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Counting the number of banknotes in a stack using the optical technology

Discussion in 'Electronic Basics' started by Aks, Mar 31, 2007.

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  1. Aks

    Aks Guest

    Hi People.

    I am looking at a particular application. I want to build a currency
    counter. The device will be based on optical technology. What I want
    to do is, "look" at the side of the stack of banknotes and from there,
    read the number of notes present in the stack.

    There are two possible approached that come to my mind :

    1.) The CD-ROM Approach

    Here, the light is made to incident on the "side" of the stack and
    whatever light is reflected back, is read by a device. Now, the number
    of "gaps" in the light gives us the number of notes.
    The upside of using this approach will be less complexity in the
    The downside will be , this approach will involve moving mechanical
    parts. (In the form of a light source that 'scans' the entire width of
    the 'side' of the stack)
    I've found a patent for this approach. Here's the link.

    Here is a list of patents related to this one^20 OR 4694474

    And here is the US patent Number 4694474,4694474&stemming=on

    To read the full texts of these patents, u need to make and account on Its free.

    2.) The image-processing approach
    An image of the 'side' of the stack is taken by a CCD or a CMOS
    camera. The image is then passed on to an image processing unit which
    then processes the image. There can be seen visible distinct 'lines',
    horizontal lines in the image. Each line representing one note. If we
    can read the number of such lines, we can build such a device.
    Now, I've got a patent for this as well. And en extremely detailed
    one, describing, in detail, the complete hardware, software and the
    diagrams of the project. Here it is.

    US Patent Number 5534690,5534690&stemming=on

    But being from computer science background, I am unable to understand
    this completely. Can someone help me ?
    I am ready to pay, if someone can make that thing for me. I am based
    in India.

  2. john jardine

    john jardine Guest

    Offhand I'd think you've a cat-in-hell's-chance of counting to any better
    than say 60% accuracy. Look at any slab of cut paper and its impossible to
    differentiate the individual items. Fancy cameras and software will not
    improve on this.
    For Currency, the accountants need 100% accuracy, 99.9% is unacceptable.
  3. Bob Masta

    Bob Masta Guest


    Why are you limiting this to optical methods? The method you
    propose can't read denominations anway, so why not just
    weigh the stack on a sensitive scale?

    Best regards,

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    Scope, Spectrum, Spectrogram, Signal Generator
    Science with your sound card!
  4. Aks

    Aks Guest

    I am not interested in denominations. All I want to know is, how many
    notes are there in a stack of notes. The size of the stack is of the
    order of 100 notes. I want this device to be handheld and mobile. It
    has to be VERY light. And this seems possible only if I use the
    optical technology.

  5. Aks

    Aks Guest

    On the contrary, I think using optical technology will greatly enhance
    the accuracy of the device.
    The pits on the surface of a CD-ROM disk are much more fine than the
    gaps between two adjacent notes, or tha width of any note. For the
    record, the pits on a CD are 0.5-1 micrometer in size. Whereas a
    bundle of 100 new notes (worst case) is around 7-8 mm - giving the
    average thickness of one note as 7/100 = 0.07mm or 70 micrometer.
    Now, if the light can read and distinguish something of the order of
    1micrometer, I say, it can DEFINITELY read something of the order of
    70 micrometer.
    I tried taking a picture of a side of the stack of 100 notes. And even
    there, I could see the notes distinctively. If you have a look at the
    patents links that I provided, you will find the drawings of this.
    After magnification, it becomes very clear. A good image processing
    program, must then be able to 'count' the number of notes.

  6. john jardine

    john jardine Guest

    In the interests of mindless curiosity I looked at a CD with a microscpe and
    320X magnification. Each pit was clear and well defined, perfectly visible
    as a clean, unwavering, string of high contrast white dots with black
    seperators. Could even have read the binary straight off. Then looked at the
    edge of a block of 20 sheets of paper (X50, X10 mag' under various light
    conditions). Yes, the sheets were individually visible.
    But, I found the sheet to sheet colour and edge contrast quite poor and
    required the light source to be fiddled with for best results. Also required
    some shuffling about of the paper to clarify edges where the fibres had
    splayed and spoiled the seperation line. Can well written software tease out
    more detail than an eye/brain neural net?.
    Curiosity satisfied, I'll increase the cat-in-hell's chances to 65% :)
  7. jasen

    jasen Guest

    seems kind of tricky..

    have you condisered mechanical means?

    run a phonograph needle up the stack and count pulses.

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