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:
Aug. 15, 2000
Filed:
Feb. 06, 1998
Nobuyasu Kikuchi, Chiba, JP;
Akio Yamakawa, Tokyo, JP;
Sony Corporation, Tokyo, JP;
Abstract
An objective lens, a reproducing apparatus and a reproducing method using a single objective lens for a DVD which can also read a CD without adding any peripheral member can be obtained. In an objective lens which is arranged so that a light beam emitted form a common light source (11) may be focused through a common objective lens (8) on respective signal recorded surfaces (1a), (2a) of a DVD (2) and a CD (1) having light transmitting layers (1c), (2c) of different thicknesses, an area of the objective lens (8) for the DVD (2) in a range of a numerical aperture NA from 0 to 0.3-0.4 from the light axis is worked to form correcting lens surface 8a for correcting the aberration caused when reading the CD (1) through the objective lens for the DVD (2), thereby allowing the CD to be read through the objective lens for the DVD.