Security document and method using invisible coded markings
First Claim
1. A composition comprising a substrate and a compound imprinted on a surface of said substrate, said compound when exposed to an excitation radiation produces a fluorescence having a wavelength greater than about 650 nm, and wherein said compound is separated from said excitation radiation by a layer of material that substantially reflects or absorbs visible and ultraviolet radiation.
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Accused Products
Abstract
An invisible indicia or encoded information is imprinted on a substrate using a compound which produces a fluorescence at a wavelength greater than about 650 nm when exposed to near infrared radiation. The information covered by a layer of material that reflects or absorbs a substantial amount of the visible and UV radiation illuminating its surface.
182 Citations
23 Claims
- 1. A composition comprising a substrate and a compound imprinted on a surface of said substrate, said compound when exposed to an excitation radiation produces a fluorescence having a wavelength greater than about 650 nm, and wherein said compound is separated from said excitation radiation by a layer of material that substantially reflects or absorbs visible and ultraviolet radiation.
- 13. A security document comprising a substrate having invisible imprinted indicia or encoded information thereon, said invisible imprinted indicia or encoded information comprising a compound that when exposed to an excitation radiation produces a fluorescence having a wavelength greater than about 650 nm, and wherein said compound is separated from said excitation radiation by a layer of material that substantially reflects or absorbs visible and ultraviolet radiation.
- 16. A method for marking encoded information on a substrate, said method comprising applying a mark on the substrate using a composition having a fluorophoric compound which fluoresces at a wavelength greater than about 650 nm and covering said marking composition with a layer of material which substantially absorbs or reflects visible and ultraviolet radiation.
Specification