JPS61907A - Magnetoresistance effect type playback head - Google Patents

Abstract

PURPOSE:To eliminate the conductivity fault arising from the generation of scratch flaws owing to foreign matter and to improve reliability by changing the thickness of the magnetic material layer for shielding on at least one side of the magnetic material layers for shielding on both sides in such a manner that the thickness is smaller at the top end facing a recording medium than in the other part. CONSTITUTION:The magnetic material layer 15 for shielding is so formed that the thickness P1 at the top end facing the magnetic tape or recording medium 8 is as small as, for example, <=0.2mum and the thickness in the other part, namely, the part upper than the part corresponding to about 1/2 the height (h) of magnetoresistance effect element 2, 3 is as large as 2mum. The end face of the layer 15 exposed to the sliding contact surface of the head which contacts slidingly with the medium 8 has the small width in the sliding direction of the medium 8 has the small width in the sliding direction of the medium and therefore even if dust, metallic powder, etc. are made captive in the sliding contact surface of the head, the electrical conduction between the layer 15 and the element 2 or 3 arising from the generation of the scratch flows owing to such foreign matter is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Jl) Industrial Field of Application The present invention relates to a magnetoresistive reproducing head used in a magnetic tape device, etc., and particularly relates to a magnetoresistive reproducing head used in a magnetic tape device, etc. , relates to a head structure that eliminates electrical continuity failure between a magnetoresistive element and a shielding magnetic layer.

A magnetic flux-responsive magnetoresistive effect using a magnetoresistive element configured to output the strength of a magnetic field as a change in electrical resistance, as a magnetic head for reproducing recorded edge information on a magnetic tape recording medium in a magnetic tape device, etc. Type reproduction heads are well known, and various types of reproduction heads have already been proposed.

In such a magnetoresistive reproducing head, when electrical conduction occurs between the magnetoresistive element and the shielding magnetic layer on the head sliding surface that comes into contact with the magnetic tape recording medium, the resistance value of the magnetoresistive element increases. Therefore, it is important to reliably insulate the magnetoresistive element and the shielding magnetic layer.

(bl) Prior Art The conventional magnetoresistive read head described above generally has a magnetic substrate 1 made of, for example, Ni-Zn ferrite or Mn-Zn ferrite, as shown in the cross-sectional view of the main part in FIG. , two magnetoresistive elements (hereinafter referred to as MR elements) 2.3 made of Ni-Fe permalloy are provided with a non-magnetic insulating layer 4 made of 5j02 or the like interposed therebetween as shown in the figure, and Ni- A shielding magnetic material Jtl'f5 made of Fe permalloy is adhered thereon, and a cover plate 7 is further attached thereon with a glass adhesive 6 or the like.

The magnetic substrate 1 also serves as a shield layer, and has two layers as described above. By configuring the ll+ element 2.3 to be sandwiched between the magnetic substrate 1 and the shielding magnetic material N5, unnecessary magnetic flux from the recording medium is guided to the shield layer, improving the reproduction resolution of the head. There is.

Therefore, in order to reproduce recorded information on the opposing magnetic tape recording medium 8 using the magnetoresistive reproducing head having such a configuration, each time a constant current is supplied in the same direction to the two MR elements 2.3. As a result, bias magnetic fields in opposite directions are applied to the two MR elements 2 and 3 by the magnetic fields generated by these bias currents.

At this time, the two facing elements 2,
3, a resistance change occurs in the opposite direction.

This change in electrical resistance is converted into voltage to differentially detect the recorded signal and perform playback.

(C1 Problem to be Solved by the Invention) However, in the conventional magnetoresistive reproducing head described above, when performing reproduction by sliding contact with the magnetic tape recording medium 8, the sliding head does not come into contact with the magnetic tape recording medium 8. Foreign matter such as minute dust or metal powder is entangled in the surface, and this foreign matter causes the relatively soft surface (Vickers hardness Hv
-100 to 200) and is highly malleable and ductile.
Scratches are likely to occur on the end face of the shielding magnetic layer 5 made of Fe permalloy.

Furthermore, when this scratch occurs, the foreign matter that creates the scratch scratches the Ni-
Fe permalloy is thinly stretched, and the thinly stretched Ni
The -Fe permalloy foil piece is further stretched by sliding with the magnetic tape recording medium 8, and finally connects with the shielding magnetic layer 5 and Ml? A failure occurs in which electrical continuity occurs between the elements 2 or MR elements 3.

Therefore, due to such an electrical conduction phenomenon, the predetermined current supplied to the MR element 2 or 3 also flows to the shielding magnetic layer 5, etc., which not only deteriorates the bias characteristics but also degrades the reproduction. This greatly distorts the signal waveform. Furthermore, there is a drawback that the resistance value of each MR element 2, 3 decreases, and the reproduced signal output decreases.

