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. 14, 2010
Filed:
Sep. 28, 2005
Jun-ichi Asada, Kobe, JP;
Seiji Nishiwaki, Kobe, JP;
Kazuo Momoo, Hirakata, JP;
Panasonic Corporation, Osaka, JP;
Abstract
There is provided, in an optical disk apparatus which is capable of recording data to or reading data from a plurality of types of optical disks, a wavelength plate and an optical pickup which can reduce deterioration in signal quality even in the presence of a large birefringence of the substrate of an optical disk. A wavelength plateaccording to the present invention is a wavelength plate to be placed in an optical path through which rays of a plurality of wavelengths travel back and forth, the plurality of wavelengths including a ray having a wavelength λ. The wavelength plate includes a two-dimensional array of a plurality of birefringent regions, the birefringent regions including first regions Dand second regions Dhaving different optic axis directions from each other. The relationship 240°≦Δ≦300° is true, where Δis a retardation of the wavelength platefor the ray of the wavelength λ.