| 摘要 |
<p>A coin validator comprises a microprocessor (4) which is periodically activated to check the output of an arrival sensing circuit (6) to determine whether a coin has arrived. The circuit (6) includes a printed circuit inductance (10) and produces an output signal the frequency of which alters when a coin arrives and is used to indicate coin diameter. The circuit (6) is designed so that output amplitude variations are minimised. Arrival of a coin causes powering-up of a material/thikness sensing circuit (8). In one embodiment both the frequency and amplitude of the output signal from this circuit are used to determine the denomination of the inserted coin. The amplitude profile may be used to determine when to measure frequency, and which of a plurality of successive amplitude measurements are to be combined to provide an averaged amplitude value. A counter (24) is used for frequency and amplitude measurement, and for periodically activating the microprocessor (4). Coins are rejected if they travel too quickly through a testing station of the validator. The validator is operable in a test mode to indicate, in response to an inserted coin, how the sensing circuits (6, 8) should be adjusted to provide optimum operation.</p> |
