Claims
- 1. A method of testing coins for thickness utilizing first and second inductors positioned on respective sides of a coin path, comprising: `producing separate first and second inductor output values each indicative of the effects of a coin on an electromagnetic field as detected by the respective one of the first and second inductors, each said inductor output values depending upon the position of the coin across the width of the coin path relative to the respective said inductor, the dependency of the first inductor output value upon coin position differing from the dependency of said second inductor output value upon coin position within at least a limited range of coin positions; and
- processing at least the first inductor output value and combining the inductor output values so as to generate a thickness indicating signal, the processing of the first inductor output value being different to that, if any, of the second inductor output value so as to substantially compensate said thickness indicating signal for the effects of the dependency difference between the first and second inductor output values.
- 2. A method as claimed in claim 1, in which the dependence of at least the first inductor output value upon coin position is non-linear, and wherein the processing of said first inductor output value is such as to generate a first processed inductor output value which has a linear gradient of dependence upon coin position, said processed first inductor output value being combined with a further value derived from said second inductor which has substantially the same gradient of dependence upon coin position.
- 3. A method as claimed in claim 1, wherein the processing is achieved using a look-up table which correlates output values with processed values.
- 4. A method as claimed in claim 1, wherein the processing results in a scaling of one of the inductor output values with respect to the other to produce a pair of combinable values which alter substantially in proportion to changes in the position of the coin between the inductors with substantially the same constant of proportionally, at least over a region which corresponds to a likely maximum variation in the position of a coin of a particular denomination.
- 5. A method as claimed in claim 4, the method including the step of testing a coin to determine whether its thickness corresponds to any one of a plurality of different thicknesses each associated with a respective coin denomination, and applying different scaling factors depending on the thickness for which the coin is being tested.
- 6. A method as claimed in claim 1, wherein the inductor output values are representative of said coin effects detected at substantially the same instant.
- 7. A method as claimed in claim 6, including the step of successively combining processed values, and peak-detecting the results in order to obtain the thickness-indicating signal.
- 8. A method as claimed in claim 6, including the step of using the output values of one of the inductors to determine a time when a peak in the output values has occurred, and processing and combining the inductor output values which were produced by said inductors substantially at said time.
- 9. A method as claimed in claim 1, including the step of producing the first and second inductor output values of the inductors in succession as the coin passes the inductors.
- 10. A method as claimed in claim 1, including the step of using a single one of the inductors to detect arrival of a coin in a coin validator, and the further step of powering-up predetermined portions of the coin validator in response to said detection.
- 11. A method as claimed in claim 1, further comprising the steps of digitizing said first and second inductor output values, and processing the first and second inductor output values, using stored data, for balancing the dependence of contributions made by the first and second inductor output values to the thickness indicating signal for a plurality of positions between the inductors.
- 12. Coin validation apparatus comprising:
- means defining a path for conveying a coin travelling in edge-first orientation, said path being sufficiently wide to permit the coin to adopt different positions in a direction transverse to the direction of the path;
- first and second inductors positions on respective sides of the path, the first and second inductors being operable to sense changes in an electromagnetic field caused by the passage of the coin between the inductors and to supply respective first and second inductor output values indicative of said changes, there being a gradient difference between the gradients of the respective dependencies of the first and second inductor output values upon the position of a coin within said path relative to the inductors; and
- processor means for accepting the inductor output values and for performing a conversion process in which at least the first output value is modified, and for producing a thickness indicating signal from a combination of the inductor output values, the conversion process modifying the first inductor output value differently than the modification, if any, of the second inductor output value to substantially compensate said thickness indicating signal for the gradient difference.
- 13. Apparatus as claimed in claim 12, wherein said conversion process is arranged such that the inductor output values which are combined are substantially linearly dependent upon the position of the coin between said inductances, with substantially the same constant of proportionality.
- 14. Apparatus as claimed in claim 12, wherein said conversion process is operable to cause a scaling of one of the inductor output values with respect to the other.
- 15. Apparatus as claimed in claim 12, wherein said processor means is operable to test the inductor output values caused by a passing coin to determine whether its thickness corresponds to any one of the plurality of different thicknesses each associated with a respective coin denomination, and wherein said processor means is operable to perform said conversion process such that different scaling factors are applied to at least one of the inductor output values depending upon the thickness of which the coin is being tested.
- 16. Coin validator apparatus comprising:
- means for defining a path for conveying a coin travelling in edge first orientation, said path being sufficiently wide to permit the coin to adopt different positions in a direction transverse to the direction of the path;
- first and second inductors positioned on respective sides of the path, the first and second inductors being operable to sense changes in the electromagnetic field caused by the passage of the coin between the inductors and to supply respective first and second inductor output values indicative of said changes;
- store means for storing a plurality of different linear weighting data values;
- scaling means for receiving the first and second inductor output values and for generating therefrom a plurality of linearly weighted sum values corresponding to the sum of the first inductor output value multiplied by a first stored weighting value and the second inductor output value multiplied by a second stored weighting value; and
- windowing means for testing each of said linearly weighted sum values against the respective acceptance window.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8917258.9 |
Jul 1989 |
GBX |
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Parent Case Info
This is a continuation-in-part of application Ser. No. 07/828,809 filed on Feb. 27, 1992, now abandoned.
US Referenced Citations (4)
Foreign Referenced Citations (8)
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0146251 |
Jun 1985 |
EPX |
0203702 |
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EPX |
2646025 |
Apr 1978 |
DEX |
57-24803 |
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JPX |
62-164190 |
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JPX |
8600410 |
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WOX |
2207270 |
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GBX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
828809 |
Feb 1992 |
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