JPS62141620A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To permit easy processing of the output signal of YMR head by providing another shielding yoke which is so constituted as to extend from a front upper yoke and to cover the upper yokes to said head. CONSTITUTION:The upper yokes 2, 3 are usually manufactured of a 'Permalloy(R)' film, etc. having about 0.5-1.0mum film thickness and act as the magnetic path to conduct the signal magnetic field generated in a magnetic recording medium 9 to an MR element 4. The MR element 4 consists of 'Permalloy(R)' of 300-500Angstrom film thickness and the length thereof is set at about 50mum track width. This head has another shielding yoke 7 which is so constituted as to extend from the front upper yoke 2 and to cover the entire part of the upper yokes 2, 3. This shielding yoke 7 is constituted of the material similar to the material of the upper yokes 2, 3 and is formed by maintaining a specified spacing from the upper yokes 2, 3. The direct jumping of the magnetic flux generated from the long wavelength signal on the magnetic recording medium into the MR element is obviated by such shielding yoke 7 even if there is an aperture 11 between the upper yokes 2 and 3.

Description

Detailed Description of the Invention (Technical Field) The present invention detects signals recorded on a magnetic recording medium using a magnetoresistive element (hereinafter referred to as Ml? element) that applies the magnetoresistive effect of a ferromagnetic thin film. This invention relates to thin film magnetic heads.

(Prior Art) It is known that a thin film magnetic head that utilizes the magnetoresistive effect of a ferromagnetic thin film has many advantages over the commonly used wire-wound magnetic head. In other words, a thin film magnetic head receives a signal magnetic field generated from a magnetization pattern recorded on a magnetic recording medium and extracts this as a voltage change based on a resistance change of an MR element, so it does not depend on the transfer speed of the magnetic recording medium. It is possible to reproduce a signal without any noise, and when the transfer speed is low, a reproduced signal with higher output can be obtained than with a wire-wound magnetic head. In actual use, rather than constructing a thin-film magnetic head with a single MR element, the MR element part is separated from the head tip, and a magnetic flux introduction path (yoke) is arranged to guide the magnetic flux generated in the magnetic recording medium to the MR element part. 2 Normal yoke type Ml head (hereinafter referred to as Y
A thin-film magnetic head (referred to as an MR head) is more effective in improving signal resolution and durability of the MR element, and in recent years this type of head has been attracting attention as a fixed head digital audio playback head. (Summary of the 8th Japanese Society of Applied Magnetics Academic Lectures (1984) I4■)
+3-11r yoke type MR throat regeneration characteristics").

As shown in Figure 2, this conventional thin film magnetic head consists of a lower yoke (6), an insulator (8) in which a magnetoresistive (MR) element (4) and a conductor (5) are embedded, and a magnetoresistive effect(
The MR) element (4) is composed of an opening (11) at the top and upper yokes (2, 3) at the front and rear.

Such a conventional thin film magnetic head equipped with an MR element has an opening (11) above the MR element (4).
For this reason, it is known that magnetic flux generated by long wavelength signals on the magnetic recording medium jumps directly into the MR element. Furthermore, the signal magnetic flux jumps into the Mfl element due to the YMR
This has the disadvantage that processing of the output signal obtained from the head, especially waveform equalization, becomes extremely complicated.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems, and its object is to facilitate output signal processing of a YMR head.

That is, in the present invention, a magnetoresistive element (1) and a conductor (
5) is buried substantially parallel to form an insulating layer (8);
Next, the magnetoresistive element (4) has an opening (11) and the insulating layer (8) is covered with the front and rear upper yokes (2, 3) made of a high magnetic permeability magnetic material for the nodal. A thin film magnetic head comprising: another shield yoke (7) extending from the previous upper yoke (2) and configured to cover the upper yoke (2°3). provide.

The present invention will be explained in detail based on examples.

(Example) FIG. 1 shows an embodiment of a thin film magnetic head according to the present invention,
FIG. 3 is a cross-sectional view in a direction perpendicular to the track width direction.

The upper yokes (2, 3) are usually made of permalloy film or the like with a thickness of about 0.5 to 1.0 μm, and are used for magnetic recording media (
It becomes a magnetic path that guides the signal magnetic field generated in step 9) to the MR element (4). The Mrt element (4) is made of permalloy and is manufactured by a method such as vapor deposition or sputtering, and has a film thickness of 30 mm.
The number of people is 0 to 500, and the length is set to about 50 μm of the track width. In addition, in order to apply a bias magnetic field to the MR element (4), A, 1-Cu, Au, Ag, A12-S
A conductor (5) made of i-alloy or the like is provided.

