JPH0882532A - Magnetic field detecting head and position detector - Google Patents

Abstract

PURPOSE: To improve the drift and the amplitude fluctuation of a detected voltage. CONSTITUTION: A first magnetoresistance effect element 12, a bias conducting film 13 and a second magnetoresistance-effect element 14 are laminated and formed sequentially on a substrate through insulating layers 11a, 11b and 11c. A specified bias current is made to flow through the biasing conductive film 13. Bias magnetic fields in the reverse directions to each other are applied on the first and second magnetoresistance-effect elements 12 and 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field detection head and position detection device suitable for use in, for example, magnetic scales, rotary encoders, etc., applied to machine tools, industrial machines, precision measuring and angle measuring devices, etc. Regarding

[0002]

2. Description of the Related Art Conventionally, machine tools, industrial machines, precision length measurement,
As a magnetic field detection head for position detection devices such as magnetic scales and rotary encoders applied to angle measuring devices,
Magnetoresistive effect element (MR element) utilizing the magnetoresistive effect of a thin film of Fe-Ni (permalloy), Ni-Co, etc.
Is used.

As a position detecting device to which a magnetic field detecting head using such an MR element is applied, for example, a structure as shown in FIG. 13 is adopted.

That is, in FIG. 13, reference numeral 1 denotes a magnetic scale. This magnetic scale 1 is a magnetic recording medium in which a magnetic material is deposited by electroless plating on a surface of a glass base material having a rectangular cross section by 2 to 3 μm. This magnetic recording medium is used with an ordinary magnetic recording head with a constant wavelength λ, for example, 4 in the longitudinal direction.
The scale 1a is recorded at 0 μm.

The magnetic field detecting head 2 is provided so as to move relative to the magnetic scale 1 in the longitudinal direction thereof. The magnetic field detection head 2 is held by a holding mechanism (not shown) so that its detection surface keeps a constant distance from the magnetic scale 1 and is relatively displaced in the longitudinal direction of the magnetic scale 1.

By the way, the resistance value-magnetic field characteristic of such an MR element is as shown by the curve a in FIG. 14, and in the magnetic field detection head 2 using this MR element, in order to realize high precision and high resolution, this MR element is used. Bias magnetic field such as Hb
Is applied to act as a bias point at the point b having a good linearity of the curve a, and the bridge structure as shown in FIGS. 15 and 16 is adopted in order to compensate the temperature characteristic of the MR element.

This magnetic field detection head 2 is shown in FIG.
As shown in the formula, four MR elements R ₁, R₂, R₃as well as
R_FourTo form. That is, four MR elements R₁, R₂,
R₃, R _FourAre sequentially arranged along the longitudinal direction of the magnetic scale 1.
And MR element R₁And R₂Interval with and R₃And R_Four
And the recording wavelength λ of the magnetic scale 1,
MR element R₂And R₃And the distance between and is λ / 4
It

A predetermined positive voltage + V is supplied to one end of each of the MR elements R ₁ and R ₃ and the MR elements R ₂ and R 3 are
₄ supplies a predetermined negative voltage -V to one end of each of, the MR element with connecting the MR elements R ₁ and R ₂ each of the other ends to each other, to derive the one detection terminal Vout1 from the connection point R
The other ends of ₃ and R ₄ are connected to each other, and the other detection terminal Vout2 is derived from this connection point.

In this example, the MR elements R ₁ , R ₂ , R
Bias patterns 4 are provided on the upper sides of ₃ and R ₄ via an insulating layer, and bias currents in the same direction are applied to the bias patterns 4 in the directions indicated by arrows in FIG. 16A. The magnitude of this bias current is b in FIG.
A bias magnetic field Hb whose point is a bias point is generated.

The MR element R of the example of FIG.₁, R₂,
R₃, R_FourThe arrangement relationship of R is as shown in FIG. 16A.₁And R₂
Interval with and R₃And R_FourAnd the distance between them is λ / 2,
R₂And R ₃The distance between and is λ / 4.

