JPH09269205A - Magnetic rotation sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic rotation sensor capable of reducing the dimension of a rotor in the axial direction, in a magnetic rotation sensor. SOLUTION: A magnet 13 is fixed to the outer peripheral part of a rotor 12, and a cylindrical flexible base board 14, in which GMR (giant magnetic resistor) element 16 is filmed, is arranged on the periphery of the rotor 12. The GMR element 16 has nature for reducing a resistance value when a magnetic field is acted, and is formed into a pattern in which the width in the axial direction is changed in accordance with a peripheral directional position. Consequently, when the rotor 12 is rotated, the area of a region, in which magnetic field due to a magnet 13 is acted on the GMR element 16, is changed in accordance with the rotation angle of the rotor 12. Resultantly, the resistance value of the GMR element 16 is changed in accordance with the rotation angle of the rotor 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic rotation sensor, and more particularly to a magnetic rotation sensor using a magnetoresistive element.

[0002]

2. Description of the Related Art A vehicle is equipped with a rotation sensor for detecting the opening of a throttle valve and the stroke of a brake pedal. In order to improve the durability of the rotation sensor, it is desirable that the rotation angle can be detected without contact. As such a non-contact type rotation sensor, conventionally, a magnet is mounted on a rotating body, and a magnetic sensor for detecting a rotation angle of the rotating body by detecting a change in a magnetic field due to rotation of the rotating body by a magnetic detection element. Rotation sensors are known. For example, the magnetic rotation sensor disclosed in Japanese Patent Laid-Open No. 2-298815 includes a magnet that rotates together with the rotation of a rotating body such as a throttle valve, and a magnetic resistance element. The magnetoresistive element is arranged to face the magnet in the axial direction of the rotating body. When the magnet rotates with the rotating body, the magnetic field acting on the magnetoresistive element changes according to the rotation angle of the rotating body. The magnetoresistive element has a property that the resistance changes according to the magnitude of the magnetic field that acts. Therefore, in the above-described conventional magnetic rotation sensor, the resistance of the magnetoresistive element changes according to the rotation angle of the rotating body, and the rotation angle of the rotating body is detected by measuring the resistance value of the magnetoresistive element. ing.

[0003]

As described above, the conventional magnetic rotation sensor has a structure in which the rotating body and the magnetoresistive element face each other in the axial direction of the rotating body. Therefore, it is necessary to secure a space for installing the magnetoresistive element at a position in the axial direction with respect to the rotating body, so that the axial size of the magnetic rotation sensor cannot be sufficiently reduced. In this regard,
The above-mentioned conventional magnetic rotation sensor is not an optimum configuration for downsizing the sensor.

The present invention has been made in view of the above points, and an object of the present invention is to provide a magnetic rotation sensor capable of reducing the dimension in the axial direction.

[0005]

The above object is achieved by the present invention.
In a magnetic rotation sensor including a magnet that rotates together with the rotation of a rotating body, and a magnetoresistive element that changes in resistance value when a magnetic field generated by the magnet acts, This is achieved by a magnetic rotation sensor provided so as to face the magnet while being spaced apart from the rotating body in the radial direction.

According to the first aspect of the invention, the magnetoresistive element faces the magnet at a distance from the rotor in the radial direction. Therefore, it is not necessary to dispose the magnetoresistive element in the axial direction of the rotating body. This reduces the axial dimension of the magnetic rotation sensor.

Further, as described in claim 2, the above-mentioned object is, in the magnetic rotation sensor according to claim 1, the area of a region where the magnetic field generated by the magnet acts on the magnetoresistive element is the rotation. This is also achieved by a magnetic rotation sensor formed so as to change depending on the rotation angle from the reference position of the body.

According to the second aspect of the invention, the area of the region of the magnetoresistive element on which the magnetic field of the magnet acts changes in accordance with the rotation angle of the rotating body from the reference position. The resistance value changes in the region where the magnetic field of the magnetoresistive element acts. Therefore, the amount of change in the resistance value of the magnetoresistive element increases as the area in which the magnetic field acts on the magnetoresistive element increases. Therefore, the resistance value of the magnetoresistive element changes according to the rotation angle of the rotating body.

Further, as described in claim 3, the above-mentioned object is, in the invention according to claim 2, in which the width of the magnetoresistive element in the direction parallel to the axis of the rotating body is the circumferential direction of the rotating body. This can also be achieved by a magnetic rotation sensor formed in a strip shape that changes depending on the position of.

According to the third aspect of the present invention, the magnetoresistive element is formed in a strip shape such that the width in the direction parallel to the axis of the rotating body changes according to the circumferential position of the rotating body. Therefore, the area of the region where the magnetic field of the magnet acts on the magnetoresistive element changes according to the rotational position of the rotating body. Therefore, the resistance value of the magnetoresistive element changes according to the rotation angle of the rotating body.

