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:
May. 23, 1995
Filed:
Sep. 27, 1993
Louis H Liang, Los Altos, CA (US);
Daniel A Marinello, Burlington, KY (US);
William J Ryan, Underhill, VT (US);
Donald L Wray, Sunrise, FL (US);
Angstrom Technologies, Inc., Florence, KY (US);
Abstract
A system for authentication of articles uses a multiplicity of discriminating variables to characterize light detected from the articles after predetermined illumination. Articles are tested which have been marked with substances such as dye or ink that fluoresce in a region of the optical spectrum when illuminated with light in another region of the spectrum, such as the ultraviolet region. The authentication system illuminates the articles with light modulated at a frequency of more than about 50 kHz, and secondary fluorescent light returned from the articles is synchronously detected. A programmable microcomputer digitizes the synchronously detected signal and analyzes it to compare the signal with predetermined standard digital signals. The standard signals incorporate a number of discriminating features, for example the fluorescent light's wavelengths, amplitudes, and time delays relative to the modulated illuminating light. The standard signals may also incorporate spatial distributions such as bar codes as discriminating features. The discriminating features may be re-programmed by the user of the authentication system. Thus the discriminating features define a user-determined encryption of the articles' authentic identity. For applications in which the articles are stationary, the authentication system can include scanning means to scan the articles with modulated light. In other applications, the articles move past the authentication system optics and do not require scanning. In quality control applications, predetermined fluorescent substances are added in small percentages to tag other materials, which may be non-fluorescent, and the authentication system is used to provide statistical information about the presence and quantities of the tagged materials. The authentication system can include readers of visible bar codes, readers of magnetic stripe codes, or other readers of coded indicia, in addition to a reader of indicia made with fluorescent substances. Security documents having multiple fields, with at least one field bearing fluorescent indicia, make use of the authentication system and methods.