JPH07104124B2 - Position detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a position of an object to be detected on the basis of the magnetic field strength from the magnet which is provided in the vicinity of the object to be detected having a magnet and which changes with the relative position change with the object to be detected. The present invention relates to a position detecting device for detecting.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
A magnetoelectric conversion element 5 whose electric characteristics change in accordance with the strength of a magnetic field in a predetermined direction is provided near the detected body 2 including the magnetoelectric conversion element 5, and the magnetoelectric conversion element 5 is connected to an electric circuit 7 and a display means 8. Accordingly, there is known a position detecting device 3 which converts the magnetic field intensity from the magnet 1 which changes with the relative position change with respect to the detected body 2 into a change in the potential difference or the current value and displays it on the display means 8.

[0003]

However, the electric characteristics of the magnetoelectric conversion element 5 in such a conventional position detecting device 3 change according to the strength of the magnetic field in a predetermined direction, and the magnetic characteristics of the magnetic field other than the predetermined direction are changed. Even if the strength changes, the electrical characteristics hardly change, so that the conventional position detecting device 3 has a problem in the accuracy and accuracy of the position detection of the detected object 2.

For example, when a magnetoresistive (MR) element whose resistance value changes depending on the strength of a magnetic field in the horizontal direction is used as the magnetoelectric conversion element 5, the reciprocating magnet 1 and the MR element are relatively moved. The relationship between the position and the strength of the horizontal magnetic field from the magnet 1 that effectively acts on the MR element is as shown in Fig. 7a), and the strength of the horizontal magnetic field is maximum at the point 0 where the magnet 1 is closest to the MR element. electrical characteristics of the MR element changes largely becomes a maximum also MR output voltage as shown in FIG. 7b)
Become. Then, as the magnet 1 moves away from the MR element,
The horizontal magnetic field from the magnet 1 to the MR element becomes weaker.
Along with that, the vertical magnetic field in the direction orthogonal to the magnetic field becomes stronger.
Therefore, the MR element receives a diagonal magnetic field from the magnet 1.
Then, the MR output voltage becomes smaller. And further
Then, when the magnet 1 reaches the position indicated by point X, the MR element receives
The horizontal magnetic field is minimized (that is, at point X
(Because it becomes a complete vertical magnetic field), the MR output voltage is also minimum.
It However, the relative distance between the magnet 1 and the MR element is much larger.
When it gets louder, the MR element will again move from the magnet 1 to the oblique magnetic field.
As a result, the MR element will be affected by its magnetic field.
The electrical characteristics are changed according to the horizontal component of the
The pressure is between the maximum and minimum values as shown by the dotted line in Figure 7b).
Will change.

That is, the magnet 1 and the MR element are closest to each other.
The maximum MR output voltage when the
Those that decrease as the relative distance to the child increases
, The magnet 1 goes beyond the X point and moves further away from the MR element
And a certain amount of horizontal magnetic field is applied to the MR element.
As a result, the electrical characteristics of the MR element change and the MR
The output voltage will increase again. That
Therefore, in the above-described conventional position detecting device 3, the target device including the magnet 1 is used.
The position of the detection object 2 cannot be detected accurately.
Will end up. Also, for example, based on the MR output voltage, the magnet 1
To determine the closest approach to the MR element,
MR output after the magnet 1 exceeds the X point above the judgment reference value
Must be set higher than the voltage, which results in M
The setting margin for the maximum value of the R output voltage becomes small.
And it will be erroneously detected due to the influence of noise and disturbance.
There was a risk that it would end up.

Therefore, the present invention was created for the purpose of accurately and reliably detecting the position of the object to be detected.

[0007]

According to such a constitution of the present invention, a magnetic field from the magnet which is arranged in the vicinity of the object to be detected and which is provided with the magnet and which changes with the relative position change with the object to be detected. A position detecting device for detecting the position of the object to be detected based on strength, the pair detecting device detects a position of the magnet when the magnet comes closest to the position .
In the direction of the straight line connecting the two magnetic poles of the magnet
A magnetoelectric conversion element that is arranged so as to receive a magnetic field in a horizontal direction and whose electrical characteristics change according to the magnetic field strength in that direction, and a surface of the magnetoelectric conversion element that faces the magnet.
And at least one of the opposite sides of the
A position detecting device, comprising: a magnetic thin film for magnetic induction, which is covered via an edge body .

