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US 8,076,643 B2Granted
Detection apparatus and method
AssigneeFiltrona United Kingdom Limited
InventorsPhilip John Allen, Andrew John Gilbert
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AssigneeFiltrona United Kingdom Limited
InventorsPhilip John Allen, Andrew John Gilbert
Estimating the term…
A technique and apparatus for detection of infrared radiation emitted from a taggant material sample following the excitation of the sample are described. The decay time of the radiation is a function of the particular taggant being used and so, if the decay characteristic or signature is accurately measured, the particular taggant can be accurately identified. The apparatus comprises an electronic controller (10), a pair (12) of illuminating light-emitting diodes, a photo-detector (14), a first amplifier (16), a three-way sampling switch (18), filter/stores (20)(a-c), second amplifiers (22)(a-c) and an output display (26). The infrared emission is excited by repeatedly illuminating the material for a period of microseconds every few milliseconds using a very intense source of infrared light. This light is supplied by the pair of 940 nm, light-emitting diodes (12). Once this light source has been turned off, the sample continues radiating infrared light for a few milliseconds. The emission is detected by photo-detector (14) that is only sensitive to infrared light in the 800 to 1000 nm waveband. This helps to reject interference from visible light sources.
Detection apparatus for determining the presence, absence or characteristic of a security ink on a sample, the apparatus comprising:
A method of determining the presence, absence or characteristic of security ink on a sample, the method comprising:
Detection apparatus for determining the presence, absence or characteristic of a security ink on a sample, said ink characterized by a emission frequency spectrum of radiation in response to a frequency spectrum of excitation radiation illuminated upon said security ink, said apparatus comprising:
A method of identifying a taggant comprising the steps of:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Detecting, e.g. by using light barriers: using one transmitter and one receiver
Visible light, infrared or ultraviolet radiation: testing spectral properties
Printing processes to produce particular kinds of printed work, e.g. patterns: security printing
Geophysics
About 2 months of term left · ends 18 Dec 2026 (estimated)
The present invention relates to a detector and a method for detecting the presence/absence and/or nature of a security mark on an article.
In the field of product or document security it is known to place a machine readable mark on an article or its packaging, which mark can be read by a detector to identify the article and/or to verify the authenticity or otherwise of the article. Such a mark may typically be printed on the article, and may be invisible to the naked eye.
For example, there exist particularly sophisticated, complex inks which reliably emit radiation with certain characteristics under exposure to radiation in a certain frequency range. Such complex inks, which are by their nature difficult for counterfeiters to manufacture include inks known as taggant inks.
A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
FIG. 1 shows a graph of emitted radiation against time following illumination of various samples of security ink;
FIG. 2 shows a graph in which the measurements of the graph of FIG. 1 have been standardised;
The technique for detection used in embodiments of the present invention relies upon the measurement of the decay time of infrared radiation emitted from a taggant material sample following the excitation of the sample. The decay time is a function of the particular taggant being used and so, if the decay characteristic or signature is accurately measured, the particular taggant can be accurately identified.
FIG. 1 illustrates typical outputs from various taggants (A-C) that have been excited by a short burst of high intensity infrared light. Whilst the shape of each decay response is fixed for a particular taggant type, the absolute values that are measured vary over a wide range, dependent on material density, the size of the sample, the substrate material, the proximity of the detector and the strength of the illumination.
However, if the first sample from each taggant is taken as a REFERENCE point and then each of the plots is standardised to have the same initial value, the result shown in FIG. 2 is obtained.