JP2009150786A - Magnetic type coordinate position detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide magnetic type coordinate position detection capable of utilizing an inexpensive detection magnet by using a magnetic sensor composition having sensitivity in a low magnetic field, by solving the problem caused by individual characteristic dispersion, or arrangement accuracy or wiring connection on a fixing mounting substrate, or the like. <P>SOLUTION: A magnetic sensor is packaged by being equipped with a plurality of anisotropic magnetic resistance elements and a bias magnet formed on the substrate (substrate in the sensor), and a moving magnet and the bias magnet are magnetized in a direction vertical to a plane along with the moving magnet is moved, and mutually opposite surfaces are magnetized to the same pole. In the magnetic sensor, four domains are formed on positions having the same distance from the origin on the X-axis and the Y-axis by using a magnetic center on a magnetic pole surface of the bias magnet as the origin, on the substrate in parallel with the magnetic pole surface of the bias magnet, and each anisotropic magnetic resistance element extended in a direction forming an angle of 45° (or 135°) with the axis is formed respectively relative to each domain, and the magnetic sensor is constituted of the four anisotropic magnetic resistance elements in total. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetic coordinate position detection apparatus that detects the position of a moving detection body using a magnetic sensor.

  There are applications to pointing devices and linear encoders as devices that detect the position of a moving detection body and use it as information. In recent years, this apparatus has been used in mobile phones and mobile electronic devices, and miniaturization has been demanded. As such a position detection device, there are technologies disclosed in Patent Documents 1 to 3. The techniques of Patent Documents 1 and 3 are applied to a pointing device, and the technique of Patent Document 2 is applied to a camera shake correction encoder.

  FIG. 8 shows the basic structure of the position detection device in Patent Documents 1 and 2. As shown in FIGS. 8A and 8B, the four magnetic sensors 33, 34, 35, and 36 packaged one by one are set to the X axis and Y with the substrate center on the mounting substrate 32 as the origin. Arrange them at symmetrical positions on the axis. In this state, the magnet 31 magnetized in the Z-axis direction moves the XY coordinates on the top of the magnetic sensor, so that the four magnetic sensors detect changes in the magnetic flux density of the magnet 31 due to the movement. For example, the distance between the magnetic sensors 33 and 34 is set in five stages of x1 to x5 (x1> x2> x3> x4> x5, and the difference between the distances of x1 and x5 is about 1 mm), and the diameter is larger than the distance x1. When the signals of the magnetic sensors 33 and 34 when the magnet 31 having a movement in the X-axis direction is confirmed through the differential amplifier, the output is different as shown in FIG. FIG. 8C shows that the output changes according to the distance between the magnetic sensors. In other words, since the magnetic sensors used for detection are arranged on the mounting substrate, the magnetic sensors packaged one by one, if the positional accuracy when mounting the magnetic sensor is poor, the X-axis direction and the Y-axis direction A sensitivity difference occurs.

FIG. 9 shows the basic structure of the position detection device in Patent Document 3. As shown in FIGS. 9A and 9B, four magnetic sensors 39, 40, 41, and 42, which are packaged one by one, are set to the X axis and the Y axis with the substrate center on the mounting substrate 38 as the origin. Place them in the upper symmetrical positions. In the case of this patent document 3, unlike the configuration of FIG. 8, the magnet 37 moves the XY coordinates at the same height as the magnetic sensors 39 to 42. In this state, the magnet 37 magnetized in the Z-axis direction moves the XY coordinates on the upper side of the magnetic sensor, so that the four magnetic sensors detect changes in the magnetic flux density of the magnet 37 due to the movement. For example, the distance between the magnetic sensors 39 and 40 is x′1 to x′5 (x′1>x′2>x′3>x′4> x′5, and the distance between x′1 and x′5. 9), and when the magnet 37 moves in the X-axis direction, when the signals of the magnetic sensors 39 and 40 are confirmed through a differential amplifier, the output is different from the graph shown in FIG. 9C. Become. That is, since the magnetic sensors used for detection are arranged on the mounting substrate, each of the magnetic sensors packaged one by one, if the position accuracy of the device mounting the magnetic sensor is poor, the X-axis direction and the Y-axis direction The output peak-to-peak differs and a difference occurs in the detection limit range.
JP 2002-150904 A JP 2006-47054 A JP 2006-146524 A

  As described above, in the position detection devices in Patent Documents 1 to 3, it is necessary to mount four magnetic sensors, respectively. There is a problem that it occurs or a difference occurs in the detection limit range. In addition, since different magnetic sensors are used, individual characteristics are likely to vary, and there is a possibility that a desired value cannot be obtained as an output signal. Furthermore, since the four magnetic sensors have independent wiring and need to be connected on the mounting substrate, there is a problem that they are easily affected by noise and the like.

