Dynamic magnetic information storage or retrieval – Head – Coil
Patent
1996-01-05
1998-08-18
Wolff, John H.
Dynamic magnetic information storage or retrieval
Head
Coil
G11B 517
Patent
active
057965641
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a magnetic head suitable for video tape recorders or magnetic disc units, etc., and more particularly to a magnetic head in which coil is formed by the thin film process and a method of manufacturing such a magnetic head.
BACKGROUND ART
As a magnetic head used in a magnetic recording/reproducing apparatus such as Video Tape Recorder (VTR) or magnetic disc unit, etc., the so-called metal-in gap type magnetic head in which a metallic magnetic film is formed on the surface where the magnetic gap is formed of a magnetic core consisting of ferrite, the so-called laminate type magnetic head where a metallic magnetic film is caused to be put between bases (substrates) consisting of a pair of non-magnetic materials, and the like are used. Such magnetic heads are required to exhibit more satisfactory electromagnetic conversion characteristic particularly in the higher frequency band in order to cope with realization of high picture quality and/or implementation in a digital form.
However, the above-mentioned metal-in gap type magnetic head has large impedance and is not suitable for use at higher frequency.
Moreover, in the case of the laminate type magnetic head, when the track width is reduced for implementation of high density recording, it is necessary to reduce film thickness of the metallic magnetic film constituting a magnetic path, resulting in lowered reproduction efficiency. Further, since the magnetic path is formed only by the metallic magnetic film, there is the problem in control of magnetic anisotropy of the metallic magnetic film. As a result, it is difficult to obtain high reproduction efficiency. The reason thereof is as follows. While it is generally ideal for the magnetic anisotropy of the magnetic head that the axis of easy magnetization is always perpendicular to the direction of magnetic flux, it is difficult to allow the axis of easy magnetization of the metallic magnetic film to be always in a direction perpendicular to the direction of magnetic flux. In the present state, there only exist isotropic (non-orientation) films having no anisotropy, and films having uni-axial anisotropy in one direction even if there is any anisotropy.
In view of the above, as a magnetic head to cope with high frequency, there have been proposed, for example, as described in the Japanese Patent Application Laid Open No. 231713/1988 Publication and/or the Japanese Patent Application Laid Open No. 248305/1988 Publication, magnetic heads in which the magnetic path constituted with the metallic magnetic film is caused to be smaller than that of the ordinary magnetic head, and a thin film coil is formed on the surface where the magnetic gap is formed by using the thin film process.
However, since such a magnetic head as described in the Japanese Patent Application Laid Open No. 231713/1988 Publication has the process step of forming a metallic magnetic film on a base (substrate) thereafter to fill glass, etc. of low melting point onto the metallic magnetic film to flatten it, there is limitation in magnetic films which can be used. Namely, magnetic films consisting of material to which heat treatment cannot be implemented such as amorphous magnetic material, etc. cannot be used. Moreover, in the case of magnetic films consisting of material which is easy to react with glass such as nitrogen (nitride) system magnetic material, etc., foaming, etc. is produced by reaction with glass, resulting in insufficient filling of glass. Therefore, such magnetic films are not suitable. In the case where any magnetic film easy to react with glass is positively used, processing for suppressing reaction is required, disadvantageously resulting in increased number of process steps. Further, in the case of magnetic heads of such type, since filled glass, etc. is exposed onto the medium slide surface, there is also the problem that the abrasion resistive property is deteriorated.
On the other hand, in the case of magnetic heads as described in the Japanese Patent Application Laid Open No. 24
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Ohmori Hiroyuki
Shouji Mitsuharu
Sugiyama Yasunari
Yamamoto Tetsuya
Sony Corporation
Wolff John H.
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