WO2010095495A1 - Magnetism detection device - Google Patents

Abstract

Provided is a magnetism detection device which is thin and is capable of performing highly accurate position detection. Orthogonally-crossed X-axis and Y-axis are respectively provided with a pair of X-axis magnetic sensors (13, 15) and a pair of Y-axis magnetic sensors (12, 14) arranged with the center of intersection therebetween. A magnet (11) is supported to be slidably movable in an X-Y plane surrounded by the X-axis magnetic sensors and the Y-axis magnetic sensors. When the magnet (11) makes a sliding movement in the X-Y plane, on the basis of an electric resistance change of a GMR element in accordance with angle changes of horizontal magnetic fields which flow into the respective magnetic sensors (12 to 15), a position of the magnet (11) can be detected by a differential output of the X-axis magnetic sensors (13, 15) and a differential output of the Y-axis magnetic sensors (12, 14).

Description

Magnetic detection device

The present invention relates to a magnetic detection device provided with a magnet movably supported in an XY plane and a magnetic sensor.

In a slide-type input device mounted on a mobile phone device or a game device, it is necessary to accurately know the movement position of the operating body in the XY plane.

Patent Document 1 discloses an invention related to a pointing device. The pointing device includes a magnet and a magnetic sensor, and detects a change in magnetic flux density flowing into the magnetic sensor as the magnet moves.

And a magnet and a magnetic sensor are installed in the state separated in the height direction, and it is set up so that the magnetic flux density which acts on a magnetic sensor may become large as a magnet approaches directly on a magnetic sensor.

International Publication No. 2002/086694

However, with the above-described structure of the pointing device, it has been difficult to reduce the thickness. In addition, since it is configured to detect a change in magnetic flux density, there is also a problem that it is easily influenced by disturbance noise in a state where the magnetic field is weak, and it is difficult to obtain linear characteristics.

Therefore, the present invention is intended to solve the above-mentioned conventional problems, and in particular, it is an object of the present invention to provide a magnetic detection apparatus capable of performing thin position detection with high accuracy.

The present invention relates to a magnetic detection device having a magnet and a non-contact type magnetic sensor provided with a magnetoresistance effect element whose electric resistance value changes with respect to an external magnetic field,
The magnetoresistance effect element has a laminated structure of a fixed magnetic layer in which the magnetization direction is fixed, and a free magnetic layer which is formed on the fixed magnetic layer via the nonmagnetic layer and in which the magnetization direction changes with respect to the external magnetic field. It is configured to have
A pair of X-axis magnetic sensors and a pair of Y-axis magnetic sensors are disposed on orthogonal X-axis lines and Y-axis lines, respectively, via a cross center.
The magnet is slidably supported in an XY plane surrounded by the X-axis magnetic sensor and the Y-axis magnetic sensor.
When the magnet slides in the XY plane, the differential of the X-axis magnetic sensor is based on the change in electric resistance of the magnetoresistive element with the change in the angle of the horizontal magnetic field flowing into each magnetic sensor. The position of the magnet can be detected by an output and a differential output of the Y-axis magnetic sensor.

In the present invention, a magnet is slidably supported within an XY plane surrounded by a pair of X-axis magnetic sensors and a pair of Y-axis magnetic sensors, and the magnet is horizontal to the magnetoresistive element provided in each magnetic sensor. The magnetic field component is made to flow. And in this invention, the angle change of the horizontal magnetic field from a magnet is detected with a magnetoresistive effect element, and since a magnetic sensor can be arrange | positioned in the substantially side position of a magnet, it can contribute to thickness reduction compared with the former. It has become.

Further, according to the present invention, since the change in angle of the horizontal magnetic field is detected, it is possible to apply a magnetic field large enough to magnetically saturate the magnetoresistive element from the magnet to each magnetic sensor within the entire movement range of the magnet. It is. Thus, disturbance noise can be suppressed, and the linear characteristic can be easily improved.

In the present invention, the pinned magnetic layers of the magnetoresistance effect elements constituting each X axis magnetic sensor are respectively magnetized and fixed in a direction parallel to the Y direction, and the pinned magnetic layers of the magnetoresistance effect elements constituting each Y axis magnetic sensor The layers are preferably fixed in magnetization in a direction parallel to the X direction.

Further, in the present invention, it is preferable that the magnet has a side surface facing each magnetic sensor that is a magnetized surface, because the thickness can be reduced more effectively.

Alternatively, in the present invention, the upper and lower surfaces of the magnet may be magnetized surfaces.

According to the magnetic detection device of the present invention, the thickness can be reduced as compared with the prior art, and the position detection accuracy can be improved.