[0008]

In the position detecting device of the present invention , the magnetoelectric conversion element is used.
The child faces the magnet when it is closest, and
At that time, make sure that the
It is arranged to receive a magnetic field in the direction. And porcelain
The electric conversion element has the magnetic field strength in that direction, that is, the magnet is the closest.
Electrical depending on the horizontal magnetic field strength received when attached
Change the characteristics. Also, in the magnetoelectric conversion element
The lesser of the opposite surface and the opposite surface
At least one is a magnetic thin film for magnetic induction through an insulator.
Is covered. In such a position detecting device of the present invention
At the same time, as the relative position of the magnet changes, the magnet
When it comes closest to the conversion element, the magnetoelectric conversion element
A magnetic field in the direction horizontal to the straight line connecting the poles (hereinafter, this direction
Direction magnetic field is also called a horizontal magnetic field),
The horizontal magnetic field is the magnetic thin film that is covered on the surface of the magnetoelectric conversion element.
Since it is parallel to the plane direction of the film, it is hardly affected by the magnetic thin film.
Without it, it extends to the magnetoelectric conversion element. Therefore, this
When, the magnetoelectric conversion element receives the magnetic field from the magnet,
Maximize its electrical properties.

From this state, the magnet and the magnetoelectric conversion element are
The relative position to the child changes in the direction of the straight line connecting the two magnetic poles of the magnet
Then, as the relative distance between the two increases,
When the horizontal magnetic field from the
The magnetic field in the direction orthogonal to the plain magnetic field (hereinafter, the magnetic field in this direction
(Also called vertical magnetic field) becomes stronger, so the magnetoelectric conversion element
For the surface facing the magnet and the surface opposite the surface
It receives a magnetic field in an oblique direction. Here, the present invention
In the position detection device, the magnet is moved diagonally from the magnetoelectric conversion element.
When a magnetic field is applied, it is the surface of the magnetoelectric conversion element.
The magnetic thin film covered with an insulator on the
It has been corrected so that the electrical characteristics of the electrical conversion element do not change.
It That is, the oblique magnetic flux (magnetic force) emitted from the magnet
(Line) tries to enter and exit perpendicularly to the magnetic thin film.
Therefore, the magnetic field from the magnet acts horizontally on the magnetoelectric conversion element.
Corrected in a direction almost orthogonal to the magnetic field,
It will be covered. Therefore, the electrical characteristics of the magnetoelectric conversion element
The amount of change is when the magnet and the magnetoelectric conversion element come closest to each other.
It becomes maximum and decreases rapidly when the relative distance between the two increases.
Will be less. Then, the phase of the magnet and the magnetoelectric conversion element
When the pair distance reaches a specified value, the magnetoelectric conversion element
When it comes close to the
Normal magnetic field is maximum while normal magnetic field is minimum (zero)
The electrical characteristics of the magnetoelectric conversion element hardly change
However, the relative distance between the magnet and the magnetoelectric conversion element becomes larger.
Then, the magnetoelectric conversion element again receives the oblique magnetic field from the magnet.
I will start to kick. However, in this case, the magnetoelectric conversion element
The received magnetic field in the diagonal direction is weak to some extent.
Therefore, the magnetic field is generated by the above-mentioned inductive action of the magnetic thin film.
As a result, it does not act on the magnetoelectric conversion element.

