Encoder

Abstract

The encoder includes: a rotating plate having a first pattern and a second pattern; an irradiation unit that irradiates light; and a light receiving unit that receives light, wherein the first pattern has a structure in which a first unit region and a second unit region are arranged along the circumferential direction centered on the rotation axis of the rotating plate, the first unit region guides the light irradiated from the irradiation unit to the light receiving unit, the second unit region does not guide the light irradiated from the irradiation unit to the light receiving unit, the second pattern has a structure in which a first unit region and a second unit region are arranged along the circumferential direction centered on the rotation axis of the rotating plate, the first unit region guides the light irradiated from the irradiation unit to the light receiving unit, the second unit region does not guide the light irradiated from the irradiation unit to the light receiving unit, and the first unit region and the second unit region in the first pattern are arranged in a direction perpendicular to the rotation direction of the rotating plate and opposite to the first unit region and the second unit region in the second pattern.

Description

Technical Field

[0001] The present disclosure relates to an encoder. Background Art

[0002] Conventionally, an encoder for detecting the rotation of a rotating shaft of a motor has been known. For example, Patent Document 1 discloses an encoder having: a pattern along a measurement direction; a light source that emits light toward the pattern; and a plurality of light receiving elements configured to be arranged along the measurement direction, the light receiving elements being for receiving light emitted from the light source and transmitted through or reflected by the pattern.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2016-118486 Summary of the Invention

[0006] 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 light to the first pattern and the second pattern; and a light receiving unit that receives light irradiated from the irradiation unit and passing through the first pattern and light irradiated from the irradiation unit and passing through the second pattern, wherein the first pattern and the second pattern have a structure in which a first unit region and a second unit region are arranged in a circumferential direction centered on the rotation axis of the rotating plate, the first unit region guides the light emitted from the irradiation unit to the light receiving unit, the second unit region does not guide the light emitted from the irradiation unit to the light receiving unit, and the order of arrangement of the first unit region and the second unit region in the first pattern is opposite to the order of arrangement of the first unit region and the second unit region in the second pattern.

[0007] In addition, an encoder according to one aspect of the present disclosure includes: a rotating plate having a pattern; an irradiation unit that irradiates light onto the pattern; and a light receiving unit that receives light irradiated from the irradiation unit and passing through the pattern. The pattern has a structure in which a first unit region and a second unit region are arranged along the circumferential direction centered on the rotation axis of the rotating plate. The first unit region guides the light irradiated from the irradiation unit to the light receiving unit, and the second unit region does not guide the light irradiated from the irradiation unit to the light receiving unit. When the first unit region and the second unit region are referred to as unit regions, the pattern has: a first arrangement that is an arrangement of M of the unit regions and is used to output position information indicating the position of a detection object; and a second arrangement that is an arrangement of N of the unit regions adjacent to the first arrangement and is used to output correction information for correcting the position information.

[0008] According to the present disclosure, an encoder capable of suppressing a decrease in detection accuracy can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a diagram showing a motor including the encoder according to the embodiment.

[0010] Figure 2A It shows Figure 1 a rotating plate of the encoder.

[0011] Figure 2B It shows Figure 1 a rotating plate of the encoder.

[0012] Figure 3 It shows Figure 1 a functional block diagram of the encoder.

[0013] Figure 4 It is for explaining Figure 1 an example of a determination method of a determination unit of the encoder.

[0014] Figure 5 It shows Figure 1 an example of the light reception intensity of the light received by the light receiving unit of the encoder.

[0015] Figure 6 It is for explaining Figure 1 an example of a determination method and a correction method of a correction unit of the encoder.

[0016] Figure 7 It shows Figure 1 a calculation circuit for calculating the value of a first pattern on the rotating plate of the encoder.

[0017] Figure 8 is a diagram showing a table of values obtained by the Figure 7 calculation circuit.

[0018] Figure 9 is a diagram showing Figure 1 the data flow during the operation of the correction unit of the

[0019] Figure 10 is a diagram for explaining Figure 1 another example of the correction method of the correction unit of the

[0020] Figure 11 is a diagram for explaining Figure 1 another example of the correction method of the correction unit of the

[0021] Figure 12 is a diagram for explaining Figure 1 yet another example of the correction method of the correction unit of the

[0022] Figure 13 is a diagram showing Figure 1 another example of the light reception intensity of the light received by the light receiving unit of the

[0023] Figure 14 is a diagram showing a calculation circuit that calculates values for a first pattern different from the first pattern of the Figure 1 encoder.

[0024] Figure 15 is a diagram showing a table of values obtained by the Figure 14 calculation circuit. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present disclosure will be described. In addition, all the embodiments described below show a specific example of the present disclosure. Therefore, the numerical values, constituent elements, arrangement positions and connection methods of the constituent elements, and the processes and the order of the processes shown in the following embodiments are examples and are not intended to limit the present disclosure. Therefore, among the constituent elements in the following embodiments, the constituent elements not described in the independent claims representing the uppermost concept of the present disclosure are described as arbitrary constituent elements.

[0026] In addition, each drawing is a schematic diagram and is not necessarily drawn strictly. Further, in each drawing, substantially the same structures are denoted by the same reference numerals, and repeated descriptions are omitted or simplified.

[0027] (Embodiment)

[0028] Figure 1 is a diagram showing the motor 1 including the encoder 10 according to the embodiment.Figure 2A And Figure 2B is a view showing Figure 1 the rotating plate 12 of the encoder 10. Figure 2A is a view of the rotating plate 12 observed axially, Figure 2B is a view showing Figure 2A an enlarged view of the portion surrounded by a dashed line. In addition, in Figure 1 , the housing 6, the first pattern 24, and the second pattern 26 are shown in a sectional view. Additionally, in the following description, the axial direction indicates the direction in which the rotation axis A extends (refer to Figure 1 arrow X), the radial direction indicates the radial direction centered on the rotation axis A (refer to Figure 2A and Figure 2B arrow Y), and the circumferential direction indicates the circumferential direction around the rotation axis A centered on the rotation axis A (refer to Figure 2A and Figure 2B arrow Z). The radial direction is perpendicular to the circumferential direction and the rotation axis. Refer to Figure 1 and Figure 2A and Figure 2B to describe the structure of the encoder 10.

[0029] As Figure 1 shown, the motor 1 includes a main body 2, a stator 3, a rotor 4, a rotating shaft 5, a housing 6, and an encoder 10.

[0030] 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 arranged to be rotatable relative to the stator 3.

[0031] The rotating shaft 5 is rod-shaped such as cylindrical, 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 this power. An encoder 10 is provided at one end in the axial direction of the rotating shaft 5. A load (not shown) etc. that is rotationally driven by the rotation of the rotating shaft 5 is mounted at the other end in the axial direction of the rotating shaft 5. For example, the rotating shaft 5 is formed of a magnetic metal such as iron.

[0032] The housing 6 is mounted on the main body 2 so as to cover one end in the axial direction of the rotating shaft 5 and the encoder 10 etc. For example, the housing 6 is formed of a magnetic metal such as iron.

[0033] The encoder 10 detects the rotation of the detection object. Specifically, the encoder 10 detects the position (rotation position) of the detection object, the rotation direction of the detection object, and the rotational speed of the detection object, etc. In the present embodiment, the detection object is the rotating shaft 5. That is, the encoder 10 detects the position of the rotating shaft 5, the rotation direction of the rotating shaft 5, and the rotational speed of the rotating shaft 5, etc.

[0034] As described above, the encoder 10 is provided at one end in the axial direction of the rotating shaft 5. As Figure 1 and Figure 2A and Figure 2B shown, the encoder 10 includes a rotating plate 12, a first substrate 14, a second substrate 16, an irradiation unit 18, and a light receiving unit 20.

[0035] The rotating plate 12 is a rotating plate that rotates about the rotation axis A. The rotating plate 12 has a main body 22, a first pattern 24, and a second pattern 26.

[0036] The main body 22 is a plate-shaped member that extends in a direction orthogonal to the axial direction and is circular when viewed from the axial direction. The main body 22 is mounted at one end in the axial direction of the rotating shaft 5 and rotates about the rotation axis A together with the rotating shaft 5. The axis of the main body 22 coincides with the rotation axis A. For example, the main body 22 is formed of transparent glass or the like that allows light to pass through.

[0037] 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 a ring shape along the circumferential direction. The first pattern 24 rotates together with the main body 22. In the present embodiment, the first pattern 24 is an absolute pattern. The first pattern 24 has a plurality of first light guiding portions 28 and a plurality of first non-light guiding portions 30.

[0038] The plurality of first light guiding portions 28 are arranged at intervals along the circumferential direction. Each of the plurality of first light guiding portions 28 is formed by arranging first unit regions 32 that guide the light emitted from the irradiation unit 18 to the light receiving unit 20 along the circumferential direction. That is, each of the plurality of first light guiding portions 28 is a region formed by one or more first unit regions 32 and is used to guide the light emitted from the irradiation unit 18 to the light receiving unit 20. The first unit region 32 is a region whose size is predetermined. For example, the first unit region 32 is formed of transparent glass or the like that allows light to pass through.