A perspective view of the magnetic detection device according to the first embodiment; An enlarged side view of the magnetic detection device as viewed in the direction of the arrow in FIG. 1; (A) is a plan view of a magnet and a magnetic sensor showing a reference state, (b) is a plan view when the magnet slides in the Y1 direction from the reference state of (a), (c) is (a) A plan view when the magnet slides in the direction of 45 degrees between the Y1 direction and the X1 direction from the reference state of FIG. 4 is an explanatory view when the magnet shown in FIG. 3C slides in an oblique direction, and FIG. 4A is an enlarged plan view showing the relationship between one X axis magnetic sensor and the magnet, FIG. Is an enlarged plan view showing the relationship between the other X axis magnetic sensor and the magnet 11; FIG. 5 is an explanatory view when the magnet shown in FIG. 3 (c) slides in an oblique direction, and FIG. 5 (a) is an enlarged plan view showing the relationship between one Y-axis magnetic sensor and the magnet; Is an enlarged plan view showing the relationship between the other Y-axis magnetic sensor and the magnet 11; A perspective view of a magnetic detection device according to a second embodiment; An enlarged side view of the magnetic detection device as viewed in the direction of the arrow in FIG. (A) is a plan view of a magnet and a magnetic sensor showing a reference state, (b) is a plan view when the magnet slides in the Y1 direction from the reference state of (a), (c) is (a) A plan view when the magnet slides in the direction of 45 degrees between the Y1 direction and the X1 direction from the reference state of A partial sectional view of the magnetoresistive element, Circuit diagram of the magnetic sensor, A graph showing the relationship between the distance when the magnet is slid in the Y1 direction and the sensor output using the magnetic detection device of the first embodiment, Graph showing the relationship between sensor output and distance when the magnet is slid in the direction of 45 degrees between the Y1 direction and the X1 direction using the magnetic detection device of the first embodiment. When the magnet is axially moved in the Y1 direction (Fig. 11) and when the magnet is moved in the oblique direction (Fig. 12), the relationship between the movement distance in the Y1 direction and the sensor output obtained from each experimental result is Graph showing, A graph showing the relationship between the distance when the magnet is slid in the Y1 direction and the sensor output using the magnetic detection device of the second embodiment, A graph showing the relationship between sensor output and the distance when the magnet is slid in the direction of 45 degrees between the Y1 direction and the X1 direction using the magnetic detection device of the second embodiment. When the magnet is axially moved in the Y1 direction (Fig. 14) and when the magnet is moved in the oblique direction (Fig. 15), the relationship between the movement distance in the Y1 direction and the sensor output obtained from each experimental result is Graph showing,

FIG. 1 is a perspective view of the magnetic detection device according to the first embodiment, FIG. 2 is an enlarged side view of the magnetic detection device as viewed from the arrow direction in FIG. 1, and FIG. 3 (a) is a magnet showing a reference state. 3 (b) is a plan view when the magnet slides in the Y1 direction from the reference state of FIG. 3 (a), and FIG. 3 (c) is a reference of FIG. 3 (a) It is a top view when a magnet slides in the 45 degree direction diagonally between Y1 direction and X1 direction from a state.

As shown in FIG. 1, the magnetic detection device 10 is configured to include a magnet 11 and magnetic sensors 12 to 15. The magnet 11 is supported slidably in the XY plane.

As shown in FIG. 1, the magnet 11 is formed in a disk shape, and the operation body 16 is provided at the center portion thereof. The side face 11a of the magnet 11 shown in FIGS. 1 and 2 is a pole face, and the N pole and the S pole are alternately magnetized at intervals of 90 degrees. As shown in FIG. 1, the notch 11b is provided at the boundary between the N pole and the S pole, but by setting the position of the notch 11b as the boundary between the N pole and the S pole in the magnetizing step The magnetization deviation can be suppressed.

As shown in FIG. 1, four magnetic sensors 12 to 15 are provided on a substrate 17. As shown in FIG. 2, the magnet 11 is supported in a slightly floating state from above the substrate 17. Specifically, the magnet 11 is supported at a distance of about 0.5 to 1.0 mm from the upper surface of the substrate 17. As shown in FIG. 2, the magnetic sensors 12 to 15 are opposed to the side positions of the magnet 11 with an interval. The moving area of the magnet 11 is in the area surrounded by the magnetic sensors 12 to 15, and the magnet 11 and the magnetic sensors 12 to 15 maintain a non-contact state.

As shown in FIG. 1 and FIG. 3, the pair of X-axis magnetic sensors (sensors for detecting Y direction) 13 and 15 are disposed on the X axis along the intersection center O with the Y axis. Further, the pair of Y-axis magnetic sensors (sensors for detecting the X direction) 12 and 14 are disposed on the Y-axis along the intersection center O with the X-axis. The distances between the X axis magnetic sensors 13 and 15 and the Y axis magnetic sensors 12 and 14 and the intersection center O are constant.

As shown in FIGS. 1 and 3, the magnet 11 is supported slidably in the XY plane surrounded by the X-axis magnetic sensors 13 and 15 and the Y-axis magnetic sensors 12 and.

FIGS. 1 and 3A show a reference state in which the center 11 c of the magnet 11 is located at the intersection center O (moving origin). Further, at this time, the direction of the magnet 11 with respect to the magnetic sensors 12 to 15 is regulated such that the centers of the magnetic sensors 12 to 15 face each other in the direction perpendicular to the magnetic poles of the N and S poles of the magnet 11.

Each of the magnetic sensors 12 to 15 has the same configuration including the GMR element 20 whose electric resistance value changes with respect to an external magnetic field.