An equivalent circuit of the magnetic field detecting head 2 is shown in FIG.
MR element R as shown in B₁And R₂Series circuit and MR element
Child R₃And R_FourIs connected in parallel with the series circuit of
Child R ₁And R₂Connection point and MR element R₃And R_FourContact with
One and the other detection terminals Vout1 and Vout2 respectively from the continuation point
Is a bridge configuration derived from. In FIG. 13, 7 is
Provide a bias current and a predetermined operating voltage to the magnetic field detection head 2.
A flexible pre-supply for supplying the detected voltage signal while supplying
It is a wiring board.

In this example, when the magnetic field detection head 2 is moved relative to the magnetic scale 1, the MR element R
The change in the resistance value of each of ₁ , R ₂ , R ₃ and R ₄ is shown in FIG.
MR elements R ₁ and R _{2 as} shown in A, B, C and D.
And the phase difference of the resistance change between R ₃ and R ₄ is 18
0 degree, and detection voltage signals with a 90 degree phase difference are obtained at the detection terminals Vout1 and Vout2 as shown in FIGS. 4E and 4F.
With this detection voltage signal, the relative movement distance between the magnetic scale 1 and the magnetic field detection head 2 can be measured.

In such a conventional example, the MR elements R ₁ , R
₂ , R ₃ and R ₄ form a bridge structure, and the phase difference of the resistance change of each of the MR elements R ₁ and R ₂ and R ₃ and R ₄ is 180 degrees. Even when the changes fluctuate, the fluctuations can be canceled by each other.

[0014]

However, in the magnetic field detecting head 2 as shown in the example of FIG. 15, the phase difference between the resistance changes of the MR elements R ₁ and R ₂ and R ₃ and R ₄ is exactly 180. There is an inconvenience that it is relatively difficult to establish a proper arrangement relationship.

The MR elements R ₁ and R ₂ and R ₃ and R ₄
And λ / 2 in the longitudinal direction of the magnetic scale 1 due to their respective positional relationships.
Displacement and, since the MR element _{R 1, R 2, R 3} , R 4 is a resistor to generate heat by flowing course current, the temperature of itself is able to rise, the MR elements R ₁ and R ₂ , R ₃ and R ₄ are respectively deviated by λ / 2 in the longitudinal direction of the magnetic scale 1, and their respective temperature rises may differ and the magnetic field variation from the magnetic scale 1 may differ. For this reason, the resistance value and the rate of change fluctuate among the MR elements R ₁ , R ₂ , R ₃ , and R ₄ , which causes the drift of the detection voltage and the fluctuation of the amplitude, resulting in the deterioration of high precision and high resolution.

The present invention has been made in view of the above points, and an object thereof is to improve drift and amplitude fluctuation of a detection voltage.

[0017]

A magnetic field detecting head according to the present invention has an insulating layer 11 on a substrate 1 as shown in FIG. 1, for example.
The first magnetoresistive effect element 12, the bias conductive film 13 and the second magnetoresistive effect element 14 are laminated in this order via a, 11b and 11c, and the bias conductive film 1 is formed.
3, a predetermined bias current is made to flow, and bias magnetic fields Hb and -Hb in opposite directions are applied to the first and second magnetoresistive effect elements 12 and 14, respectively.

In the magnetic field detecting head of the present invention, for example, as shown in FIG. 1, the conductor layers 12a and 14a and the magnetic layers 12b and 14b are alternately used as the first and second magnetoresistive effect elements 12 and 14 in the above description. A magnetoresistive effect element having an artificial lattice film structure formed by stacking layers is used.

The position detecting apparatus of the present invention comprises a magnetic recording medium 1 on which magnetic information 1a is recorded as shown in FIGS. 1, 2 and 3.
The magnetic recording medium 1 has a magnetic field detecting section 2 that can change relative to the magnetic recording medium 1 and detects the magnetic information 1a. Based on the detected magnetic information 1a, the magnetic recording medium 1 and the magnetic field detecting section 2 are detected. The above-mentioned magnetic field detection head is used for the magnetic field detection unit 2 at the position detection position where the relative displacement amount or relative movement speed of (1) can be measured.

