JPH10318705A - Position detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a position detecting apparatus which is manufactured easily and whose reliability is high, by a method wherein, while a detecting head is constituted of a plurality of MR elements, connections across the plurality of MR elements are not crossed. SOLUTION: A position detecting apparatus detects a relative position between a magnetic scale 1, on which N-poles and S-poles are repeated and on which graduations are magnetically recorded at an identical pitch, and a detecting head which uses a magnetoresistive element. In the detecting head, two sets 20 to 23, 24 to 27 which are composed of a plurality of magnetoresistive element groups in the recording direction of the graduations on the magnetic scale 1 are arranged at intervals of (n/2-1/4) λ. The plurality of magnetoresistive element groups 20 to 23, 24 to 27 are arranged in the recording direction of the graduations on the magnetic scale 1 at intervals of (n+2) λ. The magnetoresistive element groups are composed of a series circuit by at least two magnetoresistive elements 20a, 20d,...27a, 27d constituting one arm of a bridge circuit and of a series circuit, by at least two magnetoresistive elements 20b, 20c,...27b, 27c constituting the other arm of the bridge circuit.

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 suitable for detecting a position of, for example, a machine tool.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 5, an N pole and an S pole repeatedly have the same pitch λ.
(Λ is the distance between the N pole and the S pole), a magnetic scale 1 on which a scale is magnetically recorded, and a magnetoresistive element (MR element)
There has been proposed a position detecting device which detects a relative position with respect to the detecting head 2 using the method.

As an example of a basic detection head 2 using this conventional MR element, as shown in FIG. 6A, two MR elements 3a arranged at a distance of λ / 2 in the recording direction of the scale of the magnetic scale 1 are used. And 3b are connected in series, and this MR element 3
DC voltage V _O is supplied from the open end 4a of
The open end 4b of the element 3b is grounded, and the output terminal 5a is led out from the connection point between the MR elements 3a and 3b.

In addition, two MR elements 6a and 6a arranged at a distance of λ / 2 in the recording direction of the scale of the magnetic scale 1 are provided.
b are connected in series, the series voltage V _O is supplied from the open end 7a of the MR element 6a, the open end of the MR element 6b is grounded, and the output terminal 5b is led out from the midpoint of connection between the MR elements 6a and 6b. .

In this case, adjacent MR elements 3b and 6b
Are arranged at a distance of λ / 4 in the recording direction of the scale of the magnetic scale 1 so that two-phase outputs having a phase shift of 90 degrees (λ / 4) are obtained at the output terminals 5a and 5b.

The magnetic scale 1 and the MR elements 3a, 3
Since the output signals obtained at the output terminals 5a and 5b are generally small due to the relative displacement with respect to the detection head 2 consisting of b, 6a, and 6b, the output signals having 90 degrees different phases by using output circuits as shown in FIG. 7A. Phase sinusoidal signal, ie, sin
And cos signals.

The output terminal 5a will be described with reference to FIG.
(Or 5b) is connected to the inverting input terminal of the operational amplifier circuit 11 via the resistor 10, and the power supply terminal 12 to which the DC voltage V _O is supplied is connected to the magnetoresistive elements 3a, 3b (6a,
6b) Two resistors 1 having a resistance value determined according to the resistance value
3 and 14 are connected to ground, and this resistor 13
And 14 are connected via a resistor 15 to the non-inverting input terminal + of the operational amplifier circuit 11.

An output terminal 16 is derived from the output side of the operational amplifier circuit 11, and a resistor 17 is connected between the output side of the operational amplifier circuit 11 and the inverting input terminal of the operational amplifier circuit 11. The resistors 10, 15, and 17 constitute a differential amplifier circuit.

The magnetoresistive elements 3a, 3b
(6a, 6b) and the resistors 13, 14 constitute a bridge circuit.

As another example of a basic detection head 2 using a conventional MR element, as shown in FIG. 6B, four MRs are separated by λ / 2 in the recording direction of the scale of the magnetic scale 1.
Elements 3a, 3b, 3d and 3c are arranged, MR elements 3a and 3b are connected in series, and MR elements 3c and 3d are connected in series. DC voltage V is applied to open ends 4a and 4c of MR elements 3a and 3c, respectively. Supply _O and MR element 3
The open ends 4b and 4d of b and 3d are grounded, respectively.

