JPH11316135A - Magnetism detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a sensor signal processing part, and to detect rotation of a detected object. SOLUTION: This device has a bias magnet 6 for generating a magnetic field toward a gear 2 with a magnetic material, a magnetic resistant element 3 arranged between the bias magnet 6 and the gear 2, having half-bridged constitution connected in series with the first magnetic resistant element 3a and the second magnetic resistant element 3b having respectively multilayered films GMR(giant magnetic resistant element), and having the first element 3a and the second element 3b with respective resistance values which vary in reverse phase each other by variation of the magnetic field impressed to the films GMR in response to movement of the gear 2, and a sensor signal processing part, 5 for outputting output value change due to the variation of a resistance value in the magnetic resistant element 3, as a movement detecting output for the gear 2. The bias magnet 6, the element 3, and the sensor signal processing part 5 are supported integrally on a supporting base plate 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-sensitivity magnetic detecting device for detecting a movement, a rotation, and the like of an object to be detected by utilizing a resistance change of a magnetoresistive element.

[0002]

2. Description of the Related Art A conventional magnetic detecting device is disclosed in
2. Description of the Related Art There is known a magnetic detection device as disclosed in Japanese Patent Publication No. 174490.

[0003] As shown in FIG. 8, the magnetic detecting device includes a gear 100, a hollow bias magnet 104 for generating a bias magnetic field toward the gear 100, and a magnetoresistive element 10.
3 holds the bias magnet 1
04 through the through hole. As shown in FIG. 9, the magnetoresistive element 103 is configured such that the first magnetoresistive element 111 and the second magnetoresistive element 112 form an angle of ± 45 degrees with the bias magnetic field direction W. Have been.

In this magnetic detection device, the resistance value of each magnetoresistive element changes in the opposite phase due to a change in the direction of the bias magnetic field according to the gear rotation. Also, the arrangement of the magnetoresistive elements at 45 degrees prevents the occurrence of waveform breakage. The output value of the magnetoresistive element 103 corresponds to each of the magnetoresistive elements 111 and 112.
And is supplied to the signal processing circuit 114.

As a conventional magnetic detection signal processing device corresponding to the signal processing circuit 114, there is known a sensor signal processing device disclosed in Japanese Patent Laid-Open Publication No. Hei 6-300584. The operation of the sensor signal processing device will be described as the operation of the signal processing circuit 114.
Amplifies the detection output from the magnetic resistance unit 103 with a predetermined gain, holds the peak value and the bottom value, sets a threshold based on the peak value and the bottom value, and binarizes the detection output based on the threshold. Output.

As a result, the rotation speed of the gear 100 (the teeth 10
1), and the number of rotations of the gear 100 can be detected by counting the number of pulses output from the signal processing circuit 114 in a subsequent stage such as a counter.

[0007]

However, Japanese Patent Application Laid-Open No.
A magnetic detection device as disclosed in US Pat.
It is necessary to arrange so that the angle between the bias magnetic field direction and each of the magnetoresistive elements 111 and 112 is 45 degrees. When the angle of the bias magnetic field applied to each of the magnetoresistive elements 111 and 112 deviates from 45 degrees, each resistance value changes in reverse, so that the potential taken out from the middle point of connection greatly changes.

The deviation of the bias magnetic field angle from 45 degrees is as follows:
The positional relationship when the magnetoresistive element is assembled to the bias magnet, or the positional relationship when the magnetic detecting device consisting of the magnetoresistive device, the bias magnet, and the molding material is attached to the gear, or the magnetic detecting device is attached to the gear This is caused by a shift in the positional relationship between the magnetic detection device and the gear due to the eccentricity of the gear after being attached.

When the respective positional relations are inclined in the α direction in the figure with respect to the center line (diameter direction of the gear 100) shown in FIG. The direction of the magnetic field biased by 111 and 112 deviates from 45 degrees, and the midpoint potential (the potential intermediate between the peak and the bottom of the sin-wave sensor signal due to the rotation of the gear) fluctuates greatly.

