Rotary encoder

Abstract

A rotary encoder detects the rotation of a rotary disk (100) provided with an annular encoding pattern (110) by a detection unit (120), and calculates the rotation angle of the rotary disk (100) by an encoder processing unit (130), the encoding pattern (110) being composed of a first encoding pattern (111) and a second encoding pattern (112) which are concentric. The first code pattern (111) is configured from a plurality of first patterns having a first inclination with respect to the radial direction, and the second code pattern (112) is configured from a plurality of second patterns having a second inclination with respect to the radial direction, the second inclination being different from the first inclination. The encoder processing unit (130) determines the eccentricity of the encoding pattern (110) on the basis of the detection result of the first encoding pattern (111) obtained by the detection unit (120) and the detection result of the second encoding pattern (112) obtained by the detection unit (120), and corrects the rotation angle by the determined eccentricity.

Description

Technical Field

[0001] The invention relates to a rotary encoder. Background Art

[0002] There is an optical rotary encoder, which includes: a rotating disk provided with a slit; a detection unit having a light receiving and emitting unit; and an encoder processing unit that calculates the rotation angle of the rotating disk based on the detection result of the detection unit. It is known that in the case of this rotary encoder, when the rotation center of the rotating disk and the pattern center of the slit are eccentric and not accurately aligned, an error of one cycle (hereinafter referred to as "eccentric angle error") occurs during one rotation.

[0003] In the conventional rotary encoder, the coding pattern provided on the rotating disk is as follows: Fig. 9 As shown. Fig. 9 In the embodiment, a code pattern 110A is formed on a rotating disk 100A, and slits are formed in the code pattern 110A along the radial direction. In the case of such a code pattern 110A, eccentricity cannot be detected.

[0004] Therefore, in order to eliminate the above-mentioned eccentric angle error, Patent Document 1 proposes a method of arranging detection units at two positions facing each other across the rotation center of a rotating disk, thereby generating two angle data with a phase difference of 180 degrees, and averaging the two angle data.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 60-146113 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In the method of Patent Document 1, in order to generate two angle data with a phase difference of 180 degrees, it is necessary to accurately arrange two detection units at positions opposite to each other across the rotation center of the rotating disk. Since the detection units are arranged at two locations, there are problems such as an increase in the size of the rotary encoder, an increase in the number of parts leading to an increase in cost, and a deterioration in the installation workability due to the adjustment of the two detection units.

[0010] Therefore, a rotary encoder is desired that can accurately eliminate the eccentric angle error of one cycle per rotation contained in the angle data when calculating the rotation angle by optically detecting the encoding pattern of a rotating disk, without causing the device to be larger and the cost to increase, and without requiring troublesome adjustments.

[0011] An object of the present invention is to provide a rotary encoder that can eliminate an eccentric angle error when calculating a rotation angle by optically detecting a code pattern of a rotating disk without increasing the size of the device.

[0012] Solutions for solving problems

[0013] The rotary encoder of the present invention detects the rotation of a rotating disk provided with an annular coding pattern through a detection unit, and calculates the rotation angle of the rotating disk through an encoder processing unit, wherein the coding pattern is composed of a first coding pattern and a second coding pattern in the form of concentric circles, the first coding pattern is composed of a plurality of first patterns having a first inclination relative to a radial direction, and the second coding pattern is composed of a plurality of second patterns having a second inclination in a direction different from the first inclination relative to the radial direction, the encoder processing unit calculates the eccentricity of the coding pattern based on the detection result of the first coding pattern obtained by the detection unit and the detection result of the second coding pattern obtained by the detection unit, and corrects the rotation angle through the calculated eccentricity.

[0014] In the rotary encoder of the present invention, the first inclination and the second inclination are either: the first inclination is +45 degrees and the second inclination is -45 degrees; or the first inclination is -45 degrees and the second inclination is +45 degrees.

[0015] In the rotary encoder of the present invention, a plurality of first patterns constituting a first coding pattern and a plurality of second patterns constituting a second coding pattern are constituted by slits, and a detection unit comprises: a light source for irradiating light to the first coding pattern and the second coding pattern; a fixed slit for respectively shrinking the light from the light source that has passed through the first coding pattern and the light from the light source that has passed through the second coding pattern through an opening of a certain size; and a light receiving unit for detecting the light from the light source that has passed through the first coding pattern and the fixed slit, and detecting the light from the light source that has passed through the second coding pattern and the fixed slit.