An output terminal 5a is derived from a connection point between the MR elements 3a and 3b, and an output terminal 5c is derived from a connection point between the MR elements 3c and 3d. In this case, the output terminal 5a
5c have output signals 180 degrees out of phase with each other.

The four MR elements 6a, 6b, 6d, 6c are separated by λ / 2 in the recording direction of the scale of the magnetic scale 1.
Are arranged, the MR elements 6a and 6b are connected in series, and the MR elements 6c and 6d are connected in series.
DC voltage V is applied to each of the open ends 7a and 7c.
_O is supplied and the open ends 7b and 7d of the MR elements 6b and 6d are grounded, respectively.

An output terminal 5b is derived from a connection point between the MR elements 6a and 6b, and an output terminal 5d is derived from a connection point between the MR elements 6c and 6d. In this case, output signals whose phases are different from each other by 180 degrees are obtained at the output terminals 5b and 5d.

In this case, the adjacent MR elements 3c and 6a
Are arranged at a distance of λ / 4 in the recording direction of the scale of the magnetic scale 1, and the output terminals 5a and 5b and the output terminals 5c and 5d
To obtain two-phase outputs having different phases by 90 degrees (λ / 4).

When the detecting head 2 as shown in FIG. 6B is used, an output circuit as shown in FIG. 7B is used. 7B, parts corresponding to those in FIG. 7A are denoted by the same reference numerals. The output terminal 5a (or 5b) is connected via a resistor 10 to the inverting input terminal-of an operational amplifier circuit 11 constituting a differential amplifier circuit, and the output terminal 5c (or 5d) is connected via a resistor 15. , Is connected to the non-inverting input terminal + of the operational amplifier circuit 11.

In this case, the magnetoresistive elements 3a, 3
b, 3c and 3d (6a, 6b, 6c and 6d) constitute a bridge circuit, and output terminals 5a and 5c
At (5b and 5d), output signals whose phases are different from each other by 180 degrees are obtained. Therefore, an output signal having a magnitude twice as large as that of the output circuit of FIG. 7A is obtained at the output terminal 16. Also in this case, two-phase sine wave signals having phases different by 90 degrees, ie, si
Signals of n and cos can be obtained.

By processing the sin and cos signals, it is possible to (1) discriminate the relative movement direction and (2) interpolate the recording pitch (electrically divide it to increase the resolution).

The magnetic scale 1 of the position detecting device as described above
In order to accurately detect the scale of magnetic recording described above, the following conditions are required. (1) The scale is magnetically recorded at an accurate pitch λ. (2) The output signal waveform is a sine wave without distortion. (3) The output voltages of sin and cos are the same over the entire detection range. (4) The output signals of sin and cos have no fluctuation of the DC component.

For "(1) The magnetic scale is recorded at an accurate pitch [lambda]", magnetic recording is performed with high precision and the detection head 2 is composed of a plurality of MR elements. By arranging the elements at the same condition position with respect to the scale of the magnetic scale 1 and connecting them in series or in series or in parallel, even if an error occurs in the pitch of the scale of magnetic recording,
The error is averaged by detecting with the plurality of MR elements, and the detection can be performed with high accuracy.

In consideration of the above points, the MR elements 3a, 3b, 6a and 6b of the detection head 2 shown in FIG.
R element 3a-1, 3a-2 {3a-4, 3b-1}
3b-4, 6a-1 @ 6a-4 and 6b-1 @ 6b
FIG. 8 shows an example in which -4 are connected in series.

In this case, the MR elements 3a, 3a of FIG.
3b, 6a and four MR elements 3a respectively constituting 6b
-1, 3a-2, 3a-3, 3a-4, MR element 3b-
1, 3b-2, 3b-3.3b-4, MR element 6b-
4, 6b-3, 6b-2, 6b-1, MR element 6a-
The magnetic scales 4, 6a-3, 6a-2, 6a-1 are arranged at a distance of λ from each other in the recording direction of the scale of the magnetic scale 1.

