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:
Jun. 25, 2013
Filed:
Jan. 17, 2011
Masahisa Shinoda, Tokyo, JP;
Hironori Nakahara, Tokyo, JP;
Masayuki Omaki, Tokyo, JP;
Kenya Nakai, Tokyo, JP;
Nobuo Takeshita, Tokyo, JP;
Masahisa Shinoda, Tokyo, JP;
Hironori Nakahara, Tokyo, JP;
Masayuki Omaki, Tokyo, JP;
Kenya Nakai, Tokyo, JP;
Nobuo Takeshita, Tokyo, JP;
Mitsubishi Electric Corporation, Tokyo, JP;
Abstract
An optical head device mounted in an optical disc device. The optical head device is provided with a diffractive optical element and a photodetector. The diffractive optical element has: a primary diffraction region at a location on which the positive and negative first-order components and some of the zero-order component of a reflectively diffracted light beam are incident; and secondary diffraction regions at locations on which the rest of the zero-order component but none of the positive or negative first-order components of the reflectively diffracted light beam are incident. A main light-receiving section of the photodetector receives the zero-order component of a transmissively diffracted light beam that has passed through the primary diffraction region and the secondary diffraction regions. Secondary light-receiving sections receive the positive first-order component and/or the negative first-order component of the transmissively diffracted light beam that has passed through the secondary diffraction regions.