Patents by Inventor Hajime Hatada

Hajime Hatada 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).

  • Tracking signal generating device and method, and magnetic recording/reproducing system
    Patent number: 6741416
    Abstract: A device and a method are provided in which stable tracking control can be carried out even in an arbitrary phase by optically reading pits provided in a disk when information is recorded on and reproduced from the disk with a magnetic head. With respect to difference signals obtained from a main beam signal and sub-beam signals obtained through three-beam type photodetectors, gain correction is executed in variable gain amplifiers, respectively, so that output signals therefrom have same amplitude levels and are different in phase by 90 degrees in a track crossing direction, and thus a tracking error signal is generated by being synthesized from the output signals. Based on the tracking error signal, tracking control is carried out.
    Type: Grant
    Filed: December 14, 2000
    Date of Patent: May 25, 2004
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Kousei Sano, Shin-ichi Kadowaki, Hajime Hatada, Ikuo Ohmura
  • Tracking signal generating device and method, and magnetic recording/reproducing system
    Publication number: 20010004304
    Abstract: A device and a method are provided in which stable tracking control can be carried out even in an arbitrary phase by optically reading pits provided in a disk when information is recorded on and reproduced from the disk with a magnetic head. With respect to difference signals obtained from a main beam signal and sub-beam signals obtained through three-beam type photodetectors, gain correction is executed in variable gain amplifiers, respectively, so that output signals therefrom have same amplitude levels and are different in phase by 90 degrees in a track crossing direction, and thus a tracking error signal is generated by being synthesized from the output signals. Based on the tracking error signal, tracking control is carried out.
    Type: Application
    Filed: December 14, 2000
    Publication date: June 21, 2001
    Applicant: Matsushita Electric Industrial Co., Ltd.
    Inventors: Kousei Sano, Shin-ichi Kadowaki, Hajime Hatada, Ikuo Ohmura