Magnetic encoder device

Abstract

To provide a magnetic encoder device capable of outputting detection signals with minimal distortion. [Solution] A magnetic encoder device 100 for detecting the movement of a moving part 120, comprising a magnetic sensor 110 having a magnetic sensing surface 111 and a moving part 120 having a plurality of teeth 121 made of a magnetic material, wherein the electrical angle of the unevenness of the teeth 121 is θ, the distance between the magnetic sensing surface 111 and the teeth 121 that changes according to the electrical angle θ is L(θ), the magnetoresistance between the magnetic sensing surface 111 and the teeth 121 is Rm, the permeability of the teeth 121 is μ, the area of ​​the magnetic sensing surface 111 is S, the magnetomotive force of the magnetic sensor 110 is F, and the magnetic flux passing between the magnetic sensing surface 111 and the teeth 121 is φ, then the magnetoresistance Rm is Rm = L(θ) / (μ·S), the constants A, B, and C satisfy B>C>0, and the plurality of teeth 121 are configured in a shape that satisfies L(θ) = A / (B+C·sin(θ)).

Description

Technical Field

[0001] The present invention relates to a magnetic encoder device, and more particularly to a magnetic encoder device in consideration of the waveform of a detection signal.

Background Art

[0002] There exists a magnetic encoder device that detects the rotation of a gear or the movement of a rack gear by a magnetic sensor. This type of magnetic encoder device utilizes the magnetoresistance that changes with the distance between the detection surface of the magnetic sensor and the teeth, and detects the linear movement or rotation of the teeth by a detection signal based on the change in magnetic flux corresponding to the magnetoresistance. This type of encoder is proposed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0006] The present invention aims to provide a magnetic encoder device capable of outputting detection signals with minimal distortion. [Means for solving the problem]

[0007] The magnetic encoder device according to this invention comprises a magnetic sensor having a magnetic sensing surface and a movable part having a plurality of teeth made of a magnetic material, and detects the movement of the movable part, wherein the movable part has a plurality of teeth arranged in a straight line at equal intervals, the electrical angle of the unevenness of the teeth is θ, the distance between the magnetic sensing surface and the teeth that changes according to the electrical angle θ is L(θ), the magnetoresistance between the magnetic sensing surface and the teeth is Rm, the permeability of the teeth is μ, the area of ​​the magnetic sensing surface is S, the magnetomotive force of the magnetic sensor is F, and the magnetic sensing surface If the magnetic flux passing between the tooth is denoted as φ, then the magnetic resistance Rm is Rm = L(θ) / (μ·S), and the constants A, B, and C satisfy B>C>0. Multiple teeth are configured in a shape that satisfies L(θ) = A / (B+C·sin(θ)). The magnetic flux φ is φ = F / Rm = (F·μ·S) / L(θ) = (F·μ·S·(B+C·sin(θ))) / A, and if (F·μ·S·B / A) is a constant X and (F·μ·S·C / A) is a constant Y, then φ = X+Y·sin(θ) is satisfied.

[0008] In the magnetic encoder device according to this invention, the moving part is a rack gear having multiple teeth and capable of moving in a linear direction.

[0009] The magnetic encoder device according to this invention comprises a magnetic sensor having a magnetic sensing surface and a movable part having a plurality of teeth made of a magnetic material, and detects the movement of the movable part, wherein the movable part has a plurality of teeth arranged at equal angular intervals on the outer circumference of a ring, the electrical angle of the unevenness of the teeth is θ, the distance between the magnetic sensing surface and the teeth that changes according to the electrical angle θ is L(θ), the distance from the rotation center of the movable part to the magnetic sensing surface is M, the radius between the rotation center and the teeth that changes according to the electrical angle θ is r(θ), the magnetoresistance between the magnetic sensing surface and the teeth is Rm, the permeability of the teeth is μ, the area of ​​the magnetic sensing surface is S, the magnetomotive force of the magnetic sensor is F, and the magnetic flux passing between the magnetic sensing surface and the teeth is If we let φ be the case, the magnetic resistance Rm is Rm = L(θ) / (μ·S), and the constants A, B, and C satisfy B>C>0. Let N be the number of teeth, then L(θ) = Mr(θ), and from that, r(θ) = MA / (B+C·sin(N·θ)). The teeth are configured in a shape that satisfies L(θ) = M - (MA / (B+C·sin(N·θ)) = A / (B+C·sin(N·θ)). The magnetic flux φ is φ = F / Rm = (F·μ·S) / L(θ) = (F·μ·S·(B+C·sin(N·θ))) / A, and if (F·μ·S·B / A) is a constant X and (F·μ·S·C / A) is a constant Y, then φ = X + Y·sin(N·θ) is satisfied.