Further, as described in claim 4, the above-mentioned object is, in the invention of claim 2, that the area density of the magnetoresistive element is changed in accordance with the circumferential position of the rotating body. It is also achieved by a magnetic rotation sensor provided. In the invention according to claim 4, the magnetoresistive element is provided so that the areal density changes according to the circumferential position of the rotating body. As the areal density of the magnetoresistive element increases, the area of the region where the magnetic field of the magnet acts on the magnetoresistive element increases. Therefore, the area of the region where the magnetic field of the magnet acts on the magnetoresistive element changes according to the rotational position of the rotating body. Therefore, the resistance value of the magnetoresistive element changes according to the rotation angle of the rotating body.

Further, as described in claim 5, the above-mentioned object is, in the invention according to claim 1, in which at least two of the magnetoresistive elements have a magnetic field applied by the magnets,
It is also achieved by a magnetic rotation sensor which is provided so as to be maximum at different rotation positions of the rotating body.

In a fifth aspect of the present invention, at least two magnetoresistive elements are provided so that the magnetic fields applied by the magnets become maximum at different rotational positions of the rotating body. Therefore, when the rotating body makes one revolution, the resistance value of the at least two magnetoresistive elements changes a number of times according to the number of the magnetoresistive elements.

[0014]

1 is a block diagram of a magnetic type rotation sensor 10 according to a first embodiment of the present invention. In FIG.
The structure when the magnetic rotation sensor 10 is viewed from the axial direction is shown. In FIG. 1, the rotor 12 is connected to a rotating body that rotates within a predetermined angle range, such as a throttle shaft, and rotates in synchronization with the rotation of the rotating body. A magnet 13 is fixed to the outer peripheral portion of the rotor 12. The magnet 13 is polarized in the axial direction of the rotor 12. A cylindrical flexible substrate 14 is arranged coaxially with the rotor 12 around the rotor 12. The flexible substrate 14 is made of a resin such as polyimide and has flexibility. Flexible substrate 14
Is a giant magnetoresistive element (hereinafter referred to as GMR element) 16
Is formed into a thin film.

FIG. 2 shows a state in which the flexible substrate 14 is extended in a plane. As shown in FIG. 2, the flexible substrate 14 is a strip-shaped substrate. As described above, since the flexible substrate 14 has flexibility, the planar flexible substrate 14 can be arranged in a cylindrical shape as shown in FIG. The horizontal direction in FIG. 2 corresponds to the circumferential direction in FIG. 1, and the vertical direction in FIG. 2 corresponds to the axial direction in FIG.

As shown in FIG. 2, the GMR element 16 extends in the left-right direction in FIG. 2 of the flexible substrate 14 and is formed such that the width in the up-down direction in the figure becomes narrower from the left side in the figure to the right side. . Electrodes 18 and 20 are formed on both sides of the flexible substrate 14. The electrodes 18 and 20 are respectively connected to the left end and the right end of the GMR element 16 in FIG.

Next, the magnetic characteristics of the GMR element 16 will be described. FIG. 3 shows the relationship between the magnetic field H in the direction parallel to the film acting on the GMR element 16 and the resistance value per unit area of the GMR element 16. As shown in FIG. 3, the GMR element 1
In No. 6, the resistance value decreases as the magnetic field H acting parallel to the film increases, and when the magnetic field H becomes equal to or higher than the saturation magnetic field Hs,
It has the property that the resistance value becomes the saturation resistance value Rs. As can be seen from FIG. 3, the resistance of the GMR element 16 depends only on the magnitude of the magnetic field H and not on the direction of the magnetic field H.

As will be described later, the GMR element 16 is formed of an artificial lattice film in which ferromagnetic layers and nonmagnetic layers are alternately formed. As a result, the magnetoresistive characteristic of the GMR element 16 is significantly improved as compared with the ordinary magnetoresistive element using the magnetoresistive effect of the semiconductor or the ferromagnetic material used in the conventional magnetic rotation sensor. . For example, the ratio (hereinafter referred to as resistance change rate) between the resistance value R0 and the saturation resistance value Rs of the GMR element 16 in a state where the magnetic field does not act is 10 times or more that of the conventional magnetoresistive element. Has become.

According to the configuration of the magnetic type rotation sensor 10 described above, the magnet 13 generates a magnetic field in a direction parallel to the axis of the rotor 12, and the magnet 13 of the flexible substrate 14 has a magnetic field as shown by a broken line in FIG. This magnetic field is applied to the opposing area A. Therefore, in the region B (indicated by hatching in FIG. 2) in the region A of the GMR element 16, the magnetic field acts in parallel to the film of the GMR element and in the vertical direction in FIG. In this case, the circumferential widths of the regions A and B are constant because they are determined by the circumferential width of the magnet 13. On the other hand, since the width of the GMR element 16 in the axial direction is changed according to the position in the circumferential direction, the width of the region B in the axial direction changes according to the position in the circumferential direction. Therefore, according to the rotation of the rotor 12, the magnet 13
When the regions A and B on which the magnetic field acts due to move, the area of the region B on which the magnetic field acts on the GMR element 16 changes accordingly. As described above, the resistance value of the GMR element 16 decreases due to the magnetic field acting parallel to the film of the GMR element 16. Therefore, as the area of the region where the magnetic field acts on the GMR element 16 increases, the GMR element 1
The overall electrical resistance of 6, ie the resistance between the electrodes 18, 20 is reduced. Therefore, the electric resistance between the electrodes 18 and 20 changes according to the rotational position of the rotor 12. In the pattern of the GMR element 16 shown in FIG. 1, the width of the GMR element 16 is reduced toward the right side of the drawing.
As the rotor 12 rotates in the clockwise direction in FIG. 1, the resistance value of the GMR element 16 increases.

