Encoder device

Abstract

An encoder device detects rotation of a rotating disk (120) provided with a slit (130) by an encoder detection section (140) and calculates a rotation angle of the rotating disk (120) by an encoder processing section (150), wherein the encoder detection section (140) has a plurality of light-receiving element groups required to generate angle data by a prescribed arrangement in a single light-receiving section (142), the encoder processing section (150) converts light-receiving signals obtained by the plurality of light-receiving element groups into angle data for one rotation, calculates an absolute value accuracy error of the angle data for one rotation from the angle data and arrangement information related to the arrangement, calculates a rotation angle using the absolute value accuracy error to correct the absolute accuracy of the angle data for one rotation, and outputs the calculated rotation angle to the outside, thereby eliminating the absolute value accuracy error.

Description

Technical Field

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

[0002] An optical encoder device includes a rotating disk with slits, an encoder detection unit having a light-receiving and emitting portion, and an encoder processing unit that calculates the rotation angle of the rotating disk based on the detection results of the encoder detection unit. It is known that in this encoder device, if the rotation center of the rotating disk is not accurately aligned with the center of the slit pattern, an error of one cycle (hereinafter referred to as absolute accuracy error) will occur per rotation.

[0003] To eliminate the above-mentioned absolute value accuracy error, Patent Document 1 proposes a method of arranging encoder detection units at two positions facing each other across the rotation center of a rotating disk, generating two angle data with a phase difference of 180°, and averaging the two angle data.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 60-146113 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In the method of Patent Document 1, in order to generate two pieces of angle data having a phase difference of 180°, it is necessary to accurately arrange two encoder detection units at positions facing each other across the rotation center of the rotating disk.

[0009] Since the encoder detection units are provided at two locations, there arise problems such as an increase in the size of the encoder device, an increase in the number of components leading to a cost increase, and a deterioration in installation workability due to the adjustment of the two encoder detection units.

[0010] Therefore, when the rotation of the slit of the rotating disk is optically detected to calculate the rotation angle,

[0011] There is a need for an encoder device that can be easily installed without requiring complicated adjustments and that can accurately eliminate the absolute value accuracy error of the angle data within one cycle per rotation without causing an increase in size or cost.

[0012] An object of the present invention is to eliminate an absolute value accuracy error included in the detected angle when optically detecting the rotation of a slit of a rotating disk to calculate the rotation angle, thereby miniaturizing an encoder device and facilitating installation.

[0013] Solutions for solving problems

[0014] The encoder device of the present invention detects the rotation of a rotating disk provided with a slit by an encoder detection unit, and calculates the rotation angle of the rotating disk by an encoder processing unit, wherein:

[0015] The encoder detection unit has a plurality of light receiving element groups required to generate angle data in a single light receiving unit through a predetermined arrangement.

[0016] The encoder processing unit converts the light-receiving signals obtained by the plurality of light-receiving element groups into angle data for one rotation, calculates the absolute value precision error of the angle data for one rotation based on the angle data and configuration information related to the configuration, uses the absolute value precision error to correct the absolute precision of the angle data for one rotation to calculate the rotation angle, and outputs the calculated rotation angle to the outside.

[0017] Effects of the Invention

[0018] According to the present invention, an encoder device can be provided that eliminates absolute value accuracy errors included in the detected angle when optically detecting the rotation of a slit of a rotating disk to calculate the rotation angle, thereby miniaturizing the device and facilitating installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a configuration diagram showing the circuit configuration of the encoder device in accordance with the first embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram showing the configuration of the main parts of the encoder device in the first embodiment of the present invention.

[0021] Figure 3 It is a schematic diagram showing the detailed structure of a light receiving unit in an embodiment of the present invention.

[0022] Figure 4 This is an explanatory diagram showing an optical radius from the rotation center of the rotating disk to the light receiving unit in the first embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram showing the configuration of the main parts of a conventional encoder device. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the encoder device of the present invention will be described using the accompanying drawings. In the drawings, the same reference numerals are used to denote the same components.

