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. 01, 1977
Filed:
Apr. 16, 1975
Gijsbertus Bouwhuis, Eindhoven, NL;
Josephus Johannes Braat, Eindhoven, NL;
Peter Ferdinand Greve, Eindhoven, NL;
Kornelis Antonie Immink, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
An apparatus is described for reading a flat record carrier on which information is stored in an optically readable track-shaped information structure. By the arrangement in the far field of the information structure and at one side of a plane which is formed by the optical axis of an objective system which is used for reading and a line parallel to the center line of the track portion to be read, of a radiation-sensitive detection system which consists of at least two detectors in approximately the position .beta./2, .beta. being the angle at which a first-order beam is diffracted in the lateral direction of the tracks, centering and focussing errors can be detected without the use of auxiliary beams and additional optical elements.