JP2010002293A - Potentiometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly detect a rotation angle of a detection object member, even when a GMR sensor is arranged on a lateral side of the member. <P>SOLUTION: A potentiometer includes a first magnet 2 in an annular shape which rotates in accordance with the rotation of the detection object member, a second magnet 3 in an annular shape which is arranged concentrically with the first magnet 2 and is different from the first magnet 2 in radial dimension, and a GMR sensor 4 arranged at a position where a magnetic field generated between the first magnet 2 and the second magnet 3 acts. The GMR-sensor-4 side inner peripheral or outer peripheral portions of the first magnet 2 and the second magnet 3 are magnetized to different polarities, and the first magnet 2 and the second magnet 3 are arranged so as to have an angle between a surface of the first magnet 2 parallel to its radial direction and a surface of the second magnet 3 parallel to its radial direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a potentiometer, and more particularly to a potentiometer using a GMR sensor having a GMR element as a magnetic sensor.

Conventionally, two magnets are attached to a generally U-shaped yoke connected to a rotation shaft while shifting the position in the axial direction of the rotation shaft, while the detection surface is vertically arranged in the center of the inner space of the yoke. There has been proposed a rotation angle detector in which a sensor is arranged and a magnetic sensor detects a magnetic field generated between both magnets according to the rotation of a rotating shaft (see, for example, Patent Document 1). In this rotation angle detector, a magnetic sensor (GMR sensor) using a ferromagnetic magnetoresistive element (GMR element) is used.
JP 2001-317910 A

  By the way, in the potentiometer which is a kind of the rotation angle detector as described above, in order to ensure the miniaturization of parts or the free design of the parts, the side of the detection target member that rotates the GMR sensor. It is requested to be placed. However, when the GMR sensor is arranged on the side of the detection target member, it is difficult to generate a magnetic field that acts on the detection surface, and the rotation angle of the detection target member cannot be detected appropriately. There's a problem.

  The present invention has been made in view of such problems, and even when a GMR sensor is disposed on the side of a detection target member, a potentiometer capable of appropriately detecting the rotation angle is provided. The purpose is to provide.

  The potentiometer of the present invention is arranged concentrically with a first magnet having an annular shape that rotates in response to rotation of a detection target member, and the first magnet. A second magnet having an annular shape with different dimensions, and a GMR sensor disposed at a position where a magnetic field generated between the first magnet and the second magnet acts, While magnetizing the inner periphery or the outer periphery of the second magnet on the GMR sensor side with different polarities, a surface along the radial direction of the first magnet and a surface along the radial direction of the second magnet, The first and second magnets are arranged so as to have an angle between them.

  According to the potentiometer, the first and second magnets are arranged so as to have an angle between the surfaces along the radial direction of each other, and the GMR is located at a position where a magnetic field generated therebetween acts. Since the sensor is arranged, the direction of the magnetic field generated between the first magnet and the second magnet can be changed according to the rotation of the detection target member. Even when the GMR sensor is arranged on the side of the detection target member, the rotation angle can be appropriately detected.

  In the potentiometer, the first and second magnets are arranged so that the surfaces along the radial direction extend in different regions with a surface orthogonal to the detection surface of the GMR sensor as a boundary surface, The second magnet is preferably rotated according to the rotation of the first magnet. In this case, since the surfaces along the radial direction are extended to different areas separated by the boundary surface orthogonal to the detection surface of the GMR sensor, the surface is generated between the first magnet and the second magnet. Since the change in the direction of the magnetic field to be applied can be increased, the occurrence rate of erroneous detection can be reduced compared to the case where this is small, and the rotation angle of the detection target member can be detected more accurately.

  In the potentiometer, one of the surfaces along the radial direction of the first or second magnet may be orthogonal to the detection surface of the GMR sensor. In this case, since one of the surfaces along the radial direction of the first or second magnet may be orthogonal to the detection surface of the GMR sensor, the surface along the radial direction of the first or second magnet is The positional relationship with the detection surface of the GMR sensor can be easily set as compared with the case where the angle is with respect to the detection surface of the GMR sensor.

  According to the present invention, the first and second magnets are disposed so as to have an angle between the surfaces along the radial direction, and the GMR sensor is disposed at a position where a magnetic field generated between these magnets acts. Since it is arranged, the direction of the magnetic field generated between the first magnet and the second magnet can be changed according to the rotation of the detection target member, so that detection is performed through detection of the change in the direction of the magnetic field. Even when the GMR sensor is arranged on the side of the target member, the rotation angle can be appropriately detected.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG.1 and FIG.2 is a schematic diagram for demonstrating the structure of the principal part of the potentiometer 1 which concerns on one embodiment of this invention. 1, the potentiometer 1 according to the present embodiment is shown from above, and in FIG. 2, the potentiometer 1 shown in FIG. 1 is shown from the left side.

