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. 29, 2011
Filed:
Oct. 13, 2006
Takayuki Nagata, Osaka, JP;
Joji Anzai, Osaka, JP;
Hideki Aikoh, Osaka, JP;
Eishin Mori, Kyoto, JP;
Kousei Sano, Osaka, JP;
Yoshiaki Komma, Osaka, JP;
Akihiro Arai, Kyoto, JP;
Takayuki Nagata, Osaka, JP;
Joji Anzai, Osaka, JP;
Hideki Aikoh, Osaka, JP;
Eishin Mori, Kyoto, JP;
Kousei Sano, Osaka, JP;
Yoshiaki Komma, Osaka, JP;
Akihiro Arai, Kyoto, JP;
Panasonic Corporation, Osaka, JP;
Abstract
To provide an optical head to produce good servo and read signals by reducing the influence of interference by light reflected from a non-read layer of a multilayer optical disc. The head includes: a first optical system for converging light from a light source on a first or second storage layer; a second optical system for receiving and transmitting light reflected from the first layer and stray light reflected from the second layer when the light is converged on the first layer; a photodetector; and a calculator. The photosensitive areas of the photodetector output signals representing intensities of the light incident there through the second system. The reflected and stray light incident on the second system interfere with each other, and the first and second groups of areas are arranged so as to be equally affected by a variation in intensity caused by the interference. The calculator calculates the difference between sum of a first group of signals supplied from a first group of areas and that of a second group of signals supplied from a second group of areas, thereby generating a focus error signal.