As described above, according to the position detecting device of the present invention,
For example, the relative position of the magnet and the magnetoelectric conversion element is
When changing in the direction of the line connecting the magnets, the magnet and magnetoelectric conversion element
As the relative distance from the child increases, the magnetoelectric conversion element
Make sure that the change in the electrical characteristics of the child is small.
You can The relative position of the magnet and the magnetoelectric conversion element
Is the one that is orthogonal to the direction of the straight line connecting both magnetic poles of the magnet
Direction from the magnet to the magnetoelectric conversion element
The magnetic field in the direction is simply weakened, and again,
As the relative distance between the stone and the magnetoelectric conversion element increases,
The amount of change in the electrical characteristics of the magnetoelectric conversion element becomes small. Obey
According to the position detecting device of the present invention,
, The relative distance between the magnet and the magnetoelectric conversion element is
However, the amount of change in the electrical characteristics of the magnetoelectric conversion element
To prevent inconveniences such as becoming large
Based on changes in the electrical characteristics of the magnetoelectric conversion element.
Therefore, the position of the detected object can be detected accurately and reliably.
become able to. In addition, the electrical characteristics of the magnetoelectric conversion element
Based on the amount of change, the magnet and the magnetoelectric conversion element should be closest to each other.
When determining, the judgment reference value is the electrical characteristics.
The maximum value of the change amount of (the magnet and the magnetoelectric conversion element
Can be set smaller than the value when
Therefore, the influence of noise and disturbance can be suppressed, and
You will be able to make decisions. Furthermore, the electric power of the magnetoelectric conversion element
The amount of change in the air characteristics is the relative distance between the magnet and the magnetoelectric conversion element.
Becomes larger, it will decrease sharply.
More accurately to detect that the
Can be issued.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the one example described in detail below, within a range not departing from the gist of the present invention,
It includes all examples that can occur to those skilled in the art.

As shown in FIG. 1, a piston position detecting device 10 which is an embodiment of the present invention is attached to the outer wall of a cylinder 90 made of a non-magnetic material, and the inside of the cylinder 90 is shown in FIG.
Is for detecting the position of the piston 92 based on the strength of the magnetic field from the permanent magnet 1 embedded in the piston 92 that slides in the left-right direction . The permanent magnet 1 is
It is formed in a cylindrical shape along the peripheral surface of the stone 92.
In Fig. 1, the left and right sides are the north pole and the south pole, respectively (Fig. 7).
reference).

In the piston position detecting device 10, each element constituting the detection circuit 62 is arranged on the surface of the printed board 60, and the magnetoresistive (MR) element chip 20 is attached to the back surface of the printed board 60. A lead wire 70 for supplying power to the detection circuit 62 is also connected to the back surface of the printed circuit board 60. And the cylinder 90
A shield cover 80 made of a steel plate is provided to cover the printed circuit board 60, the detection circuit 62, the MR element chip 20 and the like except for the mounting surface side thereof. A base 82 made of synthetic rubber is attached to the periphery of the opening of the shield cover 80, and the position detection device 10 is attached to the cylinder 90 by fixing the base 82 to the outer wall of the cylinder 90.

The MR element chip 20 has a magnetic resistance (M) made of permalloy on the surface, as schematically shown in FIGS.
R) Pattern forming portion 25 of the glass substrate 22 (see FIG. 4) on which the element pattern 24 and the solder pad portion 26 are formed
After covering the surface of the substrate with the insulator 34 of SiO ₂ , the insulator 3
4, a cobalt-based amorphous magnetic thin film 30 having a thickness of 10 μm and a magnetic thin film 32 having a thickness of 5 μm are laminated on the front surface of the substrate 4 and the back surface of the substrate 22, respectively.
It is formed by stacking an insulator 36 of SiO ₂ on the above. Note that only the nickel plating 27 is applied to the upper surface of the solder pad portion 26.

As shown in FIG. 5, the MR element chip 20 is manufactured through a cleaning process (I) to a dicing process (X). First, in the cleaning step (I), the glass substrate 22
The surface of the substrate is cleaned by washing a in a cleaning layer with a neutral detergent, and preparation is made so that vapor deposition in the next step can be performed well. In the vapor deposition process (II), the ICB is attached to one side surface of the substrate 22a.
The permalloy 40 is vapor-deposited by the vapor deposition device. Further, in the resist process (III), a spinner was used to permloy 4
Photoresist 41 is applied to the outer surface of 0 and prebaked.