For example, as shown in FIGS. 1 and 2, the magnet 1
The center of 3 is located at a distance x from the left end in FIG. 2, that is, in FIG.
The area of the region B where the magnetic field of the magnet 13 acts on the GMR element 16 at the position of the rotation angle θ shown in
(X), the total area of the GMR element 16 is S, the GMR element 16 is
R _{1 is} the resistance between the electrodes 18 and 20 in the state where no magnetic field is applied to the GMR, and the GMR is caused by the magnetic field applied by the magnet 13.
If the rate of resistance change of the element 16 is α, the electrodes 18, 20
The electrical resistance R between is R = R ₁ · (S−F (x)) / S + R ₁ · α · F (x) / S = R ₁ + R ₁ · (α-1) · F (x) / S It is calculated by (1). As can be seen from equation (1), F
GM so that (x) changes linearly with changes in x
By forming the R element 16, the resistance value R is changed to the rotor 1
It can be changed linearly with respect to the rotation angle θ of 2. The measurement range of the rotation angle of the rotor 12 is determined by the existing angle (angle ψ shown in FIG. 1) of the GMR element 16 in the circumferential direction. Therefore, by adjusting the length of the GMR element 16 in the left-right direction in FIG. 2 and appropriately providing the angle ψ, the required measurement range can be obtained.

FIG. 4 shows an example of a circuit for converting the resistance value R between the electrodes 18 and 20 into a voltage signal. As shown in FIG. 4, when a constant current I is passed between the electrodes 18 and 20 by the constant current source 30, a voltage R · I is generated between the electrodes 18 and 20. Therefore, by measuring the voltage V between the electrodes 18 and 20 with the voltmeter 32, the output signal V according to the resistance R between the electrodes 18 and 20 is obtained.

FIG. 5 shows the rotation angle of the rotor 12 and the output signal V
An example of the relationship with is shown. As described above, since the GMR element 16 is formed so that F (x) changes linearly with respect to the change of x, the GMR element 16 linearly changes with respect to the rotation angle θ of the rotor 12, as shown in FIG. A varying output signal V is obtained. The rotational position of the rotor 12 can be detected from the output signal V, and thus the rotational position of the rotating body connected to the rotor 12 can be detected.

As described above, in the magnetic rotation sensor 10 of this embodiment, the magnet 13 fixed to the rotor 12 and
The GMR element 16 faces the radial direction of the magnetic rotation sensor 10. Therefore, it is not necessary to dispose the GMR element 16 in the axial direction with respect to the rotor 12, and this makes it possible to reduce the axial dimension of the magnetic rotation sensor 10. Further, as described above, the GMR element 16 has a large resistance change rate as compared with the conventional magnetoresistive element. Therefore, the magnitude of the magnetic field and the area of the GMR element 16 required to obtain an output signal of a required magnitude are reduced. As a result, the width of the flexible substrate 14 in the axial direction can be reduced, and the magnet 13 can be downsized. As a result, the axial size of the magnetic rotation sensor 10 can be further reduced.

Further, since the GMR element 16 has a large rate of resistance change, it is possible to obtain a sufficiently large output signal only by using the constant current source 30 and the voltmeter 32, as shown in FIG. it can. Therefore, it is not necessary to amplify the output signal using an amplifier circuit or the like. As described above, according to the magnetic rotation sensor 10 of the present embodiment, the signal processing circuit can be simplified.

In the above embodiment, the magnet 13
Are arranged so that the polarization direction thereof is the axial direction of the rotor 12, but the present invention is not limited to this, and the magnet 13 is arranged so that the polarization direction thereof is the radial direction of the rotor 12. You may arrange. In this case, the GMR element 16
A magnetic field in the direction parallel to the film and in the circumferential direction acts on the film. As described above, as long as the magnetic field acts parallel to the film of the GMR element 16, the rate of change in resistance of the GMR element 16 does not depend on the direction of the magnetic field. Therefore, even if the magnet 13 is polarized in the radial direction as described above, the same effect as that of the above embodiment can be obtained.

As described above, the structure in which the magnet 13 and the GMR element 16 are opposed to each other in the radial direction of the rotor 12 is possible by forming the GMR element 16 on the surface of the flexible substrate 14 which can be curved in a cylindrical shape. Has been done. Hereinafter, a method of forming the GMR element 16 on the flexible substrate 14 will be described with reference to FIG.

