JPH0830926A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PURPOSE:To obtain an MR head usable as a rotary type head by providing an electric circuit including the MR element with a transformer and supplying the AC current from an AC power source via this transformer to the MR element. CONSTITUTION:The electric circuit including the MR element 6 of this MR head is provided with the transformer 11. This transformer 11 is composed of primary side windings 12, secondary side windings 13 and a core 14. Both of the windings 12 and 13 are wound respectively a prescribed number of times on the core 14. The AC power source 15 is connected to the windings 12 and on the other hand, the winding start part 13a of the windings 13 is connected to an upper layer shielding magnetic material 3 and the winding end part 13b thereof is connected to one end 7a of a bias conductor 7. The AC current from the power source 15 flows from the windings 12 to the windings 13 when the electric circuit of the element 6 is provided with the transformer 11 in such a manner. The AC current flows to the conductor 7 connected to the windings 13 and the bias magnetic field generated on the element 6 is impressed on the element 6. Further, the AC current flows to the magnetic material 3 and functions as a sense current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel magnetoresistive effect magnetic head using the magnetoresistive effect magnetic head as a rotary reproducing head.

[0002]

2. Description of the Related Art In recent years, a magnetoresistive effect type magnetic head (hereinafter referred to as MR head) using a magnetoresistive effect element (hereinafter referred to as MR element) such as permalloy having a magnetoresistive effect has been actively developed. Has been.

In such an MR head, the resistance of the MR element made of permalloy changes due to the signal magnetic flux leaking from the magnetic recording medium, and the information recorded on the magnetic recording medium can be read by detecting the change in the resistance. Is configured.

Such an MR head is superior in short wavelength sensitivity to a general electromagnetic induction type magnetic head (hereinafter referred to as an inductive head), and therefore, in narrow track reproduction, short wavelength reproduction, and ultra-low speed reproduction. It is said that high sensitivity can be obtained.

The MR head has, for example, an MR element made of permalloy sandwiched by a pair of shield magnetic bodies, and a bias conductor for applying a bias magnetic field to the MR element is provided on the MR element. Is common.

[0006]

However, in this MR head, the sense current supplied to the MR element for extracting the output was only the direct current. Therefore, until now, the MR head had to be used as a fixed head.
Therefore, like the induction type magnetic head mounted in the recording / reproducing apparatus such as a video tape recorder, it cannot be used as a rotary head. In the inductive magnetic head, the reproduction output decreases when the track is narrowed, but in the MR head, the output does not decrease, which is advantageous when used as a rotary head.

Therefore, the present invention has been proposed in view of the above-mentioned conventional technical problems, and an object thereof is to provide an MR head that can be used as a rotary head.

[0008]

In the MR head according to the present invention, a transformer is provided in an electric circuit including an MR element, and an AC current from an AC power source is supplied to the MR element via the transformer, whereby the above-mentioned problems are solved. To solve.

The MR head according to the present invention faces the MR element arranged so that its longitudinal direction is perpendicular to the surface facing the magnetic recording medium and the surface facing the magnetic recording medium. The tip electrode laminated on the tip side of the element, and the above M
A rear end electrode laminated on the rear end side of the R element, a pair of shield magnetic bodies sandwiching the MR element laminated with the front end electrode and the rear end electrode from the film thickness direction, and a bias magnetic field is applied to the MR element. By including a bias conductor and a transformer provided in an electric circuit including the MR element,
The above problems are solved. In such a case, an AC power supply is connected to the transformer, and an AC current is supplied to the MR element via this transformer.

[0010]

In the MR head of the present invention, since the transformer is provided in the electric circuit including the MR element, if the AC current from the AC power supply is supplied to the MR element through the transformer,
This alternating current functions as a sense current, and the reproduction output signal can be taken out. Therefore, if this MR head is mounted on the rotary drum of a recording / reproducing apparatus such as a video tape recorder, it can be used as a rotary head.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings.

Example 1 The MR head of this example is an example in which the number of electrode terminals is two.

As shown in FIGS. 1 and 2, the MR head of this embodiment has a pair of shield magnetic bodies 2, 3 formed on one side surface of a slider 1 made of Al ₂ O ₃ --TiC or the like.
And an MR element 6 in which a front end electrode 4 and a rear end electrode 5 are laminated between these shield magnetic bodies 2 and 3, and this MR element 6
And a bias conductor 7 for applying a bias magnetic field.

