Patents by Inventor Kenji Maebara

Kenji Maebara 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).

  • Focus optical system and optical disc master exposure apparatus
    Patent number: 7933189
    Abstract: In a focus optical system for optical discs or optical disc master exposure apparatuses, a relative positional relation between a cylindrical lens and a 4-division detector in an astigmatic optical system is adjust so that an interference fringe appearing in reflected light derived from an optical disc master is made to be incident on a dead zone of the 4-division detector. Thus, an astigmatic focus servo free from effects of variations in a focus error signal due to the interference fringe is realized. As a result of this, effects of the interference fringe appearing in the reflected light derived from an optical disc or optical disc master can be suppressed.
    Type: Grant
    Filed: April 15, 2009
    Date of Patent: April 26, 2011
    Assignee: Panasonic Corporation
    Inventors: Takeshi Omori, Takaaki Kassai, Kenji Maebara, Keiji Fujita, Hiroaki Ashiwa
  • FOCUS OPTICAL SYSTEM AND OPTICAL DISC MASTER EXPOSURE APPARATUS
    Publication number: 20090262634
    Abstract: In a focus optical system for optical discs or optical disc master exposure apparatuses, a relative positional relation between a cylindrical lens and a 4-division detector in an astigmatic optical system is adjust so that an interference fringe appearing in reflected light derived from an optical disc master is made to be incident on a dead zone of the 4-division detector. Thus, an astigmatic focus servo free from effects of variations in a focus error signal due to the interference fringe is realized. As a result of this, effects of the interference fringe appearing in the reflected light derived from an optical disc or optical disc master can be suppressed.
    Type: Application
    Filed: April 15, 2009
    Publication date: October 22, 2009
    Inventors: Takeshi OMORI, Takaaki KASSAI, Kenji MAEBARA, Keiji FUJITA, Hiroaki ASHIWA