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. 14, 2015
Filed:
Nov. 26, 2012
Masayuki Omaki, Tokyo, JP;
Kenya Nakai, Tokyo, JP;
Nobuo Takeshita, Tokyo, JP;
Mitsubishi Electric Corporation, Tokyo, JP;
Abstract
An optical head device () provided with: an optical element () for transmissively diffracting a light beam emitted from a semiconductor laser (), generating a zero-order diffracted light beam and ±1-order diffracted light beams; and a photodetector () for receiving the zero-order diffracted light beam and the +1-order diffracted light beam after reflection from an optical disc (). The photodetector () includes a primary light receiving section () for receiving the zero-order diffracted light beam, and a first secondary light receiving section () disposed outward from the primary light receiving section (). The first secondary light receiving section () is positioned to detect an outer portion of the received light spot of the +1-order diffracted light beam, performs photoelectric conversion of this portion, and outputs a secondary detected signal.