| 摘要 |
In a currency acceptor, a transport having a reversible drive conveys a bill to be tested along a path of travel past a first photoelectric detector, a transducer head at a test station for sensing the physical properties of the bill, and then a second photoelectric detector. If the grid areas on opposite sides of the portrait on the bill have physical properties indicative of validity, testing circuitry responsive to the head produces an accept signal as each grid area passes the head. To be deemed valid, the first grid area must cause the production of an accept signal, the leading and trailing edges of the bill must be concurrently detected by the two photoelectric detectors as the portrait passes the head (determines that the bill is not too short), the second grid area must cause the production of a second accept signal by the time the bill reaches a predetermined position along the path, and thereafter the first photoelectric detector must not detect the bill or another, following bill until such time that the bill completely passes the second photoelectric detector and is accepted. If an invalid condition is encountered, the transport drive is reversed and the bill or counterfeit material is returned to the depositor and thereby rejected.
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