The head gap (10) is preferably set to about 0.2 to 0.3 μm since the minimum recording wavelength actually used is about 0.5 μm.

The lower yoke (6) is made of a high permeability magnetic material and is generally made of
Polycrystalline NiZn ferrite substrate, single crystal or polycrystalline M
An nZn ferrite substrate is used. The track width is usually 50μ since YMII heads have a multi-track configuration.
Although the width is set to about m, the width is not limited to this, and various widths can be used.

The insulator (8) embedding the MR element (4) and the conductor (5) is made of SiOt, A-03, Si3N4, etc.
Its one end is closed by the upper and lower yokes, but the other end forms a head gap (10) and is not closed. This head gap (10) is formed to pick up leakage magnetic flux from the magnetic recording medium.

In particular, the magnetic head of the present invention includes another shield yoke (7) extending from the previous upper yoke (2) to cover the entire upper yoke (2, 3).

The shield yoke (7) is made of the same material as the upper yokes (2, 3), and is formed at a constant distance from the upper yokes (2, 3).

For this shield yoke (7), the upper yoke (2,
Even with the opening (11) in 3), the magnetic flux generated from the long wavelength signal on the magnetic recording medium does not directly jump into the MR element. This is because the magnetic flux from the long wavelength signal passes through the shielding yoke (7) to the upper yoke, from the rad gap portion (1), through the head gap to the lower yoke (6).

Therefore, in a YMrl head with such a structure,
Conventional type YMR with the structure shown in Figure 2
Compared to the head, the output car frequency loss characteristics are obtained. That is, the output at a certain high frequency fI■ is Vll, "I
When the output at a frequency rL lower than + is VL and the ratio V [-(/V L), YMR according to the present invention
The head can take a larger value than the conventional type YMR head. In Fig. 3, a is the conventional type YMrt.
Output-frequency characteristics of the head, b shows the output-frequency characteristics of the YMR head according to the present invention. This is M
It is shown that the output-frequency characteristics are improved by reducing the intrusion of magnetic flux due to the long wavelength signal to R hydrogen atoms.

On the other hand, in the desired frequency band fmin-fmax when the YMR head is actually used, the reproduction output of the YMR head must be flattened, but the output-frequency difference as shown in Figure 3 Based on the present invention having the characteristics < YMR head and conventional type YMR
FIG. 4 shows the frequency characteristics of the waveform equalizer for the head. "Since min-rmax is the desired frequency band, the reproduction output of the YMR head within this band must be waveform equalized so that it becomes like the dashed line C. After the amplifier output of the conventional type YMR head, The solid line e indicates the characteristic of . In order to flatten this, the frequency characteristic of the waveform equalizer must be as shown by the solid line ``. The characteristic after the head amplifier output is shown by the solid line d. To flatten this, the frequency characteristic of the waveform equalizer should be made to be the solid line g. This can be clearly seen from Figure 4. As a result of the present invention, the waveform equalizer for a YMR head requires less circuit load than the waveform equalizer for a conventional YMR head.

(Effects of the Invention) According to the present invention, the magnetic flux due to the long wavelength signal that enters from the opening of the MRX element is blocked, and the Y
A MIt head is obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a YMR head, not showing an embodiment of the present invention. FIG. 2 is a cross-sectional view of a conventional YIVIR head. FIG. 3 is a diagram showing the Kerr frequency characteristics of a YMR head according to the present invention and a conventional YMR head, and FIG. FIG. 3 is a diagram showing frequency characteristics of a waveform equalizer in the head. The numbers in the diagram are as follows: (1)...Rad gap to upper yoke, (2)...
・Front upper yoke, (3) ... Rear upper yoke, (4
)...MR hydrogen element (5)...Conductor, (6)...
... lower yoke, (7) ... shield yoke,
(8)...Insulator, (9)...Magnetic recording medium, (10)...Head gap, (11) opening. Figure 3 Figure 4

Claims (1)

[Claims] 1. Lower yoke (6
), an insulating layer (8) is formed by embedding a magnetoresistive element (4) and a conductor (5) approximately in parallel, and then an opening (11) is formed on the magnetoresistive element (4). In the thin-film magnetic head, the front and rear upper yokes (2, 3) are made of a high permeability magnetic material for shielding and cover the insulating layer (8). A thin film magnetic head characterized in that it comprises another shield yoke (7) configured to cover the upper yokes (2, 3).