Hitachi, Ltd.

Tatsuo Kawaide

Takaaki Shirakura

Noriyoshi Goda

Shinya Matsuoka

Isao Sakaguchi

The present invention relates to a high-density magnetic recording medium (or 'media' as it is sometimes called) for a recording/reproduction system (such as thosed used in computer disk drives) and, more particularly, to a magnetic recording medium having a plurality of magnetic recording layers such that the uppermost layer is comparatively thinner and more densely structured than the lower magnetic recording layers. The present magnetic recording medium comprises a non-magnetic plated substrate, a non-magnetic underlying layer laminated on the plated substrate, a plurality of magnetic alloy layers including the uppermost layer laminated onto the underlying layer, a non-magnetic covering layer laminated onto the uppermost layer, and a lubricating layer formed onto the non-magnetic covering layer. The present invention improves the corrosion resistance of an alloy-type magnetic recording medium while maintaining or exceeding the recording/reproducing characteristics of such media, all at a desirable cost of production.

Magnetic recording medium and method of producing same

A method of orienting magnetic particles in the thin magnetic film of a magnetic disc in the circumferential direction of the magnetic disc is disclosed in which, in order to improve the magnetic squareness of the thin magnetic film and to eliminate the nonuniformity thereof, a magnetic field formed between a pair of magnetic poles which have the same polarity and disposed so as to be symmetrical with respect to the magnetic disc, is first applied to both surfaces of the magnetic disc immediately after the thin magnetic film has been formed on the magnetic disc, and then magnetic fields from magnetic poles of different polarity are alternately applied to the magnetic disc. In a modified version of this method, particle orientation is performed in the following manner. That is, in a period when the magnetic film is not yet dried, a magnetic field formed between magnetic poles which have the same polarity and are symmetrical with respect to the magnetic disc, is first applied to the magnetic disc, and then magnetic fields from magnetic poles of different polarity are alternately applied to the magnetic disc. Further, after the thin magnetic film has been dried, a magnetic field formed between magnetic poles which have the same polarity and are symmetrical with respect to the magnetic disc, is again applied to the magnetic disc.

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Odawara, Japan

Tatsuo Kawaide