[0020]

According to the present invention, since the first magnetoresistive effect element 12, the biasing conductive film 13 and the second magnetoresistive effect element 14 are sequentially laminated, a bias current is passed through the biasing conductive film 13. As a result, bias magnetic fields Hb and −Hb having the same magnitude and opposite directions can be applied to the first and second magnetoresistive effect elements 12 and 14, and the first and second magnetic resistance elements can be applied. Resistance effect elements 12 and 14
The phase difference of the change in the resistance value of can be set to 180 degrees as a correct answer, and the first and second magnetoresistive effect elements 12 can be obtained.
Since 14 and 14 are laminated, the temperature rise is the same and the magnetic field received from the magnetic recording medium 1 is the same, the drift of the detection voltage and the amplitude fluctuation can be improved, and the displacement amount or the moving speed can be measured with high accuracy and high resolution.

Further, according to the present invention, the conductor layers 12a and 14 are used as the first and second magnetoresistive effect elements 12 and 14, respectively.
A magnetoresistive effect element (GMR element) having an artificial lattice film structure in which a and magnetic layers 12b and 14b are alternately laminated is used, and this GMR element responds to an externally applied magnetic field as shown by a curve d in FIG. The characteristic of the magnetoresistance change rate is that the resistance change rate is large and has high sensitivity as compared with the conventional MR element such as permalloy, and when this GMR element is used, the clearance between the magnetic recording medium 1 and the magnetic field detection head 2 ( It is possible to obtain a high-precision, high-resolution position detecting device in which the distance) can be increased, the protective film layer can be thickened, or the surface of the GMR element can be protected by a thin plate metal material, and the detection surface is less likely to be damaged.

Further, when this GMR element is used with a clearance equivalent to the clearance in the conventional MR element, the recording wavelength can be further shortened, so that a position detecting device with higher density and higher resolution can be obtained. .

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a magnetic field detecting head and a phase detecting device of the present invention will be described below with reference to the drawings. The position detecting device according to the present example is provided with a magnetic scale as in FIG.

The magnetic scale 1 used as a magnetic recording medium is a glass substrate having a rectangular cross-section and a magnetic substance deposited on the surface by electroless plating by 2 to 3 μm. The scale 1a is recorded in the longitudinal direction at a constant wavelength λ, for example 40 μm.

A magnetic field detecting head 2 is provided so as to move relative to the magnetic scale 1 in the longitudinal direction thereof. The magnetic field detecting head 2 is held by a holding mechanism (not shown) so that its detecting surface keeps a constant distance from the magnetic scale 1 and changes relative to the longitudinal direction of the magnetic scale 1.

In this embodiment, the magnetic field detecting head 2 shown in FIGS. 1, 2 and 3 is used. FIG. 1 is a sectional view of the basic structure of the magnetic field detecting head according to this example. To explain the basic structure of the magnetic field detecting head with reference to FIG. 1, a glass substrate or an aluminum substrate 10 will be described.
An insulating layer 11a made of, for example, SiO ₂ is provided on the upper surface to serve as an insulating substrate.

A magnetic layer such as CoFeNi magnetic alloy such as Fe ₁₈ Co ₁₀ N is formed on the glass substrate or the insulating layer 11a.
i ₇₂ , a layer 12b of Fe ₁₆ Co ₂₀ Ni ₆₄ and a conductor layer such as C
An artificial lattice multilayer film including the u layer 12a is formed using a sputtering device.

In this case, the CoFeNi magnetic alloy layer 12
b has a thickness of 1 nm, and the Cu layers 12a have a thickness of 2.2 nm. The layers are alternately formed into 20 layers to form a magnetoresistive effect element (GMR element) 12 having an artificial lattice film structure.

An insulating layer 11b of, for example, SiO ₂ is provided on the GMR element 12, and the GMR is formed on the insulating layer 11b.
The bias conductive film 13 is formed of, for example, Au so as to be stacked so as to overlap the element 12.

