| 摘要 |
<p>A document processing apparatus (10) incorporates a counterfeit detection system for identifying counterfeit suspect documents (22) on the basis of the magnetic characteristics of the documents (22). Each document (22) is transported within the vicinity of a magnet read head (86), which produces an electronic signal (210) in response thereto. The signal (210) from read head (86) is conditioned by a conditioning circuit (110) to be compatible with an analog-to-digital converter (304). The conditioning circuit (110) includes one or more amplifiers (130), a filter (140), a rectifier (160) and an integrator (180). The conditioned signal (220) from the integrator (180) is provided to the analog-to-digital converter (304) and is optionally limited to a compatible voltage level. As each document (22) is detected, a plurality of sampled values are obtained by the analog-to-digital converter (304). The sampled values are accumulated to produce one or more cumulative values (242, 274, 292, 404, 412) representative of the document (22). The cumulative values are compared with one or more predetermined reference values (263, 264, 276, 280, 282, 288, 402, 406, 410, 414) associated with a genuine document (22) in order to determine whether the detected document (22) is a counterfeit suspect document (22).</p> |
