WO2023190752A1

WO2023190752A1 - Position detection system, magnetic sensor, and sensor block

Info

Publication number: WO2023190752A1
Application number: PCT/JP2023/012967
Authority: WO
Inventors: 和弘尾中; 琢也米山
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2022-03-31
Filing date: 2023-03-29
Publication date: 2023-10-05
Also published as: JP2023151542A

Abstract

The present disclosure addresses the problem of improving the position detection. A position detection system (1) is provided with a coil (3) and a magnet (2), and also a magnetic sensor (4). The coil (3) and the magnet (2) move relatively due to magnetic interaction. The magnetic sensor (4) detects the relative movement positions of the coil (3) and the magnet (2). The magnetic sensor (4) includes a first magnetoresistive element having a first principal surface (411) and a second magnetoresistive element having a second principal surface (421). The first principal surface (411) and the second principal surface (421) are arranged side by side in a relative movement direction in which the coil (3) and the magnet (2) move relatively. A normal line (Ax1) of the first principal surface (411) and a normal line (Ax1) of the second principal surface (421) are parallel to the relative movement direction.

Description

Position sensing system, magnetic sensor and sensor block

The present disclosure generally relates to a position sensing system, a magnetic sensor, and a sensor block, and more particularly to a position sensing system, a magnetic sensor, and a sensor block that detect the relative movement position of a coil and a magnet.

Patent Document 1 describes a pointing device used in a mobile device. The pointing device described in Patent Document 1 detects the position of a ferrite magnet based on the difference in output between two Hall elements.

Japanese Patent Application Publication No. 2003-318459

By the way, it is desired to improve the accuracy of position detection in a pointing device (position detection system) as described in Patent Document 1.

The present disclosure has been made in view of the above reasons, and aims to provide a position detection system, a magnetic sensor, and a sensor block that can improve the accuracy of position detection.

A position detection system according to one aspect of the present disclosure includes a coil, a magnet, and a magnetic sensor. The coil and the magnet move relative to each other due to magnetic interaction. The magnetic sensor detects relative movement positions of the coil and the magnet. The magnetic sensor includes a first magnetoresistive element having a first main surface and a second magnetoresistive element having a second main surface. The first main surface and the second main surface are aligned in a relative movement direction, which is a direction in which the coil and the magnet move relative to each other. A normal to the first main surface and a normal to the second main surface are parallel to the relative movement direction.

A magnetic sensor according to one aspect of the present disclosure detects the relative movement position of a coil and a magnet that move relative to each other due to magnetic interaction. The magnetic sensor includes a first magnetoresistive element having a first main surface and a second magnetoresistive element having a second main surface. The first main surface and the second main surface are aligned in a relative movement direction in which the coil and the magnet move relative to each other. A normal to the first main surface and a normal to the second main surface are parallel to the relative movement direction.

A sensor block according to one aspect of the present disclosure is a sensor block used for a magnetic sensor. The magnetic sensor detects a relative movement position of the coil and the magnet in a position detection system including a coil and a magnet that move relative to each other due to magnetic interaction. The sensor block includes a base material and a magnetoresistive element. The base material has electrical insulation properties. The magnetoresistive element is provided on the base material and has a main surface. A normal to the main surface of the magnetoresistive element is parallel to a direction of relative movement in which the coil and the magnet move relative to each other.

FIG. 1A is a front view of a position detection system according to an embodiment. FIG. 1B is a side view of the position detection system according to the above. FIG. 2 is a perspective view of the magnetic sensor according to the embodiment. FIG. 3A is a front view of the magnetic sensor same as above. FIG. 3B is a rear view of the magnetic sensor same as above. FIG. 4 is a block diagram showing a processing unit included in the above position detection system. FIG. 5 is an explanatory diagram showing an example of the relationship between relative movement position and magnetic field strength in the position detection system as described above. FIG. 6 is an explanatory diagram showing another example of the relationship between the relative movement position and the magnetic field strength in the position detection system as described above. FIG. 7 is an explanatory diagram showing still another example of the relationship between the relative movement position and the magnetic field strength in the position detection system as described above. FIG. 8 is a graph showing the relationship between relative movement position and output in the position detection system as described above. FIG. 9 is a graph showing the output characteristics of the above magnetic sensor and the output characteristics of a magnetic sensor using a GaAs-based Hall element.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. Note that in the embodiments described below, elements that are common to each other are given the same reference numerals, and overlapping explanations of the elements that are common may be omitted. The following embodiment is only one of various embodiments of the present disclosure. The embodiments can be modified in various ways depending on the design, etc., as long as the objective of the present disclosure can be achieved. Each figure described in this disclosure is a schematic diagram, and the respective ratios of the sizes and thicknesses of each component in each figure do not necessarily reflect the actual dimensional ratios. Note that the X axis, Y axis, and Z axis in the drawings are orthogonal to each other. The X-axis, Y-axis, and Z-axis in the drawings are merely examples, and are not intended to define the directions in which the position detection system 1 is used. Further, the X-axis, Y-axis, and Z-axis in the drawings are only shown for explanation and have no substance.

Note that "orthogonal (perpendicular)" in the present disclosure includes not only a state in which the angle between the two is strictly 90 degrees, but also a state in which the two intersect within a certain error range. That is, the angle between the two orthogonal angles falls within a certain amount of difference (for example, 10 degrees or less) from 90 degrees. That is, "orthogonal" as used in the present disclosure includes cases where the angle between the two is 80 degrees or more and 100 degrees or less. Similarly, "parallel" in the present disclosure includes not only a state in which the two do not strictly intersect, but also a state in which the two intersect within a certain degree of difference. For example, "parallel" as used in the present disclosure includes an inclination of one to the other of 10 degrees or less. That is, "parallel" as used in the present disclosure includes cases where the angle between one side and the other is -10 degrees or more and 10 degrees or less.

(1) Overview First, an overview of the position detection system 1 according to the present embodiment will be described with reference to FIGS. 1A, 1B, and 2.

