JPH1019601A - Magnetic detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the sensitivity to facilitate the detection of movement of an object for detection by providing a magnetoresistive element between first and second bias magnets, generating a magnetic field in the moving direc tion of the subject, and minimizing the reduction in magnetic field modulation to air gap of the subject and the magnetoresistive element. SOLUTION: A first bias magnet 25a and a second bias magnet 25b are arranged so that their polarities of bias magnetic field are mutually reversed, and magnetoresistive elements 16a1 , 16a2 are arranged on the surface substantially perpendicular to the moving direction of an object for detection between the magnets 25a, 25b. A bias magnetic field is generated in the moving direction of the subject in the space between the magnets 25a, 25b. The magnetoresistive elements 16a1 , 16a2 are changed in resistance by the state change of bias magnetic field according to the movement of the subject. The reduction in magnetic field modulation to air gap of the subject and the magnetoresistive elements 16a1 , 16a2 is relatively minimized.

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 magnetic sensor has a bias magnet and detects movement, rotation, and the like of a detection target made of a magnetic material by using a resistance change of a magnetoresistive effect element. , Widely used.

As a known technique of this type of conventional magnetic sensor, there is, for example, one disclosed in Japanese Patent Application Laid-Open No. 3-195970.

FIG. 9 shows a first system of the magnetic sensor described in Japanese Patent Application Laid-Open No. 3-195970. The magnetic sensor shown in FIG. 9 includes a gear 11 as a detection target made of a magnetic material.
Magnet 15 that generates a bias magnetic field 13 toward
Is provided.

An insulating substrate 17a on which a magnetoresistive element 16a is formed is disposed on a plane perpendicular to the direction of the bias magnetic field 13.

The magnetic field lines of the bias magnetic field generated from the bias magnet 15 are periodically modulated by peaks and valleys of the gear 11,
It changes sinusoidally according to the relative positions of the teeth of the gear 11.

The deflection angle θ of the bias magnetic field 13
It changes with the movement of 1. The change of the magnetic field strength in the deflection angle direction generated in the plane of the magnetoresistive element 16a due to the change of the magnetic field angle is detected as the resistance change of the magnetoresistive element 16a, and the movement of the gear 11 is detected.

FIG. 10 shows a second type of magnetic sensor described in Japanese Patent Application Laid-Open No. 3-195970. As shown in FIG. 10, the magnetoresistive element 16b provided on the insulating substrate 17b is disposed on a surface having two directions of the bias magnetic field direction 13 and the movement direction of the gear 11.

This method utilizes the fact that the angle between the direction of the magnetic field due to the fluctuation of the magnetic field and the direction of the current flowing through the magnetoresistive element 16b changes. Accordingly, the resistance of the magnetoresistive element 16b changes.

As described above, even in the first and second systems of the magnetic sensor described above, the direction of the bias magnetic field 13 is in the direction toward the gear 11, and the bias magnetic field 13 is biased in accordance with the movement of the gear 11. The fact that the direction of the magnetic field 13 swings in the movement direction of the gear 11 is used.

[0011]

However, in the configuration of the conventional magnetic sensor, as the air gap between the gear 11 and the magnetoresistive elements 16a and 16b increases, the deflection angle sharply decreases. Become.

Although the deflection angle depends on the shape of the bias magnet 15 and the shape of the gear 11, the maximum detectable air gap is about 2 mm to 3 mm. For this reason, there has been a demand for a magnetic detection device capable of improving the sensitivity by increasing the detection gap and easily detecting the movement of the gear 11.

It is an object of the present invention to provide a magnetic detection device which can increase the detection gap to improve the sensitivity and can easily detect the motion of the detection target.

[0014]

The present invention employs the following means in order to solve the above-mentioned problems. The first aspect of the present invention is a first magnetic field generation unit that generates a bias magnetic field toward a detection target having a magnetic material, and a bias magnetic field that generates a bias magnetic field toward the detection target having the magnetic material. And a second magnetic field generator is disposed in the direction of movement of the object to be detected in such a manner as to face the magnetic field generating section, and the polarity of the bias magnetic field is opposite to the polarity of the bias magnetic field generated by the first magnetic field generating section. A magnetic field generating section, and a bias magnetic field between the first magnetic field generating section and the second magnetic field generating section, which is installed on a plane substantially perpendicular to the movement direction of the detection target; A gist comprises a magnetoresistive effect element that generates a resistance change by a change in the state of the bias magnetic field according to the movement of the detection target.

