Vouchers and methods for providing vouchers configured to assist in distinguishing unauthorized duplicate or counterfeit vouchers are disclosed herein. In one embodiment, a voucher can include a substrate, a first indicia on the substrate, and a thermally responsive second indicia on the substrate. At...http://www.google.fr/patents/US6644696?utm_source=gb-gplus-shareBrevet US6644696 - Coin-discriminator voucher anti-counterfeiting method and apparatus
Coin-discriminator voucher anti-counterfeiting method and apparatus
