SECURITY DOCUMENTS WITH VISIBLE AND INVISIBLE MARKINGS

摘要

A difficult-to-counterfeit document comprising, together with data printed in visible form, invisible indicia that are personalized in nature, and which cannot be seen without the cooperation of an external factor. The invisible indicia are printed with a luminescent ink or toner, and becomes visible by the application of irradiaton, such as UV light. The luminescent ink or toner may comprise fluorescent materials. The same type of document may bear different invisible indicia for different bearers or documents, and may be printed by conventional digital printing methods.