Patents by Inventor Tomoji Osumi

Tomoji Osumi 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: 4807212
    Abstract: The present invention relates to an optical head of an optical disk apparatus and a method of making the same, and more particularly, to an optical head which projects a light spot onto a track recess, receives the reflected light of the light spot by at least two photoelectric converters and focuses the light spot based on a differential output from the photoelectric converters. The optical head can accurately focus the light spot even if the reflected light beams that are nonuniform in intensity due to the influence of the comatic aberration of a lens composing the optical head are projected on to the photoelectric converters. This is because the influence of the comatic aberration of the lens is corrected for by marking the direction of central parallel ones of S-like interference fringes on the lens and optically forming a predetermined angle between the marked direction and the direction of the track recess.
    Type: Grant
    Filed: March 24, 1987
    Date of Patent: February 21, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Tokuya Kaneda, Akira Saito, Masateru Watanabe, Tomoji Osumi, Nobuo Suzuki