Patents by Inventor Yuji Shimonaka

Yuji Shimonaka 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).

  • Optical rotary encoder having at least one zone plate
    Patent number: 6020585
    Abstract: In an optical rotary encoder, a stationary plate having a zone plate and a rotary slit plate having slits are interposed between a light source and a light receiving element. A suitable radius of the innermost circle of the zone plate is selected so that the zone platess provide a sufficient convergence of light for reduction of silt interval (hence for improvement of the detection precision) with a distance between the stationary plate and the rotary slit plate maintained at a value permitting the fabrication of the encoder.
    Type: Grant
    Filed: March 27, 1998
    Date of Patent: February 1, 2000
    Assignee: Koyo Seiko Co., Ltd.
    Inventors: Yuji Shimonaka, Tatsuo Matsushima, Yasuichi Fujimoto