[0016] In the rotary encoder of the present invention, the encoder processing unit includes: an angle data conversion unit, which generates angle data based on the detection result of the first coding pattern obtained by the detection unit and the detection result of the second coding pattern obtained by the detection unit; an eccentricity calculation unit, which calculates eccentricity data representing the eccentricity of the coding pattern based on the phase change of the detection result of the first coding pattern obtained by the detection unit and the detection result of the second coding pattern obtained by the detection unit; and a correction unit, which corrects the angle data based on the eccentricity data.

[0017] Effects of the Invention

[0018] According to the present invention, a rotary encoder can be provided, which, when optically detecting the coding pattern of a rotating disk to calculate the rotation angle, calculates the eccentricity of the coding pattern based on the detection results of the first coding pattern and the second coding pattern by the detection unit, and corrects the rotation angle by the calculated eccentricity. As a result, when optically detecting the coding pattern of the rotating disk to calculate the rotation angle, the eccentricity angle error can be eliminated without increasing the size of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram showing the structure of the encoding pattern provided on the rotating disk in the first embodiment.

[0020] Figure 2 1 is a structural diagram showing the structure of the rotary encoder in the first embodiment.

[0021] Figure 3 This is an explanatory diagram showing a change in the positional relationship between the code pattern of the rotating disk and the fixed slit of the detection unit due to eccentricity in the first embodiment.

[0022] Figure 4 This is an explanatory diagram showing the change in the positional relationship between the rotating disk and the encoding pattern due to eccentricity in the first embodiment.

[0023] Figure 5 This is an explanatory diagram showing the phase characteristics of the encoding pattern when eccentricity exists in Implementation Example 1.

[0024] Figure 6 This is an explanatory diagram showing a first arrangement example of the code pattern of the rotating disk and the fixed slits of the detection unit in the first embodiment.

[0025] Figure 7 This is an explanatory diagram showing a second arrangement example of the code pattern of the rotating disk and the fixed slits of the detection unit in the first embodiment.

[0026] Figure 8 This is an explanatory diagram showing other coding patterns in implementation mode 1.

[0027] Fig. 9 This is a diagram showing the structure of an encoding pattern provided on a rotating disk in a conventional rotary encoder. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the rotary encoder of the present invention will be described using the drawings. It should be noted that in each of the drawings, the same reference numerals are given to the same parts.

[0029] Implementation method 1.

[0030] First, refer to Figure 1 and Figure 2A basic structure of a rotary encoder 1 according to the first embodiment of the present invention will be described.

[0031] Figure 1 1 is a diagram showing the structure of the code pattern 110 provided on the rotating disk 100 in the first embodiment. Figure 2 1 is a structural diagram showing the structure of the rotary encoder 1 in the first embodiment.

[0032] [Structure of the rotary encoder 1]

[0033] First, refer to Figure 2 The structure of the rotary encoder 1 will be described.

[0034] The rotary encoder 1 is a device for calculating the rotation angle of the rotating body 10, and mainly includes a rotating disk 100, a rotating shaft 101, a detection unit 120, and an encoder processing unit 130. When calculating the rotation angle of the rotating body 10, the rotary encoder 1 performs correction to eliminate the eccentric angle error included in the angle data.

[0035] The rotating disk 100 is connected to the rotating body 10 via the rotating shaft 101. Therefore, the rotating disk 100 rotates at the same rotation speed as the rotating body 10. Figure 1 As shown, a coding pattern 110 composed of slits is formed on the rotating disk 100. The coding pattern 110 is composed of a first coding pattern 111 and a second coding pattern 112 in concentric circles.

[0036] The first coding pattern 111 is composed of a plurality of first patterns having a first inclination relative to the radial direction. Figure 1 As shown, the first coding pattern 111 is composed of a plurality of first pattern slits having an inclination of +45 degrees with respect to the radial direction.

[0037] The second coding pattern 112 is composed of a plurality of second patterns having a second inclination in a direction different from the first inclination relative to the radial direction. Figure 1 As shown, the second code pattern 112 is composed of a plurality of second pattern slits having an inclination of -45 degrees with respect to the radial direction.

[0038] In addition, the first pattern may be inclined in the opposite direction by -45 degrees, and the second pattern may be inclined in the opposite direction by +45 degrees. It should be noted that +45 degrees and -45 degrees are effective values ​​with the highest sensitivity for eccentricity detection, but are not limited to these angles. For example, a combination of an inclination in the range of +30 degrees to +60 degrees and an inclination in the range of -30 degrees to -60 degrees may also be used.

