EP0072237A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Apparatus for scanning a sheet
Assignee: De la Rue Systems Ltd
•
Filing: 1982-08-09
•
Granted: —
•
Expires: 2002-08-09
Abstract
Abstract Apparatus is disclosed for scanning a banknote (33). A lengthwise strip of the banknote (33) is illuminated with white light, and the banknote is moved parallel to its width. Light reflected from all regions of the lenghtwise strip is conveyed through an optical fibre fishtail array to a single photodetector, or to a spectroscope and thence to several photodetectors for colour scanning. The waveform produced by the or each photodetector is then characteristic of the surface of the banknote, and is used in an analysing circuit for banknote pattern recognition, or to sense the condition of the banknote with regard to its age or degree of soiling. The analysing circuit includes means for compressing or expanding the lenght of the waveform to give it a standard lenght for subsequent comparison with one or more stored characteristic waveforms in a memory (16). The apparatus also determines the mean level of intensity of the waveform in an integrator (9), and includes a circuit (24 to 28) for obtaining the standard deviation of selected points of the waveform from the mean value, a low standard deviation indicating a badly soiled or worn banknote.
Inventors
- 👤 Barry John Curl
- 👤 Victor Brian Chapman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 07:54
CPC Classifications
G; G07; G07D; G07D7/00; G07D7/06; G07D7/12; G07D7/121; G07D7/1205; G07D7/181; G07D7/187; G07D7/20
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
83 words
Apparatus for scanning a sheet comprising: means for illuminating the sheet; means for collecting light from an illuminated strip of the surface of the sheet; means responsive to the light collected from all regions of the strip to produce a summed intensity signal; means for moving the sheet relative to the light collector in a direction substantially perpendicular to the strip; and analysing means responsive to successive summed intensity signals to create a waveform which is characteristic of the surface of the sheet.
Claim 2
Dependent Claim
83 words
Apparatus for scanning a sheet comprising: means for illuminating the sheet; means for collecting light from an illuminated strip of the surface of the sheet; means responsive to the light collected from all regions of the strip to produce a summed intensity signal; means for moving the sheet relative to the light collector in a direction substantially perpendicular to the strip; and analysing means responsive to successive summed intensity signals to create a waveform which is characteristic of the surface of the sheet.
Claim 3
Dependent Claim
18 words
Apparatus in accordance with claim 1, wherein the means responsive to the collected light is a single photodetector.
Claim 4
Dependent Claim
44 words
Apparatus in accordance with claim 2, wherein the means for collecting light from the strip is a fibre optic fishtail array, the wide end of which is arranged adjacent to the said strip, and the narrow end of which delivers light to the photodetector.
Claim 5
Dependent Claim
33 words
Apparatus in accordance with any preceding . claim, wherein the means for illuminating the strip consists of a fibre optic fishtail.array, the wide end of which is arranged adjacent to the said strip.
Claim 6
Dependent Claim
60 words
Apparatus in accordance with any preceding claim for scanning banknotes, wherein the illuminated strip is longer than the length of the banknote, light from the whole of this length being delivered to the means responsive to collected light, and wherein the means for moving the sheet comprises a conveyor which moves the banknote in a direction parallel to its width.
Claim 7
Dependent Claim
64 words
Apparatus in accordance with any of claims l to 4, wherein at least one other strip is illuminated, parallel to and separate from the said illuminated strip, and the apparatus includes corresponding means responsive to light collected from these strips, wherein the analysing means is responsive to the successive summed intensity signals corresponding to each strip to derive a corresponding plurality of characteristic waveforms.
Claim 8
Dependent Claim
61 words
Apparatus in accordance with claim 6, wherein the said illuminated strip and the said other strip are of equal width and are equidistant from the centre of the sheet, so that changing the orientation of the sheet simply results in the same two bands being scanned in reverse, resulting in the waveforms from the two strip scanners being interchanged and reversed.
Claim 9
Dependent Claim
56 words
Apparatus according to any preceding claim, comprising a memory for storing the characteristic waveform of a sheet for subsequent comparison with another sheet, wherein the apparatus works in two alternative modes, a first mode being for recording the waveform in the memory, and a second mode being for comparing a currently-produced waveform with a stored waveform.
