EP0072236A2
Expired / Lapsed
EP
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Apparatus for detecting tape on sheets
Assignee: De la Rue Systems Ltd
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Filing: 1982-08-09
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Granted: —
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Expires: 2002-08-09
Abstract
Abstract Apparatus is disclosed for detecting the presence of shiny tape on a printed note, for example a banknote. An optical fibre fishtail array supplies visible light from a source (A) to a lengthwise strip of the banknote. A first array of photodetectors (D) detects light specularly reflected from a plurality of adjacent regions of the said strip, while a second array (B) arranged parallel to the first array (D) detects light reflected diffusely from corresponding ones of the said regions. An analysing circuit receives signals from the photodetectors and indicates when the ratio of specularly reflected light from an illuminated element of the banknote to diffusely reflected light from the same element exceeds a predetermined value.
Inventors
- 👤 Christopher Paul Chapman
- 👤 Victor Brian Chapman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 16:45
CPC Classifications
G; G07; G07D; G07D7/00; G07D7/06; G07D7/12
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
229 words
Apparatus for sensing the condition of the surface of a sheet, comprising means (A) for illuminating an element of the surface, means for receiving light reflected from the illuminated element and for converting such light into an electric signal, and signal-analysing means responsive to the said signal to indicate the presence of a flaw at that element of the surface, characterized in that to detect the presence of shiny tape on a moving printed noted the illuminating means directs collimated beams of light at a plurality of adjacent regions forming a strip across the note in a direction perpendicular to its movement and in that the light-receiving means comprises a first array of light receivers (D) arranged to receive light specularly reflected from the plurality of adjacent illuminated regions and to provide corresponding electric signals, and a second array of light receivers (B) arranged to detect light diffusely reflected from corresponding ones of the said regions and to provide corresponding electric signals, the apparatus further comprising signal-analysing means (12, 13, 14) receiving the signals from both arrays of light receivers and responsive to an increase in the ratio of the instantaneous values of the signals representing light reflected specularly and light reflected diffusely from any one of the said regions to provide a signal output indicative of the presence of shiny tape on the illuminated surface of the note.
Claim 2
Dependent Claim
229 words
Apparatus for sensing the condition of the surface of a sheet, comprising means (A) for illuminating an element of the surface, means for receiving light reflected from the illuminated element and for converting such light into an electric signal, and signal-analysing means responsive to the said signal to indicate the presence of a flaw at that element of the surface, characterized in that to detect the presence of shiny tape on a moving printed noted the illuminating means directs collimated beams of light at a plurality of adjacent regions forming a strip across the note in a direction perpendicular to its movement and in that the light-receiving means comprises a first array of light receivers (D) arranged to receive light specularly reflected from the plurality of adjacent illuminated regions and to provide corresponding electric signals, and a second array of light receivers (B) arranged to detect light diffusely reflected from corresponding ones of the said regions and to provide corresponding electric signals, the apparatus further comprising signal-analysing means (12, 13, 14) receiving the signals from both arrays of light receivers and responsive to an increase in the ratio of the instantaneous values of the signals representing light reflected specularly and light reflected diffusely from any one of the said regions to provide a signal output indicative of the presence of shiny tape on the illuminated surface of the note.
Claim 3
Dependent Claim
103 words
Apparatus in accordance with claim 1, wherein the illuminating means comprises an optical fibre fishtail array (Figure 5), the bunched end of the array being adjacent to a single source of light and the other end of the array providing a line of fibre optic ends for illuminating a strip of the note, and in which each of the first and second arrays of light receivers is also in the form of an optical fibre array, the input ends of the optical fibres forming a line parallel to the output ends of the illuminating optical fibres for receiving light reflected from the note.
Claim 4
Dependent Claim
31 words
Apparatus in accordance with claim 2, wherein the collimated beam of light is produced with the aid of a lens system in conjunction with the optical fibres of the illuminating means.
Claim 5
Dependent Claim
34 words
Apparatus in accordance with claim 2, wherein the collimated beams of light are produced by arranging that each fibre of the fishtail array of the illuminating means has a numerical aperture less than 0.3.
Claim 6
Dependent Claim
13 words
Apparatus in accordance with claim 4, wherein the numerical aperture is approximately 0.19.
Claim 7
Dependent Claim
26 words
Apparatus in accordance with any of the preceding claims, wherein the light with which the note is illuminated is in the visible region of the spectrum.
References Cited (Backward Citations)
No citation records indexed.
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