[0039] The number of first unit regions 32 that constitute each of the plurality of first light guiding portions 28 is different. The size of each of the plurality of first light guiding portions 28 in the circumferential direction is determined according to the number of first unit regions 32 that constitute the first light guiding portion 28, and the sizes of the plurality of first light guiding portions 28 in the circumferential direction are different. In addition, in Figure 2B , in order to avoid complication of the drawings, only a part of the first unit regions 32 are illustrated (refer to the double-dot chain line).

[0040] A plurality of first non-light guiding portions 30 are arranged at intervals in the circumferential direction. Specifically, each of the plurality of first non-light guiding portions 30 is disposed between adjacent first light guiding portions 28 among the plurality of first light guiding portions 28. That is to say, the first pattern 24 has a structure in which the first light guiding portions 28 and the first non-light guiding portions 30 are alternately arranged in the circumferential direction. Each of the plurality of first non-light guiding portions 30 is formed by arranging second unit regions 34 that do not guide the light emitted from the irradiation portion 18 to the light receiving portion 20 in the circumferential direction. That is to say, each of the plurality of first non-light guiding portions 30 is a region composed of one or more second unit regions 34, and is used to prevent the light from passing through and being guided to the light receiving portion 20 when the light is emitted from the irradiation portion 18. The second unit region 34 is a region whose size is predetermined, and does not allow the light to pass through and be guided to the light receiving portion 20 when the light is emitted from the irradiation portion 18. The size of the second unit region 34 is the same as that of the first unit region 32. For example, the second unit region 34 is formed by black chromium plating or the like that does not allow light to pass through.

[0041] The number of second unit regions 34 constituting each of the plurality of first non-light guiding portions 30 is different. The circumferential dimension of each of the plurality of first non-light guiding portions 30 is determined according to the number of second unit regions 34 constituting the first non-light guiding portion 30, and the circumferential dimensions of each of the plurality of first non-light guiding portions 30 are different. In addition, in Figure 2B order to avoid complicating the drawings, only a part of the second unit regions 34 are illustrated (refer to the dashed-dotted line).

[0042] As described above, each of the plurality of first light guiding portions 28 is formed by arranging one or more first unit regions 32 in the circumferential direction, and each of the plurality of first non-light guiding portions 30 is formed by arranging one or more second unit regions 34 in the circumferential direction. That is to say, the first pattern 24 has a structure in which the first unit regions 32 and the second unit regions 34 are arranged in the circumferential direction.

[0043] 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 at a position radially inward of the first pattern 24, and the second pattern 26 is provided in a ring shape in the circumferential direction.

[0044] The second pattern 26 rotates together with the main body 22. In the present embodiment, the second pattern 26 is an absolute pattern.

[0045] The second pattern 26 has a plurality of second light guiding portions 36 and a plurality of second non-light guiding portions 38.

[0046] A plurality of second light guide portions 36 are arranged at intervals in the circumferential direction. Each of the plurality of second light guide portions 36 is formed by arranging first unit regions 40 that guide the light emitted from the irradiation portion 18 to the light receiving portion 20 in the circumferential direction. That is, each of the plurality of second light guide portions 36 is a region composed of one or more first unit regions 40 and is used to guide the light emitted from the irradiation portion 18 to the light receiving portion 20. The first unit region 40 is a region whose size is predetermined and allows the light emitted from the irradiation portion 18 to pass through and be guided to the light receiving portion 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 allows light to pass through.

[0047] The number of first unit regions 40 constituting each of the plurality of second light guide portions 36 is different. The size of each of the plurality of second light guide portions 36 in the circumferential direction is determined according to the number of first unit regions 40 constituting the second light guide portion 36, and the sizes of the plurality of second light guide portions 36 in the circumferential direction are different. In addition, in Figure 2B order to avoid complicating the drawings, only a part of the first unit regions 40 are illustrated (see the dashed-dotted line).

[0048] Each of the plurality of second light guide portions 36 corresponds to each of the plurality of first non-light guide portions 30. In the present embodiment, each of the plurality of second light guide portions 36 is adjacent to the corresponding first non-light guide portion 30 in the radial direction. The number of first unit regions 40 constituting the second light guide portion 36 is the same as the number of second unit regions 34 constituting the first non-light guide portion 30 corresponding to the second light guide portion 36.

[0049] That is, each of the plurality of first unit regions 40 in the second pattern 26 corresponds to each of the plurality of second unit regions 34 in the first pattern 24. In the present embodiment, each of the plurality of first unit regions 40 in the second pattern 26 is adjacent to the corresponding second unit region 34 in the first pattern 24 in the radial direction.

[0050] A plurality of second non-light guiding portions 38 are arranged at intervals in the circumferential direction. Specifically, each of the plurality of second non-light guiding portions 38 is disposed between adjacent second light guiding portions 36 among the plurality of second light guiding portions 36. That is to say, the second pattern 26 has a structure in which the second light guiding portions 36 and the second non-light guiding portions 38 are alternately arranged in the circumferential direction. Each of the plurality of second non-light guiding portions 38 is formed by arranging second unit regions 42 that do not guide the light emitted from the irradiation portion 18 to the light receiving portion 20 in the circumferential direction. That is to say, each of the plurality of second non-light guiding portions 38 is a region composed of one or more second unit regions 42, and is used to prevent the light from passing through and being guided to the light receiving portion 20 when the light is emitted from the irradiation portion 18. The second unit region 42 is a region whose size is predetermined, and does not allow the light to pass through and be guided to the light receiving portion 20 when the light is emitted from the irradiation portion 18. The size of the second unit region 42 is the same as the size of the first unit region 40. In addition, 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 black chromium plating or the like that does not allow light to pass through.

[0051] The number of second unit regions 42 constituting each of the plurality of second non-light guiding portions 38 is different. The circumferential dimension of each of the plurality of second non-light guiding portions 38 is determined according to the number of second unit regions 42 constituting the second non-light guiding portion 38, and the circumferential dimensions of the plurality of second non-light guiding portions 38 are different. In addition, in Figure 2B order to avoid complication of the drawings, only a part of the second unit regions 42 are illustrated (refer to the dashed-dotted line).

[0052] Each of the plurality of second non-light guiding portions 38 corresponds to each of the plurality of first light guiding portions 28. In the present embodiment, each of the plurality of second non-light guiding portions 38 is adjacent to the corresponding first light guiding portion 28 among the plurality of first light guiding portions 28 in the radial direction. The number of second unit regions 42 constituting the second non-light guiding portion 38 is the same as the number of first unit regions 32 constituting the first light guiding portion 28 corresponding to the second non-light guiding portion 38.

[0053] That is to say, each of the plurality of second unit regions 42 in the second pattern 26 corresponds to each of the plurality of first unit regions 32 in the first pattern 24. In the present embodiment, each of the plurality of second unit regions 42 in the second pattern 26 is adjacent to the corresponding first unit region 32 among the plurality of first unit regions 32 in the first pattern 24 in the radial direction.

[0054] As described above, each of the plurality of second light guide portions 36 is formed by arranging one or more first unit regions 40 in the circumferential direction, and each of the plurality of second non-light guide portions 38 is formed by arranging one or more second unit regions 42 in the circumferential direction. That is to say, the second pattern 26 has a structure in which the first unit region 40 and the second unit region 42 are arranged in the circumferential direction.

[0055] In addition, each of the plurality of first unit regions 40 in the second pattern 26 corresponds to each of the plurality of second unit regions 34 in the first pattern 24, and each of the plurality of second unit regions 42 in the second pattern 26 corresponds to each of the plurality of first unit regions 32 in the first pattern 24. The arrangement order of the first unit region 32 and the second unit region 34 in the first pattern 24 is opposite to the arrangement order of the first unit region 40 and the second unit region 42 in the second pattern 26. The first unit region 32 and the second unit region 34 in the first pattern 24 are arranged in a direction (radial direction, arrow Y) perpendicular to the rotation direction (arrow B) of the rotating plate 12, that is, opposite 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 arranged in the radial direction, and the second unit region 34 in the first pattern 24 and the first unit region 40 in the second pattern 26 are arranged in another radial direction.

[0056] The second pattern 26 is provided such that when the first unit region 32 is irradiated with light from the irradiation unit 18, the second unit region 42 corresponding to the first unit region 32 is also irradiated with light from the irradiation unit 18. In addition, the second pattern 26 is provided such that when the second unit region 34 is irradiated with light from the irradiation unit 18, the first unit region 40 corresponding to the second unit region 34 is also irradiated with light from the irradiation unit 18. By providing the second pattern 26 in this way, the output value of the first light receiving member 48 can be made opposite to the output value of the second light receiving member 50. That is to say, the second pattern 26 is provided such that the output value of the second light receiving member 50 is a value opposite to the output value of the first light receiving member 48.