  As shown in FIG. 1, a potentiometer 1 according to the present embodiment is arranged in a concentric manner with a first magnet 2 having an annular shape and a concentric shape with the first magnet 2, and is more radial than the first magnet 2. And a second magnet 3 having a large dimension. In each of the first magnet 2 and the second magnet 3, the outer peripheral portion is magnetized to the N pole, while the inner peripheral portion is magnetized to the S pole. Therefore, a magnetic field from the first magnet 2 toward the second magnet 3 is generated between the first magnet 2 and the second magnet 3. Note that the polarities of the first magnet 2 and the second magnet 3 may be reversed.

  Moreover, the 1st magnet 2 and the 2nd magnet 3 are arrange | positioned in the state to which the angle was provided between the surfaces (2A, 3A) along a mutual radial direction, as shown in FIG. Specifically, the first magnet 2 and the second magnet 3 are surfaces that are orthogonal to the detection surface of the GMR sensor 4 to be described later, and that extend along different radial directions in different regions with a surface passing through the center point as a boundary surface V. (2A, 3A) are arranged to extend.

  In the present embodiment, the surface 2A along the radial direction of the first magnet 2 at the left side portion of the GMR sensor 4 shown in FIG. The first magnet 2 and the second magnet 3 are arranged so that the surface 3A along the radial direction of the two magnets 3 extends to a region below the boundary surface V. Therefore, the magnetic field from the first magnet 2 to the second magnet 3 is generated obliquely downward as shown in FIG.

  On the other hand, in the portion on the right side of the GMR sensor 4 shown in FIG. 2, the surface 2A along the radial direction of the first magnet 2 extends to a region below the boundary surface V, while the second magnet 3 The first magnet 2 and the second magnet 3 are arranged so that the surface 3A along the radial direction of the surface extends to a region above the boundary surface V. Therefore, the magnetic field from the first magnet 2 to the second magnet 3 is generated obliquely upward as shown in FIG.

  Further, in the potentiometer 1 according to the present embodiment, a GMR (Giant magnetoresistance) sensor 4 is disposed at a position where the magnetic field generated between the first magnet 2 and the second magnet 3 acts as described above. ing. As shown in FIGS. 1 and 2, the GMR sensor 4 is fixed to the surface of the substrate 5 extending in the vertical direction at a position between the first magnet 2 and the second magnet 3. In this case, the GMR sensor 4 is arranged along the direction of the magnetic field generated from the first magnet 2 toward the second magnet 3.

  Here, an outline of the GMR sensor 4 included in the potentiometer 1 according to the present embodiment will be described. The GMR sensor 4 includes a GMR element (giant magnetoresistive element) using a giant magnetoresistive effect. This GMR element is basically formed by laminating an exchange bias layer (anti-ferromagnetic layer), a fixed layer (pinned magnetic layer), a nonmagnetic layer and a free layer (free magnetic layer) on the substrate 5 as a basic configuration. Is done. In the fixed layer (pinned magnetic layer), the direction of magnetization is fixed by exchange coupling with the exchange bias layer (antiferromagnetic layer), while in the free layer (free magnetic layer), depending on the state of the external magnetic field Thus, the direction of magnetization changes.

  In the potentiometer 1 according to the present embodiment, a magnetic field generated from the first magnet 2 toward the second magnet 3 is applied to such a GMR element. Then, the electric resistance value of the GMR element is changed by changing the magnetization direction of the free layer (free magnetic layer) according to the direction of the magnetic field, and an electric signal corresponding to the change of the electric resistance value is sent to the GMR sensor 4. Output from. This electric signal is input to the control unit of the apparatus on which the potentiometer 1 is mounted, and the control unit calculates the rotation angles of the first magnet 2 and the second magnet 3 based on the electric signal.

In order for the GMR element included in the GMR sensor 4 to exhibit the giant magnetoresistive effect (GMR), for example, the exchange bias layer is an α-Fe ₂ O ₃ layer, the fixed layer is a NiFe layer, and the nonmagnetic layer is a Cu layer. The free layer is preferably formed of a NiFe layer, but is not limited to these, and may be formed in any manner as long as it exhibits a magnetoresistive effect. Further, the GMR element is not limited to the laminated structure as described above as long as it exhibits a magnetoresistive effect.

