| 摘要 |
<p>PURPOSE: To identify a coil correctly through a simple apparatus without requiring a precise allowance and thereby with no trouble by measuring reduction in a different effect caused by a coil or other article passing through a field. CONSTITUTION: A comparator 23 combined with an amplifier/driver circuit 22 delivers an output to a transmitter coil 25 having a predetermined peak value. A coil 25 and a receiver coil 26 are formed by winding a wire around a rectangular plexiglass base and has width of about 5/8 and length of about 11/2. Output from the coil 26 is fed to a differential amplifier 27 and a conditioner 28 where a signal 29 from the circuit 22 leaves only the signals produced from respective coin passages and ineffective quadrature are summed. Plus mean value of the signal is converted through a circuit 30 into a DC current and delivered to a minus peak detector 31. A conditioned DC signal is subjected to A/D conversion 32 and fed to a microprocessor 33 where it is compared with a prestored type of coin and the coil is identified.</p> |