As shown in FIG. 1, an insulating layer 11c made of, for example, SiO ₂ is provided on the bias conductive film 13, and a magnetic layer such as CoFeNi is formed so as to be stacked on the insulating layer 11c so as to overlap the bias conductive film 13. Magnetic alloy layer 14b
An artificial lattice multi-layered film composed of a conductor layer such as a Cu layer 14a is formed by using a sputtering device.

In this case, the CoFeNi magnetic alloy layer 14b has a thickness of 1 nm, and the Cu layer 14a has a thickness of 2.2 nm.
20 layers are alternately formed to form a magnetoresistive effect element (GMR element) 14 having an artificial lattice film structure. A protective film 15 is deposited on the GMR element 14 with a resist or the like as shown in FIG.

The artificial lattice films 12a, 12b, 14a.
14b and the bias conductive film 13 are formed into a strip-shaped pattern of a predetermined size by using a photolithography technique. In this case, the easy axis of magnetization is perpendicular to the direction of relative movement to the magnetization direction (applied magnetic field direction) of the magnetic scale 1 on which the magnetic information 1a detected by the magnetoresistive effect elements 12 and 14 having the artificial lattice film structure is recorded. As it exists.

Further, in FIG. 1, 16 and 18 are lead conductors for supplying a voltage to the GMR elements 12 and 14, respectively.
Reference numeral 7 indicates a lead conductor for supplying a current to the bias conductive film 13.

When a current is applied to the bias conductive film 13 as shown in FIG. 1, the bias conductive film 1 is supplied.
A magnetic field in the direction indicated by the arrow is generated around 3 and the GMR elements 12 and 14 below and above this bias conductive film 13 are formed.
Are respectively bias magnetic fields Hb and −b of the same magnitude in opposite directions.
Hb will be applied.

Therefore, the GMR elements 12 and 14 operate, for example, with the point b in FIG. 14 and the point c symmetrical thereto as the bias points, respectively, and 180 degrees with respect to the change of the external magnetic field as shown in FIG. The resistance changes with the phase reversed.

In this case, the vertical gap between the GMR elements 12 and 14 is 1 μm or less, which is negligible compared to the recording wavelength of the magnetic scale 1.

In this example, as shown schematically in FIG.
The field detecting head 2 is a via configured as shown in FIG.
GMR element R above and below the conductive film 13 for₁(14) and R
₂(12) and the top and bottom of the bias conductive film 13
GMR element R₃(14) and R _FourShaped with (12)
This GMR element R₁And R₃And the magnetic scale 1
1/4 of the recording wavelength λ of the magnetic scale 1 in the longitudinal direction
Arrange them so that they are spaced.

Further, a predetermined positive voltage + V is supplied to one end of each of the GMR elements R ₁ and R ₃ , and a predetermined negative voltage −V is supplied to one end of each of the GMR elements R ₂ and R ₄ to obtain the GMR. The other ends of the elements R ₁ and R ₂ are connected to each other, one detection terminal Vout1 is derived from this connection point, and the other ends of the GMR elements R ₃ and R ₄ are connected to each other. The other detection terminal Vout2 is derived from the point.

In this example, a predetermined current is passed through the two bias conductive films 13, a bias magnetic field Hb is applied to the GMR elements R ₁ and R ₃ as shown in FIG. 14, and operation is performed around the bias point b. In addition, as shown in FIG. 14, a bias magnetic field −Hb having the same magnitude as the bias magnetic field Hb but in the opposite direction is applied to the GMR elements R ₂ and R ₄ , and the bias point c symmetrical to the bias point b is centered. To work.

GMR elements R ₁ , R ₂ , R ₃ , R _{4 of} this example
3A, the GMR elements R ₁ and R ₂ overlap each other as shown in FIG. 3A, and the GMR elements R ₃ and R ₄ overlap each other, and the gap between the GMR elements R ₁ and R ₃ is λ.
/ 4 away.

