Patents by Inventor Kikuo Oonuma

Kikuo Oonuma 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).

  • Magnetic recording medium comprising upper and lower magnetic layers
    Patent number: 5084335
    Abstract: A magnetic recording medium improved in the magnetic recording characteristics, running properties and durability is disclosed. The magnetic recording medium comprises a non-magnetic support having on a side of the support an upper magnetic layer positioned farther from the support and a lower magnetic layer positioned closer to the support. The upper magnetic layer comprises a binder, a magnetic powder having an original BET specific surface area of not less than than 30 m.sup.2 /g and at least one abrasive selected from alumina, silicon carbide, Cr.sub.2 O.sub.3, silica, .alpha.-Fe.sub.2 O.sub.3, TiO.sub.2 and zilconia in a portion of 3 to 20 parts per 100 parts by weight of the magnetic powder, and the lower magnetic layer comprises a binder and a magnetic powder having an original BET specific surface area of less than 30 m.sup.2 /g, and kinds of the binders each contained in the upper magnetic layer and the lower magnetic layer are the same.
    Type: Grant
    Filed: September 14, 1989
    Date of Patent: January 28, 1992
    Assignee: Konica Corporation
    Inventors: Yasushi Nakano, Setsuko Kawahara, Kikuo Oonuma, Masahiro Umemura, Seiichi Tobisawa, Takeshi Nakajima