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Identification card with a visible authenticity feature

  • US 4,894,110 A
  • Filed: 06/29/1988
  • Issued: 01/16/1990
  • Est. Priority Date: 10/15/1985
  • Status: Expired due to Term
First Claim
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1. A method for manufacturing an identification card containing a plurality of synthetic layers in which information is provided by means of a laser beam, said information being visible as changes in the optical properties of the synthetic layers due to irreversible changes in the material caused by the laser beam, characterized in thatthe individual layers are joined together to form a card compound, at least a first and a second synthetic layer having transparent areas which overlap,the first layer and the second layer have a property of changing visibly when exposed to the laser beam, this change being effected only as of certain intensity values, a particular intensity value required herefor being lower for the first layer than for the second layer,the card compound is oriented toward the laser in such a way that the second layer comes to lie on a side facing the laser,at least parts of the information are provided with an intensity which causes visible changes of material to occur simultaneously in the first and second layers, andfirst and second pieces of information are provided in such a way as to be visible overlapping at a first viewing angle and singly at a second viewing angle, the appearance of the pieces of information changing in accordance with the viewing angle.

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