Dynamic magnetic information storage or retrieval – Head – Core
Patent
1985-12-23
1988-08-16
Wolff, John H.
Dynamic magnetic information storage or retrieval
Head
Core
G11B 512
Patent
active
047648333
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
The invention relates to a magnetic head of perpendicular magnetization type, and more particularly, to a perpendicular magnetic head in which a main pole film formed by a magnetically soft film having a high permeability is held sandwiched between at least a first and a second non-magnetic block which are joined together.
BACKGROUND
In a perpendicular magnetic recording system in which a magnetic recording medium is magnetized in the direction of thickness, it is recognized that the shorter the wavelength of a magnetization which is magnetically recorded, the less in principle will be the self-demagnetization within the recording medium, a result that is suitable in achieving a high density recording (refer Nikkei Electronics, Oct. 25, 1982 Issue, pages 142 to 143).
A perpendicular magnetic recording requires a recording medium which exhibits a pronounced magnetic anisotropy in the perpendicular direction, and a magnetic recording head which develops a strong, sharply defined perpendicular component field. Known magnetic recording mediums which exhibit such a pronounced magnetic anisotropy in the perpendicular direction includes Co-Cr, barium ferrite, Co-O and the like. A magnetically soft film of a high magnetic permeability comprising Fe-Ni, permalloy, etc., is formed on a flexible base which may be formed by polyethylene terephthalate (PET) or the like, followed by Co-Cr film which is formed thereon, thus providing a two layer perpendicular magnetic recording medium which is suitable for a high density recording.
For use as a magnetic head which develops a strong, sharply defined perpendicular component field, there is proposed an auxiliary pole excited magnetic head (refer S. Iwasaki and Y. Nakamura; "An Analysis for the Magnetization Mode for High Density Magnetic Recording"; IEEE Trans. on Magn., Vol. MAG-13, No. 5, p 1272-1277, September 1977).
Such an auxiliary pole excited magnetic head 10 is illustrated in FIG. 1. As shown, it comprises a main pole 1, and an auxiliary pole 2 which is disposed in opposing relationship with the main pole 1 and is spaced therefrom by a given air gap 3, the auxiliary pole comprising a block 2a of a high permeability magnetic material such as ferrite and carrying a winding 2b thereon which is utilized to pass or develop an electric current representing information signal. During a recording and reproduction, a magnetic recording medium 4 is placed into the air gap 3 with the magnetized or magnetizable film of the medium 4 placed in sliding contact with the lower end face of the main pole 1. As shown in FIG. 2, the main pole 1 may comprise a film 1a of a magnetically soft material having a high permeability such as Co-Zr-Nb (hereafter referred to as a main pole film) which is held sandwiched between a pair of joined members such as a magnetic member 1b as may be formed from ferrite and a non-magnetic member 1c as may be formed from glass. Alternatively, a main pole 1' shown in FIG. 3 comprises the main pole film 1a which is held sandwiched between a joined member including the magnetic member 1b and the non-magnetic member 1c located on one side and a non-magnetic member 1c' which is constructed of the same material as that used to form the non-magnetic member 1c.
The magnetic recording and reproduction onto or from the magnetic recording medium 4 with the described head 10 takes place as follows: Initially, when effecting a magnetic recording, an electric current representing information signal which is fed from a suitable signal processing circuit, not shown, is applied to the winding 2b shown in FIG. 1, thereby causing the auxiliary pole 2 to develop a magnetic field. Under the influence of this field, a strong, sharply defined perpendicular field is produced through the main pole film 1a of the main pole 1, and such perpendicular field causes a reversal in the magnetization of the magnetizable film of the recording medium 4. During reproduction, the perpendicular field produced by the magnetization in the magnetizable film of the recording med
REFERENCES:
patent: 4315291 (1982-02-01), Lazzari
patent: 4383284 (1983-05-01), Isshiki
patent: 4385334 (1983-05-01), Yanagida
patent: 4571653 (1986-02-01), Suzuki et al.
Imamura Tatsuo
Yamamoto Hiroyuki
Olympus Optical Company Ltd.
Weinstein Louis
Wolff John H.
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