[0010] In the magnetic encoder device according to this invention, the moving part is a rotatable gear having multiple teeth.

[0011] In the magnetic encoder device according to this invention, the magnetic sensor outputs a sinusoidal detection signal corresponding to the magnetic flux φ. [Effects of the Invention]

[0012] According to the magnetic encoder device of this invention, the magnetic sensor detects magnetic flux having a component proportional to sin(θ) or sin(N·θ), making it possible to output a detection signal with less distortion based on the detected magnetic flux. [Brief explanation of the drawing]

[0013] [Figure 1]This is a configuration diagram showing the overall configuration of the magnetic encoder device in Embodiment 1. [Figure 2] This is an explanatory diagram showing an enlarged view of the main part of Figure 1. [Figure 3] This is a configuration diagram showing the overall configuration of the magnetic encoder device in Embodiment 2. [Figure 4] This is an explanatory diagram showing an enlarged view of the main part of Figure 3. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the magnetic encoder device of the present invention will be described with reference to the drawings. In each figure, the same parts are denoted by the same reference numerals.

[0015] Embodiment 1. First, the basic overall configuration of the magnetic encoder device 100 in Embodiment 1 will be described with reference to Figures 1 and 2. Figure 1 is a configuration diagram showing the overall configuration of the magnetic encoder device 100 in Embodiment 1. Figure 2 is an explanatory diagram showing an enlarged view of the main part of Figure 1.

[0016] [Configuration of Embodiment 1] The magnetic encoder device 100 of Embodiment 1 magnetically detects linear movement and mainly comprises a magnetic sensor 110 and a moving part 120.

[0017] The magnetic sensor 110 consists of a magnetic sensing surface 111 and a magnetic sensor body 112. The magnetic sensor body 112 includes a magnet and a magnetoresistive element. The magnetic sensor 110 outputs a detection signal corresponding to the magnetic flux passing through the magnetoresistive element.

[0018] The moving part 120 includes a plurality of teeth 121 and a base part 122, and is configured as a rack gear. The moving part 120 is configured to be movable in a linear direction in the longitudinal direction of the moving part 120 together with a measurement object (not shown). On the base part 122 of the moving part 120, a plurality of teeth 121 are arranged at equal intervals. The plurality of teeth 121 are made of a magnetic material. One cycle consisting of one crest and one trough included in the plurality of teeth 121 constitutes 0° to 360° or 0 to 2π of the electrical angle θ. The number of teeth of the plurality of teeth 121 is determined according to the resolution required by the magnetic encoder device 100. The base part 122 is held by a holding part (not shown) so as to be movable in a linear direction in the longitudinal direction of the base part 122. Note that the plurality of teeth 121 and the base part 122 may be integrally formed of a magnetic material, or may be formed of different materials.

[0019] [Movement Detection of Embodiment 1] In the magnetic encoder device 100, various parameters are defined as follows. Let the electrical angle of the unevenness of the plurality of teeth 121 be θ, the distance that changes according to the electrical angle θ between the magnetic detection surface 111 and the teeth 121 be L(θ), the magnetic resistance between the magnetic detection surface 111 and the teeth 121 be Rm [Ω], the magnetic permeability of the teeth 121 be μ [H / m], and the area of the magnetic detection surface 111 be S [m 2 , the magnetomotive force of the magnet in the magnetic sensor 110 (hereinafter, the magnetomotive force of the magnetic sensor 110) be F [A], and the magnetic flux passing between the magnetic detection surface 111 and the teeth 121 be φ [Wb].

[0020] The magnetic resistance Rm between the magnetic detection surface 111 and the teeth 121 is proportional to the distance L(θ) that changes according to the electrical angle θ between the magnetic detection surface 111 and the teeth 121, and is inversely proportional to the magnetic permeability μ of the teeth 121 and the area S of the magnetic detection surface 111. Therefore, Rm = L(θ) / (μ·S) can be expressed as. Here, it is assumed that A, B, and C are constants that satisfy B > C > 0. Regarding the distance L(θ) between the magnetic sensing surface 111 and the tooth 121, which changes according to the electrical angle θ, L(θ) = A / (B + C·sin(θ)) Multiple teeth 121 are formed in a shape that satisfies the following conditions.