[0039] The detection unit 120 includes a light source 121 , a fixed slit 122 , and a light receiving unit 123 so as to sandwich the rotating disk 100 .

[0040] The detection unit 120 is a transmission type sensor that irradiates the code pattern 110 of the rotating disk 100 through the light source 121 and receives the transmission light transmitted through the code pattern 110 and the fixed slit 122 through the light receiving unit 123, thereby optically detecting the rotation of the rotating disk 100. It should be noted that, when a reflection type pattern is formed on the rotating disk 100 instead of the transmission type code pattern 110, a reflection type sensor can be used as the detection unit 120.

[0041] The light receiving unit 123 is composed of a plurality of units including a first light receiving unit 123 a corresponding to the first code pattern 111 and a second light receiving unit 123 b corresponding to the second code pattern 112 , with a light receiving element group consisting of a group of four light receiving elements as one unit.

[0042] Similarly, the fixed slit 122 is composed of a first fixed slit 122a corresponding to the first coding pattern 111 and the first light receiving portion 123a, and a second fixed slit 122b corresponding to the second coding pattern 112 and the second light receiving portion 123b. Here, the first fixed slit 122a is composed of a slit having the same inclination as the first pattern constituting the first coding pattern 111, for example, +45 degrees. The second fixed slit 122b is composed of a slit having the same inclination as the second pattern constituting the second coding pattern 112, for example, -45 degrees.

[0043] In the first light receiving unit 123a and the second light receiving unit 123b, the four light receiving elements constituting the light receiving element group are assigned a+, a-, b+, and b-. By adding and subtracting the signals from each of the light receiving elements a+, a-, b+, and b-, a light receiving signal for calculating the angle data of two phases with different phases can be obtained.

[0044] The encoder processing unit 130 includes an angle data conversion unit 131, an eccentricity calculation unit 132, and a correction unit 133. The angle data conversion unit 131 processes the two-phase light receiving signals from the light receiving unit 123 to calculate first angle data P1 based on the first code pattern 111 and second angle data P2 based on the second code pattern 112.

[0045] The eccentricity calculation unit 132 calculates the eccentricity angle error based on the phase difference between the first angle data P1 and the second angle data P2 and the phase characteristics described later. The correction unit 133 calculates and outputs the rotation angle θ of the rotating disk 100 in which the eccentricity angle error is eliminated based on the eccentricity angle error and the first angle data P1 and the second angle data P2. The correction unit 133 may also have a communication function to output the rotation angle θ to an external device.

[0046] [Specific example of eccentricity]

[0047] Below, refer to Figure 3 and Figure 4 , the positional relationship between the coding pattern 110 and the fixed slit 122 corresponding to the eccentricity is described.

[0048] Figure 3 This is an explanatory diagram showing a change in the positional relationship between the code pattern 110 of the rotating disk 100 and the fixed slit 122 of the detection unit 120 due to eccentricity in the first embodiment. Figure 4 This is an explanatory diagram showing a change in the positional relationship between the rotating disk 100 and the code pattern 110 due to eccentricity in the first embodiment.

[0049] exist Figure 3 In Figure 1 As shown, the code pattern 110 is composed of a first code pattern 111 on the inner circumference side of the rotating disk 100 and a second code pattern 112 on the outer circumference side.

[0050] The fixed slits 122 are composed of a first fixed slit 122 a corresponding to the first code pattern 111 on the inner peripheral side and a second fixed slit 122 b corresponding to the second code pattern 112 on the outer peripheral side.

[0051] exist Figure 3 In FIG. 1 , it is assumed that the turntable 100 rotates in the counterclockwise direction. Figure 3 In FIG. 1 , for convenience of explaining the influence of eccentricity, the positions of the first code pattern 111 , the first fixed slit 122 a , the second code pattern 112 , and the second fixed slit 122 b are shown based on the timing when the two components are aligned without eccentricity.

[0052] Figure 3 (a) shows the positional relationship between the first code pattern 111 and the first fixed slit 122a, and between the second code pattern 112 and the second fixed slit 122b at a specific timing when there is no eccentricity between the rotating disk 100 and the code pattern 110.

[0053] In this Figure 3 In the case of (a), even if the rotating disk 100 rotates, the first code pattern 111 and the first fixed slit 122a and the second code pattern 112 and the second fixed slit 122b continue to overlap with the same phase.