After the pre-baking, in the exposure step (IV), the working surface having a plurality of pattern shapes as shown in FIG. After the irradiation, in the developing step (V), the developing solution is stored in a developing tank for development, and a plurality of MRs are formed by the photoresist 41 applied to the vapor deposition film on the substrate 22a.
Shape the element pattern. Further, after this is post-baked, in the etching step (VI), the permalloy 40 not covered with the photoresist 41 is corroded in the etching tank to form the MR element pattern 24 and the solder pad portion 26 by the permalloy 40.

In the stripping step (VII), the remaining photoresist 41 is stripped. Then, in the magnetic film forming step (VIII), MR
A mask exposing the pattern forming portion 25 on which the element pattern 24 is formed is covered, an insulator 34 is laminated on the pattern forming portion 25, and nickel plating 27 is applied on the solder pad portion 26. Further, a magnetic thin film 32 is vapor-deposited on the insulator 34, and the magnetic thin film 30 is entirely formed on the opposite side surface of the substrate 22a.
Vapor deposition.

Then, the heat treatment process (IX) in a vacuum high temperature furnace
Then, in the dicing process (X), each MR element chip 20 is formed by cutting each pattern of about 4 mm square. The heat treatment step (IX) is not an essential step and may be omitted.

Next, the detection circuit 62 provided on the printed circuit board 60 will be described with reference to FIG. Detection circuit 62
Is a resistor R1 that divides the power supply voltage to set a reference voltage,
R2, an MR element chip 20 provided in parallel with those resistors, and a comparator 72 and a comparator 72 for comparing the magnitude of a set reference voltage and an MR output voltage that changes based on a change in the resistance value of the MR element chip 20. It is composed of a pnp-type transistor 74 which is connected to an output section and is turned on and off based on the output, and a display lamp 68 which is turned on when the transistor 74 is turned on, and receives electric power from a power source 78 via a lead wire 70. There is.

The relative positional relationship between the permanent magnet 1 interlocked with the piston 92 in the cylinder 90 and the MR element chip 20 provided in the position detection device 10 and the operating principle of the detection circuit 62 are shown in FIGS. This will be described in detail with reference to FIG.

As shown in FIG. 7a, when the permanent magnet 1 moves on the line P, the state of the magnetic flux reaching the MR element chip 20 at the point 0 is as follows. This is the same as the state of the magnetic flux when the MR element chip 20 moves on the line Q including the.

As shown in FIGS. 7a) to 7c), when the permanent magnet 1 is closest to the MR element chip 20, the horizontal component of the magnetic flux density reaching the MR element chip 20 is the maximum, so that M
The R output voltage also becomes maximum. At that time, since the MR output voltage exceeds the reference voltage set by the resistors R1 and R2, the out output voltage of the comparator 72 becomes Low, the transistor 74 is turned on, and the display lamp 68 is turned on.

When the permanent magnet 1 moves away from the MR element chip 20 and the horizontal magnetic flux density reaching the MR element chip 20 decreases, the MR output voltage also decreases and falls below the reference voltage. Then, the out output voltage of the comparator 72 also becomes Hi, the transistor 74 is turned off, and the display lamp 68 is also extinguished.

By the way, as can be understood from the state of the magnetic flux indicated by the dotted line in FIG. 7a), the magnetic flux density is the MR element chip 20.
Since there is only a vertical component when is at point X, the MR output voltage takes a minimum value (see FIG. 7b). Permanent magnet 1 is MR
The horizontal magnetic flux density component, which is maximum when the element is closest to the element chip 20, decreases as it approaches the point X, and becomes zero at the point X. However, when the permanent magnet 1 further moves away from the MR element chip 20 beyond the point X, a horizontal magnetic flux density component of a certain magnitude is generated again.

Therefore, in the conventional example having no magnetic thin film, as shown by the dotted line in FIG. 7b), although the MR output voltage once becomes the minimum at the X point, it exceeds the X point and the permanent magnet 1 However, when the distance from the MR element chip 20 is further increased, the MR output voltage also increases again corresponding to the regenerated horizontal magnetic flux density component.

