JP2010009170A - Plane pointing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a mechanism for plane position detection to thin a plane pointing device. <P>SOLUTION: In this plane pointing device, a flat magnet 1 of a flat circular ring shape is flat-movably disposed inside a movable range M formed on a substrate, and first and second GMR sensors 2, 3 are disposed inside the same plane as the flat magnet 1 on the outer circumference of the movable range M. A direction of a magnetic field acting on the first and second GMR sensors 2, 3 changes according to a movement position of the flat magnet 1, and the movement position is detected from a direction of magnetization of a free layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a planar pointing device that detects a two-dimensional coordinate position of a magnet that moves on a two-dimensional plane.

  Conventionally, a contact-type pointing device using a variable resistance element as a planar pointing device for detecting a two-dimensional coordinate on a two-dimensional plane, and a non-contact type pointing device using a magnetic sensor are known. In the contact type pointing device, variable resistors whose resistance values change according to the contact position with the movable contact are arranged along the X-axis direction and the Y-axis direction orthogonal to each other, and the movable part on the two-dimensional plane is arranged. In accordance with the movement, the movable contact is slid on the variable resistor in the X and Y axis directions, and the resistance value of the variable resistor is read to detect a two-dimensional coordinate. However, since the contact type pointing device is slid by contacting the variable resistor and the movable contact, the structure is complicated and it is difficult to reduce the size.

  On the other hand, a non-contact type pointing device holds a magnet so as to be movable on a two-dimensional plane, detects a magnetic field change according to the two-dimensional coordinate position of the magnet in a non-contact manner, and obtains a two-dimensional coordinate. (For example, refer to Patent Document 1). For this reason, there is an advantage that it becomes unnecessary to provide a sliding mechanism such as a contact type pointing device.

  A non-contact type planar pointing device described in Patent Document 1 will be described with reference to FIGS. 5 and 6. A resin portion 12 including a fixing portion 12a and a holding portion 12b is disposed on the main surface 11a of the mounting substrate 11. A flat magnet 13 having a disc shape is held by a central recess of the holding portion 12b having a substantially cylindrical shape. A magnetic sensor 20 having a main body 20a and a salient electrode 20b is provided on the lower surface 11b of the mounting substrate 11. The main body 20a is disposed at a position facing the flat magnet 13 at the initial position. As shown in FIG. 6, the main body 20a includes first to fourth GMR elements R1 to R4 on the main surface of the sensor substrate, and the first GMR element R1 is an end in the Y-axis positive direction on the main surface of the sensor substrate. The second GMR element R2 is disposed at the Y-axis negative direction end, the third GMR element R3 is disposed at the X-axis negative direction end on the main surface of the sensor substrate, and the fourth GMR element R4 is disposed at the end in the positive direction of the X axis.

In such a planar pointing device, as shown in FIGS. 6A to 6E, the first to fourth GMR elements R1 according to the X and Y coordinate positions on the XY plane (main surface 11a) of the flat magnet 13 are used. The magnetization direction of the free layer of ~ R4 changes. The resistance value (output) of the GMR element changes according to the magnetization direction of the free layer. Therefore, the output signals of the first to fourth GMR elements R1 to R4 are taken into a magnet position determining unit (not shown) provided in the magnetic sensor 20 and converted into X and Y coordinate positions.
JP 2006-276983 A

  Recently, there has been a demand for thinning of a device body such as a mobile phone, and there is a demand for further thinning of a device mounted on the device body of a mobile phone such as a flat pointing device. However, the above-described planar pointing device described in Patent Document 1 has a limit in achieving further thinning because of the structure in which the flat magnet 13 and the magnetic sensor 20 are opposed to each other with the mounting substrate 11 interposed therebetween. .

  The present invention has been made in view of the above points, and an object of the present invention is to provide a planar pointing device that can simplify a mechanism for detecting a planar position and can easily realize a reduction in thickness.

