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:
Oct. 10, 2011
Filed:
May. 21, 2007
Shin-ichi Kadowaki, Hyogo, JP;
Yoshiaki Komma, Osaka, JP;
Kousei Sano, Osaka, JP;
Panasonic Corporation, Osaka, JP;
Abstract
An optical pickup head device includes a diffraction grating for generating zero-order diffracted light and at least first-order diffracted light and provides a tracking error signal with a DPP method. The diffraction grating includes grating patterns with a nonuniform period or phase. The size of the first-order diffracted light converged on an optical recording medium is larger in the direction parallel to a tangent to the track than in the direction perpendicular to the tangent. PPPWPWis established, where PWrepresents the power that is required to record information on the optical recording medium, PWrepresents the maximum power that allows information recorded on the optical recording medium to be reproduced without being erased, Prepresents the light amount of the zero-order diffracted light converged on the optical recording medium, and Prepresents the light amount of the at least first-order diffracted light converged on the optical recording medium. This configuration makes it possible to detect a tracking error signal with reduced offset, even if a recordable optical recording medium having two information recording planes is used.