As shown in FIG. 9, for example, the GMR element 20 is laminated in the order of the antiferromagnetic layer 28, the pinned magnetic layer 29, the nonmagnetic layer 30, the free magnetic layer 31, and the protective layer 32 from the bottom. The antiferromagnetic layer 28 is, for example, IrMn or PtMn. CoFe is preferably used for the pinned magnetic layer 29. The pinned magnetic layer 29 may have a single layer structure of a magnetic layer, but in particular, a laminated ferri structure of magnetic layer / nonmagnetic intermediate layer / magnetic layer is preferable because stabilization of magnetization can be achieved. An exchange coupling magnetic field (Hex) is generated between the pinned magnetic layer 29 and the antiferromagnetic layer 28 by heat treatment in a magnetic field, and the magnetization direction (P direction) of the pinned magnetic layer 29 is fixed in a predetermined direction. The nonmagnetic layer 30 is formed of, for example, Cu. NiFe is preferably used for the free magnetic layer 31. The free magnetic layer 31 is formed of a single layer structure or a laminated structure of the magnetic layer. The magnetization direction (F direction) of the free magnetic layer 31 fluctuates with respect to the external magnetic field. The protective layer 32 is formed of, for example, Ta.

As shown in FIG. 3A, the magnetization direction (P direction) of the pinned magnetic layer 29 of the GMR element 20 provided in the Y-axis magnetic sensor 12 on the upper side in the drawing is the X1 direction. The magnetization direction (P direction) of the pinned magnetic layer of the GMR element 20 provided in the Y-axis magnetic sensor 14 on the lower side in the drawing is the X2 direction. In this embodiment, the pinned magnetic layers 29 of the GMR elements 20 provided in the Y-axis magnetic sensors 12 and 14 are in opposite directions to each other, but may be pinned in the same direction.

As shown in FIG. 3A, the magnetization direction (P direction) of the pinned magnetic layer 29 of the GMR element 20 provided in the X-axis magnetic sensor 13 on the left side in the drawing is the Y2 direction. The magnetization direction (P direction) of the pinned magnetic layer 29 of the GMR element 20 provided in the X-axis magnetic sensor 15 on the right side of the drawing is the Y1 direction. In this embodiment, the pinned magnetic layers 29 of the GMR elements 20 provided in the X-axis magnetic sensors 13 and 15 are in opposite directions to each other, but may be pinned in the same direction.

For example, two GMR elements 20 are provided for each of the magnetic sensors 12 to 15, and as shown in FIG. 10, two GMR elements 20 constituting each of the Y-axis magnetic sensors 12 and 14 have a bridge circuit. Configured. Reference numeral 24 denotes an input terminal, and reference numeral 25 denotes a ground terminal.

As shown in FIG. 10, the bridge circuit is connected to the amplifier 26, and the output terminal 27 is connected to the output side of the amplifier 26.

A GMR element 20 may be provided for each of the magnetic sensors 12 to 15, and a bridge circuit may be formed of the GMR elements 20 constituting the Y-axis magnetic sensors 12 and 14 and a fixed resistance element.

The thick arrows shown in FIG. 3A indicate the direction of the horizontal magnetic field acting from the magnet 11 to each of the magnetic sensors 12 to 15, and coincide with the magnetization direction (F direction) of the free magnetic layer 31 of each GMR element 20. ing.

As shown in FIG. 3A, the magnetization relationship (the relationship between the P direction and the F direction) between the pinned magnetic layer 29 and the free magnetic layer 31 of the GMR element 20 constituting each of the magnetic sensors 12 to 15 is all orthogonal. ing. Therefore, the electric resistance value of the GMR element 20 of each of the magnetic sensors 12 to 15 becomes the same value. Thus, the output obtained from the electrical circuit shown in FIG. 10 is zero.

Next, it is assumed that the magnet 11 slides in the Y1 direction from the reference state of FIG. The state is shown in FIG. 3 (b). At this time, the magnetization relationship (the relationship between the P direction and the F direction) between the pinned magnetic layer 29 and the free magnetic layer 31 of the GMR element 20 constituting the Y-axis magnetic sensors 12 and 14 is the same as the reference state and remains orthogonal. is there. Thus, the differential output of the X-axis magnetic sensors 12, 14 does not change from the reference state (it remains zero).

On the other hand, the magnetization direction (F direction) of the free magnetic layer of the GMR element 20 forming the X-axis magnetic sensors 13 and 15 changes from the reference state of FIG. 3A. As shown in FIG. 3B, the magnetization angle (the angle between the P direction and the F direction) of the fixed magnetic layer 29 and the free magnetic layer 31 of the GMR element 20 constituting the X-axis magnetic sensor 13 located on the left side in FIG. It becomes smaller than the orthogonal state. Therefore, the electric resistance value of the GMR element 20 constituting the X-axis magnetic sensor 13 becomes smaller than the reference state.

On the other hand, as shown in FIG. 3B, the magnetization angles (P direction and F direction of the fixed magnetic layer 29 and the free magnetic layer 31 of the GMR element 20 constituting the X-axis magnetic sensor 15 located on the right side in the figure) The angle between them is larger than that in the orthogonal state. Therefore, the electric resistance value of the GMR element 20 constituting the X-axis magnetic sensor 15 becomes larger than the reference state.

