Patents by Inventor Toshimi Miyao

Toshimi Miyao 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: 4506000
    Abstract: A magnetic recording medium having a non-magnetic substrate, a first magnetic layer composed mainly of magnetic powder and binder and formed on the non-magnetic substrate, and a second magnetic layer composed mainly of magnetic powder and binder and formed on the first magnetic layer is disclosed. In this case, the magnetic powder of the first magnetic layer is made of ferro-magnetic metal powder which has a specific surface area of 20 to 40 m.sup.2 /g measured according to BET adsorption method, the first magnetic layer has coercive force H.sub.c1 of 800 to 1500 Oe, residual magnetic flux density of 3000 to 5000 Gausses and a thickness of more than 2.mu., while the magnetic powders of the second magnetic layer is made of ferro-magnetic metal powder which has a specific surface area of 40 to 150 m.sup.2 /g measured according to BET adsorption method, the second magnetic layer has coercive force H.sub.c2 of 1000 to 2500 Oe, residual magnetic flux density of 2000 to 3000 Gausses and a thickness 0.1 to 2.mu.
    Type: Grant
    Filed: February 9, 1983
    Date of Patent: March 19, 1985
    Assignee: Sony Corporation
    Inventors: Isao Kubota, Kunio Kobayashi, Toshimi Miyao