[0025] Implementation 1 First, refer to Figure 1 and Figure 2 The basic configuration of encoder device 100 according to Embodiment 1 of the present invention will be described. Figure 11 is a diagram showing a circuit configuration of encoder device 100 according to Embodiment 1 of the present invention. Figure 2 This is a schematic diagram showing the configuration of the main parts of encoder device 100 according to Embodiment 1 of the present invention.

[0026] [Structure of Encoder Device 100]

[0027] exist Figure 1 In the embodiment, encoder device 100 is a device for calculating the rotation angle of rotating body 1, and mainly includes a rotating shaft 110, a rotating disk 120, an encoder detection unit 140, and an encoder processing unit 150. In encoder device 100, when calculating the rotation angle of rotating body 1, the absolute value accuracy error included in the angle data is corrected.

[0028] like Figure 2 As shown, radial slits 130 are formed on the rotating disk 120. The rotating disk 120 is connected to the rotating body 1 via the rotating shaft 110. Therefore, the rotating disk 120 formed with the slits 130 rotates at the same rotation speed as the rotating body 1.

[0029] The encoder detection unit 140 includes a light emitting unit 141 and a light receiving unit 142, which sandwich the rotating disk 120. Therefore, the encoder detection unit 140 is a transmissive sensor in which the light emitting unit 141 illuminates the slits 130 of the rotating disk 120, and the light receiving unit 142 receives the light transmitted through the slits 130, thereby optically detecting the rotation of the rotating disk 120. It should be noted that if the rotating disk 120 has a reflective pattern instead of the slits 130, a reflective sensor can be used in the encoder detection unit 140.

[0030] The detailed structure of the light receiving unit 142 of the encoder detection unit 140 is shown in FIG. Figure 3 . Figure 3 This is a schematic diagram showing the detailed structure of light receiving unit 142 in Embodiment 1 of the present invention. In encoder detection unit 140, within a single light receiving unit 142, first light receiving unit 142A and second light receiving unit 142B are arranged at the same position in the circumferential direction of rotating disk 120, but at different positions in the radial direction of rotating disk 120.

[0031] The first light receiving unit 142A and the second light receiving unit 142B are each composed of a light receiving element group consisting of four light receiving elements. That is, a single light receiving unit 142 has a plurality of light receiving element groups required for generating angle data in a predetermined arrangement.

[0032] Here, the four light-receiving elements that make up the light-receiving element group are assigned a+, a-, b+, and b-. By adding and subtracting the signals from each of these light-receiving elements, two light-receiving signals with different phases can be obtained for calculating the phase angle data.

[0033] The encoder processing unit 150 includes an angle data conversion unit 151A, an angle data conversion unit 151B, an error calculation unit 152, a correction unit 153, and an output unit 154. The angle data conversion unit 151A performs computational processing on the two-phase light-receiving signals from the first light-receiving unit 142A to calculate the first angle data P1. The angle data conversion unit 151B performs computational processing on the two-phase light-receiving signals from the second light-receiving unit 142B to calculate the second angle data P2. It should be noted that a single angle data conversion unit can be switched at high speed to calculate the first angle data P1 and the second angle data P2. Furthermore, a level correction circuit can be configured at the inputs of the angle data conversion units 151A and 151B.

[0034] The error calculation unit 152 refers to the first angle data P1, the second angle data P2, and configuration information described later to calculate the absolute value accuracy error Δ1 for each rotation of the first angle data P1. The correction unit 153 subtracts the absolute value accuracy error Δ1 from the first angle data P1 to correct the absolute accuracy of the angle data for each rotation, and calculates the rotation angle θ of the rotating disk 120. The output unit 154 outputs the rotation angle θ of the rotating disk 120 to an external device. To output the rotation angle θ to the external device, the output unit 154 may also include a communication function.

[0035] [Processing of Encoder Device 100]

[0036] Next, a description will be given of a process for calculating the rotation angle θ by optically detecting the rotation of the slit 130 of the rotating disk 120 in the encoder device 100. The terms, parameters, or data used in calculating the rotation angle θ are as follows.

[0037] In encoder device 100, if the rotation center of rotating disk 120 does not coincide with the pattern center of slit 130, encoder detection unit 140 detects slit 130 rotating in a state that deviates from a true circle during one rotation. Therefore, the angle data calculated by encoder processing unit 150 contains an error of one cycle per rotation relative to the actual rotation angle θ. This error of one cycle per rotation is referred to as absolute accuracy error.

