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. 25, 2012
Filed:
May. 25, 2009
Hirotaka Miyamoto, Kanagawa, JP;
Kimihiro Saito, Saitama, JP;
Kunihiko Hayashi, Kanagawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
Disclosed is an optical disc device that is able to increase accuracy in reproducing information from an optical disc. The optical disc devicecalculates a focus error signal SFEand a sum signal SSwhile reciprocating an objective lensin a focus direction until a distance between a focal point FS and a focal point FMbecomes close to the depth d of a target position PG at the time of a pull-in operation, and when a trigger signal STgenerated on the basis of the sum signal SSis at low level, starts focus control on the basis of the focus error signal SFE. Therefore, focus control can start in a state where the focus error signal SFEcurves in an S shape with sufficient amplitude.