  The present invention has been made in view of the above problems, and by reducing the size of the four magnetic sensors into a single magnetic sensor without deteriorating the characteristics, individual characteristic variations can be fixed on the mounting substrate. The purpose is to provide magnetic coordinate position detection that can use inexpensive detection magnets by using a magnetic sensor composition that is sensitive to low magnetic fields. is there.

  According to a first aspect of the present invention, there is provided a magnetic coordinate system comprising: a moving magnet attached to a detection target and moving within a fixed radius on a plane; and a magnetic sensor for detecting a change in magnetic vector due to a change in position of the moving magnet. A magnetic coordinate position, wherein the magnetic sensor is packaged with a plurality of anisotropic magnetoresistive elements formed on a substrate (substrate in the sensor) and a bias magnet. It is a detection device.

  According to a second aspect of the present invention, in addition to the first aspect, the moving magnet and the bias magnet are magnetized in a direction perpendicular to the plane on which the moving magnet moves, and surfaces facing each other have the same polarity. It is a magnetic coordinate position detecting device characterized in that it is magnetized.

  According to a third aspect of the present invention, in addition to the first or second aspect, the magnetic sensor has an X-axis on a substrate parallel to the magnetic pole surface of the bias magnet, with the magnetic center of the magnetic pole surface of the bias magnet as the origin. And four regions formed at the same distance from the origin on the Y-axis, and an anisotropic magnetoresistive element extended in a direction forming an angle of 45 ° (or 135 °) with the axis with respect to each region. And a total of four anisotropic magnetoresistive elements, and a magnetic coordinate position detecting device.

  According to a fourth aspect of the present invention, in addition to the first or second aspect, the magnetic sensor has an X axis on the substrate parallel to the magnetic pole surface of the bias magnet, with the magnetic center of the magnetic pole surface of the bias magnet as the origin. And four regions are formed at the same distance from the origin on the Y-axis, and the angle formed by the extending direction of each region is perpendicular to each other and the angle of 45 ° (or 135 °) with the axis. A magnetic coordinate position detection device comprising a total of eight anisotropic magnetoresistive elements formed by adjoining two anisotropic magnetoresistive elements extending in the direction of

  According to the first aspect of the present invention, the magnetic sensor is formed by packaging together a plurality of anisotropic magnetoresistive elements formed on a substrate (substrate in the sensor) and a bias magnet. Since the sensitivity to a low magnetic field can be made higher than that of a conventional Hall element or semiconductor magnetoresistive element, the apparatus can be configured even if the moving magnet is small or an inexpensive ferrite magnet. It becomes possible. In addition, for example, by combining a plurality of anisotropic magnetoresistive elements into one magnetic sensor and reducing the size, individual characteristic variations, placement accuracy on a mounting substrate to be fixed, and problems due to wiring connection are solved. By using a magnetic sensor composition sensitive to a low magnetic field, it is possible to provide magnetic coordinate position detection in which an inexpensive detection magnet can be used.

  According to a second aspect of the present invention, the moving magnet and the bias magnet are magnetized in a direction perpendicular to the plane on which the moving magnet moves, and the opposing surfaces are magnetized to the same polarity. As a result, a combined magnetic vector of the magnetic vectors of the two magnets is generated, and this combined magnetic vector changes in synchronization with the change in the positional relationship between the moving magnet and the bias magnet. Therefore, the setting of the detection area (detection limit range) can be easily changed by simply changing the size of the moving magnet.

