| 摘要 |
A security feature (1) that is used with a substrate (2). The security feature includes a plurality of fluorescent micro-particles (1A) that form a background component of the security feature and a plurality of fluorescent discrete particles (1B) that form a foreground component of the security feature. The discrete particles are larger in size than the micro-particles and are optically distinguishable from the micro-particles under at least one illumination condition. In the preferred embodiment the security feature is applied as a coating to the substrate, and the security feature further includes a coating binder (1C) in which the micro-particles and the discrete particles are contained. The coating binder can be made of, for example, at least one of an ink base, an adhesive, an epoxy, a varnish, a polymer solution, or a dry material having binding properties. The coating binder may be substantially transparent or substantially opaque. The discrete particles are optically distinguishable from the micro-particles under long wavelength ultraviolet light and/or under short wavelength ultraviolet light. Under no or low magnification conditions the security feature exhibits a generally uniform color to the naked eye, while in one embodiment under higher magnification conditions the discrete particles exhibit a first color while the micro-particles of the background component exhibit a second color, while in another embodiment the discrete particles exhibit a first color while the micro-particles of the background component exhibit a lack of color, while in a further embodiment the micro-particles of the background component exhibit a first color while the discrete particles exhibit a lack of color. The security feature exhibits a fluorescent signature having attributes given by at least one of particle count per unit area, specific particle size range which may or may not differ by fluorescent color, relative intensities of measured spectral emission peaks due to foreground component particle fluorescence versus background component micro-particle fluorescence and specific emission wavelength values of measured spectral emission peaks due to foreground component particle fluorescence versus background component micro-particle fluorescence.
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