Document having concealed electrically conductive authenticating layer

• US 4,579,371 A
• Filed: 12/27/1983
• Issued: 04/01/1986
• Est. Priority Date: 12/27/1983
• Status: Expired due to Fees

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Fischer, Richard M. Jr., Long, William H.
• Primary Examiner(s): Bell, Paul A.
• Assistant Examiner(s): Heyrana, Paul M.
• Application Number:
  US06/565,453
• Time in Patent Office: 826 Days
• Field of Search: 283/70, 283/82, 283/83, 283/94, 283/72, 427/7
• US Class Current: 283/83
• CPC Class Codes: B42D 2033/04 Transparent material
• CPC Class Codes: B42D 2033/20 Coloured material; Pigments or inks
• CPC Class Codes: B42D 2033/32 Other material
• CPC Class Codes: B42D 2035/06 Picture of the user
• CPC Class Codes: B42D 2035/08 Alphanumerical data
• CPC Class Codes: B42D 25/00 Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof printing processes to produce identification or security features B41M3/14
• CPC Class Codes: B42D 25/21 for multiple purposes
• CPC Class Codes: B42D 25/309 Photographs
• CPC Class Codes: G06K 19/067 Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
• CPC Class Codes: G07F 7/086 by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10

Abstract

A standardized document such as a credit card or drivers license contains an electrically conductive authenticating layer which is not visually discernible and has an electrical resistivity of less than 50 megohms per square. The presence of the authenticating layer may be verified by a proximity switch that can be built into mechanisms normally used in processing the document.

Claims

1. A standardized document including an authenticating layer of electrically conductive material comprising a mixture of ionizable salt and ionizing agent uniformly dispersed in an organic binder, which layer extends over an area of at least 4 mm square and has an electrical resistivity of less than 50 megohms per square, the document being substantially visually indistinguishable from a document which would be identical except for omission of said layer, and a transparent protective plastic film covering said authenticating layer.

2. Document as defined in claim 1 wherein the authenticating layer has an electrical resistivity of less than 500,000 ohms per square.

3. Document as defined in claim 1 wherein the authenticating layer is coextensive with the document.

4. Document as defined in claim 3 wherein the authenticating layer covers the face of the document.

5. Document as defined in claim 1 wherein the electrically conductive material and organic binder are colorless.

6. Document as defined in claim 1 wherein the conductive material comprises semiconductive salt.

7. Document as defined in claim 6 wherein the semiconductive salt is colored and a surface of the document which bears said authenticating layer has the same color.