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:
May. 09, 2006
Filed:
Jun. 28, 2002
Yoichi Tsuda, Yamatotakada, JP;
Yoichi Tsuda, Yamatotakada, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
An object of the present invention is to provide an optical pickup apparatus which changes characteristics of a light-emitting device or hologram to reduce problems of track servo deviation due to scratches on a surface of an optical disc. By aligning a photoreceptive domain for focusing error signal (PDf) and a photoreceptive domain for tracking error signal (PDt), even in a case where scattering light made by a scratch in the tangent direction of a track of an optical disc reaches the photoreceptive domains, light diffracted in a HA+B domain of a hologram pattern does not enter into photoreceptive portion F or G of the PDt. Therefore, scattering of light which enters the PDf does not influence a tracking error signal (TES), so that the TES does not become abnormally large, and track servo deviation can be prevented.