encoder

Abstract

This encoder comprises a rotary plate having a first pattern and a second pattern, a light emission part for emitting light, and a light reception part for receiving light, wherein: the first pattern is configured such that a first unit region which guides light emitted from the light emission part to the light reception part and a second unit region which does not guide light emitted from the light emission part to the light reception part are aligned in a circumferential direction about a rotation axis of the rotary plate; the second pattern is configured such that the first unit region which guides light emitted from the light emission part to the light reception part and the second unit region which does not guide light emitted from the light emission part to the light reception part are aligned in the circumferential direction about the rotation axis of the rotary plate; and the first unit region and the second unit region in the first pattern are arranged in such a manner as to be reverse to the first unit region and the second unit region in the second pattern in a direction orthogonal to a rotation direction of the rotary plate.

Description

【Technical Field】 【0001】 The present disclosure relates to an encoder. 【Background Art】 【0002】 Conventionally, an encoder for detecting the rotation of a motor's rotating shaft has been known. For example, Patent Document 1 discloses an encoder having a pattern along a measurement direction, a light source that emits light to the pattern, and a plurality of light receiving elements arranged along the measurement direction and configured to receive the light emitted from the light source and transmitted or reflected by the pattern. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2016-118486 【Summary of the Invention】 【0004】 An encoder according to one aspect of the present disclosure includes a rotating plate having a first pattern and a second pattern, an irradiation unit that irradiates the first pattern and the second pattern with light, and a light receiving unit that receives the light irradiated from the irradiation unit and passing through the first pattern and the light irradiated from the irradiation unit and passing through the second pattern. The first pattern and the second pattern have a configuration in which a first unit region that guides the light irradiated from the irradiation unit to the light receiving unit and a second unit region that does not guide the light irradiated from the irradiation unit to the light receiving unit are arranged in a circumferential direction centered on the rotation axis of the rotating plate. The order in which the first unit region and the second unit region are arranged in the first pattern and the order in which the first unit region and the second unit region are arranged in the second pattern are reversed. 【0005】 Furthermore, an encoder according to one aspect of the present disclosure comprises a rotating plate having a pattern, an illumination unit that irradiates light onto the pattern, and a light receiving unit that receives light irradiated from the illumination unit and passed through the pattern, wherein the pattern has a configuration in which a first unit region that guides light irradiated from the illumination unit to the light receiving unit and a second unit region that does not guide light irradiated from the illumination unit to the light receiving unit are arranged in the circumferential direction centered on the rotation axis of the rotating plate, and when the first unit region and the second unit region are referred to as unit regions, there is a first arrangement which is an arrangement of M unit regions for outputting position information indicating the position of a detection target, and a second arrangement which is an arrangement of N unit regions adjacent to the first arrangement which is an arrangement of N unit regions for outputting correction information for correcting the position information. 【0006】 According to this disclosure, an encoder that can suppress a decrease in detection accuracy can be provided. [Brief explanation of the drawing] 【0007】 [Figure 1] Figure 1 shows a motor equipped with an encoder according to an embodiment. [Figure 2A] Figure 2A shows the rotating plate of the encoder in Figure 1. [Figure 2B] Figure 2B shows the rotating plate of the encoder in Figure 1. [Figure 3] Figure 3 is a block diagram showing the functional configuration of the encoder in Figure 1. [Figure 4] Figure 4 is a diagram illustrating an example of the determination method used by the determination unit of the encoder shown in Figure 1. [Figure 5] Figure 5 shows an example of the light intensity received by the light receiving section of the encoder in Figure 1. [Figure 6] Figure 6 is a diagram illustrating an example of the determination method and correction method by the correction unit of the encoder shown in Figure 1. [Figure 7] Figure 7 shows a calculation circuit that calculates the values ​​for forming the first pattern on the rotating plate of the encoder shown in Figure 1. [Figure 8]Figure 8 shows a table containing the values ​​obtained by the calculation circuit in Figure 7. [Figure 9] Figure 9 shows the data flow during the operation of the correction unit of the encoder shown in Figure 1. [Figure 10] Figure 10 illustrates another example of the correction method used by the correction unit of the encoder shown in Figure 1. [Figure 11] Figure 11 is a diagram illustrating another example of the correction method used by the correction unit of the encoder shown in Figure 1. [Figure 12] Figure 12 illustrates yet another example of the correction method used by the correction unit of the encoder shown in Figure 1. [Figure 13] Figure 13 shows another example of the light intensity received by the light receiving section of the encoder in Figure 1. [Figure 14] Figure 14 shows a calculation circuit that calculates values ​​to form a first pattern different from the first pattern of the encoder in Figure 1. [Figure 15] Figure 15 is a table showing the values ​​obtained by the calculation circuit in Figure 14. [Modes for carrying out the invention] 【0008】 The embodiments of this disclosure will now be described. Note that the embodiments described below are all specific examples of this disclosure. Therefore, the numerical values, components, arrangement and connection configurations of components, as well as the processes and their sequences shown in the following embodiments, are examples only and are not intended to limit this disclosure. Accordingly, any components in the following embodiments that are not described in the independent claims representing the highest-level concepts of this disclosure will be described as arbitrary components. 【0009】 Furthermore, each figure is a schematic diagram and not necessarily a strictly accurate representation. In each figure, substantially identical components are denoted by the same reference numerals, and redundant explanations are omitted or simplified. 【0010】 (Embodiment) FIG. 1 is a diagram showing a motor 1 including an encoder 10 according to an embodiment. FIGS. 2A and 2B are diagrams showing a rotating plate 12 of the encoder 10 in FIG. 1. FIG. 2A is a view of the rotating plate 12 seen from the axial direction, and FIG. 2B is an enlarged view showing a portion surrounded by the dotted line in FIG. 2A. In FIG. 1, the case 6, the first pattern 24, and the second pattern 26 are shown in cross-section. In the following description, the axial direction refers to the direction in which the rotation axis A extends (see the arrow X in FIG. 1), the radial direction refers to the radial direction centered on the rotation axis A ( Figures 2A and 2B see the arrow Y), and the circumferential direction refers to the circumferential direction surrounding the rotation axis A centered on the rotation axis A (see the arrow Z in FIGS. 2A and 2B). The radial direction is perpendicular to the circumferential direction and the rotation axis. The configuration of the encoder 10 will be described with reference to FIGS. 1 and 2A and 2B. 【0011】 As shown in FIG. 1, the motor 1 includes a main body 2, a stator 3, a rotor 4, a rotating shaft 5, a case 6, and an encoder 10. 【0012】 The main body 2 is a housing that houses the stator 3, the rotor 4, etc. The stator 3 is fixed to the inner surface of the main body 2. The rotor 4 is provided rotatably with respect to the stator 3. 【0013】 The rotating shaft 5 is in the shape of a rod such as a cylinder, is fixed to the inner surface of the rotor 4, and rotates around the rotation axis A. For example, when power is supplied to the motor 1, the rotating shaft 5 rotates around the rotation axis A together with the rotor 4 based on the power. An encoder 10 is provided at one axial end of the rotating shaft 5. At the other axial end of the rotating shaft 5, a load (not shown) or the like that is rotationally driven by the rotation of the rotating shaft 5 is attached. For example, the rotating shaft 5 is formed of a magnetic metal such as iron. 【0014】 The case 6 is attached to the main body 2 so as to cover one axial end of the rotating shaft 5 and the encoder 10, etc. For example, the case 6 is formed of a magnetic metal such as iron. 【0015】 The encoder 10 detects the rotation of the object to be detected. Specifically, the encoder 10 detects the position (rotational position), rotational direction, and rotational speed of the object to be detected. In this embodiment, the object to be detected is the rotating shaft 5. That is, the encoder 10 detects the position of the rotating shaft 5, the rotational direction of the rotating shaft 5, and the rotational speed of the rotating shaft 5. 【0016】 As described above, the encoder 10 is provided at one end of the rotation shaft 5 in the axial direction. As shown in Figures 1, 2A, and 2B, the encoder 10 comprises a rotating plate 12, a first substrate 14, a second substrate 16, an illumination unit 18, and a light receiving unit 20. 【0017】 The rotating plate 12 is a rotating plate that rotates with the rotation axis A as its center of rotation, and has a main body 22, a first pattern 24, and a second pattern 26. 【0018】 The main body 22 is plate-shaped, extending in a direction perpendicular to the axial direction, and is circular when viewed from the axial direction. The main body 22 is attached to one end of the rotation shaft 5 in the axial direction and rotates together with the rotation shaft 5 about the rotation axis A as the center of rotation. The axis of the main body 22 and the rotation axis A coincide. For example, the main body 22 is made of transparent glass or the like that transmits light. 【0019】 The first pattern 24 is provided on the main surface of the main body 22 on the side of the first substrate 14. The first pattern 24 is provided in an annular shape along the circumferential direction. The first pattern 24 rotates together with the main body 22. In this embodiment, the first pattern 24 is an absolute pattern. The first pattern 24 has a plurality of first light guide portions 28 and a plurality of first non-light guide portions 30. 