JPH0410570B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an improvement in a position sensor using a magnetoresistive element. In particular, magnetoresistive elements (or a group of several magnetoresistive elements connected in series) arranged in series at a certain distance in a region that intersects a magnetic field moving in a particular direction. are connected in series to form a series circuit, and this series circuit includes a first magnetoresistive circuit having a structure having an intermediate terminal, and a corresponding magnetoresistive circuit having the same structure as the first magnetoresistive circuit ( or a group of several magnetoresistive elements connected in series) is a second magnetoresistive circuit that is arranged shifted by 1/2 of the above-mentioned specific distance in the moving direction of the above-mentioned moving alternating magnetic field. Therefore, each of these two magnetoresistive circuits has
Sine waves with a phase difference of 90° are applied, and these two sine waves are divided by the above-mentioned series-connected magnetoresistive circuit, and the two AC voltages obtained from the intermediate terminal are used. The basic principle of the position sensor is to measure the frequency of the above-mentioned moving alternating magnetic field and detect the position and movement status of the moving object that generates the moving alternating magnetic field. Regarding improvements.

(2) Background of the technology There are materials such as indium antimonide (InSb) and indium arsenide (InAs) that change their resistance in response to the strength of intersecting magnetic fields, and are called magnetoresistive materials. An element made of such a magnetoresistive material (hereinafter referred to as a magnetoresistive element) is placed in a magnetic field, and a geometric shape that gives a regular change to the reluctance of a magnetic path that intersects the magnetoresistive element. When an object having . be able to.

(3) Prior art and problems A position sensor using a magnetoresistive element based on this basic principle can be realized using a single magnetoresistive element, but as shown in Figs. To,
Two magnetoresistive elements 1a and 1b are connected in series and a voltage is applied between the two terminals 11 and 12 of this series circuit. The two magnetic resistors 1
A moving body (magnetic body 24, etc. having slits 23, 23', etc. or magnetic body 2, etc. having unevenness) that regularly changes reluctance in contact with a and 1b is moved in the direction of arrow A in the figure. As a result, an alternating magnetic field moving in the direction of arrow A is generated, and the voltage applied between the terminals 11 and 12 has a magnetic resistance with the same period as the moving alternating magnetic field. The voltage is divided by the bodies 1a and 1b and output from the intermediate terminal 13. Therefore,
By measuring the frequency of the voltage obtained from this intermediate terminal 13, the moving state of the above-mentioned moving body (24 etc. or 2 etc.), which is the cause of the change in reluctance that changes the resistance of the magnetoresistive elements 1a and 1b, can be detected. It will be possible.

By the way, since it is desirable that the voltage of this intermediate terminal 13 is high to some extent, the magnetic resistors 1a, 1
It is advantageous to use a group of magnetoresistive elements that have the same relative positional relationship between b and the slits and irregularities of the moving body, and according to this idea, as shown in Figs. This is generally the case. That is, 1a, 1b, 1a', 1b' are each a series circuit of two magnetoresistive elements, and
1a and 1a', and 1b and 1b' are series circuits of magnetoresistive bodies each having the same resistance change. In addition,
There is no reason why the number of magnetoresistive elements constituting each group of magnetoresistive elements is limited to two, and it goes without saying that an appropriate number such as three or four may be selected.

Furthermore, as shown in Figures 5 and 6, the two sets of position sensors described above are arranged at positions that differ by 90 degrees in electrical angle from each other, and two alternating current voltages having phases that differ by 90 degrees from each other can be obtained. It is clear from the equation below that the position detection accuracy is improved and the direction of rotation can be easily identified.

A cos θ sin ωt + Asin θ cos ωt = B sin (ω t + θ) where θ is the electrical angular position to be detected, and ω is the electrical angular velocity of the AC voltage applied to the terminals 11 and 12 of the series circuit.

