Printed matter – Having revealable concealed information – fraud preventer or... – Utilizing electromagnetic radiation
Patent
1992-09-30
1994-10-11
Eley, Timothy V.
Printed matter
Having revealable concealed information, fraud preventer or...
Utilizing electromagnetic radiation
283 82, 283 83, 428915, 427131, 427282, 427511, B42D 1502, B05D 512
Patent
active
053540999
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a security document, in particular a bank note, identity card or the like, having a security element which is provided with characters, patterns, etc., visually readable at least in transmitted light and which is electrically conductive and bears additional substances for machine testing, and to a method for producing such a security element.
German patent no. 27 54 267 discloses equipping a security element, generally referred to as a safeguarding thread, with several security features. In particular this publication describes the combination of a magnetic authenticity feature with another physical feature, such as electric conductivity or luminescence. An important selection criterion for the security features to be combined is that these features not be readily recognizable and imitatable by a forger. This requirement of course increases the protection against forgery. However, it also means that an average persons who handles such security documents are likewise unable to detect these security features and that security documents equipped with such a thread cannot be checked for authenticity without suitable machines.
To avoid this disadvantage EP-A 0 330 733 therefore proposes a security element that can be checked both visually and by machine. For this purpose a transparent plastic film is metal-coated and this coating is provided with recesses in the form of characters or patterns. The safeguarding thread also contains a chromophore and/or luminescent substances in the areas congruent with the recesses for making the characters or patterns contrast in color with the opaque metallic coating under suitable light conditions. A special method is used for producing the recesses, the so-called negative writing. Before the thread material is metalized, a printed image is applied in accordance with the later recesses and only then the metallic coating is applied. The printed image is applied using inks or lacquers that can be chemically dissolved again under the metallic coating, giving rise to recesses in the metallic layer at those places in the printed image since the metallic layer is removed along with the ink.
The safeguarding thread described in EP-A 0 330 733 meets a very high security standard. On the one hand, the electric conductivity can be checked by machine via the uninterrupted metallic coating and, on the other hand, the negative writing serves as a visual authenticity feature well recognizable to the viewer. Furthermore, the thread has an additional feature not readily recognizable to the viewer, namely luminescence in the area of the negative writing that can likewise be checked by machine. However, it is disadvantageous that a testing device must have both a conductivity sensor and an optical sensor for detecting the two machine-testable properties. Optical sensors are relatively elaborate and voluminous due to the necessary light source, lens systems, filters, etc. This makes the testing device accordingly elaborate and large.
The invention is therefore based on the problem of providing a security element for security documents having at least two machine-testable security features that avoids the abovementioned disadvantages and nevertheless combines the advantages of the visual and machine testability.
This problem is solved by the features stated in claims 1, 21 and 22.
The essence of the invention is the combination of a magnetic security feature with negative writing that offers several advantages. Firstly, the inventive security element advantageously combines the positive aspects of prior art security elements, fast and simple visual checking, on the one hand, and the possibility of machine testing that is not readily recognizable from the outside, on the other. This is because the negative writing, that is embedded in reflective surroundings, is readily detected by the human eye and can be easily checked for authenticity by the viewer. It is additionally possible to support, or possibly revise, the visual test result for the security document by m
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Boehm Michael
Kaule Wittich
Eley Timothy V.
GAO Gesellschaft fur Automation und Organisation mbH
Nguyen K. V.
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