Printed matter – Having revealable concealed information – fraud preventer or... – Utilizing electromagnetic radiation
Patent
1988-01-22
1991-04-09
Watts, Douglas D.
Printed matter
Having revealable concealed information, fraud preventer or...
Utilizing electromagnetic radiation
283 85, 235491, G06K 1906, B42D 1500, B42F 2100
Patent
active
050058738
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the marking of articles and in particular to the marking of articles with a characteristic identifying feature which can give a visual indication of the authenticity of the article.
British Patent Specification No. 1123274 discloses an identification document having embedded therein superposed layers of a fluorescent material and an ultraviolet screening agent. The layer of ultraviolet screening agent has a code formed therein so that when the document is illuminated with ultraviolet radiation, the code can be seen. The code is invisible in light containing only small amounts of ultraviolet radiation (e.g. daylight). However such a document, and identification documents generally, are not sufficiently secure against tampering by a skilled forger who wishes to alter the information on the document and also against forging to produce counterfeit documents. In particular, a skilled forger could delaminate the identity document and alter the information thereon before re-laminating the document. Also, a forger could reproduce the superposed layers and incorporate them into a counterfeit document.
There is a growing need for a method of making articles which cannot easily be tampered with even by a skilled forger, or reproduced by an unauthorised person. There is also a growing need for a method of making articles in a way in which any tampering or forging action can be revealed in a simple way by a non-expert person. The present invention aims to fulfill both of those needs.
Accordingly, the present invention provides an article comprising a substrate having markings which are provided by at least two fluorescent materials which have different excitation spectra in the ultraviolet region of the spectrum and different emission spectra in the visible or infra red region of the spectrum.
Preferably, the at least two fluorescent materials are excited to fluoresce at different wavelengths of ultraviolet radiation and when excited fluoresce with different colours in the visible region of the spectrum.
Optionally, each fluorescent material is in a respective fluorescent layer and the fluorescent layers are superposed over each other.
Desirably, each fluorescent layer comprises a plastics material in which the respective fluorescent material is incorporated uniformly and the fluorescent layers are heat bonded together.
Preferably, the heat bonded surface of one of the fluorescent layers has engraved grooves therein into which extends that fluorescent layer which is heat bonded thereto.
In one preferred arrangement, the substrate comprises a base layer and the surface of the base layer which is covered by the superposed fluorescent layers is provided with visual identification data which can be seen through the superposed fluorescent layers.
In another preferred arrangement, there are at least two of the fluorescent layers and between two adjacent fluorescent layers is provided visual identification data.
More preferably, the visual identification data is provided by a pattern of a UV absorbing but visibly transparent material.
Advantageously, the base layer is a layer of plastics material and the base layer and the superposed fluorescent layers are heat bonded together.
One of the fluorescent layers may comprise the substrate, and more preferably the surface of the substrate fluorescent layer which is covered by the or each other fluorescent layer is provided with visual identification data which can be seen through the other fluorescent layer or layers.
Still more preferably, the visual identification data is provided by a pattern of a UV absorbing but visibly transparent material.
In an alternative embodiment of the present invention, the at least two fluorescent materials are in admixture and are contained in a body of material.
Preferably, the body comprises a plastics material and constitutes the substrate.
In a further alternative embodiment of the present invention one of the fluorescent materials is contained in a layer of plastics material, an exposed surface of the layer of p
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Heyrana Sr. Paul M.
Watts Douglas D.
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