Dynamic magnetic information storage or retrieval – Head – Erase
Patent
1984-12-04
1988-09-27
Hecker, Stuart N.
Dynamic magnetic information storage or retrieval
Head
Erase
360110, 360126, 360122, G11B 516, G11B 522
Patent
active
047746165
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a magnetic head, for forming guard bands on a magnetic recording medium, and a process of fabrication thereof and, more particularly, to a magnetic head suitable for use in a recording and reproduction device for magnetic discs.
In a magnetic disc device for forming recording tracks in the circumferential direction around a disc-shaped recording medium, crosstalk between adjacent tracks becomes a problem during reproduction if the spacing of the tracks is reduced to increase the recording density.
For this purpose, the recording and reproduction magnetic head used in the prior art has a structure such as that shown in FIGS. 1 and 2. This magnetic head is constructed of three head cores 10, 11 and 12. The first head core 10 is formed so that it has a functional gap 14 and a coil-winding aperture 15, and is constructed of a magnetic core portion 13 made of ferrite and an L-shaped member 16 made of a non-magnetic material such as ceramic. Similarly, the second and third head cores 11 and 12 are constructed of magnetic core portions 17 and 18 of ferrite and L-shaped non-magnetic members 23 and 24, respectively, and are formed so as to have functional gaps 19 and 20 and coil-winding apertures 21 and 22, respectively. The head cores 10, 11 and 12 are cut to predetermined widths out of the same block and are joined together to form a monolithic structure, as shown in FIG. 2. The central head core 10 is used for recording and reproduction, whereas the head cores 11 and 12 at either side thereof are used for erasure.
Because of this construction, the pair of erasure gaps 19 and 20 scan only the side portions of the recording track formed by the recording and reproduction gap 14 on the surface of the recording medium adjacent to the magnetic head of FIG. 2. As a result, the two sides of the recording track act as guard bands which are substantially completely signalless, so that little crosstalk is generated from adjacent tracks during the reproduction, even if the track spacing is narrowed.
In the magnetic head of this construction, however, the head cores 10, 11 and 12 have to be connected together after being cut from the block. During this process, the alignment of each of the gaps 14, 19 and 20 in particular is an extremely difficult job. If the track width is 30 .mu.m or less, moreover, the mechanical strength of the head cores is reduced so that they are difficult to machine.
Recently in order to reduce the recording wavelengths used, a recording medium utilizing high coercive forces has been employed. As a result, conventional magnetic heads made of a ferrite material are not capable of adequately recording on such a recording medium. Magnetic materials with high saturation magnetic flux densities and high permeabilities are limited to metallic magnetic materials. As known in the art, however, the metallic magnetic materials in bulk have the disadvantage that they cannot provide satisfactory characteristics in the high-frequency range because of eddy-current losses. In order to avoid this disadvantage, a magnetic head has been proposed which employs multi-layered metallic magnetic films prepared by thin-film formation techniques. It is, however, extremely difficult to realize the magnetic head of the structure of FIGS. 1 and 2 by this method.
Japanese Patent Laid-Open No. 57-44219 a magnetic head in which a head element portion, having a recording and reproduction gap, and a head element portion, having a pair of erasure gaps are joined together such that they are arranged to have their individual gaps in parallel with each other and such that they are perpendicular to the gap direction. However, the magnetic head thus disclosed does not use a thin film of metallic magnetic materials so that it cannot obtain the advantage which could be obtained by making the magnetic materials thin.
The present invention is designed to solve these various problems, and provides both a magnetic head which has a recording and reproduction gap and a pair
REFERENCES:
patent: 4423550 (1984-01-01), Fujioka et al.
patent: 4425701 (1984-01-01), Takahasi et al.
patent: 4559572 (1985-12-01), Kumasaka et al.
patent: 4608293 (1986-08-01), Wada et al.
patent: 4642719 (1987-02-01), Morita et al.
Fujiwara Hideo
Kudo Mitsuhiro
Kumasaka Noriyuki
Otomo Shigekazu
Saito Noritoshi
Garcia Alfonso
Hecker Stuart N.
Hitachi , Ltd.
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