At this time, the MR elements 3a-1 of each group
{3a-4,3b-1} 3b-4,6b-4} 6
b-1, 6a-4 ‥‥ 6a-1 receive the same change in resistance value by the recording magnetism corresponding to each position of the magnetic scale 1, and as a result, errors are averaged and can be accurately detected.

In FIG. 8, adjacent MR elements 3a-
4 and 3b-1 and MR elements 6b-1 and 6a-4
In the recording direction of the scale of the magnetic scale 1 respectively.
2 away from each other and adjacent MR elements 3b-4 and 6b
-4 in the recording direction of the scale of the magnetic scale 1
4 away.

In FIG. 8, a DC voltage V is applied to the open ends 4a and 7a of the MR elements 3a-1 and 6a-1, respectively.
_O , and the open ends 4b and 7b of the MR elements 3b-4 and 6b-4 are grounded, respectively.
The output terminal 5a is derived from the connection point of the MR elements 6a-4 and 6b-1, and the output terminal 5b is derived from the connection point of the MR elements 6a-4 and 6b-1.

FIG. 9 shows an equivalent circuit of the detection head 2 shown in FIG.
A and B.

The center distance between the MR elements 3a and 3b and the center distance between the MR elements 6a and 6b in FIG.
/ 2, and the group of the MR elements 3a and 3b and the MR
The center-to-center spacing between the groups of the elements 6a and 6b was 3λ / 4, but in the example of FIG. 8, the MR elements 3a-1 ‥‥ 3a-
The center-to-center spacing between the group No. 4 and the group of 3b-1 @ 3b-4 and the center-to-center spacing between the group of MR elements 6a-1 @ 6a-4 and the group of 6b-1 @ 6b-4 respectively. (3 + 1/2) λ, and the MR element 3a-1 ‥‥
The center-to-center spacing between the group of 3a-4, 3b-1 @ 3b-4 and the group of MR elements 6a-1 @ 6a-4, 6b-1 @ 6b-4 is (6 + 3/4) λ. This FIG.
In the example, the interval is increasing. That is, in the example of FIG. 8, the center-to-center spacing increases as the number of MR elements increases.

Incidentally, this MR element is a resistor,
During operation, heat is generated by the supplied current.
a-1 ‥‥ 3a-4 group and 3b-1 ‥‥ 3b-4
And the MR element 6a-1 ‥‥ 6a
When the center-to-center distance between the group of -4 group and the group of 6b-1 ‥‥ 6b-4 is large, unevenness in temperature distribution between the MR element groups due to heat generation or the like occurs. Occurs, and the DC component of the output signal fluctuates, so that the condition (4) that “the output signals of sin and cos do not fluctuate the DC component” cannot be satisfied.

The MR elements 3a-1 @ 3a-4, 3b
-1 @ 3b-4 group and MR element 6a-1 @ 6
When the center-to-center spacing with the group of a-4, 6b-1 ‥‥ 6b-4 increases, the detection position of the magnetic scale 1 moves away.
There is a disadvantage that it is difficult to satisfy that the output voltages of the n and cos signals are the same.

M for detecting the scale of magnetic recording with high accuracy
The following items are required for the detection head 2 using the R element. (1) Increase the number of MR elements. (2) MR element 3a-1 ‥‥ 3a-4 group and 3b
-1 ‥‥ 3b-4 center-to-center spacing and MR element 6a-1 ‥‥ 6a-4 group and 6b-1 ‥‥ 6b
The distance between centers with the group of −4 is made closer (ideal ideal value = λ / 2). (3) MR element 3a-1 @ 3a-4, 3b-1 @ 3
b-4 group and MR elements 6a-1 ‥‥ 6a-4,6
Close the center-to-center spacing with the group of b-1 ‥‥ 6b-4 (ideal closeness ideal value = λ / 4).

As a conventional example which satisfies the above-mentioned requirements, see
No. -11358 has been proposed. The conventional example is 8
The above requirement is satisfied by directly arranging the MR elements in parallel, but the configuration is such that the pattern of the MR element for obtaining the cos output signal is inserted between the patterns of the MR element for obtaining the sin output signal, Naturally, there is an inconvenience that the number of intersections of the connections between the MR elements is large.

