Hitachi, Ltd.

Hitachi Computer Peripherals Co., Ltd.

Hiroshi Yashiki

Youichi Inomata

Hideaki Tanaka

Yoshiki Kato

Masaki Ohura

Kenichi Gomi

Yoshihiko Miyake

Yoshihiro Moriguchi

Sigeru Sano

Kenji Morita

Hiroshi Matsumoto

Tokuho Takagaki

Takaaki Shirakura

Fuminori Ishikawa

Noriyuki Shige

Tokuhiro Tsukiyama

Hiroyuki Sugimoto

Shinya Matsuoka

Tatsuya Yoneda

Norikazu Nagase

Shoichi Sawahata

Masanori Arayashiki

Hiroko Saito

Toshinori Hirano

Yoichi Inomata

Kazuhiko Tsutsumi

Osamu Hirose

A magnetic disk includes a substrate, a magnetic layer, and a protective layer. At least one region of a surface of the magnetic disk has protrusions. A height of each of the protrusions is not less than 5 nm and not greater than 40 nm, and is within &plusmn;30% of an average height of the protrusions. A density of the protrusions is not less than 200/mm,and is not greater than 250,000/mm,. A width of a surface of each of the protrusions in a radial direction of the magnetic disk is not less than 0.1 &mgr;m and is not greater than 10 &mgr;m. The protrusions are discrete protrusions aligned in a spiral direction of the magnetic disk at a predetermined spacing in the radial direction of the magnetic disk. The at least one region of the surface of the magnetic disk includes flat areas between the protrusions. At least some of the flat areas extend continuously from an inner redius of the at least one region of the surface of the magnetic disk to an outer radius of t he at least one region of the surface of the magnetic disk.

Magnetic disk including protective layer having surface with protrusions, and substrate therefor

There is provided a magnetic disk apparatus comprising: at least one magnetic disk having a magnetic layer and a surface protective layer on a substrate; a magnetic head which faces the magnetic disk in a rotating state with a micro gap and is supported by a slider; rotating means for rotating the magnetic disk; and a actuator for moving and positioning the magnetic head to a predetermined position on the magnetic disk, wherein a plurality of protrusions each having a flat surface are formed in at least a region on the surface of the magnetic disk where a contact start/stop operation can be executed. According to the above magnetic disk apparatus, since the frictional force between the disk and the head is small and the flying height of the head can be reduced and the good floating stability is obtained, so that the excellent recording and reproducing characteristics are derived. Further, protrusions are formed on the protective layer of the magnetic disk and the protrusion shapes are changed in a accordance with a radial position of the magnetic disk depending on the flying height of the magnetic head. According to the above magnetic disk apparatus, since the change of spacing can be set smaller than the change of the flying height, high recording density can be achieved.

Magnetic disk including protective layer having surface with magnetic

To provide a magnetic disk excellent in floating and sliding characteristics in a low floating area. A magnetic disk having a feature that variations in the height of the projections on each surface of protective films in floating ensured areas on both sides of the magnetic disk are .+-.15%, and a magnetic disk device on which the magnetic disk is mounted. A surface processing apparatus for a magnetic disk, including: a first electrode for fixing the magnetic disk, the first electrode having an inside diameter larger than the inside diameter of the non-magnetic substrate; an electrically grounded shield for shielding the first electrode; a second electrode, disposed in parallel to the surface of the magnetic disk, for generating plasma against the surface of the magnetic disk; and a plasma control member, disposed at a position separated from the outer edge of the magnetic disk by a specified distance, for controlling plasma generated against the surface of the magnetic disk; wherein a power is applied between the first and second electrodes for plasma-etching the surface of the magnetic disk.

