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. 11, 2006
Filed:
Nov. 25, 2002
Yuji Fujita, Nagano, JP;
Kenichi Hayashi, Nagano, JP;
Yoshifusa Miyasaka, Nagano, JP;
Takahiro Azuma, Nagano, JP;
Tetsuro Okamura, Nagano, DE;
Yuji Fujita, Nagano, JP;
Kenichi Hayashi, Nagano, JP;
Yoshifusa Miyasaka, Nagano, JP;
Takahiro Azuma, Nagano, JP;
Tetsuro Okamura, Nagano, DE;
Sankyo Seiki Mfg. Co., Ltd., Nagano, JP;
Abstract
An optical head device that converges first and second laser beams having different wavelengths on recording surfaces of first and second optical recording media through a single light converging optical system including an objective lens for recording or reproducing data on the recording surfaces. A refracting surface of the objective lens is divided into two regions, i.e., a central refracting surface region with an optical axis thereof being as a center and an outer circumferential refracting surface region that surrounds an outer circumference of the central refracting surface region. A diffraction grating is formed generally entirely over the central refracting surface region. When recording or reproducing data on the first optical recording medium using the first laser beam, a beam spot is formed with a diffracted beam obtained by the central refracting surface region. When recording or reproducing data on the second optical recording medium using the second laser beam, a beam spot is formed with a beam portion that passes the outer circumferential refracting surface region and a diffracted beam obtained by the central refracting surface region.