In FIG. 5, magnetoresistive elements 1a, 1a' and 1
The pair of magnetoresistive elements 1c, 1c' and 1d, 1d' constitute a first magnetoresistive circuit by being in contact with the slit 23 etc. and the magnetic material portion 24 without a slit. The pair with magnetic material part 24 and slit 2
3', 23'' and the boundary between the slits 23, 23' and the magnetic material portion 24 constitute a second magnetoresistive circuit, and these two magnetoresistive circuits are arranged at a distance of 90° from each other. °The electrical angle position is shifted.On the other hand,
In FIG. 6, magnetoresistive elements 1a, 1a' and 1
The pair of magnetoresistive elements 1c, 1c' and 1d, 1d' is in contact with the protrusion 21 etc. and the recess 22 etc. to form a first magnetoresistive circuit. 2
1, 21' and the recesses 22', 22'' and the recess 2
A second magnetoresistive circuit is formed in contact with the boundary between the projections 2 and 22' and the protrusions 21 and 21', and these two magnetoresistive circuits are electrically angularly shifted from each other by 90 degrees.

Then, the terminals 11 and 15 are connected, and a cosine wave is applied between the terminals 12 and 11, that is, the first magnetoresistive circuit, and a cosine wave is applied between the terminals 15 and 14, that is, the second magnetoresistive circuit. A sine wave is applied to the terminals 13 and 16, and a divided position signal voltage is obtained between the terminals 13 and 16.

By the way, the above two magnetoresistive circuits are generally formed on the same ferromagnetic plate,
The width of each magnetoresistive element 1a, 1b, etc. is 0.1 to 0.2 mm.
It is a film of indium antimonide (InSb) or the like with a length of about 1 mm, and each magnetoresistive element 1a,
The conductive path 5 that connects 1b, etc. is a copper film with a width of about 0.3 mm and a thickness of several microns, and the two magnetoresistive circuits can be formed extremely close to each other with a distance of about 0.05 mm. Generally speaking, the capacitance between two magnetoresistive circuits is quite large, and with this capacitance, it is difficult to prevent the two magnetoresistive circuits from capacitively coupling and interfering with each other. This has the disadvantage of reducing detection accuracy.

(4) Purpose of the Invention The purpose of the present invention is to eliminate this drawback, and the purpose of the present invention is to solve this problem by using a magnetic field that is arranged at a certain distance and connected in series in a region that intersects a magnetic field moving in a certain direction. A first magnetoresistive member having a structure in which a pair or more of resistors (or a group of several magnetoresistive members connected in series) are connected in series to form a series circuit, and this series circuit has an intermediate terminal. A circuit and a corresponding magnetoresistive element (or a group of several magnetoresistive elements connected in series), each having the same structure, move along the above specified distance in the direction of movement of the above-mentioned moving alternating magnetic field. The second
A sine wave with a phase difference of 90° is applied to each of these two magnetoresistive circuits, and these two sine waves are connected to the magnetoresistive circuit connected in series. Using two alternating voltages divided by a circuit and obtained from an intermediate terminal, the frequency of the above-mentioned moving alternating magnetic field is measured, and the position and moving state of the moving object that generates this moving alternating magnetic field is measured. In a position sensor using a magnetic resistor whose basic principle is to detect
A position sensor using a magnetoresistive element that prevents electrostatic induction from occurring between the first magnetoresistive circuit and the second magnetoresistive circuit and improves detection accuracy. It is about providing.

(5) Structure of the Invention The structure of the present invention consists of (a) magnetoresistive elements (or (a) a first magnetoresistive circuit having an intermediate terminal as well as an input/output terminal; (b) the first magnetoresistive circuit; Although having the same geometrical structure, each magnetoresistive element has a direction of movement of the moving alternating magnetic field with respect to a respective one of the magnetoresistive elements constituting the first magnetoresistive element circuit. (c) the first magnetoresistive circuit and the second magnetoresistive circuit each have a , a sine wave with a phase difference of 90° is applied,
measuring the alternating current voltage obtained from each of the intermediate terminals to detect the frequency of the alternating magnetic field;
In a position sensor using a magnetoresistive element,
(d) A position sensor using a magnetoresistive element is characterized in that the first magnetoresistive circuit and the second magnetoresistive circuit are electrostatically shielded from each other.

