This aspect can help increase the amount of light received in the light-receiving section (4, 4C to 4J) compared to the case where the incremental region (R2) used to obtain the analog signal based on the incremental method is arranged in a different column than the column arranged with multiple M-code regions (R1).

[0178] In the optical encoder (1) according to the third aspect, which can be implemented in conjunction with the second aspect, multiple incremental regions (R2) each have a surface (third surface 33) with a tilt structure (D1) that is different from any tilt structure of the first surface (31) and the second surface (32).

[0179] This aspect can increase the possibility of accurately distinguishing analog signals (first code information B1 and second code information B2) based on incremental methods.

[0180] In the optical encoder (1) according to the fourth aspect, which can be implemented in conjunction with the first aspect, the plurality of reflective regions (30) further include a plurality of incremental regions (R2) corresponding to the incremental tracks. The plurality of incremental regions (R2) are periodically arranged in columns different from the first track at predetermined intervals.

[0181] Compared to the case where the incremental region (R2) used to obtain the analog signal based on the incremental method is arranged in the same column as the multiple M-code regions (R1), this aspect can increase the possibility of accurately distinguishing the analog signal based on the incremental method from the digital signal.

[0182] In the optical encoder (1) that can be implemented in conjunction with the fourth aspect according to the fifth aspect, multiple incremental regions (R2) each have a surface with a planar structure.

[0183] This aspect can help simplify the structure compared to cases where each face of multiple incremental regions (R2) has an inclined structure.

[0184] In the optical encoder (1) according to the sixth aspect, which can be implemented by combining any of the second to fifth aspects, the light-receiving part (4, 4C to 4J) also has a third light-receiving group (43). The third light-receiving group (43) includes a plurality of third light-receiving elements (403) arranged along one direction (column direction A1) to receive reflected light (C2) reflected from the surface (third surface 33) of the plurality of incremental regions (R2).

[0185] This aspect can increase the possibility of accurately distinguishing analog signals (first code information B1 and second code information B2) based on incremental methods.

[0186] In the optical encoder (1) according to the seventh aspect, which can be implemented in conjunction with the sixth aspect, the third light-receiving group (43) is arranged on either or both of the following: a side closer to the reflective part (3, 3A to 3K) than the first light-receiving group (41) and the second light-receiving group (42); and a side farther from the reflective part (3, 3A to 3K) than the first light-receiving group (41) and the second light-receiving group (42).

[0187] This aspect can increase the possibility of further accurately distinguishing analog signals (first code information B1 and second code information B2) based on incremental methods.

[0188] In the optical encoder (1) according to the eighth aspect, which can be implemented in conjunction with the seventh aspect, the third light-receiving group (43) includes two light-receiving groups (43C, 43D) for parity checking. The two light-receiving groups (43C, 43D) for parity checking are respectively arranged on the side closer to the reflector (3, 3A to 3K) than the first light-receiving group (41) and the second light-receiving group (42); and on the side farther from the reflector (3, 3A to 3K) than the first light-receiving group (41) and the second light-receiving group (42).

[0189] This aspect can help increase the amount of light received in the light-receiving section (4, 4C to 4J) while implementing the parity check function.

[0190] In the optical encoder (1) according to the ninth aspect, which can be implemented in conjunction with the second aspect, a plurality of incremental regions (R2) have a first incremental region whose surface has the same tilt structure as the tilt structure of the first surface (31). The plurality of incremental regions (R2) also have a second incremental region whose surface has the same tilt structure as the tilt structure of the second surface (32).

[0191] This aspect can help to further increase the amount of light received in the light-receiving parts (4, 4C to 4J).

[0192] In the optical encoder (1) according to the tenth aspect, which can be implemented in conjunction with the ninth aspect, a first light-receiving group (41) is arranged to receive reflected light (C2) reflected from a first incremental region. A second light-receiving group (42) is arranged to receive reflected light (C2) reflected from a second incremental region.

[0193] Since the first light-receiving group (41) and the second light-receiving group (42) each also serve as light-receiving groups for receiving reflected light (C2) reflected from the incremental region (R2), this aspect can help to further increase the amount of light received in the light-receiving section (4, 4C to 4J).

[0194] In the optical encoder (1) according to the eleventh aspect, which can be implemented by combining any one of the first aspect to the tenth aspect, at least one of the first surface (31) and the second surface (32) includes a curved surface.

[0195] This aspect can help increase the possibility of converging the reflected light (C2) and then illuminating the light-receiving part (4, 4C to 4J).

[0196] In the optical encoder (1) according to the twelfth aspect, which can be implemented by combining any of the first to eleventh aspects, at least one of the first surface (31) and the second surface (32) is tilted with a concave-convex structure (F1).

[0197] This aspect can help increase the possibility of illuminating the light-receiving part (4, 4C to 4J) with reflected light (C2) according to the position of the light source (2).

