JP2001159542A - Rotation angle sensor and rotation angle sensor unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation angle sensor detecting a 360-degree absolute position, allowing easy distinction of element orientation, and allowing improve ment of a manufacturing yield by a simple manufacturing method. SOLUTION: This rotation angle sensor has substrates each provided with a magnetoresistive elements, a wiring board connecting the magnetoresistive elements to form a bridge circuit, and a sensor holder provided with the substrates and the wiring board. The sensor holder has the substrates in multiples of four, while at least one pair of the substrates is disposed on the wiring board such that the substrates are inclined by 80-100 degrees.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic field sensor, and more particularly to a rotation angle sensor or a rotation angle sensor unit for detecting the direction of an external magnetic field.

[0002]

2. Description of the Related Art A rotation angle sensor is used for detecting a rotation angle of a rotating magnetic field. A rotation angle sensor using an AMR element has an anisotropic magnetoresistance effect (AMR).
Effect), a magnetic sensor comprising a thin film of a ferromagnetic material such as NiFe or NiCo, which generally has a magnetoresistance change rate of about 3% and a small output. In order to obtain a larger output, a GMR element using a giant magnetoresistance effect (GMR effect) may be used instead of the AMR element. The GMR element is composed of a thin film in which ferromagnetic layers and non-magnetic layers having a predetermined thickness are alternately laminated, and the magnetoresistance ratio can be increased to about 70%. An extremely large magnetoresistance effect can be obtained as compared with AMR. However,
Each of the prior arts has the following problems.

[0003]

Since the output of the rotation angle sensor of the AMR element is low, it is difficult to obtain a sufficient output from a high-sensitivity rotation angle sensor. For efficient detection, it is desirable that the sensor can be used with one cycle of output. However, the rotation angle sensor of the AMR element has an external magnetic field of 36.
For the purpose of detecting an external magnetic field showing a change of 0 °, 2
Requires periodic output. A two-cycle output requires a more complicated detection signal processing circuit than a one-cycle output.

The rotation angle of a rotation angle sensor of a GMR element changes with the magnitude of a magnetic field that enters the plane of a magnetoresistive film. If the strength of the external magnetic field is constant, it is difficult to detect the rotation angle. To make up for this,
It has been studied to provide a current bias film along the GMR element. The current bias film is a conductor through which a current flows, and can apply a magnetic bias to the GMR element by a magnetic field caused by the current. Such a configuration is disclosed in Japanese Patent Application Laid-Open No. H11-194161. Also,
Japanese Patent Publication No. 11-505931 discloses that the current bias M
An R element is disclosed. However, these configurations make it difficult to apply a uniform bias magnetic field from the current bias film to the GMR element or the MR element.

As another structure, an antiferromagnetic layer bias has been studied. This is a rotation angle sensor using a GMR element in which a ferromagnetic layer whose magnetization is fixed by an antiferromagnetic layer, a nonmagnetic intermediate layer, and a magnetically free ferromagnetic layer are combined. In this configuration, a GMR element constituting a bridge circuit is provided on a single substrate by batch deposition. However, when forming a bridge circuit, it is necessary to set different bias directions, which is difficult with a manufacturing method using batch film formation. That is, when heat treatment is performed to set one bias direction, there is a problem that the other bias direction is shifted. As described above, it is difficult to sufficiently cope with the magnetization temperature and the magnetic field required for the antiferromagnetic layer.
It is not suitable for detecting the absolute position at an angle of 360 ° by sufficiently extracting the performance of the element. Therefore, the object of the present invention is 360 °
It is an object of the present invention to provide a rotation angle sensor capable of detecting the absolute position of the angle, reducing the assembly cost, and easily determining the direction of the element at the time of assembly.

[0006]

A rotation angle sensor according to the present invention includes a substrate having a magnetoresistive element, a wiring board connecting the magnetoresistive elements to form a bridge circuit, and the substrate and the wiring board. A sensor holder, wherein the substrate has a multiple of 4 on the sensor holder, and at least two of the substrates have an angle of 80 °
It is characterized by being arranged at an inclination of １００100 °. In this configuration, the direction of the magnetoresistive element is set by arranging the magnetoresistive element in which the bias direction is set in advance in a predetermined direction on the sensor holder.