【0020】 Multiple first light guide units 28 are arranged in a line with spacing between them in the circumferential direction. Each of the multiple first light guide units 28 is composed of first unit regions 32 arranged in the circumferential direction that guide light emitted from the illumination unit 18 to the light receiving unit 20. In other words, each of the multiple first light guide units 28 is a region composed of one or more first unit regions 32 that guides light emitted from the illumination unit 18 to the light receiving unit 20. The first unit region 32 is a region of a predetermined size. For example, the first unit region 32 is formed of transparent glass or the like that transmits light. 【0021】 The number of first unit regions 32 constituting each of the multiple first light guide sections 28 is not uniform. The dimensions of each of the multiple first light guide sections 28 in the circumferential direction are determined by the number of first unit regions 32 constituting that first light guide section 28, and the dimensions of each of the multiple first light guide sections 28 in the circumferential direction are not uniform. Note that in Figure 2B, only some of the first unit regions 32 are shown to avoid making the drawing complicated (see dashed line). 【0022】 Multiple first non-light-guide sections 30 are arranged in a line with spacing between them in the circumferential direction. Specifically, each of the multiple first non-light-guide sections 30 is positioned between adjacent first light-guide sections 28. In other words, the first pattern 24 has a configuration in which the first light-guide sections 28 and the first non-light-guide sections 30 are arranged alternately in the circumferential direction. Each of the multiple first non-light-guide sections 30 is composed of second unit regions 34 arranged in the circumferential direction that do not guide the light irradiated from the irradiation section 18 to the light-receiving section 20. In other words, each of the multiple first non-light-guide sections 30 is a region composed of one or more second unit regions 34, which, when light is irradiated from the irradiation section 18, does not transmit the light and does not guide it to the light-receiving section 20. The second unit region 34 is a region of a predetermined size, which, when light is irradiated from the irradiation section 18, does not transmit the light and does not guide it to the light-receiving section 20. The size of the second unit region 34 is the same as the size of the first unit region 32. For example, the second unit region 34 is formed by a black chrome plating or the like that does not transmit light. 【0023】 The number of second unit regions 34 constituting each of the multiple first non-light-guide portions 30 is not uniform. The dimensions of each of the multiple first non-light-guide portions 30 in the circumferential direction are determined by the number of second unit regions 34 constituting the first non-light-guide portion 30, and the dimensions of each of the multiple first non-light-guide portions 30 in the circumferential direction are not uniform. Note that in Figure 2B, only some of the second unit regions 34 are shown to avoid making the drawing complicated (see dashed line). 【0024】 As described above, each of the multiple first light guides 28 is composed of one or more first unit regions 32 arranged in the circumferential direction, and each of the multiple first non-light guides 30 is composed of one or more second unit regions 34 arranged in the circumferential direction. In other words, the first pattern 24 has a configuration in which the first unit regions 32 and the second unit regions 34 are arranged in the circumferential direction. 【0025】 The second pattern 26 is provided on the main surface of the main body 22 on the side of the first substrate 14. The second pattern 26 is provided radially inward from the first pattern 24 and is provided in an annular shape along the circumferential direction. The second pattern 26 rotates together with the main body 22. In this embodiment, the second pattern 26 is an absolute pattern. The second pattern 26 has a plurality of second light guide portions 36 and a plurality of second non-light guide portions 38. 【0026】 Multiple second light guide units 36 are arranged in a line with spacing between them in the circumferential direction. Each of the multiple second light guide units 36 is composed of first unit regions 40 arranged in the circumferential direction that guide light emitted from the irradiation unit 18 to the light receiving unit 20. In other words, each of the multiple second light guide units 36 is a region composed of one or more first unit regions 40 that guides light emitted from the irradiation unit 18 to the light receiving unit 20. The first unit region 40 is a region of a predetermined size that transmits light from the irradiation unit 18 and guides it to the light receiving unit 20. The size of the first unit region 40 in the second pattern 26 is different from the size of the first unit region 32 in the first pattern 24. For example, the first unit region 40 is formed of transparent glass or the like that transmits light. 【0027】 The number of first unit regions 40 constituting each of the multiple second light guide sections 36 is not uniform. The dimensions of each of the multiple second light guide sections 36 in the circumferential direction are determined by the number of first unit regions 40 constituting that second light guide section 36, and the dimensions of the multiple second light guide sections 36 in the circumferential direction are not uniform. Note that in Figure 2B, only some of the first unit regions 40 are shown to avoid making the drawing complicated (see dashed line). 【0028】 Each of the multiple second light guides 36 corresponds to each of the multiple first non-light guides 30. In this embodiment, each of the multiple second light guides 36 is radially adjacent to the corresponding first non-light guide among the multiple first non-light guides 30. The number of first unit regions 40 constituting the second light guide 36 is the same as the number of second unit regions 34 constituting the first non-light guide 30 corresponding to the second light guide 36. 【0029】 In other words, each of the multiple first unit regions 40 in the second pattern 26 corresponds to each of the multiple second unit regions 34 in the first pattern 24. In this embodiment, each of the multiple first unit regions 40 in the second pattern 26 is radially adjacent to the corresponding second unit region 34 among the multiple second unit regions 34 in the first pattern 24. 【0030】 Multiple second non-light-guiding sections 38 are arranged in a line with spacing between them in the circumferential direction. Specifically, each of the multiple second non-light-guiding sections 38 is positioned between adjacent second light-guiding sections 36. In other words, the second pattern 26 has a configuration in which the second light-guiding sections 36 and the second non-light-guiding sections 38 are arranged alternately in the circumferential direction. Each of the multiple second non-light-guiding sections 38 is composed of second unit regions 42 arranged in the circumferential direction that do not guide the light irradiated from the irradiation section 18 to the light-receiving section 20. In other words, each of the multiple second non-light-guiding sections 38 is a region composed of one or more second unit regions 42, which, when light is irradiated from the irradiation section 18, does not transmit the light and does not guide it to the light-receiving section 20. The second unit region 42 is a region of a predetermined size, which, when light is irradiated from the irradiation section 18, does not transmit the light and does not guide it to the light-receiving section 20. The size of the second unit region 42 is the same as the size of the first unit region 40. However, the size of the second unit region 42 in the second pattern 26 is different from the size of the second unit region 34 in the first pattern 24. For example, the second unit region 42 is formed by a black chrome plating or the like that does not transmit light. 【0031】 The number of second unit regions 42 constituting each of the multiple second non-light-guide portions 38 is not uniform. The dimensions of each of the multiple second non-light-guide portions 38 in the circumferential direction are determined by the number of second unit regions 42 constituting the second non-light-guide portion 38, and the dimensions of each of the multiple second non-light-guide portions 38 in the circumferential direction are not uniform. Note that in Figure 2B, only some of the second unit regions 42 are shown to avoid making the drawing complicated (see dashed line). 【0032】 Each of the multiple second non-light-guide portions 38 corresponds to each of the multiple first light-guide portions 28. In this embodiment, each of the multiple second non-light-guide portions 38 is radially adjacent to the corresponding first light-guide portion 28 among the multiple first light-guide portions 28. The number of second unit regions 42 constituting the second non-light-guide portion 38 is the same as the number of first unit regions 32 constituting the first light-guide portion 28 corresponding to the second non-light-guide portion 38. 【0033】 In other words, each of the multiple second unit regions 42 in the second pattern 26 corresponds to each of the multiple first unit regions 32 in the first pattern 24. In this embodiment, each of the multiple second unit regions 42 in the second pattern 26 is radially adjacent to the corresponding first unit region 32 among the multiple first unit regions 32 in the first pattern 24. 【0034】 As described above, each of the multiple second light guides 36 is composed of one or more first unit regions 40 arranged in the circumferential direction, and each of the multiple second non-light guides 38 is composed of one or more second unit regions 42 arranged in the circumferential direction. In other words, the second pattern 26 has a configuration in which the first unit regions 40 and the second unit regions 42 are arranged in the circumferential direction. 【0035】 Furthermore, each of the multiple first unit regions 40 in the second pattern 26 corresponds to each of the multiple second unit regions 34 in the first pattern 24, and each of the multiple second unit regions 42 in the second pattern 26 corresponds to each of the multiple first unit regions 32 in the first pattern 24. The order in which the first unit regions 32 and second unit regions 34 are arranged in the first pattern 24 is reversed from the order in which the first unit regions 40 and second unit regions 42 are arranged in the second pattern 26. In the first pattern 24, the first unit region 32 and the second unit region 34 are arranged to be reversed in the direction perpendicular to the rotation direction of the rotating plate 12 (arrow B) (radial direction, arrow Y) with respect to the first unit region 40 and the second unit region 42 in the second pattern 26. That is, the first unit region 32 in the first pattern 24 and the second unit region 42 in the second pattern 26 are aligned in the radial direction, while the second unit region 34 in the first pattern 24 and the first unit region 40 in the second pattern 26 are aligned in a different radial direction. 