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Optical Mice Used To Detect Counterfeit Coins 123

JimXugle writes "El Mundo reports that Spanish researchers at The University of Lleida have used a modified optical mouse to detect counterfeit €2 coins (Original article, in Spanish) with a success rate comparable to that of an expert trained to do so. Details are to be published freely in the journal Sensors."
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Optical Mice Used To Detect Counterfeit Coins

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  • by shankarunni ( 1002529 ) on Monday November 16, 2009 @06:18PM (#30122708)

    Vending machines rely on mechanical factors, mostly: Weight, size, metallic composition (measured by conductivity characteristics).

    This one seems to focus on the graphics on the faces. It's complementary.

  • Fun fact #65 (Score:4, Informative)

    by dvh.tosomja ( 1235032 ) on Monday November 16, 2009 @06:42PM (#30122998)

    Did you know that there are more than 260 different euro coins from 19 countries to present day!

  • by BKX ( 5066 ) on Monday November 16, 2009 @06:48PM (#30123080) Journal

    Vending machine detectors are usually just magnets (at least in the US). Very few countries make their coins with enough iron, nickel, or cobalt to be magnetic, so a magnet can pick out most slugs (the usual form of counterfeiting used on vending machines). I know; I own vending machines.

    Also, it's OT, but your sig annoys the crap out of me. I use whom correctly all the time, "intensive purposes" is retarded. Begging the question, though, seems to have actually changed meanings over the years, so, being a descriptivist, I'll give you that one.

  • by Drishmung ( 458368 ) on Monday November 16, 2009 @07:19PM (#30123484)
    Are they just magnets?

    My understanding was that the coin falls into a balanced cradle that measures the diameter and weight. If it's the wrong size it is rejected (and can fall through to another cradle that tests for a different value coin---and so on). If it is the right size but the wrong weight the cradle tips too far or not far enough and deposits it in the reject slot.

    If it's the right size and weight then the coin drops between two magnets onto a little anvil. If the metallic composition is right the coin will slow just enough passing through the magnets to hit the anvil at the right place and speed to bounce into the accept slot. Anything else and it misses.

    The end result is a very quick, accurate but cheap analysis of the coin's weight, size and metallic composition.

    I know that's the way it used to work. Have they dumbed down the machines recently?

  • by xaxa ( 988988 ) on Monday November 16, 2009 @08:04PM (#30123946)

    I don't know about €2 coins, but loads of £1 coins are counterfeit -- perhaps 5% []. The €2 (and 1) are bi-metallic though, so presumably harder to fake.

    Under UK law (as that page explains), once you know a coin is counterfeit it's illegal to give it to anyone (except the police) or to keep it. Daft, but it means it's in my interest not to identify counterfeits. (Unless, possibly, I checked every time I was given change. But that's not realistic.)

  • by santathehutt ( 1172249 ) on Monday November 16, 2009 @09:01PM (#30124494)
    Back in the 90's I worked for a company that built coin changers and acceptors. Even back then they were using a more advanced method than the one you describe. The acceptor was actually the part that determined what type of coin was inserted and would reject it if it was a slug. The acceptor worked on the same principle as a metal detector. Since coins are made up of a unique mix of metals the acceptors could be "tuned" to accept a certain coin by dropping versions of that kind from different years and differing conditions. This would create a range of values for each coin. When a coin is dropped into the acceptor it gets a reading of the coin. If it is in the range of one of the coins the acceptor is programmed to accept then the coin is routed to the proper coin tube or the cash box if the tube is full. Otherwise it will be rejected as a slug. The acceptor is actually plugged into the top of the changer as a complete unit. For what it's worth I did see an acceptor there one day that worked similar to the way you described, but I believe it was from the 70's or early 80's.

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