According to the present invention, the second magnetic field generator is opposed to the first magnetic field generator so that the polarity of the bias magnetic field is opposite to the polarity of the bias magnetic field of the first magnetic field generator. The magneto-resistance effect element is arranged in a bias magnetic field between the first magnetic field generation unit and the second magnetic field generation unit, and the magneto-resistance effect element is arranged in the motion direction of the detection target. Because it was installed on a surface that is almost perpendicular to the direction of movement,
In the space between the first magnetic field generation unit and the second magnetic field generation unit, a bias magnetic field is generated in the movement direction of the detection target.
The bias magnetic field is modulated such that a bias magnetic field in the movement direction of the detection target moves toward the detection target.

For this reason, the magnetoresistive effect element causes a change in resistance due to a change in the state of the bias magnetic field in accordance with the movement of the object to be detected.

As described above, the magnetoresistive effect element is provided between the first magnetic field generating section and the second magnetic field generating section, and the magnetic field is generated in the direction of movement of the detection target, so that the detection target and the magnetic field are generated. The reduction in the amount of magnetic field modulation with respect to the air gap with the resistance effect element is relatively small.

As a result, the sensitivity to the air gap is improved, and the motion of the detection target can be easily detected.

In the invention of claim 2, the gist is that the magnetoresistance effect element is arranged near the magnetic pole surface of the first magnetic field generating section or the second magnetic field generating section on the side to be detected. I do.

According to the present invention, the magnitude of the modulation of the bias magnetic field becomes maximum near the magnetic pole surface on the detection target side of the first magnetic field generating unit or the second magnetic field generating unit.
By arranging the magnetoresistive element at this position, a large change in resistance can be obtained.

[0021] In the invention of claim 3, the gist is that the magnetoresistive element is mounted on an insulating substrate, and further, other electronic components are mounted on the insulating substrate.

That is, since an insulating substrate having a magnetoresistive element can be inserted between the first magnetic field generating unit and the second magnetic field generating unit, a plurality of electronic components can be mounted on the insulating substrate.

[0023]

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 perspective view of Embodiment 1 of the magnetic detection device of the present invention. FIG. 2 is a cross-sectional view of Embodiment 1 of the magnetic detection device of the present invention.

<Embodiment 1> The magnetic detection device shown in FIG. 1 is a magnetic sensor, and has a gear 11 as a detection target that performs a rotational movement.

Immediately below the gear 11, a first bias magnet 25a as a first magnetic field generator, a second bias magnet 25b as a second magnetic field generator, and a magnetoresistive element 1
An insulating substrate 17a having 6a1 and 16a2 is provided.

The insulating substrate 17a has an integrated circuit (I
C) A plurality of electronic components such as 19, a resistor and a capacitor 21 are mounted. That is, the first bias magnet 2
Since the insulating substrate 17a having the magnetoresistive elements 16a1 and 16a2 can be inserted between 5a and the second bias magnet 25b, a plurality of electronic components can be mounted on the insulating substrate 17a.

The first bias magnet 25a generates a bias magnetic field toward the gear 11 having a magnetic material, and has an N pole on the gear 11 side.

The second bias magnet 25b is arranged in the movement direction of the gear 11 to face the first bias magnet 25a, and generates a bias magnetic field toward the gear 11 having the magnetic material. An S pole is arranged on the side.

The magnetoresistive element 16a1 is arranged in a vertical direction, and the magnetoresistive element 16a2 is arranged in a direction perpendicular to the vertical direction.

The magnetoresistive elements 16a1 and 16a2 are
The resistance changes depending on the angle between the direction of the current flowing through the magnetoresistive element and the direction of the magnetic field, and the magnetic field strength. FIG. 2 shows how the resistance changes with respect to the magnetic field.

