Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Inadvertent or fraudulent copying of a confidential "don't copy" document can be detected by coating the document with a dye that reacts with the intense imaging light of copier. Most copying machines on the market have a halogen lamp as the source of light. Others use a fluorescent lamp or flush-type light source. To project an image from the document, those lights illuminate the document at a high level of intensity that is much higher than room light. Dyes reactive to intense light are coated or impregnated on all or port of document surface in one of the following processes: 1) A dye dispersed in a binder is activated by the light energy and initiates coloring. 2) A dye dispersed in a binder with a photochemical reaction agent is activated by the agent that transfers light energy to the dye and initiates coloring.