When the output from the magnetoresistive section 103 in which the midpoint potential greatly fluctuates is input to the signal processing circuit 114 at the subsequent stage, the pulse output from the signal processing circuit 114 cannot change the duty ratio or cannot output the pulse. And so on. For this reason, there has been a problem that the magnetic detection device is required to have high assembling accuracy and mounting accuracy. Further, the conventional magnetism detecting device has a bias magnet 10
Since a hollow shape is provided as 4, there is a problem that the outer dimensions of the magnetic detection device become large.

Therefore, as a solution to this problem,
The present applicant filed Japanese Patent Application No. 9-1273 on May 16, 1997.
No. 11 has filed an application for a magnetic detection device and a magnetic detection signal processing device.

As shown in FIG. 10, the magnetic detecting device includes a flat bias magnet 206 for applying a bias magnetic field to the gear 202, a half-bridge or full-bridge magnetoresistive element 203, and a sensor signal. The processing unit 205 is provided on the support substrate 204. A sensor signal corresponding to a change in the resistance value of each of the magnetoresistive elements 203a and 203b due to the rotation of the gear 202 is taken out, binarized by the sensor signal processing unit 205, and output as a sensor pulse.

Even if the mounting position shifts or tilts, the bias magnetic field applied to each of the magneto-resistive elements 203a and 203b does not shift so much, so that a change in the midpoint potential of the sensor signal can be prevented, and the assembling accuracy can be improved. Be relaxed. Further, since a flat bias magnet is used, the outer dimensions of the sensor can be reduced.

Further, the sensor signal processing unit 205
As shown in FIG. 7, an amplifying unit 211 for amplifying a sensor signal extracted as a voltage change at a connection point of each of the magnetoresistive elements 203a and 203b, a peak hold circuit 216 for holding a peak value of the sensor signal from the amplifying unit 211, and A holding unit 212 including a bottom hold circuit 217 for holding a bottom value of the sensor signal;
Threshold value generating section 213 which outputs the divided voltage values of the peak value and the bottom value of the sensor signal held by the controller as a threshold signal
And

The sensor signal processing section 205 binarizes the sensor signal from the amplifying section 211 based on the threshold signal from the threshold generating section 213 and outputs a sensor pulse. Peak hold circuit 216 and bottom hold circuit 2 based on sensor pulse
And an edge detection unit 215 for generating 17 reset signals.

The sensor signal processing unit 205 forms a high-level threshold signal and a low-level threshold signal based on the peak hold value and the bottom hold value, and generates a sensor signal based on each of the threshold signals. Because of the binarization, even if the midpoint potential of the sensor signal fluctuates, the binarized sensor pulse can be output accurately without being affected by the fluctuation.

However, the aforementioned Japanese Patent Application No. Hei 9-127 is disclosed.
Each magnetic resistance element 2 provided in the magnetic detection device of No. 311
The amount of change (rate) of the resistance value due to the change in the magnetic field in 03a and 203b is very small, at most about 4%.

For this reason, the amplitude of the sensor signal is small, and as shown in FIG. Therefore, a large-scale sensor signal processing unit 20 including a peak hold circuit 216, a bottom hold circuit 217, and the like in order to follow the fluctuation of the midpoint potential.
5 had to be provided. As a result, the sensor signal processing section has a complicated circuit configuration.

The present invention realizes a simple sensor signal processing section by using a magnetoresistive element having a large rate of change in resistance value due to a change in magnetic field angle, and a magnetic detection apparatus capable of detecting rotation of a detection target. The task is to provide.