However, according to this embodiment, the magnetic thin films 30 and 32 having high magnetic permeability are arranged above and below the MR element pattern 24 of the magnetoresistive body to induce the magnetic field, and the permanent magnet 1 is crossed beyond the X point. Even if it is moved away from the MR element chip 20, most of the magnetic flux density component in the horizontal direction is the MR element pattern 2.
4 and thus, as indicated by the solid line in FIG. 7b), the MR output voltage also becomes minimum at the point X and then remains at its minimum value.

FIG. 8 shows experimental data (corresponding to the principle diagram of FIG. 7b) in the case of actually performing an experiment using the position detecting device. Experimental data obtained by a conventional position detecting device that does not use the magnetic thin films 30 and 32 shows that the piston is displaced from the position of the maximum MR output voltage where the permanent magnet is closest to the MR element, as shown by the dotted line in FIG. Along with this, the MR output voltage decreases, and becomes the minimum once at the point X, but the MR output voltage increases again and becomes a curve having three peaks. Therefore,
For example, only at the position where the permanent magnet is closest to the MR element,
In order to make the MR output voltage exceed the reference voltage, it is necessary to set the reference voltage to a high value of about 80 mv.
The difference between the reference voltage and the maximum MR output voltage (about 90 mv) was small, and there was concern about the detection accuracy of the piston position. Specifically, for example, there is a possibility that the piston position may be erroneously detected due to noise or disturbance of only 10 mv. On the other hand, according to the present embodiment whose experimental data is shown by the solid line in FIG. 8, when the permanent magnet 94 comes closest to the MR element chip 20, the MR output voltage maximum value (about 87 mv) is taken and the maximum value is obtained. A beautiful mountain-shaped curve with only the tip as the peak. Therefore, in this embodiment, the reference voltage can be set low (for example, 50 mv or less), and the position of the piston 92 can be reliably detected.

Further, as shown by the dotted line in FIG. 8, in the conventional example, there is a width in the piston position where the MR output voltage is maximum (that is, the apex of the graph curve is unclear). On the other hand, according to the present embodiment, as shown by the solid line in FIG. 8, in the vicinity of the maximum MR output voltage, there is a large change in the graph, and it is possible to specify the piston position that exhibits the maximum MR output voltage. (Compared to the conventional example, the apex of the graph curve is sharper in the embodiment). Therefore, according to this embodiment,
The MR output voltage is maximized only when the permanent magnet 1 comes closest to the MR element chip 20, and the piston 9
The detection accuracy of the position 2 can be improved.

In order to support the effect produced by this embodiment, the magnetic flux density from the permanent magnet 101 interlocking with the piston 192, as shown in FIG.
Five-point detection unit 200 corresponding to the position of the element pattern 24
A finite element analysis model to detect and analyze with is designed. Based on this model, the position at which the head of the piston 192 and the reference position head 190 of the cylinder contact each other is set to zero displacement, and analysis is performed at displacement positions of 5, 9, 10 and 20 mm associated with the movement of the piston 192. The analysis results are shown in FIGS. 10 to 14, respectively. In each figure, (A), (B), and (C) are respectively
Corresponding to the present embodiment, two amorphous magnetic thin films 13
0 and 132 are used, a single amorphous magnetic thin film 130 is used, and a case corresponding to a conventional example in which the amorphous magnetic thin film is not used are shown. In each of these drawings, a schematic diagram showing the displacement of the piston 192 is shown. At the same time, the state of the magnetic flux in the vicinity of the detection unit 200 and the magnetic flux vector in the detection unit 200 are each enlarged and shown.

At the position of zero displacement, as shown in FIG. 10, there are a case where the detection unit 200 is provided between the two amorphous magnetic thin films 130 and 132 (A) and a case where the amorphous magnetic thin film is not used (C). Then, the appearance of magnetic flux is almost unchanged. This is because the magnetic saturation occurs in the two magnetic thin films 130 and 132. On the other hand, when the amorphous magnetic thin film 130 is provided only between the permanent magnet 101 and the detection unit 200 (B), the thin film 130 induces a magnetic field even when the displacement is zero.

