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

• Current Assignee: GAO Gesellschaft Fur Automation und Organisation mbH
• Original Assignee: GAO Gesellschaft Fur Automation und Organisation mbH
• Inventors: Becker, Wolfgang, Herget, Werner, Lass, Joseph, Lob, Erwin, Merkle, Hansjurgen
• Primary Examiner(s): Ball, Michael W.
• Assistant Examiner(s): AFTERGUT, JEFFRY H
• Application Number:
  US07/213,253
• Time in Patent Office: 566 Days
• Field of Search: 430/10, 430/11, 430/13, 430/14, 430/15, 430/18, 430/945, 283/85, 283/86, 283/94, 283/91, 283/72, 283/74, 283/75, 156/272.8, 156/277, 156/299, 428/916, 219/121.6, 219/121.61, 219/121.85
• US Class Current: 156/272.8
• CPC Class Codes: B41M 3/14 Security printing securities B42D25/29
• CPC Class Codes: B41M 5/267 Marking of plastic artifacts, e.g. with laser
• CPC Class Codes: B42D 25/41 using electromagnetic radiation B42D25/435 takes precedence
• CPC Class Codes: G06K 19/06046 Constructional details
• CPC Class Codes: G06K 19/14 the marking being sensed by radiation
• CPC Class Codes: Y10S 283/904 Credit card
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10S 428/916 Fraud or tamper detecting
• CPC Class Codes: Y10T 156/1092 All laminae planar and face to face
• CPC Class Codes: Y10T 428/24868 Translucent outer layer
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

Information is provided in a multilayer identification card by means of a laser beam. This information is recorded by irreversibly changing (blackening) transparent synthetic material. Synthetic materials which blacked at different intensity values are used for the individual card layers. By controlling the laser beam intensity, information can thus be recorded only in one layer or else simultaneously in several layers. If the layer arrangement, layer materials and recording parameters (intensity, writing width, etc.) are selected appropriately, images can be produced which change their appearance when the viewing angle is changed. The various visual effects which can thereby be obtained serve to distinguish the authenticity of the identification card.

Claims

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 that

the 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, and

first 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.

2. The method according to claim 1, characterized in that a writing width (d) with which the information is recorded is smaller than a sum (D) of the layer thicknesses of the first and second layers plus the thickness of further layers, if any, embedded between these layers.

3. The method according to claim 2, characterized in that depth of focus of the focussed laser beam is considerably greater than a distance between the first and second layers, and in that the card compound is located within the depth of focus on a plane of focus of the laser beam.

4. The method according to claim 2, characterized in that the writing width (d) is smaller than the sum (D) by a factor of two.

5. The method according to claim 1, characterized in that part of the information is inscribed with an intensity lower than a necessary intensity value of the second layer, so that this part of the information is only provided in the first layer.

6. The method according to claim 1, characterized in that recording of information in the second layer is interrupted during a recording process by selectively reducing the intensity.

7. The method according to claim 1, characterized in that a third layer is provided between the first and second transparent layers, said third layer also having a transparent window at least in the overlapping transparent areas of the first and second layers.

8. The method according to claim 7, characterized in that a synthetic material is selected for the third layer whose necessary intensity value for changing the synthetic material of the third layer is between necessary intensity values of the first and second layers, and in that changes are effected in all layers by appropriately selecting the intensity.

9. The method according to claim 7, characterized in that a synthetic material is selected for the third layer whose necessary intensity value for changing the synthetic material of the third layer is higher than necessary intensity values of the first and second layers, the necessary intensity value of the third layer being set such that optical changes are effected only in the first and second layers and pieces of information recorded in this way are spatially separated from each other by a transparent space.

10. The method according to claim 7, characterized in that a synthetic material of the third layer is selected for the third layer whose necessary intensity value for changing the synthetic material of the third layer is between necessary values of the first and second layers, and in that changes are limited to layers with lower necessary intensity values.

11. The method according to claim 1, characterized in that recording is performed by a pulse scanning method.

12. The method according to claim 11, characterized in that pulse frequency and scanning speed are selected in such a way that successive pulses overlap.