  In the potentiometer 1 having such a configuration, the first magnet 2 is integrally attached to a detection target member (not shown) that is rotatably provided, and is configured to rotate in accordance with the rotation of the detection target member. Has been. For example, the 1st magnet 2 is penetrated by the shaft member as a detection object member, and is fixed to the outer periphery. The second magnet 3 is connected to the first magnet 2 via a connecting member (not shown), and is configured to rotate according to the rotation of the first magnet 2. That is, the first magnet 2 and the second magnet 3 are configured to be rotatable with the rotation of the detection target member.

  Here, in the potentiometer 1 which concerns on this Embodiment, the relationship between the 1st magnet 2 and the 2nd magnet 3 which rotate with rotation of a detection object member, and the magnetic field which generate | occur | produces between these is demonstrated. FIG. 3 is a schematic view when the first magnet 2 and the second magnet 3 are rotated 90 degrees in the clockwise direction from the state shown in FIG. FIG. 4 is a schematic view when the first magnet 2 and the second magnet 3 are rotated 270 degrees in the clockwise direction from the state shown in FIG. 3 and 4, the potentiometer 1 shown in FIG. 1 is shown from the upper side. For convenience of explanation, FIGS. 3 and 4 show the boundary surface V as in FIG.

  When the first magnet 2 and the second magnet 3 rotate 90 degrees in the clockwise direction from the state shown in FIG. 1, the GMR sensor 4 is arranged on the lower side of the boundary surface V as shown in FIG. 3. The magnet 2 is disposed between the outer peripheral portion of the magnet 2 and the outer peripheral portion of the second magnet 3 disposed above the boundary surface V. In this case, a magnetic field is generated between the first magnet 2 and the second magnet 3 obliquely upward. In the GMR sensor 4, as shown in FIG. 3, in response to this magnetic field, the magnetization direction of the free layer (free magnetic layer) is directed obliquely upward, and its electrical resistance value changes (here, , Shall rise).

  On the other hand, when the first magnet 2 and the second magnet 3 are rotated 270 degrees in the clockwise direction from the state shown in FIG. 1, the GMR sensor 4 is disposed above the boundary surface V as shown in FIG. It arrange | positions between the outer peripheral part of the 1st magnet 2, and the outer peripheral part of the 2nd magnet 3 arrange | positioned below the boundary surface V. FIG. In this case, a magnetic field is generated between the first magnet 2 and the second magnet 3 obliquely downward. In the GMR sensor 4, as shown in FIG. 4, in response to this magnetic field, the magnetization direction of the free layer (free magnetic layer) is directed obliquely downward, and its electrical resistance value changes (here, , Shall descend).

  In addition, when the relationship between the 1st magnet 2 and the 2nd magnet 3, and the GMR sensor 4 exists in the state shown in FIG. 1, and the 1st magnet 2 and the 2nd magnet 3 are clockwise from the state shown in FIG. When rotated 180 degrees, the GMR sensor 4 is disposed between the outer peripheral portions of the first magnet 2 and the second magnet 3 disposed at the same height as the boundary surface V. In this case, a magnetic field is generated horizontally between the first magnet 2 and the second magnet 3 toward the outside. In the GMR sensor 4, in response to this magnetic field, the magnetization direction of the free layer (free magnetic layer) is in a state of being horizontally directed outward.

  In this case, the rotation angle of the first magnet 2 and the second magnet 3 (hereinafter referred to as “magnet rotation angle”) and the angle of the magnetic field detected between them (hereinafter referred to as “magnetic field angle”) are: The relationship shown in FIG. 5 is obtained. In FIG. 5, the case where the relationship between the first magnet 2 and the second magnet 3 and the GMR sensor 4 is in the state shown in FIG.

  As shown in FIG. 5, the magnetic field angle shows the highest value when the magnet rotation angle is 90 °, and shows the lowest value when the magnet rotation angle is 270 °. No rotation angle is shown when the magnet rotation angles are 180 ° and 360 °. In the GMR sensor 4, since the electric resistance value of the GMR element changes according to the direction of the magnetic field changing in this way, the magnetic field angle can be detected by the control unit based on the output signal. And by grasping | ascertaining the relationship shown in FIG. 5 beforehand, since a magnet rotation angle can be detected according to the magnetic field angle, it becomes possible to detect the rotation angle of a detection target member according to this.