[0054] Figure 3 (b1)~ Figure 3(b8) represents the positional relationship between the first coding pattern 111 and the first fixed slit 122a and the second coding pattern 112 and the second fixed slit 122b in the eccentric states of 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees and 315 degrees when the + direction of the X axis of the XY plane is set to 0 degrees, the + direction of the Y axis is set to 90 degrees, and the offset direction of the coding pattern 110 relative to the rotation center of the rotating disk 100 is set to eccentricity. Figure 3 (b1)~ Figure 3 The phase in (b8) is expressed in Figure 3 (a) The state under the same specific timing. Figure 3 (b1)~ Figure 3 In (b8), the hollow arrow indicates the eccentric direction.

[0055] Figure 4 (b1)~ Figure 4 (b8) schematically shows the eccentric states in the directions of 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees and 315 degrees when the + direction of the X axis of the XY plane is set to 0 degrees, the + direction of the Y axis is set to 90 degrees, and the position of the detection unit 120 is set to 0 degrees.

[0056] The following describes a situation where the first coded pattern 111 and the first fixed slit 122a, and the second coded pattern 112 and the second fixed slit 122b overlap at different timings due to eccentricity. Here, since the rotating disk 100 rotates counterclockwise, if the first coded pattern 111 is located above the first fixed slit 122a, it means that the phase is advanced, if the first coded pattern 111 is located below the first fixed slit 122a, it means that the phase is delayed, and if the first coded pattern 111 overlaps with the first fixed slit 122a, it means that the phase is consistent. Similarly, since the rotating disk 100 rotates counterclockwise, if the second coded pattern 112 is located above the second fixed slit 122b, it means that the phase is advanced, if the second coded pattern 112 is located below the second fixed slit 122b, it means that the phase is delayed, and if the second coded pattern 112 overlaps with the second fixed slit 122b, it means that the phase is consistent.

[0057] exist Figure 3 In (b1), due to the eccentricity in the 0 degree direction (refer to Figure 4 In (b1)), the first coding pattern 111 is in a phase-delayed state relative to the first fixed slit 122a, and the second coding pattern 112 is in a phase-advanced state relative to the second fixed slit 122b.

[0058] exist Figure 3In (b2), due to the eccentricity of 45 degrees (refer to Figure 4 In (b2)), the first coding pattern 111 is consistent with the first fixed slit 122a, and the second coding pattern 112 is in a state of further phase advancement relative to the second fixed slit 122b.

[0059] exist Figure 3 In (b3), due to the 90 degree eccentricity (refer to Figure 4 In (b3)), the first coding pattern 111 is in a phase-advanced state relative to the first fixed slot 122a, and the second coding pattern 112 is in a phase-advanced state relative to the second fixed slot 122b.

[0060] exist Figure 3 In (b4), due to the eccentricity in the 135 degree direction (refer to Figure 4 In (b4)), the first coding pattern 111 is in a state of further phase advancement relative to the first fixed slit 122a, and the second coding pattern 112 is in a state of being consistent with the first fixed slit 122a.

[0061] exist Figure 3 In (b5), due to the 180 degree eccentricity (refer to Figure 4 In (b5)), the first coding pattern 111 is in a phase-advanced state relative to the first fixed slit 122a, and the second coding pattern 112 is in a phase-delayed state relative to the second fixed slit 122b.

[0062] exist Figure 3 In (b6), due to the eccentricity in the 225 degree direction (refer to Figure 4 In (b6)), the first coding pattern 111 is consistent with the first fixed slit 122a, and the second coding pattern 112 is further phase-delayed relative to the second fixed slit 122b.

[0063] exist Figure 3 In (b7), due to the eccentricity of 270 degrees (refer to Figure 4 In (b7)), the first coding pattern 111 is in a phase-delayed state relative to the first fixed slit 122a, and the second coding pattern 112 is in a phase-delayed state relative to the second fixed slit 122b.

[0064] exist Figure 3 In (b8), due to the eccentricity in the 315 degree direction (refer to Figure 4 In (b8)), the first coding pattern 111 is further phase-delayed relative to the first fixed slit 122a, and the second coding pattern 112 is aligned with the second fixed slit 122b.

[0065] That is, Figure 3 (b1)~ Figure 3 As shown in (b8), between the coding pattern 110 having an inclination and the eccentricity direction, the following phase characteristics of the coding pattern when eccentricity exists are generated.