[0020]

The magnetic detecting device according to the present invention has the following arrangement to solve the above-mentioned problems. The invention according to claim 1 is a bias magnet that generates a magnetic field toward a detection target having a magnetic material, and is disposed between the bias magnet and the detection target, and includes at least a first thin film and a second thin film. A half-bridge configuration in which a first magnetoresistive element and a second magnetoresistive element having a multilayer film in which thin films are alternately laminated a plurality of times are connected in series, and the multilayer film is formed in accordance with the movement of the detection target. Magnetoresistive means in which the respective resistance values of the first and second magnetoresistive elements change in opposite phases due to a change in the magnetic field applied to
A sensor signal processing unit that outputs a change in an output value due to a change in the resistance value of the magnetic resistance unit as a motion detection output of the detection target, and the bias magnet, the magnetic resistance unit, and the sensor signal processing unit are integrally supported. A supporting substrate.

According to the first aspect of the present invention, when the magnetic field of the bias magnet is applied to the first and second magnetoresistive elements having the multilayer film and the magnetic field angle changes due to the movement of the detection target, Due to the change in the magnetic field, the resistance values of the first magnetoresistive element and the second magnetoresistive element greatly change in opposite phases.

That is, since the magnetoresistive means having a multilayer film having a large resistance change rate due to a change in the magnetic field angle is used, the change in the output value due to the change in the resistance value of the magnetoresistive means is several times larger than the conventional one. The rotation of the detection target can be detected by a simple sensor signal processing unit.

According to a second aspect of the present invention, the sensor signal processing section is configured to determine in advance the output value from the magnetoresistive means that causes a change in the resistance value due to a change in the magnetic field according to the movement of the object to be detected. And a comparing means for comparing the output value with the threshold value, binarizing the output value, and outputting the binarized value.

According to the second aspect of the present invention, in the sensor signal processing section, the comparing means determines the output value from the magnetoresistive means which causes a change in the resistance value due to a change in the magnetic field according to the movement of the object to be detected, and the predetermined value. And compare the output value to 2
Since the output is made into a value, the rotation of the detection target can be detected by a simple sensor signal processing unit.

According to a third aspect of the present invention, the object to be detected is a rotation detecting body in which convex portions and concave portions are alternately provided on the circumference, and the first magnetic member disposed on the support substrate. The distance between the resistance element and the second magnetic resistance element is set substantially equal to the distance between the convex part and the concave part of the rotation detecting body.

According to the third aspect of the present invention, the distance between the first and second magnetoresistive elements is set to be substantially the same as the distance between the convex and concave portions of the rotation detecting body. The rotation of the body changes the resistances of the first and second magneto-resistive elements in opposite phases, so that the resistance between the first and second magneto-resistive elements is changed from the midpoint of the first and second magneto-resistive elements. A sensor signal having a large amplitude according to the motion of the detection target can be obtained.

According to a fourth aspect of the present invention, the magneto-resistive means is disposed so as to be inclined so that an angle between the magneto-resistive means and the direction of the magnetic field becomes a predetermined angle, so that a change in resistance due to a change in the magnetic field is reduced. growing.

According to the fifth aspect of the present invention, when the predetermined angle is within an angle range of approximately 70 ° to approximately 80 °, a change in the resistance value due to a change in the magnetic field is further increased.

According to a sixth aspect of the present invention, the first thin film is a NiFeCo thin film, and the second thin film is a CuFe thin film.
High sensitivity can be obtained by being a thin film.

According to a seventh aspect of the present invention, the first and second magnetoresistive elements have the same resistance change rate with respect to temperature change.

According to the seventh aspect of the present invention, since the resistance change rates of the first and second magnetoresistive elements change with the same characteristic with respect to a change in temperature, the midpoint does not change even if the temperature changes. Since the potential does not change, it is possible to suppress a change in the midpoint potential due to a temperature change.

[0032]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a magnetic detecting device according to an embodiment of the present invention. FIG. 1 shows a configuration diagram of a magnetic detection device according to an embodiment.