【0036】 When light from the illumination unit 18 is irradiated onto the first unit region 32, a second pattern 26 is provided so that light from the illumination unit 18 is also irradiated onto the second unit region 42 corresponding to the first unit region 32. Furthermore, when light from the illumination unit 18 is irradiated onto the second unit region 34, a second pattern 26 is provided so that light from the illumination unit 18 is also irradiated onto the first unit region 40 corresponding to the second unit region 34. By providing the second pattern 26 in this way, the output value of the first light receiving member 48 and the output value of the second light receiving member 50 can be inverted. In other words, the second pattern 26 is provided so that the output value of the second light receiving member 50 is the inverted value of the output value of the first light receiving member 48. 【0037】 As shown in Figure 1, the first substrate 14 extends in a direction perpendicular to the axial direction. The first substrate 14 is provided at a distance from the rotating plate 12 in the axial direction and faces the rotating plate 12. The first substrate 14 is fixed to the inner surface of the case 6 and does not rotate with the rotating shaft 5. 【0038】 The second substrate 16 extends in a direction perpendicular to the axial direction. The second substrate 16 is provided at a distance from the rotating plate 12 in the axial direction and faces the rotating plate 12. The second substrate 16 is provided on the opposite side of the rotating plate 12 from the first substrate 14. The second substrate 16 is fixed to the inner surface of the case 6 and does not rotate with the rotating shaft 5. 【0039】 The irradiation unit 18 has a first light-emitting unit 44 and a second light-emitting unit 46, and irradiates the first pattern 24 and the second pattern 26 with light. 【0040】 The first light-emitting unit 44 is mounted on the first substrate 14 so as to face the first pattern 24 in the axial direction, and illuminates the first pattern 24 with light. For example, the first light-emitting unit 44 can be implemented by a light-emitting module or the like. 【0041】 The second light-emitting unit 46 is mounted on the first substrate 14 so as to face the second pattern 26 in the axial direction, and irradiates the second pattern 26 with light. For example, the second light-emitting unit 46 can be realized by a light-emitting module or the like. 【0042】 The light-receiving unit 20 receives light that is irradiated from the irradiation unit 18 onto the first pattern 24 and passes through the first pattern 24, and light that is irradiated from the irradiation unit 18 onto the second pattern 26 and passes through the second pattern 26. The light-receiving unit 20 has a first light-receiving member 48 and a second light-receiving member 50. 【0043】 The first light-receiving member 48 is mounted on the second substrate 16 so as to face the first pattern 24 in the axial direction, and receives light transmitted through the first pattern 24. The first light-receiving member 48 also binarizes the intensity of the received light and outputs it. For example, the first light-receiving member 48 can be realized by a light-receiving element or the like. 【0044】 The second light-receiving member 50 is mounted on the second substrate 16 so as to face the second pattern 26 in the axial direction, and receives light transmitted through the second pattern 26. The second light-receiving member 50 also binarizes the intensity of the received light and outputs it. For example, the second light-receiving member 50 can be implemented by a light-receiving element or the like. 【0045】 Figure 3 is a block diagram showing the functional configuration of the encoder 10 in Figure 1. The functional configuration of the encoder 10 will be explained with reference to Figure 3. 【0046】 As shown in Figure 3, the encoder 10 further comprises a determination unit 52 and a correction unit 54. 【0047】 The first light-receiving member 48 binarizes the intensity of the received light and outputs it, then transmits it to the determination unit 52. Specifically, the first light-receiving member 48 compares the intensity of the received light with a predetermined threshold value and outputs one of two values ​​according to the result of the comparison. In this embodiment, the first light-receiving member 48 outputs "1" if the intensity of the received light is equal to or greater than the predetermined threshold value, and outputs "0" if the intensity of the received light is less than the predetermined threshold value. 【0048】 The second light-receiving member 50 binarizes the intensity of the received light and outputs it, which is then transmitted to the determination unit 52. Specifically, the second light-receiving member 50 compares the intensity of the received light with a predetermined threshold value and outputs one of two values ​​according to the result of the comparison. In this embodiment, the second light-receiving member 50 outputs "1" if the intensity of the received light is greater than or equal to the predetermined threshold value, and outputs "0" if the intensity of the received light is less than the predetermined threshold value. 【0049】 The determination unit 52 acquires the output values ​​of the first light-receiving member 48 and the second light-receiving member 50, and determines whether these output values ​​are incorrect. Specifically, if the output value of the second light-receiving member 50 is the inverse of the output value of the first light-receiving member 48, the determination unit 52 determines that the output values ​​of both the first light-receiving member 48 and the second light-receiving member 50 are correct and outputs the determination result. If the output value of the second light-receiving member 50 is not the inverse of the output value of the first light-receiving member 48, the determination unit 52 determines that either the output value of the first light-receiving member 48 or the output value of the second light-receiving member 50 is incorrect and outputs the determination result. For example, the determination unit 52 may be implemented by a processor or the like. 【0050】 For example, the determination unit 52 determines that if the output value of the first light-receiving member 48 is "1" and the output value of the second light-receiving member 50 is "0", then these output values ​​are not incorrect. The determination unit 52 determines that if the output value of the first light-receiving member 48 is "0" and the output value of the second light-receiving member 50 is "0", then either of these output values ​​is incorrect. 【0051】 If the determination unit 52 determines that either the output value of the first light-receiving member 48 or the output value of the second light-receiving member 50 is incorrect, the correction unit 54 determines whether the output value of the first light-receiving member 48 is incorrect. If the correction unit 54 determines that the output value of the first light-receiving member 48 is incorrect, it corrects the output value of the first light-receiving member 48 to the correct value and outputs it. The determination method and correction method by the correction unit 54 will be described later. For example, the correction unit 54 is implemented by a processor or the like. 【0052】 Figure 4 is a diagram illustrating an example of the determination method by the determination unit 52 of the encoder 10 in Figure 1. Figure 4(a) schematically shows the output values ​​of the first pattern 24 and the first light receiving member 48, Figure 4(b) schematically shows the output values ​​of the second pattern 26 and the second light receiving member 50, and Figure 4(c) shows the sum of the output values ​​of the first light receiving member 48 and the second light receiving member 50. Figure 5 is a diagram illustrating an example of the light reception intensity of light received by the light receiving unit 20 of the encoder 10 in Figure 1. Figure 5(a) shows an example of the light reception intensity of light received by the first light receiving member 48, and Figure 5(b) shows an example of the light reception intensity of light received by the second light receiving member 50. An example of the determination method by the determination unit 52 will be explained with reference to Figures 4 and 5. 【0053】 As shown in Figure 4(a), in the first pattern 24, the first unit region 32 and the second unit region 34 are aligned in the direction of rotation of the rotating plate 12 (see arrow B in Figure 4). Hereinafter, the direction of rotation of the rotating plate 12 will also be simply referred to as the rotation direction. The rotation direction coincides with the circumferential direction and follows the circumferential direction. The first unit region 32 and the second unit region 34 will also be simply referred to as unit regions. Here, when the first unit region 32 and the second unit region 34 are referred to as unit regions, the first pattern 24 has a first arrangement which is an arrangement of M unit regions for outputting position information indicating the position of the rotating axis 5 which is the target of detection, and a second arrangement which is an arrangement of N unit regions adjacent to the first arrangement, and is an arrangement of N unit regions for outputting correction information for correcting the position information. In this embodiment, M=9 and N=2. 【0054】 The first light-receiving member 48 receives LED light that has been irradiated from the irradiation unit 18 and passed through the first pattern 24, and outputs the intensity of the received light after binarizing it. For example, if the first light-receiving member 48 faces the first unit region 32 and receives sufficient light that has passed through the first unit region 32, the intensity of the received light will be above a predetermined threshold and "1" will be output. On the other hand, if the first light-receiving member 48 faces the second unit region 34 and does not receive sufficient light due to the second unit region 34, the intensity of the received light will be below a predetermined threshold and "0" will be output. 【0055】 As the rotating plate 12 rotates, the first light-receiving member 48 sequentially faces either the first unit region 32 or the second unit region 34, which are arranged in the circumferential direction, and each time it faces either the first unit region 32 or the second unit region 34, it binarizes the light-receiving intensity and outputs it. 【0056】 For example, by facing each unit region of the first arrangement, the first light-receiving member 48 outputs nine values. The leading edge of the first arrangement in the rotational direction is the first unit region 32, and the first light-receiving member 48 receives light that has been irradiated from the irradiation unit 18 and passed through the first unit region 32 by facing the first unit region 32. In the following description, the leading edge in the rotational direction will also simply be referred to as the leading edge. As shown in Figure 5(a), the intensity of the light received by the first light-receiving member 48 by facing the first unit region 32 becomes greater than or equal to a predetermined threshold, and the first light-receiving member 48 outputs "1". 