| 摘要 |
A secure contest card which is not susceptible to compromise by both simple and sophisticated techniques comprises printed indicia disposed on the upper surface of card stock material, a patterned intermediate layer disposed over the printed indicia and an opaque removable mask disposed over the intermediate layer and over the printed indicia. In a second embodiment of the invention a patterned background layer is disposed between the card stock and the printed indicia and the patterned intermediate layer is eliminated. In a third and preferred embodiment, the patterned background layer and the patterned intermediate layer are both employed. It has been found that the pattern in the background and intermediate layers creates an irregular relationship with the indicia and defeats certain new techniques for compromise of apparently secure contest cards.
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