[0038] The parameters in Embodiment 1 are defined as follows.

[0039] The rotation angle of the rotating disk 120 without error is set to θ (rad),

[0040] The first angle data calculated by the angle data conversion unit 151A based on the light reception signal of the slit 130 in the first light receiving unit 142A is set to P1 (rad) = θ + Δ1.

[0041] The second angle data calculated by the angle data conversion unit 151B based on the light reception signal of the slit 130 in the second light receiving unit 142B is set to P2 (rad) = θ + Δ2.

[0042] The absolute value accuracy error included in the first angle data P1 is set to Δ1 (rad),

[0043] The absolute value accuracy error included in the second angle data P2 is assumed to be Δ2 (rad).

[0044] use Figure 4 A state in which the rotation center of the rotating disk 120 and the pattern center of the slit 130 do not coincide with each other will be described. Figure 4 This is an explanatory diagram showing the optical radius from the rotation center of the rotating disk 120 to the light receiving unit 142 as the arrangement information in the first embodiment of the present invention.

[0045] exist Figure 4 In the equation ( ), C1 is the rotation center of the rotating disk 120, and C2 is the pattern center of the slit 130. The distance from the rotation center C1 to the first light receiving portion 142A is defined as the optical radius r1, the distance from the rotation center C1 to the second light receiving portion 142B is defined as the optical radius r2, and the distance between the rotation center C1 of the rotating disk 120 and the pattern center C2 of the slit 130 is defined as the deviation δ.

[0046] Here, the optical radii r1 and r2 are configuration information related to the configuration of the plurality of light receiving element groups constituting the first light receiving unit 142A and the second light receiving unit 142B. It should be noted that the configuration information may also include information such as the distance and angle between the plurality of light receiving element groups.

[0047] The error calculation unit 152 calculates the absolute value accuracy error Δ1 in the following manner. Here, the absolute value accuracy error Δ1 can be expressed as,

[0048] Δ1=(δ / r1)·sinθ.

[0049] In addition, the absolute value accuracy error Δ2 can be expressed as,

[0050] Δ2=(δ / r2)·sinθ.

[0051] Arranging the two equations for the absolute value accuracy errors Δ1 and Δ2 above and eliminating sinθ, we get:

[0052] Δ1=(r2 / (r2-r1))·(Δ1-Δ2).

[0053] Then, using P1=θ+Δ1 and P2=θ+Δ2, eliminating Δ2 from the above equation for Δ1, we can express it as follows:

[0054] Δ1=(r2 / (r2-r1))·(P1-P2).

[0055] That is, the error calculation section 152 may calculate the absolute value accuracy error Δ1 using the first angle data P1 , the second angle data P2 , and the optical radii r1 and r2 .

[0056] Here, (r2 / (r2-r1)) in the equation for calculating Δ1 is a constant. Therefore, the error calculation unit 152 can quickly calculate the absolute value accuracy error Δ1 using the difference between the first angle data P1 and the second angle data P2 and the constant.

[0057] The correction unit 153 calculates the rotation angle θ as follows using the absolute value accuracy error Δ1 calculated by the error calculation unit 152 .

[0058] θ=P1-Δ1

[0059] Here, the correction unit 153 subtracts only Δ1 calculated by the error calculation unit 152 from the first angle data P1 calculated by the angle data conversion unit 151A, and thus can calculate the rotation angle θ at a high speed.

[0060] That is, the encoder processing unit 150 can use the first angle data P1 calculated based on the light receiving signal of the first light receiving unit 142A, the second angle data P2 calculated based on the light receiving signal of the second light receiving unit 142B, the optical radius r1 of the first light receiving unit 142A, and the optical radius r2 of the second light receiving unit 142B to calculate the rotation angle θ as follows.

[0061] θ=P1-Δ1=P1-(r2 / (r2-r1))·(P1-P2)

[0062] Here, since (r2 / (r2-r1)) is a constant, the rotation angle θ can be calculated at high speed and high accuracy based on the first angle data P1 and P2 and the constant.