  According to the third aspect of the present invention, the anisotropic magnetoresistive elements extending in the direction forming an angle of 45 ° (or 135 °) with the axis are formed in the four regions on the substrate in the magnetic sensor. Since a total of four anisotropic magnetoresistive elements are formed, the four anisotropic magnetoresistive elements and the bias magnet can be packaged together to form a magnetic sensor. There is no need to worry about the positioning accuracy of the mounting, which was a problem. In addition, since four anisotropic magnetoresistive elements are used, the input resistance between Vcc and Gnd increases and the value of the flowing current decreases, resulting in a reduction in power consumption.

  According to the fourth aspect of the present invention, with respect to each of the four regions in the magnetic sensor, an angle formed between the extending directions of each of the four regions is vertical and an angle of 45 ° (or 135 °) with the axis. Two stretched anisotropic magnetoresistive elements are formed adjacent to each other so that they are composed of a total of eight anisotropic magnetoresistive elements, so a Wheatstone bridge is constructed using eight anisotropic magnetoresistive elements. This makes it more resistant to electrical noise and obtains a higher output.

  A magnetic coordinate position detection apparatus according to the present invention includes a moving magnet that is attached to a detection target and moves within a certain radius on a plane, and a magnetic sensor that detects a change in magnetic vector due to a change in position of the moving magnet. A magnetic coordinate position detection device, wherein the magnetic sensor is packaged with a plurality of anisotropic magnetoresistive elements formed on a substrate (substrate in the sensor) and a bias magnet, the moving magnet and the bias The magnet is magnetized in a direction perpendicular to the plane on which the moving magnet moves, and surfaces facing each other are magnetized to the same polarity, and the magnetic sensor is parallel to the magnetic pole surface of the bias magnet. Four regions are formed on the substrate at the same distance from the origin on the X-axis and the Y-axis with the magnetic center of the magnetic pole surface of the bias magnet as the origin, and the regions are extended with respect to each other. Direction Are formed by adjoining two anisotropic magnetoresistive elements extending in a direction perpendicular to the axis and forming an angle of 45 ° (or 135 °) with the axis. It is characterized by being configured.

Embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1A is a perspective view of a magnetic coordinate position detection apparatus 10 of the present invention. A magnetic sensor 11 serving as a detection unit is fixed on the mounting substrate 13, and the magnet 12 is moved by plane coordinates on the top of the magnetic sensor 11. In the initial state, the moving magnet 12 is positioned directly above the magnetic sensor 11.

  FIG. 1B is a side view of the magnetic coordinate position detection apparatus 10. The magnetic sensor 11 has an anisotropic magnetoresistive element (17-20, or 21a-24a, 21b-24b) formed on an in-sensor substrate 14 made of a Si substrate or a glass substrate attached to the lead frame 16, The lead frame 16 is packaged with a bias magnet 15 on the back surface. The moving magnet 12 and the bias magnet 15 are magnetized in the Z-axis direction and are installed so that the surfaces facing each other have the same polarity. As long as the poles of the moving magnet 12 and the bias magnet 15 are opposed to each other, there is no restriction on the position replacement of the bias magnet 15, the formed sensor substrate 14, and the moving magnet 12 in the Z-axis direction.

  The anisotropic magnetoresistive elements (17-20, or 21a-24a, 21b-24b) formed on the sensor inner substrate 14 in the magnetic sensor 11 are used in the prior art described with reference to FIGS. Unlike Hall elements that detect magnetic fields in the direction perpendicular to the sensor surface and semiconductor magnetoresistive elements (SMR) that use changes in charged particles due to Lorentz force, ferromagnetic metals such as Ni, Fe, and Co are used. It consists of a thin film of an alloy as a main component, and the resistance value decreases when a horizontal magnetic field is applied to the thin film forming surface. This invention is an anisotropic magnetoresistive element (Anisotropic-Magneto-Resistance) using this effect. Anisotropic magnetoresistive elements (17-20, or 21a-24a, 21b-24b) have higher sensitivity to low magnetic fields than conventional Hall elements and semiconductor magnetoresistive elements. Therefore, even if the moving magnet is small or an inexpensive ferrite magnet, the apparatus can be configured.

  In the case of a spin valve type giant magnetoresistive element (GMR) used in a conventional magnetic sensor (for example, Japanese Patent Application Laid-Open No. 2006-276983), the manufacturing process is complicated and the manufacturing cost is high. However, since the magnetic sensor is configured using the anisotropic magnetoresistive element as in the present invention, there is an advantage that the manufacturing process is simple and the manufacturing cost is low. The element is adopted.

