COIN RECOGNITION

摘要

Coins are recognised by monitoring the decay of an eddy current induced therein. In a preferred embodiment a coin is placed in inductive relationship with a coil 10 and a pulse of 1 to 100 mu s is applied.The decay of the eddy current induces a signal in the coil and instantaneous values are recorded, e.g. at 10 mu s, 25 mu s and 45 mu s after the pulse. The coin is recognised by comparing these values with stored values characteristic of various denominations. The characteristic values are conveniently obtained by operating in a learn mode in which coins of known denominations are measured and the maximum and minimum values are stored as the characteristic values.