Another rotation angle sensor according to the present invention includes a substrate having a magnetoresistive element, a wiring substrate on which the substrate is arranged, and a conductive member that connects the wiring substrate and the substrate to form a bridge circuit. And the substrate has a multiple of 4 on the wiring substrate, and at least two of the substrates are arranged at an angle of 80 ° to 100 ° on the surface of the wiring substrate,
A sealing member for covering the substrate and the conductive member is provided. In this configuration, the direction of the magnetoresistive element is set by arranging the substrate with the magnetoresistive element in which the bias direction is set in advance on the wiring board in a predetermined direction. In this configuration, it is preferable that electrode pins are provided on the wiring board and only the electrode pins are exposed outside the mold when the surface is covered with the mold.

In the present invention, the magnetoresistive element provided on the substrate includes a free ferromagnetic layer (free layer) having a rotatable magnetization axis when no magnetic field is applied, a nonmagnetic layer,
At least four layers of a ferromagnetic layer having a fixed magnetization axis (fixed layer) and a bias layer for fixing the magnetization axis of the fixed layer are stacked. The bias layer is an antiferromagnetic layer or a laminated ferrilayer. A magnetoresistive element is composed of a multilayer film in which at least four layers are stacked. It is desirable to use a so-called spin valve element. In any of the above aspects of the present invention, the magnetoresistive element may have a structure in which one or two elements are provided on the substrate. Here, the element or the magnetoresistive element includes a pair of electrode parts and a patterned magnetoresistive film connecting between the electrode parts. Also,
Each of the magnetoresistive elements arranged on the wiring board includes one or two elements on the board, and by arranging each at an arbitrary position on the wiring board, the shape of the magnetoresistive element is reduced in size and made the same. This improves the yield of the magnetoresistive element.

In the rotation angle sensor according to the present invention,
The first and third magneto-resistive elements are arranged at 160 to 200 degrees, the second and fourth magneto-resistive elements are arranged at 160 to 200 degrees,
The second magnetoresistive element is 80 with respect to the first magnetoresistive element.
It is possible to adopt a configuration in which the components are arranged at an angle of ° to 100 °.
Preferably, the range of the inclination angle of 80 ° to 100 ° is equivalent to 90 ° and the range of the inclination angle of 160 ° to 200 ° is equivalent to 180 °, so that the output signal of the rotation angle sensor is Can be increased in symmetry. These angles are degrees of inclination compared on the surface of the wiring board. In the present invention, the direction of the fixed layer of the second magnetoresistive element is inclined by 80 ° to 100 ° with respect to the first magnetoresistive element. In the third magnetoresistive element with respect to the element, the orientation of the fixed layer is inclined by 80 ° to 100 °,
The same effect can be obtained in the fourth magnetoresistive element having a configuration in which the orientation of the fixed layer is inclined by 80 ° to 100 ° with respect to the third magnetoresistive element.

In the present invention, a mark for discriminating the magnetization direction of the fixed layer can be added to the front or back surface of the magnetoresistive element or the substrate. Also, the directionality of the element at the time of assembly can be recognized by making the shape of the magnetoresistive element asymmetric or forming a position detection pattern on the element surface. Here, the mark is magnetically or electrically disposed apart from the magnetoresistive film,
It is desirable to provide a configuration that has a shape that can be distinguished and that is not provided with an object equivalent to the mark or an object that is difficult to distinguish from the center of the substrate. In the present invention,
When arranging the spin valve element, a processing circuit for processing an output signal of a rotation angle sensor may be provided on the sensor holder. This improves the assemblability of the processing circuit. In addition, a processing circuit can be provided on the opposite side of the surface on which the spin valve element is arranged to further reduce the size.

According to the present invention, there is provided any one of the rotation angle sensors described above, and a permanent magnet disposed as a magnetic field generating means around a sensor holder in the rotation angle sensor, wherein the permanent magnet is provided on the rotation shaft. A rotation angle sensor unit for detecting a rotation angle of a rotation shaft, wherein the rotation angle sensor unit is rotatable and applies a rotating magnetic field along a surface of a substrate to the sensor holder. The rotating magnetic field refers to a magnetic field having a uniform direction rotated with the rotation axis. It is desirable that the rotating magnetic field received by the magnetoresistive element is a uniform magnetic field (a magnetic field having substantially parallel lines of magnetic force). Further, in the rotation angle sensor unit of the present invention, a magnetic circuit is formed by providing a magnetic yoke on the permanent magnet, and a magnetic field parallel to a surface of the sensor holder is applied by the magnetic circuit, and the width of the permanent magnet is adjusted. Is preferably at least 0.8 times the circumscribed circle of the magnetoresistive element group. Here, the magnetoresistive element group is a view in which all the magnetoresistive elements are viewed as one group, and the circumscribed circle indicates a minimum virtual circle area in which the magnetoresistive element group contacts.

