JPH08201108A - Position detection device and magnetoresistive effect element - Google Patents

Abstract

(57) [Summary] [Object] To provide a position detection device and a magnetoresistive effect element capable of obtaining highly accurate position information. According to the magnetoresistive effect element of the present invention, at least one magnetic detector whose resistance value changes in response to a magnetic field in a scale portion having magnetic poles alternately magnetized at a predetermined interval is substantially a magnetic pole. Forming a magnetic detection group that is arranged at the same distance as the formation width of the magnetic poles, and the magnetic detection groups are arranged in pairs that are separated by a distance that is substantially half the magnetic pole formation width. A voltage is applied to both ends of the series connection of the detection group, and the output is obtained from the middle point.Furthermore, among the wiring parts necessary for voltage application and signal output, the magnetic field in the scale part and The wiring part in the orthogonal direction is composed of a wiring group composed of a plurality of wiring parts,
For each of the magnetic detection groups, a pair of wiring groups formed with a distance substantially the same as the width of the magnetic poles formed are arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device for detecting the position of an object, and particularly to a position for detecting the position of an object with high accuracy and high resolution by using a magnetoresistive effect element (MR element). The present invention relates to a detection device.

[0002]

2. Description of the Related Art For example, a lens system having a zoom mechanism and a focus mechanism in a video camera is one of those requiring high-resolution position detection. In such a lens system, the subject distance at the focal point, the zoom lens position, and the focus lens position must have a predetermined positional relationship determined by the lens design. In order to satisfy this positional relationship, conventionally, a method of using a mechanical cam or a method of detecting the zoom lens position and the focus lens position and forming an electronic cam by calculation is used.

The method using a mechanical cam has problems such as a large device structure and a decrease in accuracy due to mechanical abrasion.

As a method using an electronic cam, there are a method using a potentiometer as a position detector, a method using a stepping motor as a lens driving motor, and a method for counting control signals of the stepping motor. However, the method using the potentiometer has problems that the load applied to the motor is increased because of the contact type, the linearity is deteriorated due to the dispersion of the resistance film, the reliability is low, and the like.
On the other hand, the method of counting the control signals of the stepping motor can be applied only to the lens system using the stepping motor as the motor. Further, if there is an object, such as a gear, interposed between the motor and the lens, an error occurs due to the play (play).

As a method for solving the above problems, it is possible to use an MR element. That is, the characteristic that the resistance value of the MR element changes according to the change of the magnetic field is used. For example, there is a method in which a magnet is mounted on the lens side, an MR element is arranged on the fixed side, the magnet is moved with respect to the MR element by moving the lens, and the resistance change is extracted as a position change.

FIG. 5 shows a pattern for forming a conventional MR element. The MR element has four magnetic detectors M1, M2, M
3 and M4. These magnetic detectors M1, M2, M
3, M4 is a ferromagnetic thin film, for example, a thin nickel-iron alloy film is formed on a glass substrate by vacuum deposition or sputtering in a magnetic field, and two thin lines are formed by etching or the like. . The folded portion 1 has a large line width in order to reduce the resistance value. The magnetic detectors M1, M2, M3, M4 are formed long in a direction orthogonal to the direction of the magnetic field of the magnet 7 so that the resistance value is changed by the magnetic field of the magnet (scale part) 7. The connection lines 2 connecting the magnetic detectors M1 and M2, M2 and M3, and M3 and M4, respectively, are formed of the same ferromagnetic thin film as that of the magnetic detectors, so that the magnetic field of the magnets 7 does not cause resistance change. 7 is formed in a direction parallel to the direction of the magnetic field. In order to reduce the resistance value, the line width of the connection line 2 is formed thick. Reference numerals 4 and 6 are external connection terminals for applying power to the MR element, and reference numeral 5 is an external connection terminal for extracting an output signal of the MR element. The external connection terminals 4, 5, 6 are formed of the same ferromagnetic thin film as the magnetic detector. The magnetic detector M1 and the external connection terminal 4, the magnetic detector M4 and the external connection terminal 6, and the connection line 2 between the magnetic detectors M2 and M3 and the external connection terminal 5 are connected by a wiring portion 3. The wiring portion 3 is formed to have a thick line width in order to reduce the resistance value. The magnet 7 has N magnetic poles and S magnetic poles alternately formed at a certain predetermined interval P.

