Hitachi, Ltd.

Hajime Fukke

Katsuyoshi Chiba

Heigo Ishihara

Yoshiki Kato

Yasutaro Uesaka

Iwao Matsuyama

Waichi Nagashiro

Naoki Kodama

Munehisa Mitsuya

Masayuki Katsumoto

Teruo Tsunoda

Motoo Akagi

Teruaki Kobayashi

Hitoshi Inoue

Harukazu Miyamoto

Norio Ohta

Tsuneo Terasawa

Keiji Kataoka

Seiji Yonezawa

Masaru Ito

Tsuneo Suganuma

Yoichi Oba

Keizo Kato

Mitsushi Endo

Yoshiharu Terada

Klaus Kinstatter

The present invention uses a magnetic recording medium equipped with those magnetically readable recording servo pits which are preformed on a magnetic recording medium and have different magnetic characteristics from those of a recording magnetic film, detects magnetically a tracking signal or preformat signals such as sync signals, address signals, and the like, from the magnetic flux distribution (leakage magnetic field) occurring at edges of each of the servo pits using a magnetic head, makes servo control of the position of the magnetic head by the detected tracking signal and records or reads magnetically the data along the center of a track. In the magnetic recording medium of the present invention, magnetically readable, wobbled servo pits or sync pits, track address pits and data pits are preformed on the magnetic recording medium, these pit portions have locally different magnetic characteristics from those of the recording magnetic film and have a magnetic film structure wherein saturated magnetization is smaller than at other portions or the magnetic film is removed locally. These preformed pits can be read magnetically by detecting the local magnetic field (leakage magnetic field) generated at their edges by the magnetic head.

Method of magnetically recording and reading data, magnetic recording

A method for manufacturing a magnetic paint by mixing a resin composition powder as a dispersing binder for a magnetic powder with the magnetic powder, or together with a filler, and grinding the mixture under a high shear stress is disclosed. A magnetic recording medium such as a magnetic disk, etc., prepared by using the magnetic paint, can have a magnetic coating film having a substantially uniform film thickness of not more than 0.9 .mu.m and a surface roughness of not more than 0.05 .mu.m Ra before surface finishing.

Hard disk magnetic recording medium comprising magnetic powder and a

A coating type, magnetic disk is produced by applying a magnetic paint containing magnetic powders in a dispersed state to a non-magnetic substrate, thereby forming a magnetic recording film thereon, and applying surface waves to the magnetic recording film in an undried state. By applying the surface waves to the magnetic recording film, dispersibility and orientation of the magnetic powders are improved and a longitudinally oriented, coating type magnetic disk with distinguished electromagnetic properties, such as a high S/N ratio, etc. can be obtained.

Process for producing a rigid magnetic disk by longitudinally generating

A method for magnetic orientation of a magnetic recording medium using Meissner effect of a superconductor and a system therefor and a magnetic recording medium produced thereby. The magnetic particles of plate hexagonal barium ferrite in the magnetic coating are allowed to orient in the longitudinal direction thereof so that a magnetic recording medium having a magnetic orientation in such direction with the magnetic particles can be obtained.

Method for magnetic orientation of magnetic recording medium using

The present invention proposes a ratio of an applied field H.sub.s to a coercivity H.sub.c as a parameter which gives an influence to the write/read characteristics of a magnetic coated recording medium, especially, a reproduction output E.sub.o at a low recording density and a recording density D.sub.50 which provides an output of the half of E.sub.o. By selecting the ratio H.sub.s /H.sub.c to be not larger than 2.1, a magnetic coated recording medium having large values of E.sub.o and D.sub.50 or suited to a high density magnetic recording can be provided with good reproducibility.

Magnetic coated recording medium and method of manfacturing the same

A coating magnetic recording medium which comprises two or more kinds of magnetic films different from one another provided on the same side surface of a non-magnetic substrate.

Magnetic recording medium

A sufficient reproduced output can be attained even in a coating thickness of as small as 1 .mu.m, preferably 0.1 to 0.5 .mu.m with a magnetic recording medium comprising a substrate and a coating film containing magnetic powder formed on the substrate, wherein the content of the magnetic powder in the coating film is 66 to 90% by weight.

A composition of magnetic recording media consisting of a ferromagnetic powder such as .gamma.-Fe.sub.2 O.sub.3, a binder and single crystal alumina as a reinforcing agent. Single crystal .alpha.-alumina is preferably used as said single crystal alumina and its amount is preferably from 1 to 20% by weight based on the magnetic powder.

Composition of magnetic recording media

A method of manufacturing a paint composite for magnetic films wherein a mixture consisting of a magnetic powder, a polymer such as polyvinylbutyral, and a solvent is ground under a shear stress of 10-400 kg/cm.sup.2, and the ground mixture has a solvent, an epoxy resin and a phenol resin added thereto and is further ground. When a magnetic disk is produced using a paint which has been obtained by executing the first grinding under a shear stress of 10-400 kg/cm.sup.2 with a kneader or the like, it is endowed with excellent electric characteristics and surface flatness.

Method of manufacturing a paint composite for magnetic films

A process for the preparation of a magnetic recording medium comprising;

Growing community of inventors

Tama, Japan

Hajime Fukke