  The planar pointing device of the present invention is a planar pointing device for detecting a position within a moving range of a magnet arranged so as to be capable of plane movement in an XY plane defined by an X axis and a Y axis orthogonal to each other. The magnet is magnetized so that the magnetic field lines generated from the magnet are emitted from the magnet toward the outer periphery of the moving range or in the opposite direction, and the magnetic field of the magnet acts in the same plane as the magnet. GMR sensors are arranged at a plurality of locations on the outer periphery of the moving range, and the position of the magnet is detected from the output signal of each GMR sensor.

  According to this configuration, since the GMR sensors are arranged at a plurality of locations on the outer periphery of the moving range in which the magnetic field of the magnet acts within the same plane as the magnet, the magnet and the GMR sensor are arranged above and below the substrate. Compared with, it is possible to significantly reduce the thickness.

  In the planar pointing device, it is preferable to use a plate-shaped magnet as the magnet. As the magnet having a flat plate shape, a magnet having a flat disk shape or a flat plate ring shape can be used.

  According to the present invention, in the planar pointing device, the GMR sensors are respectively installed on two line segments that pass through a central portion of the moving range of the magnet and are orthogonal to each other.

  With this configuration, the GMR sensor is installed on two line segments that are orthogonal to each other through the center of the moving range of the magnet, so that the direction of the magnetic field acting on the GMR sensor when the magnet moves in all directions The change becomes larger on average, and the position detection accuracy based on the change in the direction of the magnetic field can be improved.

  Further, according to the present invention, in the planar pointing device, an auxiliary magnet that draws a magnetic field radiated from the magnet toward the outer periphery of the moving range to the GMR sensor side is provided behind the GMR sensor as viewed from the magnet side. It is characterized by having arranged.

  With this configuration, since the auxiliary magnet for drawing the magnetic field radiated from the magnet to the GMR sensor side is provided, a sufficiently large magnetic field can be applied to the GMR sensor from the magnet even if the distance between the magnet and the GMR sensor is long. It is possible to prevent a decrease in detection accuracy.

  According to the present invention, it is possible to simplify the mechanism for detecting the planar position of the planar pointing device, and to realize a reduction in thickness.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic plan view of a planar pointing device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA shown in FIG. A flat plate magnet 1 having a circular plate shape is arranged so as to be slidable in an arbitrary direction in accordance with an external force within a movable range M which is a magnet moving range on the XY plane. The first GMR sensor 2 is provided at the end of the movable range M in the X-axis direction, and the second GMR sensor 3 is provided at the end of the movable range M in the Y-axis direction. In the present embodiment, the movable range M is a square, the first GMR sensor 2 is fixed at an intermediate position on one side in the Y-axis direction, and the second GMR sensor 3 is fixed at an intermediate position on one side in the X-axis direction. Yes. Therefore, the line segment passing from the first GMR sensor 2 through the center point P of the movable range M and the line segment passing from the second GMR sensor 3 through the center point P of the movable range M are orthogonal to each other. .

  As shown in FIG. 2, the flat magnet 1 and the first and second GMR sensors 2 and 3 are arranged on the same plane as the upper surface 4 a of the substrate 4. In FIG. 2, the second GMR sensor 3 cannot be seen due to the viewpoint. On the upper surface 4 a of the substrate 4, a side wall portion 5 that defines the outer peripheral portion of the movable range M is formed, and the flat magnet 1 is disposed in a recess formed by the upper surface 4 a and the side wall portion 5. The flat plate magnet 1 is fixed to a holding portion (not shown), and the holding portion and the flat plate magnet 1 are integrated so as to move in the movable range M in an arbitrary direction.

  In addition, the structure of the holding | maintenance part which fixes the flat magnet 1 may be the same as that of the resin part 12 shown, for example in FIG. Or the structure which slides the flat magnet 1 or its holding | maintenance part on the upper surface 4a may be sufficient. In the case of a slide structure, the outer diameter of the flat magnet 1 is sufficiently smaller than one side piece of the movable range M, and is set according to the moving distance of the flat magnet 1 within the movable range M.