FIG. 6 shows an equivalent circuit diagram of the MR element. Further, FIG. 7 shows the relationship between each magnetic detector of the MR element and the magnetic pole in the magnet and the output signal waveform of the MR element. The magnetic detectors M1, M2, M3 and M4 cancel the error in the vicinity of the boundary between the adjacent N and S magnetic poles.
2, M3 and M4 are formed apart from each other by the magnetic pole forming width P of the magnet 7, and in order to make the output signal sinusoidal, a magnetic detection group 8 composed of magnetic detection elements M1 and M2 and a magnetic detection element The magnetic detection group 9 composed of M3 and M4 is formed with a phase shift of substantially P / 2.

Position information can be obtained by waveform-shaping the output signal of the MR element thus constructed into a pulse signal and measuring the edge thereof, and further, interpolating the output signal in an analog manner. Thus, position information with higher resolution can be obtained.

[0009]

However, in the above-mentioned conventional example, the wiring portion 3 is formed in a direction orthogonal to the magnetic field of the magnet 7, and the resistance value change due to the magnetic field also occurs in this portion. Original position information cannot be obtained.

Further, in the MR element, in general, the MR
There is a characteristic that the hysteresis of the resistance value change is different when the magnetic field applied to the element is increased and when it is decreased. FIG.
An example of a change in resistance value of the MR element when a magnetic field is applied in a direction orthogonal to the MR element is shown in FIG. In FIG. 8, the solid line is a curve showing the resistance value change when the magnetic field is decreased, and the broken line is the curve showing the resistance value change when the magnetic field is increased. The wiring portion 3 is formed without considering such characteristics. Therefore, in the conventional MR element, an error occurs when the position is measured with higher accuracy.

In order to solve the above problems, it is an object of the present invention to provide a position detecting device and a magnetoresistive effect element which can obtain highly accurate position information.

[0012]

In order to solve the above-mentioned conventional problems and to achieve the above-mentioned objects, a magnetoresistive effect element according to the present invention has a magnetic field in a scale portion having magnetic poles alternately magnetized at predetermined intervals. A magnetic detection group in which at least one magnetic detector whose resistance value changes in response to is disposed at a distance substantially the same as the magnetic pole formation width,
The magnetic detection groups are arranged in pairs at a distance of substantially half of the magnetic pole formation width, a voltage is applied across the series connection of the pair of magnetic detection groups, and an output is obtained from the midpoint. Further, among the wiring portions required for voltage application and signal output, the wiring portion in the direction orthogonal to the magnetic field in the scale portion is constituted by a wiring group consisting of a plurality of wiring portions, For each of the magnetic detection groups, a pair of wiring groups formed with a distance substantially the same as the width of the magnetic poles formed are arranged.

The magnetic detector and the wiring portion are preferably formed of a ferromagnetic thin film, and the magnetic detector belonging to the magnetic detection group and the wiring portion in a direction orthogonal to the magnetic field in the scale portion. Is n times the magnetic pole formation width P of the scale portion (n = 0, 1, 2, ...
It is better to form them with the distance of ().

Further, a highly accurate position detecting device can be provided by having the scale section described above and the sensor section composed of the magnetoresistive effect element described above.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. It should be noted that components having the same configurations or functions as those of the conventional technique are designated by the same reference numerals and described.

[First Embodiment] FIG. 1 shows a pattern diagram of forming an MR element as a sensor portion according to a first embodiment of the present invention. The MR element has four magnetic detectors M1, M2
It is configured to include M3 and M4. Magnetic detectors M1 to M4
Is a ferromagnetic thin film having a thickness of about 500 to 1000 angstrom, for example, a nickel-iron alloy film, formed on a glass substrate (not shown) by vacuum vapor deposition or sputtering in a magnetic field, and having a line width of about 10 μm by etching or the like. The thin line is folded back to form two lines. The folded portion 1 is formed to have a wide line width of about 100 μm in order to reduce the resistance value. The magnetic detectors M1 to M4 are formed long in a direction orthogonal to the direction of the magnetic field of the scale part 7 so that the resistance value is changed by the magnetic field of the scale part (magnet) 7.