[0198] In the optical encoder (1) according to the thirteenth aspect, which can be implemented by combining any one of the first to twelfth aspects, the first surface (31) and the second surface (32) are each composed of two or more types of inclined surfaces.

[0199] This aspect can help to further increase the amount of light received in the light-receiving section (4, 4C to 4J) while achieving data compression with a higher compression ratio.

[0200] In the optical encoder (1) according to the fourteenth aspect, which can be implemented by combining any of the first to thirteenth aspects, the object (measurement object OB1) is a rotor. Reflectors (3, 3A to 3K) are provided on a rotating plate (5) that rotates together with the rotation of the object (measurement object OB1).

[0201] Based on this aspect, a rotary encoder that helps to improve the insufficient light reception in the light-receiving parts (4, 4C to 4J) has been realized.

[0202] The optical encoder (1) according to the fifteenth aspect includes a light source (2), a reflector (3, 3A to 3K), and a light receiver (4, 4C to 4J). The reflector (3, 3A to 3K) has multiple reflective regions (30), which include multiple code regions (R0) arranged in a row according to a specific positioning pattern. The reflector (3, 3A to 3K) is configured to move together with the movement of the object (measurement object OB1) and is configured to reflect light from the light source (2) through one or more regions (detection regions X1) of the multiple code regions (R0) corresponding to n bits, where n is a natural number. The light receiver (4, 4C to 4J) is configured to receive the reflected light (C2) from the reflector (3, 3A to 3K) for photoelectric conversion of the reflected light (C2). The reflector (3, 3A to 3K) includes three or more types of reflective regions (30) having different tilt structures (D1) from each other. The light-receiving part (4, 4C to 4J) has three or more light-receiving groups (41 to 43) that correspond to three or more types of reflective areas (30) and receive light from the three or more types of reflective areas (30).

[0203] According to this aspect, the reflective section (3, 3A to 3K) has multiple reflective regions (30) including code regions (R0) arranged in a row. Furthermore, the light-receiving section (4, 4C to 4J) has three or more light-receiving groups (41 to 43) that correspond to three or more types of reflective regions (30) and receive light from these reflective regions. Therefore, compared to the case where multiple code regions (R0) are provided in each of multiple columns, this aspect helps to increase the amount of light received in the light-receiving section (4, 4C to 4J). Thus, insufficient light received in the light-receiving section (4, 4C to 4J) can be improved.

[0204] In the optical encoder (1) according to the sixteenth aspect, which can be implemented in conjunction with the fifteenth aspect, multiple code regions (R0) have different tilt structures (D1) from each other. The tilt structures (D1) correspond to bit arrays respectively. Each bit array consists of m bits, where m is a natural number less than n. Adjacent bit arrays in the bit arrays are different from each other in terms of the bit patterns they are arranged.

[0205] This aspect can help to further increase the amount of light received in the light-receiving section (4, 4C to 4J) while achieving data compression with a higher compression ratio.

[0206] In the optical encoder (1) according to the seventeenth aspect, which can be implemented in conjunction with the fifteenth or sixteenth aspect, the plurality of reflective regions (30) also include a plurality of incremental regions (R2) corresponding to the incremental tracks. The plurality of incremental regions (R2) are periodically arranged in a column different from a column at predetermined intervals.

[0207] This aspect can help increase the likelihood of accurately distinguishing between analog signals and digital signals based on the incremental method, compared to the case where the incremental region (R2) used to obtain the analog signal based on the incremental method is arranged in the same column as the multiple code regions (R0).

[0208] In the optical encoder (1) according to the eighteenth aspect, which can be implemented in conjunction with the seventeenth aspect, multiple incremental regions (R2) have their own surfaces with planar structures.

[0209] This aspect can help simplify the structure compared to the case where each face of multiple incremental regions (R2) has an inclined structure.

[0210] Note that the constituent elements according to the second to fourteenth aspects are not essential constituent elements of the optical encoder (1) according to the first aspect, but can be appropriately omitted. The constituent elements according to the sixteenth to eighteenth aspects are not essential constituent elements of the optical encoder (1) according to the fifteenth aspect, but can be appropriately omitted.

[0211] Explanation of reference numerals in the attached figures

[0212] 1 Optical Encoder

[0213] 2 light sources

[0214] 3, 3A to 3K reflectors

[0215] 30 Reflection Area

[0216] 31 First page

[0217] 32 Second page

[0218] 4, 4C to 4J light-receiving sections

[0219] 41 First Light Receiving Group

[0220] 42 Second Light Receiving Group

[0221] 43 Third Light Receiving Group

[0222] 401 First Light Receiving Element

[0223] 402 Second light-receiving element

[0224] 5 rotating plates

[0225] Column A1 (one direction)

[0226] B1 First Code Information

[0227] B2 Second Code Information

[0228] C2 reflected light

[0229] D1 Inclined Structure

[0230] F1 Concave-convex structure

[0231] OB1 Measurement Object (Object)