The position detection system 1 of this embodiment is used for, for example, a motor. The motor is used, for example, to adjust the focus of a built-in camera (camera module) of a mobile terminal such as a smartphone. The motor is, for example, a VCM (Voice Coil Motor).

As shown in FIGS. 1A and 1B, the position detection system 1 of this embodiment includes a magnet 2, a coil 3, and a magnetic sensor 4.

The coil 3 and the magnet 2 move relative to each other due to the magnetic interaction between the coil 3 and the magnet 2. “Magnetic interaction” in the present disclosure means interaction between the magnetic field generated from the magnet 2 and the magnetic field generated from the coil 3. In addition, "relative movement" refers to the movement of one of two objects relative to the other, the movement of the other of two objects relative to one, and the movement of two objects relative to each other. may be included. The relative movement direction in this embodiment is along the X axis (straight line). In this embodiment, a case is illustrated in which the position of the coil 3 is fixed and the magnet 2 moves relative to the coil 3. In addition, the magnet 2 of this embodiment has a relative movement that is the center of the first end A1 and the second end A2 in the relative movement direction in the relative movement area from the first end A1 to the second end A2 in the relative movement direction. Move based on the center A0 of the area. In the example of FIG. 1B, the moving direction of the magnet 2 is shown by a white arrow.

The magnetic sensor 4 detects the relative movement position of the coil 3 and magnet 2. The magnetic sensor 4 includes a first magnetoresistive element 401 (see FIG. 2) and a second magnetoresistive element 402 (see FIG. 2). “Detecting the relative movement position” in the present disclosure refers to detecting the magnitude (distance) of the relative movement between the coil 3 and the magnet 2, and detecting the relative movement position of the coil 3 and the magnet 2. may be included.

The first magnetoresistive element 401 has a first main surface 411. Further, the second magnetoresistive element 402 has a second main surface 421.

The "first principal surface and second principal surface" in the present disclosure are surfaces formed so as to change the electrical resistance value according to the strength of the magnetic field (change in magnetic field strength) at least along the Z-axis direction. . The first main surface 411 and the second main surface 421 of this embodiment are surfaces parallel to the Z axis (orthogonal to the relative movement direction and the direction in which the magnet 2 and the magnetic sensor 4 are lined up) and the Y axis. In other words, the first main surface 411 and the second main surface 421 are surfaces parallel to the YZ plane. By making the first main surface 411 and the second main surface 421 parallel to the YZ plane, the first magnetoresistive element 401 and the second magnetoresistive element 402 can efficiently control the strength of the magnetic field along the Z-axis direction. Can be detected.

The first main surface 411 of the first magnetoresistive element 401 and the second main surface 421 of the second magnetoresistive element 402 are arranged in the relative movement direction (along the X axis), which is the direction in which the coil 3 and the magnet 2 move relative to each other. ) lined up. The normal Ax1 to the first main surface 411 of the first magnetoresistive element 401 and the normal Ax1 to the second main surface 421 of the second magnetoresistive element 402 are parallel to the relative movement direction (X-axis).

The first main surface 411 and the second main surface 421 are lined up in the direction of relative movement, and the normal Ax1 is parallel to the direction of relative movement. Even if there is a sensor block, the positions of the coil 3 and magnet 2 can be detected using the sensor block. Further, since the output change of the sensor block with respect to the change in magnetic field strength exhibits excellent linearity, the accuracy of position detection can be improved.

(2) Details Hereinafter, the detailed configuration of the position detection system 1 according to the present embodiment will be described with reference to FIGS. 1A to 4.

(2.1) Configuration of position detection system As shown in FIGS. 1A and 1B, the position detection system 1 includes a magnet 2, a coil 3, a magnetic sensor 4, and a processing section 5 (see FIG. 4). Be prepared. In this embodiment, a case will be exemplified in which the position detection system 1 is used for VCM, and the VCM is used for focus adjustment of a camera module. More specifically, in this embodiment, a case is illustrated in which the magnet 2 is fixed to the lens of a camera module, and the coil 3 is fixed to the main body of the camera module.

(2.2) Coil Configuration The coil 3 includes a conductive wire made of, for example, copper, wound around a winding axis along the Z-axis. The coil 3 is arranged in line with the magnet 2 in the Z-axis direction. In other words, the coil 3 and the magnet 2 overlap in plan view from the Z-axis direction. Note that in the Z-axis direction, the direction from the magnet 2 toward the coil 3 is the positive direction of the Z-axis.

In this embodiment, in the default state in which the magnet 2 is not moving relative to the coil 3 (power is not supplied to the coil 3), the position of the winding axis of the coil 3 in the XY plane and the position in the XY plane The position of the center of the magnet 2 coincides with the center position of the magnet 2.

The coil 3 generates a magnetic field when, for example, power is supplied from a power supply circuit. Due to the interaction between the magnetic field generated from the coil 3 and the magnetic field generated from the magnet 2, the magnet 2 moves relative to the coil 3 along the X-axis direction. In other words, in this embodiment, the coil 3 functions as a drive unit that drives (moves) the magnet 2.

Furthermore, the coil 3 of this embodiment moves the magnet 2 in the positive direction of the X-axis and in the negative direction of the X-axis by switching the direction of the current flowing through the coil 3. Specifically, the coil 3 of this embodiment moves the magnet 2 from the center A0 of the relative movement area to a predetermined distance (second end A2) in the positive direction of the X axis, and The magnet 2 can be moved from A0 to a predetermined distance (first end A1) in the negative direction of the X axis. In this embodiment, the predetermined distance is 0.5 mm. That is, the relative movement area is 1.0 mm from -0.5 mm (first end A1) to +0.5 mm (second end A2). In this embodiment, in a plan view from the Z-axis direction, the center A0 of the relative movement area, the position of the winding axis of the coil 3 (the center of the coil 3), the center of the magnet 2, and the center of the magnetic sensor 4 are in agreement.

In this embodiment, the focus adjustment function is realized by moving the lens as the magnet 2 moves in the positive direction of the X-axis and in the negative direction of the X-axis.

(2.3) Structure of Magnet As shown in FIGS. 1A and 1B, the magnet 2 is a monopolar magnet with one end in the X-axis direction having a north pole and the other end having a south pole. The magnet 2 is, for example, a neodymium magnet.