On the other hand, the connecting wire 2 for connecting the magnetic detectors and the like is formed of the same ferromagnetic thin film as the magnetic detectors M1 to M4, so that the magnetic field of the scale portion 7 does not cause resistance change. 7 is formed in a direction parallel to the direction of the magnetic field. Further, in order to reduce the resistance value, the line width of the connection line 2 is set to about 100 μm. Reference numerals 4 and 6 are external connection terminals for applying power to the MR element, and reference numeral 5 is an external connection terminal for extracting an output signal of the MR element. The external connection terminals 4, 5, 6 are formed of the same ferromagnetic thin film as the magnetic detectors M1 to M4. The magnetic detector M1 and the external connection terminal 4 are the wiring portion 301, the magnetic detector M2 and the external connection terminal 5 are the wiring portion 302, the magnetic detector M3 and the external connection terminal 5 are the wiring portion 303, and the magnetic detector The wiring section 304 connects the M4 and the external connection terminal 6 to each other. Wiring part 30
1, 302, 303, 304 are also formed of the same ferromagnetic thin film as the magnetic detectors M1 to M4 and have a line width of about 10 μm.

Since the magnetic detectors M1, M2, M3 and M4 cancel the error near the boundary between the adjacent N and S magnetic poles, the magnetic detectors M1 and M2 and the magnetic detectors M3 and M4 are
They are formed so as to be separated from each other by the magnetic pole formation width P of the scale portion 7. Further, in order to make the output signal sinusoidal, a first magnetic detection group including magnetic detectors M1 and M2 and a second magnetic detector including magnetic detectors M3 and M4 are provided. It is formed to be substantially out of phase with the magnetic detection group by P / 2.

In the above-described first magnetic detection group, the wiring portion 301 and the wiring portion 302 are substantially out of phase with each other by the magnetic pole formation width P, that is, separated by an interval of m times the magnetic pole formation width P. State (however, m = 1, 3, 5, ...
・) Is formed. In the present embodiment, the magnetic pole formation width P
Are formed apart from each other by three times. With this structure, when a magnetic field in the increasing direction is applied to the wiring portion 301, a magnetic field in the decreasing direction is applied to the wiring portion 302. Therefore, when the applied magnetic field increases and decreases. The hysteresis characteristics with different resistance change histories are canceled by and. Similarly, also in the second magnetic detection group, the wiring portion 303 and the wiring portion 304 are substantially out of phase with each other by the magnetic pole forming width P (in the present embodiment, the magnetic pole forming width P).
(A state of being separated by a distance of 3 times). Therefore, when an increasing magnetic field is applied to the wiring part 303,
Since the magnetic field in the decreasing direction is applied to the wiring portion 304, the hysteresis characteristic in which the history of the resistance value change differs when the applied magnetic field increases and when the applied magnetic field decreases is canceled.

As described above, according to this embodiment,
Wiring portions 301 and 3 in a direction orthogonal to the magnetic field of the scale portion 7
It is possible to eliminate the error caused by the hysteresis property of the magnetic resistance change generated in 02, 303, 304, and it is possible to detect the position with high accuracy.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 shows the M of the second embodiment.
The formation pattern figure of R element is shown.

In FIG. 2, 305, 306, 307,
Reference numeral 308 is a wiring portion in a direction orthogonal to the magnetic field of the scale portion 7. The wiring portions 305, 306, 307, 308 are formed of the same ferromagnetic thin film as the magnetic detectors M1 to M4,
In order to reduce the resistance value, the line width is formed as wide as about 100 μm.

In the first magnetic detection group composed of the magnetic detectors M1 and M2, the wiring portion 305 and the wiring portion 306 are
Similar to the first embodiment, the phases are substantially shifted by the magnetic pole formation width P (in the present embodiment, the magnetic pole formation width P is separated by three times the interval). Therefore,
In the first magnetic detection group, the hysteresis property generated in the wiring portions 305 and 306 is canceled.