(Operation) The spin valve element used in the rotation angle sensor of the present invention exhibits a change in magnetoresistance of 10%, which is much larger than that of an anisotropic magnetoresistance element using a ferromagnetic thin film such as NiFe. The output increases. The principle utilizes that the angle difference between the direction of the free layer and the magnetization of the fixed layer appears as a resistance change. The change dR is as shown in equation (1). dR = k (1−cos (θ)) (1) Equations (1) Each parameter of equation (1) is (k: constant, θ: angle between free layer and fixed layer). When an appropriate external magnetic field strength is set, the angle between the free layer and the fixed layer becomes substantially equal to the angle between the external magnetic field and the fixed layer, so that a resistance change (reproduction output) according to the angle can be obtained. . At this time, in order to make the fixed layer hard to be affected by an external magnetic field, it is desirable to use an antiferromagnetic layer for fixing the orientation of the fixed layer having a large coercive force. In order to improve heat resistance, an antiferromagnetic layer having a high blocking temperature is used.

When a transparent substrate such as a glass substrate is used as the substrate on which the spin valve element is formed, the orientation of the sensor surface can be determined through the substrate. Can be arranged on the sensor holder. By setting the detection surface (electrode surface) downward as described above, it is not necessary to perform wire bonding, and the number of assembling steps can be reduced. When an opaque substrate such as a silicon substrate is used for the substrate on which the spin valve element is formed, a fixing terminal is provided on the back surface of the sensor, or a mark is provided at an appropriate position on the back surface, so that the wiring substrate can be formed. The arrangement can be facilitated.

The magneto-resistive elements having the fixed layers facing each other are electrically connected in series by a wiring prepared in advance on a wiring board, and one end of this electric circuit is connected to the power supply ( The other end is connected to the (+) side and the (-) side, and the voltage change at the middle point is used as an output. In addition, an output is similarly obtained from the other combination, and a rotation angle is obtained by comparing the two outputs.

After the magnetoresistive element or substrate is separated from the substrate on which the film is formed, it is necessary to arrange the direction of the fixed layer, that is, the direction of the substrate at an arbitrary angle in order to arrange it on the wiring substrate. For this purpose, a mark for determining the direction of magnetization of the fixed layer is added to the surface of the substrate. This mark is located at a location magnetically or electrically separated from the magnetoresistive element, has a shape that can be distinguished, and there is no object that is difficult to distinguish from the mark at a target position with respect to the center of the substrate. I do.

The mark may have any shape as long as it can be easily distinguished from the pattern of the magnetoresistive element. The shape can be a circle, a triangle, a circle, a square, or the like.
It is desirable to arrange the mark pattern at a location on the element substrate where the directionality can be easily determined. The material of the mark may be any of a spin valve film, a magnetic film, and a non-magnetic film, but it is more preferable to use a non-magnetic film. The mark may be printed with ink or the like instead of the metal film.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotation angle sensor according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view illustrating the relationship between the rotation angle sensor of the present invention and a rotating external magnetic field. FIG. 2 is a perspective view illustrating the spin valve element in FIG. FIG. 3 is a circuit diagram illustrating a bridge circuit connecting a spin valve element and a wiring board. FIG. 4 is a graph of the output waveform of the circuit of FIG. FIG. 5 is a perspective view illustrating a cross section of the configuration of the spin valve film formed on the substrate of the present invention. FIG. 6 is a graph of a magnetoresistance change characteristic of the spin valve element. FIG. 7 is a perspective view of another rotation angle sensor of the present invention. FIG. 8 is a plan view illustrating a modification of the spin valve element used in the present invention. FIG. 9 is a sectional view of the rotation angle sensor unit according to the present invention.
FIG. 10 is a sectional view of another rotation angle sensor unit according to the present invention. FIG. 11 is a perspective view of another rotation angle sensor of the present invention. FIG. 12 is a perspective view of a spin valve element used in the configuration of FIG. FIG. 13 is a circuit diagram illustrating electrical connection in the configuration of FIG. FIG. 14 is a graph of the output waveform of the circuit of FIG. FIG.
5 shows the correlation between the magnetization directions of the fixed layer of the spin valve element. FIG. 16 is a schematic diagram of another rotation angle sensor of the present invention. FIG. 17 is a perspective view of a rotation angle sensor based on the configuration of FIG.

