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:
Nov. 22, 2005
Filed:
Oct. 10, 2001
Kousei Sano, Osaka, JP;
Shin-ichi Kadowaki, Hyogo, JP;
Yoshiaki Komma, Osaka, JP;
Seiji Nishino, Osaka, JP;
Katsuhiko Yasuda, Osaka, JP;
Akihiro Yasuda, Osaka, JP;
Kousei Sano, Osaka, JP;
Shin-ichi Kadowaki, Hyogo, JP;
Yoshiaki Komma, Osaka, JP;
Seiji Nishino, Osaka, JP;
Katsuhiko Yasuda, Osaka, JP;
Akihiro Yasuda, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optical head apparatus capable of stably obtaining a detection signal of spherical aberration even with a high density optical disk. A spherical aberration error signal is obtained by: dividing the returning light from the optical disk into a transmitted light and a diffracted light; reproducing information with the transmitted light having a larger amount of light while dividing the diffracted light having a small amount of light into two regions, i.e., region near the optical axis and a region distant from the optical axis; determining amounts of focus deviation in respective regions as focus error signals; and taking the difference signal therebetween. Thus, it is possible to detect the amount of spherical aberration with the SN ratio of the information reproducing signal kept at high level.