【0057】 On the other hand, the second from the front of the first line unit region This is the second unit region 34, and when the first light-receiving member 48 faces the second unit region 34, it cannot sufficiently receive the light emitted from the irradiation unit 18. Therefore, the intensity of the light received by the first light-receiving member 48 by facing the second unit region 34 is smaller than a predetermined threshold, so the first light-receiving member 48 outputs "0". 【0058】 The nine output values ​​produced based on this first arrangement represent positional information indicating the position of the rotation axis 5, and the position of the rotation axis 5 can be determined by the combination of these nine output values. 【0059】 In this case, the fifth first unit region 32 from the beginning of the first sequence has foreign matter 7 attached to it that obstructs the transmission of light. When the first light receiving member 48 faces this first unit region 32, it cannot receive enough light, and the intensity of the received light becomes less than a predetermined threshold, resulting in the output of "0". In other words, in this case, the output value obtained based on the first unit region 32 is "0". 【0060】 The output values ​​generated based on the second sequence will be described later. 【0061】 As shown in Figure 4(b), in the second pattern 26, the first unit region 40 and the second unit region 42 are aligned in the direction of rotation. Hereinafter, the first unit region 40 and the second unit region 42 will also be simply referred to as unit regions. When the first unit region 40 and the second unit region 42 are referred to as unit regions, the second pattern 26 has a first arrangement which is an arrangement of M unit regions for outputting position information indicating the position of the rotation axis 5 which is the object to be detected, and a second arrangement which is an arrangement of N unit regions adjacent to the first arrangement, and is an arrangement of N unit regions for outputting correction information for correcting the position information. In this embodiment, M=9 and N=2. 【0062】 The second light-receiving member 50 receives LED light that has been irradiated from the irradiation unit 18 and passed through the second pattern 26, and outputs the intensity of the received light after binarizing it. For example, when the second light-receiving member 50 faces the first unit region 40 and receives light that has passed through the first unit region 40, the intensity of the received light becomes greater than or equal to a predetermined threshold and outputs "1". On the other hand, when the second light-receiving member 50 faces the second unit region 42 and is unable to receive enough light due to the second unit region 42, the intensity of the received light becomes less than a predetermined threshold and outputs "0". 【0063】 As the rotating plate 12 rotates, the second light-receiving member 50 sequentially faces either the first unit region 40 or the second unit region 42, which are arranged in the circumferential direction, and each time it faces either the first unit region 40 or the second unit region 42, it binarizes the light-receiving intensity and outputs it. 【0064】 For example, by facing each unit region of the first sequence, the second light-receiving member 50 outputs nine values. The first unit region of the first sequence is the second unit region 42, and when the second light-receiving member 50 faces the second unit region 42, it cannot sufficiently receive the light irradiated from the irradiation unit 18. As shown in Figure 5(b), the second unit region 42As a result of facing the second light-receiving member 50, the intensity of the light received by the second light-receiving member 50 is less than a predetermined threshold, so the second light-receiving member 50 outputs "0". 【0065】 On the other hand, the second from the front of the first line unit region The first unit region 40 is the first unit region 40, and when the second light-receiving member 50 faces the first unit region 40, it receives the light that has been irradiated from the irradiation unit 18 and passed through the first unit region 40. The intensity of the light received by the second light-receiving member 50 by facing the first unit region 40 is above a predetermined threshold, so the second light-receiving member 50 outputs "1". 【0066】 The order of the first arrangement in the second pattern 26 is reversed from the order of the first arrangement in the first pattern 24. Therefore, by reversing the output value of the second light-receiving member 50, which is output based on the first arrangement in the second pattern 26, it becomes the same as the output value of the first light-receiving member 48, which is output based on the first arrangement in the first pattern 24, and position information indicating the position of the rotation axis 5 is obtained. 【0067】 Furthermore, the order of the second arrangement in the second pattern 26 is reversed from the order of the second arrangement in the first pattern 24. Therefore, by reversing the output value of the second light-receiving member 50, which is output based on the second arrangement in the second pattern 26, it becomes the same as the output value of the first light-receiving member 48, which is output based on the second arrangement in the first pattern 24, and correction information for correcting position information is obtained. 【0068】 In this embodiment, inverting the output value means changing "1" to "0" and "0" to "1". 【0069】 As shown in Figure 4(c), the determination unit 52 determines whether the output value of the second light-receiving member 50 is the inverse of the output value of the first light-receiving member 48 by summing the output value of the first light-receiving member 48 with the output value of the second light-receiving member 50 corresponding to that output value. Specifically, the determination unit 52 sums the output value of the first light-receiving member 48 with the output value of the second light-receiving member 50 corresponding to that output value, and if the sum is "1", it determines that these output values ​​are inverses of each other and that these output values ​​are not incorrect. The determination unit 52 sums the output value of the first light-receiving member 48 with the output value of the second light-receiving member 50 corresponding to that output value, and if the sum is "0", it determines that these output values ​​are not inverses of each other and that one of these output values ​​is incorrect. 【0070】 For example, the output value "1" obtained based on the first unit region in the first sequence of the first pattern 24 corresponds to the output value "0" obtained based on the first unit region in the first sequence of the second pattern 26. When these corresponding output values ​​are added together, "1" + "0" = "1", and the total value is "1". Therefore, the determination unit 52 determines that these output values ​​are not incorrect. 【0071】 On the other hand, for example, the output value "0" obtained based on the fifth unit region from the beginning in the first sequence of the first pattern 24 corresponds to the output value "0" obtained based on the fifth unit region from the beginning in the first sequence of the second pattern 26. When these corresponding output values ​​are added together, "0" + "0" = "0", and the total value is "0". Therefore, the determination unit 52 determines that one of these output values ​​is incorrect. 【0072】 For example, if two patterns are provided in which the order of the first and second unit regions is the same, the output value based on the second unit region of one pattern and the corresponding second unit region of the other pattern will both be "0". Also, if foreign matter 7 adheres to both the first unit region of one pattern and the corresponding first unit region of the other pattern, the output value based on both of those first unit regions may also be "0". Thus, when two patterns are provided in which the order of the first and second unit regions is the same, it is impossible to distinguish whether the output value is based on the second unit region or on the first unit region to which the foreign matter is attached. Therefore, the system may not realize that the output value is incorrect and may mistakenly detect the position of the rotating shaft 5, resulting in a decrease in detection accuracy. 【0073】 In this embodiment, the output value of the first light-receiving member 48 and the output value of the second light-receiving member 50 corresponding to that output value are inverted. That is, (output value of the first light-receiving member 48, output value of the second light-receiving member 50 corresponding to that output value) = (1,0) or (0,1). Therefore, the sum of these output values ​​is, in principle, "1". As a result, if the sum is "1", the output value of the first light-receiving member 48 and the output value of the second light-receiving member 50 corresponding to that output value are correct, and if the sum is not "1", it is clear that one of these output values ​​is incorrect. In this way, it is possible to detect when an output value is incorrect, thus suppressing a decrease in detection accuracy. 【0074】 In the encoder described in Patent Document 1, if dust or other debris adheres to the pattern, light from the light source may be difficult to transmit or reflect due to the debris, potentially leading to false detections. Furthermore, detection accuracy may decrease if the false detection goes unnoticed. Even if a false detection is noticed, correcting the error is difficult, resulting in further detection accuracy reduction. 【0075】 In contrast, the encoder 10 in the embodiment can suppress a decrease in detection accuracy, as described above. 【0076】 Figure 6 is a diagram illustrating an example of the determination method and correction method by the correction unit 54 of the encoder 10 in Figure 1. Figure 6(a) illustrates the case where the output value output based on the first unit area of ​​the second sequence is used, and Figure 6(b) illustrates the case where the output value output based on the second unit area from the beginning of the second sequence is used. 【0077】 Figure 6(a) describes a method in which, when the determination unit 52 determines that either the output value output based on the third unit region from the beginning of the first sequence of the first pattern 24 or the output value output based on the third unit region from the beginning of the first sequence of the second pattern 26 is incorrect, the determination unit 52 determines whether the output value output based on the unit region of the first pattern 24 is correct or incorrect, and corrects the output value if it is incorrect. 