[0021] Under these conditions, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is proportional to the magnetomotive force F within the magnetic sensor 110 and inversely proportional to the magnetic resistance Rm between the magnetic sensing surface 111 and the teeth 121. In other words, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is proportional to the magnetomotive force F of the magnetic sensor 110, the permeability μ of the teeth 121, and the area S of the magnetic sensing surface 111, and inversely proportional to the distance L(θ) between the magnetic sensing surface 111 and the teeth 121, which changes according to the electrical angle θ. Therefore, The magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is φ = F / Rm =(F·μ·S) / L(θ) =(F·μ·S·(B+C·sin(θ))) / A That is the case. Here, let (F·μ·S·B / A) be a constant X and (F·μ·S·C / A) be a constant Y. In this case, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is φ = X + Y·sin(θ) It satisfies the condition. As a result, the magnetic sensor 110, which detects the magnetic flux φ passing between the magnetic detection surface 111 and the teeth 121, detects a magnetic flux φ having a component proportional to sin(θ). Therefore, the magnetic sensor 110 can output a detection signal with a low-distortion waveform that has a sin(θ) shape corresponding to the magnetic flux φ.

[0022] [Effects of Embodiment 1] The magnetic encoder device 100 of Embodiment 1 can achieve the following effects. In the magnetic encoder device 100 of Embodiment 1, when detecting linear movement of a moving part 120 in which a plurality of teeth 121 are arranged linearly at equal intervals, if A, B, and C are constants satisfying B>C>0, then the distance L(θ) between the magnetic detection surface 111 and the teeth 121 that changes according to the electrical angle θ is... L(θ) = A / (B + C·sin(θ)) Multiple teeth 121 are configured in a shape that satisfies the following conditions. As a result, in the magnetic sensor 110, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is φ = X + Y·sin(θ) This satisfies the condition. As a result, the magnetic sensor 110 detects a magnetic flux having a component proportional to sin(θ). Therefore, the magnetic sensor 110 can output a detection signal with a waveform that has little distortion based on the magnetic flux φ which contains a component proportional to sin(θ).

[0023] In the magnetic encoder device 100 of Embodiment 1, the moving part 120 has a plurality of teeth 121 arranged at equal intervals and is configured as a rack gear that can move in the linear direction. As a result, in the magnetic encoder device 100, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 of the rack gear is φ = X + Y·sin(θ) This satisfies the requirements. Therefore, in response to the linear movement of the movable part 120 as a rack gear, the magnetic sensor 110 can output a detection signal with a waveform that has little distortion, based on the magnetic flux φ which includes a component proportional to sin(θ).

[0024] In the magnetic encoder device 100 of Embodiment 1, the magnetic sensor 110 detects the magnetic flux φ = X + Y·sin(θ) and can output a detection signal with a sinusoidal waveform and low distortion based on the magnetic flux φ which includes a component proportional to sin(θ).

[0025] Embodiment 2. Next, the basic overall configuration of the magnetic encoder device 100 in Embodiment 2 will be described with reference to Figures 3 and 4. Figure 3 is a configuration diagram showing the overall configuration of the magnetic encoder device 100 in Embodiment 2. Figure 4 is an explanatory diagram showing an enlarged view of the main part of Figure 3. In Figures 3 and 4, the same reference numerals are used for parts that are the same as those in Figures 1 and 2, minimizing redundant explanations, and focusing on the differences.

[0026] [Configuration of Embodiment 2] The magnetic encoder device 100 of Embodiment 2 magnetically detects movement in the rotational direction and mainly comprises a magnetic sensor 110 and a moving part 120.

[0027] The magnetic sensor 110 consists of a magnetic sensing surface 111 and a magnetic sensor body 112. The magnetic sensor body 112 includes a magnet and a magnetoresistive element. The magnetic sensor 110 outputs a detection signal corresponding to the magnetic flux φ passing through the magnetoresistive element.

[0028] The movable part 120 is configured as a gear having multiple teeth 121 and a rotating shaft 123. The movable part 120 is configured to rotate together with a measuring object (not shown) around the rotating shaft 123. The movable part 120 as a gear has multiple N teeth 121 arranged at equal angular intervals on the outer circumference of a ring. The multiple teeth 121 are made of a magnetic material. One cycle, consisting of one peak and one valley within the multiple teeth 121, constitutes an electrical angle θ of 0° to 360° or 0 to 2π. The number of teeth N in the multiple teeth 121 is determined according to the resolution required by the magnetic encoder device 100. The rotating shaft 123 is rotatably held by bearings or the like (not shown).