(Embodiment 1) First, FIG. 1 is a perspective view for explaining the relationship between the rotation angle sensor of the present invention and a rotating external magnetic field. This rotation angle sensor has a configuration in which four spin valve elements 10 and a wiring board 11 for electrically connecting these spin valve elements to form a bridge circuit are provided on a sensor holder 12. Spin valve element 1
When a rotating external magnetic field was applied to 0, an output signal corresponding to the rotation angle θ of the rotating external magnetic field could be obtained from the bridge circuit. In FIG. 1, the x-axis, the y-axis, and the z-axis are virtual coordinates indicating the direction of the rotating external magnetic field and the like. The axis of the metal cylindrical sensor holder 12 is parallel to the z-axis. x-
A rotating external magnetic field substantially parallel to the y-plane was rotated about the z-axis. The angle θ between the arrow 13 indicated by the dotted line and the x-axis is the rotation angle of the rotating external magnetic field.

Next, the relationship between the arrangement of the spin valve element 10 in FIG. 1 and the rotating external magnetic field will be described. The four spin valve elements 10 are arranged parallel to the xy plane,
Adjacent objects were arranged on the wiring board so as to be inclined by 90 °. For each of the spin valve elements 10, the magnetization direction 4 of the fixed layer and the longitudinal direction thereof were set as follows. Spin valve element 10 corresponding to resistance R1
The direction of magnetization of the fixed layer was parallel to the y-axis, and the longitudinal direction of the element was parallel to the direction of the x-axis. In the spin valve element 10 corresponding to the resistance R2, the magnetization direction of the fixed layer was antiparallel to the x-axis, and the longitudinal direction of the element was parallel to the y-axis direction. In the spin valve element 10 corresponding to the resistor R3, the magnetization direction of the fixed layer was antiparallel to the y-axis, and the longitudinal direction of the element was parallel to the x-axis direction. In the spin valve element 10 corresponding to the resistor R4, the magnetization direction of the fixed layer was parallel to the x-axis, and the longitudinal direction of the element was parallel to the y-axis direction. As shown in FIG. 2, in these spin valve elements 10, a magnetoresistive pattern 2 is formed on a substrate, and electrode films for connection to a wiring substrate 11 are provided at both ends of the magnetoresistive pattern.

Next, the configuration of the wiring board 11 used in FIG. 1 will be described. The wiring board 11 is placed on a disc-shaped glass plate,
It has Cu thin film wirings 11a, 11b, 11c and 11d. These thin-film wirings include four spin valve elements 10
Are electrically connected, and some of them function as terminals to be joined to the electrode film 3 shown in FIG. 2 via solder. FIG. 3 is a conceptual circuit diagram of the bridge circuit of the spin valve element 10 connected by the wiring board 11 in this manner.
Shown in The thin film wiring 11a connecting R1 and R2 was a terminal to which a constant voltage source Vcc was applied. The thin-film wiring 11b connecting R1 and R3 was used as an output A terminal. R2 and R4
Was used as the output terminal B. R3
The thin film wiring 11d connecting R4 and R4 is connected to a ground terminal (GN
D). In FIG. 1, the intersection of the thin-film electrode 11b and the thin-film electrode 11c is laminated via an insulating film. FIG. 4 shows the output of the rotation angle sensor. When an external magnetic field applied in the horizontal direction with respect to the film surface direction of the spin valve element rotates, an output A and an output B as shown in FIG. A sinusoidal output corresponding to each rotation angle can be obtained. Since these outputs have a phase difference of π / 2 in this case, the angle of the magnetic field can be detected by performing appropriate signal processing.

Next, the step of joining the wiring substrate and the spin valve element will be described. First, solder was applied to a portion corresponding to a terminal on a wiring board. Each spin-valve element was placed on a wiring board so that the soldered electrode film was fitted to the solder. In this step, the directional marks could be recognized through the transparent glass plate. The direction of the spin valve element was positioned on the wiring board according to the direction mark. Subsequently, the structure was heat-treated in a reflow oven and then cooled naturally. The solder melted by the heat treatment was integrated, solidified during natural cooling, and the terminal of the thin film wiring and the electrode film could be joined. With respect to this wiring board, the surface on which the thin film wiring was not attached was fixed to a sensor holder via an adhesive having good heat resistance, and a rotation angle sensor was produced. Since the wiring board is attached to the sensor holder at one time, the number of assembly steps can be reduced compared to the conventional technology.