FIG. 6 shows a procedure for forming the GMR element 16. First, in step 200, the flexible substrate 14
After being cleaned by ultrasonic cleaning or the like, the flexible substrate 14 is placed in the vacuum chamber of the sputtering apparatus and is cleaned by sputter cleaning in step 202. Next, in step 204, a buffer layer of NiFe or the like having a thickness of about 5 nm is formed by sputtering on the flexible substrate 14, and then in step 206, a magnetic artificial lattice layer is formed. The magnetic artificial lattice layer is
10 to 30 alternating Co layers having a thickness of about 1 nm which are ferromagnetic layers and Cu layers having a thickness of about 1 to 2 nm which are non-magnetic materials
The layers are formed by forming a film by sputtering. As a combination of materials of the ferromagnetic layer / nonmagnetic layer of the artificial lattice layer, in addition to Co / Cu described above, Co
Fe / Cu, NiFeCo / Cu, NiFe / Cu / C
A combination of o / Cu, Co / Ag and the like can be used.

After the artificial lattice layer is formed in step 206, SiN is formed on the artificial lattice layer in step 208.
A protective film made of x, SiO 2 or the like is formed. Next, step 21
At 0, the artificial lattice layer is patterned, for example, in the pattern as shown in FIG. This patterning consists of applying a resist to the artificial lattice layer and exposing it with the required pattern.
After development, it is performed by etching the artificial lattice layer. Therefore, the artificial lattice film can be easily patterned into an arbitrary shape by forming a pattern used during etching as needed.

After the artificial lattice layer is patterned in step 210, in step 212 SiNx, S
A protective film such as iO2 is formed. Next, in step 214, contact holes for the electrodes are formed by etching. Then, in step 216, an Al film as an electrode material is deposited, and then in step 218, an electrode pattern is formed by etching, and the formation of the GMR element 16 on the flexible substrate 14 is completed.

The GMR element 16 having an arbitrary pattern can be formed on the flexible substrate 14 by the procedure for forming the GMR element 16 described above. As a result, the flexible substrate 14 can be arranged in a cylindrical shape so as to be curved, and the GMR element 16 and the magnet 13 can be opposed to each other in the radial direction.

In the above embodiment, the area F (x) is changed according to x by forming the GMR element 16 so that the width in the axial direction changes according to the position in the circumferential direction. However, the present invention is not limited to this. For example, as shown in FIG.
6 may be formed in a triangular wave shape extending in the circumferential direction, and the cycle thereof may be changed according to the position in the circumferential direction. Figure 7
In, the period is increased from left to right in the figure. Therefore, when the magnet 13 moves from left to right in FIG. 7 due to the rotation of the rotor 12, G
The area of the region of the MR element 16 where the magnetic field is applied by the magnet 13 gradually decreases. Therefore, as described above, the GM is adjusted so that this area changes linearly according to the position of the magnet 13.
By changing the period of the wavy line shape of the R element 16, it is possible to obtain an output signal that linearly changes according to the rotation angle of the rotor 12.

As described above, the GMR element 16 can be easily patterned into an arbitrary shape by etching. Therefore, in the present embodiment, it is easy to form the pattern as shown in FIG. 2 or 7 so that the area of the region where the magnetic field acts changes linearly according to the position in the circumferential direction. .

In the above embodiment, the magnetic type rotation sensor 10 is realized by arranging the flexible substrate 14 on which the GMR element 16 is formed in a cylindrical shape around the rotor 12 to which the magnet 13 is fixed. However, as shown in FIG. 8, the linear movement position of the moving body 38 is set by arranging the flexible substrate 14 in a plane and arranging it so as to face the magnet 13 fixed to the moving body 38 that moves linearly. It is also possible to realize a magnetic linear sensor for detecting.

Next, with reference to FIG. 9, the structure of the magnetic rotation sensor 40 according to the second embodiment of the present invention will be described. Note that, in FIG. 9, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. In this embodiment, the rotor 12 is connected to a rotating body that continuously rotates, such as an axle of a vehicle. A magnet 43 polarized in two poles is fixed to the rotor 12 in a direction perpendicular to the axial direction of the rotor 12. The magnet 43 is the rotor 1
It may be formed by directly magnetizing 2. Rotor 1
GMR elements 46 and 48 are formed on the cylindrical flexible substrate 14 arranged around the substrate 2. GMR
The elements 46 and 48 are formed so as to extend in the circumferential direction of the flexible substrate 14, and are provided so that their center positions in the circumferential direction are separated from each other by 90 °.

FIG. 10 shows a state in which the flexible substrate 14 is developed on a plane. GMR elements 46 and 48 are shown in FIG.
It may be formed in a rectangular shape as indicated by 0, or may be formed in any other pattern.
The GMR elements 46 and 48 are connected by a conductor 49. Further, electrodes 50 and 52 are connected to the end portions of the GMR elements 46 and 48 on the opposite side to the connection portion by the conductor 49, respectively.