The angle between the direction of the current and the direction of the magnetic field is 90
゜, that is, the magnetoresistive effect element 16a2
The resistance changes according to the magnitude of the magnetic field strength, as shown in FIG.

When the angle between the direction of the current and the direction of the magnetic field is 0 °, that is, the magnetoresistive element 16a1
The resistance does not change regardless of the strength of the magnetic field.

Since the output of the magnetoresistive element 16a1 cannot be obtained, it is used for temperature correction. Here, since the resistance of only the magnetoresistive element 16a2 changes, its output is used.

The magnetoresistive elements 16a1 and 16a2 are
First bias magnet 25a and second bias magnet 25b
The bias magnetic field is provided in a plane perpendicular to the direction of movement of the gear 11, and a resistance change is caused by a state change of the bias magnetic field according to the movement of the gear 11.

When the gear 11 rotates, the positional relationship between the gear 11 and the magnetoresistive elements 16a1 and 16a2 is as follows.
There is a positional relationship shown in FIG. 3 and a positional relationship shown in FIG.

In FIG. 3, the N of the first bias magnet 25a is
This is a case where the pole and the peak of the gear 11 are arranged to face each other, and the S pole of the second bias magnet 25b and the mountain next to the gear 11 are arranged to face each other.

In FIG. 4, the N of the first bias magnet 25a is
Gear 11 between the pole and the south pole of the second bias magnet 25b.
This is the case where the mountains are arranged.

In the positional relationships shown in FIGS. 3 and 4, the magnitudes H1 and H2 of the magnetic field in the direction toward the gear 11 at the point A of the magnetoresistive effect element are such that H1 is larger than H2. This signal produces a sine wave output.

The magnetoresistive elements 16a1 and 16a2 are
The bias magnet 25a is arranged near the magnetic pole surface on the gear 11 side and at a position shifted from the center between the magnets.

According to the magnetic detecting device thus configured, as shown in FIG. 3, the N of the first bias magnet 25a is
The bias magnetic field generated from the pole is the first bias magnet 2
5a and the S of the second bias magnet 25b.
There is a route to enter the pole.

In any of the paths, the gear 1
The movement of one modulates its path. The bias magnetic field between the first bias magnet 25a and the second bias magnet 25b on the gear 11 side and near the magnetic pole surface is the gear 1
1 movement direction, that is, N of the first bias magnet 25a.
The direction is from the pole to the south pole of the second bias magnet 25b.

The bias magnetic field oscillates in the direction toward the gear 11 due to the movement of the gear 11. That is, when the gear 11 moves, the bias magnetic field component in the direction toward the gear 11 changes. Therefore, the resistance of the magnetoresistive element 16a2 changes due to a change in the state of the bias magnetic field according to the movement of the gear 11.

In the state shown in FIG. 4, most of the bias magnetic field is transmitted from the N pole of the first bias magnet 25a to the gear 1
1 and the gear 11 from the S pole of the second bias magnet 25b.

In this bias magnetic field, the magnetoresistive element 1
6a2, the bias magnetic field shown in FIG. 4 passing through the magnetoresistive element 16a2 is larger than the bias magnetic field shown in FIG.

Further, by shifting the magnetoresistive effect element 16a2 from the center between the first bias magnet 25a and the second bias magnet 25b, the bias magnetic field swing becomes large.

FIG. 5 shows a simulation result of the fluctuation of the magnetic field between the two bias magnets. In the figure, the portion indicated by the thick line is the magnetic field swing when the two bias magnets 25a and 25b and the peak of the gear 11 are arranged to face each other as shown in FIG.

The portion shown by the thin line is, as shown in FIG.
This is the fluctuation of the magnetic field when the peak of the gear 11 is arranged between the two bias magnets 25a and 25b.

As can be seen from the simulation result of the magnetic field swing shown in FIG. 5, the magnetic field swing in the positional relationship shown in FIG. 4 is larger than the magnetic field swing in the positional relationship shown in FIG.

Further, it can be seen that the bias magnetic field fluctuation increases when the magnetoresistive effect element 16a2 is disposed on the magnetic pole surface side of the first bias magnet 25a or the magnetic pole surface side of the second bias magnet 25b.