  As described above, in the potentiometer 1 according to the present embodiment, the first magnet 2 has an angle between the surface along the radial direction of the first magnet 2 and the surface along the radial direction of the second magnet 3. Since the 1 magnet 2 and the second magnet 3 are arranged, and the GMR sensor 4 is arranged at a position where a magnetic field generated between them is applied, the first magnet 2 and the second magnet are rotated according to the rotation of the detection target member. 3, the direction of the magnetic field generated between the GMR sensor 4 and the GMR sensor 4 can be appropriately rotated even when the GMR sensor 4 is disposed on the side of the detection target member through detection of the change in the direction of the magnetic field. An angle can be detected.

  In particular, in the potentiometer 1 according to the present embodiment, the first magnet is formed so that the surfaces along the radial direction extend to different regions with the surface orthogonal to the detection surface of the GMR sensor 4 as a boundary surface V. 2 and the second magnet 3 are arranged, and the second magnet 3 is rotated according to the rotation of the first magnet 2. Thereby, since the change in the direction of the magnetic field generated between the first magnet 2 and the second magnet 3 can be increased, the occurrence rate of false detection can be reduced as compared with the case where this is small, and the detection can be performed more accurately. It becomes possible to detect the rotation angle of the target member.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the said embodiment, the case where the surface (2A, 3A) along the mutual radial direction in the 1st magnet 2 and the 2nd magnet 3 extends to a different area | region using the boundary surface V mentioned above as a boundary is demonstrated. is doing. However, the positional relationship between the first magnet 2 and the second magnet 3 is not limited to this, and can be changed as appropriate. For example, one of the surfaces along the radial direction of the first magnet 2 and the second magnet 3 may be horizontal with the above-described boundary surface V, and the other may be in a state in which an angle is given between the boundary surface V and the other. .

  Even when the positional relationship between the first magnet 2 and the second magnet 3 is changed in this way, the change rate of the magnetic field angle is narrowed, but the magnet rotation angle can be detected, and the rotation angle of the detection target member can be detected. It becomes. In this case, as compared to the case where the surfaces along the radial direction of the first magnet 2 and the second magnet 3 have an angle with respect to the detection surface of the GMR sensor 4 as in the above embodiment. The positional relationship with the detection surface of the GMR sensor 4 can be easily set. In addition, when one of the surfaces along the radial direction of the first magnet 2 and the second magnet 3 is made horizontal with the boundary surface V described above, the magnet not connected to the detection target member is not necessarily the detection target. It is not necessary to rotate according to the rotation of the member.

  Moreover, in the said embodiment, although shown about the case where the 1st magnet 2 arrange | positioned inside is attached to a detection target member integrally, about the structure attached to a detection target member, it is 2nd magnet 3. There may be. Even in this case, similarly to the above-described embodiment, it is possible to detect the rotation angle of the detection target member through the detection of the magnet rotation angle.

It is a schematic diagram for demonstrating the structure of the principal part of the potentiometer which concerns on one embodiment of this invention. It is a schematic diagram for demonstrating the structure of the principal part of the potentiometer which concerns on the said embodiment. It is a schematic diagram when the 1st magnet and the 2nd magnet rotate 90 degrees in the clockwise direction from the state shown in FIG. It is a schematic diagram when the 1st magnet and the 2nd magnet rotate 270 degrees in the clockwise direction from the state shown in FIG. It is a figure which shows the rotation angle of the 1st magnet in the potentiometer which concerns on the said embodiment, and the 2nd magnet, and the angle of the magnetic field detected among these.

Explanation of symbols

1 Potentiometer 2 First magnet 3 Second magnet 4 GMR sensor 5 Substrate

Claims (3)

A first magnet having an annular shape that rotates according to the rotation of the detection target member, and an annular shape that is arranged concentrically with the first magnet and has a radial dimension different from that of the first magnet. A second magnet, and a GMR sensor disposed at a position where a magnetic field generated between the first magnet and the second magnet acts,
The inner and outer peripheral portions of the first and second magnets on the GMR sensor side are magnetized to have different polarities, and the surface along the radial direction of the first magnet and the radial direction of the second magnet A potentiometer, characterized in that the first and second magnets are arranged so as to have an angle with a surface along the surface.   The first and second magnets are arranged so that the surfaces along the radial direction extend to different regions with a surface orthogonal to the detection surface of the GMR sensor as a boundary surface, and the second magnet is The potentiometer according to claim 1, wherein the potentiometer is rotated according to the rotation of the first magnet.   2. A potentiometer according to claim 1, wherein one of the surfaces of the first or second magnet along the radial direction is orthogonal to the detection surface of the GMR sensor.

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