Patents by Inventor Sadatsugi Machida

Sadatsugi Machida 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: 5016234
    Abstract: In a two-laser beam optical head including first and second signal detectors for guiding emitting beams from first and second laser sources as two spots to an information medium and detecting the reflected beams from the two spots, the optical head of the present invention has the construction wherein the two laser sources are stored in one package, the emitting beams from two laser sources can be rotated together with a collimate lens with the optical axis of the collimate lens being the center in order to enable the two spots around the optical axis of a focusing lens as the center and the direction of the center line between the two spots can be changed so that the center line between the two spots is always perpendicular to the radial direction of the track on the information medium.
    Type: Grant
    Filed: June 22, 1988
    Date of Patent: May 14, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Shigeru Nakamura, Sadatsugi Machida, Takeshi Nakao, Masahiro Ojima
  • Patent number: 4873678
    Abstract: An optical head and an optical information processor using the optical head include a light source, focusing device for focusing a light beam which is emitted from the light source, on an information medium, beam separator for isolating at least part of a light beam which is reflected from the information medium, from the light beam emitted from the light source, a beam splitter including a first polarized-light separating film which is illuminated with about a half of a light beam isolated by the beam separator, and a light detecting device having a first photodetector which receives a first light beam reflected from the first polarized-light separating film, and a second photodetector which receives a second light beam passing through the first polarized-light separating film, in a state that at least one of the first and second photodetectors is separated into a pair of light detecting elements, to make it possible to detect a magneto-optical signal and a focal error signal by the same optical system.
    Type: Grant
    Filed: December 9, 1987
    Date of Patent: October 10, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Shigeru Nakamura, Sadatsugi Machida, Tsuyoshi Toda