[0057] As Figure 1 shown, the first substrate 14 extends in a direction orthogonal to the axial direction. The first substrate 14 is provided at an interval 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 housing 6 and does not rotate with the rotating shaft 5.

[0058] The second substrate 16 extends in a direction orthogonal to the axial direction. The second substrate 16 is disposed at an axial interval from the rotating plate 12 and faces the rotating plate 12. The second substrate 16 is disposed on the side opposite to the first substrate 14 with respect to the rotating plate 12. The second substrate 16 is fixed to the inner surface of the housing 6 and does not rotate together with the rotating shaft 5.

[0059] The irradiation unit 18 includes a first light emitting unit 44 and a second light emitting unit 46 for irradiating light to the first pattern 24 and the second pattern 26.

[0060] 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 irradiates light to the first pattern 24. For example, the first light emitting unit 44 is implemented by a light emitting module or the like.

[0061] 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 light to the second pattern 26. For example, the second light emitting unit 46 is implemented by a light emitting module or the like.

[0062] The light receiving unit 20 receives the light irradiated from the irradiation unit 18 to the first pattern 24 and passing through the first pattern 24, and the light irradiated from the irradiation unit 18 to the second pattern 26 and passing through the second pattern 26. The light receiving unit 20 includes a first light receiving member 48 and a second light receiving member 50.

[0063] 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 the light that has passed through the first pattern 24. In addition, the first light receiving member 48 binarizes the intensity of the received light and then outputs it. For example, the first light receiving member 48 is implemented by a light receiving element or the like.

[0064] 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 the light that has passed through the second pattern 26. In addition, the second light receiving member 50 binarizes the intensity of the received light and then outputs it. For example, the second light receiving member 50 is implemented by a light receiving element or the like.

[0065] Figure 3 is a block diagram showing Figure 1 the functional structure of the encoder 10. Refer to Figure 3 to describe the functional structure of the encoder 10.

[0066] As Figure 3 shown, the encoder 10 further includes a determination unit 52 and a correction unit 54.

[0067] The first light receiving member 48 binarizes the intensity of the received light and outputs and 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 set in advance, and outputs one of two values according to the comparison result. In the present embodiment, the first light receiving member 48 outputs "1" when the intensity of the received light is equal to or greater than the predetermined threshold value, and outputs "0" when the intensity of the received light is less than the predetermined threshold value.

[0068] The second light receiving member 50 binarizes the intensity of the received light and outputs and transmits it to the determination unit 52. Specifically, the second light receiving member 50 compares the intensity of the received light with a predetermined threshold value set in advance, and outputs one of two values according to the comparison result. In the present embodiment, the second light receiving member 50 outputs "1" when the intensity of the received light is equal to or greater than the predetermined threshold value, and outputs "0" when the intensity of the received light is less than the predetermined threshold value.

[0069] 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 in error. Specifically, when the output value of the second light receiving member 50 is the opposite value of the output value of the first light receiving member 48, the determination unit 52 determines that the output values of the first light receiving member 48 and the second light receiving member 50 are not in error, and outputs the determination result. When the output value of the second light receiving member 50 is not the opposite value of the output value of the first light receiving member 48, the determination unit 52 determines that one of the output values of the first light receiving member 48 and the second light receiving member 50 is in error, and outputs the determination result. For example, the determination unit 52 is implemented by a processor or the like.

[0070] For example, when 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", the determination unit 52 determines that these output values are not in error. When 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", the determination unit 52 determines that one of these output values is in error.

[0071] When it is determined by the determination unit 52 that one of the output values of the first light receiving member 48 and the second light receiving member 50 is in error, the correction unit 54 determines whether the output value of the first light receiving member 48 is in error. When the output value of the first light receiving member 48 is in error, the correction unit 54 corrects the output value of the first light receiving member 48 to the correct value and outputs it. The determination method and correction method of the correction unit 54 will be described later. For example, the correction unit 54 is implemented by a processor or the like.

[0072] Figure 4 This is a diagram showing an example of the determination method of the determination unit 52 of the encoder 10 for explanation. Figure 1 This is a diagram showing an example of the determination method of the determination unit 52 of the encoder 10 for explanation. Figure 4 Part (a) of this is a diagram schematically showing the first pattern 24 and the output values of the first light-receiving member 48. Figure 4 Part (b) of this is a diagram schematically showing the second pattern 26 and the output values of the second light-receiving member 50. Figure 4 Part (c) of this is a diagram showing the total value of the output values of the first light-receiving member 48 and the second light-receiving member 50. Figure 5 This is a diagram showing Figure 1 an example of the light-receiving intensity of the light received by the light-receiving unit 20 of the encoder 10 for explanation. Figure 5 Part (a) of this shows an example of the light-receiving intensity of the light received by the first light-receiving member 48. Figure 5 Part (b) of this shows an example of the light-receiving intensity of the light received by the second light-receiving member 50. Refer to Figure 4 and Figure 5 to explain an example of the determination method of the determination unit 52.

[0073] As Figure 4 shown in part (a) of this, in the first pattern 24, the first unit region 32 and the second unit region 34 are arranged along the rotation direction of the rotating plate 12 (refer to Figure 4 arrow B in this). Hereinafter, the rotation direction of the rotating plate 12 will be simply referred to as the rotation direction. The rotation direction coincides with the circumferential direction and is along the circumferential direction. In addition, the first unit region 32 and the second unit region 34 will 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 that is an arrangement of M unit regions and is used to output position information indicating the position of the rotation shaft 5 to be detected; and a second arrangement that is an arrangement of N unit regions adjacent to the first arrangement and is used to output correction information for correcting the position information. In the present embodiment, M = 9 and N = 2.

[0074] The first light-receiving member 48 receives the LED light irradiated from the irradiation unit 18 and transmitted through the first pattern 24, and outputs the intensity of the received light after binarization. For example, when the first light-receiving member 48 faces the first unit region 32 and sufficiently receives the light transmitted through the first unit region 32, the intensity of the received light is above a specified threshold value, and the first light-receiving member 48 outputs "1". On the other hand, when the first light-receiving member 48 faces the second unit region 34 and cannot sufficiently receive the light through the second unit region 34, the intensity of the received light is less than the specified threshold value, and the first light-receiving member 48 outputs "0".

[0075] By rotating the rotary plate 12, the first light-receiving member 48 faces either the first unit region 32 or the second unit region 34 arranged in the circumferential direction in sequence. Each time the first light-receiving member 48 faces either the first unit region 32 or the second unit region 34, it binarizes the received light intensity and outputs it.

[0076] For example, the first light-receiving member 48 outputs 9 values by facing each unit region in the first arrangement. The leading unit region in the rotation direction of the first arrangement is the first unit region 32. The first light-receiving member 48 receives the light irradiated from the irradiation unit 18 and transmitted through the first unit region 32 by facing the first unit region 32. In the following description, the leading unit region in the rotation direction is simply referred to as the leading unit region. As Figure 5 shown in (a) of

[0077] the intensity of the light received by the first light-receiving member 48 by facing the first unit region 32 is above a specified threshold value, and the first light-receiving member 48 outputs "1".

[0078] On the other hand, the second unit region starting from the leading unit region in the first arrangement is the second unit region 34. When the first light-receiving member 48 faces the second unit region 34, it cannot receive the light irradiated from the irradiation unit 18 sufficiently. Therefore, the intensity of the light received by the first light-receiving member 48 by facing the second unit region 34 is less than the specified threshold value, and thus the first light-receiving member 48 outputs "0".

[0079] In this way, the 9 output values output based on the first arrangement are position information indicating the position of the rotation axis 5, and the position of the rotation axis 5 etc. can be determined according to the combination of the 9 output values.

[0080] The output values output based on the second arrangement will be described later.

[0081] As Figure 4As shown in (b) thereof, in the second pattern 26, the first unit region 40 and the second unit region 42 are arranged in the rotational direction. Hereinafter, the first unit region 40 and the second unit region 42 will be simply referred to as unit regions. Here, 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 and is used for outputting position information indicating the position of the rotation axis 5 to be detected; and a second arrangement which is an arrangement of N unit regions adjacent to the first arrangement and is used for outputting correction information for correcting the position information. In the present embodiment, M = 9 and N = 2.

[0082] The second light receiving member 50 receives the LED light irradiated from the irradiation unit 18 and transmitted through the second pattern 26, and outputs the intensity of the received light after binarization. For example, when the second light receiving member 50 faces the first unit region 40 and receives the light transmitted through the first unit region 40, the intensity of the received light is equal to or higher than a prescribed threshold value, and the second light receiving member 50 outputs "1". On the other hand, when the second light receiving member 50 faces the second unit region 42 and cannot sufficiently receive the light through the second unit region 42, the intensity of the received light is less than the prescribed threshold value, and the second light receiving member 50 outputs "0".