Referring to FIG. 2, the structure of the spin valve element 10 mounted on the rotation angle sensor of FIG. 1 will be described. In this spin valve element, a magnetoresistive pattern 2, electrode films 3 connected to both ends thereof, and a directional mark 5 indicating the direction of the magnetoresistive pattern 2 are formed on a substrate 1 made of a flat plate of glass or silicon. Formed. The arrow in FIG.
In the magnetoresistive pattern 2, the magnetization direction 4 of the fixed layer
It shows. The magnetoresistive pattern 2 is a patterned magnetoresistive effect film, and the laminated structure thereof will be described with reference to FIG. This figure corresponds to a partial cross-sectional view of the magnetoresistive pattern of FIG. The film configuration of the magnetoresistive pattern itself is a known configuration, and a multilayer film is formed on the substrate 1 and is patterned into one stripe. This multilayer film is a spin-valve element, and includes a free layer 10a, which is a ferromagnetic film rotatable with respect to an external magnetic field, a nonmagnetic layer 10b, which serves as a spacer, and a fixed ferromagnetic film, whose magnetization is not moved by an external magnetic field. Layer 10c
And an antiferromagnetic layer 10 for fixing the magnetization direction of the fixed layer.
d and a CAP layer 10e for protecting the antiferromagnetic layer. The antiferromagnetic layer 10d was magnetized in a certain direction through a heat treatment step in a vacuum magnetic field. Each spin valve element was provided with a thin film in the shape of a circle as a directional mark 5 so that the orientation of the fixed layer could be determined even after the substrate was cut out. FIG. 6 shows the magnetic characteristics of this spin valve element. In the figure, the horizontal axis represents the magnetic field applied to the spin valve element from the outside, and the vertical axis represents the magnetoresistance change rate. These spin-valve elements used were wafers in which a large number of sets of a spin-valve film, an electrode film 3 and a directional mark 5 were formed by batch deposition and cut into individual spin-valve elements with a dicing saw.
The specifications of these spin valve elements are the same.

(Embodiment 2) FIG. 7 shows a rotation angle sensor according to another embodiment. This figure is a configuration in which the arrangement of the spin valve element 10 and the wiring shape on the thin film substrate 11e are changed in the configuration of FIG. 1, and the electrical bridge circuit has the same configuration as that of FIG. Four spin valve elements 10
Were arranged so as to form a cross shape. In accordance with this arrangement, the thin film wirings 11a, 11b,
11c and 11d are provided. By changing the shape of the wiring board 11 as in this embodiment, the layout of the spin valve element can be easily changed.

FIG. 8 illustrates another shape of the magnetoresistive pattern. The magnetoresistive pattern and the directional mark are formed of a thin film and can have a desired shape. (A) shows a configuration in which a magnetoresistive pattern 2 and a directional mark 5 are provided between a pair of electrode films. The magnetization direction of the fixed layer in the spin valve element was directed to the side where the direction mark 5 was provided. In the figure, (b)
(C) is an embodiment in which the arrangement of the direction marks is changed.
(D) is a modified example in which the shape of the directional mark in (a) or the like is square, triangular, or star. Any of these modifications can be selected. If the shape (pattern) is easy to determine, the character pattern 5e may be used as shown in FIG. Further, a notch or the like may be provided on the substrate as a directional mark instead of the thin film pattern. Further, as shown in (f) and (g), the direction of the spin valve element may be recognized by making the shape of the spin valve element asymmetric between the electrode films. (H)
This is an example in which the shape of the electrode film is asymmetric and the direction is recognized, and one electrode film 3h has a round pattern.

FIG. 9A is a cross-sectional view of a rotation angle sensor unit using the rotation angle sensor of FIG. 7, in which a rotation angle sensor is arranged in a magnetic circuit provided on a rotation shaft.
The rotation angle of the rotating shaft is detected. That is, this rotation angle sensor unit is
The rotation angle sensor including
The yoke 14 having b and the rotating shaft 15 are on the movable side, and the fixed side and the movable mold are connected by a bearing 16. FIG.
(B) shows the yoke 14 and the permanent magnet 14 viewed from the z-axis side.
It is sectional drawing which shows the positional relationship of b. Each configuration will be described in order. First, the spin valve element 10 and a signal processing circuit (not shown) were mounted on the sensor holder 12, and a wiring board having these electrical wirings was provided. The sensor holder 12 is used for electrical connection between the wiring board and the outside.
The flat cable 17 buried in the side surface of was used. A yoke 14 including a pair of permanent magnets 14b is provided at the tip of the rotating shaft 15. A substantially parallel magnetic field H19 was formed between the opposed permanent magnets 14b. In the figure, the image of the magnetic field H19 is indicated by a dotted arrow. Further, a bearing 16 for supporting the sensor holder 12 on the inner periphery is provided at the tip of the yoke 14. Permanent magnet 14b
Is a rectangular parallelepiped, and is attached to the yoke 14 such that each of the opposing surfaces has a different pole. When the rotation axis was rotated around the z-axis, the magnetic field H19 incident parallel to the surface of the spin valve element 10 was also rotated, and the output of the rotation angle sensor changed according to the rotation angle θ. In this way, it is possible to detect the absolute position over a rotation angle of the rotation shaft of 360 °. The magnetic field H19 received by the spin valve element is desirably 50 to 100 (Oe).