According to this structure, in the state shown in FIG. 9, the GMR element 46 faces the N pole of the magnet 43,
The element 48 faces the boundary between the two poles of the magnet 43. Therefore, the magnetic field generated by the magnet 43 acts substantially perpendicular to the film direction of the GMR element 46, and the GMR element 48.
Acts substantially parallel to the film direction of. Therefore, in the state shown in FIG. 9, the resistance value of the GMR element 48 is reduced, and
The resistance value of the R element 48 is not reduced. When the rotor 12 rotates 90 ° in the clockwise direction in FIG. 9 from this state, the GMR element 46 faces the boundary portion between the two poles of the magnet 43, and the GMR element 48 faces the S pole of the magnet 43. In this state, contrary to the state shown in FIG.
The resistance value of the element 48 has been reduced and the resistance value of the GMR element 46 has not been reduced. Further, when the rotor 12 rotates 90 ° in the clockwise direction in FIG. 9 from this state, the GMR
The element 46 faces the south pole of the magnet 43, and the GMR element 48 faces the boundary between the two poles of the magnet 43.
The resistance value of the R element 48 is reduced, and the resistance value of the GMR element 46 is not reduced. Thus, GMR
The resistance values of the elements 46 and 48 are 1 with respect to the rotation angle of the rotor 12 when the phases are 90 ° out of phase with each other.
It will change every 80 °.

In FIG. 11, changes in the resistance value R1 of the GMR element 46 and the resistance value R2 of the GMR element 48 with respect to the rotation angle φ of the rotor 12 are indicated by dotted lines, respectively, and the sum of these resistance values, the electrode 50, Resistance value R between 52 (= R1 +
The change in R2) is shown by a solid line. As mentioned above, R1 and R2
Changes in a cycle of 180 ° with respect to φ, with their phases deviated from each other by 90 °. Therefore, as shown in FIG. 11, R is φ
With a 90 ° cycle. Therefore, such an electrode 4
The rotation angle φ of the rotor 12 can be detected from the change in the resistance R between 6 and 48.

FIG. 12 shows an example of a circuit configuration for detecting the rotation angle φ of the rotor 12 by the magnetic rotation sensor 40. In FIG. 12, a constant current source 50 is connected to the electrode 46, whereby the resistance between the electrodes 46 and 48 is converted into a voltage signal. The voltage signal is binarized by a binarization circuit 52 with an appropriate threshold value and converted into a pulse signal. Then, the counting circuit 54 counts the number of pulses of the pulse signal. As described above, the electrode 4
The resistance value between 8 and 50 is 9 with respect to the rotation angle of the rotor 12.
Since it changes in a 0 ° cycle, one pulse is generated every 90 ° rotation of the rotor 12. Therefore, when the number of pulses is N, the rotation angle of the rotor 12 is 90 · N °, that is, the rotation number of the rotor 12 is N / 4 rotations.

In the magnetic type rotation sensor 40 of this embodiment, as in the case of the magnetic type rotation sensor 10 described above, G
The MR elements 46 and 48 make the rotor 1
2 are opposed to each other in the radial direction. As a result, also in this embodiment, as in the first embodiment, the magnetic rotation sensor 4 is
It is possible to reduce the dimension of 0 in the axial direction.

As described above, according to the magnetic rotation sensor 40, a predetermined number of pulses are generated for one rotation of the rotor 12 in the output signal. Therefore, the rotation speed of the rotor 12 can be detected by measuring the number of pulses per unit time. In this case, in order to improve the measurement resolution, it is preferable that the number of pulses per rotation is large. In the magnetic rotation sensor 40 described above, four peaks are obtained per rotation due to the configuration of the magnet 43 and the GMR elements 46 and 48 as described above. As a result, the measurement resolution of the magnetic rotation sensor 40 is improved, and it is possible to measure the rotation speed with high accuracy even when the rotation speed of the rotor 12 is low. As described above, the magnetic rotation sensor 40 of the present embodiment can be particularly preferably used for measuring the rotation speed of the rotating body.

In the above embodiment, the rotor 12
Although the magnet 43 polarized in the direction perpendicular to the axial direction of is used, the present invention is not limited to this.
For example, as shown in FIG. 13, magnets 53 and 54 polarized in the axial direction or the circumferential direction of the rotor 12 are provided on both sides of the rotor 12 in the diametrical direction (FIG. 13 shows a case where the magnets are polarized in the circumferential direction). Is also provided, it is possible to obtain the same effect as in the above embodiment. In this case, of the GMR elements 46 or 48, the GMR element facing either of the magnets 53, 54 (in the state shown in FIG.
The magnetic field generated by the magnet 53 or 54 is applied to the R element 46) by the GMR.
It acts parallel to the device film, reducing its resistance.

Further, in the magnetic rotation sensor 40 of this embodiment, four pulses are obtained for one rotation of the rotor 12 by using the magnet 43 polarized in two poles. However, the present invention is not limited to this.
It is also possible to increase the number of polarizations of the magnet to increase the number of pulses per one rotation of the rotor as shown in FIG. FIG. 14 shows the configuration of a magnetic rotation sensor 60 including a magnet 63 polarized into four poles, which is a third embodiment of the present invention.

In FIG. 14, the rotor 12 has a magnet 6 which is uniformly polarized into four poles in a plane perpendicular to the axis of the rotor 12.
3 is fixed. The GMR elements 70 and 72 are formed so as to extend in the circumferential direction of the flexible substrate 14, and are provided such that their center positions in the circumferential direction are separated from each other by 135 °. GMR elements 70 and 72
May be formed in a rectangular shape, or may be formed in any other pattern. The GMR elements 70 and 72 are connected by a conductor 74. Also,
Electrodes 76 and 78 are connected to the ends of the GMR elements 70 and 72 on the side opposite to the connection site by the conductor 74, respectively.

