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:
Aug. 27, 1996
Filed:
Apr. 29, 1993
Li Li, Gloucester, CA;
National Research Council of Canada, Ottawa, CA;
Abstract
The prevention of counterfeiting of currencies, passports, cheques, bank cards, credit cards, optical disks and the like is addressed by introducing thin film structures having both optically-variable security properties and encoded optical data decodable by optical means. The thin film structures comprise a substrate and a multilayer interference coating carried by the substrate, producing an inherent color shift with a change of viewing angle. The multilayer interference coating has a dielectric material which is transparent and the recording layer made of a light absorbing material, a crystalline-structural changing material or a magneto-optic material. The encoded data is in the form of bar codes or digital data. The information is encoded by photolithographic means or by optical recording means. The encoded data is retrieved by an optical recording system having a light source and an optical guiding system and a light detector.