【0078】 As shown in Figure 6(a), the correction unit 54 acquires two output values ​​based on a second sequence, in addition to the nine output values ​​output based on the first sequence. The two output values ​​output based on the second sequence are output values ​​output from the first light receiving member 48, similar to the nine output values ​​output based on the first sequence. The two output values ​​output based on the second sequence are correction information for correcting at least one of the nine output values, which are position information indicating the position of the rotation axis 5. 【0079】 In this embodiment, the output value output based on the first unit area of ​​the second sequence is information for determining whether one output value, which has been determined by the determination unit 52 to be potentially incorrect, is incorrect among the output values ​​output based on the first, third from the top, fifth from the top, sixth from the top, seventh from the top, and eighth from the top unit areas of the first sequence, and if that one output value is incorrect, it is information for correcting that one output value. 【0080】 When the first value is obtained by taking the exclusive OR of the output values ​​output based on the first and third unit areas from the first in the first sequence, the second value is obtained by taking the exclusive OR of the first value and the output values ​​output based on the fifth unit area from the first, the third value is obtained by taking the exclusive OR of the second value and the output values ​​output based on the sixth unit area from the first, the fourth value is obtained by taking the exclusive OR of the third value and the output values ​​output based on the seventh unit area from the first, and the fifth value is obtained by taking the exclusive OR of the fourth value and the output values ​​output based on the eighth unit area from the first, the output value obtained based on the first unit area of ​​the second sequence will be equal to the fifth value. 【0081】 For example, if the output value based on the first unit area of ​​the second sequence is "0", then the sum of the output values ​​based on the first, third, fifth, sixth, seventh, and eighth unit areas of the first sequence will be an even number. 【0082】 On the other hand, if the output value output based on the first unit area of ​​the second sequence is "1", then the sum of the output values ​​output based on the first, third, fifth, sixth, seventh, and eighth unit areas of the first sequence will be an odd number. 【0083】 In Figure 6(a), the output value obtained based on the first unit region of the second sequence is "0". Also, the sum of the output values ​​output based on the first, third, fifth, sixth, seventh, and eighth unit regions of the first sequence is "0" + "0" + "1" + "1" + "0" + "1" = "3", which is an odd number. Therefore, it can be seen that one of the output values ​​output based on the first, third, fifth, sixth, seventh, and eighth unit regions of the first sequence is incorrect. 【0084】 As described above, it is determined here that either the output value output based on the third unit area from the beginning of the first sequence of the first pattern 24, or the output value output based on the third unit area from the beginning of the first sequence of the second pattern 26, is incorrect. Therefore, the correction unit 54 determines that the output value obtained based on the third unit area from the beginning is incorrect among the output values ​​output based on the first, third, fifth, sixth, seventh, and eighth unit areas from the beginning of the first sequence of the first pattern 24, and corrects the output value from "0" to "1" before outputting it. 【0085】 Figure 6(b) describes a method in which, when the determination unit 52 determines that either the output value output based on the fourth unit region from the beginning of the first sequence of the first pattern 24 or the output value output based on the fourth unit region from the beginning of the first sequence of the second pattern 26 is incorrect, the determination unit 52 determines whether the output value output based on the unit region of the first pattern 24 is correct or incorrect, and corrects the output value if it is incorrect. 【0086】 As shown in Figure 6(b), the correction unit 54 acquires two output values ​​based on the second sequence, in addition to the nine output values ​​obtained based on the first sequence, similar to the case shown in Figure 6(a). 【0087】 In this embodiment, the output value output based on the second unit region from the beginning of the second sequence is information for determining whether one of the output values ​​output based on the second, fourth, sixth, seventh, eighth, and ninth elements from the beginning of the first sequence, which the determination unit 52 has determined to be potentially incorrect, is incorrect, and is information for correcting that one value if it is incorrect. 【0088】 If we define the sixth value as the exclusive OR of the output values ​​output based on the second and fourth unit areas from the beginning of the first sequence, the seventh value as the exclusive OR of the sixth value and the output values ​​output based on the sixth unit area from the beginning, the eighth value as the exclusive OR of the seventh value and the output values ​​output based on the seventh unit area from the beginning, the ninth value as the exclusive OR of the eighth value and the output values ​​output based on the eighth unit area from the beginning, and the tenth value as the exclusive OR of the ninth value and the output values ​​output based on the ninth unit area from the beginning, then the output value output based on the second unit area from the beginning of the second sequence will be equal to the tenth value. 【0089】 For example, if the output value obtained based on the second unit region from the top of the second sequence is "0", then the sum of the output values ​​obtained based on the second, fourth, sixth, seventh, eighth, and ninth unit regions from the top of the first sequence will be an even number. 【0090】 On the other hand, if the output value obtained based on the second unit region from the beginning of the second sequence is "1", then the sum of the output values ​​obtained based on the second, fourth, sixth, seventh, eighth, and ninth unit regions from the beginning of the first sequence will be an odd number. 【0091】 In Figure 6(b), the output value output based on the second unit area from the beginning of the second sequence is "0". Also, the sum of the output values ​​output based on the second, fourth, sixth, seventh, eighth, and ninth unit areas from the beginning of the first sequence is "1" + "0" + "0" + "0" + "0" + "1" = "2", which is an even number. Therefore, the correction unit 54 determines that the output value output based on the fourth unit area from the beginning of the first sequence of the first pattern 24 is not incorrect and outputs "0" without correcting the output value. 【0092】 Furthermore, by inverting the output values ​​that are generated based on the first and second sequences of the second pattern 26, the same processing as described above can be performed. 【0093】 Figure 7 shows a calculation circuit 56 that calculates values ​​for forming the first pattern 24 on the rotating plate 12 of the encoder 10 in Figure 1. Figure 8 is a table showing the values ​​obtained by the calculation circuit 56 in Figure 7. 【0094】 The calculation circuit 56 shown in Figure 7 is an M code (irreducible polynomial): X 9 +X 7 +X 5 +X 4 +X 3 +X 2 +1 This is a circuit for calculating values ​​based on [the given information]. By forming the first pattern 24 based on the values ​​obtained by the calculation circuit 56, the first pattern 24 having a first arrangement and a second arrangement can be formed. 【0095】 As shown in Figure 7, the calculation circuit 56 has a plurality of registers 58 to 74 and a plurality of XOR circuits 76 to 86. 【0096】 Each of the multiple registers 58 to 74 stores a value used in calculations performed by the calculation circuit 56, and each of the multiple registers 58 to 74 outputs the value it has stored. 【0097】 The value output from register 60 is input to register 58. The value output from register 62 is input to XOR circuit 76 and register 60. The value output from register 64 is input to register 62. The value output from register 66 is input to XOR circuit 78 and register 64. The value output from register 68 is input to XOR circuit 80 and register 66. The value output from register 70 is input to XOR circuit 82 and register 68. The value output from register 72 is input to XOR circuit 84 and register 70. The value output from register 74 is input to register 72. 【0098】 Each of the XOR circuits 76-86 calculates the exclusive OR of two input values ​​and outputs the calculated value. XOR circuit 76 receives the values ​​output from register 58 and register 62 as inputs, calculates the exclusive OR of these two values, and outputs the calculated value. XOR circuit 78 receives the values ​​output from register 66 and XOR circuit 76 as inputs, calculates the exclusive OR of these two values, and outputs the calculated value. XOR circuit 80 receives the values ​​output from register 68 and XOR circuit 78 as inputs, calculates the exclusive OR of these two values, and outputs the calculated value. XOR circuit 82 receives the value output from register 70 and the value output from XOR circuit 80 as inputs. XOR circuit 82 calculates the exclusive OR of these two values ​​and outputs the calculated value. XOR circuit 84 receives the value output from register 72 and the value output from XOR circuit 82 as inputs. XOR circuit 84 calculates the exclusive OR of these two values ​​and outputs the calculated value. XOR circuit 86 receives a predetermined value input from an external source and the value output from XOR circuit 84 as inputs. XOR circuit 86 calculates the exclusive OR of these two values ​​and outputs the calculated value. For example, the predetermined value is a single value determined in advance. The value output from XOR circuit 86 is input to register 74. 【0099】 Each of the multiple registers 58-74 outputs the input value each time a new value is input. Each of the multiple XOR circuits 76-86 calculates and outputs the exclusive OR of the two input values ​​each time two new values ​​are input. 【0100】 This section describes the case where registers 58, 60, 64, 70, and 74 are pre-stored with "0", and registers 62, 66, 68, and 72 are pre-stored with "1". 【0101】 In this case, first, registers 58, 60, 64, 70, and 74 output "0", and registers 62, 66, 68, and 72 output "1". 【0102】 XOR circuit 76 outputs "1", which is the exclusive OR of "0" and "1". XOR circuit 78 outputs "0", which is the exclusive OR of "1" and "1". XOR circuit 80 outputs "1", which is the exclusive OR of "1" and "0". XOR circuit 82 outputs "1", which is the exclusive OR of "0" and "1". XOR circuit 84 outputs "0", which is the exclusive OR of "1" and "1". When "0" is input to XOR circuit 86 from the outside, XOR circuit 86 outputs "0", which is the exclusive OR of "0" and "0". 【0103】 As described above, each of the registers 58-74 outputs the input value each time a new value is input. Each of the XOR circuits 76-86 calculates and outputs the exclusive OR of the two input values ​​each time two new values ​​are input. By repeatedly calculating and outputting the exclusive OR in this way, the values ​​shown in Figure 8 are obtained. 