[0066] The first code pattern 111 with an inclination of +45 degrees is in phase with the first fixed slit 122a at eccentricities of 45 degrees and 225 degrees parallel to the inclination, and no offset occurs (no eccentricity detection sensitivity). The first code pattern 111 with an inclination of +45 degrees is in a state where the phase offset with the first fixed slit 122a is the largest at eccentricities of 135 degrees and 315 degrees orthogonal to the inclination, and eccentricity can be detected with maximum sensitivity.

[0067] The second code pattern 112 with an inclination of -45 degrees is in phase with the second fixed slit 122b at 135 degrees and 315 degrees eccentricities parallel to the inclination, and no offset occurs (no eccentricity detection sensitivity). The second code pattern 112 with an inclination of -45 degrees is in a state where the phase offset with the second fixed slit 122b is the largest at 45 degrees and 225 degrees eccentricities orthogonal to the inclination, and eccentricity can be detected with maximum sensitivity.

[0068] Therefore, by combining the first code pattern 111 having an inclination of +45 degrees and the second code pattern 112 having an inclination of −45 degrees, it is possible to detect eccentric components in each direction of 360 degrees.

[0069] If we calculate continuously at a more detailed angle Figure 3 (b1)~ Figure 3 The phase characteristics of the coding pattern when there is eccentricity as shown in (b8) can be obtained Figure 5 That phase characteristic. Figure 5 : is an explanatory diagram showing the phase characteristics of the coding pattern when there is eccentricity in Embodiment 1. Figure 3 (b1)~ Figure 3 As described in (b8) of FIG. 1 , the phase characteristic of the first coding pattern 111 and the phase characteristic of the second coding pattern 112 are obtained in a state where they have a phase difference of 90 degrees.

[0070] [Processing of the encoder processing unit]

[0071] Hereinafter, when the encoder pattern 110 of the rotating disk 100 is optically detected to calculate the rotation angle, a process of the encoder processing unit 130 for eliminating the eccentric angle error included in the detected angle will be described.

[0072] In the encoder processing unit 130, the angle data conversion unit 131 receives light passing through the first encoding pattern 111 and the first fixed slit 122a through the first light receiving unit 123a and calculates the first angle data P1, and receives light passing through the second encoding pattern 112 and the second fixed slit 122b through the second light receiving unit 123b and calculates the second angle data P2.

[0073] The eccentricity calculation unit 132 obtains the phase difference between the first angle data P1 and the second angle data P2 calculated by the angle data conversion unit 131, and compares the phase difference with the Figure 5 The angle and amplitude of the eccentricity are obtained by comparing the phase characteristics obtained in advance with those shown in FIG.

[0074] The eccentricity calculation unit 132 calculates the eccentricity angle error at each angle of one rotation based on the eccentricity angle and amplitude, and supplies the calculated eccentricity angle error to the correction unit 133 .

[0075] The correction section 133 uses the first angle data P1 and the second angle data P2 from the angle data conversion section 131 and the eccentricity angle error from the eccentricity calculation section 132 to output data of the rotation angle that is not affected by the eccentricity angle error.

[0076] The rotary encoder 1 of embodiment 1 uses a concentric first coding pattern 111 and a second coding pattern 112 as the coding pattern 110, and optically detects the first coding pattern 111 and the second coding pattern 112 through a single detection unit 120. Therefore, compared with the encoder using two detection units shown in patent document 1, the device can be miniaturized and can be easily set up without complicated adjustments.

[0077] [Configuration example of coding pattern and fixed slit (1)]

[0078] Below, refer to Figure 6 , a specific example of the configuration of the first coding pattern 111 and the second coding pattern 112 and the first fixed slit 122a and the second fixed slit 122b will be described. Figure 6 This is an explanatory diagram showing a first arrangement example of the code pattern 110 of the rotating disk 100 and the fixed slits 122 of the detection unit 120 in the first embodiment.

[0079] exist Figure 6 , a specific example is shown in which the first fixed slit 122a and the second fixed slit 122b are each composed of four slits.

[0080] The first fixed slits 122a are arranged at an angle and interval corresponding to the first pattern constituting the first coding pattern 111. Furthermore, the first light receiving portion 123a is arranged corresponding to the first fixed slits 122a. Light from the light source 121 is transmitted through the first coding pattern 111 and the first fixed slits 122a and is received by the first light receiving portion 123a.

[0081] The second fixed slits 122b are arranged at an angle and interval corresponding to the second pattern constituting the second coding pattern 112. Furthermore, the second light receiving portion 123b is arranged corresponding to the second fixed slits 122b. The light from the light source 121 that has passed through the second coding pattern 112 and the second fixed slits 122b is received by the second light receiving portion 123b.

