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. 17, 2013
Filed:
Feb. 14, 2012
Tomoto Kawamura, Yokohama, JP;
Kotaro Oishi, Fujisawa, JP;
Masayuki Kobayashi, Kuki, JP;
Hideo Suenaga, Yokohama, JP;
Tomoto Kawamura, Yokohama, JP;
Kotaro Oishi, Fujisawa, JP;
Masayuki Kobayashi, Kuki, JP;
Hideo Suenaga, Yokohama, JP;
Hitachi Media Electronics Co., Ltd., Iwate, JP;
Abstract
An optical disc device includes an optical source for emitting an optical beam, an incident intensity control circuit for controlling an intensity of the optical beam emitted from the optical source, an objective lens for focusing the optical beam on an optical disc, an optical detector for receiving the optical beam reflected from the optical disc, and a servo signal generation circuit for generating a focus error signal from the optical detector, by this configuration, the optical beam is varied once to a third optical beam intensity to be present in between a first optical beam intensity and a second optical beam intensity when varying from the first optical beam intensity up to the second optical beam intensity different from the first optical beam intensity, and the incident intensity control circuit is controlled such that the variation of focus error signal is not exceeded over a predetermined range.