With such a configuration, in the state shown in FIG. 11, the GMR element 70 faces the boundary between the poles 63 _N1 and 63 _S1 of the magnet 63, and the GMR element 72 has the N pole 63 _{N2 of the} magnet 63.
And is facing. Therefore, the resistance value of the GMR element 70 is reduced and the resistance value of the GMR element 72 is not reduced. When the rotor 12 rotates 45 ° clockwise in this state from this state, the GMR element 70 faces the S pole 63 _S1 of the magnet 63, and the GMR element 72 causes the pole 6 of the magnet 63 to move.
It is in a state of facing the boundary of 3 _N2 and 63 _S2 . Therefore, the resistance value of the GMR element 70 is not reduced, and the resistance value of the GMR element 72 is reduced. Further, from this state, the rotor 12 is rotated 45 ° clockwise in FIG.
When rotated, the GMR element 70 causes the poles 63 _S1 , 6 of the magnet 63 to
The GMR element 72 _faces the boundary of 3 _N2 , and the GMR element 72 is S of the magnet 63.
It faces pole 63 _S2 . In this state, the resistance value of the GMR element 70 is reduced again, and the resistance value of the GMR element 72 is not reduced.

Thus, the resistance value R3 of the GMR element 70 is
And the resistance value R4 of 72 is 90 ° with respect to the rotation angle of the rotor 12 when the phases are shifted from each other by 45 °.
It will change in a cycle. FIG. 15 shows the GMR element 7
The resistance values R3 and R4 of 0 and 72 are shown by a broken line, and the resistance between the electrodes 76 and 78, that is, R3 + R4 is shown by a solid line. As shown in FIG. 15, the resistance between the electrodes 76 and 78 changes in a cycle of 45 ° with respect to the rotation of the rotor 12.
Therefore, as in the case of the magnetic rotation sensor 40 described above, by converting the change in the resistance value into a pulse signal, eight pulses can be obtained for one rotation of the rotor 12. In this way, by increasing the polarization number of the magnet, the measurement resolution of the magnetic rotation sensor can be further improved.

In the magnetic rotation sensor 60 of this embodiment, instead of the magnet 63 polarized in the direction perpendicular to the axial direction of the rotor 12, 90 is provided on the outer peripheral portion of the rotor 12.
At four-degree intervals, four axially or circumferentially polarized magnets may be fixed. In this case, the GMR elements 70 and 72
Among them, the resistance value of the GMR element facing any of these magnets is reduced.

Next, referring to FIG. 16, the structure of the magnetic rotation sensor 80 according to the fourth embodiment of the present invention will be described.
FIG. 16 shows a configuration diagram of the magnetic rotation sensor 80. 16, the same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 16, a magnet 83 polarized in two poles in a direction perpendicular to the axis of the rotor 12 is fixed to the rotor 12. The flexible board 14 has four
Two GMR elements 84, 86, 88 and 90 are deposited. The GMR elements 84, 86, 88, and 90 are formed at regular intervals of 90 ° in the circumferential direction, and are connected to each other at their adjacent portions. An electrode 92 is formed at the connection between the GMR elements 84 and 86, and a voltage source 96 is connected to the electrode 92. GMR elements 88 and 90
An electrode 94 is formed at a connection portion with and the electrode 94 is connected to the ground. Further, an electrode 93 is formed at the connecting portion between the GMR elements 86 and 88, and an electrode 95 is formed at the connecting portion between the GMR elements 84 and 90. A voltmeter 98 is connected between the electrodes 93 and 95. FIG. 17 shows the configuration of the GMR elements 84 to 90 and the electrodes 92 to 95 in a state where the flexible substrate 14 is expanded on a plane. Incidentally, in FIG. 14, the GMR elements 84 to 90 are
Is patterned in a triangular wave shape, but may be patterned in any other shape such as a rectangle.

With this structure, the magnetic fields generated by the magnets 83 act on the GMR elements 84 and 88 facing each other with the rotor 12 in between with equal magnitude. The same applies to the GMR elements 86 and 90. Therefore, when the magnetic field generated by the magnet 83 is rotated by the rotation of the rotor 12, the resistance values of the GMR elements 84 and 88 and the GMR elements 86 and 88 change while being maintained at the same values. FIG. 18 shows the resistance value R of the GMR elements 84 and 88 with respect to the rotation angle α of the rotor 12.
5 and changes in the resistance value R6 of the GMR elements 86 and 90 are indicated by the solid line and the broken line, respectively. However, each rotation α
Indicates the rotation angle of the rotor 12 in the clockwise direction in the figure based on the state shown in FIG. As described above, the resistance value of the GMR element in which the N pole or the S pole of the magnet 83 is opposed is not decreased, and the resistance value of the GMR element in which the boundary portions of both poles of the magnet 83 are opposed to the GMR element is decreased. Therefore, as shown in FIG. 18, when the rotation angle α of the rotor 12 is 45 ° and 225 °, R5 is maximum and R6 is minimum, and α
Is 135 ° and 315 °, R5 is minimum and R6 is maximum.