[0082] The first light receiving unit 123a and the second light receiving unit 123b are each composed of a group of four light receiving elements. The four light receiving elements are assigned a+, a-, b+, and b-. By adding and subtracting the signals from each of the light receiving elements of a+, a-, b+, and b-, a light receiving signal for calculating the angle data of two phases with different phases can be obtained.

[0083] It should be noted that the difference in circumferential position between the first coding pattern 111 and the second coding pattern 112, the difference in circumferential position between the first coding pattern 111 and the first fixed slit 122a, and the difference in circumferential position between the second coding pattern 112 and the second fixed slit 122b can be arbitrarily determined corresponding to the processing in the encoder processing unit 130.

[0084] [Configuration example of coding pattern and fixed slit (2)]

[0085] Below, refer to Figure 7 , a second specific example of the configuration of the first coding pattern 111 and the second coding pattern 112 and the first fixed slit 122a and the second fixed slit 122b will be described. Figure 7 This is an explanatory diagram showing a second arrangement example of the code pattern 110 of the rotating disk 100 and the fixed slits 122 of the detection unit 120 in the first embodiment.

[0086] exist Figure 7 In the embodiment, the first fixed slit 122a is composed of an eleventh fixed slit 122a1 and a twelfth fixed slit 122a2, wherein the eleventh fixed slit 122a1 is composed of four slits, and the twelfth fixed slit 122a2 is composed of four slits.

[0087] The eleventh fixed slit 122a1 and the twelfth fixed slit 122a2 are arranged at the same radial position and different circumferential positions. The eleventh fixed slit 122a1 and the twelfth fixed slit 122a2 are provided at an angle and interval corresponding to the first pattern constituting the first code pattern 111.

[0088] Furthermore, the eleventh light receiving portion 123a1 is provided corresponding to the eleventh fixed slit 122a1, and the twelfth light receiving portion 123a2 is provided corresponding to the twelfth fixed slit 122a2.

[0089] Light from the light source 121 is transmitted through the first code pattern 111 and the eleventh fixed slit 122a1 to be received by the eleventh light receiving portion 123a1, and is transmitted through the first code pattern 111 and the twelfth fixed slit 122a2 to be received by the twelfth light receiving portion 123a2.

[0090] exist Figure 7 In the embodiment, the second fixed slit 122b is composed of a twenty-first fixed slit 122b1 and a twenty-second fixed slit 122b2, wherein the twenty-first fixed slit 122b1 is composed of four slits, and the twenty-second fixed slit 122b2 is composed of four slits.

[0091] The twenty-first fixed slit 122b1 and the twenty-second fixed slit 122b2 are arranged at the same radial position and different circumferential positions. The twenty-first fixed slit 122b1 and the twenty-second fixed slit 122b2 are provided at an angle and interval corresponding to the second pattern constituting the second code pattern 112 .

[0092] Furthermore, the twenty-first light receiving portion 123 b 1 is provided corresponding to the twenty-first fixed slit 122 b 1 , and the twenty-second light receiving portion 123 b 2 is provided corresponding to the twenty-second fixed slit 122 b 2 .

[0093] The light from the light source 121 is transmitted through the second code pattern 112 and the twenty-first fixed slit 122b1 to be received by the twenty-first light receiving portion 123b1, and is transmitted through the second code pattern 112 and the twenty-second fixed slit 122b2 to be received by the twenty-second light receiving portion 123b2.

[0094] The eleventh light receiving unit 123a1, the twelfth light receiving unit 123a2, the twenty-first light receiving unit 123b1, and the twenty-second light receiving unit 123b2 are each composed of a group of four light receiving elements. The four light receiving elements are assigned a+, a-, b+, and b-. By adding and subtracting the signals from each of the light receiving elements of a+, a-, b+, and b-, a light receiving signal for calculating the angle data of two phases with different phases can be obtained.

[0095] It should be noted that the difference in circumferential position between the first coding pattern 111 and the eleventh fixed slit 122a1, the difference in circumferential position between the first coding pattern 111 and the twelfth fixed slit 122a2, the difference in circumferential position between the second coding pattern 112 and the twenty-first fixed slit 122b1, and the difference in circumferential position between the second coding pattern 112 and the twenty-second fixed slit 122b2 can be arbitrarily determined corresponding to the processing in the encoder processing unit 130.