【0104】 As shown in Figure 8, the nine output values ​​from the multiple registers 58 to 74 are the values ​​that form the first sequence. For example, looking at the top row of the output values ​​in the table shown in Figure 8, the nine output values ​​from the multiple registers 58 to 74 are "001011010". In this case, the first sequence can be formed by arranging the second unit area 34, second unit area 34, first unit area 32, second unit area 34, first unit area 32, first unit area 32, second unit area 34, first unit area 32, and second unit area 34 in this order in the circumferential direction. 【0105】 The value output from register 60 is then output from register 58, the value output from register 62 is then output from register 60, the value output from register 64 is then output from register 62, the value output from register 66 is then output from register 64, and the value output from register 68 is then output from register 66. Similarly, the value output from register 70 is then output from register 68, the value output from register 72 is then output from register 70, the value output from register 74 is then output from register 72, the value output from XOR circuit 86 is then output from register 74, and XOR circuit 86 calculates and outputs a new value based on these values. This process is repeated. 【0106】 The nine output values ​​from the multiple registers 58-74 are, as described above, the values ​​that form the first sequence. The value output from the XOR circuit 86 along with these nine output values, and the value output from the XOR circuit 86 after that value, are the values ​​that form the second sequence, which corresponds to the first sequence formed based on these nine output values. 【0107】 Multiple registers 58-74 and an XOR circuit 86 repeatedly output values, allowing multiple values ​​to be obtained to form a first sequence, and thus multiple first sequences to be formed. In other words, the first pattern 24 formed using the values ​​shown in Figure 8 has multiple first sequences. The multiple first sequences in the first pattern 24 are formed continuously with each unit region shifted by one. That is, the sequence of nine unit regions in the first pattern 24 is a first sequence, and the sequence of nine units shifted by one in the circumferential direction from the sequence of nine unit regions is also a first sequence. The order in which the first unit region 32 and the second unit region 34 are arranged differs from one another in the multiple first sequences. In other words, the multiple first sequences are formed such that the sequence of nine output values ​​obtained based on each of the multiple first sequences is not the same. 【0108】 Furthermore, by repeatedly outputting values ​​using multiple registers 58-74 and the XOR circuit 86, multiple values ​​for forming a second sequence can be obtained, and multiple second sequences can be formed. In other words, the first pattern 24 formed using the values ​​shown in Figure 8 has multiple second sequences. Each of the multiple second sequences in the first pattern 24 corresponds to one of the multiple first sequences described above, and each of the multiple second sequences is a sequence of two unit regions adjacent to the corresponding first sequence. Each of the multiple second sequences is a sequence for outputting correction information to correct the output value output based on the corresponding first sequence. The multiple second sequences in the first pattern 24 are formed continuously with each unit region shifted by one. In other words, a sequence of two unit regions in the first pattern 24 is a second sequence, and two sequences with each unit region shifted by one in the circumferential direction relative to the two sequences of unit regions are also second sequences. 【0109】 Figure 9 shows the data flow during the operation of the correction unit 54 of the encoder 10 in Figure 1. In Figure 9, in the first and second sequences, "1" indicates the first unit area 32, and "0" indicates the second unit area 34. Figure 9 explains the case where foreign matter 7 is attached to the third unit area from the beginning of the first sequence of the first pattern 24. 【0110】 As shown in Figure 9, the determination unit 52 uses the nine output values ​​output by the first light-receiving member 48 and the nine output values ​​output by the second light-receiving member 50 to determine whether or not there are errors in these output values. The determination method used by the determination unit 52 is omitted here, as it can be found in the explanation above. The determination unit 52 transmits error location information indicating potentially incorrect output values ​​to the correction unit 54. 【0111】 The correction unit 54 recognizes, based on the error location information, the output values ​​of the first light receiving member 48 output based on the first sequence that may be incorrect. Here, the error location information indicates that the output value output based on the third unit region from the beginning may be incorrect. 【0112】 The correction unit 54 performs an error determination on potentially incorrect output values ​​to determine whether or not they are incorrect. Specifically, the correction unit 54 determines whether or not an potentially incorrect output value from the output values ​​of the first light receiving member 48 is incorrect using output values ​​other than the output value in question. The method of determination by the correction unit 54 is omitted here, as it can be found in the explanation above. 【0113】 If the output value of the first light-receiving member 48 is incorrect, the correction unit 54 performs a correction operation on the pre-correction data to calculate the corrected data. The corrected data is the value obtained by correcting the output value of the first light-receiving member 48. The correction method by the correction unit 54 is omitted here, as it can be found in the explanation above. 【0114】 After calculating the corrected data, the correction unit 54 performs a scan to determine whether there are any other incorrect output values ​​among the output values ​​of the first light receiving member 48. 【0115】 The correction unit 54 corrects all correctable output values ​​and then selects to output either raw data or corrected data to the outside. Raw data is the same value as the output value of the first light-receiving member 48. For incorrect output values, the correction unit 54 outputs corrected data. 【0116】 Figure 10 is a diagram illustrating another example of the correction method by the correction unit 54 of the encoder 10 in Figure 1. Figure 10(a) illustrates the correction of one of the output values ​​of the first light receiving member 48, and Figure 10(b) illustrates the correction of another of the output values ​​of the first light receiving member 48. Referring to Figure 10, the case in which two of the output values ​​of the first light receiving member 48 are corrected will be explained. 【0117】 As shown in Figure 10(a), the correction unit 54 acquires two output values ​​(correction information) based on the second sequence, in addition to the nine output values ​​(position information) output based on the first sequence. 【0118】 The output value obtained based on the first unit area of ​​the second sequence is "0". Also, the sum of the output values ​​output based on the first, fifth, sixth, seventh, and eighth unit areas of the first sequence is "0" + "1" + "1" + "0" + "1" = "3", which is an odd number. Therefore, in order to make the sum an even number, the correction unit 54 outputs the output value output based on the third unit area of ​​the first sequence as "1". 【0119】 Next, as shown in Figure 10(b), the correction unit 54 corrects the output value that is output based on the second unit region from the beginning of the first sequence. 【0120】 The output value output based on the second unit area from the beginning of the second sequence is "0". Also, the sum of the output values ​​output based on the fourth, sixth, seventh, eighth, and ninth unit areas from the beginning of the first sequence is "0" + "1" + "0" + "1" + "0" = "2", which is an even number. Therefore, in order to maintain the sum as an even number, the correction unit 54 outputs the output value output based on the second unit area from the beginning of the first sequence as "0". 【0121】 Figure 11 is a diagram illustrating another example of the correction method by the correction unit 54 of the encoder 10 in Figure 1. Figure 11(a) illustrates the correction of one of the output values ​​of the first light receiving member 48, and Figure 11(b) illustrates the correction of another of the output values ​​of the first light receiving member 48. Referring to Figure 11, the case in which two of the output values ​​of the first light receiving member 48 are corrected will be explained. 【0122】 As shown in Figure 11(a), the output value obtained based on the second unit region from the beginning of the second sequence is "0". Also, the sum of the output values ​​output based on the second, fourth, seventh, eighth, and ninth unit regions from the beginning of the first sequence is "0" + "0" + "0" + "1" + "0" = "1", which is an odd number. Therefore, in order to make the sum an even number, the correction unit 54 outputs the output value output based on the sixth unit region from the beginning of the first sequence as "1". 【0123】 Next, as shown in Figure 11(b), the correction unit 54 corrects the output value that is output based on the fifth unit region from the beginning of the first sequence using the corrected value. 【0124】 The output value output based on the first unit area of ​​the second sequence is "0". Also, the sum of the output values ​​output based on the first, third, sixth, seventh, and eighth unit areas of the first sequence is "0" + "1" + "1" + "0" + "1" = "3", which is an odd number. Therefore, in order to make the sum an even number, the correction unit 54 outputs the output value output based on the fifth unit area of ​​the first sequence as "1". 【0125】 Figure 12 illustrates yet another example of the correction method by the correction unit 54 of the encoder 10 in Figure 1. Figure 12(a) illustrates the correction of one of the output values ​​of the first light receiving member 48, and Figure 12(b) illustrates the correction of another of the output values ​​of the first light receiving member 48. Referring to Figure 12, the case in which two of the output values ​​of the first light receiving member 48 are corrected will be explained. 【0126】 As shown in Figure 12(a), the output value obtained based on the first unit area of ​​the second sequence is "0". Also, the sum of the output values ​​output based on the first, third, fifth, sixth, and seventh unit areas of the first sequence is "0" + "1" + "1" + "1" + "0" = "3", which is an odd number. Therefore, in order to make the sum an even number, the correction unit 54 outputs the output value output based on the eighth unit area of ​​the first sequence as "1". 