  The flat magnet 1 has a flat annular shape as a whole, the magnet outer peripheral portion 1a is magnetized to the N pole, and the magnet inner peripheral portion 1b is magnetized to the S pole. Therefore, as shown in FIG. 3, the lines of magnetic force radiated from the outer peripheral portion 1a (N pole) of the flat magnet 1 to the outer peripheral portion (left direction in FIG. 3) of the movable range M along the flat plate plane form an arc. It inputs into the inner peripheral part 1b (S pole) of the magnet 1. Since the flat magnet 1 has a flat annular shape as a whole, uniform magnetic field lines are radiated radially from the outer peripheral portion 1a (N pole) along the flat plate plane. Since the first and second GMR sensors 2 and 3 are arranged in the same plane as the flat magnet 1, the lines of magnetic force radiated outward from the outer peripheral portion 1 a (N pole) of the flat magnet 1 are the first and second. The GMR sensors 2 and 3 are penetrated. The main lines of magnetic force incident on the first and second GMR sensors 2 and 3 are lines of magnetic force radiated toward the first and second GMR sensors 2 and 3 when viewed from the center of the flat magnet 1.

  Here, an outline of the first and second GMR sensors 2 and 3 included in the planar pointing device according to the present embodiment will be described. Each of the GMR sensors 2 and 3 includes a GMR element (giant magnetoresistive element) using a giant magnetoresistive effect. This GMR element is basically formed by laminating an exchange bias layer (antiferromagnetic layer), a fixed layer (pinned magnetic layer), a nonmagnetic layer and a free layer (free magnetic layer) on a substrate. The 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 flat pointing device according to the present embodiment, a magnetic field generated radially from the flat magnet 1 toward the same substrate surface as the substrate 4 on which the flat magnet 1 is disposed is applied to such a GMR element. Then, the electric resistance value of the GMR element is changed by changing the direction of the magnetic field lines forming the magnetic field to change the direction of magnetization of the free layer (free magnetic layer). Electric signals corresponding to changes in the electric resistance value of the GMR element are output from the GMR sensors 2 and 3. This electrical signal is input to the control unit of the apparatus on which the planar pointing device is mounted, and the control unit calculates the XY coordinate position within the movable range M of the flat magnet 1 based on the electrical signal. For example, a lookup table is prepared in which the XY coordinate position within the movable range M and the output signal pattern from the GMR sensors 2 and 3 corresponding to each XY coordinate are associated with the control unit. By using the look-up table, the corresponding XY coordinate position can be instantaneously extracted from the GMR sensors 2 and 3 with the output signal pattern as an input.

In order for the GMR elements included in the first and second GMR sensors 2 and 3 to exhibit the giant magnetoresistance effect (GMR), for example, the exchange bias layer is an α-Fe ₂ O ₃ layer, and the fixed layer is NiFe. The layer and the nonmagnetic layer are preferably formed of a Cu layer, and the free layer is formed of a NiFe layer. However, the present invention is not limited to these, and any method can be used as long as it exhibits a magnetoresistive effect. It may be. Further, the GMR element is not limited to the laminated structure as described above as long as it exhibits a magnetoresistive effect.

  4A to 4F show the relationship between each moving position of the plate magnet 1 within the movable range M and the magnetic field (lines of magnetic force) acting on the first and second GMR sensors 2 and 3 from the plate magnet 1. FIG. FIG. 4A shows a state in which the center position of the flat magnet 1 is disposed at a place P1 (x0, y0) where the center position P of the movable range M coincides with the center position P. FIG. 4 (d) shows the direction of the magnetic field (lines of magnetic force) acting on the first and second GMR sensors 2 and 3 at the movement position of FIG. 4 (a). As shown in the figure, the direction of the magnetic field (lines of magnetic force) acting on the first GMR sensor 2 is mainly magnetic lines of force parallel to the X axis. On the other hand, the magnetic field acting on the second GMR sensor 3 is a magnetic force line that is mainly parallel to the Y axis. Accordingly, in the first GMR sensor 2, the magnetization direction of the free layer is parallel to the X axis. In the second GMR sensor 3, the magnetization direction of the free layer is parallel to the Y axis.

