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:
Feb. 05, 2008
Filed:
Apr. 25, 2003
Shinichi Yamada, Katano, JP;
Katsuya Watanabe, Nara, JP;
Yuichi Kuze, Settsu, JP;
Kenji Fujiune, Takatsuki, JP;
Kenji Kondo, Kadoma, JP;
Takashi Kishimoto, Nara, JP;
Takeharu Yamamoto, Takatsuki, JP;
Shinichi Yamada, Katano, JP;
Katsuya Watanabe, Nara, JP;
Yuichi Kuze, Settsu, JP;
Kenji Fujiune, Takatsuki, JP;
Kenji Kondo, Kadoma, JP;
Takashi Kishimoto, Nara, JP;
Takeharu Yamamoto, Takatsuki, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optical disc drive includes a light source, a lens, a focusing section, a spherical aberration corrector, a focus signal generator, a gain calculator and a processor. The focusing section forms a beam spot in a focusing state on the information storage layer of an optical disc by controlling the position of the lens. The spherical aberration corrector changes a spherical aberration with the beam spot in a focusing state according to a drive value of a driving signal supplied to the spherical aberration corrector. The focus signal generator generates a focus signal representing the focusing state of the beam spot. The gain calculator calculates a loop gain of a focus control system in response to the focus signal. The processor determines the drive value for the spherical aberration corrector by the loop gain.