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. 27, 2007
Filed:
Apr. 18, 2003
Tetsuo Ueyama, Nara, JP;
Keiji Sakai, Nara, JP;
Renzaburou Miki, Soraku-gun, JP;
Osamu Miyazaki, Soraku-gun, JP;
Yukio Watanabe, Uji, JP;
Tetsuo Ueyama, Nara, JP;
Keiji Sakai, Nara, JP;
Renzaburou Miki, Soraku-gun, JP;
Osamu Miyazaki, Soraku-gun, JP;
Yukio Watanabe, Uji, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
An optical pickup converts a laser beam from a semiconductor laser () into a parallel ray with a collimator lens (), and divides it into a main beam (), a sub-beam (+1st order component) (), and a sub-beam (−1st order component) () with a gradient multiple-division type phase difference grating (). After passing through a beam splitter (), an objective lens () condenses the light beams on a track () of an optical disc (), and the reflected light that has passed through the objective lensis reflected at the beam splitter () and is guided into optical detectors (A,B, andC) by a condensing lens (). Accordingly, in a tracking error signal detecting method using the push-pull signals of the main beam and sub-beams, an offset produced by an objective lens shift or a disc tilt can be cancelled at low cost without lowering the efficiency of using light.