The magnetic detecting device shown in FIG. 1 detects the rotational movement of the gear 2 to be detected. Gear 2
In the circumference of the gear 2, convex portions 1a and concave portions 1b as teeth are provided alternately, and near the circumference of the gear 2, a flat portion 4
An L-shaped support substrate 4 composed of a and an inclined portion 4b is arranged.

On one surface of the bent portion 4b of the support substrate 4, a first magnetoresistive element 3a and a second magnetoresistive element
b, and the bias magnet 6 is attached to the other surface of the bent portion 4b and one surface of the flat portion 4a. The bias magnet 6 generates a bias magnetic field toward the gear 2 having a magnetic body, and is magnetized in a direction toward the gear 2. The sensor signal processing unit 5 is attached to the other surface of the flat part 4a.

The first and second magnetoresistive elements 3a and 3b constitute the magnetoresistive element 3. The distance between the first magnetoresistive element 3a and the second magnetoresistive element 3b arranged on the support substrate 4 is adjusted to the pitch between the convex portion 1a and the concave portion 1b of the gear 2.

The bent portion 4b of the support substrate 4 is inclined at a predetermined angle, for example, about 90 ° with respect to the flat portion 4a. And the first magnetoresistive element 3a and the second
Through the magnetoresistive element 3b.

The first magnetoresistive element 3a and the second magnetoresistive element 3b change their resistance by the change of the bias magnetic field (magnetic field deflection angle θ ') in accordance with the movement of the gear 2 by the convex portion 1a and the concave portion 1b. To occur. Since the first magnetoresistive element 3a and the second magnetoresistive element 3b are arranged in accordance with the pitch between the convex portion 1a and the concave portion 1b of the gear 2, the resistance values change in opposite phases. ing.

The sensor signal processing section 5 takes out a change in the resistance value of each of the magnetoresistive elements 3a and 3b due to the rotation of the gear 2 as a midpoint voltage, binarizes the midpoint voltage with a predetermined threshold value, and converts the voltage into a sensor pulse. Output.

FIG. 2 shows the configuration of the magnetoresistive element 3 according to the embodiment. The magnetoresistive element 3 shown in FIG. 1 includes a first magnetoresistive element 3a having a comb-shaped electrode pattern 7a,
And a second magnetoresistive element 3b having a comb-shaped electrode pattern 7b.

The electrode 8a is connected to one end of the electrode pattern 7a, the electrode 8c is connected to one end of the electrode pattern 7b, the electrode 8b is connected to the middle point a between the electrode pattern 7a and the electrode pattern 7b, The midpoint voltage is extracted from 8b.

FIG. 3 shows the first magnetoresistive element 3 of the embodiment.
a and a cross-sectional view of the second magnetoresistive element 3b. The first magnetoresistive element 3a and the second magnetoresistive element 3b are composed of a giant magnetoresistive element (GMR) composed of a multilayer film, and generate a resistance change by a change in a bias magnetic field.

The first magnetoresistive element 3a and the second magnetoresistive element 3b include an Fe thin film 11, a NiFeCo thin film 13 (thickness 15 °) laminated on the Fe thin film 11,
It has a Cu thin film 15 (thickness 21 °) laminated on the iFeCo thin film 13 and is formed by laminating 20 layers of the NiFeCo thin film 13 and the Cu thin film 15.

Each of the first magnetoresistive element 3a and the second magnetoresistive element 3b has the same temperature characteristic indicating a change in resistance value with respect to an external temperature change. Fluctuations can be suppressed.

FIG. 4 shows a configuration diagram for measuring the rate of change in resistance when a constant current is applied to change the magnetic field angle. In FIG. 4, a first magnetoresistive element 3a having a multilayer film GMR (same for the second magnetoresistive element 3b) includes:
The constant current source 21 is connected.

