Patents by Inventor Tetsuo Usui

Tetsuo Usui 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: 5682372
    Abstract: There is disclosed a method of playing back information from an optical multilayer disk having a plurality of recording disks stacked on top of each other, by the use of an optical pickup device. In order to switch the focused recording layer from a first one to a second one so that data is read from the second recording layer, the focus balanced condition of the pickup device is switched from a setting providing a focus error characteristic adapted for the first recording layer to a reference setting providing a neutral focus error characteristic. Then, the focal point of the pickup device is moved from the first recording layer. Subsequently, the pickup device is focused onto the second recording layer, and data is read from the second recording layer. Thereafter, the focus balanced condition of the pickup device is switched to a setting adapted to the second recording layer.
    Type: Grant
    Filed: August 15, 1996
    Date of Patent: October 28, 1997
    Assignee: Sony Corporation
    Inventors: Akio Yamakawa, Tetsuo Usui, Masamichi Utsumi