| 摘要 |
A method and apparatus for validating printed matter, particularly cheques or documents, is disclosed. This is achieved by comparing a visible sequence of digits, marks or a code 106 printed on a substrate 100 with a hidden sequence of digits, marks or a code 102 also printed on the substrate 100 which becomes visible when the substrate 100 is viewed with non-visible radiation, such as infrared light. The hidden sequence of digits 102 may be formed by printing the digits, marks or code as a visible first printed portion that absorbs both visible and invisible radiation then printing a second printed portion 104 visible digits, marks or code over the hidden code 102 at least partially obscuring it. The second printed portion 104 should absorb visible radiation but should not absorb non-visible radiation. When exposed to non-visible radiation, the hidden digits, marks or code 102 can be discerned and compared to the visible digits, marks or code 106 to validate the printed matter. The colour of the inks used to print the hidden sequence 102 and the cover layer 104 is preferably the same. In another embodiment the visible digits, marks or code 106 could also be invisible, perhaps being discernable under ultraviolet radiation. The printed matter may be a document or a cheque. |