As described above, the magnetoresistive element 1 is placed between the first bias magnet 25a and the second bias magnet 25b.
By providing a bias magnetic field in the direction of the gear 11, the decrease in the amount of magnetic field modulation with respect to the air gap becomes relatively small, so that the change state of the magnetic field can be detected even if the air gap is relatively large.

As a result, the air gap is enlarged, the sensitivity is improved, and the movement of the gear 11 can be easily detected.

FIGS. 3 and 4 show the magnetoresistive element 16a.
2 shows a deflection angle θ at a point A. FIG. 6 shows the result of simulating the relationship between the deflection angle θ and the air gap,
In the case of the first embodiment (Q in the figure) and the conventional case (P in the figure)
Are shown for each.

As can be seen from FIG. 6, in the first embodiment, even if the air gap becomes large, the decrease in the deflection angle θ is smaller than that in the conventional case. The difference between the structure of the first embodiment and the structure of the conventional case is as described above.

As described above, in the first embodiment, the air gap can be increased, and as a result, the sensitivity is improved and the movement of the gear 11 can be easily detected.

<Second Embodiment> Next, a second embodiment of the magnetic detection device of the present invention will be described. FIG. 7 shows the configuration of the magnetic detection device according to the second embodiment of the present invention.

In the second embodiment, the magnetoresistance effect element 16
a1, 16a2, the magnetoresistive element 16a
A first magnet 3 having an N pole magnetized on the side facing 1,16a2
5a are provided, and the magnetoresistive elements 16a1, 16a2
The magnetoresistive elements 16a1 and 16a
A second magnet 35b having an S pole magnetized is provided on the side facing 2.

The magnetoresistive elements 16a1 and 16a2 are
The gear 11 is disposed on a plane perpendicular to the movement direction of the gear 11 and the gear 1
It is arranged on the gear side of the magnet center position in the direction toward 1 (point A in FIG. 8).

The other structure is the same as that of the first embodiment, and the same parts are denoted by the same reference numerals and will be described.

In the second embodiment configured as described above, as shown in FIG.
a path from the north pole to the south pole of a, the N of the second magnet 35b
A path from the pole to the S pole and a path from the N pole of the first magnet 35a to the S pole of the second magnet 35b are formed.

That is, at the position where the magnetoresistive element is disposed in the space between the first magnet 35a and the second magnet 35b, the bias magnetic field generated by the first magnet 35a is:
It enters the second magnet 35b. As a result, a magnetic field is generated in the movement direction of the gear 11.

The bias magnetic field oscillates in the direction toward the gear 11 according to the movement of the gear 11. That is,
The intensity of the magnetic field component in the direction toward the gear 11 changes.

For this reason, the magnetoresistive effect element 16a2
A resistance change is caused by a change in the state of the bias magnetic field according to the movement of the gear 11.

As described above, the magnetoresistive elements 16a1 and 16a2 are provided between the first magnet 35a and the second magnet 35b.
By generating a magnetic field in the movement direction of the gear 11, the decrease in the amount of magnetic field modulation with respect to the air gap between the gear 11 and the magnetoresistive elements 16a1 and 16a2 is relatively small, and even if the air gap is relatively large. , The change state of the magnetic field can be detected.

As a result, the sensitivity to the air gap is improved, and the movement of the gear 11 can be easily detected.

A plurality of electronic components such as an IC 19, a resistor and a capacitor 21 are mounted on the insulating substrate 17a. That is, the first magnet 35a and the second magnet 35
b, the insulating substrate 17a having the magnetoresistive elements 16a1 and 16a2 can be inserted.
A plurality of electronic components can be mounted on 7a.

The present invention is not limited to the first and second embodiments. In the first and second embodiments, the magnetoresistive element 16 is provided on the insulating substrate 17a.
Although a1 and 16a2 are provided, for example, only the magnetoresistive element 16a2 may be provided on the insulating substrate 17a.