The moving position (moving distance from the reference position (origin)) of the magnet 11 in the Y1 direction can be detected by the differential output of the X-axis magnetic sensors 13 and 15 obtained by the electric circuit of FIG. Here, “differential output” refers to an output obtained by adding or subtracting the output from the X-axis magnetic sensor 13 (Y-axis magnetic sensor 12) and the output from the X-axis magnetic sensor 15 (Y-axis magnetic sensor 14) It is.

Next, it is assumed that the magnet 11 slides in the 45 ° oblique direction between the Y1 direction and the X1 direction from the reference state of FIG. 3A. The state is shown in FIG. 3 (c). Here, it is assumed that the moving amount L1 of the magnet 11 in the Y1 direction in FIG. 3 (c) is the same as the moving amount L1 in FIG. 3 (b).

When the magnet 11 slides obliquely as shown in FIG. 3C, although the amount of movement L1 in the Y1 direction is the same, the direction of the horizontal magnetic field acting on the X-axis magnetic sensors 13 and 15 changes. This will be described with reference to FIG.

FIG. 4 (a) is an enlarged plan view showing the relationship between the magnet 11 and the X-axis magnetic sensor 13 on the left side when the magnet 11 slides in an oblique direction, and FIG. 4 (b) is the X axis on the right FIG. 6 is an enlarged plan view showing the relationship between the magnetic sensor 15 and the magnet 11;

As shown in FIG. 4A, the magnet 11 approaches the X-axis magnetic sensor 13. Arrow B indicates the magnetic pole perpendicular direction of the N pole. A thick arrow F1 indicates the direction of the horizontal magnetic field flowing into the X-axis magnetic sensor 13, and coincides with the magnetization direction of the free magnetic layer 31. Further, an arrow f1 indicated by an alternate long and short dash line in FIG. 4A is a direction of a horizontal magnetic field which acts when the magnet 11 is axially moved as shown in FIG. 3B, that is, an X axis magnetic sensor shown in FIG. It coincides with the magnetization direction of the thirteenth free magnetic layer 31.

As shown in FIG. 4A, since the magnet 11 approaches the X-axis magnetic sensor 13, the X-axis magnetism is compared with the direction f1 of the horizontal magnetic field that acts when the magnet 11 in FIG. The direction F1 of the horizontal magnetic field flowing into the sensor 13 approaches the magnetic pole perpendicular direction B. Here, the direction F1 of the horizontal magnetic field is inclined by θ1 from the perpendicular direction B of the magnetic pole. The inclination θ1 is positioned on the magnetic pole perpendicular direction B side by the inclination difference θ2 as compared with the horizontal magnetic field direction f1 in FIG. 3B.

On the other hand, as shown in FIG. 4 (b), the magnet 11 is moved away from the X-axis magnetic sensor 15. Arrow C indicates the magnetic pole perpendicular direction of the N pole. A thick arrow indicates the direction F2 of the horizontal magnetic field flowing into the X-axis magnetic sensor 15, which coincides with the magnetization direction of the free magnetic layer 31. Further, an arrow f2 indicated by an alternate long and short dash line in FIG. 4B is a direction of a horizontal magnetic field which acts when the magnet 11 is axially moved as shown in FIG. 3B, that is, an X axis magnetic sensor shown in FIG. The magnetization directions of the fifteen free magnetic layers 31 coincide with each other.

As shown in FIG. 4B, since the magnet 11 is moved away from the X-axis magnetic sensor 15, the X-axis magnetic field is compared with the direction f2 of the horizontal magnetic field that acts when the magnet 11 in FIG. The direction F2 of the horizontal magnetic field flowing into the sensor 15 moves away from the magnetic pole perpendicular direction C. Here, the direction F2 of the horizontal magnetic field is inclined from the magnetic pole perpendicular direction C by θ3. The inclination θ3 is at a position farther from the magnetic pole vertical direction C by the inclination difference θ4 than the horizontal magnetic field direction f2 in FIG. 3B.

Thus, when the magnet 11 is slid obliquely as shown in FIG. 3C, when the magnet 11 is slid in the Y1 direction as shown in FIG. 3B, the X-axis magnetic sensors 13, 15 The directions (F1 and f1 and F2 and f2) of the incoming horizontal magnetic field are changed. As described above, the inclination is between the horizontal magnetic field direction F1 acting on the X-axis magnetic sensor 13 in FIG. 4A and the horizontal magnetic field direction f1 acting on the X-axis magnetic sensor 13 in FIG. Between the horizontal magnetic field direction F2 acting on the X-axis magnetic sensor 15 in FIG. 4 (b) and the horizontal magnetic field direction f2 acting on the X-axis magnetic sensor 13 in FIG. 3 (b) A slope difference θ4 occurs.