[0029] [Movement detection in Embodiment 2] In the magnetic encoder device 100, various parameters are defined as follows. Let θ be the electrical angle of the irregularities of the multiple teeth 121, L(θ) be the distance between the magnetic sensing surface 111 and the teeth 121 that changes according to the electrical angle θ, M be the distance from the rotation center O of the movable part 120 to the magnetic sensing surface 111, r(θ) be the radius between the rotation center O of the movable part 120 and the teeth 121 that changes according to the electrical angle θ, Rm[Ω] be the magnetic resistance between the magnetic sensing surface 111 and the teeth 121, μ[H / m] be the magnetic permeability of the teeth 121, and S[m] be the area of ​​the magnetic sensing surface 111. 2 Let F[A] be the magnetomotive force of the magnet inside the magnetic sensor 110 (hereinafter referred to as the magnetomotive force of the magnetic sensor 110), and let φ[Wb] be the magnetic flux passing between the magnetic sensing surface 111 and the teeth 121.

[0030] The magnetic resistance Rm between the magnetic sensing surface 111 and the teeth 121 is proportional to the distance L(θ) between the magnetic sensing surface 111 and the teeth 121, which changes according to the electrical angle θ, and is inversely proportional to the magnetic permeability μ of the teeth 121 and the area S of the magnetic sensing surface 111. Therefore, Rm = L(θ) / (μ·S) It can be expressed as follows. Here, A, B, and C are constants satisfying B>C>0. Regarding the distance L(θ) between the magnetic sensing surface 111 and the tooth 121, which changes according to the electrical angle θ, L(θ)=Mr(θ) from, r(θ) = MA / (B + C·sin(N·θ)) And, L(θ) = M - (MA / (B + C·sin(N·θ))) =A / (B+C·sin(N·θ)) Multiple teeth 121 are formed in a shape that satisfies the following conditions.

[0031] Under these conditions, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is proportional to the magnetomotive force F within the magnetic sensor 110 and inversely proportional to the magnetic resistance Rm between the magnetic sensing surface 111 and the teeth 121. In other words, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is proportional to the magnetomotive force F of the magnetic sensor 110, the permeability μ of the teeth 121, and the area S of the magnetic sensing surface 111, and inversely proportional to the distance L(θ) between the magnetic sensing surface 111 and the teeth 121, which changes according to the electrical angle θ. Therefore, The magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is φ = F / Rm =(F·μ·S) / L(θ) =(F·μ·S·(B+C·sin(N·θ))) / A That is the case. Here, let (F·μ·S·B / A) be a constant X and (F·μ·S·C / A) be a constant Y. In this case, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is φ = X + Y·sin(N·θ) It satisfies the condition. As a result, the magnetic sensor 110, which detects the magnetic flux φ passing between the magnetic detection surface 111 and the teeth 121, detects a magnetic flux φ having a component proportional to sin(N·θ). Therefore, the magnetic sensor 110 can output a detection signal with a low-distortion waveform of sin(N·θ) shape corresponding to the magnetic flux φ.

[0032] [Effects of Embodiment 2] The magnetic encoder device 100 of Embodiment 2 can achieve the following effects. In the magnetic encoder device 100 of Embodiment 2, when detecting the rotational movement of a movable part 120 in which a plurality of teeth 121 are arranged at equal intervals on the outer circumference of a circle, if A, B, and C are constants satisfying B>C>0, then the distance L(θ) between the magnetic detection surface 111 and the teeth 121 that changes according to the electrical angle θ is... L(θ) = A / (B + C·sin(N·θ)) Multiple teeth 121 are configured in a shape that satisfies the following conditions. As a result, in the magnetic sensor 110, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 is φ = X + Y·sin(θ) This satisfies the condition. As a result, the magnetic sensor 110 detects a magnetic flux having a component proportional to sin(θ). Therefore, the magnetic sensor 110 can output a detection signal with a waveform that has little distortion based on the magnetic flux φ which contains a component proportional to sin(θ).

[0033] In the magnetic encoder device 100 of Embodiment 2, the movable part 120 has a plurality of teeth 121 arranged at equal intervals and is configured as a gear that can move in the rotational direction, i.e., a rotatable gear. As a result, in the magnetic encoder device 100, the magnetic flux φ passing between the magnetic sensing surface 111 and the teeth 121 of the gear is φ = X + Y·sin(N·θ) This satisfies the requirements. Therefore, in accordance with the rotational movement of the moving part 120 as a gear, the magnetic sensor 110 can output a detection signal with a waveform that has little distortion, based on the magnetic flux φ which contains a component proportional to sin(N·θ).