The magnet 2 is formed into a rectangular flat plate. The thickness direction of the magnet 2 is along the Z-axis direction. Further, the longitudinal direction of the magnet 2 is along the magnetization direction of the magnet 2. The "magnetization direction" in the present disclosure is a direction along the straight line connecting the north pole and the south pole. The longitudinal direction (magnetization direction) of the magnet 2 is along the relative movement direction (X-axis).

Further, the magnet 2 has a magnetized surface (opposing surface) 20. The opposing surface 20 is a surface that faces the coil 3 and the magnetic sensor 4 in the Z-axis direction. The normal to the opposing surface 20 is parallel to the Z axis. Further, the magnet 2 has a first surface 21 and a second surface 22. The first surface 21 and the second surface 22 are lined up in the direction of relative movement. The first surface 21 and the second surface 22 are orthogonal to the opposing surface 20. The normals of the first surface 21 and the second surface 22 are parallel to the direction of relative movement. The direction from the first surface 21 to the second surface 22 is the positive direction of the X-axis.

In the following description, the state in which the first surface 21 is located at the first end A1 of the relative movement area is defined as the state in which the magnet 2 is located at the first end A1 of the relative movement area. Further, the state in which the second surface 22 is located at the second end A2 of the relative movement area is defined as the state in which the magnet 2 is located at the second end A2 of the relative movement area. Further, a state in which the center of the first surface 21 and the second surface 22 in the relative movement direction is located at the center A0 of the relative movement area is defined as a state in which the magnet 2 is located at the center A0 of the relative movement area.

(2.4) Configuration of Magnetic Sensor As described above, the magnetic sensor 4 detects the relative movement position of the coil 3 and the magnet 2. The magnetic sensor 4 of this embodiment detects the relative movement position of the coil 3 and the magnet 2 by detecting the amount of displacement of the magnet 2 along the X-axis from the center A0 of the relative movement area. More specifically, the magnetic sensor 4 of this embodiment detects the magnetic field strength (change in magnetic field strength) along the Z-axis direction (the direction in which the magnet 2 and the magnetic sensor 4 are lined up orthogonal to the relative movement direction). In this way, the amount of displacement of the magnet 2 along the X-axis from the center A0 of the relative movement area is detected.

The magnetic sensor 4 is fixed to the coil 3. As shown in FIGS. 1A and 1B, the magnetic sensor 4 is arranged in line with the magnet 2 in a direction (Z-axis direction) orthogonal to the relative direction. In other words, the magnetic sensor 4 and the magnet 2 overlap in plan view from the Z-axis direction. The magnetic sensor 4 and the coil 3 overlap in plan view from the Y-axis direction. As shown in FIG. 2, the overall shape of the magnetic sensor 4 of this embodiment is a rectangular parallelepiped.

The magnetic sensor 4 includes a first sensor block 41, a second sensor block 42, and a connecting portion 43.

The first sensor block 41 is used for the magnetic sensor 4 that detects the relative movement position of the coil 3 and the magnet 2. The first sensor block 41 of this embodiment has a rectangular parallelepiped shape. As shown in FIGS. 3A and 3B, the first sensor block 41 includes a first magnetoresistive element 401, a base material 410, and two

electrodes

412 and 413.

The shape of the base material 410 of this embodiment is a rectangular parallelepiped. The base material 410 has electrical insulation properties. The base material 410 is formed of, for example, an alumina substrate. Base material 410 has a main surface 4101 and an opposing surface.

The main surface 4101 of the base material 410 is formed at one end of the base material 410 in the relative movement direction. The main surface 4101 of the base material 410 has a rectangular shape. The normal line Ax1 to the main surface 4101 of the base material 410 of this embodiment is parallel to the relative movement direction.

The facing surface of the base material 410 faces the facing surface 20 of the magnet 2 in the Z-axis direction. The shape of the opposing surface of the base material 410 is rectangular. The opposing surface of the base material 410 is parallel to the opposing surface 20 of the magnet 2. The opposing surface of the base material 410 is a surface adjacent to the main surface 4101 of the base material 410.

The first magnetoresistive element 401 is provided at one end of the first sensor block 41 in the relative movement direction. In other words, the first magnetoresistive element 401 is provided on the main surface 4101 of the base material 410. The first magnetoresistive element 401 is a rectangular flat plate. The first magnetoresistive element 401 is arranged perpendicular to the facing surface 20 of the magnet 2 .

The first magnetoresistive element 401 is a magnetoresistive sensor (MRS). The first magnetoresistive element 401 of this embodiment is a giant magnetoresistive (GMR) element. More specifically, the first magnetoresistive element 401 of this embodiment is a CIP (current in plane) type GMR element.

The first magnetoresistive element 401 has a first main surface 411.

The shape of the first main surface 411 is rectangular. A normal line Ax1 to the first main surface 411 (see FIG. 1A) is parallel to the relative movement direction. Further, the first main surface 411 is perpendicular to the facing surface 20 of the magnet 2 .

The electrical resistance value of the first magnetoresistive element 401 changes depending on the strength of the magnetic field (magnetic field strength) applied to the first main surface 411. The electrical resistance value of the first magnetoresistive element 401 of this embodiment changes depending on the magnetic field strength of at least the component along the Z-axis direction of the magnetic field applied to the first main surface 411. That is, the first magnetoresistive element 401 of this embodiment detects the magnetic field strength of at least the component along the Z-axis direction of the magnetic field applied to the first main surface 411. In other words, the first magnetoresistive element 401 detects the strength of the magnetic field along the direction (Z-axis direction) in which the magnet 2 and the magnetic sensor 4 are lined up, which is a direction perpendicular to the direction of relative movement.

The two

electrodes

412 and 413 of this embodiment are provided on opposing surfaces of the base material 410. However, the two

electrodes

412 and 413 may be provided on other surfaces of the base material 410.