At each of the displacements of 5, 9, 10 and 20 mm, as shown in FIGS. 11 to 14, the amorphous magnetic thin films 130 and 132 were used as compared with the case where the amorphous magnetic thin film was not used (C). In both the case (A) and the case where a single amorphous magnetic thin film 130 is used (B), the magnetic field is induced by the amorphous magnetic thin film 130 or 132, and the magnetic flux from the magnetic thin film 130 to the detection unit 200 causes the thin film 130 surface. Corrected vertically to
There is. That is, as the piston 192 moves, the permanent magnet
An oblique magnetic flux goes from 101 to the detection unit 200.
However, the magnetic flux falls on the magnetic thin films 130 and 132.
Since it tries to enter directly and exit vertically,
Will have a vertical magnetic flux. And then
In this case, the magnetic thin film 130 is more than the magnetic thin film 130 (B),
In the case of 132 sheets (A), the magnetic flux is more strongly induced in the direction perpendicular to the surface of the thin film 130.

Further, regarding the vector locus of the magnetic flux density in the detection unit 200 due to the displacement in the above analysis, the case of two amorphous magnetic thin films 130 and 132 (A) is shown in FIG.
FIG. 5 shows the case where the magnetic thin film is not used (B) in FIG. 15 and 16, with the position of the detection unit 200 as the origin, the piston 192 (and the permanent magnet 10).
The vector component of the magnetic flux density parallel to the displacement direction of 1) is taken on the Y axis, and the vector component orthogonal to it is taken on the X axis.

Also in FIGS. 15 and 16, the influence of the amorphous magnetic thin films 130 and 132 inducing a magnetic field is shown. That is, the two magnetic thin films 130,
In the case shown in FIG. 15 in which 132 is placed on both sides of the detection unit 200, the horizontal component of the magnetic flux density decreases as the displacement increases from the displacement zero point of the maximum magnetic flux density in the horizontal direction. Once it reaches zero, the horizontal component of the magnetic flux density continues to take a value of approximately zero, even if the displacement increases from that point. On the other hand, in the case shown in FIG. 16 in which the magnetic thin film is not used, even if the horizontal component of the magnetic flux density once becomes zero, when the displacement further increases, it is in the opposite direction from that until then, but the magnitude is constant. The horizontal component of is detected.

As described above in detail, in this embodiment, the amorphous magnetic thin film 30 formed on the back surface of the substrate 22 and the amorphous magnetic thin film formed on the surface of the insulator 34 laminated on the MR element pattern 24 are used. the thin film 32, Hisashi
Magnetism in a diagonal direction from the permanent magnet 1 to the MR element pattern 24 surface
The field is modified in a substantially vertical direction. Therefore, the piston 92
Is beyond the X point in FIG.
20) Water from the permanent magnet 1 when moving away from
Diagonal magnetic fields containing flat components are corrected almost vertically.
And the MR element pattern 24 is reached.
As a result, the MR element pattern 24 responds to the displacement of the piston 92.
It will receive a horizontal magnetic field of the same strength. Therefore, FIG.
As shown in FIG.
The R output voltage is maximum only when the piston 92 comes closest to the MR element pattern 24, and exhibits a good mountain-shaped characteristic with the maximum value as the apex. Therefore, based on the excellent MR output voltage characteristic, the accuracy of detecting the position of the piston 92 can be enhanced, and the position of the piston 92 can be reliably detected by setting the reference voltage to a low value.

In addition, it was difficult to form the entire device with a constant thinness (1 μm to 30 μm) suitable for magnetic induction with high accuracy (there will be a change in characteristics even if it is formed to an appropriate thinness). Magnetic thin films 30, 3 compared to
2 can be accurately formed to a certain thinness by controlling the characteristics by a thin film forming technique such as an ion plating beam method, vacuum vapor deposition, or sputtering, and can accurately induce a magnetic field. Therefore, according to this embodiment using such magnetic thin films 30 and 32, it is possible to properly control the MR output voltage and accurately detect the position of the moving body.

