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:
Feb. 24, 1981
Filed:
Dec. 11, 1978
Willem G Opheij, Eindhoven, NL;
Jan E van der Werf, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
An apparatus is described for reading a record carrier with an optical radiation-reflecting information structure. The path of the read beam includes a plane-parallel plate, whose surface area is substantially smaller than the cross-sectional area of the read beam, which plate ensures that the beam portion which passes through the plate cannot interfere with the rest of the read beam. After reflection by the record carrier the said beam portion passes through the radiation-deflecting element which deflects the beam portion to two radiation-sensitive detectors. The position of the radiation spot formed by the said beam portion is proportional to the degree of focussing of the read beam on the information structure.