Optically variable security devices

Abstract

A security article includes a light transmissive substrate having a first surface and an opposing second surface, with the first surface having an optical interference pattern such as a holographic image pattern or an optical diffraction pattern thereon. A color shifting optical coating is formed on the substrate such as on the interference pattern or on the opposing second surface of the substrate, with the optical coating providing an observable color shift as the angle of incident light or viewing angle changes. Various processes can be utilized to form the security article, such as vacuum coating processes, lamination, laser scribing, and laser imaging. The security article can be affixed to a variety of objects through various attachment mechanisms, such as pressure sensitive adhesives or hot stamping processes, to provide for enhanced security measures such as anticounterfeiting.

Description

[0001] This is a divisional application of U.S. application Ser. No. 09 / 489,250, filed Jan. 21, 2000 and entitled "Optically Variable Security Devices," which is incorporated herein by reference, and to which priority is claimed.[0002] This application is related to U.S. application Ser. No. 09 / 351,102, filed Jul. 8, 1999, and entitled "Diffractive Surfaces with Color Shifting Backgrounds."[0003] This application is related to U.S. application Ser. No. 10 / 688,357, filed Oct. 17, 2003, and entitled "Security Articles having Diffractive Surfaces and Color Shifting Backgrounds."[0004] 1. The Field of the Invention[0005] The present invention is related generally to thin film optical coatings for use in producing security articles. More specifically, the present invention is related to the production of diffractive surfaces such as holograms or gratings having color shifting or optically variable backgrounds which can be used as security articles in a variety of applications.[0006] 2. T...

AI Technical Summary

Benefits of technology

[0018] It is a primary object of the invention to provide a security article having color shifting properties which increases the difficulty of counterfeiting in a variety of applications.

Problems solved by technology

Various ways to counteract these methods have been explored but none of the countermeasures, taken alone, has been found to be an effective deterrent.

A further problem with security holograms is that it is difficult for most people to identify and recollect the respective images produced by such holograms for verification purposes.

The ability of the average person to authenticate a security hologram conclusively is compromised by the complexity of its features and by confusion with decorative diffractive packaging.

Thus, most people tend to confirm the presence of such a security device rather than verifying the actual image.

Unfortunately, this added complexity does not confer added security because this complex imagery is hard to communicate and recollection of such imagery is difficult, if not impossible, to remember.

Images