[0034] In the magnetic encoder device 100 of Embodiment 2, the magnetic sensor 110 can detect the magnetic flux φ = X + Y·sin(N·θ) and output a detection signal with a sinusoidal waveform and low distortion based on the magnetic flux φ which includes a component proportional to sin(N·θ). [Explanation of Symbols]

[0035] 100 Magnetic encoder device, 110 Magnetic sensor, 111 Magnetic sensing surface, 112 Magnetic sensor body, 120 Moving part, 121 Multiple teeth, 122 Base part, 123 Rotation axis, A, B, C Constants, F Magnetomotive force of the magnetic sensor, L Distance that changes according to the electrical angle θ, M Distance from the rotation center of the moving part to the magnetic sensing surface, N Number of multiple teeth, O Rotation center, Rm Magnetoresistance, r Radius that changes according to the electrical angle between the rotation center and the teeth, S Area of ​​the sensing surface, μ Permeability, φ Magnetic flux passing between the magnetic sensing surface and the teeth, θ Electrical angle, X, Y Constants.

Claims

1. A magnetic encoder device (100) comprising a magnetic sensor (110) having a magnetic sensing surface (111) and a movable part (120) having a plurality of teeth (121) made of a magnetic material, wherein the movement of the movable part (120) is detected, The moving part (120) has the multiple teeth (121) arranged in a straight line at equal intervals. When the electrical angle of the irregularities of the teeth (121) is θ, the distance between the magnetic sensing surface (111) and the teeth (121) that changes according to the electrical angle θ is L(θ), the magnetoresistance between the magnetic sensing surface (111) and the teeth (121) is Rm, the permeability of the teeth (121) is μ, the area of ​​the magnetic sensing surface (111) is S, the magnetomotive force of the magnetic sensor (110) is F, and the magnetic flux passing between the magnetic sensing surface (111) and the teeth (121) is φ, The aforementioned magnetic resistance Rm is, Rm=L(θ) / (μ・S) And, The constants A, B, and C satisfy B > C > 0. The aforementioned multiple teeth (121) are L(θ)=A / (B+C・sin(θ)) It is configured in a shape that satisfies the following conditions: The aforementioned magnetic flux φ is, φ = F / Rm =(F・μ・S) / L(θ) =(F・μ・S・(B+C・sin(θ))) / A And, If (F・μ・S・B / A) is a constant X and (F・μ・S・C / A) is a constant Y, φ=X+Y・sin(θ) Satisfying, Magnetic encoder device.

2. The moving part (120) is a rack gear having the plurality of teeth (121) and movable in a linear direction. The magnetic encoder device according to claim 1.

3. A magnetic encoder device (100) comprising a magnetic sensor (110) having a magnetic sensing surface (111) and a movable part (120) having a plurality of teeth (121) made of a magnetic material, wherein the movement of the movable part (120) is detected, The movable part (120) has the plurality of teeth (121) arranged at equal angular intervals around the outer circumference of the ring, When the electrical angle of the irregularities of the teeth (121) is θ, the distance between the magnetic sensing surface (111) and the teeth (121) that changes according to the electrical angle θ is L(θ), the distance from the rotation center of the moving part (120) to the magnetic sensing surface (111) is M, the radius between the rotation center and the teeth (121) that changes according to the electrical angle θ is r(θ), the magnetoresistance between the magnetic sensing surface (111) and the teeth (121) is Rm, the permeability of the teeth (121) is μ, the area of ​​the magnetic sensing surface (111) is S, the magnetomotive force of the magnetic sensor (110) is F, and the magnetic flux passing between the magnetic sensing surface (111) and the teeth (121) is φ, The aforementioned magnetic resistance Rm is, Rm=L(θ) / (μ・S) And, The constants A, B, and C satisfy B > C > 0, and the number of the plurality of teeth (121) is N. L(θ)=M−r(θ) from, r(θ)=M−A / (B+C・sin(N・θ)) And, The aforementioned multiple teeth (121) are L(θ)=M-(M-A / (B+C・sin(N・θ))=A / (B+C・sin(N・θ)) It is configured in a shape that satisfies the following conditions: The aforementioned magnetic flux φ is, φ = F / Rm =(F・μ・S) / L(θ) =(F・μ・S・(B+C・sin(N・θ))) / A And, If (F・μ・S・B / A) is a constant X and (F・μ・S・C / A) is a constant Y, φ=X+Y・sin(N・θ) Satisfying, Magnetic encoder device.

4. The moving part (120) is a rotatable gear having the plurality of teeth (121). The magnetic encoder device according to claim 3.

5. The magnetic sensor (110) outputs a sinusoidal detection signal corresponding to the magnetic flux φ. A magnetic encoder device according to any one of claims 1 to 4.

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