Therefore, by obtaining the differential output between the X-axis magnetic sensor 13 and the X-axis magnetic sensor 15 as in the present embodiment, the amount of change in output based on the inclination differences θ2 and θ4 described above can be reduced (preferably canceled). Therefore, the difference between the differential output of the X-axis magnetic sensors 13 and 15 for the oblique movement in FIG. 3C and the differential output of the X-axis magnetic sensors 13 and 15 for the axial movement in FIG. It can be made smaller. It is known that there is almost no difference in differential output even in the experiment described later. Therefore, as shown in FIG. 3C, even when the magnet 11 slides in an oblique direction, the magnet 11 is moved by L1 in the Y1 direction based on the differential output of the X-axis magnetic sensors 13 and 15. It is possible to detect

FIG. 5 (a) is an enlarged plan view showing the relationship between the magnet 11 and the Y-axis magnetic sensor 12 located on the upper side in the figure when the magnet 11 slides in the oblique direction as shown in FIG. 3 (c). 5 (b) is an enlarged plan view showing the relationship between the Y-axis magnetic sensor 14 and the magnet 11 located on the lower side in the drawing. In FIG. 3C, it is assumed that the magnet 11 is moved by L2 in the X1 direction.

As shown in FIG. 5A, a horizontal magnetic field component of inclination θ5 acts on the Y-axis magnetic sensor 12 from the magnetic pole vertical direction D of the S pole. The direction F3 of the horizontal magnetic field shown in FIG. 5 (a) is, for example, the direction f3 of the horizontal magnetic field acting on the Y-axis magnetic sensor 12 when the magnet 11 has moved by L1 in the X1 direction from the reference state of FIG. To the magnetic pole vertical direction D side by an inclination difference .theta.6.

On the other hand, as shown in FIG. 5B, the horizontal magnetic field component of inclination θ7 acts on the Y-axis magnetic sensor 14 from the magnetic pole vertical direction E of the S pole. The direction F4 of the horizontal magnetic field shown in FIG. 5B is, for example, the direction f4 of the horizontal magnetic field acting on the Y-axis magnetic sensor 14 when the magnet 11 has moved by L1 in the X1 direction from the reference state of FIG. It is further away from the magnetic pole perpendicular direction E by the inclination difference θ8.

Thus, when the magnet 11 is slid obliquely as shown in FIG. 3C, when the magnet 11 is slid in the X1 direction from the reference state of FIG. 3A, the Y-axis magnetic sensors 12, 14 The direction of the horizontal magnetic field flowing into the direction changes, but by obtaining the differential output between the Y-axis magnetic sensor 12 and the Y-axis magnetic sensor 14 as in this embodiment, an output based on the inclination difference θ6, θ8 described above The amount of change can be reduced (preferably offsetted). Therefore, as shown in FIG. 3C, even when the magnet 11 slides in the oblique direction, the magnet 11 is moved by L2 in the X1 direction based on the differential output of the Y-axis magnetic sensors 12 and 14. It is possible to detect

6 is a perspective view of the magnetic detection device according to the second embodiment, FIG. 7 is an enlarged side view of the magnetic detection device when viewed from the direction of the arrow in FIG. 6, and FIG. A plan view of the magnet and the magnetic sensor shown, FIG. 8 (b) is a plan view when the magnet slides in the Y1 direction from the reference state of FIG. 8 (a), and FIG. 8 (c) is FIG. In the reference state, the magnet slides in the 45 ° oblique direction between the Y1 direction and the X1 direction.

As shown in FIG. 6, the magnetic detection device 40 is configured to include a magnet 41 and magnetic sensors 42 to 45. The magnet 41 is slidably supported in the XY plane.

As shown in FIG. 6, the magnet 41 is formed in a disk shape. The upper and lower surfaces 41a and 41b of the magnet 41 shown in FIG. 6 are magnetic pole surfaces. For example, the upper surface 41a is magnetized to the N pole and the lower surface 41b is magnetized to the S pole.

As shown in FIG. 7, four magnetic sensors 42 to 45 are provided on a substrate 46. As shown in FIG. 7, the magnet 41 is supported in a slightly floating state from above the substrate 46. Specifically, the magnet 41 is supported at a distance of about 0.5 to 1.0 mm from the upper surface of the substrate 46. However, in each of the magnetic sensors 42 to 45, the magnets 41 are not disposed just beside the magnetic sensors 42 to 45, but are disposed slightly apart in the height direction so that a horizontal magnetic field can be appropriately introduced from the magnets 41. The moving area of the magnet 41 is in the area surrounded by the magnetic sensors 42 to 45. The magnet 41 and each of the magnetic sensors 42 to 45 maintain a non-contact state.

As shown in FIG. 6 and FIG. 8, the pair of X-axis magnetic sensors 43 and 45 are disposed on the X-axis line via the intersection center O with the Y-axis line. In addition, the pair of Y-axis magnetic sensors 42 and 44 are disposed on the Y-axis along the intersection center O with the X-axis. The distance between each X-axis magnetic sensor 43, 45 and each Y-axis magnetic sensor 42, 44 and the intersection center O is constant.

As shown in FIGS. 6 and 8, the magnet 41 is slidably supported in an XY plane surrounded by the X-axis magnetic sensors 43 and 45 and the Y-axis magnetic sensors 42 and 44.

FIGS. 6 and 8A show a reference state in which the center 41c of the magnet 41 is located at the intersection center O (moving origin). At this time, the orientation of the magnet 41 with respect to the magnetic sensors 42 to 45 is regulated such that the centers of the magnetic sensors 42 to 45 are opposed in the direction perpendicular to the magnetic poles of the N and S poles of the magnet 41.