The magnetic detector M1 and the wiring portion 305 are
They are formed in substantially the same phase or in a state in which the phase is shifted by the magnetic pole formation width P, that is, a state separated by an interval n times the magnetic pole formation width P (where n = 0, 1, 2, 3, ...). ing. In this embodiment, the magnetic pole formation widths P are formed apart from each other. Magnetic detector M2 and wiring unit 306
Are also formed with a gap of the magnetic pole formation width P. This state is also a state in which the phase is shifted substantially by the same phase or the magnetic pole formation width P. Therefore, the wiring parts 305, 3
The magnetoresistive change generated at 06 is caused by the magnetic detectors M1 and M2.
The magnetic resistance changes in the same phase as the magnetic resistance change that occurs in the first magnetic detection group.

On the other hand, the wiring portion 307 and the wiring portion 308 are also the first
Of the magnetic detection group side of the wiring unit 307
And the hysteresis generated in the wiring portion 308 is canceled. Further, the magnetic resistance change generated in the wiring portions 307 and 308 is also in phase with the magnetic resistance change generated in the second magnetic detection group including the magnetic detectors M3 and M4.

In the second embodiment of the present invention, since the magnetoresistive change signal generated in the magnetic detection group and the magnetoresistive change signal generated in the wiring part are in phase, a plurality of sinusoids having different phases are used. An output waveform without waveform distortion can be obtained without waves being superimposed.

[Third Embodiment] Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 3 shows a pattern diagram of forming the MR element of the third embodiment, and FIG.
Shows its equivalent circuit diagram.

In this embodiment, M as a sensor unit
The R element is composed of eight magnetic detectors M5, M6, M7, M8,
It is configured to include M9, M10, M11, and M12. The magnetic detectors M5 to M12 are formed similarly to the magnetic detectors M1 to M4 in the first embodiment. However, this embodiment is different in that the magnetic detector is formed in one linear shape.

The connection line 2 connecting the magnetic detectors and the like and the external connection terminals 4, 5, 6 are also formed in the same manner as in the first embodiment. In this embodiment, the magnetic detector M5 and the external connection terminal 4 are the wiring portion 309, the magnetic detector M8 and the external connection terminal 5 are the wiring portions 310, and the magnetic detector M9 and the external connection terminal 5 are the wiring portions. At 311, the magnetic detector M12 and the external connection terminal 6 are connected by the wiring portion 312, respectively. The wiring portions 309, 310, 311 and 312 are formed of the same ferromagnetic thin film as the magnetic detectors M5 to M12 and have a line width of about 10 μm.

The magnetic detectors M5, M6, M7 and M8 are formed apart from each other by the magnetic pole forming width P of the scale portion 7, and
The magnetic detectors M9, M10, M11, M12 are also formed apart from each other by the magnetic pole formation width P of the scale portion 7. First magnetic detection group 10 including magnetic detectors M5, M6, M7, M8, and magnetic detectors M9, M10, M11, M
The second magnetic detection group 11 having 12 is formed with a phase shift of substantially P / 2.

In the first magnetic detection group 10, the wiring portion 3
09 and the wiring portion 310 are substantially out of phase with each other by the magnetic pole formation width P, that is, separated by m times the magnetic pole formation width P (where m = 1, 3, 5, ...). It is formed in the open state. In the present embodiment, the magnetic pole formation width P
Are formed apart from each other by three times. Similarly, the second
Also in the magnetic detection group 11 of FIG.
12 is formed in a state in which the phase is substantially shifted by the magnetic pole forming width P (in the present embodiment, the state is separated by an interval of three times the magnetic pole forming width P).

The magnetic detector M5 and the wiring portion 309 are substantially in phase with each other or are out of phase with each other by the magnetic pole formation width P, that is, n times the magnetic pole formation width P (however, n).
= 0,1,2,3, ...). In this embodiment, they are formed at the same position. Similarly, the magnetic detector M9 and the wiring portion 311 are also formed in substantially the same phase or in a state in which the phases are shifted by the magnetic pole formation width P (in the present embodiment, at the same position).

As described above, in the third embodiment of the present invention, since the magnetic detector is formed in one line, the range in which the magnetic field is integrated is the line width of the magnetic detector. Therefore, a magnet having a smaller magnetic pole formation width can be used.

