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:
Feb. 05, 2008
Filed:
Mar. 24, 2004
Takashi Kobayashi, Kanagawa, JP;
Tadashi Taniguchi, Kanagawa, JP;
Takashi Kobayashi, Kanagawa, JP;
Tadashi Taniguchi, Kanagawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
A diffraction element is interposed between a semiconductor laser and collimator lens. Other diffracted light than zero-order light output from the diffraction element will not be focused on an optical recording medium and the amount of light condensed to the focus of the zero-order light is thus smaller. The diffraction element is variable in diffraction efficiency. When the diffraction efficiency of the diffraction element is raised, an optical pickup device will utilize the light with a lower efficiency. With the diffraction efficiency being lowered, the optical pickup device will utilize the light with a higher efficiency. Thus, the optical pickup device can utilize the light with a variable efficiency without having to being designed larger.