That is, as a method of forming a crossing of the connection of the MR element on the substrate, a method of forming a two-phase structure via an insulator, a method of forming a through hole and connecting the back side, and a method of forming a land and connecting the land In any case, there is a problem that the configuration is complicated and expensive, and there is a problem that care must be taken in quality control.

In view of the above, according to the present invention, while the detection head is composed of a plurality of MR elements, the connection between the plurality of MR elements is prevented from intersecting, thereby facilitating manufacture and improving reliability. It is an object to provide a high position detecting device.

[0033]

According to the present invention, the position detecting device comprises an N
The relative position between the magnetic scale on which the scale is magnetically recorded at the same pitch λ (where λ is the interval between the N pole and the S pole) and the detection head using a magnetoresistive element is detected. In such a position detecting device, the distance between the detection heads is (n / 2−1 / 4) λ (n is 1, 2, 3).
Are separated from each other by two sets of a plurality of groups of a plurality of magnetoresistive elements in the recording direction of the scale of the magnetic scale.
+2) λ (n is a natural number of 1, 2, 3 °) spaced apart in the recording direction of the scale of the magnetic scale, and the magnetoresistive effect element group comprises at least two magnetic fields forming one side of a bridge circuit. The bridge circuit comprises a series circuit of a resistance effect element and a series circuit of at least two magnetoresistive elements forming the other side of the bridge circuit.

According to the present invention, a plurality of MR elements constituting one side of the bridge circuit and a plurality of M elements constituting the other side are provided.
A plurality of Ms that can set the interval with the R element to, for example, λ / 2 and obtain two-phase sine wave signals having a phase difference of 90 degrees.
The distance between the R elements can be set to, for example, (2 + ／) λ, and highly reliable position detection can be performed.
The connection between the R elements can be prevented from crossing, and the manufacturing can be facilitated.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a position detecting device according to the present invention will be described below with reference to FIGS.
As shown in FIG. 5, the position detecting device of this example also has a magnetic scale 1 on which scales are magnetically recorded at the same pitch [lambda] ([lambda] is an interval between the N pole and the S pole). The relative position with respect to the detection head 2 using a magnetoresistive element (MR element) whose resistance value changes is detected. In this example, the detection head 2 is configured as shown in FIG. .

FIG. 1 shows an example in which a plurality of, for example, four MR element groups 20, 2 arranged in the recording direction of the scale of the magnetic scale 1.
Two sets of one set consisting of 1, 2, 23 and another set consisting of a plurality of, for example, four MR element groups 24, 25, 26, 27 arranged in the recording direction of the scale of the magnetic scale 1;
In the recording direction of the scale of the magnetic scale 1, the distance between the two sets is (n / 2-1/4) λ (n is a natural number of 1, 2, 3). I will do it.

The MR element groups 20, 21 ‥‥ 27 are composed of four MR elements 20a, 20b, 20c, 20d, 21a, 21a arranged along the recording direction of the scale of the magnetic scale 1.
21b, 21c, 21d ‥‥ 27a, 27b, 27c,
27d, and the respective MR element groups 20, 21 ‥‥ 2
7, the distance between the MR elements 20a, 21a ‥‥ 27a and the MR elements 20b, 21b ‥‥ 27b is
Λ / 2 in the recording direction of the scale
21b ‥‥ 27b and MR elements 20c, 21c ‥‥ 27c
Are defined as λ in the recording direction of the scale of the magnetic scale 1, respectively, and the MR elements 20c, 21c ‥‥ 27c and the MR element 20c
The distance between d and 21d ‥‥ 27d is λ / 2 in the recording direction of the scale of the magnetic scale 1 respectively.

In this case, the respective MR elements 20, 21,.
27, the MR elements 20a, 201a ‥‥ 27a and M
Since the R elements 20d, 21d ‥‥ 27d are separated by 2λ in the recording direction of the scale of the magnetic scale 1, the same resistance value change is caused by the recording magnetic field of the magnetic scale 1, and the respective MR element groups 20, 21 # 27 MR element 2
0b, 21b {27b and MR elements 20c, 21c}
27c is separated from the magnetic scale 1 by an interval λ in the recording direction of the graduations, so that the recording magnetic field of the magnetic scale 1 receives the same resistance value change.