In order to eliminate the above-mentioned conventional drawbacks, the present invention aims to solve the problem that the cause of electrical conduction failure between the shielding magnetic layer and the MR element on the sliding contact surface of the head that comes into contact with the magnetic tape recording medium is the shielding magnetic layer. Focusing on the fact that it is closely related to the N thickness of the layer, we thinned the shielding magnetic layer that forms a part of the head sliding contact surface to increase the width of the end surface in the sliding direction of contact with the recording medium. The object of the present invention is to provide a highly reliable magnetoresistive reproducing head which is small in size and eliminates conduction failure caused by scratches caused by foreign matter.

fdl Means for Solving the Problems An object of the present invention described above is to provide a head structure in which a magnetic material layer for shielding is provided on both sides of a magnetoresistive element via a nonmagnetic insulating layer. The layer thickness of the shielding magnetic layer on at least one side of the body layer is changed to be thinner at the tip portion facing the recording medium than the other portion, and the tip portion of the shielding magnetic layer facing the medium is changed. The layer thickness of
, 2 μm or less, this is achieved by the magnetoresistive type reproducing device of the present invention.

(1'!l Effect, that is, in the present invention, the cause of electrical conduction failure between the shielding magnetic layer and the MR element on the head sliding contact surface that comes into contact with the magnetic tape recording medium is the shielding magnetic layer Focusing on the fact that it is closely related to the layer thickness of the layer, the head configuration without a shielding magnetic layer and the thickness of the shielding magnetic layer are set to 0.2 to 3.

As a result of prototyping several types of heads with different sizes of micrometers and conducting long-term sliding tests on each of these prototype heads, we found that:
(1) In a head configuration without a shielding magnetic layer, there is no short-circuit failure of the MR element.

(2) Even in a head having a shielding magnetic layer with a layer thickness of 0.2 μm, the shielding magnetic layer and Ml? There is no occurrence of electrical continuity failure between elements. (3) Layer thickness is 31tt
It has been found that the above-mentioned electrical continuity failure is likely to occur in a head having an n shielding magnetic layer.

From these experimental results, it is preferable to reduce the thickness of the shielding magnetic layer in order to eliminate the electrical continuity problem. (Indeed, the shielding effect deteriorates, causing left-right asymmetric distortion in the output waveform of the MR element, and the reproduction resolution decreases.

Therefore, in the present invention, the thickness of the shielding magnetic layer is made thinner at the tip facing the recording medium and thicker at the other parts, thereby increasing the thickness of the shielding magnetic layer at the head sliding contact surface without reducing the shielding effect. Shielding magnetic layer and MR
It becomes possible to obtain a highly reliable magnetoresistive reproducing head free from electrical #1ffl interference between elements.

(fl Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a main part of an embodiment of a magnetoresistive reproducing head according to the present invention.

In the figure, 1 is a magnetic substrate made of, for example, Ni-Zn ferrite or Mn-Zn ferrite, which also serves as a magnetic material for shielding, and 2.3 is made of Ni-Fe permalloy, which outputs signal waveforms of opposite polarity. These are two MR elements, and as shown in the figure, they are provided with a nonmagnetic insulating layer 4 made of 5i02 or the like interposed therebetween.

On the top surface, for example, amorphous C, which is a feature of the present invention, is applied.
The shielding magnetic layer 15 made of o-Zr has a layer thickness P1=0.2 at the tip facing the magnetic tape recording medium 8. +
The layer thickness of the other part, that is, the part above the part corresponding to approximately 2 of the height h of the MR elements 2 and 3 is P2.
-2 μm thick.

Furthermore, there is a cover plate 7 made of ceramics etc.
is pasted with glass adhesive 6 or the like, and the two M
The R element 2.3 is disposed between the magnetic substrate 1 and the shielding magnetic material IWt15, as in the conventional case, and is configured to function as a shielding magnetic material.

Therefore, in the magnetoresistive head configured as described above, the end face of the boroseal layer 15 for the seal 1 exposed on the head sliding surface that comes into contact with the magnetic tape recording medium 8 in the medium sliding direction. Because the width is small, even if dust, metal powder, etc. are caught in the sliding contact surface of the head that slides on the magnetic tape recording medium, the conventional Magnetic layer 1 for shielding such as
It becomes possible to eliminate the phenomenon that electrical continuity occurs between the MR element 5 and the Ml+ element 2 or the MR element 3.

(g) Effects of the Invention As is clear from the above explanation, the magnetoresistive read head according to the present invention has a head sliding contact surface that slides in contact with the magnetic tape recording medium without reducing the shielding effect. It has the excellent effect of easily eliminating electrical conduction problems between the magnetic layer and the MR element, significantly improving reliability, and can be used in many types of magnetoresistive playback heads. Extremely advantageous.

[Brief explanation of drawings]

FIG. F is a cross-sectional view of a main part showing an embodiment of a magnetoresistive read head according to the present invention, and FIG. 2 is a cross-sectional view of a main part of a conventional magnetoresistive read head. In the drawings, l is a magnetic substrate, 2.3 is a magnetoresistive element, 4 is a non-magnetic insulating layer, 15 is a shielding magnetic layer, 6 is a glass adhesive, 7 is a cover plate,

Claims (2)

[Claims] (1) In a head configuration in which shielding magnetic layers are provided on both sides of the magnetoresistive element through nonmagnetic insulating layers, the shielding magnetic layer on at least one side of the shielding magnetic layers on both sides is A magnetoresistive reproducing head characterized in that the layer thickness is made thinner at the tip facing the recording medium than at other parts. (2) The magnetoresistive reproducing head according to claim (1), wherein the thickness of the tip of the shielding magnetic layer facing the medium is 0.2 μm or less.