The two

electrodes

412 and 413 are made of copper or the like, for example. The electrode 412 of this embodiment is an electrode (terminal) for electrically connecting the high potential side circuit of the power source (power supply section) and the first sensor block 41 (first magnetoresistive element 401) (Fig. 4 reference). The electrode 413 of this embodiment is an electrode for electrically connecting the first sensor block 41 (first magnetoresistive element 401) and the processing section 5 (see FIG. 4). Note that "electrically connected" in the present disclosure means a connection in an electrically conductive state, and includes not only a direct connection but also an indirect connection via a conductor such as an electric wire.

The second sensor block 42 is used for the magnetic sensor 4 that detects the relative movement position of the coil 3 and magnet 2. The shape of the second sensor block 42 of this embodiment is a rectangular parallelepiped. As shown in FIGS. 3A and 3B, the second sensor block 42 includes a second magnetoresistive element 402, a base material 410, and two

electrodes

422 and 423.

The shape of the base material 420 of this embodiment is a rectangular parallelepiped. The base material 420 has electrical insulation properties. The base material 420 is formed of, for example, an alumina substrate. Base material 420 has a main surface 4201 and an opposing surface.

The main surface 4201 of the base material 420 is formed at one end of the base material 420 in the relative movement direction. The main surface 4201 of the base material 420 has a rectangular shape. The normal line Ax1 to the main surface 4201 of the base material 420 of this embodiment is parallel to the relative movement direction.

The opposing surface of the base material 420 faces the opposing surface 20 of the magnet 2 in the Z-axis direction. The opposing surface of the base material 420 has a rectangular shape. The opposing surface of the base material 420 is parallel to the opposing surface 20 of the magnet 2. The opposing surface of the base material 420 is a surface adjacent to the main surface 4201 of the base material 420. The normal to the opposing surface of the base material 420 is orthogonal to the normal to the main surface 4201 of the base material 420. Note that the facing surface of the base material 420 of the second sensor block 42 and the facing surface of the base material 410 of the first sensor block 41 are included in the same virtual plane.

The second magnetoresistive element 402 is provided at one end of the second sensor block 42 in the relative movement direction. In other words, the second magnetoresistive element 402 is provided on the main surface 4201 of the base material 420. The second magnetoresistive element 402 is a rectangular flat plate. The second magnetoresistive element 402 is arranged perpendicular to the facing surface 20 of the magnet 2 .

The second magnetoresistive element 402 is a magnetoresistive element (MRS). The second magnetoresistive element 402 of this embodiment is a giant magnetoresistive element (GMR element). More specifically, the second magnetoresistive element 402 of this embodiment is a CIP type GMR element.

The second magnetoresistive element 402 has a second main surface 421.

The shape of the second main surface 421 is rectangular. A normal line Ax1 to the second main surface 421 (see FIG. 1A) is parallel to the relative movement direction. That is, the second main surface 421 is a surface parallel to the first main surface 411 of the first magnetoresistive element 401. Further, the second main surface 421 is perpendicular to the facing surface 20 of the magnet 2 .

The second main surface 421 of this embodiment has the same shape and the same size as the first main surface 411 of the first magnetoresistive element 401. In other words, the first principal surface 411 and the second principal surface 421 are congruent in plan view. Further, the normal Ax1 at the center of the second main surface 421 of the second magnetoresistive element 402 of this embodiment matches the normal Ax1 at the center of the first main surface 411 of the first magnetoresistive element 401. By aligning the normal Ax1 at the center of the first main surface 411 with the normal Ax1 at the center of the second main surface 421, the positions of the first main surface 411 and the second main surface 421 with respect to the magnet 2 can be aligned. I can do it. By aligning the positions of the first main surface 411 and the second main surface 421 with respect to the magnet 2, the accuracy of position detection of the magnetic sensor 4 can be improved.

Further, as shown in FIG. 1B, the second main surface 421 is connected to the first main surface 411 of the first magnetoresistive element 401 with respect to the center A0 of the relative movement area of the coil 3 and the magnet 2 in the relative movement direction. They are arranged symmetrically. In other words, the first distance X11 between the center A0 of the relative movement area of the coil 3 and the magnet 2 in the relative movement direction and the first main surface 411 of the first magnetoresistive element 401, and the relative movement area in the relative movement direction. The second distance X12 between the center A0 and the second main surface 421 of the second magnetoresistive element 402 is equal. By arranging the first main surface 411 and the second main surface 421 symmetrically with respect to the center A0 of the relative movement area in the relative movement direction, the positions of the first main surface 411 and the second main surface 421 with respect to the relative movement area can be adjusted. can be arranged. By aligning the positions of the first main surface 411 and the second main surface 421 with respect to the relative movement area, the accuracy of position detection of the magnetic sensor 4 can be improved.

The electrical resistance value of the second magnetoresistive element 402 changes depending on the strength of the magnetic field (magnetic field strength) applied to the second main surface 421. The electrical resistance value of the second magnetoresistive element 402 of this embodiment changes depending on the magnetic field strength of at least the component along the Z-axis direction of the magnetic field applied to the second main surface 421. That is, the second magnetoresistive element 402 of this embodiment detects the magnetic field strength of at least the component along the Z-axis direction of the magnetic field applied to the second main surface 421. In other words, the second magnetoresistive element 402 detects the strength of the magnetic field along the direction (Z-axis direction) in which the magnet 2 and the magnetic sensor 4 are lined up, which is a direction perpendicular to the direction of relative movement.

The two

electrodes

422 and 423 of this embodiment are provided on opposing surfaces of the base material 420. However, the two

electrodes

422 and 423 may be provided on other surfaces of the base material 420.

The two

electrodes

422 and 423 are made of copper, for example. As shown in FIG. 4, the electrode 422 of this embodiment is an electrode (terminal) for electrically connecting the second sensor block 42 (second magnetoresistive element 402) and the processing section 5. The electrode 423 of this embodiment is an electrode for electrically connecting the second sensor block 42 (second magnetoresistive element 402) and the low potential side circuit (reference potential circuit) of the power source (power supply unit). . In this embodiment, the reference potential is a ground (GND) potential.