Hereinafter, the shield magnetic body 2 formed in the lower layer will be referred to as the lower shield magnetic body 2, and the shield magnetic body 3 formed in the upper layer will be referred to as the upper shield magnetic body 3.

The MR element 6 is formed, for example, in a substantially rectangular pattern in plan view, and is provided such that its longitudinal direction is perpendicular to a sliding surface (hereinafter referred to as ABS surface 8) with the magnetic recording medium. At the same time, one side edge of the tip side thereof faces the ABS surface 8. The MR element 6 is made of, for example, a ferromagnetic thin film such as permalloy, and is formed on the lower shield magnetic body 2 by a vacuum thin film forming means such as vapor deposition or sputtering via an insulating film 9 functioning as a lower gap film. ing.

The MR element 6 may be a single layer film of a thin film element made of permalloy, but a pair of thin film elements magnetostatically coupled via a non-magnetic insulating layer made of, for example, SiO ₂ is used. It may have a laminated film structure in which the layers are laminated. With the laminated film structure, it is possible to avoid the occurrence of Barkhausen noise.

The tip electrode 4 is directly laminated on the tip of the MR element 6 so that one side edge thereof faces the ABS 8 and is electrically connected to the MR element 6.
The tip electrode 4 has a function as an electrode for supplying a sense current to the MR element 6, and also as an upper gap film of the reproducing magnetic gap.

On the other hand, the rear end electrode 5 is laminated so as to overlap a part of the rear end portion of the MR element 6, and is drawn out to the rear side of the element on the side opposite to the ABS surface 8. The drawn conductor portion of the rear end electrode 5 is connected in series with the bias conductor 7.

The bias conductor 7 is for applying a bias magnetic field to the MR element 6, and includes the front electrode 4 and the rear electrode 5.
And is provided in a direction orthogonal to the longitudinal direction of the MR element 6. The bias conductor 7 is adapted to apply a bias magnetic field along the longitudinal direction of the MR element 6.

The pair of shield magnetic bodies 2 and 3 provided so as to sandwich the MR element 6 from above and below,
It functions as a shield that is not affected by the magnetic field from the medium located away from the MR element 6, and is formed of, for example, permalloy or sendust.

The lower shield magnetic body 2 has the ABS surface 8
Is provided so as to face one side edge thereof in the direction perpendicular to the ABS surface 8. On the other hand, the upper shield magnetic body 3 provided so as to be opposed to the upper shield magnetic body 3 is perpendicular to the ABS surface 8 with one side edge thereof facing the ABS surface 8 like the lower shield magnetic body 2. It is provided to extend to the back side. The upper shield magnetic body 3 is directly laminated on the ABS 8 side with respect to the tip electrode 4, and an insulating layer 10 for ensuring insulation with the MR element 6 and the bias conductor 7 is provided on the rear side thereof. Are stacked.

In particular, in this MR head, the transformer 11 is provided in the electric circuit including the MR element 6.
As shown in FIG. 1, the transformer 11 is composed of a primary winding 12, a secondary winding 13 and a transformer core 14 which are formed by a vacuum thin film forming technique.

The winding 12 on the primary side and the winding 13 on the secondary side are
Each of them is wound around the transformer core 14 by a predetermined number. An AC power supply 15 is connected to the winding 12 on the primary side. The input signal from the AC power supply 15 may be a sine wave, a triangular wave, or a rectangular wave.

On the other hand, in the secondary winding 13, the winding start portion 13a is connected to the upper shield magnetic body 3 and the winding end portion 13b is connected to one end side 7a of the bias conductor 7.

The electrical circuit of the MR head, as shown in FIG. 3, the resistance R _{Bi the as} the resistance R _MR MR element 6 of the bias conductor 7 are connected in series, the electrode terminals T _1, T ₂ of the element It is configured as two.

When the transformer 11 is provided in the electric circuit of the MR element 6 as described above, the AC current I _MR from the AC power supply 15 is generated.
Flows from the winding 12 on the primary side to the winding 13 on the secondary side.
The bias conductor 7 connected to the secondary winding 13
The alternating current I _MR flows to the MR element 6, and the bias magnetic field generated by the alternating current I _{MR on the} MR element 6 is applied to the MR element 6. Further, this alternating current I _MR flows to the rear end electrode 5, passes through the MR element 6, and passes through the front end electrode 4 to the upper shield magnetic body 3. The alternating current I _MR flowing through the MR element 6 functions as a sense current.