Each of the magnetic sensors 42 to 45 has the same configuration including the GMR element 20 whose electric resistance value changes with respect to an external magnetic field. The configuration of the GMR element 20 is as shown in FIG.

As shown in FIG. 8A, the magnetization direction (P direction) of the pinned magnetic layer 29 of the GMR element 20 provided in the Y-axis magnetic sensor 42 on the upper side in the drawing is the X1 direction. The magnetization direction (P direction) of the pinned magnetic layer 29 of the GMR element 20 provided in the Y-axis magnetic sensor 44 on the lower side of the drawing is the X2 direction. In this embodiment, the pinned magnetic layers 29 of the GMR elements 20 provided in the Y-axis magnetic sensors 42 and 44 are in opposite directions to each other, but may be pinned in the same direction.

As shown in FIG. 8A, the magnetization direction (P direction) of the pinned magnetic layer 29 of the GMR element 20 provided in the X-axis magnetic sensor 43 on the left side in the drawing is the Y2 direction. The magnetization direction (P direction) of the pinned magnetic layer 29 of the GMR element 20 provided in the X-axis magnetic sensor 45 on the right side of the drawing is the Y1 direction. In this embodiment, the pinned magnetic layers of the GMR elements provided in the X-axis magnetic sensors 43 and 45 are in opposite directions to each other, but may be pinned in the same direction.

The Y-axis magnetic sensors 42 and 44 and the X-axis magnetic sensors 43 and 45 respectively constitute an electric circuit shown in FIG.

The thick arrows shown in FIG. 8 indicate the direction of the horizontal magnetic field acting from the magnet 41 to each of the magnetic sensors 42 to 45, and the magnetization direction of the free magnetic layer of the GMR element 20 constituting each of the magnetic sensors 42 to 45 (F direction Match the).

In the reference state of FIG. 8A, the magnetization relationship (the relationship between the P direction and the F direction) between the pinned magnetic layer 29 and the free magnetic layer 31 of the GMR elements 20 constituting each of the magnetic sensors 42 to 45 is all orthogonal. ing. Therefore, the electric resistance values of the GMR elements 20 constituting the magnetic sensors 42 to 45 become the same value. Therefore, the output obtained from the electric circuit shown in FIG. 10 is zero.

Next, it is assumed that the magnet 41 slides in the Y1 direction by a predetermined distance L1 from the reference state of FIG. 8A. FIG. 8 (b) shows the state. At this time, the magnetization relationship (the relationship between the P direction and the F direction) between the fixed magnetic layer 29 and the free magnetic layer 31 of the GMR element 20 constituting the Y-axis magnetic sensors 42 and 44 maintains the orthogonal state. Thus, the differential outputs of the Y-axis magnetic sensors 42, 44 do not change (the output remains zero).

On the other hand, the magnetization direction (F direction) of the free magnetic layer 31 of the GMR element 20 constituting the X-axis magnetic sensors 43 and 45 changes from the reference state. As shown in FIG. 8B, the magnetization direction (F direction) of the free magnetic layer 31 of the GMR element 20 constituting the X-axis magnetic sensor 43 is inclined from the center 41c of the magnet 41 with respect to the Y1-Y 2-axis direction. It is θ10. The magnetization angle (the angle between the P direction and the F direction) of the fixed magnetic layer 29 and the free magnetic layer 31 of the GMR element 20 constituting the X-axis magnetic sensor 43 is larger than that in the orthogonal state. Therefore, the electric resistance value of the GMR element 20 constituting the X-axis magnetic sensor 43 becomes larger than the reference state shown in FIG.

On the other hand, as shown in FIG. 8B, the magnetization direction (F direction) of the free magnetic layer 31 of the GMR element 20 constituting the X-axis magnetic sensor 45 is the magnet 41 with respect to the Y1-Y 2-axis direction. The inclination is θ11 from the center 41c of The magnetization angle (the angle between the P direction and the F direction) of the fixed magnetic layer 29 and the free magnetic layer 31 of the GMR element 20 constituting the X-axis magnetic sensor 45 is smaller than that in the orthogonal state. Therefore, the electric resistance value of the GMR element 20 constituting the X-axis magnetic sensor 45 becomes smaller than the reference state. Here, since the inclination θ10 and the inclination θ11 are substantially the same, the amounts of change in electrical resistance from the reference state of the X-axis magnetic sensors 43 and 45 are substantially the same.

The moving position (moving distance from the reference position) of the magnet 41 in the Y1 direction can be detected by the differential output of the X-axis magnetic sensors 43 and 45 obtained by the electric circuit of FIG.

Next, it is assumed that the magnet 41 slides in the 45 ° oblique direction between the Y1 direction and the X1 direction from the reference state of FIG. 8A. The condition is shown in FIG. 8 (c). Here, the moving amount L1 of the magnet 41 in the Y1 direction in FIG. 8C is the same as that in FIG. 8B.

When the magnet 41 slides obliquely as shown in FIG. 8C, the movement amount L1 of the magnet 41 in the Y1 direction is the same as that in FIG. 8B, but acts on the X-axis magnetic sensors 43 and 45. The direction of the horizontal magnetic field (the magnetization direction (F direction) of the free magnetic layer) is different from that in the case of axial movement in FIG. 8 (b).