Magnetic disk and method of and apparatus for manufacturing magnetic disk

This invention relates to the magnetic recording medium, its manufacturing method and the magnetic disk apparatus, in which the ferromagnetic thin film is formed on the substrate board, and the protective layer is provided on that. A Magnetic recording medium of the has at least one layer of the protective layer on the magnetic surface, which is characterized in that the surface of the protective layer is provided with the high noncontinuous large resistance layer, and the density of the surface of the protective layer is higher than other regions other than the said surface. The magnetic recording medium has the surface of the protective layer which contains at least one kind or more of the element of the inert gas element, the halogen element and hydrogen. Therefore, when making a lower flying height of the magnetic head is achieved, the slide durability over the long term is improved, particularly, the slide durability of the magnetic disk apparatus using the MR head can be improved.

Magnetic recording medium comprising a protective layer having specified

A magnetic recording medium excellent in corrosion resistance and rubbing reliability is realized by forming a number of concavities and convexities on the surface of a protective layer formed on a substrate and applying dry etching with a noble gas after the formation of the concavities and convexities to form a modified layer having hydrophobic nature on the surface of the protective layer.

Magnetic recording medium and process for producing same

A magnetic disk has a magnetic layer and a protective layer disposed on the magnetic layer. A multiplicity of lands having sizes within a predetermined range of sizes and generally equal heights within a predetermined range are formed on the surface of the protective layer at a density within a predetermined range. The lands serve to effectively remove contaminants attached to the floating surface of a magnetic head to ensure a desired sliding reliability and floating stability of the head during a long period of time even in the case of a high-density magnetic disk apparatus in which the extent of floating of the head is small. The reliability with which the magnetic disk apparatus operates is thereby improved. The lands are formed on the surface of the protective layer by a process of forming a mask of fine particles on the protective layer surface and etching the protective layer surface through this mask.

Magnetic disk, method of manufacturing the same and magnetic disk

Magnetic disk including protective layer having surface with protusions

A method of forming projections on major surfaces of a disk comprises the steps of supporting the disk in a space, spraying a multiplicity of fine solid particles into the space, charging the sprayed fine solid particles with electricity of the same polarity so that the fine solid particles are floating in the space in a mutually separated state due to electric repellent forces acting between the fine solid particles, electrostatically depositing the fine solid particles charged with electricity on the surfaces of the disk, and etching the disk surfaces by using the deposited fine solid particles as masks, thereby forming a multiplicity of projections on the disk surfaces.

Magnetic disk manufacturing method

A magnetic disk medium in which texture working is performed on surfaces of a substrate or on surfaces of subbing films provided on the substrate to attain circumferential worked-traces so that the contact start stop area thereof is different from the recording/reproducing area thereof in roughness of the worked surfaces.

Magnetic disk medium with circumferentially textured surfaces and varied

A method of data compression for recording data on a recording medium such as a magentic tape, a method of data restoration for data which has been compressed for recording, and an apparatus of data compression and restoration prescribe the data to be compressed based on type or value and encode the compression object data, thereby reducing the number of bits necessary to indicate the compression object data. Compression is implemented only for consecutive data fewer in number of repeating consecutive bytes than a certain number, thereby reducing the number of bits necessary to indicate the number of bytes of the consecutive data. A compression mark indicative of compression is appended to the compressed data, consisting of data made by encoding the compression object consecutive data and data indicating the number of bytes of the data, either at the front or rear of the compressed data, whereby an input data string can be compressed drastically and compressed data, even including errors, can be restored.

Method and apparatus for data compression and restoration

In a superprecision lathe of the present invention, a main spindle having mounted at one end thereof a vacuum chuck rotatably supported in an air bearing fixed on a headstock. There is formed within the main spindle a first vacuum passage connected to the vacuum chuck and opened at the outer surface of the main spindle, and a second vacuum passage formed in the headstock and of which an open end to be connected to a vacuum pump and is opened at the inner surface of the air bearing. The first vacuum passage is connected to the second vacuum passage through an interconnection region defined by two annular grooves formed at the opposite positions of the outer surface of the main spindle and the inner surface of the air bearing; therefore, it is not necessary to use a specific sealing member, any external vibration is not transmitted to the main spindle, and the object can be worked effectively with a high speed rotation of the main spindle.

Superprecision lathe

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Odawara, Japan

Hiroshi Yashiki