Therefore, when the MR head is mounted on the rotary drum of a recording / reproducing apparatus such as a video tape recorder, the AC sense current causes the reproduction recorded on the magnetic recording medium running around the peripheral surface of the rotary drum. The signal can be read. That is, as a magnetic head for a helical scan recording system,
Such an MR head can be used.

Example 2 The MR head of this example is an example in which the number of electrode terminals is three.

In this MR head having a three-terminal structure, as shown in FIG. 4, the conductor pattern 7b is drawn out from the bent portion of the bias conductor 7 formed around the rear end side of the MR element 6. There is. The process will be described below with reference to the electrical schematic, the MR head is connected in parallel with resistor R _MR of the resistor R _Bias and the MR element 6 of the bias conductor 7 as shown in FIG. 5, the electrode terminals of the element T _1, T ₂ and T ₃ are three.

Also in the MR head of this embodiment, like the MR head of the first embodiment, since the transformer 11 is provided in the electric circuit of the MR element 6, it can be used as a magnetic head for a helical scan recording system. .

Example 3 The MR head of this example is an example in which the number of electrode terminals is four.

In this MR head having a four-terminal structure, as shown in FIG. 6, the bias conductor 7 and the conductor for passing the sense current are made independent. That is, the MR head is made independent of the resistance R _MR of the resistor R _Bias and the MR element 6 of the bias conductor 7 as shown in the electrical circuit of FIG. 7,
The device has four electrode terminals T ₁ , T ₂ , T ₃ , and T ₄ .

Also in the MR head of this embodiment, like the MR head of the first embodiment, since the transformer 11 is provided in the electric circuit of the MR element 6, it can be used as a magnetic head for a helical scan recording system. .

[0034]

As is clear from the above description, in the MR head of the present invention, since the transformer is provided in the electric circuit including the MR element, the AC current from the AC power source is passed through the transformer to the MR element. By supplying this to the AC current, the AC current functions as a sense current, and the reproduction output signal can be taken out. Therefore, if this MR head is mounted on the rotary drum of a recording / reproducing apparatus such as a video tape recorder, it can be used as a rotary head.

[Brief description of drawings]

FIG. 1 is a schematic plan view of an MR head of Example 1. FIG.

FIG. 2 is a cross-sectional view of the MR head of Example 1.

3 is an electric circuit diagram of the MR head of Example 1. FIG.

FIG. 4 is a schematic plan view of an MR head of Example 2.

5 is an electric circuit diagram of the MR head of Example 2. FIG.

FIG. 6 is a schematic plan view of an MR head of Example 3.

7 is an electric circuit diagram of the MR head of Example 3. FIG.

[Explanation of symbols]

 1 slider 2 lower shield magnetic material 3 upper shield magnetic material 4 front electrode 5 rear electrode 6 MR element 7 bias conductor 8 ABS surface 11 transformer 12 primary winding 13 secondary winding 14 transformer core 15 AC Power supply

Claims (3)

[Claims] 1. A magnetoresistive effect magnetic head, wherein a transformer is provided in an electric circuit including the magnetoresistive effect element, and an AC current from an AC power supply is supplied to the magnetoresistive effect element via the transformer. 2. A magnetoresistive effect element arranged so that its longitudinal direction is perpendicular to a surface facing the magnetic recording medium, and a tip side of the magnetoresistive effect element facing the facing surface facing the magnetic recording medium. And a pair of shields sandwiching the magnetoresistive effect element in which the magnetoresistive effect element in which the front end electrode and the rear end electrode are laminated is sandwiched from the film thickness direction. A magnetoresistive effect magnetic head comprising a magnetic body, a bias conductor for applying a bias magnetic field to the magnetoresistive effect element, and a transformer provided in an electric circuit including the magnetoresistive effect element. 3. The magnetoresistive effect magnetic head according to claim 2, wherein an AC power supply is connected to the transformer, and an AC current is supplied to the magnetoresistive effect element via the transformer.