Claim 10
Dependent Claim
34 words
Apparatus according to claim 8, wherein the apparatus when in the compare mode makes a simultaneous comparison of the currently-produced waveform with a reversed stored waveform corresponding to the opposite orientation of the sheets.
Claim 11
Dependent Claim
65 words
Apparatus according to any preceding claim, further including a circuit for determining the mean level of the successive summed intensity signals, and comparing each successive summed intensity signal with the said mean level, the differences between the signal level and the means level then being processed so as to provide a signal representing the standard deviation of the successive summed intensity signals from the mean.
Claim 12
Dependent Claim
102 words
ll. Apparatus for scanning a sheet comprising: means for illuminating the sheet; means for collecting light from an illuminated strip of the sheet; means responsive to the light collected from all regions of the strip to provide a set of colour intensity signals, each representative of the intensity of a different group of wavelengths of the collected light; means for moving the sheet relative to the light collector in a direction substantially perpendicular to the strip; and analysing means responsive to successive summed colour intensity signals to create waveforms for each colour, the waveforms being characteristic of the surface of the sheet.
Claim 13
Dependent Claim
102 words
ll. Apparatus for scanning a sheet comprising: means for illuminating the sheet; means for collecting light from an illuminated strip of the sheet; means responsive to the light collected from all regions of the strip to provide a set of colour intensity signals, each representative of the intensity of a different group of wavelengths of the collected light; means for moving the sheet relative to the light collector in a direction substantially perpendicular to the strip; and analysing means responsive to successive summed colour intensity signals to create waveforms for each colour, the waveforms being characteristic of the surface of the sheet.
Claim 14
Dependent Claim
67 words
Apparatus according to claim 11, comprising a memory for storing the characteristic colour waveforms of a sheet for subsequent comparison with respective waveforms of another sheet, wherein the apparatus works in two alternative modes, the first mode being for recording the waveforms in the memory, and the second mode being for comparing currently-produced waveforms with stored waveforms, to determine the stored waveform which produces the best match.
Claim 15
Dependent Claim
59 words
Apparatus according to claim 11 or 12 comprising a plurality of photodetectors responsive to the different wavelengths of light, each photodetector arranged to receive light from the said collecting means, wherein the analysing means takes successive summed intensity signals from each photodetector in rotation, so that the summed intensity for any given wavelength is sampled periodically during the scan.
Claim 16
Dependent Claim
45 words
Apparatus according to claim 13, including means for normalizing the length of the characteristic waveform of each colour separately, to ensure that regions of a scanned banknote are compared with corresponding regions of a standard banknote, on the basis of the same group of wavelengths.
Claim 17
Dependent Claim
193 words
An electronic circuit for correlating two waveforms, comprising: an expanding circuit comprising a first delay of a predetermined capacity N t , means for clocking a first waveform signal into the first delay, the first waveform then occupying a variable number N of bits of the first delay, means for counting the length N of the first waveform and storing it, means for clocking the first waveform out of the first delay at a first clocking frequency and into a second delay at a second clocking frequency, the ratio of the first and second clocking frequencies being dependent on the ratio N W : N t , such that the waveform is expanded to fill exactly the second delay; a store for storing a waveform from the second delay in digital form; correlating means for comparing the second waveform stored previously in the said store, bit by bit with corresponding bits of the first waveform taken from the second delay, the first and second waveforms being of identical length; and means responsive to the correlating means to provide an output signal indicative of the degree of correlation of the first and second waveforms.
Claim 18
Dependent Claim
193 words
An electronic circuit for correlating two waveforms, comprising: an expanding circuit comprising a first delay of a predetermined capacity N t , means for clocking a first waveform signal into the first delay, the first waveform then occupying a variable number N of bits of the first delay, means for counting the length N of the first waveform and storing it, means for clocking the first waveform out of the first delay at a first clocking frequency and into a second delay at a second clocking frequency, the ratio of the first and second clocking frequencies being dependent on the ratio N W : N t , such that the waveform is expanded to fill exactly the second delay; a store for storing a waveform from the second delay in digital form; correlating means for comparing the second waveform stored previously in the said store, bit by bit with corresponding bits of the first waveform taken from the second delay, the first and second waveforms being of identical length; and means responsive to the correlating means to provide an output signal indicative of the degree of correlation of the first and second waveforms.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.