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Marking and authenticating documents with liquid crystal materials

  • US 4,514,085 A
  • Filed: 06/28/1982
  • Issued: 04/30/1985
  • Est. Priority Date: 06/28/1982
  • Status: Expired due to Fees
First Claim
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1. A method of repeatably authenticating documents comprising the steps of:

  • (1) applying a liquid crystal material to the document, which material exhibits a predetermined response to an electrical or magnetic stimulus, and(2) examining the document for detectable characteristics of the predetermined response of the liquid crystal material when said stimulus is applied.

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