The direction parallel to the multilayer film GMR of the first magnetoresistive element 3a (the longitudinal direction of each thin film) is defined as a magnetic field angle of 0 °, and the direction perpendicular to the multilayer film GMR (the direction perpendicular to the longitudinal direction) is defined. The magnetic field angle is 90 °.

FIG. 5 shows the resistance change rate with respect to the magnetic field angle when the magnetic field angle is changed from 0 ° to 90 °.
In FIG. 5, the horizontal axis represents the magnetic field angle, and the vertical axis represents the resistance change rate.

The bias magnetic field generated by the magnet 6 strength H, for example, a predetermined magnetic field intensity H ₁ is applied to the first magnetoresistive element 3a and the second magnetoresistive element 3b, from up to 90 ° is the magnetic field angle field angle 0 ° When the resistance changes, the resistance change rate is about 10.5% at the maximum.

Since the conventional resistance change rate is about 4%,
The rate of change in resistance of the first magnetoresistive element 3a and the second magnetoresistive element 3b is about twice or more the rate of change in resistance of a conventional Ni-Co based magnetoresistive element. For this reason, it is possible to provide the magnetoresistive element 3 capable of obtaining a sensor output twice or more as compared with the conventional one.

FIG. 7 is a circuit diagram of the sensor signal processing unit 5 of the magnetic detection device according to the embodiment. In FIG. 7, a power supply voltage V is applied to a first magnetoresistive element 3a via a constant current source 21.
_DD is applied, the first magnetoresistive element 3a and the second magnetoresistive element 3b are connected in series, and the second magnetoresistive element 3a
One end of b is grounded.

First magnetoresistive element 3a of magnetoresistive element 3
And the second magnetoresistive element 3b are connected at a midpoint terminal a, and the voltage value at the midpoint terminal a is input to the non-inverting input terminal (+) of the comparator 25 as a sin wave sensor signal Vin. It has become so.

The resistance value of the first magnetoresistive element 3a (GMR1) and the resistance value of the second magnetoresistive element 3b (GMR2) change in opposite phases (the phase difference of the change in the resistance value is 180 °). FIG. 7 shows that the resistance values of GMR1 and GMR2 change in opposite phases by reversing the direction of the arrow (G
The arrow of MR1 points to the upper right and the arrow of GMR2 points to the lower left. ).

The threshold voltage Vth (reference voltage REF) for binarizing the sensor signal Vin input from the middle terminal a is applied to the inverting input terminal (-) of the comparator 25. The comparator 25 receives the input sensor signal Vin
Outputs an H level when the voltage value of the sensor signal Vin is larger than the threshold voltage Vth, and outputs an L level when the voltage value of the input sensor signal Vin is smaller than the threshold voltage Vth. It outputs the converted sensor pulse Vout.

Next, the operation of the magnetic detection device of the embodiment configured as described above will be described with reference to the drawings.

First, as shown in FIG. 6, the bias magnetic field H generated by the bias magnet 6 is applied to the first magnetoresistive element 3a.
And the multilayer film GMR of the second magnetoresistive element 3b
And go to gear 2.

At this time, the first magnetic resistance element 3a and the second magnetic resistance element 3b mounted on the support substrate 4 have a predetermined angle between the magnetic field H of the bias magnet 6 and the magnetic field H directed to the gear 2. At an angle θ (for example, 75 °).

For this reason, the magnetic field H of the bias magnet 6 is applied at a predetermined angle θ to each of the multilayer films GMR of the first magnetoresistive element 3a and the second magnetoresistive element 3b. Then, when the gear 2 rotates, as shown in FIG.
The magnetic field angle in the first magnetoresistive element 3a and the second magnetoresistive element 3b periodically changes by the deflection angle ± θ ′ with respect to the angle θ.

In this case, when the gear 2 rotates, the first magnetoresistive element 3a faces the convex portion 1a of the gear 2 and the second magnetoresistive element 3b faces the concave portion 1b. The magnetic field angle in the element 3a is θ + θ ′, and the magnetic field angle in the second magnetoresistive element 3b is θ−θ ′.