【0127】 Next, as shown in Figure 12(b), the correction unit 54 corrects the output value that is output based on the fourth unit region from the beginning of the first sequence using the corrected value. 【0128】 The output value output based on the second unit area from the beginning of the second sequence is "0". Also, the sum of the output values ​​output based on the second, sixth, seventh, eighth, and ninth unit areas from the beginning of the first sequence is "0" + "1" + "0" + "1" + "0" = "2", which is an even number. Therefore, in order to maintain the sum as an even number, the correction unit 54 outputs the output value output based on the fourth unit area from the beginning of the first sequence as "0". 【0129】 In this way, the correction unit 54 can further correct other output values ​​using the corrected output value. 【0130】 The encoder 10 according to the embodiment has been described above. 【0131】 The encoder 10 according to this embodiment includes a rotating plate 12 having a first pattern 24 and a second pattern 26, an illumination unit 18 that illuminates the first pattern 24 and the second pattern 26 with light, and a light receiving unit 20 that receives light illuminated from the illumination unit 18 and passing through the first pattern 24 and light illuminated from the illumination unit 18 and passing through the second pattern 26, wherein the first pattern 24 includes a first unit region 32 that guides the light illuminated from the illumination unit 18 to the light receiving unit 20 and a second unit region that does not guide the light illuminated from the illumination unit 18 to the light receiving unit 20. The first pattern 24 has a configuration in which the first unit region 32 and the second unit region 34 are arranged in the circumferential direction centered on the rotation axis A of the rotating plate 12. The second pattern 26 has a configuration in which the first unit region 40 that guides the light emitted from the irradiation unit 18 to the light receiving unit 20 and the second unit region 42 that does not guide the light emitted from the irradiation unit 18 to the light receiving unit 20 are arranged in the circumferential direction centered on the rotation axis A of the rotating plate 12. The order in which the first unit region 32 and the second unit region 34 are arranged in the first pattern 24 is reversed from the order in which the first unit region 40 and the second unit region 42 are arranged in the second pattern 26. 【0132】 According to this, the light guided from the first pattern 24 and the light guided from the second pattern 26 can be reversed. Specifically, when the first pattern 24 guides light to the light receiving unit 20, the second pattern 26 does not guide light to the light receiving unit 20, and when the first pattern 24 does not guide light to the light receiving unit 20, the second pattern 26 guides light to the light receiving unit 20. Therefore, if light is not guided to the light receiving unit 20 from both the first pattern 24 and the second pattern 26, it is possible to notice that some kind of abnormality has occurred. For example, if foreign matter 7 is attached to both the first pattern 24 and the second pattern 26, and light is not guided to the light receiving unit 20 from both the first pattern 24 and the second pattern 26, it is possible to notice that some kind of abnormality has occurred. In this way, by noticing the occurrence of an abnormality, the occurrence of false detections can be suppressed and the decrease in detection accuracy can be suppressed. 【0133】 Furthermore, the encoder 10 according to the embodiment further comprises a determination unit 52, and the light receiving unit 20 has a first light receiving member 48 that receives light irradiated from the irradiation unit 18 and passes through the first pattern 24, and outputs the intensity of the received light after binarizing it, and a second light receiving member 50 that receives light irradiated from the irradiation unit 18 and passes through the second pattern 26, and outputs the intensity of the received light after binarizing it, and the second pattern 26 is provided so that the output value of the second light receiving member 50 is the inverse of the output value of the first light receiving member 48, and the determination unit 52 determines that either the output value of the first light receiving member 48 or the output value of the second light receiving member 50 is incorrect if the output value of the second light receiving member 50 is not the inverse of the output value of the first light receiving member 48, and outputs the determination result. 【0134】 According to this, the output value of the first light-receiving member 48 based on light that has passed through the first pattern 24 and the output value of the second light-receiving member 50 based on light that has passed through the second pattern 26 can be inverted. If these output values ​​are not inverted, the determination unit 52 determines that one of these output values ​​is incorrect. Therefore, it is easy to notice when an output value is incorrect, and the occurrence of false detections can be further suppressed, thus further suppressing the decrease in detection accuracy. 【0135】 Furthermore, the first pattern 24 includes, when the first unit region 32 and the second unit region 34 are called unit regions, a first arrangement which is an arrangement of nine unit regions for outputting position information indicating the position of the rotation axis 5, and a second arrangement which is an arrangement of two unit regions adjacent to the first arrangement, and is an arrangement of two unit regions for outputting correction information for correcting the position information. 【0136】 According to this, the first pattern 24 has a second arrangement which is an arrangement of two unit regions for outputting correction information to correct the position information. Therefore, if the first arrangement fails to properly guide the light from the illumination unit 18 to the light receiving unit 20 and the position information is incorrect, the position information can be corrected using the correction information, thereby suppressing a decrease in detection accuracy. 【0137】 Furthermore, the first pattern 24 has a plurality of first sequences and a plurality of second sequences corresponding to each of the plurality of first sequences. 【0138】 According to this method, correction information is obtained for each of the multiple location information points obtained based on the multiple first sequences. Therefore, even if any of the multiple location information points is incorrect, it can be corrected using the corresponding correction information, thereby suppressing a decrease in detection accuracy. 【0139】 Next, we will describe another example of the correction method using the correction unit 54. 【0140】 Figure 13 shows another example of the light intensity received by the light receiving section 20 of the encoder 10 in Figure 1. Figure 13(a) shows another example of the light intensity received by the first light receiving member 48, and Figure 13(b) shows another example of the light intensity received by the second light receiving member 50. 【0141】 The above description describes a case in which the correction unit 54 corrects errors in the output values ​​output based on the first sequence using the output values ​​output based on the second sequence, but it is not limited to this. For example, the correction unit 54 may acquire the light reception intensity of the light received by the first light receiving member 48 and the light reception intensity of the light received by the second light receiving member 50, and use these to correct errors in the output values ​​obtained based on the first sequence. 【0142】 This section describes the case where both the output value output based on the fifth unit region from the beginning of the first sequence in the first pattern 24, and the output value output based on the fifth unit region from the beginning of the first sequence in the second pattern 26, are "0", and the determination unit 52 determines that either of these output values ​​is incorrect. 【0143】 In this case, as shown in Figure 13, the correction unit 54 obtains the light reception intensity of the light received by the first light receiving member 48 based on the fifth unit region from the beginning of the first sequence of the first pattern 24, and the light reception intensity of the light received by the second light receiving member 50 based on the fifth unit region from the beginning of the first sequence of the second pattern 26. The correction unit 54 then compares these obtained light reception intensities and corrects the error in the output value based on the comparison result. Specifically, the light reception intensity of the light received by the first light receiving member 48 is greater than the light reception intensity of the light received by the second light receiving member 50. Therefore, the correction unit 54 corrects the output value of the first light receiving member 48 to "1" and outputs it, while leaving the output value of the second light receiving member 50 as "0". 【0144】 Next, we will describe the calculation circuit 88 that calculates a value to form a first pattern different from the first pattern 24 of the encoder 10. 【0145】 Figure 14 shows a calculation circuit 88 that calculates values ​​to form a first pattern different from the first pattern 24 of the encoder 10 in Figure 1. Figure 15 is a table showing the values ​​obtained by the calculation circuit 88 in Figure 14. 【0146】 The calculation circuit 88 shown in Figure 14 is an M code (irreducible polynomial): X 9 +X 5 +1 This is a circuit for calculating values ​​based on [the given information]. By forming a first pattern based on the values ​​obtained by the calculation circuit 88, a first pattern having a first arrangement and a second arrangement different from the first pattern 24 can be formed. 【0147】 As shown in Figure 14, the calculation circuit 88 has multiple registers 90 to 106 and multiple XOR circuits 108 and 110. 【0148】 The value output from register 90 is input to XOR circuit 108. The value output from register 92 is input to register 90. The value output from register 94 is input to register 92. The value output from register 96 is input to register 94. The value output from register 98 is input to XOR circuit 108 and register 96. The value output from register 100 is input to register 98. The value output from register 102 is input to register 100. The value output from register 104 is input to register 102. The value output from register 106 is input to register 104. 【0149】 The XOR circuit 108 receives the value output from register 90 and the value output from register 98 as inputs. The XOR circuit 108 calculates the exclusive OR of these two values ​​and outputs the calculated value. The XOR circuit 110 receives a predetermined value input from an external source and the value output from XOR circuit 108 as inputs. The XOR circuit 110 calculates the exclusive OR of these two values ​​and outputs the calculated value. For example, the predetermined value is a single value determined in advance. The value output from XOR circuit 110 is input to register 106. 