Patents by Inventor Shoichi Sawahata

Shoichi Sawahata has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5656349
    Abstract: 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.
    Type: Grant
    Filed: July 2, 1991
    Date of Patent: August 12, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Kenichi Gomi, Hideaki Tanaka, Hiroyuki Sugimoto, Shoichi Sawahata, Masaki Ohura, Yoshihiko Miyake, Yoshiki Kato, Hiroshi Yashiki, Youichi Inomata, Yoshihiro Moriguchi
  • Patent number: 5285343
    Abstract: 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.
    Type: Grant
    Filed: October 11, 1990
    Date of Patent: February 8, 1994
    Assignee: Hitachi, Ltd.
    Inventors: Hideaki Tanaka, Kenichi Gomi, Shoichi Sawahata, Maki Kondo, Masaki Ohura, Norikazu Tsumita, Katuo Uda, Yoshiki Kato, Yoshihiko Miyake, Toyoji Okuwaki, Noriaki Okamoto, Nobuo Nakagawa