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:
Oct. 17, 1995
Filed:
May. 25, 1994
Cornelis M van Uijen, Eindhoven, NL;
Adrianus P Jongenelis, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
An optical reader for record carriers of a two types adapted for scanning with radiation beams. The information structures of the respective types are arranged in tracks. The structure of the second type has a phase structure in which effect areas alternate with intermediate areas, and is adapted for scanning with radiation of a wavelength longer than that for the first type. This reader scans both types with radiation of the first wavelength. An analog read signal is detected from radiation received from a scanned track. For reading the second type, first and second comparators supply respective detection signals if the differences between values of the read signals, separated by a given time interval, are greater than a given positive threshold or more negative than a given negative threshold. A signal recovery circuit derives a binary information signal from the first and second detection signals.