  FIG. 4B shows a state in which the flat magnet 1 has moved from the center position P of the movable range M to a place P2 (x1, y0) that is a predetermined distance away in the right direction in the figure. FIG. 4 (e) shows the direction of the magnetic field (lines of magnetic force) acting on the first and second GMR sensors 2 and 3 at the magnet position in FIG. 4 (b). As shown in the figure, the magnetic field acting on the first GMR sensor 2 is a magnetic force line parallel to the X axis. On the other hand, the magnetic field acting on the second GMR sensor 3 is a magnetic field line oriented in a direction rotated mainly by the angle θ1 clockwise from the Y axis. Accordingly, in the first GMR sensor 2, the magnetization direction of the free layer is parallel to the X axis. In the second GMR sensor 3, the magnetization direction of the free layer is rotated clockwise from the Y axis by an angle θ1.

  FIG. 4 (c) shows a state in which the flat magnet 1 has moved from the center position P of the movable range M to the place P3 (x1, y1) that is a predetermined distance away from the center position P in the right direction and a predetermined distance in the Y axis direction. ing. FIG. 4 (f) shows the direction of the magnetic field (lines of magnetic force) acting on the first and second GMR sensors 2 and 3 at the magnet position in FIG. 4 (c). As shown in the figure, the magnetic field acting on the first GMR sensor 2 is a magnetic field line oriented in a direction rotated mainly by an angle θ2 counterclockwise from the X axis. On the other hand, the magnetic field acting on the second GMR sensor 3 is a magnetic field line oriented in the direction rotated mainly by the angle θ3 clockwise from the Y axis. Therefore, in the first GMR sensor 2, the magnetization direction of the free layer is the direction rotated counterclockwise from the X axis by the angle θ2. In the second GMR sensor 3, the magnetization direction of the free layer is the direction rotated clockwise by θ3 from the Y axis.

  As described above, the direction of magnetization of the free layers of the first and second GMR sensors 2 and 3 is moved by moving the plate magnet 1 having a circular plate shape in an arbitrary direction within the movable range M. It changes in the direction according to the position. When the magnetization directions of the free layers of the first and second GMR sensors 2 and 3 change corresponding to the movement position of the flat magnet 1, the electrical resistance value of the GMR element in each GMR sensor 2 and 3 changes. An electric signal corresponding to the change in the electric resistance value is taken into the control unit from the GMR sensors 2 and 3, and the XY coordinate position within the movable range M of the flat magnet 1 is calculated.

  Thus, according to the present embodiment, the first and second GMR sensors 2 are arranged along the outer periphery of the movable range M in the same plane as the flat plate-shaped magnet 1 arranged in the movable range M. , 3 can be detected in a non-contact manner, and the thickness of the flat magnet 1 can be significantly reduced as compared with the case where the GMR sensor is disposed on the lower surface side of the substrate 4.

  In addition, like the planar pointing device of the present embodiment, the first GMR sensor 2 and the second GMR sensor 3 are arranged on lines orthogonal to each other that pass through the center point P of the movable range M. Even if the magnet 1 can move in any direction from the center point P, the direction of the magnetic field acting on the first and second GMR sensors 2 and 3 can be greatly changed on average, and the detection accuracy can be improved. Can be achieved.