As shown in FIG. 4, the first magnetoresistive element 401 of the first sensor block 41 and the second magnetoresistive element 402 of the second sensor block 42 of this embodiment are half-bridge connected. The electrode 413 of the first sensor block 41 and the electrode 422 of the second sensor block 42 of this embodiment are wired and electrically connected. That is, the high-potential side circuit of the power supply, the first magnetoresistive element 401, the second magnetoresistive element 402, and the low-potential side circuit of the power supply are connected in series. The potential (midpoint potential) of the electrode 413 of the first sensor block 41 (the electrode 422 of the second sensor block 42) becomes the output signal Vo1 output by the magnetic sensor 4.

The connecting portion 43 is made of, for example, epoxy resin or polyimide. The connecting portion 43 has electrical insulation properties. The shape of the connecting portion 43 is a rectangular parallelepiped. The connecting portion 43 connects the first sensor block 41 and the second sensor block 42. The connecting portion 43 has a first end 431 in the relative movement direction and a second end 432 located on the opposite side of the first end 431 in the relative movement direction. Note that the first end 431 and the second end 432 in this embodiment are rectangular planes. The other end of the base material 410 of the first sensor block 41 in the relative movement direction is connected to the first end 431 . The other end of the base material 420 of the second sensor block 42 in the relative movement direction is connected to the second end 432 . In other words, the first sensor block 41 is provided at the first end 431 of the connecting portion 43. The second sensor block 42 is provided at the second end 432 of the connecting portion 43. By connecting the first sensor block 41 and the second sensor block 42 with the connecting portion 43, the first sensor block 41 and the second sensor block 42 can be integrated.

That is, the first main surface 411 of the first magnetoresistive element 401 is provided at one end of the magnetic sensor 4 in the relative movement direction (X-axis direction), and the second magnetoresistive element 402 is provided at the other end of the magnetic sensor 4 in the relative movement direction. A second main surface 421 is provided. The distance X1 between the first main surface 411 of the first sensor block 41 and the second main surface 421 of the second sensor block 42 in the relative movement direction is equal to the relative movement area of the coil 3 and the magnet 2. That is, the distance X1 in this embodiment is 1.0 mm. Note that the distance X1 in this embodiment is the sum of the first distance X11 and the second distance X12. By making the distance X1 along the relative movement direction between the first main surface 411 and the second main surface 421 equal to the relative movement area of the coil 3 and the magnet 2, the accuracy of position detection can be further improved. .

(2.5) Configuration of Processing Unit The processing unit 5 shown in FIG. 4 detects the relative movement position of the coil 3 and the magnet 2 by processing the output signal Vo1 of the magnetic sensor 4. The position detection system 1 of this embodiment can detect the relative movement position of the coil 3 and the magnet 2 by processing the output signal Vo1 of the magnetic sensor 4.

More specifically, the processing unit 5 of the present embodiment generates a potential at a connection point between the first magnetoresistive element 401 of the first sensor block 41 and the second magnetoresistive element 402 of the second sensor block 42 (midpoint potential ) is processed as the output signal Vo1 from the magnetic sensor 4.

As shown in FIG. 4, the processing unit 5 of this embodiment includes an amplifier 51 and a microcomputer 52.

The amplifier 51 is electrically connected to the magnetic sensor 4. The amplifier 51 amplifies the output signal Vo1 output from the magnetic sensor 4 and outputs the output signal Vo2 to the microcomputer 52.

The microcomputer 52 detects the relative movement position of the coil 3 and the magnet 2 by processing the output signal Vo2 output by the amplifier 51.

(3) Effects Next, the effects of the position detection system 1 of this embodiment will be described with reference to FIGS. 5 to 9. In the following description, if the first magnetoresistive element 401 and the second magnetoresistive element 402 are not distinguished, each of the first magnetoresistive element 401 and the second magnetoresistive element 402 will be simply referred to as a "magnetoresistive element". Sometimes. Furthermore, when the first principal surface 411 and the second principal surface 421 are not distinguished from each other, each of the first principal surface 411 and the second principal surface 421 may be simply referred to as a "principal surface."

The graph G1 shown in FIGS. 5 to 7 shows the relative movement position of the coil 3 and the magnet 2 based on the center A0 of the relative movement area in the relative movement direction, and the relative movement position of the coil 3 and the magnet 2, and the applied voltage to the first main surface 411 or the second main surface 421. FIG.

In this embodiment, the coil 3 and the magnetic sensor 4 are fixed, and the magnet 2 moves relative to the coil 3 and the magnetic sensor 4. However, even if the magnet 2 is fixed and the coil 3 and magnetic sensor 4 move relative to the magnet 2, the position detection system 1 cannot detect the relative movement position of the magnet 2 and the coil 3. can. Here, in the following explanation, the effects of the position detection system 1 will be explained assuming that the magnet 2 is fixed and the coil 3 and the magnetic sensor 4 move relative to the magnet 2.

In the example of FIG. 5, the first main surface 411 is at a position of -0.5 mm with respect to the center A0 (0 mm) of the relative movement area, and the second main surface 421 is located at a position of +0.5 mm with respect to the center of the relative movement area. The example shows the case where the magnet 2 is located at the center A0 of the relative movement area. Note that the position -0.5 mm in FIGS. 5 to 7 is a position 0.5 mm away from the center A0 of the relative movement area on the positive side of the X axis. The +0.5 mm position in FIGS. 5 to 7 is a position 0.5 mm away from the center A0 of the relative movement area on the negative side of the X axis.

Similarly, in the example of FIG. 6, when the first main surface 411 is at a position of -1.0 mm with respect to the center A0 of the relative movement area, and the second main surface 421 is at the center A0 of the relative movement area (magnet 2 is located at the first end A1 of the relative movement area). In addition, in the example of FIG. 7, when the first main surface 411 is located at the center A0 of the relative movement area and the second main surface 421 is located at a position of +1.0 mm with respect to the center A0 of the relative movement area (the magnet 2 A state in which the robot is located at the second end A2 of the relative movement area) is illustrated.