[0232] R0 code area

[0233] R1M code area

[0234] R2 Incremental Region

[0235] X1 detection area

Claims

1. An optical encoder, comprising: light source; A reflective part having multiple reflective regions, the multiple reflective regions including multiple M-code regions arranged in a column according to a specific bit pattern representing an M-code, the reflective part being configured to move together with the movement of an object, the reflective part being configured to reflect light from the light source through one or more regions corresponding to n bits among the multiple M-code regions, where n is a natural number; as well as A light-receiving unit is configured to receive reflected light from the reflective unit and perform photoelectric conversion on the reflected light. The plurality of M-code regions have: The first face corresponding to the first code information, which is one of the bits of information in the M code, and The second surface, corresponding to the second code information which is another bit of information in the M code, has a tilt structure different from that of the first surface. The light-receiving part has: A first light-receiving group includes a plurality of first light-receiving elements arranged in one direction to receive reflected light reflected from the first surface, and The second light-receiving group is arranged on a side farther from the reflective portion than the first light-receiving group. The second light-receiving group includes a plurality of second light-receiving elements arranged along the first direction to receive reflected light reflected from the second surface. The first light-receiving group and the second light-receiving group are arranged such that the positions of the first light-receiving element and the second light-receiving element are offset from each other in one direction.

2. The optical encoder according to claim 1, wherein, The plurality of reflection regions also include a plurality of incremental regions corresponding to the incremental rails, and the plurality of incremental regions are periodically arranged in the column at predetermined intervals.

3. The optical encoder according to claim 2, wherein, The plurality of incremental regions each have a face with a tilt structure that is different from any tilt structure of the first face and the second face.

4. The optical encoder according to claim 1, wherein, The plurality of reflection regions also include a plurality of incremental regions corresponding to the incremental rail, the plurality of incremental regions being periodically arranged in columns different from the column at predetermined intervals.

5. The optical encoder according to claim 4, wherein, The multiple incremental regions each have a surface with a planar structure.

6. The optical encoder according to any one of claims 2 to 5, wherein, The light-receiving section also has a third light-receiving group, which includes a plurality of third light-receiving elements arranged along the one direction to receive reflected light reflected from the surfaces of the plurality of incremental regions.

7. The optical encoder according to claim 6, wherein, The third light-receiving group is arranged on any one or both of the following sides: The side closer to the reflective part than the first light-receiving group and the second light-receiving group, and The side farther from the reflective part than the first light-receiving group and the second light-receiving group.

8. The optical encoder according to claim 7, wherein, The third light-receiving group includes the two light-receiving groups used for parity checking. The two light-receiving groups used for parity checking are arranged on the following two sides: The side closer to the reflective part than the first light-receiving group and the second light-receiving group, and The side farther from the reflective part than the first light-receiving group and the second light-receiving group.

9. The optical encoder according to claim 2, wherein, The plurality of incremental regions have: The first incremental region has a surface with the same tilt structure as the first surface, and The second incremental region has a surface with the same tilt structure as the second surface.

10. The optical encoder according to claim 9, wherein, The first light-receiving group is arranged to receive reflected light from the first incremental region, and The second light-receiving group is arranged to receive reflected light from the second incremental region.

11. The optical encoder according to any one of claims 1 to 5, wherein, At least one of the first surface and the second surface includes a curved surface.

12. The optical encoder according to any one of claims 1 to 5, wherein, At least one of the first surface and the second surface is inclined with a concave-convex structure.

13. The optical encoder according to any one of claims 1 to 5, wherein, The first surface and the second surface are each composed of two or more types of inclined surfaces.

14. The optical encoder according to any one of claims 1 to 5, wherein, The object is a rotor, and The reflector is mounted on a rotating plate that rotates together with the object.

15. An optical encoder, comprising: light source; A reflective part having multiple reflective regions, the multiple reflective regions including multiple code regions arranged in a row according to a specific positioning pattern, the reflective part being configured to move together with the movement of an object, and the reflective part being configured to reflect light from the light source through one or more regions corresponding to n bits among the multiple code regions, where n is a natural number; as well as A light-receiving unit is configured to receive reflected light from the reflective unit and perform photoelectric conversion on the reflected light. The reflective portion includes three or more types of reflective regions with different tilting structures. The light-receiving part has three or more light-receiving groups, each of which corresponds to one of the three or more types of reflective areas and receives light from those areas. The multiple code regions have different slant structures, each corresponding to a bit array, where each bit array consists of m bits, where m is a natural number less than n. Adjacent bit arrays in the bit array are different from each other in terms of the bit patterns they are arranged.

16. The optical encoder according to claim 15, wherein, The plurality of reflection regions also include a plurality of incremental regions corresponding to the incremental rail, the plurality of incremental regions being periodically arranged in columns different from the column at predetermined intervals.

17. The optical encoder according to claim 16, wherein, The multiple incremental regions each have a surface with a planar structure.

Images