While coins are easy for automatise systems to serve because of their differing sizes and free weight , bills are a unlike fauna . They became a challenge for the hawk industriousness once rising prices meant that object which plopped out of machine were deserving enough to justify paper money .
One of the original and still - leading manufacturing business of this engineering is MEI , which originatedin the 1970s within Mars Inc. , the confect company that makes M&Ms , Skittles and Twix Bars . ( MEI stands for “ Mars Electronics International . ” ) The oldest machinestook advantageof the magnetized ink used in paper up-to-dateness . The machines contained a magnetic head that could “ understand ” the specific quality of each denomination . ( like technology reads audio cassette tapes . ) Markings , crumples , and pass could strain the magnetic “ signature ” on a flyer , and the head themselves could be befog with debris over time . That ’s why vending auto so frequently spat back your dollar sign and leave poor souls soda - less in the ' eighty .
Nowadays , many vend auto are made withphotocells or camerasthat can be program to realize the optic mark of various measure . Lights illuminate the bill , allowing the flyspeck television camera to scrutinise for these sometimes subtle mark . This is advantageous because , should the Treasury issue a new design , the manufacturer of the machine can programme it into its computer . They are also less susceptible to con artists — counterfeit with charismatic ink that would n’t fool a computer or human could well pass through the magnetic head of an erstwhile vending motorcar .
Many top - of - the - line bill validators used in businesses like Las Vegas casinos use several techniques . They can notice magnetised corpuscle , the unique paper and gamey - iron ink used by the U.S. Treasury Department , and even unique shadow that appear on each part of a broadsheet when perch from behind .
Since they ’re not a Brobdingnagian target for big - money fraudsters , your local launderette or fall apart elbow room machine in all likelihood swear on garish , simple applied science to get the business done . It ’s just one reason whya startupthat sent quarters in the mail every two - workweek laundry round never really choose off — thanks to automate neb reader , making variety at the laundromat is leisurely enough already .