FIG. 10 is a sectional view of another rotation angle sensor unit according to the present invention. This configuration is a modification of the configuration on the rotating side in FIG. It differs from the configuration in FIG. 9 in that the permanent magnet 14c is arranged at the center of the yoke and that a frame for separately holding the yoke and the bearing is provided. That is, the rotation angle sensor unit shown in FIG.
Was provided on the rotating shaft 15. A sensor holder 12 for a rotation angle sensor was provided on the inner periphery of the bearing. At this time, the sensor holder was inserted so that the spin valve element 10 was arranged between the tips of the yoke 14. FIG. 10B shows a state in which the yoke 14 including one permanent magnet 14c is fitted in a cylindrical case 15b. (B) is a view of the cylindrical case 15b in a direction along the z-axis. The cylindrical case 15b has a pair of grooves on its inner periphery. After fitting the yoke 14 in this groove and fixing it, the cylindrical case 15b
The flange of the rotating shaft was joined to the. By doing so, the magnetic field H generated from the yoke 14 together with the rotating shaft 15 was rotated. A substantially parallel magnetic field H19 was formed between the opposed permanent magnets 14c. In FIG.
The 19 images were indicated by dotted arrows. Permanent magnet 14c
The magnetic field generated by the magnetic field transmitted through the yoke 14 was applied to the spin valve element 10. When the rotating shaft 15 was rotated around the z-axis, the magnetic field H19 incident parallel to the surface of the spin valve element 10 was also rotated, and the output of the rotation angle sensor changed according to the rotation angle θ.

In the rotation angle sensor of the above-described embodiment, the sensor holder side does not necessarily need to be a fixed portion, and the rotation shaft side may be fixed and the sensor holder side may rotate. The rotation angle sensor according to the present invention detects a relative displacement. Further, the arrangement and shape of the permanent magnet are not limited to the configuration in the above embodiment. It suffices if a magnetic path is formed by a combination of the magnet and the yoke, and a desired parallel magnetic field can be applied to the rotation angle sensor.

(Embodiment 3) FIG. 11 is a perspective view of another rotation angle sensor of the present invention. This configuration is a rotation angle sensor in which a full bridge circuit is formed using a spin valve element having two spin valve films. By changing the circuit arrangement of the thin film wiring provided on the wiring board as compared with the first embodiment, it is possible to double the output signal without increasing the number of boards. The schematic configuration of the rotation angle sensor is a configuration in which a wiring board 11f is provided on a sensor holder 12 and four spin valve elements 20 that form a full bridge circuit by being connected to a thin film wiring formed on the wiring board. In the figure, the detailed configuration of the thin film wiring on the wiring board is omitted.

FIG. 12 is a perspective view of the spin valve element 20 used in FIG. This spin valve element 20
On a substrate 1 made of a flat plate of glass or silicon,
The two magnetoresistive patterns 2a and 2b, the electrode films 3a and 3b connected to both ends thereof, and the directional mark 5 indicating the direction of the magnetoresistive pattern were formed as thin films. For convenience, the magnetoresistive pattern 2a is referred to as a resistor R (N), and the magnetoresistive pattern 2b is referred to as a resistor R (N + 4). As shown in FIG. 12, the spin valve element 20 having the resistors R1 and R5
Its longitudinal direction is parallel to the x-axis, and the direction of magnetization 4 of the fixed layer is
Was parallel to the y-axis. In the spin valve element having the resistors R2 and R6, the longitudinal direction was parallel to the y-axis, and the magnetization direction 4 of the fixed layer was antiparallel to the x-axis. In the spin valve element having the resistors R3 and R7, the longitudinal direction was parallel to the x-axis, and the magnetization direction 4 of the fixed layer was antiparallel to the y-axis. In the spin valve element having the resistors R4 and R8, the longitudinal direction was parallel to the y-axis, and the magnetization direction 4 of the fixed layer was parallel to the x-axis. In addition, the laminated structure of the spin valve element forming the magnetoresistive pattern, the magnetization direction 4 of the fixed layer,
The direction marks and the like were the same as in Example 1.

