Design And Application Of High Accuracy Coins Detecting Instrument

The modern human society pursues convenient, the common usage of coins'automatic circulation technology is a typical illustration. Such as automatic vendors, pay phones, arcade games and self-service ticketing buses are all the typical application examples. However, at the situation that people's social moral are not universally advanced, the facts that using the fake coins as the real ones happen frequently. Hence, it becomes a necessary technology method to install coins detecting instrument in the coins automatic circulation facility. There are coins detecting instruments in the market at present already. Because of the technology disadvantages of hardware structures or the software arithmetic, it is common phenomenon that the costs are too high and the accuracies are too low.This paper will detailed expatiate a design and realization technology of low-cost and high-accuracy coin detecting instrument. This instrument has the function of learning. It can store the material characteristic of the real coins in the EEPROM memory through the learning of all kinds of coins in the market, and using this as the standard to judge the coins are real or fake. Otherwise, this system has the function that upgrade online. If there are new kinds of real coins in the market, we can just start the learning function and store the new coins'material characteristics in the EEPROM memory. Hence, add the function to detect the new kind of coins. This coins detecting instrument including electromagnetic sensor, signal adjusting circuit, kernel control chip and valve switch circuit. The electromagnetic sensor generates the eddy current effect,it is the key sensor part to realize the function of detecting the coins. The signal adjusting circuit transforms analog signals of eddy current effect into digital signals. The digital signals are processed by kernel control chip real time. The valve switch circuit is used to control the relay, determine to receive or reject the coins. This paper expatiate several improvement methods on increasing the accuracy. Through double-frequency detecting method on the hardware aspect, and speed-weighted arithmetic on the software aspect, making the accuracy of detecting the fake coin above 98.3%.