Patents by Inventor Kouei Usuda

Kouei Usuda 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: 5414567
    Abstract: A magnetic recording method and apparatus which performs a quadrature phase shift keying operation on a digital information signal, superimposes a high frequency bias signal on the performed signal, records the resulting signal into a deep portion of a magnetic layer of a magnetic tape with a first rotational head, and records a video signal in a surface portion of the magnetic layer above a track formed by the former recording, with a second rotational head which is different in azimuth angle from the first rotational head, the frequency of the high frequency bias signal being set to a value which is about four times as high as the carrier frequency of the quadrature phase shift keyed digital information signal, thereby eliminating a 5th-order distortion component due to cross modulation of the high frequency bias signal and the carrier frequency.
    Type: Grant
    Filed: December 11, 1990
    Date of Patent: May 9, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Nobutaka Amada, Toshifumi Takeuchi, Akira Abeta, Takao Arai, Kouei Usuda