| 摘要 |
A bill transport of a currency acceptor conveys a bill inserted thereinto along a path of travel having a sharp initial bend followed by a rectilinear stretch defined by an elongated, narrow channel. The bend is formed by rollers at the inside of the bend opposed by endless belts presenting the outside of the bend. A validity test station is located intermediate the ends of the cannel, and the bill is held flat as it is advanced along the channel by two rows of opposed pairs of rollers projecting into the channel and receiving the bill adjacent its longitudinal edges. A constant speed transport drive is provided by a direct current motor governed by a centrifugal chopper. Failure to maintain proper operating speed due to jamming or the like results in the application of an unchopped voltage to the motor, causing voltage to build up across a capacitor to a level which fires a programmable unijunction transistor that, through associated switching circuits, reverses the polarity at the motor input connections to reverse the drive and return the bill to the insert opening. Such switching circuits are also operated by the validity tester to return a bill found to be invalid.
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