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:
Oct. 18, 2011
Filed:
Apr. 02, 2009
Kazuyoshi Yamazaki, Yamato, JP;
Yasuo Kitada, Odawara, JP;
Kazuyoshi Yamazaki, Yamato, JP;
Yasuo Kitada, Odawara, JP;
Hitachi Media Electronics Co., Ltd., Iwate, JP;
Abstract
In the optical pickup device, while reflection light reflected from the optical multi-layer disc is divided into a plurality of regions so as to produce a plurality of divided optical beams, the divided optical beams are focused onto different positions on a photodetector, and a focus error signal is detected by employing a plurality of the divided optical beams by utilizing the knife edge method, and further, a tracking error signal is detected by employing a plurality of the divided optical beams. Furthermore, the dividing regions of the optical beam and light receiving parts are arranged in such a manner that stray light derived from other layers of the optical disc is not entered to a servo signal-purpose light receiving part of the photodetector when the divided optical beam is focused onto a target layer of the optical disc.