FIG. 19 shows an electric circuit diagram equivalent to FIG. As shown in FIG. 19, when the voltage generated by the voltage source 96 is E, the potential of the electrode 93 is E · (R5 / R5 + R
6), the potential of the electrode 95 becomes E · (R6 / R5 + R6). Therefore, the potential difference between electrodes 93 and 95 is
5 based on E ・ (R5-R6) / (R5 + R6)
Becomes The potential difference is measured by the voltmeter 98 and output as the output signal Vb. FIG. 20 shows the relationship between α and Vb obtained by using the relationship between the rotation angle α of the rotor 12 shown in FIG. 18 and R5 and R6. As shown in FIG. 20, positive and negative peaks appear alternately in Vb every 90 ° of α. After rectifying this signal Vb, 2 is set at an appropriate threshold value.
By digitizing, one pulse is obtained for every 90 ° of the rotation angle α of the rotor 12. Therefore, by counting the number of such pulses, the magnetic rotation sensor 40 described above is
The rotation speed of the rotor 12 can be detected in the same manner as in the cases of 60 and 60.

By the way, generally, the resistance value of the GMR element changes according to the temperature change. For example, a predetermined reference temperature T
The resistance values of the GMR elements 84 and 88 at 0 are R50, G
Assuming that the resistance values of the MR elements 86 and 90 are R60, these resistance values R5 and R6 at the temperature (T0 + ΔT) are
R50 ・ (1 + β ・ ΔT), R60 ・ (1 + β ・
ΔT). Therefore, Vb = E. (R5-R6) / (R5 + R6) = E. {R50. (1 + .beta..DELTA.T) -R60. (1 + .beta..DELTA.T)} / R50. (1 + .beta..DELTA.T) + R60. (1 + .beta..DELTA.T) ) = E. (R50-R60) / (R50 + R60) (2) As can be seen from the equation (2), Vb is not affected by the change in the resistance value of the GMR elements 84 to 90 due to the temperature change. Therefore, in the magnetic rotation sensor 80, the output signal is prevented from changing even when the resistance value of the GMR element changes due to the temperature change. In this way, in this embodiment, the magnetic rotation sensor 80 having excellent temperature characteristics is realized.

Next, FIG. 21 shows the structure of a magnetic type rotation sensor 100 according to a fifth embodiment of the present invention. Note that FIG.
1, the same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. As shown in FIG. 21, the rotor 1
A magnet 103 polarized in the axial direction of the rotor 12 is fixed to the outer peripheral portion of the rotor 2. The flexible substrate 14 includes
Six GMR elements 104 to 114 are formed at equal intervals in the circumferential direction. The electrodes 124 to 134 are connected to one ends of the GMR elements 104 to 114, respectively. The other ends of the GMR elements 104 to 114 are all connected to the ground. FIG. 22 shows the GMR element 10 with the flexible substrate 14 developed on a plane.
4 to 114 and electrodes 124 to 134 are shown. FIG.
2, the GMR elements 104 to 114 are patterned in a triangular wave shape, but may be patterned in any other shape such as a rectangle.

According to this structure, the magnet 103 of the GMR elements 104 to 114 is selected depending on the rotational position of the rotor 12.
A magnetic field acts on the GMR element facing to, and its resistance value decreases. For example, in the state shown in FIG. 21, the GMR element 1
The resistance value of 04 has decreased. As described above, in the magnetic rotation sensor 100, the six GMR elements 104 to 114 are arranged at equal intervals in the circumferential direction. Therefore, the resistance value is reduced every time the rotor 12 rotates by 60 °.
The R element will move to the next. Therefore, for example, the rotational position of the rotor 12 can be detected by sequentially measuring the resistance values of the electrodes 114 to 124 while switching them by a multiplexer and detecting which GMR element has the decreased resistance value.

The magnetic rotation sensor 100 of this embodiment is used.
In the above, the measurement resolution of 60 ° is obtained by providing the six GMR elements 104 to 114.
The measurement resolution can also be improved by increasing the number of elements. FIG. 23 shows an example in which the arrangement of the GMR elements shown in FIG. 22 is expanded two-dimensionally. As shown in FIG. 23, 30 GMR elements 130 _{-1 to} 130 _-30 are formed in a matrix with 6 in the horizontal direction and 5 in the vertical direction in the figure. The measurement resolution can be improved by increasing the number of GMR elements. Electrodes 130 _{-1 to} 130 _-30 are provided on one of the ends of each GMR element.
, And the other end of each GMR element is connected to ground. As in the case of the magnetic rotation sensor 10 shown in FIG. 21, the flexible substrate 14 on which the GMR element and the electrodes are formed is arranged in a cylindrical shape around the rotor 12 to which the magnet 103 is fixed. However, by detecting which GMR element has a reduced resistance value, it is possible to detect the rotational position and the axial movement position of the rotor 12.

