Design And Implementation Of The Coin Feature Detection Device

Along with the increasing demand of efficiency and convenience in human society,coin circulation automation technology get widely used in daily life,such as: Gaming terminal,Coin exchange machine,Ticket vending machine,Vending machine,etc.However,using counterfeit coins and game coins in place of real money happen occasionally.Therefore,it is a necessary technique install Coin discriminator in Coins exchange,Coins circulation automatic equipment.Therefore,to design a coin counterfeit detection device which can detect the characteristics of coins have important theoretical and applied value.Altera`s FPGA is a high speed,programmable digital hardware processor.This article attempts to use it in the digital programming control of the coin feature detection device and achieved better results.Based on the deep research on coin characteristic detection theory,this article describe the principle of eddy current generation firstly,and then analyzed the working mode of “low frequency penetrating eddy current sensor” and “high frequency reflective eddy current sensor” in details based on this principle,then analyzed the there coin characteristic detecton method and selected two of them;According to the performance index of the coin characteristic detection device,the key component parameters are determined,the hardware schematic is designed.Regarding the software control system,this article specified the software structure and function module,then finished the design of main process,and studied the design theory of using DDS control and FFT to detect the coin’s characteristic.The eddy current sensor is the key components for coin characteristic recognization,and the signal conditioning circuit can enlarge and convert the analog signal to digital,then the digital signal will sent to core control circuit for parameter calculatation.Finally,according to the scheme of this article,completed the development of coin characteristic detection device,and finished the joint debugging.The testing result of acceptance and rejection rate for real coin & counterfeit coin & game coin proved that this coin characteristic detection devi ce can recognize the coin characteristic by detecting the coin material & thickness & plating layer & pattern,so the device can recognize real coin and counterfeit coin.Compare to other detection device,this device have better perfromance in counterfeit coin recognization and detection efficiency.