Next, when the gear 2 rotates, the first magnetoresistive element 3a faces the concave portion 1b of the gear 2 and the second magnetoresistive element 3b faces the convex portion 1a. The magnetic field angle in the element 3a is the angle θ−θ ′, and the magnetic field angle in the second magnetoresistive element 3b is the angle θ +
θ ′.

That is, the first magnetoresistance element 3a and the second
The magnetoresistive element 3b is defined by the convex portion 1a and the concave portion 1b of the gear 2.
Since the resistance values are arranged in accordance with the pitch, the resistance values greatly change in mutually opposite phases.

The direction of the bias magnetic field is periodically modulated by the rotation of the gear 2, and the first magnetic resistance element 3a
The change in the magnetic field strength of the second magnetoresistive element 3b is periodically modulated by the rotation of the gear 2. The periodic modulation is performed at a rate of one cycle for each movement of the convex portion 1a and the concave portion 1b of the tooth of the gear 2.

As described above, the resistance values of the first magnetoresistive element 3a and the second magnetoresistive element 3b change in opposite phases to each other, and the rate of change of the resistance value is more than twice as large as that of the conventional one. As shown in FIG. 7, a sinusoidal sensor signal having an amplitude that is at least twice as large as that of the conventional one is output from the midpoint terminal a of the first magnetoresistive element 3a and the second magnetoresistive element 3b. Vin is obtained, and the sensor signal Vin is sent to the comparator 25 of the sensor signal processing unit 5.

Further, since the sensor output can be obtained about twice or more as compared with the case of using the conventional Ni-Co based magnetoresistive element, the rotation detection of the gear 2 becomes very simple. That is, a highly sensitive magnetic detection device can be provided. In addition, since the change in the resistance value is large, the distance between the gear 2 and the magnetoresistive element 3 can be set to be, for example, twice as large as that in the related art, thereby simplifying the assembly.

Further, since the respective resistance values of the first magnetoresistive element 3a and the second magnetoresistive element 3b change in opposite phases, for example, only the resistance value of the first magnetoresistive element 3a changes. The rate of change of the resistance value is twice as high as that in the case of the above-described case.

Since the respective resistances of the first magnetoresistive element 3a and the second magnetoresistive element 3b change more than twice as compared with the prior art, the first magnetoresistive element 3a and the second magnetoresistive element 3b are different from each other. When the respective resistance values of the element 3b and the element 3b change in opposite phases, the overall rate of change in resistance changes by four times or more than the conventional one. Therefore, the sensitivity becomes higher than when only the resistance value of the first magnetoresistive element 3a is changed, and a simpler sensor signal processing unit can be provided.

Note that the predetermined angle θ is approximately 70 ° to approximately 80 °.
It is preferable to set to °. If the deflection angle due to the change in the magnetic field angle is about 10 °, the magnetic field angle is about 60 °.
This is because the angle changes within a range of about 90 °, and within this range, the rate of change in resistance is large, and a sensor signal with a larger amplitude can be obtained.

Next, the operation of the comparator 25 will be described. First, when the sensor signal Vin extracted from the connection point of the magnetoresistive elements 3a and 3b whose resistance values change in opposite phases to each other is input to the non-inverting input terminal of the comparator 25, the comparator 25 The voltage value of Vin is compared with the value of the threshold voltage Vth.

When the voltage value of the input sensor signal Vin is higher than the threshold voltage Vth, the comparator 25 outputs the H level, and when the voltage value of the input sensor signal Vin is equal to the value of the threshold voltage Vth. If it is smaller than the L level, the L level is output.