Since the number of magnetic detectors is large, the error near the boundary between the adjacent N and S magnetic poles can be further corrected.

Further, since the wiring portion and the magnetic detector have the same line width and are arranged in the same phase, different sine waves are not superposed and an output waveform without waveform distortion can be obtained.

[0036]

As is apparent from the above description, according to the present invention, the error component of the position information due to the magnetoresistive effect of the wiring portion can be removed, and the highly accurate position information can be obtained.

[Brief description of drawings]

FIG. 1 is a formation pattern diagram of an MR element according to a first embodiment of the present invention.

FIG. 2 is a formation pattern diagram of an MR element according to a second embodiment of the present invention.

FIG. 3 is a formation pattern diagram of an MR element according to a third embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram of the MR element of the third embodiment of the present invention.

FIG. 5 is a pattern diagram of a conventional MR element.

FIG. 6 is an equivalent circuit diagram of a conventional MR element.

FIG. 7 is a diagram showing a relationship between each magnetic detector of the MR element and a magnetic pole in the magnet and an output signal waveform of the MR element.

FIG. 8 is a diagram showing an example of a change in resistance value of the MR element when a magnetic field is applied in a direction orthogonal to the MR element.

[Explanation of symbols]

 2 connection wire 4 external connection terminal 5 external connection terminal 6 external connection terminal 7 scale part (magnet) 301 wiring part 302 wiring part 303 wiring part 304 wiring part M1 magnetic detector M2 magnetic detector M3 magnetic detector M4 magnetic detector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G11B 5/39 H01L 43/08 P

Claims (6)

[Claims] 1. A magnetic pole is formed substantially by a scale portion having magnetic poles alternately magnetized at predetermined intervals, and at least one magnetic detector whose resistance value changes in response to a magnetic field in the scale portion. A magnetic detection group arranged at the same distance as the width is formed, and the magnetic detection groups are arranged in pairs at a distance substantially half the magnetic pole formation width. A position detecting device having a sensor unit configured such that a voltage is applied to both ends of the series connection thereof and an output is obtained from a midpoint, the sensor unit being necessary for voltage application and signal output. Of the wiring parts, the wiring part in the direction orthogonal to the magnetic field in the scale part is composed of a wiring group composed of a plurality of wiring parts, and is formed at a distance substantially the same as the magnetic pole formation width for each magnetic detection group. A pair of wiring groups are placed Position detecting apparatus characterized by being. 2. The position detecting device according to claim 1, wherein the magnetic detector and the wiring portion are formed of a ferromagnetic thin film. 3. The magnetic detector according to claim 1 or 2, wherein the positional relationship between the magnetic detectors belonging to the magnetic detection group and the wiring portion in the direction orthogonal to the magnetic field in the scale portion is n times the magnetic pole formation width P of the scale portion ( A position detecting device, wherein the position detecting device is formed with a space of n = 0, 1, 2, ... 4. At least one magnetic detector whose resistance value changes in response to a magnetic field in a scale portion having magnetic poles alternately magnetized at predetermined intervals has a distance substantially equal to the width of the magnetic pole formation. The magnetic detection groups arranged apart from each other are arranged in pairs, and the magnetic detection groups are arranged in pairs at a distance of substantially half the magnetic pole formation width, and both ends of the series connection of the pair of magnetic detection groups. A magnetoresistive effect element configured such that a voltage is applied to the output and an output is obtained from a midpoint.
A wiring portion in the direction orthogonal to the magnetic field in the scale portion is formed of a wiring group including a plurality of wiring portions, and a pair of wiring lines is formed for each magnetic detection group at a distance substantially the same as the magnetic pole formation width. A magnetoresistive effect element characterized in that a wiring group is arranged. 5. The magnetoresistive effect element according to claim 4, wherein the magnetic detector and the wiring portion are formed of a ferromagnetic thin film. 6. The positional relationship between the magnetic detectors belonging to the magnetic detection group and the wiring portion in the direction orthogonal to the magnetic field in the scale portion is n times the magnetic pole formation width P of the scale portion (claim 6). A magnetoresistive effect element, characterized in that the magnetoresistive effect elements are formed with a spacing of n = 0, 1, 2 ,.