[0083] By rotating the rotating plate 12, the second light receiving member 50 sequentially faces either the first unit region 40 or the second unit region 42 arranged in the circumferential direction, and the second light receiving member 50 outputs the received light intensity after binarization each time it faces either the first unit region 40 or the second unit region 42.

[0084] For example, the second light receiving member 50 outputs 9 values by facing each unit region of the first arrangement. The head of the first arrangement is the second unit region 42, and the second light receiving member 50 cannot sufficiently receive the light irradiated from the irradiation unit 18 when facing the second unit region 42. As Figure 5 shown in (b) thereof, the intensity of the light received by the second light receiving member 50 when facing the second unit region 42 is less than the prescribed threshold value, so the second light receiving member 50 outputs "0".

[0085] On the other hand, the second unit region from the head of the first arrangement is the first unit region 40. When the second light receiving member 50 faces the first unit region 40, it receives the light irradiated from the irradiation unit 18 and transmitted through the first unit region 40. The intensity of the light received by the second light receiving member 50 when facing the first unit region 40 is equal to or higher than the prescribed threshold value, so the second light receiving member 50 outputs "1".

[0086] The order of the first arrangement in the second pattern 26 is opposite to the order of the first arrangement in the first pattern 24. Therefore, by reversing the output value of the second light-receiving member 50 output based on the first arrangement in the second pattern 26 to be the same as the output value of the first light-receiving member 48 output based on the first arrangement in the first pattern 24, position information indicating the position of the rotation shaft 5 is obtained.

[0087] In addition, the order of the second arrangement in the second pattern 26 is opposite to the order of the second arrangement in the first pattern 24. Therefore, by reversing the output value of the second light-receiving member 50 output based on the second arrangement in the second pattern 26 to be the same as the output value of the first light-receiving member 48 output based on the second arrangement in the first pattern 24, correction information for correcting the position information is obtained.

[0088] Furthermore, in the present embodiment, reversing the output value means changing "1" to "0" and "0" to "1".

[0089] As Figure 4 shown in (c) of [], the determination unit 52 determines whether the output value of the second light-receiving member 50 is a value opposite to the output value of the first light-receiving member 48 by adding up the output value of the first light-receiving member 48 and the output value of the second light-receiving member 50 corresponding to this output value. Specifically, the determination unit 52 adds up the output value of the first light-receiving member 48 and the output value of the second light-receiving member 50 corresponding to this output value. If the sum value is "1", these output values are opposite to each other, and it is determined that these output values have not erred. The determination unit 52 adds up the output value of the first light-receiving member 48 and the output value of the second light-receiving member 50 corresponding to this output value. If the sum value is "0", these output values are not opposite to each other, and it is determined that an error has occurred in one of these output values.

[0090] For example, the output value "1" obtained based on the leading unit area in the first arrangement of the first pattern 24 corresponds to the output value "0" obtained based on the leading unit area in the first arrangement of the second pattern 26. When these corresponding output values are added up, it is "1" + "0" = "1", and the sum value is "1". Therefore, the determination unit 52 determines that these output values have not erred.

[0091] On the other hand, for example, the output value "0" obtained based on the fifth unit area from the leading position in the first arrangement of the first pattern 24 corresponds to the output value "0" obtained based on the fifth unit area from the leading position in the first arrangement of the second pattern 26. When these corresponding output values are added up, it is "0" + "0" = "0", and the sum value is "0". Therefore, the determination unit 52 determines that an error has occurred in one of these output values.

[0092] For example, in the case where two patterns are provided with the same arrangement order of the first unit region and the second unit region, the output values output based on the second unit region of one pattern and the output values output based on the second unit region of the other pattern corresponding to the second unit region are both "0". In addition, there is the following situation: when foreign matter 7 adheres to both the first unit region of one pattern and the first unit region of the other pattern corresponding to the first unit region, the output values output based on these two first unit regions are also both "0". In the case where two patterns are provided with the same arrangement order of the first unit region and the second unit region like this, it is impossible to determine whether the value is output based on the second unit region or the first unit region to which foreign matter adheres. Therefore, there are cases where the error in the output value is not detected and the position of the rotation shaft 5 is erroneously detected, etc., resulting in a decrease in detection accuracy.

[0093] In the present embodiment, the output value of the first light receiving member 48 is opposite to the output value of the second light receiving member 50 corresponding to the output value. That is, (the output value of the first light receiving member 48, the output value of the second light receiving member 50 corresponding to the output value) = (1, 0) or (0, 1). Therefore, the sum value of these output values is "1" in principle. From this, it can be known that when the sum value 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 the output value are not in error, and when the sum value is not "1", one of these output values is in error. In this way, it is possible to detect that an error has occurred in the output value, so it is possible to suppress a decrease in detection accuracy.

[0094] In the encoder of Patent Document 1, when dust or the like adheres to the pattern, the light from the light source is difficult to transmit or reflect due to the dust or the like, and there is a case of erroneous detection. And there is a case where the erroneous detection is not detected and the detection accuracy is reduced. In addition, even if the occurrence of the erroneous detection is detected, it is difficult to correct the error, and the detection accuracy is reduced.

[0095] In contrast, the encoder 10 in the embodiment can suppress a decrease in detection accuracy as described above.

[0096] Figure 6 It is for explaining Figure 1 An example of the determination method and correction method of the correction unit 54 of the encoder 10. Figure 6 (a) of is a diagram for explaining the case of using the output value output based on the unit region at the head of the second arrangement, Figure 6 and (b) of is a diagram for explaining the case of using the output value output based on the second unit region from the head of the second arrangement.

[0097] In Figure 6In (a) of , the following method is described: When the determination unit 52 determines that an error has occurred in either the output value output from the third unit region from the head of the first arrangement based on the first pattern 24 or the output value output from the third unit region from the head of the first arrangement based on the second pattern 26, it is determined whether the output value output from this unit region based on the first pattern 24 is correct, and if an error has occurred, the output value is corrected.

[0098] As Figure 6 As shown in (a) of , in addition to obtaining the 9 output values output based on the first arrangement, the correction unit 54 also obtains 2 output values output based on the second arrangement. The 2 output values output based on the second arrangement are the output values output from the first light-receiving member 48 in the same manner as the 9 output values output based on the first arrangement. The 2 output values output based on the second arrangement are correction information for correcting at least one of the 9 output values that is position information indicating the position of the rotation axis 5.

[0099] In the present embodiment, the output value output from the unit region at the head of the second arrangement is information for determining whether an error has occurred in the output value output from each of the unit regions at the head of the first arrangement, the third unit region from the head, the fifth unit region from the head, the sixth unit region from the head, the seventh unit region from the head, and the eighth unit region from the head, which is determined by the determination unit 52 as possibly having an error, and is information for correcting the one output value if an error has occurred in the one output value.

[0100] When the value obtained by taking the exclusive OR of the output value output from the unit region at the head of the first arrangement and the output value output from the third unit region from the head is set as the first value, the value obtained by taking the exclusive OR of the first value and the output value output from the fifth unit region from the head is set as the second value, the value obtained by taking the exclusive OR of the second value and the output value output from the sixth unit region from the head is set as the third value, the value obtained by taking the exclusive OR of the third value and the output value output from the seventh unit region from the head is set as the fourth value, and the value obtained by taking the exclusive OR of the fourth value and the output value output from the eighth unit region from the head is set as the fifth value, the output value obtained from the unit region at the head of the second arrangement is equal to the fifth value.

[0101] For example, when the output value output from the unit area at the head of the second arrangement is "0", the sum of the output values output from each of the unit areas of the unit area at the head of the first arrangement, the third unit area from the head, the fifth unit area from the head, the sixth unit area from the head, the seventh unit area from the head, and the eighth unit area from the head is an even number.

[0102] On the other hand, when the output value output from the unit area at the head of the second arrangement is "1", the sum of the output values output from each of the unit areas of the unit area at the head of the first arrangement, the third unit area from the head, the fifth unit area from the head, the sixth unit area from the head, the seventh unit area from the head, and the eighth unit area from the head is an odd number.

[0103] In Figure 6 in (a), the output value obtained from the unit area at the head of the second arrangement is "0". In addition, the sum of the output values output from each of the unit areas of the unit area at the head of the first arrangement, the third unit area from the head, the fifth unit area from the head, the sixth unit area from the head, the seventh unit area from the head, and the eighth unit area from the head is "0" + "0" + "1" + "1" + "0" + "1" = "3", which is an odd number. Therefore, it can be known that an error has occurred in one of the output values output from each of the unit areas of the unit area at the head of the first arrangement, the third unit area from the head, the fifth unit area from the head, the sixth unit area from the head, the seventh unit area from the head, and the eighth unit area from the head.

