Hitachi, Ltd.

Babcock-hitachi Kabushiki Kaisha

Kenichi Gomi

Hideaki Tanaka

Yoshiki Kato

Youichi Inomata

Hiroshi Yashiki

Masaki Ohura

Yoshihiko Miyake

Yoshihiro Moriguchi

Sigeru Sano

Yukio Hishinuma

Norio Arashi

Hidetoshi Akimoto

Shoichi Sawahata

Kiyoshi Hashimoto

Fumito Nakajima

Noriaki Okamoto

Shinsuke Higuchi

Norikazu Tsumita

Fuminori Ishikawa

Sadao Takahashi

Nobuo Nakagawa

Toyoji Okuwaki

Nobuyuki Ishii

Hiroyuki Sugimoto

Takeo Komuro

Osamu Kanda

Hajime Iinuma

Katuo Uda

Maki Kondo

Hiroko Saito

Toshinori Hirano

In a magnetic disk unit, in the control of a load/unload function of a magnetic head relative to a magnetic disk, the magnetic disk and the magnetic head are prevented from contacting each other and damage thereto is avoided by utilizing a shallow dual-step subambient pressure slider and carrying out loading/unloading at a rotational speed lower than a rated rotational speed of the normally operated magnetic disk at which writing and reading (R/W) of data to and from the magnetic disk by the magnetic head is normally carried out.

Control method of control magnetic disk unit and magnetic disk unit using such method

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

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

There is provided a magnetic disk apparatus including 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 magnetic head positioning means 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, an area ratio of the protrusions per 1 mm.sup.2 lies within a range from 0.1 to 80%, a height of the protrusion of the maximum height among the protrusions lies within a range from 5 to 40 nm, and the magnetic layer is formed on the whole surface on the base plate. According to the above magnetic disk apparatus, the frictional force between the disk and the head is small, and the floating height of the head can be reduced, and good floating stability is obtained, so that excellent recording and reproducing characteristics are obtained.

Magnetic disk with surface protective layer having convex portions and

Sulfur oxides contained in the flue gas from coal-fired boiler are adsorbed by an adsorbent prepared by dry-distilling a portion of fuel coal, thereby producing semi-coke, and activating the semi-coke by steam, and then the sulfur oxides-adsorbed adsorbent is heated to desorb the adsorbed sulfur oxides at a high concentration. The desorbed sulfur oxides are passed through a bed of semi-coke before the activation to recover the sulfur oxides as elemental sulfur.

Process for dry desulfurization of flue gas

Sulfur oxides contained in the flue gas from coal-fired boiler are adsorbed by an adsorbent prepared by dry-distilling a portion of fuel coal satisfying at least one of requirements of an ash content lower than 15% by weight and a fixed carbon content of at least 50% by weight, thereby producing semi-coke, and activating the semi-coke by steam, and then the sulfur oxides-adsorbed adsorbent is heated to desorb the adsorbed sulfur oxides at a high concentration. The desorbed sulfur oxides are passed through a bed of semi-coke before the activation to recover the sulfur oxides as elemental sulfur.

Growing community of inventors

Hitachi, Japan

Kenichi Gomi