  FIG. 2A shows a positional relationship between the bias magnet 15 and the anisotropic magnetoresistive elements 17 to 20 in the magnetic sensor 11. The sensor inner substrate 14 is parallel to the bias magnet 15, and is arranged so that the center of the substrate 14 coincides with the center of the bias magnet 15. Anisotropic magnetoresistive elements 17, 18, 19, and 20 extending in four regions at the same distance in the XY axis direction from the center of the substrate 14 in a direction that forms an angle of 45 ° (or 135 °) with respect to the axis line. Each is formed.

  FIG. 2B shows a circuit configuration when the anisotropic magnetoresistive elements 17 to 20 are connected. As shown in FIG. 2B, the anisotropic magnetoresistive elements 17 to 20 are connected as a bridge circuit. These are connected on the sensor inner substrate 14 or the lead frame 16 and become four package terminals, and the number of connections to be connected to the mounting substrate 13 to which the magnetic sensor 11 is fixed can be suppressed. Further, since the anisotropic magnetoresistive element is used, the input resistance between Vcc and Gnd is increased and the flowing current value is decreased, resulting in a reduction in power consumption.

FIG. 3 shows a second embodiment of the present invention, which is different from the first embodiment in the configuration of the anisotropic magnetoresistive element arranged on the sensor inner substrate 14 in the magnetic sensor 11 shown in FIG. It is a thing.
FIG. 3A is a diagram showing the positional relationship between the bias magnet 15 and the anisotropic magnetoresistive element in the magnetic sensor 11. The sensor inner substrate 14 is parallel to the bias magnet 15 and is arranged so that the center of the sensor inner substrate 14 coincides with the center of the bias magnet 15. Each of the four regions having the same distance in the XY axis direction from the center of the sensor inner substrate 14 extends in a direction in which the extending directions are perpendicular to each other and form an angle of 45 ° (or 135 °) with respect to the axis. Two adjacent anisotropic magnetoresistive elements are formed, and a total of eight anisotropic magnetoresistive elements 21a, 21b, 22a, 22b, 23a, 23b, 24a, 24b are formed.

  FIG. 3B shows a circuit configuration when the eight anisotropic magnetoresistive elements (21a-24a, 21b-24b) are connected. Each anisotropic magnetoresistive element is connected on the sensor inner substrate 14 or the lead frame 16, and the number of terminals of the package is six. As shown in FIG. 3 (b), the anisotropic magnetoresistive elements (21a to 24a, 21b to 24b) are configured as Wheatstone bridges, are strong against electrical noise, and can obtain a high output.

  As can be seen from the above description, anisotropic magnetoresistive elements formed in four regions having the same distance in the XY axis direction from the center on the sensor inner substrate 14 shown in the first and second embodiments of the present invention. 8 and FIG. 9 correspond to the four magnetic sensors (33 to 36 or 39 to 42) in the prior art. The anisotropic magnetoresistive element, for example, is formed on the sensor inner substrate 14 by a photolithography process, and the accuracy thereof is on the order of nm, so that there is no positioning error at the time of installation, which is a problem in the prior art, and the mounting substrate It can be seen that the installation accuracy can be improved. It can also be seen that since the anisotropic magnetoresistive elements formed in the four regions are formed simultaneously, the variation in characteristics of the individual elements is extremely small.