Further, as described above, according to this embodiment, which can obtain a better MR output voltage characteristic than the conventional example, there is a tolerance in setting the reference voltage, so that the detection circuit 6
2 can flexibly respond to temperature changes and external disturbances, and MR
It has become possible to make the element chip 20 a general-purpose one. That is, the MR element chip 20 having a good MR output voltage characteristic can be effectively used for another position detecting device having a variation in the reference value due to the difference in the magnetic force of the permanent magnet or the electric circuit.

In addition, in this embodiment, two magnetic thin films 3 are used.
Since the magnetic field from the permanent magnet 1 is induced by 0 and 32, the magnetic field can be induced more accurately as compared with the case where only the magnetic thin film 30 is induced ((A) and ((A) in FIGS. 10 to 14). (See B)), the MR output voltage can be controlled more appropriately to improve the accuracy and accuracy of detecting the position of the piston 92.

Further, the amorphous magnetic thin films 30 and 32 used in the present embodiment can be mass-produced at low cost because the film forming conditions are looser and the manufacturing is easier than that of a general crystal film.

In addition, the MR used in this embodiment
The element chip 20 undergoes a manufacturing process as shown in FIG.
That is, since the film formation for the plurality of MR element chips 20 is performed on the glass substrate 22a at one time by vapor deposition, the individual element chips 20 are cut into pieces, so that the MR element chips 20 having uniform characteristics can be easily formed. Mass production is possible.

Although two magnetic thin films were used in this embodiment, it is clear from comparing FIGS. 10 to 14 (B) and (C) that only one of the two magnetic thin films is used. However, by guiding the magnetic field from the permanent magnet 1 to the MR element pattern 24, a better MR output voltage characteristic can be obtained as compared with the case where no magnetic thin film is used, and the position of the piston 92 can be detected more accurately and reliably. I can.

If a material having a magnetic anisotropy that the magnetic permeability in the vertical direction is small and the magnetic permeability in the horizontal direction is large is used for the amorphous magnetic thin films 30 and 32 in the above-described embodiment, the magnetic anisotropy is reduced. By controlling not only the direction of the magnetic flux density but also the size of the magnetic flux density by utilizing it, M can be obtained only when the permanent magnet 1 comes closest to the MR element chip 20.
It is also possible that the R element pattern 24 is covered by the magnetic flux density component in the horizontal direction.
The accuracy of 0 can be further improved.

Further, as a material for the magnetic thin films 30 and 32,
In addition to the ferromagnetic material such as the amorphous material used in this embodiment , any magnetic material such as a diamagnetic material or a weak magnetic material capable of forming a thin film by vapor deposition can be used. If the change in the electrical characteristics of the magnetoelectric conversion element corresponding to the change in the relative position between the magnet and the magnetoelectric conversion element can be realized by magnetic induction, it has a magnetic permeability different from that of air and a small coercive force . This is because various substances can be used as the material of the magnetic thin film .

The position detecting apparatus according to the present invention is not limited to the case of detecting the position of a reciprocating moving body such as a piston as in the present embodiment, but it is not limited to a rotating body such as a motor or a motion other than reciprocating motion. It can also be used to detect the position of a moving body that moves. Contrary to the case where the magnet side moves and the position detecting device is fixed as in this embodiment, the magnet is fixed to the cylinder and the position detecting device is attached to the piston.
It may be a case where the magnet side is fixed and the position detecting device moves. Further, although the permanent magnet 1 is used as the magnet in the present embodiment, instead of this, an electromagnet, a conductor through which an electric current flows, or the like.
It is also possible to use various things which generate a magnetic field.

In this embodiment, the substrate 2 on which the magnetic thin film is formed
Although glass is used as the material 2, silicon, ceramics, or the like may be used. Further, in this embodiment, an organic insulating material such as polyimide may be used as the insulators 34 and 36 using SiO ₂ .