The equivalent circuit of this magnetic field detection head 2 is shown in FIG. 3B.
As shown in Fig. 3, GMR elements R ₁ and R ₂ are connected in series with G
A bridge configuration in which a series circuit of MR elements R ₃ and R ₄ is connected in parallel, and detection terminals Vout1 and Vout2 are derived from a connection point between GMR elements R ₁ and R ₂ and a connection point between R ₃ and R ₄ , respectively. Is.

In this example, when the magnetic field detection head 2 is moved relative to the magnetic scale 1, this GMR
The change in the resistance value of each of the elements R ₁ , R ₂ , R ₃ and R ₄ is as shown in FIGS. 4A, 4B, 4C and 4D, and the resistance values of the GMR elements R ₁ and R ₂ and R ₃ and R ₄ are changed. The phase difference of the resistance change is 180 degrees, and the detection terminals Vout1 and Vout2 are shown in FIG.
As shown by E and F, a detection voltage signal with a 90-degree phase difference is obtained, and the relative moving distance between the magnetic scale 1 and the magnetic field detection head 2 can be measured by this detection voltage signal.

According to this example, the GMR elements R ₁ , R ₂ ,
R _3, has a bridge configuration and by R _4, the phase difference of each of the change in resistance of the GMR elements R ₁ and R ₂ and R ₃ and R ₄ are each 180 degrees, due to the influence of temperature, etc., the resistance change Even when fluctuates, the fluctuations can be canceled by each other.

In this case, according to this example, the GMR element R
₁ , R ₃ , bias conductive film 13 and GMR element R ₂ ,
Since R ₄ is laminated, a bias current is passed through the bias conductive film 13 so that the GMR elements R ₁ and R _{3 are}
And R _2, can be applied a bias magnetic field Hb and -Hb of one another opposite direction at the same size in R _4, this such GMR elements R _1, R ₃ and R _2, the change in the resistance of R ₄ The phase difference can be exactly 180 degrees and the GMR element R
_{Since 1} , R ₃ and R ₂ , R ₄ are laminated, the temperature rise is equal and the magnetic field received from the magnetic scale 1 is equal, and when the bridge configuration is adopted, a temperature and time stable detection voltage signal can be obtained. It is possible to measure the change amount or the moving speed with high accuracy and high resolution.

Further, even if there is a difference in strength in magnetic recording due to a difference in location in the longitudinal direction of the magnetic scale 1 or unevenness,
Two upper and lower GMR elements R ₁ , R ₃ and R ₂ , R ₄
Since an external magnetic field is applied from the magnetic scale 1 at exactly the same location, this detection voltage signal does not change except for the amplitude fluctuation, and more highly accurate detection can be performed.

Further, according to this example, the GMR elements R ₁ and R ₂ and R ₃ and R ₄ are overlapped with each other, and the GMR elements R ₁ and R ₃ are spaced by λ / 4. Two
Can be miniaturized. In this case, the GMR element R ₁
The distance between R ₃ and R ₃ may be (n ± 1/4) λ.

Further, according to this example, the GMR element R ₁ ,
R ₂ , R ₃ and R ₄ are used, and this GMR element has a characteristic of a magnetoresistance change rate with respect to an externally applied magnetic field as shown by a curve d in FIG. Large and high sensitivity, this GMR
When the element is used, the clearance (spacing) between the magnetic scale 1 and the magnetic field detection head 2 can be increased, the protective film layer can be thickened, or the surface of the GMR element can be protected by a thin metal plate, and the detection surface is not damaged. High precision that is hard to get up,
A high-resolution position detection device can be obtained.

When this GMR element is used with a clearance equivalent to the clearance in the conventional MR element, the recording wavelength of the magnetic scale 1 can be further shortened, so that a position detecting device with higher accuracy and higher resolution can be obtained. be able to.

FIG. 6 shows an example in which the present invention is applied to a rotary encoder. In FIG. 6, reference numeral 21 denotes a rotor, and the magnetic recording medium 2 is provided on the outer circumference of the rotor 21.
2 is provided, and the scale is magnetically recorded on the magnetic recording medium 22 at a predetermined wavelength λ. The magnetic field detection head 2 is arranged so as to face the magnetic recording medium 22 on the outer periphery of the rotor 21.

