| abstract |
Voidable articles are made with an identification code and a radiant energy responsive material coated over said code. The material is invisible and remains unactivated in ambient light but obscures the identification code upon being exposed to radiant energies such as heat or light from within a particular wavelength range. Printing can be accomplished by imaging light onto a substrate coated with photosensitive material including an infrared absorbing dye. A cancellation device for voiding documents of the present invention is made with a scanner, a comparator and a radiant energy source for exposing the document to activate the energy responsive material on the document. |