  However, in the present invention, the first and second GMR sensors 2 and 3 do not necessarily need to be arranged on mutually orthogonal lines passing through the center point P of the movable range M. If the first and second GMR sensors 2 and 3 are installed at positions spaced apart from each other on the outer periphery of the movable range M, the amount of change in the magnetization direction of the free layer is smaller depending on the moving direction than when they are arranged orthogonally. However, since the direction of magnetization of the free layer changes, it is possible to detect the moving position of the magnet.

  In addition, the flat plate magnet 1 having an annular shape is suitable for generating a radially uniform magnetic field toward the outer peripheral portion of the movable range M. If the direction of the magnetic field acting on the GMR sensors 2 and 3 changes, it does not necessarily have to be an annular shape. For example, it may be a disk shape or other flat plate shape.

  Moreover, when the magnetic field which acts on the 1st and 2nd GMR sensors 2 and 3 from the flat magnet 1 is weak, there exists a possibility that the direction of magnetization of the free layer of a GMR sensor may not fully change. Therefore, as indicated by a two-dot chain line in FIG. 1, auxiliary magnets 6 and 7 are installed in proximity to the back of the first and second GMR sensors 2 and 3. When the auxiliary magnets 6 and 7 are operated so as to draw the magnetic field radiated from the flat magnet 1 toward the first and second GMR sensors 2 and 3, and sufficient accuracy cannot be realized with the magnetic field of the flat magnet 1 alone. Even so, by combining the auxiliary magnets 6 and 7, the magnetic field acting on the first and second GMR sensors 2 and 3 from the flat magnet 1 can be increased, and the detection accuracy can be improved.

  In the above embodiment, the outer peripheral portion of the flat magnet 1 is magnetized to the N pole and the inner peripheral portion is magnetized to the S pole. Conversely, the outer peripheral portion is magnetized to the S pole, The circumference may be magnetized to the N pole. In addition to the first and second GMR sensors 2 and 3, an additional GMR sensor may be provided on the outer periphery of the movable range M.

  The present invention can be applied to a planar pointing device that detects a pointing position on a two-dimensional plane in a mobile phone or the like.

1 is a schematic plan view of a planar pointing device according to an embodiment of the present invention. AA sectional view taken along line AA shown in FIG. The schematic diagram which shows the relationship between the magnetic field which generate | occur | produces from a magnet in the said one Embodiment, and a GMR sensor. The figure which shows the relationship between each moving position of a magnet, and the magnetic field (line of magnetic force) which acts on the 1st and 2nd GMR sensor from the said magnet. The figure which shows the cross-section of the conventional non-contact type pointing device The figure which shows the correspondence of the positional relationship of a magnet and a magnetic sensor, and the magnetization direction of the free layer of a GMR element

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flat magnet, 1a ... Outer peripheral part (N pole), 1b ... Inner peripheral part (S pole), 2 ... First GMR sensor, 3 ... Second GMR sensor, 4 ... Substrate, 4a ... Upper surface of substrate 5 ... Side wall

Claims (5)

A plane pointing device for detecting a position within a moving range of a magnet arranged so as to be movable in an XY plane defined by an X axis and a Y axis orthogonal to each other,
Magnetizing the magnet so that the magnetic field lines generated from the magnet are radiated from the magnet toward the outer periphery of the moving range or in the opposite direction,
A plane in which GMR sensors are arranged at a plurality of locations on the outer periphery of a moving range in which the magnetic field of the magnet acts, and the position of the magnet is detected from the output signal of each GMR sensor. pointing device.   The flat pointing device according to claim 1, wherein the magnet has a flat plate shape.   3. The flat pointing device according to claim 1, wherein the magnet is flat and has a disk shape or an annular shape.   4. The planar pointing device according to claim 1, wherein the GMR sensors are respectively installed on two line segments that pass through a central portion of the moving range of the magnet and are orthogonal to each other. 5. The auxiliary magnet that draws the magnetic field radiated from the magnet toward the outer periphery of the moving range to the GMR sensor side is disposed behind the GMR sensor as viewed from the magnet side. A planar pointing device according to claim 4.

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