[0096] [Another example of a coding pattern]

[0097] Below, refer to Figure 8 As another example of the coding pattern 110, a quadruple coding pattern 1100 is described. Figure 8 This is an explanatory diagram showing another coding pattern 1100 in embodiment 1.

[0098] The coding pattern 1100 is a pattern obtained by further doubling the double coding pattern 110 and placing it on the rotating disk 100. That is, the coding pattern 1100 is composed of an inner coding pattern 1101 and an outer coding pattern 1102. The inner coding pattern 1101 is provided with an inner first coding pattern 11011 and an inner second coding pattern 11012. The outer coding pattern 1102 is provided with an outer first coding pattern 11021 and an outer second coding pattern 11022.

[0099] In this case, the following are respectively set corresponding to the quadruple coding pattern 1100: Figure 6 or Figure 7 The fixed slit and light receiving part shown are sufficient.

[0100] The encoder processing unit 130 can correct the eccentricity angle error based on the eccentricity obtained by averaging the eccentricity obtained from the inner circumference coding pattern 1101 and the eccentricity obtained from the outer circumference coding pattern 1102. In addition, the encoder processing unit 130 can also correct the eccentricity angle error by averaging the eccentricity angle error calculated based on the eccentricity obtained from the inner circumference coding pattern 1101 and the eccentricity angle error calculated based on the eccentricity obtained from the outer circumference coding pattern 1102.

[0101] [Effects of Embodiment]

[0102] (1) The rotary encoder 1 of embodiment 1 detects the rotation of a rotating disk 100 having an annular coding pattern 110 by means of a detection unit 120, and calculates the rotation angle of the rotating disk 100 by means of an encoder processing unit 130, wherein the coding pattern 110 is composed of a first coding pattern 111 and a second coding pattern 112 in the form of concentric circles, the first coding pattern 111 is composed of a plurality of first patterns having a first inclination relative to a radial direction, and the second coding pattern 112 is composed of a plurality of second patterns having a second inclination relative to the radial direction in a direction different from the first inclination, the encoder processing unit 130 calculates the eccentricity of the coding pattern 110 based on the detection results of the first coding pattern 111 obtained by the detection unit 120 and the detection results of the second coding pattern 112 obtained by the detection unit 120, and corrects the rotation angle by means of the calculated eccentricity.

[0103] Thus, when the code pattern 110 of the rotating disk 100 is optically detected to calculate the rotation angle, an eccentric angle error can be eliminated without increasing the size of the device.

[0104] (2) In the rotary encoder 1 of the above (1) of the first embodiment, the first inclination and the second inclination are any of the following: the first inclination is +45 degrees and the second inclination is -45 degrees; or the first inclination is -45 degrees and the second inclination is +45 degrees. Here, when the first coding pattern 111 has an inclination of +45 degrees, it has the maximum sensitivity in the eccentricity of the 135 degree direction and the 315 degree direction orthogonal to +45 degrees, and has no sensitivity in the eccentricity of the 45 degree direction and the 225 degree direction parallel to +45 degrees. When the second coding pattern 112 has an inclination of -45 degrees, it has the maximum sensitivity in the eccentricity of the 45 degree direction and the 225 degree direction orthogonal to -45 degrees, and has no sensitivity in the eccentricity of the 135 degree direction and the 315 degree direction parallel to -45 degrees. Therefore, by combining the first code pattern 111 having an inclination of +45 degrees and the second code pattern 112 having an inclination of −45 degrees, it is possible to detect eccentric components in each direction of 360 degrees.

[0105] (3) In the rotary encoder 1 of (1) or (2) of the first embodiment, the plurality of first patterns constituting the first code pattern 111 and the plurality of second patterns constituting the second code pattern 112 are constituted by slits. The detection unit 120 includes: a light source 121 for irradiating light to the first code pattern 111 and the second code pattern 112; a fixed slit 122 for respectively contracting the light from the light source 121 that has passed through the first code pattern 111 and the light from the light source 121 that has passed through the second code pattern 112 through an opening of a certain size; and a light receiving unit 123 for detecting the light from the light source 121 that has passed through the first code pattern 111 and the fixed slit 122, and detecting the light from the light source 121 that has passed through the second code pattern 112 and the fixed slit 122. Therefore, according to the positional relationship between the first coding pattern 111 and the second coding pattern 112 with different inclinations and the fixed slit 122, the eccentricity can be optically detected, and the eccentricity angle error can be eliminated when the rotation angle is calculated by optically detecting the coding pattern 110 of the rotating disk 100 without increasing the size of the device.

