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:
Sep. 11, 2012
Filed:
Apr. 05, 2007
Shuichi Takeuchi, Saitama, JP;
Shuichi Takeuchi, Saitama, JP;
Hoya Corporation, Tokyo, JP;
Abstract
There is provided an optical disc drive, which includes a light source emitting a light beam, a beam dividing element that divides the light beam into main and sub-beams, an objective lens, an astigmatism producing unit that gives astigmatism to the main and sub-beams, a signal generation unit that has sensors for the beams and generates a focus error signal based on output signals of the sensors; and an optical element that has a function of adjusting intensity distribution of the main beam such that the main beam incident on the optical disc has a predetermined intensity distribution where a maximum intensity level is positioned at a predetermined height within a range of 70% of a pupil diameter, the predetermined height is not equal to an optical axis, and an intensity of the main beam decreases gradually from the predetermined height to a peripheral portion of the pupil.