[0104] As described above, here, it is determined that an error has occurred in one of the output values output from the third unit area from the head of the first arrangement of the first pattern 24 and the output value output from the third unit area from the head of the first arrangement of the second pattern 26. Therefore, the correction unit 54 determines that an error has occurred in the output value obtained from the third unit area from the head among the output values output from each of the unit areas of the unit area at the head of the first arrangement, the third unit area from the head, the fifth unit area from the head, the sixth unit area from the head, the seventh unit area from the head, and the eighth unit area from the head of the first pattern 24, corrects the output value from "0" to "1", and outputs it.

[0105] In Figure 6In (b) of , the following method is described: When the determination unit 52 determines that an error has occurred in either the output value output from the fourth unit region from the head of the first arrangement based on the first pattern 24 or the output value output from the fourth unit region from the head of the first arrangement based on the second pattern 26, it is determined whether the output value output from this unit region based on the first pattern 24 is correct, and if an error has occurred, the output value is corrected.

[0106] As Figure 6 shown in (b) of , similar to Figure 6 the case shown in (a) of , the correction unit 54 obtains, in addition to the 9 output values obtained based on the first arrangement, 2 output values obtained based on the second arrangement.

[0107] In the present embodiment, the output value output from the second unit region from the head based on the second arrangement is information for determining whether an error has occurred in one of the output values output from the second, fourth, sixth, seventh, eighth, and ninth unit regions from the head based on the first arrangement, which is determined by the determination unit 52 as possibly having an error, and is information for correcting this one value when an error has occurred in this one value.

[0108] When the value obtained by taking the exclusive OR of the output value output from the second unit region from the head based on the first arrangement and the output value output from the fourth unit region from the head is set as the sixth value, the value obtained by taking the exclusive OR of the sixth value and the output value output from the sixth unit region from the head is set as the seventh value, the value obtained by taking the exclusive OR of the seventh value and the output value output from the seventh unit region from the head is set as the eighth value, the value obtained by taking the exclusive OR of the eighth value and the output value output from the eighth unit region from the head is set as the ninth value, and the value obtained by taking the exclusive OR of the ninth value and the output value output from the ninth unit region from the head is set as the tenth value, the output value output from the second unit region from the head based on the second arrangement is equal to the tenth value.

[0109] For example, when the output value obtained from the second unit region from the head based on the second arrangement is "0", the sum of the output values output from each of the second, fourth, sixth, seventh, eighth, and ninth unit regions from the head based on the first arrangement is an even number.

[0110] On the other hand, when the output value obtained from the second unit region from the head based on the second arrangement is "1", the sum of the output values output from each of the second unit region from the head, the fourth unit region from the head, the sixth unit region from the head, the seventh unit region from the head, the eighth unit region from the head, and the ninth unit region from the head based on the first arrangement is an odd number.

[0111] In Figure 6 (b) of, the output value output from the second unit region from the head based on the second arrangement is "0". In addition, the sum of the output values output from each of the second unit region from the head, the fourth unit region from the head, the sixth unit region from the head, the seventh unit region from the head, the eighth unit region from the head, and the ninth unit region from the head based on the first arrangement is "1" + "0" + "0" + "0" + "0" + "1" = "2", which is an even number. Therefore, the correction unit 54 determines that the output value output from the fourth unit region from the head based on the first arrangement of the first pattern 24 is not in error, and outputs "0" without correcting the output value.

[0112] In addition, by making the output values output from the first arrangement and the second arrangement of the second pattern 26 opposite to each other, the same processing as the above-described processing can be performed.

[0113] Figure 7 is a diagram showing a calculation circuit 56 that calculates the values of the first pattern 24 on the rotary plate 12 of the encoder 10 used for forming Figure 1 . Figure 8 is a table showing the values obtained by the Figure 7 calculation circuit 56.

[0114] Figure 7 The calculation circuit 56 shown is a circuit for calculating the value based on the M code (irreducible polynomial): X 9 + X 8 + X 7 + X 6 + X 5 + X 3 + 1. By forming the first pattern 24 based on the value obtained by the calculation circuit 56, the first pattern 24 having the first arrangement and the second arrangement can be formed.

[0115] As Figure 7 shown, the calculation circuit 56 includes a plurality of registers 58 to 74 and a plurality of XOR circuits 76 to 86.

[0116] Values for operations of the calculation circuit 56 are stored in respective ones of a plurality of registers 58 to 74, and each of the plurality of registers 58 to 74 outputs the stored value.

[0117] 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.

[0118] Each of a plurality of XOR circuits 76 to 86 calculates the exclusive OR of two input values and outputs the calculated value. The value output from register 58 and the value output from register 62 are input to XOR circuit 76, and XOR circuit 76 calculates the exclusive OR of these two values and outputs the calculated value. The value output from register 66 and the value output from XOR circuit 76 are input to XOR circuit 78, and XOR circuit 78 calculates the exclusive OR of these two values and outputs the calculated value. The value output from register 68 and the value output from XOR circuit 78 are input to XOR circuit 80, and XOR circuit 80 calculates the exclusive OR of these two values and outputs the calculated value. The value output from register 70 and the value output from XOR circuit 80 are input to XOR circuit 82, and XOR circuit 82 calculates the exclusive OR of these two values and outputs the calculated value. The value output from register 72 and the value output from XOR circuit 82 are input to XOR circuit 84, and XOR circuit 84 calculates the exclusive OR of these two values and outputs the calculated value. A predetermined value input from the outside and the value output from XOR circuit 84 are input to XOR circuit 86, and XOR circuit 86 calculates the exclusive OR of these two values and outputs the calculated value. For example, the predetermined value is one value determined in advance. The value output from XOR circuit 86 is input to register 74.

[0119] Each of the plurality of registers 58 to 74 outputs the input value whenever a new value is input. Each of the plurality of XOR circuits 76 to 86 calculates the exclusive OR of two input values and outputs the result whenever two new values are input.

[0120] Here, a case is described where "0" is pre-stored in registers 58, 60, 64, 70, and 74, and "1" is pre-stored in registers 62, 66, 68, and 72.

[0121] In this case, first, registers 58, 60, 64, 70, and 74 output "0", and registers 62, 66, 68, and 72 output "1".

[0122] XOR circuit 76 outputs the exclusive OR of "0" and "1", that is, "1". XOR circuit 78 outputs the exclusive OR of "1" and "1", that is, "0", XOR circuit 80 outputs the exclusive OR of "1" and "0", that is, "1", XOR circuit 82 outputs the exclusive OR of "0" and "1", that is, "1", XOR circuit 84 outputs the exclusive OR of "1" and "1", that is, "0". "0" is input to XOR circuit 86 from the outside, and XOR circuit 86 outputs the exclusive OR of "0" and "0", that is, "0".

[0123] As described above, each of the multiple registers 58 to 74 outputs the input value whenever a new value is input. Each of the multiple XOR circuits 76 to 86 calculates and outputs the exclusive OR of the two input values whenever two new values are input. By repeating the calculation and output of the exclusive OR in this way, Figure 8 the values shown are obtained.

[0124] As Figure 8 shown, the nine output values output from the multiple registers 58 to 74 are values for forming the first permutation. For example, when observing Figure 8 the first row of the output values in the shown table, the nine output values output from the multiple registers 58 to 74 are "001011010". In this case, by arranging the second unit regions 34, the second unit regions 34, the first unit region 32, the second unit regions 34, the first unit region 32, the first unit regions 32, the second unit regions 34, the first unit region 32, and the second unit regions 34 in this order along the circumferential direction, the first permutation can be formed.

[0125] The value output from register 60 is then output by register 58, the value output from register 62 is then output by register 60, the value output from register 64 is then output by register 62, the value output from register 66 is then output by register 64, the value output from register 68 is then output by register 66. In addition, the value output from register 70 is then output by register 68, the value output from register 72 is then output by register 70, the value output from register 74 is then output by register 72, the value output from XOR circuit 86 is then output by register 74, and XOR circuit 86 calculates and outputs a new value based on these values. The above process is repeated.

[0126] As described above, the nine output values output from the plurality of registers 58 to 74 are values for forming a first permutation. The value output from the XOR circuit 86 together with the nine output values and the value output from the XOR circuit 86 after that value are values for forming a second permutation corresponding to the first permutation formed based on the nine output values.

[0127] By repeatedly outputting values by the plurality of registers 58 to 74 and the XOR circuit 86, a plurality of values for forming a first permutation can be obtained, and a plurality of first permutations can be formed. That is, using Figure 8 The first pattern 24 formed by the values shown has a plurality of first permutations. The plurality of first permutations in the first pattern 24 are continuously formed in such a manner that the unit regions are shifted one by one. That is, the arrangement of the nine unit regions in the first pattern 24 is a first permutation, and the arrangement of the nine unit regions obtained by shifting the unit regions one by one in the circumferential direction with respect to the arrangement of the nine unit regions is also a first permutation. In the plurality of first permutations, the order in which the first unit region 32 and the second unit region 34 are arranged is different from each other. That is, the plurality of first permutations are formed in such a manner that the arrangements of the nine output values obtained based on each of the first permutations in the plurality of first permutations are different.

