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:
Jan. 20, 2009
Filed:
Jun. 30, 2004
Fumio Isshiki, Yokohama, JP;
Kunikazu Ohnishi, Yokosuka, JP;
Nobuyuki Maeda, Yokohama, JP;
Takahiro Kurokawa, Fujisawa, JP;
Takeshi Shimano, Tokorozawa, JP;
Fumio Isshiki, Yokohama, JP;
Kunikazu Ohnishi, Yokosuka, JP;
Nobuyuki Maeda, Yokohama, JP;
Takahiro Kurokawa, Fujisawa, JP;
Takeshi Shimano, Tokorozawa, JP;
Hitachi Media Electronics Co., Ltd., Mizusawa-shi, JP;
Abstract
A rewritable optical disk apparatus, optical information recording and reproducing apparatus or the like is allowed to automatically and properly adjust the optical system to the optimum focal condition regardless of the readout signal detector's positional error and the residual aberration in the optical system. The spherical aberration and defocus are coarsely adjusted using the amplitude (PP amplitude) of the tracking error signal and then finely adjusted using the amplitude (RF amplitude) of the readout signal. Since the spherical aberration can properly be adjusted, it is possible to raise the reliability of the readout signal.