As shown in FIGS. 5 to 7, the magnetic field strength detected by the magnetoresistive element becomes stronger as the magnetoresistive element (principal surface) moves away from the center A0 of the relative movement area (as the absolute value of the position in graph G1 increases). Become. For example, as shown in FIG. 6, when the second main surface 421 is located at the center A0 of the relative movement area, the magnetic field strength detected by the second main surface 421 is zero.

The sensor block (magnetoresistive element) cannot detect differences in the direction of the magnetic field in the Z-axis direction. Therefore, as shown in FIGS. 5 to 7, the graph G1 is symmetrical with respect to the center A0 of the relative movement area. Therefore, when the magnetic sensor 4 has only one sensor block having a magnetoresistive element, the magnetic sensor 4 is located on the positive side of the X axis or on the negative side with respect to the center A0 of the relative movement area. It is not possible to distinguish between the two locations.

Here, the magnetic sensor 4 of this embodiment includes a first sensor block 41 having a first magnetoresistive element 401 and a second sensor block 42 having a second magnetoresistive element 402. Further, the first main surface 411 of the first magnetoresistive element 401 and the second main surface 421 of the second magnetoresistive element 402 are aligned in the relative movement direction. In the position detection system 1 of this embodiment, the relative movement position of the coil 3 and the magnet 2 is detected regardless of whether the coil 3 and the magnet 2 move relative to each other in either the positive direction or the negative direction in the relative movement direction. be able to.

The first magnetoresistive element 401 of the first sensor block 41 and the second magnetoresistive element 402 of the second sensor block 42 are half-bridge connected, and the processing section 5 connects the first magnetoresistive element 401 and the second magnetoresistive element 402 to each other. The potential at the connection point with the resistance element 402 is processed as an output signal. Therefore, in the position detection system 1 of this embodiment, the relative movement position of the coil 3 and the magnet 2 can be detected with a simple circuit configuration. In addition, since the processing unit 5 processes the potential at the connection point between the first magnetoresistive element 401 and the second magnetoresistive element 402 as an output signal, noise components can be canceled and the S/N ratio can be improved.

Furthermore, as shown in FIGS. 5 to 7, when the position of the graph G1 changes, the slope of the tangent to the graph G1 changes. In the position range of 0 mm to +1 mm, the graph G1 is a gentle S-shaped curve. Moreover, in the range of the position from −1.0 mm to 0 mm, the graph G1 is a curve that is a left-right inversion of a gentle S-shape (inverted S-shape). That is, since the magnetic field strength detected by the magnetoresistive element does not change linearly with respect to positional changes, it affects the linearity of the output of the magnetic sensor 4 with respect to changes in the magnetic field strength.

Here, in the position detection system 1 of this embodiment, the first distance X11 between the center A0 of the relative movement area in the relative movement direction and the first main surface 411 of the first magnetoresistive element 401, and The second distance X12 between the center A0 of the relative movement area and the second main surface 421 of the second magnetoresistive element 402 is equal. That is, the first main surface 411 and the second main surface 421 of this embodiment are arranged symmetrically with respect to the center A0 of the relative movement area. Since the first principal surface 411 and the second principal surface 421 are arranged symmetrically with respect to the center A0 of the relative movement area, the S-shaped (inverted S-shaped) change in magnetic field strength is canceled, and the magnetic field The linearity of the output of the magnetic sensor 4 with respect to changes in intensity is improved.

FIG. 8 shows the relationship between the voltage value of the output signal Vo1 of the magnetic sensor 4 and the relative movement position of the coil 3 and magnet 2 in the position detection system 1 of this embodiment. In the example of FIG. 8, Vcc (high potential side circuit of the power supply) is 3.0V. Point P1 in FIG. 8 indicates the voltage value of the output signal Vo1 of the magnetic sensor 4 when the magnetic sensor 4 is in the position shown in FIG. 5 (the magnet 2 is located at the center A0 of the relative movement area). It is a point. Further, point P2 indicates the voltage value of the output signal Vo1 of the magnetic sensor 4 when the magnetic sensor 4 is in the position shown in FIG. 6 (the state where the magnet 2 is located at the first end A1 of the relative movement area). It is a point. Further, point P3 indicates the voltage value of the output signal Vo1 of the magnetic sensor 4 when the magnetic sensor 4 is in the position shown in FIG. 7 (the state where the magnet 2 is located at the second end A2 of the relative movement area). It is a point. In the example of FIG. 8, the linearity of the change in the voltage value of the output signal Vo1 of the magnetic sensor 4 with respect to the change in the relative movement position of the coil 3 and the magnet 2 is 99.94%, which is good.

FIG. 9 is a graph showing the output characteristics of the magnetic sensor 4 of this embodiment and the output characteristics of the magnetic sensor using a GaAs-based Hall element. In FIG. 9, the center A0 of the relative movement area between the coil 3 and the magnet 2 is 0.5 mm. Graph G2 shows the output characteristics of the magnetic sensor 4 of this embodiment, and graph G3 shows the output characteristics of the magnetic sensor using a GaAs-based Hall element. The first magnetoresistive element 401 and the second magnetoresistive element 402 of this embodiment are CIP type GMR elements. By using the first peak output of the CIP type GMR film, the output signal Vo1 of the magnetic sensor 4 of this embodiment has an output voltage 4 times or more larger and an accuracy 10 times or more higher than that of a GaAs-based Hall element. improves.

(4) Modification Examples Modification examples of the above embodiment will be listed below. The modified examples described below can be applied in combination as appropriate.

The magnet 2 is not limited to a single-pole magnet, but may be a multi-pole magnet in which north poles and south poles are alternately arranged.

The first magnetoresistive element 401 and the second magnetoresistive element 402 are not limited to GMR elements, but may be tunnel magnetoresistive (TMR) elements or anisotropic magnetoresistive (AMR) elements. It's okay.

In the above embodiment, the position detection system 1 is used for a VCM, but the position detection system 1 may be used for a linear motor other than a VCM. Note that the term "linear motor" as used in the present disclosure means a motor whose relative movement direction is along a straight line.

The magnet 2 may be fixed to the main body of the camera module, and the coil 3 may be fixed to the lens of the camera module. If the magnet 2 is fixed to the main body of the camera module and the coil 3 is fixed to the lens of the camera module, for example, the magnet 2 does not move and the coil 3 moves relative to the magnet 2.

