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7 April 2000 Combining thermochromics and conventional inks to deter document fraud
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The ability to print high-resolution thermochromic indicia, combining conventional inks with sophisticated printing technologies to either camouflage latent messages or create a warning message when copied, is new. (1) For Authentication: Offset thermochromic inks can trap a message that is printed in conventional ink. The conventional ink must match the thermochromic ink in density and color hue in order to perfectly hide at typical office room temperature. This technique is very difficult to manufacture. Even if a fraudster was to obtain the protected ink, the technology is still extremely difficult to replicate. (2) For Copy Protection: Irregular pattern graphics printed in thermochromic ink over a linear Copy/Void message, or dot pattern Copy/Void message, allows for superior protection against replication. The thermochromic pantograph camouflages the Copy/Void message. But, because thermochromic inks are both temperature sensitive and low in color pigment, the Copy/Void message prints through the ink onto the copy. This technology allows for an increase in disparity between the message and the background screen; maximizing protection effectiveness. Documents utilizing ThermoSafe and TouchSafe technologies have been produced in the tens of millions as a fraud deterrent. To our knowledge these security technologies have yet to be compromised.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
George K. Phillips "Combining thermochromics and conventional inks to deter document fraud", Proc. SPIE 3973, Optical Security and Counterfeit Deterrence Techniques III, (7 April 2000);

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