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. 21, 1993
Filed:
Jan. 31, 1990
Sony Corporation, Tokyo, JP;
Abstract
A recording and/or reproducing apparatus for from an optical disk includes a tracking error signal forming device for forming a tracking error signal by taking the difference of detection output signals from at least a pair of light beam detectors provided in an optical pickup having an actuator for shifting an objective lens in a focusing direction or in a tracking direction. Also provided is, a tracking servo device for moving the objective lens in the tracking direction on the basis of the output signal from the tracking error signal forming device to effect a tracking servo, a period detection device for detecting whether the period of a tracking servo indicating a relative movement between a track on an optical disk and a light beam from the optical disk is not more than a predetermined value, and a d.c. component switching device for switching the gain of an amplifier stage stepwise, with the amplifier stage being adapted for amplifying a detection output signal of one of at least a pair of light beam detectors and supplying the amplified signal to the tracking error signal forming device. An offset eliminating device controls the d.c. component switching device to effect switching of the gain of the amplifier stage stepwise to produce compensation data compensating the offset of the tracking error signal, only when the detection output from the period detection means indicates that the traverse signal is not more than a predetermined value, with the tracking servo means being off.