FIG. 13 is a conceptual circuit diagram of the bridge circuit of the spin valve element shown in FIG. The spin valve film formed on one substrate constitutes a separate bridge circuit. One bridge circuit connects R2 and R8 to provide a terminal to which a constant voltage source Vcc is applied, connects R4 and R6 to provide a ground terminal, connects R2 and R4 to provide a terminal for output B, and connects R6 and R8 to a terminal for output B. Connected to output B 'terminal.
The other bridge corridor connects R1 and R7 to serve as a terminal for applying a constant voltage source Vcc, connects R3 and R5 to serve as a ground terminal, connects R1 and R3 to serve as an output A terminal,
5 and R7 were connected to form an output A 'terminal.

This rotation angle sensor performs circuit processing on the signal output between the terminals AA ′ and the signal output between the terminals BB ′ to output an output signal having an amplitude twice as large as that of the first embodiment. I got it. The waveform of this output signal is shown in FIG.
Shown in In this way, it is possible to perform stable angle detection with a large output. In addition, the same effect can be obtained by arranging the substrate 1 regardless of the magnetization direction 4 of the fixed layer of the four spin valve elements shown in FIGS. 15 (a) to 15 (d).

FIG. 16 illustrates another embodiment of the rotation angle sensor. This rotation angle sensor is a wiring board 31
A bridge circuit was formed by providing a substrate 1 of four spin valve elements and a plurality of thin film wirings 32 and 33 by bonding, and connecting the substrate 1 and the thin film wiring by wire bonding. Here, the substrates and their arrangement were the same as in the configuration of FIG. As the connection, a thin gold wire was used. Although the total number of thin film wirings is eight, R2 and R1
By sharing the thin film wiring of R3 and R4 and R4, it is possible to reduce the number of thin film wirings to six.

Next, FIG. 17 shows an appearance in which the structure of FIG. 16 is molded with a sealing material. After the molding, the distal ends of the thin film wirings 32 and 33 are exposed from the sealing member 35, and the other members are sealed in the sealing member 35. This appearance resembled an IC chip. As the sealing member 35, an insulating resin was used. Note that FIG.
In the above, the wiring board and the thin film wiring are used, but other embodiments can be made by using a lead frame instead. Specifically, four substrates 1 are arranged on a lead frame, and the substrate and the electrode pins of the lead frame are connected via a connection 34 and then molded with a sealing member. The rotation angle sensor shown in FIG. 17 is versatile and can be mounted on a printed circuit board provided with desired wiring. For example, a printed circuit board was connected to a sensor holder, and the configuration shown in FIG. 17 could be provided on the printed circuit board.

[0034]

As described above, by using the rotation angle sensor of the present invention, it is possible to detect an absolute position for a rotation angle of 0 to 360 °. Further, by using a single-shaped spin valve element and disposing it as in the present invention, the yield can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a rotation angle sensor according to the present invention.

FIG. 2 is a perspective view of a spin valve element used in the present invention.

FIG. 3 is a circuit diagram illustrating connection in the configuration of FIG. 1;

FIG. 4 is a graph illustrating an output waveform of the circuit of FIG. 3;

FIG. 5 is a perspective view illustrating a film configuration of a spin valve element of the present invention.

FIG. 6 is a graph illustrating a magnetoresistance change characteristic of a spin valve element.

FIG. 7 is a perspective view of another rotation angle sensor of the present invention.

FIG. 8 is a plan view illustrating a modification of the spin valve element used in the present invention.

FIG. 9 is a sectional view of a rotation angle sensor unit according to the present invention.

FIG. 10 is a sectional view of another rotation angle sensor unit according to the present invention.

FIG. 11 is a perspective view of another rotation angle sensor of the present invention.

FIG. 12 is a perspective view of a spin valve element used in the configuration of FIG. 11;

FIG. 13 is a circuit diagram illustrating connection in the configuration of FIG. 11;

FIG. 14 is a graph illustrating an output waveform of the circuit in FIG. 11;

FIG. 15 is a schematic diagram showing a correlation between the magnetization directions of the fixed layer of the spin valve element.

FIG. 16 is a schematic diagram illustrating the inside of another rotation angle sensor according to the present invention.

17 is a perspective view of a rotation angle sensor based on the configuration of FIG.