Although the idea of the present invention itself is a generally known technical idea, since the two magnetoresistive circuits have unique shapes and structures as described above, it is not always possible to realize the desired electrostatic shielding. It's not easy.

The present invention has completed the following two methods as a means for exhibiting a significantly superior electrostatic shielding effect in a position sensor using a magnetoresistive circuit having such specific conditions.

As shown in FIGS. 7 and 8, the first means (means according to claim 2) includes a magnetoresistive element including a first magnetoresistive circuit and a second magnetoresistive circuit. A thin film of a magnetoresistive material such as indium antimonide (InSb) is formed on the same plate-shaped magnetic material (ferrite plate, etc.), and the conductor connecting the magnetoresistive members is made of copper. In the step of forming a film or the like, a linear conductor such as a copper film is formed in the region sandwiched between the two circuits. FIG. 7 shows a magnetoresistive element 8 which is the gist of this first means (means according to claim 2).
, and FIG. 8 is a cross-sectional view taken along the line B-B. 3 is a plate-shaped magnetic material, 1a, 1b, etc. are magnetoresistive materials, 5 is a conductor, and 7 is a It is an electrostatic shield, and 9 is an adhesive for bonding the magnetic resistors 1a, 1b, etc. to the surface of the magnetic plate 3. The results of an experiment conducted to confirm the effect showed that there was no mutual interference.
It has been confirmed that the amount decreases by about 15-20%.

The magnetoresistive element 8' in the second means (means according to claim 3) has a first magnetoresistive circuit and a second magnetoresistive element, as its cross-sectional view is shown in FIG. The magnetoresistive material for the circuit is formed on the same plate-shaped ferromagnetic material (ferrite plate, etc.) with a thin film of magnetoresistive material such as indium antimonide (InSb), and the magnetoresistive material for the above two circuits is Either form a conductor layer through an insulator layer and ground it, or place it at a position facing the above two magnetoresistive circuits, slightly isolated from them through a space. Either support the conductive layer and ground it, or form a conductive layer on the back of the magnetic plate and ground it, or connect both of these two conductive layers. Both should be formed and both should be grounded.

In the figure, numerals 10 and 11 are conductor ground layers. However, it is desirable that the material of the conductive ground layers 10 and 11 is a non-magnetic material, and it is essential that the material of the conductive ground layer 10 formed on the upper surface of the magnetoresistive circuit is a non-magnetic material.

The results of experiments conducted to confirm the effect have confirmed that mutual interference is reduced by about 35 to 45%.

(6) Embodiments of the Invention Hereinafter, a position sensor using a magnetoresistive element according to an embodiment of the present invention will be further described with reference to the drawings.

() Refer to Figure 10, an embodiment of claim 2, which is limited by claim 6. In the figure, 4 is a permanent magnet, which forms a parallel magnetic field H of approximately 1 kilogauss. . 3 is a plate-shaped magnetic body made of a ferromagnetic material such as ferrite, and in this example, the height is several mm, the width is several mm, and the thickness is about 0.5 mm.

1d is a magnetoresistive material made of indium antimonide (InSb) and has a thickness of about 5 μm.
Its width is 0.3 mm, its length is about 1 mm, and its height is about 1.5 mm. The width of the conductive path 5 and electrostatic shield 7 formed with a copper film is 0.3 mm.
That's about it. The magnetoresistive elements 1a, 1b, etc., the electrostatic shield 7, and the conductive path 5 can be formed by a combination of a photolithography method, an ion plating method, a sputtering method, a vacuum evaporation method, etc., and an adhesive method using an adhesive. can be easily formed.

It goes without saying that the structure of this magnetoresistive element 8 is as shown in FIGS. 7 and 8. 24
1 is a cylindrical member having a slit 231;
It rotates around the axis 6, and the magnetic resistance elements 1a and 1b
etc., with a distance of approximately 0.3 mm.

