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:
Aug. 23, 2011
Filed:
Jul. 13, 2007
Masakazu Ogasawara, Tsurugashima, JP;
Takuma Yanagisawa, Tsurugashima, JP;
Katsuhiro Koike, Kawasaki, JP;
Masakazu Ogasawara, Tsurugashima, JP;
Takuma Yanagisawa, Tsurugashima, JP;
Katsuhiro Koike, Kawasaki, JP;
Pioneer Corporation, Tokyo, JP;
Abstract
A pickup device includes an irradiation optical system including an object lens for focusing light flux on a track of a recording surface of an optical recording media having a plurality of recording layers stacked while a spacer layer is interposed between the recording layers to form a spot and a detection optical system including an photo detector having a plurality of light receiving parts for receiving returning light reflected from the spot through the object lens to perform photoelectric conversion. The pickup device controls a position of the object leans according to an electrical signal calculated from outputs of the light receiving parts. The pickup device further includes an astigmatic device for providing astigmatism to the returning light directed to the light receiving parts and a division device, having divisional regions divided by a division line extending in an astigmatic direction about an optical axis of the returning light, for dividing the returning light having the astigmatism into a plurality of partial light fluxes divided for the respective divisional regions along the optical axis of returning light. The neighboring divisional regions provide the partial light fluxes with an optical action so that interference between the corresponding partial light fluxes does not occur on the light receiving parts.