| 摘要 |
In order to recognise the value of a coin, the coin (1) is made to fall onto an anvil (2) so as to set it in resonance. With the aid of a microphone (3), a certain number of frequencies are detected, frequencies comprising the spectrum of the sound wave emitted by the coin and characteristic of the coin and, after filtering (5), the detected spectrum is compared, with the aid of a logic circuit (6), with a table of spectra which are representative of various values of coins. Thus an entirely electronic device is obtained, which may be directly linked to an electronic information-processing apparatus. Its mass-production is simple and inexpensive; it may be used in a coin-operated apparatus. <IMAGE>
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