【0150】 For example, if registers 90, 94, 98, and 102 are pre-stored with "0", and registers 92, 96, 100, 104, and 106 are pre-stored with "1", the values ​​shown in Figure 15 can be obtained by repeatedly calculating and outputting the exclusive OR operation. 【0151】 By using the values ​​shown in Figure 15, a first pattern can be formed which has a first arrangement of nine unit regions, a second arrangement of four unit regions, and a third arrangement of one unit region for outputting correction information to correct the position information obtained based on the first arrangement. The third arrangement is adjacent to the first arrangement on the opposite side from the second arrangement. 【0152】 For example, the output value based on the first unit area of ​​the second sequence is the exclusive OR of the two output values ​​based on the first and fifth unit areas of the first sequence. Similarly, the output value based on the fourth unit area of ​​the second sequence is the exclusive OR of the two output values ​​based on the fourth and eighth unit areas of the first sequence. Furthermore, the output value based on the ninth unit area of ​​the first sequence is the exclusive OR of the two output values ​​based on the first unit area of ​​the third sequence and the fourth unit area of ​​the first sequence. Because of these relationships, the position information obtained based on the first sequence can be corrected using the correction information obtained based on the second sequence and the correction information obtained based on the third sequence. 【0153】 (Other embodiments, etc.) As described above, embodiments have been explained as examples of the technology disclosed in this application. However, the technology disclosed herein is not limited to these embodiments, and can be applied to embodiments or modified versions that are changed, replaced, added, omitted, etc., as appropriate, as long as they do not deviate from the spirit of this disclosure. 【0154】 In the embodiments described above, the encoder 10 is described as having a first pattern 24 and a second pattern 26, but it is not limited to this. For example, the encoder 10 does not have to have a second pattern 26. 【0155】 In this case, the encoder comprises a rotating plate 12 having a first pattern 24, an illumination unit 18 that illuminates the first pattern 24 with light, and a light receiving unit 20 that receives the light illuminated from the illumination unit 18 and passed through the first pattern 24. The first pattern 24 has a configuration in which a first unit region 32 that guides the light illuminated from the illumination unit 18 to the light receiving unit 20 and a second unit region 34 that does not guide the light illuminated from the illumination unit 18 to the light receiving unit 20 are arranged in the circumferential direction centered on the rotation axis A of the rotating plate 12. When the first unit region 32 and the second unit region 34 are called unit regions, there is a first arrangement which is an arrangement of nine unit regions for outputting position information indicating the position of the rotation axis 5, and a second arrangement which is an arrangement of two unit regions adjacent to the first arrangement which is an arrangement of two unit regions for outputting correction information for correcting the position information. 【0156】 According to this, the first pattern 24 has a second arrangement which is an arrangement of two unit regions for outputting correction information to correct the position information. Therefore, if the first arrangement fails to properly guide the light from the illumination unit 18 to the light receiving unit 20 and the position information is incorrect, the position information can be corrected using the correction information, thereby suppressing a decrease in detection accuracy. 【0157】 Furthermore, although the above-described embodiment described the case where the object detected by the encoder 10 is the rotating shaft 5, the invention is not limited to this. For example, the object detected by the encoder 10 does not have to be the rotating shaft 5, but any rotating body. 【0158】 Furthermore, although the above-described embodiment described a case in which the first unit region 32 and the first unit region 40 transmit light emitted from the irradiation unit 18 and guide it to the light receiving unit 20, the invention is not limited to this. For example, the first unit region may reflect light emitted from the irradiation unit and guide it to the light receiving unit. In this case, for example, the body of the rotating plate may be made of SUS or the like, the first unit region may be made of chrome plating or the like that which reflects light, and the second unit region may be made of black chrome plating or the like that which does not reflect light. 【0159】 Furthermore, although the above-described embodiment described a case in which the second pattern 26 is provided radially inward from the first pattern 24, the invention is not limited to this. For example, the second pattern may be provided radially outward from the first pattern. 【0160】 Furthermore, although the above-described embodiment described a case in which the first unit region 32 and the second unit region 42 corresponding to the first unit region 32 are adjacent in the radial direction, the embodiment is not limited to this. For example, the first unit region 32 and the second unit region 42 corresponding to the first unit region 32 do not have to be adjacent in the radial direction, and may be provided at positions offset in the radial direction. 【0161】 Furthermore, although the above-described embodiment described a case in which the second unit region 34 and the first unit region 40 corresponding to the second unit region 34 are adjacent in the radial direction, the invention is not limited to this. For example, the second unit region 34 and the first unit region 40 corresponding to the second unit region 34 do not have to be adjacent in the radial direction, and may be provided at positions offset in the radial direction. 【0162】 Furthermore, although the above-described embodiment described a case in which the first pattern 24 and the second pattern 26 are provided on the main surface of the main body 22 on the side of the first substrate 14, the invention is not limited to this. For example, the main body of the rotating plate may be made of a material that does not transmit light, and the first unit region may be formed by a through hole that penetrates the main body of the rotating plate, thereby forming the first and second patterns. In this case, a part of the main body of the rotating plate becomes the second unit region. 【0163】 Furthermore, although the above-described embodiment described a case in which the first arrangement is an arrangement of nine unit regions, the second arrangement is an arrangement of two or four unit regions, and the third arrangement is an arrangement of one unit region, the embodiment is not limited to this. [Industrial applicability] 【0164】 The encoder described herein can be used for detecting the rotation of the rotating shaft of a motor that rotates a load. [Explanation of Symbols] 【0165】 10 encoders 12 Rotating Plates 14. First circuit board 16. Second board 18 Irradiation area 20 Light receiving part 22 Main unit 24 Pattern 1 26. Pattern 2 28 1st light guide section 30 First non-light guide section 32,40 First Unit Area 34,42 Second Unit Area 36 Second light guiding section 38 Second non-light guide section 44 First light-emitting section 46 Second light-emitting section 48 First light-receiving member 50 Second light-receiving member 52 Judgment section 54 Correction Section

Claims

[Claim 1] It is configured to rotate in the rotational direction about a rotation axis, and comprises a rotating plate having a first pattern and a second pattern, An illumination unit that irradiates the first pattern and the second pattern with light, A light receiving unit that receives light irradiated from the irradiating unit and that has passed through the first pattern, and light irradiated from the irradiating unit and that has passed through the second pattern, The determination unit, Equipped with, The first and second patterns have a configuration in which a first unit region that guides light emitted from the irradiation unit to the light receiving unit and a second unit region that does not guide light emitted from the irradiation unit to the light receiving unit are arranged in the circumferential direction centered on the rotation axis of the rotating plate. The first unit region and the second unit region in the first pattern are arranged so as to be reversed in a direction perpendicular to the rotation direction with respect to the first unit region and the second unit region in the second pattern. The light receiving unit includes a first light receiving member that receives light irradiated from the irradiation unit and passes through the first pattern, and outputs the intensity of the received light after binarizing it, and a second light receiving member that receives light irradiated from the irradiation unit and passes through the second pattern, and outputs the intensity of the received light after binarizing it. The second pattern is provided such that the output value of the second light-receiving member is the inverse of the output value of the first light-receiving member. The determination unit determines that if the output value of the second light-receiving member is not the inverse of the output value of the first light-receiving member, then either the output value of the first light-receiving member or the output value of the second light-receiving member is incorrect, and outputs the determination result. Encoder. [Claim 2] Further includes a correction section, The first pattern is, When the first unit region and the second unit region are referred to as unit regions, A first arrangement is an arrangement of M unit regions for outputting position information indicating the position of the unit region to be detected, The first arrangement and the second arrangement which is an arrangement of N adjacent unit regions, It has, The correction unit is configured to correct the position information based on the second arrangement when the determination unit determines that either the output value of the first light-receiving member or the output value of the second light-receiving member is incorrect. The encoder according to claim 1. [Claim 3] The first pattern is, When the first unit region and the second unit region are referred to as unit regions, A first arrangement is an arrangement of M unit regions for outputting position information indicating the position of the unit region to be detected, A second arrangement of N unit regions adjacent to the first arrangement, which is an arrangement of N unit regions for outputting correction information for correcting the position information, Having, The encoder according to claim 1. [Claim 4] The first pattern comprises a plurality of the first arrangements and a plurality of the second arrangements corresponding to each of the plurality of the first arrangements. The encoder according to claim 2 or 3.

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