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. 03, 2011
Filed:
Feb. 22, 2010
Tomoto Kawamura, Tokyo, JP;
Kunikazu Ohnishi, Yokosuka, JP;
Masayuki Inoue, Yokohama, JP;
Katsuhiko Izumi, Kamakura, JP;
Tomoto Kawamura, Tokyo, JP;
Kunikazu Ohnishi, Yokosuka, JP;
Masayuki Inoue, Yokohama, JP;
Katsuhiko Izumi, Kamakura, JP;
Hitachi Media Electronics Co., Ltd., Iwate, JP;
Abstract
The present invention provides a photodetector capable of generating highly accurate tracking and focusing error signals free of variations in light quantity caused by interference, in an optical pickup with a two-wavelength multilaser. The photodetector comprises first three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a first wavelength and second three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a second wavelength longer than the first wavelength. The distance between both-end light receiving areas out of the first three light receiving areas is longer than the distance between both-end light receiving areas out of the second three light receiving areas.