[0063] [Structure and Operation of Comparative Example (Encoder Device 100A)]

[0064] Here, as a comparative example of the encoder device 100 according to the first embodiment, the configuration of a conventional encoder device 100A will be described. Figure 5 100A is a schematic diagram showing the configuration of the main parts of a conventional encoder device 100A.

[0065] exist Figure 5 In the embodiment, a rotating disk 120 having slits 130 is connected to a rotating body 1 to be detected via a rotating shaft 110 and rotates at the same speed as the rotating body 1. Two encoder detection units 140A and 140B, each including a light emitting unit and a light receiving unit, are provided at opposing positions across the rotation center of the rotating disk 120 to detect the passage and interruption of light by the slits 130 of the rotating rotating disk 120.

[0066] If the rotation center of rotating disk 120 does not coincide with the pattern center of slit 130, the absolute value accuracy error between the first angle data calculated based on the light signal from encoder detection unit 140A and the second angle data calculated based on the light signal from encoder detection unit 140B theoretically has a phase difference of 180°. Therefore, by averaging the first and second angle data, the absolute value accuracy error per cycle per rotation is canceled out.

[0067] As described above, the conventional encoder device 100A requires the encoder detection units 140A and 140B to be precisely positioned opposite each other across the rotation center of the rotating disk 120, resulting in an increase in the size of the encoder device 100. Furthermore, the need to provide the encoder detection units 140A and 140B increases costs due to the increased number of components. Furthermore, in order to offset absolute value accuracy errors through averaging, the positions of the two encoder detection units 140A and 140B must be carefully adjusted so that the phase difference between the absolute value accuracy error included in the first angle data and the absolute value accuracy error included in the second angle data is precisely 180°, which degrades installation workability.

[0068] [Comparison between Encoder Device 100 and Encoder Device 100A]

[0069] As described above, in the encoder device 100 of embodiment 1, when the rotation of the slit 130 of the rotating disk 120 is optically detected to calculate the rotation angle θ, compared with the existing encoder device 100A, since a single encoder detection unit 140 can be used, the device will not be enlarged or the cost will not increase. It can be easily set up without complicated adjustments, and the absolute value accuracy error contained in the detected angle data can be eliminated.

[0070] [Effects of the embodiment]

[0071] The encoder device 100 of embodiment 1 is a device in which the encoder detection unit 140 optically detects the slit 130 provided on the rotating disk 120, and the encoder processing unit 150 calculates the rotation angle θ of the rotating disk 120. The encoder detection unit 140 has a first light receiving unit 142A and a second light receiving unit 142B at different positions in the radial direction of the rotating disk 120. The encoder processing unit 150 sets the first angle data calculated by the angle data conversion unit 151A based on the light receiving signal of the slit 130 in the first light receiving unit 142A to P1=θ+Δ1, sets the second angle data calculated by the angle data conversion unit 151B based on the light receiving signal of the slit 130 in the second light receiving unit 142B to P2=θ+Δ2, sets the absolute value accuracy error contained in the first angle data P1 to Δ1, sets the absolute value accuracy error contained in the second angle data P2 to Δ2, sets the distance from the rotation center C1 to the first light receiving unit 142A to the optical radius r1, and sets the distance from the rotation center C1 to the second light receiving unit 142B to the optical radius r2, and calculates the rotation angle θ as θ=P1-Δ1=P1-(r2 / (r2-r1))·(P1-P2).

[0072] Here, because encoder device 100 optically detects the rotation of slit 130 of rotating disk 120 using a single encoder detection unit 140, thereby detecting a rotation angle θ with no absolute accuracy error, it can be miniaturized without increasing the size and cost of the device. Furthermore, because encoder device 100 optically detects the rotation of slit 130 of rotating disk 120 using a single encoder detection unit 140, thereby detecting a rotation angle θ with no absolute accuracy error, it eliminates the need for the complex adjustments required by conventional systems using two encoder detection units, thus enabling easy installation.