As shown in FIG. 7, the magnetic field detecting head 2 having the same structure as that of FIGS. 2 and 3 is used.

Generally, a magnetic rotary encoder mechanically adopts a structure in which the outer peripheral surface of the rotor 21 is used as a magnetic recording signal surface as shown in FIG. 6, but in this case, the width of the magnetic field detecting head 2 is widened. If, although the in the center and near the end which is one of causes of deteriorating the accuracy different spacing of the rotor 21 (clearance) is the magnetic field detection head 2 according to this embodiment, GMR elements R ₁ as shown in FIG. 7 And R ₂ are overlapped, and GMR elements R ₃ and R ₄ are also overlapped, and the distance between GMR elements R ₁ and R ₃ can be λ / 4 apart. It is possible to obtain a rotary encoder that outputs a highly accurate detection voltage signal without deterioration of In this case, the GMR element R
The distance between ₁ and R ₃ may be (n ± 1/4) λ.

It can be easily understood that the same effects as those of the above-described embodiment can be obtained also in the examples of FIGS. 6 and 7.

8 and 9 show another embodiment of the present invention. To explain FIG. 8 and FIG. 9, in FIG.
1 indicates a magnetic scale, and this magnetic scale 31 is Cu
A wire having a circular cross section such as a NiFe alloy or a CrCoFe alloy is used, and a constant wavelength λ (for example, 1
The magnetic recording is performed on the scale with a diameter of 00 μm.

On the other hand, in the magnetic field detecting head 32, as shown in FIGS. 8 and 9, a hole 34 having a diameter slightly larger than the outer diameter of the wire material constituting the magnetic scale 31 is formed in the central portion of the glass plate or aluminum substrate 33. Along with this board 33, for example, S
An insulating layer 35a of iO ₂ is provided.

An artificial lattice multi-layered film consisting of a magnetic layer of a predetermined width such as a CoFeNi magnetic alloy layer and a conductor layer such as a Cu layer is formed along the outer periphery of the hole 34 on the insulating layer 35a by using a sputtering apparatus.

In this case, the CoFeNi magnetic alloy layer has a thickness of 1 nm and the Cu layer has a thickness of 2.2 nm, and 20 layers are formed alternately, and a magnetoresistive effect element (GMR element) 36 having an artificial lattice film structure is formed. To form. Also in this case hole 3
There is a slight gap between the outer circumference of the No. 4 and the GMR element 36.

An insulating layer 35b of, for example, SiO ₂ is provided on the GMR element 36, and the hole 34 is formed on the insulating layer 35b.
A bias conductive film 37 is formed of, for example, Au so as to be laminated so as to overlap the GMR element 36 along the outer periphery of the bias conductive film 37.

For example, Si is formed on the bias conductive film 37.
An insulating layer 35c of O ₂ is provided, and a magnetic layer such as a CoFeNi magnetic alloy layer and a conductive layer such as a Cu layer are laminated on the insulating layer 35c so as to overlap the bias conductive film 37 along the outer periphery of the hole 34. An artificial lattice multi-layered film consisting of and is prepared using a sputtering device.

In this case, the CoFeNi magnetic alloy layer is 1
nm and the Cu layer have a thickness of 2.2 nm and are alternately 2
A magnetoresistive effect element (GMR element) 38 having an artificial lattice film structure is formed by forming each layer by 0 layer. This GMR element 38
As shown in FIG. 9, a protective film 39 is deposited on the resist with a resist or the like.

The artificial lattice film and the bias conductive film 37 of the GMR elements 36 and 38 are formed into a predetermined pattern by using the photolithography technique. G in FIGS. 8 and 9
The MR elements 36 and 38 and the biasing conductive film 37 are electrically disconnected from each other in a ring shape, and a predetermined operating voltage is supplied to each of the GMR elements 36 and 38. A predetermined bias current is supplied to the conductive film 37 for use.

