Patents by Inventor Takesi Maeda

Takesi Maeda 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: 4067044
    Abstract: An information signal is recorded on information tracks wobbling along concentric circles or a spiral line on a recording disc in superposed relation with a standard signal whose frequency varies depending on the recorded position on the disc. Desired information can be selectively reproduced accurately at a high speed by applying an external signal having the same frequency as that of the standard signal recorded on the recording disc together with the desired information, comparing the frequency of the standard signal being reproduced with that of the externally applied signal, selecting the desired information track on the basis of the result of frequency comparison for reproducing the desired information, and after the selection of the desired information track, carrying out fine tracking control while comparing the envelope of the reproduced information signal with the reproduced standard signal, so that the reproducing beam spot can accurately track the desired information track.
    Type: Grant
    Filed: February 3, 1976
    Date of Patent: January 3, 1978
    Assignee: Hitachi, Ltd.
    Inventors: Takesi Maeda, Mahito Kohmoto, Seiji Yonezawa