In the above embodiment, the relative movement area between the coil 3 and the magnet 2 is 1.0 mm, but the relative movement area between the coil 3 and the magnet 2 may be less than 1.0 mm, or 1.0 mm. It may be more than that. For example, the relative movement area between the coil 3 and the magnet 2 may be 2.0 mm. When the relative movement area of the coil 3 and the magnet 2 is 2.0 mm, it is preferable that the distance X1 between the first main surface 411 and the second main surface 421 in the relative movement direction is 2.0 mm.

(summary)
As explained above, the position detection system (1) according to the first aspect includes a coil (3), a magnet (2), and a magnetic sensor (4). The coil (3) and the magnet (2) move relative to each other due to magnetic interaction. The magnetic sensor (4) detects the relative movement position of the coil (3) and the magnet (2). The magnetic sensor (4) includes a first magnetoresistive element (401) having a first main surface (411) and a second magnetoresistive element (402) having a second main surface (421). The first main surface (411) and the second main surface (421) are lined up in the relative movement direction, which is the direction in which the coil (3) and the magnet (2) move relative to each other. The normal (Ax1) to the first main surface (411) and the normal (Ax1) to the second main surface (421) are parallel to the relative movement direction.

According to this aspect, the first main surface (411) and the second main surface (421) are lined up in the direction of relative movement, and the normal (Ax1) is parallel to the direction of relative movement. ) and the magnet (2) move relative to each other so as to vibrate, the sensor block can be used to detect the position of the coil (3) and the magnet (2). Further, since the output change of the sensor block with respect to the change in magnetic field strength exhibits excellent linearity, the accuracy of position detection can be improved.

In the position detection system (1) according to the second aspect, in the first aspect, the relative movement direction of the coil (3) and the magnet (2) is along a straight line. The first distance (X11) and the second distance (X12) are equal. The first distance (X11) is between the center (A0) of the relative movement area of the coil (3) and the magnet (2) in the relative movement direction and the first principal surface (411) of the first magnetoresistive element (401). is the distance. The second distance (X12) is the distance between the center (A0) of the relative movement area in the relative movement direction and the second main surface (421) of the second magnetoresistive element (402).

According to this aspect, by arranging the first main surface (411) and the second main surface (421) symmetrically with respect to the center of the relative movement direction in the relative movement direction, the first main surface with respect to the relative movement area (411) and the second principal surface (421) can be aligned. By aligning the positions of the first main surface (411) and the second main surface (421) with respect to the relative movement area, the accuracy of position detection of the magnetic sensor (4) can be improved.

In the position detection system (1) according to the third aspect, in the first or second aspect, the first principal surface (411) of the first magnetoresistive element (401) and the second magnetoresistive element ( 402) and the second main surface (421) is equal to the relative movement area of the coil (3) and the magnet (2).

According to this aspect, the distance (X1) between the first main surface (411) and the second main surface (421) in the relative movement direction and the relative movement area of the coil (3) and the magnet (2) are Since they are equal, the accuracy of position detection can be further improved.

In the position detection system (1) according to the fourth aspect, in any of the first to third aspects, the normal (Ax1) at the center of the first main surface (411) of the first magnetoresistive element (401) and the normal line (Ax1) at the center of the second principal surface (421) of the second magnetoresistive element (402) coincide with each other.

According to this aspect, by making the normal (Ax1) at the center of the first main surface (411) and the normal (Ax1) at the center of the second main surface (421) coincident, The positions of the first main surface (411) and the second main surface (421) can be aligned. By aligning the first main surface (411) and the second main surface (421) with respect to the magnet (2), the accuracy of position detection of the magnetic sensor (4) can be improved.

In the position detection system (1) according to the fifth aspect, in any one of the first to fourth aspects, the first magnetoresistive element (401) and the second magnetoresistive element (402) are giant magnetoresistive elements. It is.

According to this aspect, by using the first peak output of the GMR film, the output voltage of the output signal (Vo1) of the magnetic sensor (4) is made four times or more larger than that of the GaAs-based Hall element, and the output signal (Vo1) can be improved by more than 10 times.

The position detection system (1) according to the sixth aspect further includes a processing section (5) in any one of the first to fifth aspects. The processing unit (5) detects the relative movement position by processing the output signal (Vo1) output by the magnetic sensor (4).

According to this aspect, the processing unit (5) processes the output signal (Vo1) output by the magnetic sensor (4), so that the position detection system (1) can detect the relative movement position of.

In the position detection system (1) according to the seventh aspect, in the sixth aspect, the first magnetoresistive element (401) and the second magnetoresistive element (402) are half-bridge connected. The processing unit (5) uses the potential at the connection point between the first magnetoresistive element (401) and the second magnetoresistive element (402) as an output signal (Vo1).

According to this aspect, the relative movement position of the coil (3) and the magnet (2) can be detected with a simple circuit configuration.

In the position detection system (1) according to the eighth aspect, in any one of the first to seventh aspects, the magnetic sensor (4) includes a first sensor block (41) and a second sensor block (42). , and a connecting portion (43). The first sensor block (41) includes a first magnetoresistive element (401). The second sensor block (42) includes a second magnetoresistive element (402). The connecting portion (43) connects the first sensor block (41) and the second sensor block (42). The connecting portion (43) has a first end (431) in the relative movement direction and a second end (432) located on the opposite side of the first end (431) in the relative movement direction. The first sensor block (41) is provided at the first end (431). A second sensor block (42) is provided at the second end (432).

According to this aspect, the connecting portion (43) connects the first sensor block (41) and the second sensor block (42), thereby connecting the first sensor block (41) and the second sensor block (42). It can be integrated.

In the position detection system (1) according to the ninth aspect, in any one of the first to eighth aspects, the magnet (2) and the magnetic sensor (4) are aligned in a direction perpendicular to the relative movement direction. . The first magnetoresistive element (401) and the second magnetoresistive element (402) detect the strength of the magnetic field along orthogonal directions.

