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:
Aug. 22, 1989
Filed:
Mar. 11, 1988
Pioneer Electronic Corporation, Tokyo, JP;
Abstract
A servo circuit for use in an optical disk player or the like, which can track a disk having a large eccentrically without abnormal sampling of the RF signal produced as a result of scanning the disk. The servo circuit according to this invention comprises a first comparator for comparing RF signals from a pair wobbled pits on a optical disk and generating a difference signal indicating the level difference between the AF signals; a holding means for holding the difference signal for a predetermined period; a reference level producing circuit for setting reference levels having a predetermined width with the level of a previously sampled difference signal of the holding means as a center; a second comparator for comparing the level of a presently sampled difference signal of the first comparator with the reference level and outputting a first signal indicative of the comparative result; and a selector for selecting and outputting, as a tracking error signal, either the presently sampled difference signal and a second signal having a level within the predetermined width of the reference level in accordance with the comparative result. The presently sampled difference signal is selected when the level of the presently sampled difference signal is within the reference level and the second signal is related when the presently sampled difference signal is out of the reference level.