Money validator
First Claim
Patent Images
1. A method of classifying a test article as one of a plurality of acceptable denominations of articles of currency, comprising:
- deriving a plurality of measurement signals from a test article; and
applying an acceptance process to said measurement signals, said acceptance process calculating first, second and third outputs indicating correspondence with first, second and third denominations, wherein for each said test item said acceptance process is performed a plurality of times, differently adjusted to compensate for the effects of measurement drift for at least said first, second and third denominations at each performance, and in that in each performance of said acceptance process, an output corresponding to the denomination for which the acceptance process is adjusted is calculated, and at least two other outputs for two different denominations are also calculated.
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Abstract
A method of classifying a test article as one of a plurality of acceptable denominations of articles of currency, comprising applying a statistical classification process which employs discriminant surfaces derived from previous test articles known to be valid or invalid and is arranged to distinguish therebetween, characterized by applying also an acceptance boundary test which limits the acceptance volume for each denomination so as to exclude forgeries for which the discriminant surfaces were not derived.
36 Citations
28 Claims
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1. A method of classifying a test article as one of a plurality of acceptable denominations of articles of currency, comprising:
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deriving a plurality of measurement signals from a test article; and applying an acceptance process to said measurement signals, said acceptance process calculating first, second and third outputs indicating correspondence with first, second and third denominations, wherein for each said test item said acceptance process is performed a plurality of times, differently adjusted to compensate for the effects of measurement drift for at least said first, second and third denominations at each performance, and in that in each performance of said acceptance process, an output corresponding to the denomination for which the acceptance process is adjusted is calculated, and at least two other outputs for two different denominations are also calculated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of classifying a test article as one of a plurality of acceptable denominations of articles of currency, comprising:
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applying a classification process employing previously derived and stored reference data of valid or invalid training article examples of the denominations and arranged to distinguish therebetween, wherein level data relating to the range or average level of measurement values derived from the training articles is stored, for each of the denominations; processing the measurements derived from test articles using the stored level data to align them with each said stored range for each denomination during the classification process; and forming, for each denomination, a correction factor responsive to the ratio between said level data and a running average of said measurements. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A money validator for classifying a test article as one of a plurality of acceptable denominations of articles of currency, comprising:
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sensor means for deriving a plurality of measurements from said test article; non-linear discriminant means for deriving a plurality of different linear combinations of said measurements and then applying, to each, a respective non-linear compression function (e.g. a sigmoid), to generate a plurality of non-linear output signals; decision means for rejecting a test article or accepting said test article as one of said plurality of denominations, based on said non-linear outputs; and adjustment means for applying a plurality of different adjustments, corresponding to said plurality of denominations, to said measurements to produce a plurality of sets of adjusted measurements, each of which is separately supplied to said means for producing a plurality of linear combinations.
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27. A money validator for classifying a test article as one of a plurality of acceptable denominations of articles of currency, comprising:
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sensor means for deriving a plurality of measurements from the test article defining a point in measurement space; non-linear discriminant means for providing a plurality of discriminants which partition said measurement space into at least one acceptance region corresponding to at least one of said plurality of acceptable denominations, by deriving a plurality of different linear combinations of the measurements and then applying, to each, a respective non-linear compression function (e.g. a sigmoid), to generate a plurality of non-linear output signals; means for applying an additional acceptance boundary test which limits the volume of the acceptance region in said measurement space which would otherwise be applied by said validator; and decision means for rejecting a test article or accepting the test article as one of said plurality of denominations, based on the non-linear output signals in dependence on whether the point lies within the acceptance region.
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28. A method for classifying a test article as one of a plurality of acceptable denominations of articles of currency, comprising:
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deriving a plurality of measurements from the test article defining a point in measurement space; providing a plurality of discriminants which partition said measurement space into at least one acceptance region corresponding to at least one of said plurality of acceptable denominations, by deriving a plurality of different linear combinations of the measurements and then applying, to each, a respective non-linear compression function (e.g. a sigmoid), to generate a plurality of non-linear output signals; applying an additional acceptance boundary test which limits the volume of the acceptance region in said measurement space which would otherwise be applied by said validator; and rejecting a test article or accepting the test article as one of said plurality of denominations, based on the non-linear output signals in dependence on whether the point lies within the acceptance region.
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Specification