Patents by Inventor Kunikazu Oonishi

Kunikazu Oonishi 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: 5295125
    Abstract: There is disclosed an optical head device in which at least two laser beams having different wavelengths are converged as light spots on a recording medium or optical disk by use of one objective lens and one of the two laser beams is subjected to a focusing control while the recording or reproduction of a signal on or from the optical disk is made using the other laser beam. When the one laser beam is subjected to the focusing control, the deviation of a converging position of the other laser beam for the optical disk may occur due to a difference in refractive index between transparent substrates of plural kinds of optical disks. In such a case, the converging position of the other laser beam is displaced to cancel the amount of deviation.
    Type: Grant
    Filed: February 2, 1993
    Date of Patent: March 15, 1994
    Assignee: Hitachi, Ltd.
    Inventors: Kunikazu Oonishi, Tohru Sasaki, Masayuki Inoue, Yasuo Kitada, Akira Saito