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:
May. 10, 2011
Filed:
Jul. 18, 2007
Naoto Shimada, Hyogo, JP;
Hiroaki Yamamoto, Hyogo, JP;
Naoki Nakanishi, Shiga, JP;
Masahiko Nishimoto, Osaka, JP;
Takuya Okuda, Kyoto, JP;
Naoto Shimada, Hyogo, JP;
Hiroaki Yamamoto, Hyogo, JP;
Naoki Nakanishi, Shiga, JP;
Masahiko Nishimoto, Osaka, JP;
Takuya Okuda, Kyoto, JP;
Panasonic Corporation, Osaka, JP;
Abstract
An optical pickup device includes a diffraction gratingfor separating an emitted light beam into at least three light beams. The diffraction gratingis divided into three regions by dividing lines Dand Dextending in a first direction parallel to a tangent line of a track of an optical information recording medium. A second regionB is divided into four sub-blocks by a dividing line Dextending in the first direction and a dividing line Dextending in a second direction that crosses the first direction. The sub-blocks located diagonally opposite to each other have a same phase, and the sub-blocks located adjacent to each other have a phase difference of approximately 180 degrees. The first regionA has a phase difference of approximately 90 degrees from each sub-block of the second regionB, and the first regionA has a phase difference of approximately 180 degrees from the third regionC.