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. 19, 2001
Filed:
Oct. 08, 1997
Applicant:
Inventor:
Lieu Kim Dang, Villingen-Schwenningen, DE;
Assignee:
Deutsche Thomson-Brandt GmbH, Villingen-Schwenningen, DE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B 7/00 ;
U.S. Cl.
CPC ...
G11B 7/00 ;
Abstract
The present invention relates to a recording or replay device, and to a method for recognizing a focussing status. The object of the invention is to provide a method of this type and a recording or replay device, with the facility of producing significant astigmatism in the reflected light beam (,) simply and cost-efficiently without elaborate alignment. This object is achieved by the use of a birefringent element (,). The invention is, in particular, suitable for use in a recording or replay device for writing to or playing back optical recording media (,) such as CDs, video discs, DVDs and the like.