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:
Mar. 25, 2008
Filed:
Oct. 02, 2003
Yuichi Kuze, Settsu, JP;
Katsuya Watanabe, Nara, JP;
Shinichi Yamada, Katano, JP;
Kosei Sano, Osaka, JP;
Yuichi Kuze, Settsu, JP;
Katsuya Watanabe, Nara, JP;
Shinichi Yamada, Katano, JP;
Kosei Sano, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
The optical disc drive reads and/or writes data from/on an optical disc having an information storage layer. In an optical disc drive, light from a light sourceis focused by a focusing section, and each of the peripheral and non-peripheral part of light reflected by the information storage layer is received by a photodetector. Then, for each part of light, the drivegenerates a focus signal and a light quantity signal, and normalizes the focus signal based on the light quantity signal. As a result, it is possible to generate a spherical aberration signal according to a quantity of spherical aberration produced at the focusing position of the light. Hence, the signal is not affected by defocusing and thus it is possible to precisely detect a spherical aberration caused by an uneven thickness of the disc and to detect a spherical aberration with high accuracy.