When terminals 11, 15, and 17 of a position sensor made using a magnetic resistor with the above structure are grounded as a common terminal, and a cosine wave of about 5V is applied between terminals 12 and 11, electrostatic induction causes terminal 13,
Although it is unavoidable that a certain amount of voltage is generated not only between 11 but also between 15 and 16, the level of voltage is 0.3 mV, which is about 15 to 20% lower than in the prior art.

() Refer to Figure 11 of the embodiment described in claim 3, which is limited by claim 5. In the figure, 4 is a permanent magnet, which forms a parallel magnetic field H of approximately 1 kilogauss. do. 3 is a plate-shaped magnetic body made of a ferromagnetic material such as ferrite, and in this example, the height is several mm, the width is several mm, and the thickness is about 0.5 mm.

1d is a magnetoresistive material made of indium antimonide (InSb) and has a thickness of about 5 μm.
Its width is 0.3 mm, its length is about 1 mm, and its height is about 1.5 mm. The width of the conductive path 5 formed with a copper film is about 0.3 mm, and the electrostatic shields 10 and 11 are phosphor bronze plates with a thickness of about 0.1 mm. The thickness of the adhesive is about 0.1 mm. Magnetoresistive elements 1a and 1b, electrostatic shields 10 and 11, and conductive path 5
It can be easily formed by a combination of a photolithography method, an ion plating method, a sputtering method, a vacuum evaporation method, etc., and an adhesive method using an adhesive.

It goes without saying that the structure of this magnetoresistive element 8' is as shown in FIG.

2 is a rod-shaped member having regular unevenness 21, 22, etc., and moves in the direction of arrow A. The magnetoresistive elements 1a, 1b, etc. are arranged at a distance of about 0.3 mm.

When the electrostatic shields 10 and 11 of the position sensor made using the magnetic resistor with the above structure are grounded and a cosine wave of about 5V is applied between the terminals 11 and 15,
Although it is unavoidable that some voltage is generated not only between terminals 13 and 11 but also between terminals 15 and 16 due to electrostatic induction, the level is about 0.1 mV, which is about 35 to 45% lower than in the conventional technology. .

(7) Effects of the Invention As explained above, according to the present invention, magnetoresistive elements (or A group of several magnetoresistive elements connected in series) are connected in series to form a series circuit, and this series circuit includes a first magnetoresistive element circuit having a structure having an intermediate terminal; Each magnetoresistive element (or a group of several magnetoresistive elements connected in series), which has the same structure as , moves in the direction of movement of the above-mentioned moving alternating magnetic field by 1/2 of the above-mentioned specific distance. A sine wave having a phase difference of 90° is applied to each of these two magnetoresistive circuits, and these two sine waves The frequency of the above-mentioned moving alternating magnetic field is measured by using the two alternating current voltages obtained from the intermediate terminal after being divided by the magnetoresistive circuit connected in series, and this moving alternating magnetic field is generated. In a position sensor using a magnetoresistive element whose basic principle is to detect the position and movement state of a moving object, there is a wire between the first magnetoresistive circuit and the second magnetoresistive circuit. It is possible to provide a position sensor using a magnetoresistive element that prevents electrostatic induction from occurring and has improved detection accuracy.

[Brief explanation of drawings]

1 to 6 are conceptual configuration diagrams of a position sensor using a magnetoresistive element in the prior art. 7 and 8 are a plan view and a cross-sectional view taken along line B--B of a magnetoresistive element according to the gist of a position sensor using a magnetoresistive member according to claim 2, respectively. FIG. 9 is a sectional view of a magnetoresistive element according to the gist of a position sensor using a magnetoresistive member according to claim 3. Figure 10,
FIG. 11 is a conceptual configuration diagram of a position sensor using a magnetic resistor according to an embodiment of the present invention. 1a, 1a', 1b, 1b', 1c, 1c', 1d,
1d'... Magnetic resistance element, 11, 12, 14, 15... Main terminal, 13, 16... Intermediate terminal, 17... Ground terminal,
2, 24... Rod-shaped member, 241... Cylindrical member, 2
1, 21'...protrusion, 22, 22'...recess, 23, 2
3', 231...Slit, 3...Plate magnetic material, 4...
Permanent magnet, 5... Conductive member, 6... Axis of rotating body, 7,
10, 11... Electrostatic shield, 8, 8'... Magnetoresistive element, 9... Adhesive, A... Direction of movement of object, H... Direction of magnetic field, E... Made using magnetoresistive element according to prior art. Voltage waveform obtained from the intermediate terminal of the position sensor.