Next, the detection principle will be described.
FIGS. 4A and 4B are schematic diagrams showing the generation of magnetic vectors in the moving magnet 12, and FIGS. 5A and 5B show the generation of magnetic vectors in the bias magnet 15. FIG. As can be seen from FIGS. 4 and 5, magnetic vectors are generated radially from the polar magnetic surface. When the moving magnet 12 and the bias magnet 15 face each other with the same polarity, the moving magnet 12 and the bias magnet 15 are parallel to the polar magnetic surface in the vicinity of the bias magnet 15 (magnetic field of the bias magnet> magnetic field of the moving magnet) and are approximately the same size as the bias magnet 15. In the plane coordinates (an anisotropic magnetoresistive element is formed and corresponds to a Si substrate or a glass substrate), a combined magnetic vector of the magnetic vectors of the moving magnet 12 and the bias magnet 15 is generated. The combined magnetic vector in the plane coordinate is accompanied by a synchronous change when the positional relationship between the moving magnet 12 and the bias magnet 15 changes.
Thus, by using not only the moving magnet 12 but also the bias magnet 15 (regardless of the direction of the poles), a change in the resultant magnetic vector accompanying the movement of the moving magnet 12 can be caused. Since the magnetic vector changes greatly compared to the case of only 12, the sensitivity as a magnetic sensor is increased.
Further, when only the moving magnet 12 is used, or when the bias magnet 15 and the moving magnet 12 are used with their opposite poles facing each other, the distance from a distance that is half the radius of the moving magnet 12 has moved. Although the output becomes laterally doubled and the position of further movement cannot be detected, the linear movement until the movement of the moving magnet 12 by the radius is achieved by using the bias magnet 15 and the moving magnet 12 with the same poles facing each other. Therefore, the detection area is expanded. This will be described in detail below.

  FIG. 6 is a schematic diagram showing a change in the resultant magnetic vector when the moving magnet 12 moves in the + X-axis direction on a plane coordinate. FIG. 6A shows a case where the centers of the moving magnet 12 and the bias magnet 15 overlap each other, and the resultant magnetic vector in this case is generated radially from the center. FIG. 6B shows a case where the moving magnet 12 has moved by a distance about half the radius in the + X-axis direction in the plane coordinates, and FIG. 6C shows that the moving magnet 12 is substantially in the + X-axis direction in the plane coordinates. This is a case of moving the distance of the radius. When the moving magnet 12 moves from the state shown in FIG. 6A to the state shown in FIGS. 6B and 6C, the plane coordinates, that is, the XY axes from the center of the sensor inner substrate 14 on which the anisotropic magnetoresistive element is formed. In the combined magnetic vectors in the four regions having the same distance in the direction, the direction (α) of the combined magnetic vector changes in the Y-axis region, and the combined magnetic vector hardly changes in the X-axis region. That is, the movement of the moving magnet 12 in the X-axis direction can be detected in the Y-axis area among the four areas where the anisotropic magnetoresistive element is formed, and the movement of the moving magnet 12 in the Y-axis direction. Can be detected in the X-axis region of the four regions. In other words, even if the moving magnet 12 moves to any position within the radius of the size, the coordinate position can be detected by detecting the change of the combined magnetic vector in the four regions. .

An apparatus was actually constructed according to the example. The constructed apparatus includes a 2 mm × 2 mm Si substrate on which eight anisotropic magnetoresistive elements shown in FIG. 3A are formed, a ferrite sintered material Φ1.5 mm × 0.35 mm as a bias magnet 15, and a moving magnet. No. 12, Φ6 mm × 1 mm, Φ4 mm × 1 mm, and Φ3 mm × 1 mm of ferrite sintered material were used.
FIG. 7A shows an output example of the OutA and OutA ′ signals from the differential amplifier when the moving magnet 12 is moved in the X-axis direction. FIG. 7B shows an output example of the OutB and OutB ′ signals from the differential amplifier when the moving magnet 12 is moved in the Y-axis direction.
It can be confirmed that the outputs corresponding to the movement distances on the X axis and the Y axis are the same. The output curve changes in proportion to the diameter of the moving magnet 12. In other words, the size of the moving magnet 12 becomes a factor of the movable area (detection limit range). Therefore, it is possible to easily change and set the detection area (detection limit range) simply by changing the size of the moving magnet 12.

Since the output curves shown in FIGS. 7A and 7B approximate a sine wave shape, the differential output A of OutA and A ′ and the differential output B of OutB and B ′ are expressed by arcsin (A / A maximum output) and arccos (B / B maximum output), the coordinate position can be detected accurately.
When a moving magnet is operated by a human, the moving direction θ of the moving magnet can be obtained by an arctan (A / B) signal, and the moving speed of the moving magnet is k × (A ² + B ² ) ^{0. .5} signal. By using such a process, it is possible to obtain operability close to that of a human.

