The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 01, 1992
Filed:
Nov. 22, 1988
Katsumi Takeda, Yokohama, JP;
Tadashi Saitoh, Fujisawa, JP;
Takashi Takeuchi, Fujisawa, JP;
Junichi Iida, Yokohama, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
In an apparatus for tracking an optical disc, speed in acquiring a steady tracking condition is significant. That is, if the light beam is subjected to feedback while it is positioned in a positive feedback region, e.g., in the middle of adjoining tracks, the track servo system causes an oscillation. Therefore, according to the present invention, there is effected a comparison between the magnitude of signals from two pits disposed offset from the track and a pit on the track to determine the position of the light beam so that the tracking error signal may be inversed when the light beam is positioned in the middle of adjoining tracks. This will operate the tracking system in the negative feedback region to more quickly achieve a stable tracking state.