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:
Jun. 24, 2003
Filed:
Feb. 09, 2000
Tetsuo Saimi, Osaka, JP;
Seiji Nishino, Osaka, JP;
Hidenori Wada, Osaka, JP;
Teruhiro Shiono, Osaka, JP;
Keiichi Matsuzaki, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Kadoma, JP;
Abstract
An information recording and reproducing apparatus in accordance with the present invention has a radiation light source, a collimator turning a light beam emitted from the radiation light source into substantially parallel light, a light beam convergence member focusing the light beam on an information carrier, a light beam polarization-branching member branching the light beam by polarization, a variable wave plate located between the collimator and the light beam convergence member, photo detectors receiving the light beam branched by the light beam polarization-branching member and outputting a current according to an incident light quantity, and an output level judging member judging whether an output of the photo detectors is larger or smaller than a predetermined value. When the photo detectors receive a small light quantity because the information carrier is highly birefringent, the variable wave plate is switched from a ¼ wavelength plate to a zero-wave plate, thus constantly obtaining a stable reproducing signal with an excellent S/N.