No public transport ticketing system has a lot to promote use of car, bus companies have given fake coins causing huge economic losses, these problems also exist in the vending machines, pay phones, game consoles, bank coin sorting machine.Real-time, accurate, and automate the identification of coins and currency counterfeit Kam, is technically achievable.The characteristics of a coin material, weight, color, thickness, diameter and surface patterns, etc., which can be used to identify coins.In order to achieve both coins and currency counterfeit identification Kam, the main use of coins in the material characteristics.Eddy current sensor is used most in the form of access to the sensor coil as the inductor three-capacitor oscillator circuit, the application of resonant oscillation frequency measurement circuit.Every dollar coin has a characteristic oscillation frequency, will they advance into the single chip EPROM.When the coin through the sensor, the oscillation frequency of circuit changes, the measured oscillation frequency and characteristics of oscillation frequency compared to determine the authenticity of coins and currency.But the oscillation circuit is affected by temperature and other environmental factors influenced this aspect of baseline characteristics reduced the oscillation frequency stored adaptability, it also makes the measurement of the oscillation frequency fl


公交系統(tǒng)的無人售票車已經(jīng)大量推廣使用，假硬幣已經(jīng)給公交企業(yè)造成巨大的經(jīng)濟(jì)損失，這些問題也同樣存在于自動(dòng)售貨機(jī)、投幣電話、游戲機(jī)、銀行硬幣分檢機(jī)中。實(shí)時(shí)、準(zhǔn)確、自動(dòng)地實(shí)現(xiàn)硬幣鑒偽與幣值識別，在技術(shù)上是可以實(shí)現(xiàn)的。硬幣的特征有材質(zhì)、重量、顏色、厚度、直徑和表面圖案等，它們都可以用于硬幣鑒別。為了同時(shí)實(shí)現(xiàn)硬幣鑒偽與幣值識別，主要利用硬幣的材質(zhì)特征。電渦流傳感器是目前采用最多的形式，把傳感器線圈作為電感接入電容三點(diǎn)式振蕩電路中，應(yīng)用諧振法測量電路的振蕩頻率。每一種幣值的硬幣都有一特征振蕩頻率， 將它們預(yù)先存入單片機(jī)的EPROM 中。當(dāng)硬幣經(jīng)過傳感器時(shí)，振蕩電路的頻率變化，將測得的振蕩頻率與特征振蕩頻率比較，以判別硬幣的真?zhèn)魏蛶胖?。但振蕩電路受溫度等環(huán)境因素的影響較大，這一方面降低了預(yù)存的基準(zhǔn)特征振蕩頻率的適應(yīng)性，另一方面也使得實(shí)測的振蕩頻率波動(dòng)范圍變大。這樣，溫度等環(huán)境因素將導(dǎo)致系統(tǒng)的誤判率加大，即使進(jìn)行復(fù)雜的溫度補(bǔ)償，效果也不太理想。本文研制了一種基于差動(dòng)變壓器的硬幣鑒偽及幣值識別系統(tǒng)，其主要的技術(shù)要求：有較強(qiáng)的鑒別偽幣的能力； 能正確區(qū)分目前國內(nèi)流通的6 種面值的硬幣，并具有一定的柔性，以便適應(yīng)新的幣種；鑒幣時(shí)間小于每次500ms；受溫度等環(huán)境因素影響極??；結(jié)構(gòu)簡單緊湊，加工工藝性好；價(jià)格便宜。