The distance between the MR element 20d of the MR element group 20 and the MR element 21a of the MR element group 21, the distance between the MR element 21d of the MR element group 21 and the MR element 22a of the MR element group 22, MR element 22d and MR element group 2
3, the distance between the MR element 24a of the MR element group 24 and the MR element 25a of the MR element group 25,
MR element 25d of MR element group 25 and M of MR element group 26
The distance from the R element 26a and the MR element 2 of the MR element group 26
The distance between 6d and the MR element 27a of the MR element group 27 is mλ (m is an integer of 3 or more) in the recording direction of the scale of the magnetic scale 1, and is 3λ in this example.

In this embodiment, the MR element groups 20, 21
# 27 is applied to the MR element groups 20, 24, 21, 25, 22, 26, from left to right of the magnetic scale 1 as shown in FIG.
Arranged in the order of 23 and 27, the MR element 2 of the MR element group 20
0d and the distance between MR element 24a of MR element group 24, MR
The distance between the MR element 21d of the element group 21 and the MR element 25a of the MR element group 25, the distance between the MR element 22d of the MR element group 22 and the MR element 26a of the MR element group 26, and the distance between the MR element 23d of the MR element group 23 MR element 2 of MR element group 27
The distance from the reference numeral 7a is (n / 2-１ ／) λ (n is 1, 2, 3 ‥‥ natural number) in the recording direction of the scale of the magnetic scale 1, and is λ / 4 in this example.

Accordingly, in this embodiment, the distance between the MR element 24d of the MR element group 24 and the MR element 21a of the MR element group 21, M
The MR element 25d of the R element group 25 and the MR of the MR element group 22
The distance from the element 22a and the MR element 26 of the MR element group 26
The distance between d and the MR element 23a of the MR element group 23 is 3λ / 4 in the recording direction of the scale of the magnetic scale 1 respectively.

In this embodiment, the MR elements 20a, 2
0d, 21a, 21d, 22a, 22d, 23a, 23
d, 23c, 23b, 22c, 22b, 21c, 21
b, 20c and 20b are connected in series in this order, a DC voltage V _O is supplied to the open end 28a of the MR element 20a, and the open end 28b of the MR element 20b is grounded.
An output terminal 29a is derived from a connection point between 3c and 23d.

In this case, the MR elements 20a, 20b #
The equivalent circuit of # 23d is as shown in FIG. 2A, and the MR elements 20a, 20d, 21a, 21d, 22a, 22d, 2
The series circuit of 3a and 23d forms one side of the bridge circuit of FIG. 7A, and the MR elements 23c, 23b, 22c, 22
The series circuit of b, 21c, 21b, 20c and 20b constitutes another side of the bridge circuit of FIG. 7A.

The MR elements 24a, 24d, 25
a, 25d, 26a, 26d, 27a, 27d, 27
c, 27b, 26c, 26b, 25c, 25b, 24c
And 24b are connected in series in this order, a DC voltage V _O is supplied to the open end 30a of the MR element 24a, and the open end 30b of the MR element 24b is grounded.
The output terminal 29b is derived from the connection point 7d.

In this case, the MR elements 24a, 24b #
The equivalent circuit of # 27d is as shown in FIG.
4a, 24d, 25a, 25d, 26a, 26d, 27
7A constitute one side of the bridge circuit of FIG. 7A, and the MR elements 27c, 27b, 26c, 26
The series circuit of b, 25c, 25b, 24c and 24b constitutes another side of the bridge circuit of FIG. 7A.

In this case, the MR elements 20a, 20b # 2
The connection between the 3d and the MR elements 24a, 24b ‥‥ 27d should be made without crossing each other and the open ends 28a, 2
8b, 30a, 30b and output terminals 29a, 29b are drawn out from one direction (downward in FIG. 1).