In the first and second embodiments, a half bridge composed of the magnetoresistive element 16a1 in the vertical direction and the magnetoresistive element 16a2 in the horizontal direction is used. For example, a longitudinal magnetoresistive element 16a1 and a lateral magnetoresistive element 16a2 are arranged, and a lateral magnetoresistive element 16a2 is arranged below the longitudinal magnetoresistive element 16a1, and Alternatively, a full bridge in which the vertical magnetoresistive element 16a1 is arranged below the horizontal magnetoresistive element 16a2 may be used.

[0068]

According to the present invention, the second magnetic field generator is opposed to the first magnetic field generator so that the polarity of the bias magnetic field is opposite to that of the bias magnetic field of the first magnetic field generator. And the magnetoresistive element is arranged in a bias magnetic field between the first magnetic field generating section and the second magnetic field generating section, and the magnetoresistive element is detected. Since it was installed on a surface that is almost perpendicular to the direction of movement of the subject,
In the space between the first magnetic field generation unit and the second magnetic field generation unit, a bias magnetic field is generated in the movement direction of the detection target.
The bias magnetic field changes according to the movement of the detection target.

For this reason, in the magnetoresistive effect element, a resistance change is caused by a change in the state of the bias magnetic field according to the movement of the detection target.

As described above, the magnetoresistive effect element is provided between the first magnetic field generating section and the second magnetic field generating section, and the magnetic field is generated in the direction of movement of the detection target. The reduction in the amount of magnetic field modulation with respect to the air gap with the resistance effect element is relatively small.

As a result, the sensitivity to the air gap is improved, and the motion of the detection target can be easily detected.

Further, the magnetoresistive effect element is placed near the magnetic pole surface on the detection target side of the first magnetic field generation section or the second magnetic field generation section where the change of the bias magnetic field due to the movement of the detection target increases. The arrangement causes the magnetoresistive effect element to undergo a large resistance change according to the movement of the detection target.

Further, since an insulating substrate having a magnetoresistive element can be inserted between the first magnetic field generating unit and the second magnetic field generating unit, a plurality of electronic components can be mounted on the insulating substrate.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a magnetic detection device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a change in resistance of a magnetoresistive element with respect to a magnetic field.

FIG. 3 is a side view of the magnetic detection device when two adjacent peaks and two bias magnets of the gear are arranged to face each other.

FIG. 4 is a side view of the magnetic detection device when one peak of the gear is disposed between two bias magnets.

FIG. 5 is a diagram illustrating a simulation result of a magnetic field swing between two bias magnets.

FIG. 6 is a diagram showing a comparison between the conventional technology and the present invention regarding the relationship between the air gap and the deflection angle.

FIG. 7 is a perspective view showing a second embodiment of the magnetic detection device of the present invention.

FIG. 8 is a side view showing a magnetic detection device according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of a conventional magnetic detection device.

FIG. 10 is a diagram showing another example of the conventional magnetic detection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Gear 13 Magnetic field direction 15 Bias magnet 16a, 16b, 16a1, 16a2 Magnetoresistive element 17a, 17b Insulating substrate 19 IC 21 Resistance / capacitor 25a First bias magnet 25b Second bias magnet 35a First magnet 35b Second Magnet

Claims (3)

[Claims] A first magnetic field generating unit that generates a bias magnetic field toward a detection target having a magnetic material; and a first magnetic field that generates a bias magnetic field toward the detection target including the magnetic material. It is arranged in the direction of movement of the detection target so as to face the generation unit, and the polarity of the bias magnetic field is the first direction.
A second magnetic field generator arranged in a direction opposite to the polarity of the bias magnetic field generated by the first magnetic field generator, and a bias between the first magnetic field generator and the second magnetic field generator. A magnetoresistance effect element that is installed on a surface that is in a magnetic field and that is substantially perpendicular to the direction of movement of the detection target, and that causes a resistance change due to a state change of the bias magnetic field according to the movement of the detection target. A magnetic detection device characterized by the above-mentioned. 2. The device according to claim 1, wherein the magnetoresistive element is arranged near a magnetic pole surface on the detection target side of the first magnetic field generating unit or the second magnetic field generating unit.
3. The magnetic detection device according to claim 1. 3. The magnetic detection device according to claim 1, wherein the magnetoresistive element is mounted on an insulating substrate, and another electronic component is mounted on the insulating substrate. apparatus.