[0128] In addition, by repeatedly outputting values by the plurality of registers 58 to 74 and the XOR circuit 86, a plurality of values for forming a second permutation can be obtained, and a plurality of second permutations can be formed. That is, using Figure 8 The first pattern 24 formed by the values shown has a plurality of second permutations. The plurality of second permutations in the first pattern 24 correspond to the plurality of first permutations described above, and each of the plurality of second permutations is an arrangement of two unit regions adjacent to the corresponding first permutation. Each of the plurality of second permutations in the first pattern 24 is an arrangement for outputting correction information for correcting the output value output based on the corresponding first permutation. The plurality of second permutations in the first pattern 24 are continuously formed in such a manner that the unit regions are shifted one by one. That is, the arrangement of the two unit regions in the first pattern 24 is a second permutation, and the arrangement of the two unit regions obtained by shifting the unit regions one by one in the circumferential direction with respect to the arrangement of the two unit regions is also a second permutation.

[0129] Figure 9 is a diagram showing Figure 1 the flow of data during the operation of the correction unit 54 of the encoder 10. In addition, in Figure 9 , "1" in the first permutation and the second permutation represents the first unit region 32, and "0" represents the second unit region 34. In Figure 9 , a case where a foreign object 7 is attached to the third unit region from the head in the first permutation of the first pattern 24 is described.

[0130] AsFigure 9 As shown, 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 these output values are error-free. Regarding the determination method of the determination unit 52, refer to the above description, and thus it is omitted here. The determination unit 52 sends the error location information indicating the output values where an error may have occurred to the correction unit 54.

[0131] The correction unit 54 identifies, based on the error location information, the output values in the output values of the first light receiving member 48 output based on the first arrangement that may have an error. Here, the error location information indicates that the output value output based on the third unit region from the head may have an error.

[0132] The correction unit 54 performs an error determination on whether an error has occurred for the output values that may have an error. Specifically, the correction unit 54 uses the output values other than the output value in question to determine whether an error has occurred for the output values in the output values of the first light receiving member 48 that may have an error. Regarding the determination method of the correction unit 54, refer to the above description, and thus it is omitted here.

[0133] When an error occurs in the output values of the first light receiving member 48, the correction unit 54 performs a correction operation on the data before correction to calculate the corrected data. The corrected data is the value obtained by correcting the output values of the first light receiving member 48. Regarding the correction method of the correction unit 54, refer to the above description, and thus it is omitted here.

[0134] After calculating the corrected data, the correction unit 54 loops to determine whether there are any other output values in the output values of the first light receiving member 48 that have an error.

[0135] After correcting all the output values that can be corrected, the correction unit 54 selects the original data or the corrected data and outputs it to the outside. The original data refers to the same value as the output values of the first light receiving member 48. The correction unit 54 outputs the corrected data for the output values that have an error.

[0136] Figure 10 is for explaining Figure 1 Another example of the correction method of the correction unit 54 of the encoder 10 shown. Figure 10 In (a) of, it is a diagram for explaining the correction of one output value in the output values of the first light receiving member 48, Figure 10 In (b) of, it is a diagram for explaining the correction of another output value in the output values of the first light receiving member 48. Refer to Figure 10 to explain the case of correcting two output values in the output values of the first light receiving member 48.

[0137] As Figure 10As shown in (a) of, the correction unit 54 obtains, in addition to the nine output values (position information) output based on the first permutation, two output values (correction information) output based on the second permutation.

[0138] The output value obtained from the unit region at the head of the second permutation is "0". In addition, the sum of the output values output from each of the unit regions of the unit region at the head of the first permutation, the fifth unit region from the head, the sixth unit region from the head, the seventh unit region from the head, and the eighth unit region from the head is "0" + "1" + "1" + "0" + "1" = "3", which is an odd number. Therefore, in order to make this sum an even number, the correction unit 54 makes the output value output from the third unit region from the head of the first permutation be "1" and outputs "1".

[0139] Next, as Figure 10 shown in (b) of, the correction unit 54 corrects the output value output from the second unit region from the head of the first permutation.

[0140] The output value output from the second unit region from the head of the second permutation is "0". In addition, the sum of the output values output from each of the unit regions of the fourth unit region from the head, the sixth unit region from the head, the seventh unit region from the head, the eighth unit region from the head, and the ninth unit region from the head of the first permutation is "0" + "1" + "0" + "1" + "0" = "2", which is an even number. Therefore, in order to keep this sum in an even state, the correction unit 54 makes the output value output from the second unit region from the head of the first permutation be "0" and outputs "0".

[0141] Figure 11 is a diagram for explaining Figure 1 another example of the correction method of the correction unit 54 of the encoder 10 of. Figure 11 (a) of is a diagram for explaining the correction of one of the output values of the first light-receiving member 48, Figure 11 (b) of is a diagram for explaining the correction of another one of the output values of the first light-receiving member 48. Refer to Figure 11 to explain the case of correcting two output values of the first light-receiving member 48.

[0142] As Figure 11As shown in (a), the output value obtained from the second unit region from the head based on the second arrangement is "0". Additionally, the sum of the output values of each of the unit regions among the second unit region from the head, the fourth unit region from the head, the seventh unit region from the head, the eighth unit region from the head, and the ninth unit region from the head based on the first arrangement is "0" + "0" + "0" + "1" + "0" = "1", which is an odd number. Therefore, in order to make this sum an even number, the correction unit 54 makes the output value of the sixth unit region from the head based on the first arrangement be "1" and outputs "1".

[0143] Next, as Figure 11 shown in (b), the correction unit 54 corrects the output value of the fifth unit region from the head based on the first arrangement using the corrected value.

[0144] The output value of the unit region at the head based on the second arrangement is "0". Additionally, the sum of the output values of each of the unit regions among the unit region at the head, the third unit region from the head, the sixth unit region from the head, the seventh unit region from the head, and the eighth unit region from the head based on the first arrangement is "0" + "1" + "1" + "0" + "1" = "3", which is an odd number. Therefore, in order to make this sum an even number, the correction unit 54 makes the output value of the fifth unit region from the head based on the first arrangement be "1" and outputs "1".

[0145] Figure 12 is a diagram for explaining Figure 1 yet another example of the correction method of the correction unit 54 of the encoder 10. Figure 12 (a) is a diagram for explaining the correction of one of the output values of the first light-receiving member 48, Figure 12 (b) is a diagram for explaining the correction of another output value of the first light-receiving member 48. Refer to Figure 12 to explain the case of correcting two output values of the first light-receiving member 48.

[0146] As Figure 12As shown in (a), the output value obtained based on the unit area at the head of the second arrangement is "0". In addition, the sum of the output values of each unit area among the unit area at the head of the first arrangement, the third unit area from the head, the fifth unit area from the head, the sixth unit area from the head, and the seventh unit area from the head is "0" + "1" + "1" + "1" + "0" = "3", which is an odd number. Therefore, in order to make this sum an even number, the correction unit 54 makes the output value output from the eighth unit area from the head of the first arrangement be "1", and outputs "1".

[0147] Next, as Figure 12 shown in (b), the correction unit 54 uses the corrected value to correct the output value output from the fourth unit area from the head of the first arrangement.

[0148] The output value output from the second unit area from the head of the second arrangement is "0". In addition, the sum of the output values of each unit area among the second unit area from the head, the sixth unit area from the head, the seventh unit area from the head, the eighth unit area from the head, and the ninth unit area from the head of the first arrangement is "0" + "1" + "0" + "1" + "0" = "2", which is an even number. Therefore, in order to keep this sum in an even state, the correction unit 54 makes the output value output from the fourth unit area from the head of the first arrangement be "0", and outputs "0".

[0149] In this way, the correction unit 54 can use the corrected output value to further correct other output values.

[0150] The encoder 10 according to the embodiment has been described above.

[0151] The encoder 10 according to the embodiment includes: a rotating plate 12 having a first pattern 24 and a second pattern 26; an irradiation unit 18 that irradiates light onto the first pattern 24 and the second pattern 26; and a light receiving unit 20 that receives the light irradiated from the irradiation unit 18 and passing through the first pattern 24 and the light irradiated from the irradiation unit 18 and passing through the second pattern 26. The first pattern 24 has a structure in which a first unit region 32 and a second unit region 34 are arranged along the circumferential direction centered on the rotation axis A of the rotating plate 12. The first unit region 32 guides the light irradiated from the irradiation unit 18 to the light receiving unit 20, and the second unit region 34 does not guide the light irradiated from the irradiation unit 18 to the light receiving unit 20. The second pattern 26 has a structure in which a first unit region 40 and a second unit region 42 are arranged along the circumferential direction centered on the rotation axis A of the rotating plate 12. The first unit region 40 guides the light irradiated from the irradiation unit 18 to the light receiving unit 20, and the second unit region 42 does not guide the light irradiated from the irradiation unit 18 to the light receiving unit 20. The arrangement order of the first unit region 32 and the second unit region 34 in the first pattern 24 is opposite to the arrangement order of the first unit region 40 and the second unit region 42 in the second pattern 26.