The distance between one set of the MR element groups 20, 21, 22, 23 and the other set of the MR element groups 24, 25, 26, 27 is set to λ / 4, the output terminals 29a and 29b
, Two-phase sine wave signals having different phases by 90 degrees (λ / 4), that is, signals of sin and cos are obtained.

Also in this example, the magnetic scales 1 and M
The output signals obtained at the output terminals 29a and 29b by the relative displacement with respect to the detection head 2 composed of the R element are shown in FIG.
Are used to obtain two-phase sine wave signals having a phase difference of 90 degrees, ie, sin and cos signals.

According to this embodiment, the eight MR elements 20a, 20d, 21a, 21d,
22a, 22d, 23a, 23d (or 24a, 24
d, 25a, 25d, 26a, 26d, 27a, 27
d) and eight MR elements 23c and 23 forming other sides
b, 22c, 22b, 21c, 21b, 20c, 20b
(Or 27c, 27b, 26c, 26b, 25c, 25
b, 24c, 24b) can be set to λ / 2, and a set of 16 MR elements 20a, 20b ‥‥ 23d, each of which obtains a two-phase sine wave signal having a phase difference of 90 °, and an MR The interval between the elements 24a and 24b ‥‥ 27d and the other set can be set to (2 + ／) λ, and there is an advantage that highly reliable position detection can be performed.

According to the present embodiment, the 32 MR elements 20
The connection between a, 20b and 27d can be made without crossing, and the connection can be made simultaneously with this MR element using the same material as this MR element, which has the advantage of facilitating manufacture. .

FIGS. 3 and 4 show another embodiment of the present invention. 3 and 4, parts corresponding to those in FIGS. 1 and 2 are denoted by the same reference numerals. In the example of FIG. 3, the arrangement of the MR elements 20a, 20b ‥‥ 27d is shown in FIG.
The example is the same as the example, and the connection is different from the example in FIG. Therefore, here, the MR elements 20a, 20b
The description of the arrangement of # 27d is omitted, and the connection is described.

In this embodiment, the MR elements 20a, 20a
0d, 21a, 21d, 22a, 22d, 23a and 2
3d are connected in series in this order, and the MR elements 20a and 23
DC voltage V _o at each of the open ends 28a and 28c of FIG.
And an output terminal 29a is derived from a connection point between the MR elements 21d and 22a.

The MR elements 20b, 20c, 21b and 21c are connected to the output terminal 29a as a series circuit in this order, and the MR elements 23c, 23b, 22c and 22b are connected.
Are connected to the output terminal 29a as a series circuit in this order, and the open ends 28b and 28d of the MR elements 20b and 23c are connected.
Are grounded respectively.

In this case, the MR elements 20a, 20b # 2
As shown in FIG. 4A, the equivalent circuit of 3d is the MR element 20a,
Series circuit of 20d, 21a and 21d and MR element 23
d, 23a, 22d and 22a constitute one side of the bridge circuit of FIG.
A parallel circuit of a series circuit of 1c, 21b, 20c and 20b and a series circuit of MR elements 22b, 22c, 23b and 23c constitutes another side of the bridge circuit of FIG. 7A.

The MR elements 24a, 24d, 25
a, 25d, 26a, 26 d, to connect the 27a and 27d in this order in series, the connection point of the MR elements 25d and 26a supplies the respective DC voltage V _o to the MR elements 24a and open ends 30a and 30c of each of 27d Then, the output terminal 29b is derived.

The MR elements 24b, 24c, 25b and 25c are connected to the output terminal 29b as a series circuit in this order, and the MR elements 27c, 27b, 26c and 26b
Are connected to the output terminal 29b as a series circuit in this order, and the open ends 30b and 30d of the MR elements 24b and 27c are connected.
Are grounded respectively.

In this case, the MR elements 24a, 24b # 2
As shown in FIG. 4B, the equivalent circuit of 7d is the MR element 24a,
Series circuit of 24d, 25a and 25d and MR element 27
d, 27a, 26d and a parallel circuit with the series circuit constitute one side of the bridge circuit of FIG.
A parallel circuit of a series circuit of 5c, 25b, 24c and 24b and a series circuit of MR elements 26b, 26c, 27b and 27c constitutes another side of the bridge circuit of FIG. 7A.

