Patent EP0314312A2 successfully refreshed from Google Patents.
EP0314312A2
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Method and apparatus for detecting inks
Assignee: De la Rue Systems Ltd
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Filing: 1988-10-03
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Granted: —
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Expires: 2008-10-03
Abstract
Abstract Apparatus for detecting the presence of an ink on a substrate comprises a number of LEDs (1) for irradiating the substrate (2) with radiation at at least two different wavelengths, at least one of the wavelengths being chosen to correspond to an absorption or reflectance wavelength of the ink to be detected. A sequence generator (5) modulates the radiation at each wavelength in a respective, different manner. A radiation sensor (3) senses radiation emitted by the substrate (2). A correlator (7,8) correlates samples of the sensed radiation from the radiation sensor (3) with signals each of which is modulated by a respective one of the modulations applied to the radiation, to generate correlation signals. A monitor (9) monitors the correlation signals in order to detect the presence of the said ink.
Inventors
- 👤 Anthony Martin
- 👤 Paul Dennis Lacey
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 14:50
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/46; G07; G07D; G07D7/00; G07D7/06; G01J3/50; G01J3/501
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
111 words
A method of detecting the presence of an ink on a substrate, the method comprising irradiating the substrate with radiation at at least two different wavelengths, the radiation at each wavelength being modulated in a respective, different manner, and at least one of the wavelengths being chosen to correspond to an absorption or reflection wavelength of the ink to be detected; sensing radiation emitted from the substrate and correlating samples of the sensed radiation with signals each of which is modulated by a respective one of the modulations applied to the radiation, to generate correlation signals; and monitoring the correlation signals in order to detect the presence of the said ink.
Claim 2
Independent Claim
111 words
A method of detecting the presence of an ink on a substrate, the method comprising irradiating the substrate with radiation at at least two different wavelengths, the radiation at each wavelength being modulated in a respective, different manner, and at least one of the wavelengths being chosen to correspond to an absorption or reflection wavelength of the ink to be detected; sensing radiation emitted from the substrate and correlating samples of the sensed radiation with signals each of which is modulated by a respective one of the modulations applied to the radiation, to generate correlation signals; and monitoring the correlation signals in order to detect the presence of the said ink.
Claim 3
Dependent Claim
18 words
A method according to claim 1, wherein the modulations comprise phase shifted versions of a common modulation sequence.
Claim 4
Dependent Claim
17 words
A method according to claim 1 or claim 2, wherein the modulation comprises a pseudo-random binary sequence.
Claim 5
Independent Claim
29 words
A method according to any of the preceding claims, wherein one of the wavelengths lies in the optical range, and another of the wavelengths lies outside the optical range.
Claim 6
Independent Claim
41 words
A method according to any of the preceding claims, wherein the correlating step comprises multiplying each sample of the sensed radiation with a respective one of the modulated signals and integrating the resultant multipled signals over a cycle of the modulation.
Claim 7
Independent Claim
20 words
A method according to any of the preceding claims, wherein the sensing step comprises sensing radiation reflected by the substrate.
Claim 8
Dependent Claim
134 words
Apparatus for detecting the presence of an ink on a substrate, the apparatus comprising irradiating means (1) for irradiating the substrate (2) with radiation at at least two different wavelengths, at least one of the wavelengths being chosen to correspond to an absorption or reflectance wavelength of the ink to be detected; modulation means (5) for modulating the radiation at each wavelength in a respective, different manner; radiation sensing means (3) for sensing radiation emitted by the substrate; correlating means (7,8) for correlating samples of the sensed radiation from the radiation sensing means with signals each of which is modulated by a respective one of the modulations applied to the radiation, to generate correlation signals; and monitoring means (9) for monitoring the correlation signals in order to detect the presence of the said ink.
Claim 9
Dependent Claim
134 words
Apparatus for detecting the presence of an ink on a substrate, the apparatus comprising irradiating means (1) for irradiating the substrate (2) with radiation at at least two different wavelengths, at least one of the wavelengths being chosen to correspond to an absorption or reflectance wavelength of the ink to be detected; modulation means (5) for modulating the radiation at each wavelength in a respective, different manner; radiation sensing means (3) for sensing radiation emitted by the substrate; correlating means (7,8) for correlating samples of the sensed radiation from the radiation sensing means with signals each of which is modulated by a respective one of the modulations applied to the radiation, to generate correlation signals; and monitoring means (9) for monitoring the correlation signals in order to detect the presence of the said ink.
Claim 10
Dependent Claim
30 words
Apparatus according to claim 7, wherein the radiation sensing means (3) comprises a common sensor for receiving radiation at each of the different wavelengths generated by the irradiating means (1).
Claim 11
Dependent Claim
86 words
Apparatus according to claim 7 or claim 8, wherein the correlating means comprises a number of multiplying circuits (7), one for each wavelength, each multiplying circuit receiving a sample of the radiation sensed by the radiation sensing means and a signal which has been modulated in the same way as the radiation wavelength corresponding to that multiplying circuit; and integrating means (8) to which the output signal from the multiplying circuit is fed, the integrating means integrating the incoming signal over a cycle of the modulation.
Claim 12
Dependent Claim
26 words
Apparatus according to any of claims 7 to 9, wherein the modulating means (5) causes each wavelength to be modulated in a respective pseudo-random binary sequence.
Claim 13
Dependent Claim
30 words
Apparatus according to any of claims 7 to 10, wherein the modulating means (5) modulates the radiation at each wavelength with respective phase shifted versions of a common modulation sequence.
References Cited (Backward Citations)
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