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:
Apr. 03, 2001
Filed:
Feb. 23, 1998
Yasuaki Inoue, Nagaokakyo, JP;
Takenori Goto, Moriguchi, JP;
Atsushi Tajiri, Mishima-gun, JP;
Kazushi Mori, Hirakata, JP;
Minoru Sawada, Yawata, JP;
Akira Ibaraki, Hirakata, JP;
Sanyo Electric Co., Ltd., Moriguchi, JP;
Abstract
First and second photodiodes are arranged on the upper surface of a stem, returned light beams diffracted in the + 1st order by a transmission type holographic optical element are received by the first photodiode, while returned light beams diffracted in the − 1st order are received by the second photodiode. The first photodiode has a plurality of light receiving regions, and respectively outputs a reproducing signal, a focus error signal and a tracking error signal on the basis of the returned light beams. On the other hand, the second photodiode has a single light receiving region, and outputs a reproducing signal on the basis of the returned light beams.