In this case, the MR elements 20a, 20b # 23
d and the MR elements 24a, 24b ‥‥ 27d are connected without crossing each other and open ends 28a, 28
b, 28c, 28d, 30a, 30b, 30c, 30d
And output terminals 29a, 29b in one direction (downward in FIG. 3)
So as to draw more out.

It can be easily understood that the same effects as those of the example of FIG. 1 can be obtained in the example of FIG. In the example of FIG. 3, since the MR elements are connected in series and in parallel,
There is an advantage that the total resistance of the element can be reduced and power can be saved.

Further, as shown in FIG. 1 or FIG.
Are arranged in the recording direction of the scale of the magnetic scale 1 at an interval of (n + ／) λ (n is an integer of 0, 1, 2, 3}), and output signals are in opposite phases (phases). Are different by 180 degrees), and the output circuit shown in FIG. 7B may be used.

At this time, there is an advantage that a stable and large output signal can be obtained as a two-phase signal having a phase difference of 90 degrees.

Incidentally, in the example of FIG. 1 and FIG.
Although it has been described that the DC voltage V _O is supplied to 8a, 28c, 30a, and 30c and the open ends 28b, 28d, 30b, and 30d are grounded, the open ends 28a, 28c, 30a, and 30c
May be grounded to supply a DC voltage V _O to the open ends 28b, 28d, 30b, 30d. 2 at this time
The phase output signal has a phase difference of 270 degrees, but is characteristically the same as described above.

The present invention is not limited to the above-described embodiment.
It goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0064]

According to the present invention, a plurality of MR elements constituting one side of the bridge circuit and a plurality of MRs constituting the other side are provided.
A plurality of MRs that can set the interval with the element to, for example, λ / 2 and obtain two-phase sine-wave signals having a phase difference of 90 degrees
The distance between the elements can be set to, for example, (2 + λ) λ, the position can be detected with high reliability, and the connection between the MR elements can be performed without crossing.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a position detection device of the present invention.

FIG. 2 is a connection diagram illustrating an equivalent circuit of the detection head of FIG. 1;

FIG. 3 is a configuration diagram showing another example of the position detection device of the present invention.

FIG. 4 is a connection diagram illustrating an equivalent circuit of the detection head of FIG. 3;

FIG. 5 is a perspective view illustrating an example of a position detection device.

FIG. 6 is a configuration diagram illustrating an example of a conventional position detection device.

FIG. 7 is a connection diagram illustrating an example of an output circuit.

FIG. 8 is a configuration diagram illustrating an example of a conventional position detection device.

9 is a connection diagram illustrating an equivalent circuit of the detection head in FIG.

[Explanation of symbols]

20, 21, 22, 23, 24, 25, 26, 27 M
R element group, 20a, 20b ‥‥ 27d MR element, 28
a, 28b, 28c, 28d, 30a, 30b, 30
c, 30d open end, 29a, 29b output terminal

Claims (2)

[Claims] 1. An N-pole and an S-pole repeatedly having the same pitch λ (λ
A distance between a north pole and a south pole), and a position detecting device for detecting a relative position between a magnetic scale on which a scale is magnetically recorded and a detection head using a magnetoresistive element. Two sets each including a plurality of magnetoresistive element groups in the recording direction of the scale of the magnetic scale at an interval of (n / 2−1 / 4) λ (n is a natural number of 1, 2, 3 °). The plurality of magnetoresistive element groups are arranged in the recording direction of the scale of the magnetic scale at an interval of (n + 2) λ (n is a natural number of 1, 2, 3 °). The effect element group includes a series circuit of at least two magnetoresistive elements forming one side of the bridge circuit and a series circuit of at least two magnetoresistive elements forming the other side of the bridge circuit. Position detecting device. 2. The position detecting device according to claim 1, wherein the distance between the detection heads is (n + ／) λ (n is 0,
2. A position detecting device, wherein two magnetic scales are arranged in the recording direction of the scale of the magnetic scale at a distance from each other (an integer of 1, 2, 3).