[0152] Accordingly, it is possible to make the light guided from the first pattern 24 opposite to the light guided from the second pattern 26. 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, when no light is guided from both the first pattern 24 and the second pattern 26 to the light receiving unit 20, it is possible to detect that some abnormality has occurred. For example, even when foreign matter 7 adheres to both the first pattern 24 and the second pattern 26 and no light is guided from both the first pattern 24 and the second pattern 26 to the light receiving unit 20, it is possible to detect that some abnormality has occurred. By detecting the occurrence of such an abnormality in this way, it is possible to suppress the occurrence of false detection and suppress the reduction of detection accuracy.

[0153] In addition, the encoder 10 according to the embodiment further includes a determination unit 52. The light receiving unit 20 includes: a first light receiving member 48 that receives the light irradiated from the irradiation unit 18 and passing through the first pattern 24, binarizes the intensity of the received light, and outputs the result; and a second light receiving member 50 that receives the light irradiated from the irradiation unit 18 and passing through the second pattern 26, binarizes the intensity of the received light, and outputs the result. The second pattern 26 is set such that the output value of the second light receiving member 50 is opposite to the output value of the first light receiving member 48. When the output value of the second light receiving member 50 is not opposite to the output value of the first light receiving member 48, the determination unit 52 determines that an error has occurred in either the output value of the first light receiving member 48 or the output value of the second light receiving member 50, and outputs a determination result.

[0154] Accordingly, it is possible to make the output value of the first light receiving member 48 based on the light passing through the first pattern 24 opposite to the output value of the second light receiving member 50 based on the light passing through the second pattern 26. When these output values are not opposite, the determination unit 52 determines that an error has occurred in either of these output values. Therefore, it is possible to easily detect that an error has occurred in the output value, further suppress the occurrence of false detection, and thus further suppress the reduction in detection accuracy.

[0155] In addition, when the first unit region 32 and the second unit region 34 are referred to as unit regions, the first pattern 24 includes: a first arrangement that is an arrangement of nine unit regions and is used to output position information indicating the position of the rotation axis 5; and a second arrangement that is an arrangement of two unit regions adjacent to the first arrangement and is used to output correction information for correcting the position information.

[0156] Accordingly, the first pattern 24 has a second arrangement that is an arrangement of two unit regions and is used to output correction information for correcting the position information. Therefore, when the first arrangement does not properly guide the light from the irradiation unit 18 to the light receiving unit 20 and the position information is incorrect, it is possible to use the correction information to correct the position information and suppress the reduction in detection accuracy.

[0157] In addition, the first pattern 24 has a plurality of first arrangements and a plurality of second arrangements respectively corresponding to the plurality of first arrangements.

[0158] Accordingly, it is possible to obtain correction information for each of the plurality of position information obtained based on the plurality of first arrangements. Therefore, no matter which of the plurality of position information is incorrect, it is possible to use the corresponding correction information for correction and suppress the reduction in detection accuracy.

[0159] Next, another example of the correction method of the correction unit 54 will be described.

[0160] Figure 13 is a diagram showing Figure 1 another example of the received light intensity of the light received by the light-receiving unit 20 of the encoder 10 shown Figure 13 (a) of FIG. is a diagram showing another example of the received light intensity of the light received by the first light-receiving member 48, Figure 13 (b) of FIG. is a diagram showing another example of the received light intensity of the light received by the second light-receiving member 50.

[0161] In the above description, the case where the correction unit 54 corrects the error of the output value based on the first arrangement using the output value based on the second arrangement is described, but it is not limited thereto. For example, the correction unit 54 may obtain the received light intensity of the light received by the first light-receiving member 48 and the received light intensity of the light received by the second light-receiving member 50, and use these obtained received light intensities to correct the error of the output value obtained based on the first arrangement.

[0162] Here, the following case is described: both the output value output from the fifth unit region from the head of the first arrangement based on the first pattern 24 and the output value output from the fifth unit region from the head of the first arrangement based on the second pattern 26 are "0", and the determination unit 52 determines that an error has occurred in one of these output values.

[0163] In this case, as Figure 13 shown, the correction unit 54 obtains the received light intensity of the light received by the first light-receiving member 48 from the fifth unit region from the head of the first arrangement based on the first pattern 24, and the received light intensity of the light received by the second light-receiving member 50 from the fifth unit region from the head of the first arrangement based on the second pattern 26. Then, the correction unit 54 compares the obtained received light intensities and corrects the error of the output value based on the comparison result. Specifically, the received light intensity of the light received by the first light-receiving member 48 is greater than the received light 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 "1", and keeps the output value of the second light-receiving member 50 in the state of "0" and outputs "0".

[0164] Next, a calculation circuit 88 for calculating values for forming a first pattern different from the first pattern 24 of the encoder 10 is described.

[0165] Figure 14 is a diagram showing Figure 1 the calculation circuit 88 for calculating values for forming a first pattern different from the first pattern 24 of the encoder 10 shown Figure 15 is a table showing the values obtained by Figure 14 the calculation circuit 88 shown

[0166] Figure 14 The calculation circuit 88 shown is for calculating based on the M code (irreducible polynomial): X 9 +X 5 +1 value circuit. By forming the first pattern based on the value obtained by the calculation circuit 88, it is possible to form a first pattern having a first arrangement and a second arrangement different from the first pattern 24.

[0167] As Figure 14 shown, the calculation circuit 88 has a plurality of registers 90 to 106 and a plurality of XOR circuits 108, 110.

[0168] The value output from the register 90 is input to the XOR circuit 108. The value output from the register 92 is input to the register 90. The value output from the register 94 is input to the register 92. The value output from the register 96 is input to the register 94. The value output from the register 98 is input to the XOR circuit 108 and the register 96. The value output from the register 100 is input to the register 98. The value output from the register 102 is input to the register 100. The value output from the register 104 is input to the register 102. The value output from the register 106 is input to the register 104.

[0169] The value output from the register 90 and the value output from the register 98 are input to the XOR circuit 108. The XOR circuit 108 calculates the exclusive OR of these two values and outputs the calculated value. The specified value input from the outside and the value output from the XOR circuit 108 are input to the XOR circuit 110. The XOR circuit 110 calculates the exclusive OR of these two values and outputs the calculated value. For example, the specified value is a predetermined value. The value output from the XOR circuit 110 is input to the register 106.

[0170] For example, when "0" is pre-stored in the registers 90, 94, 98, and 102 and "1" is pre-stored in the registers 92, 96, 100, 104, and 106, by repeatedly calculating the exclusive OR and outputting, the Figure 15 shown value is obtained.

[0171] By using the Figure 15 shown value, it is possible to form a first pattern having a first arrangement as an arrangement of 9 unit areas, a second arrangement as an arrangement of 4 unit areas, and a third arrangement as an arrangement of 1 unit area, and the third arrangement is used to output correction information for correcting the position information obtained based on the first arrangement. The third arrangement is adjacent to the first arrangement on the side opposite to the second arrangement.

[0172] For example, the output value output from the unit area at the head of the second arrangement is the value obtained by taking the exclusive OR of the two output values output from the unit area at the head of the first arrangement and the fifth unit area from the head. In addition, the output value output from the fourth unit area from the head of the second arrangement is the value obtained by taking the exclusive OR of the two output values output from the fourth unit area from the head of the first arrangement and the eighth unit area from the head. In addition, the output value output from the ninth unit area from the head of the first arrangement is the value obtained by taking the exclusive OR of the two output values output from the unit area at the head of the third arrangement and the fourth unit area from the head of the first arrangement. Due to having such a relationship, it is possible to correct the position information obtained based on the first arrangement using the correction information obtained based on the second arrangement and the correction information obtained based on the third arrangement.

[0173] (Other embodiments, etc.)

[0174] As described above, as an example of the technology disclosed in the present application, embodiments have been described. However, the technology based on the present disclosure is not limited to these, and can also be applied to embodiments or modified examples obtained by appropriately making changes, substitutions, additions, omissions, etc. within the scope not departing from the gist of the present disclosure.

[0175] In the above-described embodiment, the case where the encoder 10 includes the first pattern 24 and the second pattern 26 has been described, but it is not limited thereto. For example, the encoder 10 may not include the second pattern 26.