[0106] (4) In the rotary encoder 1 of any one of (1) to (3) in the first embodiment, the encoder processing unit 130 includes: an angle data conversion unit 131 that generates angle data based on the detection result of the first code pattern 111 obtained by the detection unit 120 and the detection result of the second code pattern 112 obtained by the detection unit 120; an eccentricity calculation unit 132 that calculates eccentricity data indicating the eccentricity of the code pattern 110 based on the phase change of the detection result of the first code pattern 111 obtained by the detection unit 120 and the detection result of the second code pattern 112 obtained by the detection unit 120; and a correction unit 133 that corrects the angle data based on the eccentricity data. Thus, when the code pattern 110 of the rotating disk 100 is optically detected based on the detection result of the first code pattern 111 and the detection result of the second code pattern 112 to calculate the rotation angle, the eccentricity angle error can be eliminated.

[0107] Description of Reference Numerals

[0108] 1: rotary encoder; 10: rotating body; 100: rotating disk; 101: rotating shaft; 110: coding pattern; 111: first coding pattern; 112: second coding pattern; 120: detecting unit; 121: light source; 122: fixed slit; 122a: first fixed slit; 122a1: eleventh fixed slit; 122a2: twelfth fixed slit; 122b: second fixed slit; 122b1: twenty-first fixed slit; 122b2: twenty-second fixed slit; 123: light receiving unit; 123a: first light receiving unit; 123a1: eleventh light receiving unit; 123a2: twelfth light receiving unit; 123b: second light receiving unit; 123b1: twenty-first light receiving unit; 123b2: twenty-second light receiving unit; 130: encoder processing unit; 131: angle data conversion unit; 132: eccentricity calculation unit; 133: correction unit; 1100: coding pattern; 1101: inner side coding pattern; 1102: outer side coding pattern; 11011: first inner side coding pattern; 11012: second inner side coding pattern; 11021: first outer side coding pattern; 11022: second outer side coding pattern; θ: rotation angle.

Claims

1. A rotary encoder (1), which detects the rotation of a rotating disk (100) provided with an annular encoding pattern (110) by a detection unit (120), and calculates the rotation angle of the rotating disk (100) by an encoder processing unit (130), wherein: The coding pattern (110) is composed of a first coding pattern (111) and a second coding pattern (112) in the form of concentric circles. The first coding pattern (111) is composed of a plurality of first patterns having a first inclination relative to a radial direction, The second coding pattern (112) is composed of a plurality of second patterns having a second inclination with respect to the radial direction in a direction different from the first inclination. The encoder processing unit (130) calculates the eccentricity of the coding pattern (110) based on the detection result of the first coding pattern (111) obtained by the detection unit (120) and the detection result of the second coding pattern (112) obtained by the detection unit (120), and corrects the rotation angle by the eccentricity.

2. The rotary encoder according to claim 1, wherein: The first inclination and the second inclination are any one of the following: The first inclination is +45 degrees, and the second inclination is -45 degrees; or The first inclination is -45 degrees, and the second inclination is +45 degrees.

3. The rotary encoder according to claim 1, wherein: The plurality of first patterns constituting the first coding pattern (111) and the plurality of second patterns constituting the second coding pattern (112) are formed by slits, The detection unit (120) comprises: A light source (121) irradiates light toward the first coding pattern (111) and the second coding pattern (112); A fixed slit (122) is used to shrink the light from the light source that passes through the first coding pattern (111) and the light from the light source that passes through the second coding pattern (112) through an opening of a certain size; and The light receiving unit (123) detects the light from the light source that has passed through the first coding pattern (111) and the fixed slit (122), and detects the light from the light source that has passed through the second coding pattern (112) and the fixed slit (122).

4. The rotary encoder according to any one of claims 1 to 3, wherein: The encoder processing unit (130) comprises: An angle data conversion unit (131) generates angle data based on a detection result of the first coding pattern (111) obtained by the detection unit (120) and a detection result of the second coding pattern (112) obtained by the detection unit (120); an eccentricity calculation unit (132) for calculating eccentricity data indicating the eccentricity of the coding pattern (110) based on a phase change between a detection result of the first coding pattern (111) obtained by the detection unit (120) and a detection result of the second coding pattern (112) obtained by the detection unit (120); and A correction unit (133) corrects the angle data based on the eccentricity data.

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