In the example of FIG. 9, the bias conductive film 3 is used.
When a predetermined bias current is applied to the GMR element 7, an annular magnetic field is generated around the bias conductive film 37 as in the example of FIG. 1, and the GMR element 36 below and above the bias conductive film 37.
And 38 have the same bias magnetic field H in the opposite direction.
b and -Hb are applied.

Therefore, the GMR elements 36 and 38 operate, for example, using the point b in FIG. 14 and the point c symmetrical thereto as the bias points, respectively. Also in this case GMR
The vertical distance between the elements 36 and 38 is 1 μm or less, which is negligible compared to the recording wavelength λ of the magnetic scale 31, for example, 100 μm.

Therefore, when the magnetic field detecting head 32 is moved relative to the magnetic scale 31 through the hole 34 of the magnetic field detecting head 32 as shown in FIG. As shown in FIG. 14, resistance changes 180 degrees out of phase with respect to changes in the external magnetic field are obtained.

Therefore, two (n + 1/4) λ (where n is 0) magnetic field detection heads 32 are provided for the magnetic scale 31.
(A positive integer including), the two-phase detection voltage signals having a 90-degree phase difference can be obtained in the same manner as in the examples of FIGS. 2 and 3 when the magnetic scale 31 and the magnetic field detection head are separated. The relative displacement amount with 32 can be measured. Therefore, it can be easily understood that the effects similar to those of the examples of FIGS. 2 and 3 can be obtained also in the examples of FIGS. 8 and 9.

Further, in the examples of FIGS. 8 and 9, the magnetically recorded scale surface of the magnetic scale 31 and the surfaces of the GMR elements 36 and 38 are orthogonal to each other, and the scale surface corresponds to the hole 34 of the magnetic field detecting head 32. It adopts a structure in which the machined surfaces hold parallel planes with a constant distance from each other and move relative to each other.

Therefore, even if foreign matter such as dust or cutting powder is mixed in, it is unlikely that the interval or relative angle changes and the level of the output signal fluctuates and the accuracy deteriorates. Further, there is structurally no possibility that cutting chips or the like will enter between the scale surface of the magnetic scale 31 and the detection surface of the magnetic detection head 32 to damage the detection surface and cause a failure.

Further, since the sensitivity is higher than that of the magnetic flux response type detection head using the core, it is possible to secure a sufficient detection voltage signal even for a shorter wavelength.

Further, instead of the relationship between the magnetic scale 1 and the magnetic field detection head 2 shown in FIGS. 2 and 13, FIGS.
1 and as shown in FIG. This FIG. 10, FIG.
The magnetic scale 1 shown in FIG. 1 and FIG. 12 uses a thin plate-shaped CuNiFe magnetic alloy or the like as a magnetic recording medium, on which a constant wavelength λ is recorded in the longitudinal direction by an ordinary magnetic recording head.

In the examples of FIGS. 10, 11 and 12, the detection surface of the magnetic field detection head 2 using the GMR elements R ₁ , R ₂ , R ₃ and R ₄ as shown in FIG. Is held substantially at right angles to the scale surface as shown in FIGS. And as shown in FIG. 12, this GMR
Magnetic field detection head 2 using elements R ₁ , R ₂ , R ₃ and R ₄
Is held in the head case 23, and the magnetic scale 1 and the magnetic field detecting head 2 are separately attached at a constant interval so that they can be relatively displaced in the longitudinal direction of the magnetic scale 1.

When configured as shown in FIGS. 10, 11 and 12, the distance (clearance) between the magnetic scale 1 and the magnetic field detection head 2 is the same as that of a conventional magnetic field detection head using an MR element. Since the recording wavelength λ can be reduced to about 1/4 when opened by the same amount as the above, it is possible to realize a position detecting device with higher accuracy and higher resolution than the conventional case.

In the above-mentioned embodiment, an example in which a GMR element is used as the magnetoresistive effect element has been described, but Fe-Ni (permalloy), N is used as the magnetoresistive effect element.
It goes without saying that an MR element such as i-Co may be used.

Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0073]

According to the present invention, the first magnetoresistive effect element, the biasing conductive film and the second magnetoresistive effect element are laminated in order, so that a bias current is passed through the biasing conductive film. It is possible to apply bias magnetic fields Hb and −Hb of the same magnitude and in opposite directions to the first and second magnetoresistive effect elements. Exactly the phase difference of the value change is 180
Since the first and second magnetoresistive effect elements are laminated, the temperature rise is the same and the magnetic fields received from the magnetic recording medium are the same, so that the drift and amplitude fluctuation of the detection voltage can be improved, There is a benefit of being able to measure the amount of displacement or moving speed with high precision and resolution.

According to the present invention, the magnetoresistive effect element (GMR element) having an artificial lattice film structure in which conductor layers and magnetic layers are alternately laminated is used as the first and second magnetoresistive effect elements. This GMR element has a curve d in FIG.
As shown in Fig. 6, the characteristic of the magnetoresistance change rate with respect to an externally applied magnetic field is larger than that of a conventional MR element such as Permalloy and has a high sensitivity, and when this GMR element is used, the magnetic recording medium and the magnetic field detection are detected. A high-precision, high-resolution position detection device that can increase the clearance (space) with the head and thicken the protective film layer or protect the surface of the GMR element with a thin plate metal material and prevent damage to the detection surface There are benefits that can be obtained.

Further, when the GMR element is used with a clearance equivalent to that of the conventional MR element, the recording wavelength can be further shortened, so that a position detecting device with higher accuracy and higher resolution can be obtained. .

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a magnetic field detection head of the present invention.

FIG. 2 is a diagram schematically showing an embodiment of the position detecting device of the present invention.

FIG. 3 is a diagram used to explain FIG.

FIG. 4 is a diagram provided for explaining FIGS. 2 and 15;

FIG. 5 is a diagram showing an externally applied magnetic field-magnetoresistance change rate of the GMR element.

FIG. 6 is a perspective view showing an example of a rotary encoder.

FIG. 7 is a diagram schematically showing another embodiment of the present invention.

FIG. 8 is a perspective view showing another embodiment of the present invention.

FIG. 9 is a cross-sectional view showing another embodiment of the magnetic field detection head of the present invention.

FIG. 10 is a perspective view showing an example of a position detecting device according to the present invention.

FIG. 11 is a diagram schematically showing another embodiment of the present invention.

FIG. 12 is a perspective view showing an example of a position detecting device according to the present invention.

FIG. 13 is a perspective view showing an example of a position detection device.

FIG. 14 is a diagram for explaining the present invention.

FIG. 15 is a diagram schematically showing an example of a conventional position detecting device.

16 is a diagram used to explain FIG. 15. FIG.

[Explanation of symbols]

 1, 31 Magnetic Scale 2, 32 Magnetic Field Detection Head 10, 33 Substrate 11a, 11b, 11c Insulating Layer 12, 14, 36, 38 GMR Element 13, 37 Biasing Conductive Film 15, 39 Protective Film

Claims (3)

[Claims] 1. A first magnetoresistive effect element, a bias conductive film, and a second magnetoresistive effect element are sequentially laminated on an insulating substrate with an insulating layer interposed therebetween, and the bias conductive film is formed on the bias conductive film. A magnetic field detection head, wherein a predetermined bias current is caused to flow, and bias magnetic fields in mutually opposite directions are applied to the first and second magnetoresistive effect elements. 2. The magnetic field detecting head according to claim 1, wherein the first and second magnetoresistive effect elements have an artificial lattice film structure in which conductor layers and magnetic layers are alternately laminated. A magnetic field detection head characterized by being used. 3. A magnetic recording medium on which magnetic information is recorded,
A magnetic field detection unit that is capable of relative displacement with respect to the magnetic recording medium and that detects the magnetic information; and based on the detected magnetic information, a relative displacement amount or relative amount between the magnetic recording medium and the magnetic field detection unit. A position detecting device capable of measuring a moving speed, wherein the magnetic field detecting section is provided.
Alternatively, a position detecting device using the magnetic field detecting head according to claim 2.