[Description of Signs] 1 substrate, 2 magnetoresistive pattern, 2a 2b magnetoresistive pattern, 3a 3b electrode film, 3 electrode film, 3h
Electrode film, 4 magnetization direction of pinned layer, 5 direction mark, 5
e Character pattern, 10 Spin valve element, 10a
Free layer, 10b Non-magnetic layer, 10c Fixed layer, 10d
Antiferromagnetic layer, 10e CAP layer, 11 wiring board, 11
a 11b 11c 11d Thin film wiring, 11f wiring board, 12 sensor holder, 13 Arrow showing angle θ, 14 yoke, 14b permanent magnet, 14c permanent magnet, 15 rotation axis, 15b case, 16 bearing, 17 flat cable, 19 magnetic field H , 20 spin valve element, 31 wiring board, 32 33 thin film wiring, 34 connection, 35 sealing member

Continued on the front page F-term (reference) 2F063 AA35 BB03 BD16 CA34 DA05 DD05 EA03 GA55 LA01 LA02 2F077 AA30 AA49 CC02 JJ10 JJ23 JJ24 TT16 TT51 VV02 VV10 VV11 VV30 VV31 2G017 AA03 AC06 AC09 AD55 AD63 AD09 BA09

Claims (11)

[Claims] A substrate having a magneto-resistive element, a wiring board connecting the magneto-resistive elements to form a bridge circuit, and a sensor holder having the substrate and the wiring board; A rotation angle sensor having a multiple of four substrates and at least two of said substrates being arranged at an angle of 80 ° to 100 ° on a wiring board surface. A substrate having a magnetoresistive element, a wiring substrate on which the substrate is arranged, and a conductive member that connects the wiring substrate and the substrate to form a bridge circuit; The substrate has a multiple of 4 and at least two of the substrates are 80 ° to 100 ° on the surface of the wiring substrate.
A rotation angle sensor provided with a sealing member that is disposed at an angle and covers the substrate and the conductive member. 3. A magnetoresistive element provided on the substrate, wherein when a magnetic field is not applied, a free ferromagnetic layer (free layer) having a rotatable magnetization axis, a non-magnetic layer, and a strong magnetic axis having a fixed magnetization axis. 3. The rotation angle sensor according to claim 1, wherein at least four layers of a magnetic layer (fixed layer) and a bias layer for fixing a magnetization axis of the fixed layer are stacked. 4. The rotation angle sensor according to claim 3, wherein the magnetoresistive element has one or two elements on the substrate. 5. The magnetoresistive element according to claim 1, wherein the first magnetoresistive element and the third magnetoresistive element are 160
The second and fourth magnetoresistive elements are disposed at an angle of 160 to 200 °, and the second magnetoresistive element is disposed at an angle of 80 ° to the first magnetoresistive element. 1
The rotation angle sensor according to any one of claims 1 to 4, wherein the rotation angle sensor is disposed at an angle of 00 °. 6. The magnetoresistive element, wherein the direction of the fixed layer of the second magnetoresistive element is inclined by 80 ° to 100 ° with respect to the first magnetoresistive element, and On the other hand, in the third magnetoresistive element, the direction of the fixed layer is inclined by 80 ° to 100 °, and in the fourth magnetoresistive element, the direction of the fixed layer is 8 ° with respect to the third magnetoresistive element.
The rotation angle sensor according to claim 1, wherein the rotation angle sensor is inclined by 0 ° to 100 °. 7. The rotation angle sensor according to claim 1, wherein a mark for determining the direction of magnetization of the fixed layer is added to a surface of the magnetoresistive element or the substrate. . 8. The mark is magnetically or electrically separated from the magnetoresistive element, has a shape that can be distinguished, and has no equivalent to the mark at a target position with respect to the center of the substrate. The rotation angle sensor according to claim 7, wherein: 9. The rotation angle sensor according to claim 1, wherein a processing circuit for processing an output signal of the rotation angle sensor is provided on the sensor holder. 10. A rotation angle sensor unit for detecting a rotation angle of a rotation shaft, comprising: a rotation angle sensor according to claim 1, and a sensor holder in the rotation angle sensor. A permanent magnet arranged as a magnetic field generating means, wherein the permanent magnet is provided on the rotating shaft and is rotatable, and applies a rotating magnetic field along the surface of the substrate to the sensor holder. Rotation angle sensor unit. 11. A magnetic circuit is formed by providing a magnetic yoke on the permanent magnet, and a magnetic field parallel to a surface of the sensor holder is applied by the magnetic circuit. 0.8 of the circumcircle of
The rotation angle sensor unit according to claim 10, wherein the rotation angle is at least twice.