As shown in FIG. 8C, the magnetization direction (F direction) of the free magnetic layer 31 of the GMR element 20 constituting the X-axis magnetic sensor 43 is θ12 from the center 41c of the magnet 41 with respect to the Y1-Y2 direction. It is inclined. Inclination (theta) 12 becomes smaller than inclination (theta) 10 when the magnet 41 in FIG.8 (b) axial-moves. Therefore, the electrical resistance value of the GMR element 20 constituting the X-axis magnetic sensor 43 is larger than that in the reference state, but smaller than that in the axial movement of FIG. 8B.

On the other hand, as shown in FIG. 8C, the magnetization direction (F direction) of the free magnetic layer 31 of the GMR element 20 constituting the X-axis magnetic sensor 45 is from the center 41c of the magnet 41 with respect to the Y1-Y2 direction. It is inclined at θ13. The inclination θ13 is larger than the inclination θ11 when the magnet 41 in FIG. 8B is axially moved. Therefore, although the electrical resistance value of the GMR element constituting the X-axis magnetic sensor 43 is smaller than that in the reference state, it is larger than in the axial movement of FIG. 8B.

Thus, when the magnet 41 is slid obliquely as shown in FIG. 8C, the magnet 41 is slid in the Y1 direction from the reference state of FIG. 8A and the X-axis magnetic sensors 43, 45. The direction (the magnetization direction of the free magnetic layer) of the horizontal magnetic field flowing into the magnetic recording medium changes as shown in FIG. 8 (c) by obtaining a differential output between the X axis magnetic sensor 43 and the X axis magnetic sensor 45 as in this embodiment. The amount of change in output based on the difference in inclination (θ10−θ12, θ11−θ13) between the oblique movement in (a) and the axial movement in FIG. 8 (b) can be reduced (preferably can be canceled). Therefore, as shown in FIG. 8C, even when the magnet 41 slides in an oblique direction, the magnet 41 moves by L1 in the Y1 direction based on the differential output of the X-axis magnetic sensors 42 and 44. It is possible to detect

The moving distance L2 of the magnet 41 in the X1 direction shown in FIG. 8C can also be detected from the differential output of the Y-axis magnetic sensors 42 and 44. As for the Y-axis magnetic sensors 42 and 44, when the magnet 41 is axially moved by L2 in the X1 direction from the reference state, the direction of the horizontal magnetic field flowing into the Y-axis magnetic sensors 42 and 44 (the magnetization direction of the free magnetic layer (F direction)) changes, but by obtaining the differential output between the Y-axis magnetic sensor 42 and the Y-axis magnetic sensor 44 as in this embodiment, the oblique movement of FIG. The amount of change in output based on the difference in inclination with the axis movement in b) can be reduced (preferably offsetable).

From the above, when the magnets 11 and 41 slide in the XY plane, the differential outputs of the X axis magnetic sensors 13, 15, 43 and 45, and the difference between the Y axis magnetic sensors 12, 14, 42 and 44 The moving position of the magnets 11 and 41 can be detected with high accuracy by the dynamic output.

In the present embodiment, as shown in FIG. 2 and FIG. 7, in order to make horizontal magnetic field components flow into each of the magnetic sensors 12-15, 42-45, each of the magnetic sensors 12 15,42-45 can be arranged. Therefore, thinning of the magnetic detection devices 10 and 40 can be realized. In particular, in the embodiment shown in FIG. 1 in which the magnetized surface is the side surface of the magnet 11, the magnet 11 can be disposed just beside each of the magnetic sensors 12 to 15 as shown in FIG. Can be realized.

Also, in order to detect the angle change of the horizontal magnetic field due to the sliding movement of the magnets 11 and 41 by the respective magnetic sensors 12 to 15 and 42 to 45, the respective magnetic sensors 12 to 15 within the entire movement range of the magnets 11 and 41 42 to 45 can be made to act as large as the free magnetic layer 31 of the GMR element 20 is magnetically saturated, and disturbance noise can be reduced and output linear characteristics can be improved as compared with the prior art.

Note that, instead of the GMR element 20, a TMR element in which the nonmagnetic layer 30 shown in FIG. 9 is formed of an insulating layer can be used.
The planar shape of the magnets 11 and 41 may be elliptical or the like, but is preferably circular.

The magnetic detection device 10 shown in FIG. 1 was manufactured. The minimum gap between the magnet 11 and each of the magnetic sensors 12 to 15 in the reference state shown in FIG. 3A was set to 2.5 mm. In addition, for the magnet 11, platinum was used. The driving voltage was 2.5 V, and the magnet 11 was slid in the Y1 direction as shown in FIG. 3 (b). Then, the movement distance of the magnet 11 and the differential outputs of the X-axis magnetic sensors 13 and 15 and the Y-axis magnetic sensors 12 and 14 were obtained. The experimental results are shown in FIG.

As shown in FIG. 11, it was found that the differential output of the X-axis magnetic sensors 13 and 15 linearly changes as the magnet 11 slides. On the other hand, it was found that the differential outputs of the Y-axis magnetic sensors 12 and 14 did not change.

