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:
Jul. 06, 2010
Filed:
Sep. 06, 2007
Takuya Okuda, Kyoto, JP;
Hiroaki Yamamoto, Hyogo, JP;
Naoki Nakanishi, Shiga, JP;
Masahiko Nishimoto, Osaka, JP;
Naoto Shimada, Hyogo, JP;
Takuya Okuda, Kyoto, JP;
Hiroaki Yamamoto, Hyogo, JP;
Naoki Nakanishi, Shiga, JP;
Masahiko Nishimoto, Osaka, JP;
Naoto Shimada, Hyogo, JP;
Panasonic Corporation, Osaka, JP;
Abstract
A pickup device includes a diffraction gratingfor separating a light beam emitted from the light source into at least three light beams. The diffraction gratingis divided into four regions by straight lines extending in a direction parallel to a tangential direction of tracks of an optical information recording medium. A periodic structure of a second regionB has a phase difference of approximately 180 degrees from a periodic structure of a third regionC, and a periodic structure of a first regionA has a phase difference of approximately 180 degrees from a periodic structure of a fourth regionD.