Instead of the ferromagnetic metal resistance element (MR element) used in this embodiment, a Hall element, a semiconductor magnetoresistance element or the like can be used as a magnetoelectric conversion element .

[0046]

As described above in detail, the present invention
In the position detector, it faces the magnet of the magnetoelectric conversion element.
Side surface and at least one of the opposite surfaces.
The magnetic thin film for magnetic induction through the insulator.
Since it is done so, the direction from the magnet to the magnetoelectric conversion element
Is applied to the magnetic thin film,
Direction in which the electrical characteristics of the magnetoelectric conversion element do not change due to conduction
Will be corrected to.

Therefore, the electrical characteristics of the magnetoelectric conversion element are
Distance from the magnet that changes as the relative position to the detection object changes
Faithfully changes, and as a result, the position of the object to be detected can be detected accurately and reliably.

In particular, since the magnetic thin film for magnetic induction used in the position detecting device according to the present invention can be easily formed with a high thickness accuracy by a thin film forming technique such as vapor deposition, the desired induction against the magnetic field is obtained. Can be done accurately.

Therefore, in the position detecting device according to the present invention using such a magnetic thin film , it is possible to accurately and surely detect the position of the object to be detected by appropriately guiding the magnetic field.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a piston position detection device 10 according to an embodiment of the present invention mounted on a cylinder 90.

2 is an enlarged side view of the MR element chip 20. FIG.

FIG. 3 is an exploded view of the MR element chip 20.

FIG. 4 is a pattern diagram on the surface of a substrate 22.

FIG. 5 is a manufacturing process diagram of the MR element chip 20.

FIG. 6 is an electric circuit diagram of the position detection device 10 according to the present embodiment.

FIG. 7 is an explanatory diagram of changes accompanying displacement of a piston.

FIG. 8 is an MR output voltage characteristic diagram based on an experiment.

FIG. 9 is an explanatory diagram of a finite element analysis model assuming the present embodiment.

10 is an explanatory diagram showing a case of zero displacement of a finite element analysis result using the model shown in FIG. 9. FIG.

11 is an explanatory diagram showing a case of a displacement of 5 mm as a finite element analysis result using the model shown in FIG.

12 is an explanatory diagram showing a case of a displacement of 9 mm as a finite element analysis result using the model shown in FIG.

13 is an explanatory diagram showing a case of a displacement of 10 mm as a finite element analysis result using the model shown in FIG.

14 is an explanatory diagram showing a case of a displacement of 20 mm as a finite element analysis result using the model shown in FIG.

FIG. 15 shows two amorphous magnetic thin films 130 and 132.
It is explanatory drawing which showed the finite element analysis result at the time of using as a vector locus.

FIG. 16 is an explanatory diagram showing, as a vector locus, a finite element analysis result in the case of supporting a conventional technique that does not use an amorphous magnetic thin film.

FIG. 17 is a block diagram illustrating a conventional example.

[Explanation of symbols]

1 ... Magnet, 10 ... Piston position detecting device, 20 ... MR element chip, 22 ... Substrate,
24 ... MR element pattern, 26 ... Solder pad portion, 3
0, 32 ... Magnetic thin film, 34, 36 ... Insulator, 60 ... Printed circuit board, 62 ... Detection circuit, 68 ... Indicator lamp, 70 ... Lead wire, 72 ... Comparator,
80 ... shield cover, 92 ... piston,

Claims (1)

[Claims] 1. A position of the object to be detected is detected based on a magnetic field strength from the magnet, which is arranged in the vicinity of the object to be detected having a magnet and changes with a relative position change with the object to be detected. A position detecting device that faces the magnet when the magnet comes closest and
Sometimes the horizontal direction of the straight line connecting both poles of the magnet
A magnetoelectric conversion element that is arranged so as to receive a magnetic field and whose electrical characteristics change according to the magnetic field strength in the direction, and a surface of the magnetoelectric conversion element that faces the magnet,
On at least one of the opposite sides of that side, insulator
And a magnetic thin film for magnetic induction which is covered with the position detecting device.