Claims (1)

[Claims] 1. (a) Magnetoresistive elements (or a group of magnetoresistive elements) arranged in a region that can intersect an alternating magnetic field moving in a specific direction at a specific distance and connected to each other in series. The series circuit consists of a series circuit having one or more pairs of input/output terminals as well as a first terminal having an intermediate terminal.
and (b) having the same geometrical structure as the first magnetoresistive circuit, but each magnetoresistive member is a magnetoresistive member of each of the magnetoresistive members constituting the first magnetoresistive circuit. For the corresponding magnetoresistive element,
a second magnetoresistive circuit disposed offset by 1/2 of the specific distance in the moving direction of the moving alternating magnetic field, (c) the first magnetoresistive circuit and the A sine wave having a phase difference of 90° from each other is applied to each of the second magnetoresistive circuits, and the frequency of the alternating magnetic field is detected by measuring the alternating current voltage obtained from the respective intermediate terminals. A position sensor using a magnetoresistive element, characterized in that (d) the first magnetoresistive circuit and the second magnetoresistive circuit are electrostatically shielded from each other. A position sensor that uses the body. 2. The first magnetoresistive circuit and the second magnetoresistive circuit are formed on the same plate-shaped magnetic body, and the electrostatic shield is formed on the plate-shaped magnetic body in a region sandwiched between the two circuits. Claim 1 realized with a linear conductor formed on a magnetic material
A position sensor made using the magnetoresistive material described in 2. 3. The first magnetoresistive circuit and the second magnetoresistive circuit are formed on the same plate-shaped magnetic material, and the electrostatic shielding includes an insulating layer on the two magnetoresistive circuits. The two magnetoresistive circuits of the conductor layer and/or the plate-shaped magnetic body are formed in a position that is isolated from and faces the two magnetoresistive circuits through or through a space. A position sensor made using the magnetoresistive material according to claim 1, which is realized by having a conductive layer disposed on the non-conductive side surface. 4. The alternating magnetic flux moving in the specific direction is generated by a magnetic flux generating means disposed facing one surface of the two magnetoresistive circuits, and a magnetic flux generating means disposed facing the other surface of the two magnetoresistive circuits. A change in reluctance caused by the rotation of the cylindrical member that moves in the specific direction and has regularly formed gear-like unevenness. A position sensor made using the magnetic resistor described in item 3. 5. The alternating magnetic flux moving in the specific direction is generated by a magnetic flux generating means disposed facing one surface of the two magnetoresistive circuits, and a magnetic flux generating means disposed facing the other surface of the two magnetoresistive circuits. A change in reluctance caused by the movement of a rod-shaped member that moves in the specific direction and has regularly formed rack-like unevenness in the specific direction.
A position sensor made using the magnetoresistive body according to item 1, 2, or 3. 6. The alternating magnetic flux moving in the specific direction is generated by a magnetic flux generating means disposed facing one surface of the two magnetoresistive circuits and a magnetic flux generating means disposed facing the other surface of the two magnetoresistive circuits. A change in reluctance caused by the rotation of the cylindrical member that moves in the specific direction and has regularly formed slits, according to claim 1, 2, or 3. A position sensor made using the magnetoresistive material described above. 7. The alternating magnetic flux moving in the specific direction is generated by a magnetic flux generating means disposed facing one surface of the two magnetoresistive circuits and a magnetic flux generating means disposed facing the other surface of the two magnetoresistive circuits. and a change in reluctance caused by the movement of a rod-shaped member having regularly formed slits in the specific direction.
A position sensor made using the magnetic resistance body according to item 2 or 3.