[0176] In this case, the encoder includes: a rotating plate 12 having the first pattern 24; an irradiation unit 18 that irradiates light to the first pattern 24; and a light receiving unit 20 that receives the light irradiated from the irradiation unit 18 and passing through the first pattern 24. The first pattern 24 has a structure in which the first unit area 32 and the second unit area 34 are arranged along the circumferential direction centered on the rotation axis A of the rotating plate 12. The first unit area 32 guides the light irradiated from the irradiation unit 18 to the light receiving unit 20, and the second unit area 34 does not guide the light irradiated from the irradiation unit 18 to the light receiving unit 20. When the first unit area 32 and the second unit area 34 are referred to as unit areas, the first pattern 24 has: a first arrangement that is an arrangement of 9 unit areas and is used to output position information indicating the position of the rotation axis 5; and a second arrangement that is an arrangement of 2 unit areas adjacent to the first arrangement and is used to output correction information for correcting the position information.

[0177] Accordingly, the first pattern 24 has a second arrangement that is an arrangement of two unit regions, and this second arrangement is used to output correction information for correcting the position information. Thus, in a case where the first arrangement does not properly guide the light from the irradiation unit 18 to the light receiving unit 20 and the position information is incorrect, the position information can be corrected using the correction information, and a reduction in detection accuracy can be suppressed.

[0178] In addition, in the above-described embodiment, a case where the detection target of the encoder 10 is the rotating shaft 5 has been described, but it is not limited thereto. For example, the detection target of the encoder 10 may not be the rotating shaft 5, as long as it is a rotating body.

[0179] In addition, in the above-described embodiment, a case where the first unit region 32 and the first unit region 40 transmit the light emitted from the irradiation unit 18 and guide the light to the light receiving unit 20 has been described, but it is not limited thereto. For example, the first unit region may also reflect the light emitted from the irradiation unit and guide the light to the light receiving unit. In this case, for example, the main body of the rotating plate is formed of SUS or the like, the first unit region is formed of chromium plating or the like that reflects light, and the second unit region is formed of black chromium plating or the like that does not reflect light.

[0180] In addition, in the above-described embodiment, a case where the second pattern 26 is provided at a position radially inside the first pattern 24 has been described, but it is not limited thereto. For example, the second pattern may also be provided at a position radially outside the first pattern.

[0181] In addition, in the above-described embodiment, a case where the first unit region 32 and the second unit region 42 corresponding to the first unit region 32 are adjacent to each other in the radial direction has been described, but it is not limited thereto. For example, the first unit region 32 and the second unit region 42 corresponding to the first unit region 32 may not be adjacent to each other in the radial direction, and may be provided at positions radially offset from each other.

[0182] In addition, in the above-described embodiment, a case where the second unit region 34 and the first unit region 40 corresponding to the second unit region 34 are adjacent to each other in the radial direction has been described, but it is not limited thereto. For example, the second unit region 34 and the first unit region 40 corresponding to the second unit region 34 may not be adjacent to each other in the radial direction, and may be provided at positions radially offset from each other.

[0183] In addition, in the above-described embodiment, the case where the first pattern 24 and the second pattern 26 are provided on the main surface on the first substrate 14 side of the main body 22 has been described, but it is not limited thereto. For example, it may be that the main body of the rotating plate is formed of a material that does not transmit light, and the first unit region is formed by a through hole that penetrates the main body of the rotating plate, thereby forming the first pattern and the second pattern. In this case, a part of the main body of the rotating plate becomes the second unit region.

[0184] In addition, in the above-described embodiment, the case where the first arrangement is an arrangement of 9 unit regions, the second arrangement is an arrangement of 2 or 4 unit regions, and the third arrangement is an arrangement of 1 unit region has been described, but it is not limited thereto.

[0185] Industrial Applicability

[0186] The encoder according to the present disclosure can be used in the rotation detection of a rotation shaft or the like of a motor for rotationally driving a load.

[0187] Description of Reference Numerals

[0188] 10: Encoder; 12: Rotating plate; 14: First substrate; 16: Second substrate; 18: Irradiation unit; 20: Light receiving unit; 22: Main body; 24: First pattern; 26: Second pattern; 28: First light guide unit; 30: First non-light guide unit; 32, 40: First unit region; 34, 42: Second unit region; 36: Second light guide unit; 38: Second non-light guide unit; 44: First light emitting unit; 46: Second light emitting unit; 48: First light receiving member; 50: Second light receiving member; 52: Determination unit; 54: Correction unit.

Claims

1. An encoder, comprising: A rotating plate configured to rotate in a rotating direction about a rotation axis, the rotating plate having a first pattern and a second pattern formed based on M-codes; An irradiation unit that irradiates light onto the first pattern and the second pattern; 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, wherein the first pattern and the second pattern have a structure in which a first unit area and a second unit area are arranged along a circumferential direction centered on the rotation axis of the rotating plate, the first unit area guides the light irradiated from the irradiation unit to the light receiving unit, and the second unit area does not guide the light irradiated from the irradiation unit to the light receiving unit, the first unit area and the second unit area in the first pattern are arranged in a direction perpendicular to the rotation direction opposite to the first unit area and the second unit area in the second pattern, wherein the encoder further comprises a determination unit, the light receiving unit has: a first light receiving member that receives the light irradiated from the irradiation unit and passing through the first pattern, and outputs the intensity of the received light after binarization; and a second light receiving member that receives the light irradiated from the irradiation unit and passing through the second pattern, and outputs the intensity of the received light after binarization, the second pattern is arranged such that the output value of the second light receiving member is a value opposite to the output value of the first light receiving member, in a case where the output value of the second light receiving member is not a value opposite to the output value of the first light receiving member, the determination unit determines that an error has occurred in either the output value of the first light receiving member or the output value of the second light receiving member, and outputs a determination result, the encoder further comprises a correction unit, in a case where the determination unit determines that an error has occurred in either the output value of the first light receiving member or the output value of the second light receiving member, the correction unit determines whether an error has occurred in the output value of the first light receiving member, and corrects the output value of the first light receiving member in a case where an error has occurred in the output value of the first light receiving member.

2. The encoder according to claim 1, wherein, When the first unit area and the second unit area are referred to as unit areas, the first pattern has: A first arrangement as an arrangement of M of the unit areas, the first arrangement being used to output position information indicating the position of a detection object; And A second arrangement adjacent to the first arrangement as an arrangement of N of the unit areas, the correction unit is configured to correct the position information based on the second arrangement in a case where the determination unit determines that an error has occurred in either the output value of the first light receiving member or the output value of the second light receiving member.

3. The encoder according to claim 1, wherein, When the first unit area and the second unit area are referred to as unit areas, the first pattern has: A first arrangement as an arrangement of M of the unit areas, the first arrangement being used to output position information indicating the position of a detection object; And A second arrangement that is adjacent to the first arrangement and is an arrangement of N of the unit regions, the second arrangement being configured to output correction information for correcting the position information.

4. The encoder according to claim 2, wherein the first pattern has a plurality of the first arrangements and a plurality of the second arrangements respectively corresponding to the plurality of the first arrangements.

5. The encoder according to claim 3, wherein the first pattern has a plurality of the first arrangements and a plurality of the second arrangements respectively corresponding to the plurality of the first arrangements.

6. An encoder, comprising: a rotating plate having a pattern; an irradiation unit that irradiates light onto the pattern; and a light receiving unit that receives the light irradiated from the irradiation unit and passing through the pattern, Among them, the pattern having a structure in which a first unit region and a second unit region are arranged along a circumferential direction centered on a rotation axis of the rotating plate, the first unit region guiding the light irradiated from the irradiation unit to the light receiving unit, and the second unit region not guiding the light irradiated from the irradiation unit to the light receiving unit, when the first unit region and the second unit region are referred to as unit regions, the pattern has: a first arrangement that is an arrangement of M of the unit regions, the first arrangement being configured to output position information indicating the position of a detection target; and a second arrangement that is adjacent to the first arrangement and is an arrangement of N of the unit regions, the second arrangement being configured to output correction information for correcting the position information, wherein the pattern includes a first pattern and a second pattern formed based on M codes, and the first unit region and the second unit region in the first pattern are arranged in a direction perpendicular to the rotation direction opposite to the first unit region and the second unit region in the second pattern, wherein the encoder further includes a determination unit, the light receiving unit has: a first light receiving member that receives the light irradiated from the irradiation unit and passing through the first pattern, and outputs the intensity of the received light after binarization; and a second light receiving member that receives the light irradiated from the irradiation unit and passing through the second pattern, and outputs the intensity of the received light after binarization, the second pattern is arranged such that the output value of the second light receiving member is a value opposite to the output value of the first light receiving member, in a case where the output value of the second light receiving member is not a value opposite to the output value of the first light receiving member, the determination unit determines that an error has occurred in one of the output values of the first light receiving member and the second light receiving member, and outputs a determination result, the encoder further includes a correction unit that, in a case where the determination unit determines that an error has occurred in one of the output values of the first light receiving member and the second light receiving member, determines whether an error has occurred in the output value of the first light receiving member, and corrects the output value of the first light receiving member in a case where an error has occurred in the output value of the first light receiving member.

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