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:
May. 15, 2001
Filed:
Mar. 22, 1999
Yasuo Sasaki, Kanagawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
A tracking servo device for use with an optical disc apparatus includes a photodetector unit having a plurality of photodetectors each of which is split in association with the direction of tracks formed on the optical disc, and a tracking error generating unit for finding the difference in outputs from at least two of the photodetectors of the photodetector unit for generating a tracking error signal. The tracking servo device also includes a first correction unit for removing an offset produced in the tracking error signal when the tracking servo is on, and a second correction unit for removing an offset produced in the tracking error signal when the tracking servo is off. The tracking servo device also includes a switching unit for selecting the first correction unit or the second correction unit when the tracking servo is on or off, respectively, for producing a tracking error signal freed of the offset component, and an offset holding unit for holding an offset component extracted by the second correction unit. The tracking servo device further includes a control unit for controlling the holding time of the offset component in the offset holding unit.