That is, the comparator 25 can binarize the sin-wave sensor signal Vin and output a sensor pulse Vout. The sensor pulse Vout is supplied to, for example, a counter provided at a subsequent stage, and the number of pulses is counted. Thereby, the rotation speed of the gear 2 can be detected based on the number of pulses within a certain time. Also, by using the first magnetoresistive element 3a and the second magnetoresistive element 3b having a large resistance change rate due to a change in the magnetic field angle, one comparator 25 allows the convex part 1 of the gear 2 to be used.
It is possible to obtain a binarized sensor pulse proportional to a and the concave portion 1b. That is, the rotation of the gear 2 can be detected by the simple sensor signal processing unit 5, and it is not necessary to use a conventional large-scale sensor signal processing unit.

The first magnetoresistive element 3a and the second magnetoresistive element 3b have the same temperature characteristic representing a change in resistance with respect to an external temperature change. That is, the respective resistance change rates of the first magnetoresistive element 3a and the second magnetoresistive element 3b have the same characteristics with respect to a temperature change. In other words, two magnetoresistive elements having the same value of the temperature coefficient representing the resistance change characteristic with respect to the temperature change are used.

For example, if the rate of change of resistance of the first magnetoresistive element 3a is + 2% with respect to temperature change, the rate of change of resistance of the second magnetoresistive element 3b is also + 2%. Therefore, the midpoint potential does not change even when the temperature changes. That is, a change in the midpoint potential due to a temperature change can be suppressed.

The present invention is not limited to the embodiment described above. In the embodiment, a half bridge configuration including the first magnetoresistive element 3a and the second magnetoresistive element 3b is used.

For example, a full bridge configuration in which two sets of the half bridge configuration are combined may be used. The use of the full-bridge magnetoresistive element further increases the sensitivity. Further, it is needless to say that the present invention can be variously modified and implemented without departing from the technical idea of the invention described in the embodiments.

[0073]

According to the first aspect of the present invention, the magnetic field of the bias magnet is applied to the first magnetoresistive element and the second magnetoresistive element having the multilayer film, and the magnetic field angle changes due to the movement of the detection target. Then, the resistance values of the first and second magneto-resistive elements greatly change in mutually opposite phases due to the magnetic field change.

That is, since the magnetoresistive means having a multilayer film having a large resistance change rate due to a change in the magnetic field angle is used, the change in the output value due to the change in the resistance value of the magnetoresistive means is several times larger than that of the conventional one. The rotation of the detection target can be detected by a simple sensor signal processing unit.

According to the second aspect of the present invention, in the sensor signal processing section, the comparing means determines the output value from the magnetoresistive means which causes a change in the resistance value due to a change in the magnetic field in accordance with the movement of the object to be detected. And compare the output value to 2
Since the output is made into a value, the rotation of the detection target can be detected by a simple sensor signal processing unit.

According to the third aspect of the present invention, the distance between the first magnetoresistive element and the second magnetoresistive element is set to be substantially the same as the distance between the convex portion and the concave portion of the rotation detecting body. The rotation of the body changes the resistances of the first and second magneto-resistive elements in opposite phases, so that the resistance between the first and second magneto-resistive elements is changed from the midpoint of the first and second magneto-resistive elements. A sensor signal having a large amplitude according to the motion of the detection target can be obtained.

According to the fourth aspect of the present invention, the magnetoresistive means is disposed so as to be inclined so that an angle between the magnetoresistive means and the direction of the magnetic field becomes a predetermined angle, so that a change in the resistance value due to a change in the magnetic field increases. .

According to the fifth aspect of the present invention, the predetermined angle is
By being in the angle range from approximately 70 ° to approximately 80 °,
The resistance value change due to the magnetic field change is further increased.

According to the sixth aspect of the present invention, the first thin film comprises:
Since the second thin film is a NiFeCo thin film and a Cu thin film, high sensitivity can be obtained.

According to the seventh aspect of the present invention, the resistance change rates of the first and second magnetoresistive elements change with the same characteristic with respect to a change in temperature. Since the potential does not change, it is possible to suppress a change in the midpoint potential due to a temperature change.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of a magnetic detection device according to the present invention.

