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. 11, 2011
Filed:
Jul. 12, 2010
Eriko Tatsu, Kokubunji, JP;
Tatsuro Ide, Kawasaki, JP;
Shigeharu Kimura, Yokohama, JP;
Kazuyoshi Yamazaki, Yamato, JP;
Eriko Tatsu, Kokubunji, JP;
Tatsuro Ide, Kawasaki, JP;
Shigeharu Kimura, Yokohama, JP;
Kazuyoshi Yamazaki, Yamato, JP;
Hitachi Media Electronics Co., Ltd., Iwate-ken, JP;
Abstract
An optical pick-up which permits the relative position of a diffracting optical element and a photodetector to be adjusted by feedback control with signals which are generated when more than one kind of diffracted light differing in order is received, the diffracted light occurring as the reflected light from the optical disc is divided and diffracted by the diffracting optical element having multiple regions. The photodetector which detects the light beam passing through the central region of the diffracting optical element and generates RF signals is juxtaposed with sub-photodetectors, so that they receive reflected stray light from out-of-focus layers and perform computation to calculate the reflected stray light component which the RF signal detector receives, thereby detecting only the component of signals of the reflected light from a target layer.