Patents by Inventor Shinei Ryu

Shinei Ryu 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).

  • Perpendicular magnetic recording medium
    Patent number: 4966821
    Abstract: A perpendicular magnetic recording medium is disclosed, which comprises a substrate, a soft magnetic layer formed on the substrate, a lower recording layer having a coercive force of Hcl formed on the soft magnetic layer, and an upper recording layer having a coercive force of Hcu, with the coercive ratio of Hcu/Hcl being in the range of 1.4 to 3.3, that is, 1.4.ltoreq.Hcu/Hcl.ltoreq.3.3.
    Type: Grant
    Filed: June 27, 1989
    Date of Patent: October 30, 1990
    Assignees: Ricoh Company, Ltd., Ricoh Research Institute of General Electronics Co., Ltd.
    Inventors: Ikue Kawashima, Futoyoshi Koh, Masafumi Kumano, Shinei Ryu