  In the first and second embodiments, the example in which the magnetic sensor is configured using four or eight anisotropic magnetoresistive elements has been described, but the present invention is not limited to this. For example, when the direction of movement of the detection target is one direction (for example, only in the X-axis direction), position detection is possible by configuring a bridge circuit with two anisotropic magnetoresistive elements in combination with a fixed resistor. It becomes.

The magnetic coordinate position detection apparatus 10 of this invention is represented, (a) is a perspective view, (b) is a side view. (A) is the schematic diagram which showed the positional relationship of the bias magnet 15 and the anisotropic magnetoresistive elements 17-20 in the magnetic sensor 11, (b) is the said anisotropic magnetoresistive elements 17-20. It is a circuit diagram showing the connection method. FIG. 3 shows another embodiment of the magnetic sensor 11 in the magnetic coordinate position detection apparatus 10 in FIG. 1, wherein (a) is a schematic diagram showing the positional relationship between the bias magnet 15 and the anisotropic magnetoresistive element in the magnetic sensor. It is a figure and (b) is a circuit diagram showing the connection method of the said anisotropic magnetoresistive elements 21a-24a, 21b-24b. 3 is a schematic diagram illustrating generation of a magnetic vector in a moving magnet 12. FIG. 3 is a schematic diagram showing generation of magnetic vectors in the bias magnet 15. FIG. It is the schematic diagram showing the change of the synthetic | combination magnetic vector when the moving magnet 12 moves to + X-axis direction by the plane coordinate. It is an output diagram from the differential amplifier of the OutA and OutA ′ signals when the moving magnet 12 is moved in the X-axis direction, and from the differential amplifier of the OutB and OutB ′ signals when the moving magnet 12 is moved in the Y-axis direction. FIG. 1A and 1B show a basic structure of a position detection device in the prior art, in which FIG. 1A is a side view, FIG. 1B is a perspective view, and FIG. It shows another example of the basic structure of the position detection device in the prior art, (a) is a side view, (b) is a perspective view, (c) is an output diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Magnetic coordinate position detection apparatus, 11 ... Magnetic sensor, 12 ... Moving magnet, 13 ... Mounting board, 14 ... In-sensor board, 15 ... Bias magnet, 16 ... Lead frame, 17-20 ... Anisotropic magnetoresistive element 21a-24a and 21b-24b ... anisotropic magnetoresistive element, 31 ... magnet, 32 ... mounting substrate, 33-36 ... magnetic sensor, 37 ... magnet, 38 ... mounting substrate, 39-42 ... magnetic sensor.

Claims (4)

  A magnetic coordinate position detection apparatus comprising: a moving magnet attached to a detection target and moving within a fixed radius on a plane; and a magnetic sensor for detecting a change in a magnetic vector due to a change in position of the moving magnet, A magnetic coordinate position detecting device, wherein the magnetic sensor is packaged with a plurality of anisotropic magnetoresistive elements formed on a substrate (substrate in the sensor) and a bias magnet.   2. The moving magnet and the bias magnet are magnetized in a direction perpendicular to the plane on which the moving magnet moves, and surfaces facing each other are magnetized to the same polarity. Magnetic coordinate position detection device.   In the magnetic sensor, four regions are formed on the substrate parallel to the magnetic pole surface of the bias magnet at the same distance from the origin on the X and Y axes with the magnetic center of the magnetic pole surface of the bias magnet as the origin. Then, an anisotropic magnetoresistive element extended in a direction forming an angle of 45 ° (or 135 °) with the axis is formed for each of these regions, and is composed of a total of four anisotropic magnetoresistive elements. 3. The magnetic coordinate position detection apparatus according to claim 1, wherein the magnetic coordinate position detection apparatus is a magnetic coordinate position detection apparatus.   In the magnetic sensor, four regions are formed on the substrate parallel to the magnetic pole surface of the bias magnet at the same distance from the origin on the X and Y axes with the magnetic center of the magnetic pole surface of the bias magnet as the origin. In each of the regions, two anisotropic magnetoresistive elements extending in a direction perpendicular to each other and extending in an angle of 45 ° (or 135 °) with the axis are adjacent to each other. 3. The magnetic coordinate position detecting device according to claim 1, wherein the magnetic coordinate position detecting device is formed of a total of eight anisotropic magnetoresistive elements.

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