Further, as shown in FIG. 23, the flexible substrate 14 on which the GMR element and the electrodes are formed is arranged so as to face a magnet fixed to a moving body which makes a two-dimensional planar motion, so that the moving body is moved. It is also possible to measure the two-dimensional position of. In the above embodiment, the GMR
The elements 16, 46, 48, 70, 72, 84 to 90, and 104 to 114 correspond to the magnetoresistive elements described above.

[0056]

As described above, according to the first aspect of the invention, the axial size of the rotor of the magnetic rotation sensor can be reduced. According to the second aspect of the present invention,
It is possible to reduce the axial dimension of the rotor of the magnetic rotation sensor and obtain an output signal that changes according to the rotation angle of the rotor.

According to the third and fourth aspects of the invention, the axial dimension of the rotor of the magnetic rotation sensor can be reduced and the magnetoresistive element can be easily formed. Further, according to the invention of claim 5, the axial size of the rotor of the magnetic rotation sensor can be reduced, and an output signal that repeats increase and decrease a plurality of times per one rotation of the rotor can be obtained. Thereby, the rotation speed of the rotating body can be detected with high accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a magnetic rotation sensor that is a first embodiment of the present invention.

FIG. 2 is a diagram showing a state in which the flexible substrate according to the present embodiment is developed in a planar shape.

FIG. 3 is a diagram showing a relationship between a magnetic field acting on a GMR element and a resistance value.

FIG. 4 is a circuit diagram of a circuit for converting the resistance value of the GMR element of the magnetic rotation sensor of this embodiment into a voltage signal.

FIG. 5 is a diagram showing a relationship between a rotation angle of a rotor and an output signal of the magnetic rotation sensor of this embodiment.

FIG. 6 is a diagram showing a manufacturing process of a GMR element of this example.

FIG. 7 is a diagram showing another example of the pattern of the GMR element of the present embodiment.

FIG. 8 is a configuration diagram when the principle of the present embodiment is applied to a linear sensor.

FIG. 9 is a configuration diagram of a magnetic rotation sensor that is a second embodiment of the present invention.

FIG. 10 is a diagram showing a state in which the flexible substrate according to the present embodiment is developed in a planar shape.

FIG. 11 is a diagram showing the relationship between the rotation angle of the rotor of the magnetic rotation sensor of this embodiment, the resistance value of each GMR element, and the resistance value between the electrodes.

FIG. 12 is a configuration diagram of a circuit for converting a change in resistance value between electrodes of the magnetic rotation sensor of the present embodiment into a pulse signal.

FIG. 13 is a diagram showing an example in which a magnet having another configuration is used in the magnetic rotation sensor of this embodiment.

FIG. 14 is a configuration diagram of a magnetic rotation sensor that is a third embodiment of the present invention.

FIG. 15 is a diagram showing the relationship between the rotation angle of the rotor of the magnetic rotation sensor of this embodiment, the resistance value of each GMR element, and the resistance value between electrodes.

FIG. 16 is a configuration diagram of a magnetic rotation sensor that is a fourth embodiment of the present invention.

FIG. 17 is a diagram showing a state in which the flexible board of the present embodiment is developed in a planar shape.

FIG. 18 is a diagram showing the relationship between the rotation angle of the rotor of the magnetic rotation sensor of this embodiment and the resistance value of each GMR element.

FIG. 19 is an electric circuit diagram equivalent to the magnetic rotation sensor of the present embodiment.

FIG. 20 is a diagram showing the relationship between the rotation angle of the rotor of this embodiment and the output signal.

FIG. 21 is a configuration diagram of a magnetic rotation sensor that is a fifth embodiment of the present invention.

FIG. 22 is a diagram showing a state in which the flexible board of the present embodiment is developed in a planar shape.

FIG. 23 is a diagram showing the configuration of a flexible substrate when the magnetic rotation sensor of this embodiment is extended to a two-dimensional sensor.

[Explanation of symbols]

10, 40, 60, 80, 100 Magnetic rotation sensor 12 Rotor 13, 43, 53, 54, 63, 83, 103 Magnet 14 Flexible substrate 16, 46, 48, 70, 72, 84-90, 104-
114, 130 _-1 to 1 30 _-30 GMR element

Claims (5)

[Claims] 1. A magnetic rotation sensor comprising: a magnet that rotates together with the rotation of a rotating body; and a magnetoresistive element whose resistance value changes when a magnetic field from the magnet acts. A magnetic rotation sensor, wherein the magnetic rotation sensor is provided so as to be separated from the rotating body in a radial direction thereof and to face the magnet. 2. The magnetoresistive element is formed such that an area of a region where a magnetic field of the magnet acts changes in accordance with a rotation angle of the rotating body from a reference position. The magnetic rotation sensor described. 3. The magnetoresistive element is formed in a band shape such that a width in a direction parallel to an axis of the rotating body changes according to a position in the circumferential direction of the rotating body. The magnetic rotation sensor according to claim 2. 4. The magnetic rotation sensor according to claim 2, wherein the magnetoresistive element is provided so that the areal density changes according to the position of the rotating body in the circumferential direction. 5. At least two of said magnetoresistive elements,
The magnetic rotation sensor according to claim 1, wherein the magnetic field applied by the magnet is provided so as to be maximum at different rotation positions of the rotating body.