[0073] In the encoder device 100 of embodiment 1, the encoder processing unit 150 includes: an angle data conversion unit 151A for calculating first angle data P1 based on the detection result of the first light receiving unit 142A, an angle data conversion unit 151B for calculating second angle data P2 based on the detection result of the second light receiving unit 142B, an error calculation unit 152 for calculating the absolute value accuracy error Δ1, and a correction unit 153 for calculating the rotation angle θ by subtracting the absolute value accuracy error Δ1 from the first angle data P1. The error calculation unit 152 uses the absolute value accuracy error Δ1, the absolute value accuracy error Δ2, the optical radius r1, and the optical radius r2 to calculate the absolute value accuracy error Δ1 as Δ1=(r2 / (r2-r1))·(P1-P2), and the correction unit 153 calculates the rotation angle θ as θ=P1-Δ1. Here, the error calculation unit 152 can quickly calculate the absolute value accuracy error Δ1 using the difference between the first angle data P1 and the second angle data P2 and the constant (r2 / (r2-r1). Then, the correction unit 153 subtracts only the absolute value accuracy error Δ1 calculated by the error calculation unit 152 from the first angle data P1, thereby being able to quickly and accurately calculate the rotation angle θ.

[0074] [Other embodiments]

[0075] While the encoder detection unit 140 illustrates a specific example in which the first light receiving unit 142A and the second light receiving unit 142B are positioned at different radial positions relative to the rotating disk 120, this arrangement is not limited to this and various modifications are possible. Furthermore, by performing calculations corresponding to the modified arrangement, the absolute value accuracy error Δ1 can be calculated, thereby enabling the highly accurate calculation of the rotation angle θ.

[0076] In the encoder processing unit 150 , a specific example in which data is output from the output unit 154 is shown, but this may be replaced by a communication unit that communicates with an external device.

[0077] exist Figure 1 In the illustrated configuration of the encoder device 100 , the error calculation unit 152 in the encoder processing unit 150 may be divided into a subtraction unit that calculates (P1−P2) and a multiplication unit that calculates (r2 / (r2−r1))·(P1−P2).

[0078] In addition, it can also be, Figure 1 In the structure of the encoder device 100 shown, the error calculation unit 152 and the correction unit 153 in the encoder processing unit 150 are integrated, and the rotation angle θ is calculated once by the integrated calculation processing unit as θ=P1-(r2 / (r2-r1))·(P1-P2).

[0079] Description of Reference Numerals

[0080] 1: rotating body; 100: encoder device; 110: rotating shaft; 120: rotating disk; 130: slit; 140, 140A, 140B: encoder detection unit; 141: light-emitting unit; 142: light-receiving unit; 142A: first light-receiving unit (light-receiving element group); 142B: second light-receiving unit (light-receiving element group); 150: encoder processing unit; 151A: angle data conversion unit; 151B: angle data conversion unit; 152: error calculation unit; 153: correction unit; 154: output unit; C1: rotation center; C2: pattern center; r1: optical radius of the first light-receiving unit; r2: optical radius of the second light-receiving unit; δ: distance (deviation) between the rotation center and the pattern center; θ: rotation angle.

Claims

1. An encoder device, comprising: an encoder detecting unit (140) detecting the rotation of a rotating disk (120) provided with a slit (130), and an encoder processing unit (150) calculating the rotation angle of the rotating disk (120), wherein: The encoder detection unit (140) has a plurality of light receiving element groups required for generating angle data in a single light receiving unit (142) through a predetermined configuration. The encoder processing unit (150) converts the light receiving signals obtained by the plurality of light receiving element groups into angle data for one rotation, calculates an absolute value precision error of the angle data for one rotation based on the angle data and configuration information related to the configuration, corrects the absolute precision of the angle data for one rotation using the absolute value precision error to calculate the rotation angle, and outputs the calculated rotation angle to the outside. The slits are radial slits, The distance from the rotation center of the rotating disk to the first light receiving portion of the plurality of light receiving element groups is defined as an optical radius r1, and the distance from the rotation center of the rotating disk to the second light receiving portion of the plurality of light receiving element groups is defined as an optical radius r2. The configuration information related to the configuration is the optical radius r1 and r2, The angle data calculated based on the light reception signal of the slit in the first light receiving unit is referred to as P1. The angle data calculated based on the light reception signal of the slit in the second light receiving unit is referred to as P2. When the rotation angle is θ, the rotation angle θ is calculated as θ=P1-(r2 / (r2-r1))·(P1-P2).

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