According to this aspect, the magnetic sensor (4) can detect the strength of the magnetic field in the direction perpendicular to the relative movement direction and in the direction in which the magnet (2) and the magnetic sensor (4) are lined up.

The configurations other than the first aspect are not essential to the position detection system (1) and can be omitted as appropriate.

The magnetic sensor (4) according to the tenth aspect detects the relative movement position of the coil (3) and the magnet (2) that move relative to each other due to magnetic interaction. The magnetic sensor (4) includes a first magnetoresistive element (401) having a first main surface (411) and a second magnetoresistive element (402) having a second main surface (421). The first main surface (411) and the second main surface (421) are lined up in the relative movement direction in which the coil (3) and the magnet (2) move relative to each other. The normal (Ax1) to the first main surface (411) and the normal (Ax1) to the second main surface (421) are parallel to the relative movement direction.

The sensor block according to the eleventh aspect is a sensor block (first sensor block 41; second sensor block 42) used in the magnetic sensor (4). A magnetic sensor (4) detects the relative movement position of a coil (3) and a magnet (2) in a position detection system (1) that includes a coil (3) and a magnet (2) that move relative to each other due to magnetic interaction. . The sensor block includes a base material (410; 420) and magnetoresistive elements (first magnetoresistive element 401; second magnetoresistive element 402). The base material has electrical insulation properties. The magnetoresistive element is provided on a base material and has main surfaces (first main surface 411; second main surface 421). The normal (Ax1) to the main surface of the magnetoresistive element is parallel to the direction of relative movement, which is the direction in which the coil (3) and the magnet (2) move relative to each other.

According to this aspect, the sensor block can be used, for example, as the first sensor block (41) or the second sensor block (42) of the position detection system (1). In the position detection system (1), the first principal surface (411) and the second principal surface (421) are lined up in the direction of relative movement, and the normal (Ax1) is parallel to the direction of relative movement. Even when the coil (3) and the magnet (2) move relative to each other so as to vibrate, the positions of the coil (3) and the magnet (2) can be detected using the sensor block. Further, since the output change of the sensor block with respect to the change in magnetic field strength exhibits excellent linearity, the accuracy of position detection can be improved.

1 Position detection system 2 Magnet 3 Coil 4 Magnetic sensor 401 First magnetoresistive element (magnetoresistive element)
402 Second magnetoresistive element (magnetoresistive element)
41 First sensor block (sensor block)
410 Base material 411 First main surface (main surface)
42 Second sensor block (sensor block)
420 Base material 421 Second main surface (main surface)
43 Connection section 431 First end 432 Second end 5 Processing section Ax1 Normal line Vo1 Output signal X1 Distance X11 First distance X12 Second distance

Claims

A coil and a magnet that move relative to each other due to magnetic interaction;
a magnetic sensor that detects the relative movement position of the coil and the magnet;
Equipped with
The magnetic sensor is
a first magnetoresistive element having a first main surface;
a second magnetoresistive element having a second principal surface;
has
The first main surface of the first magnetoresistive element and the second main surface of the second magnetoresistive element are aligned in a relative movement direction that is a direction in which the coil and the magnet move relative to each other,
A normal to the first main surface of the first magnetoresistive element and a normal to the second main surface of the second magnetoresistive element are parallel to the relative movement direction.
Location sensing system.
The relative movement direction of the coil and the magnet is along a straight line,
a first distance between the center of the relative movement area of the coil and the magnet in the relative movement direction and the first main surface of the first magnetoresistive element; and a center of the relative movement area in the relative movement direction. a second distance between the second magnetoresistive element and the second principal surface is equal;
The position sensing system according to claim 1.
A distance between the first main surface of the first magnetoresistive element and the second main surface of the second magnetoresistive element in the relative movement direction is equal to a relative movement area of the coil and the magnet. The position detection system according to item 1 or 2.
The normal line at the center of the first main surface of the first magnetoresistive element and the normal line at the center of the second main surface of the second magnetoresistive element match;
The position detection system according to any one of claims 1 to 3.
The first magnetoresistive element and the second magnetoresistive element are giant magnetoresistive elements,
The position detection system according to any one of claims 1 to 4.
further comprising a processing unit that detects the relative movement position by processing an output signal of the magnetic sensor;
The position detection system according to any one of claims 1 to 5.
The first magnetoresistive element and the second magnetoresistive element are half-bridge connected,
The processing unit uses a potential at a connection point between the first magnetoresistive element and the second magnetoresistive element as the output signal.
The position sensing system according to claim 6.
The magnetic sensor is
a first sensor block including the first magnetoresistive element;
a second sensor block including the second magnetoresistive element;
a connection part that connects the first sensor block and the second sensor block;
has
The connection part is
a first end in the relative movement direction;
a second end located on the opposite side of the first end in the relative movement direction;
has
the first sensor block is provided at the first end,
the second sensor block is provided at the second end;
The position detection system according to any one of claims 1 to 7.
The magnet and the magnetic sensor are arranged in a direction perpendicular to the relative movement direction,
The first magnetoresistive element and the second magnetoresistive element detect the intensity of the magnetic field along the orthogonal direction.
The position detection system according to any one of claims 1 to 8.
A magnetic sensor that detects the relative movement position of a coil and a magnet that move relatively due to magnetic interaction,
a first magnetoresistive element having a first main surface;
a second magnetoresistive element having a second principal surface;
Equipped with
The first main surface of the first magnetoresistive element and the second main surface of the second magnetoresistive element are aligned in a relative movement direction in which the coil and the magnet move relative to each other,
A normal to the first main surface of the first magnetoresistive element and a normal to the second main surface of the second magnetoresistive element are parallel to the relative movement direction.
magnetic sensor.
In a position detection system including a coil and a magnet that move relative to each other due to magnetic interaction, a sensor block used for a magnetic sensor for detecting the relative movement position of the coil and the magnet,
a base material having electrical insulation;
a magnetoresistive element provided on the base material and having a main surface;
Equipped with
A normal to the main surface of the magnetoresistive element is parallel to a relative movement direction in which the coil and the magnet move relative to each other.
sensor block.