FIG. 2 is a diagram showing a magnetoresistive element according to an embodiment.

FIG. 3 is a sectional view of a first magnetoresistive element and a second magnetoresistive element of the embodiment.

FIG. 4 is a configuration diagram for measuring a resistance value change rate when a constant current is applied to change a magnetic field angle.

FIG. 5 is a diagram showing a resistance change rate with respect to a magnetic field angle when the magnetic field angle is changed from 0 ° to 90 °.

FIG. 6 is a diagram illustrating a state in which a magnetic field of a bias magnet penetrating a first magnetoresistive element and a second magnetoresistive element is changed by rotation of a gear 2;

FIG. 7 is a circuit diagram of a sensor signal processing unit of the magnetic detection device according to the embodiment.

FIG. 8 is a side view of a conventional magnetic detection device.

FIG. 9 is a diagram showing an arrangement angle of a magnetoresistive element provided in a conventional magnetic detection device.

FIG. 10 is a configuration diagram of another example of the magnetic detection device and the magnetic detection signal processing device.

11 is a detailed circuit diagram of a sensor signal processing unit which is an example of the magnetic detection signal processing device shown in FIG.

12 is a diagram showing a change in a midpoint potential of a sensor signal extracted from the magnetic detection device shown in FIG.

[Explanation of symbols]

 1a convex portion 1b concave portion 2 gear 3 magnetic resistance element 3a first magnetic resistance element 3b second magnetic resistance element 4 support substrate 5 sensor signal processing section 6 bias magnet 7a, 7b electrode pattern 8a to 8c electrode 11 Fe film 13 NiFeCo Film 15 Cu film 21 Constant current source 25 Comparator

Claims (7)

[Claims] A bias magnet for generating a magnetic field toward a detection target having a magnetic material; a bias magnet disposed between the bias magnet and the detection target;
A half-bridge configuration in which a first magnetoresistive element and a second magnetoresistive element having a multilayer film in which at least a first thin film and a second thin film are alternately stacked a plurality of times are connected in series; Magnetoresistive means in which respective resistance values of the first magnetoresistive element and the second magnetoresistive element change in opposite phases to each other due to a change in the magnetic field applied to the multilayer film in accordance with a movement of a detection target; A sensor signal processing unit that outputs a change in an output value due to a change in the resistance value of the magnetic resistance unit as a motion detection output of the detection target, and the bias magnet, the magnetic resistance unit, and the sensor signal processing unit are integrally supported. A magnetic detection device, comprising: a support substrate. 2. The sensor signal processing section compares an output value from the magnetoresistive means, which generates a resistance change due to a change in a magnetic field according to the movement of the detection target, with a predetermined threshold value, 2. The magnetic detection device according to claim 1, further comprising a comparison unit that binarizes the output value and outputs the binarized value. 3. The object to be detected is a rotation detecting body in which convex portions and concave portions are alternately provided on a circumference, and the first magnetoresistive element and the second magnetoresistive element arranged on the support substrate are provided. 3. The magnetic detecting device according to claim 1, wherein a distance between the magnetoresistive elements is set to be substantially equal to a distance between the convex portion and the concave portion of the rotation detecting body. 4. The apparatus according to claim 1, wherein the magnetoresistive means is arranged so as to be inclined so that an angle between the magnetoresistive means and the direction of the magnetic field becomes a predetermined angle. The magnetic detection device according to claim 1. 5. The predetermined angle is approximately 70 ° to approximately 80 °.
5. The magnetic detecting device according to claim 4, wherein the angle is within an angle range up to °. 6. The magnetic detection device according to claim 1, wherein the first thin film is a NiFeCo thin film, and the second thin film is a Cu thin film. 7. The magnetic detection device according to claim 1, wherein the respective resistance change rates of the first and second magnetoresistive elements have the same characteristic with respect to a temperature change.