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Low visibility watermark using time decay fluorescence

  • US 20050013463A1
  • Filed: 04/05/2004
  • Published: 01/20/2005
  • Est. Priority Date: 04/19/2000
  • Status: Active Grant
First Claim
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1. A copy detection method comprising:

  • receiving optical scan data associated with a printed object, wherein the printed object comprises a first-machine readable component printed thereon with first ink comprising a first emission decay time, and a second component printed thereon with second ink comprising a second emission decay time; and

    machine-reading the first component when emissions of the second ink decay to a first predetermined level.

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