Subsequently, as shown in FIG. 3C, the magnet 11 was slid in the direction of 45 degrees diagonally between the Y1 direction and the X1 direction. Then, the movement distance of the magnet 11 and the differential outputs of the X-axis magnetic sensors 13 and 15 and the Y-axis magnetic sensors 12 and 14 were obtained. The experimental results are shown in FIG.

As shown in FIG. 12, it was found that the differential output of the X-axis magnetic sensors 13 and 15 and the Y-axis magnetic sensors 12 and 14 linearly changes with the sliding movement of the magnet 11 (in FIG. 12, the X-axis The differential outputs of the magnetic sensors 13 and 15 overlap the differential outputs of the Y-axis magnetic sensors 12 and 14).

FIG. 13 shows both the relationship between the sliding movement distance of the Y1 component of the magnet 11 and the differential output of the X-axis magnetic sensors 13 and 15 obtained from the experiment of FIG. 12 in oblique movement, and the experimental results of FIG. Is a graph.

As shown in FIG. 13, it can be seen that both graphs overlap. That is, it has been found that even if the magnet 11 is slid in the oblique direction, it is possible to obtain moving distance components in the X-axis direction and the Y-axis direction with high accuracy.

Next, a magnetic detection device 40 shown in FIG. 6 was manufactured. Sintered neodymium was used for the magnet 41. The other experimental conditions were the same as in the experiments of FIGS. First, as shown in FIG. 8B, the magnet 41 was slid in the Y1 direction. Then, the movement distance of the magnet 41 and the differential outputs of the X-axis magnetic sensors 43 and 45 and the Y-axis magnetic sensors 42 and 44 were obtained. The experimental results are shown in FIG.

As shown in FIG. 14, it was found that the differential outputs of the X-axis magnetic sensors 43 and 45 change linearly as the magnet 41 slides. On the other hand, it was found that the differential outputs of the Y-axis magnetic sensors 42 and 44 did not change.

Subsequently, as shown in FIG. 8C, the magnet 41 was slid in the direction of 45 degrees diagonally between the Y1 direction and the X1 direction. Then, the movement distance of the magnet 41 and the differential outputs of the X-axis magnetic sensors 43 and 45 and the Y-axis magnetic sensors 42 and 44 were obtained. The experimental results are shown in FIG.

As shown in FIG. 15, it was found that the differential outputs of the X-axis magnetic sensors 43 and 45 and the Y-axis magnetic sensors 42 and 44 linearly change with the sliding movement of the magnet 41 (in FIG. 15, the X-axis The differential outputs of the magnetic sensors 43 and 45 overlap the differential outputs of the Y-axis magnetic sensors 12 and 14).

FIG. 16 shows both the relationship between the sliding movement distance of the Y1 component of the magnet 41 and the differential output of the X-axis magnetic sensors 43 and 45 obtained from the experiment of FIG. 15 in oblique movement, and the experimental results of FIG. Is a graph.

As shown in FIG. 16, it can be seen that both graphs overlap. That is, it has been found that even if the magnet 41 is slid in the oblique direction, it is possible to obtain moving distance components in the X-axis direction and the Y-axis direction with high accuracy.

10, 40 Magnetic Detection Device 11 Magnets 12, 14, 42, 44 Y-Axis Magnetic Sensors 13, 15, 43, 45 X-Axis Magnetic Sensors 20 GMR Elements 29 Fixed Magnetic Layer 30 Non-Magnetic Layer 31 Free Magnetic Layer 41 Magnet F Free Magnetic Magnetization direction P of the layer Magnetization direction of the pinned magnetic layer

Claims (4)

In a magnetic detection device having a magnet and a non-contact type magnetic sensor provided with a magnetoresistance effect element whose electric resistance value changes with respect to an external magnetic field,
The magnetoresistance effect element has a laminated structure of a fixed magnetic layer in which the magnetization direction is fixed, and a free magnetic layer which is formed on the fixed magnetic layer via the nonmagnetic layer and in which the magnetization direction changes with respect to the external magnetic field. It is configured to have
A pair of X-axis magnetic sensors and a pair of Y-axis magnetic sensors are disposed on orthogonal X-axis lines and Y-axis lines, respectively, via a cross center.
The magnet is slidably supported in an XY plane surrounded by the X-axis magnetic sensor and the Y-axis magnetic sensor.
When the magnet slides in the XY plane, the differential of the X-axis magnetic sensor is based on the change in electric resistance of the magnetoresistive element with the change in the angle of the horizontal magnetic field flowing into each magnetic sensor. A magnetic detection device characterized in that the position of the magnet can be detected by an output and a differential output of the Y-axis magnetic sensor. The pinned magnetic layers of the magnetoresistance effect elements constituting each X axis magnetic sensor are respectively magnetized and fixed in a direction parallel to the Y axis direction, and the pinned magnetic layers of the magnetoresistance effect elements constituting each Y axis magnetic sensor are The magnetic detection device according to claim 1, wherein the magnetization is fixed in a direction parallel to the X-axis direction. The magnetic detection device according to claim 1, wherein a side of the magnet facing each of the magnetic sensors is a magnetized surface. The magnetic detection device according to claim 1, wherein the upper and lower surfaces of the magnet are magnetized surfaces.

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