This application claims the priority of European patent application 02010143.2, filed May 13, 2002, the disclosure of which is incorporated herein by reference in its entirety.
The invention relates to a security document, such as a banknote, as well as to a method for encoding information on such a security document and a method for manufacturing it.
Security documents, such as banknotes, cheques, papers of value, passports, identity cards, credit cards or bank cards, are, as a rule, provided with features that make counterfeiting them difficult. Security print features, micro perforations, holograms or inlaid metal threads have e.g. been known.
The problem to be solved by the present invention is to provide a further security feature for a security document of the type mentioned above.
This problem is solved by the object of the independent claims.
Hence, according to the invention, the security document is provided with a resonant electric circuit that can be excited to a resonant oscillation by means of an applied electromagnetic ac field if the field frequency corresponds substantially to the resonance frequency of the resonant circuit. This allows to detect the resonant circuit in contact-less manner.
Preferably, the resonant circuit consists at least in part of an electrically conducting, printable material, which allows a production by means of printing techniques.
In a first preferred embodiment, the security document is a banknote.
In another preferred embodiment the security document comprises several sheets bounds in a binder, such as it is e.g. customary for passports. If the resonant circuit is arranged in or on the binder, it is mechanically protected in a better manner, in particular if the binder is of a less pliable material than the sheets.
A particularly robust arrangement results if the capacitor electrodes of the resonant circuit are arranged on opposite sides of the carrier of the security document.
Several different resonant circuits of differing resonant frequency can be provided as well, which increases security against counterfeiting. In this case, the difference frequency between the resonant frequencies of the resonant circuits can be measured as well.
It is also possible to provide a whole set of banknotes with resonant circuits. In this case, the resonance frequency and/or the arrangement of the resonant circuit can be chosen in dependence of the denomination of the corresponding banknote. The security document can, however, also be designed e.g. as a passport or identity card.
As it has already been mentioned for banknotes, it is also possible to encode an information in the security document by means of the selected resonance frequency or the arrangement of the resonant circuit. Preferably, the resonance frequency is selected in dependence of a further information, wherein the further information is arranged in suitable form (e.g. encoded or in plain text) on the security document. In this case, a authenticity check can be carried out by comparing the information.
Further embodiments, advantages and applications of the invention are disclosed in the dependent claims and the now following description by reference to the figures, which show
The banknote of
The design of the resonant circuits 5 can be seen from
The inductance L and the capacitor C together form a resonant circuit with the resonance frequency.
If the banknote is brought into an electromagnetic ac field with frequency f, the resonant circuit is excited to an oscillation in resonance, which can be detected. Corresponding detection circuits have been known from anti-theft systems and do not have to be described here in detail.
As can be seen from
Preferably, notes of different value are equipped with resonant circuits having different resonance frequency. This allows a determination of the note denomination by means of the resonance frequency and increases the counterfeiting safety. It is also possible to distinguish notes of different countries of origin because of the resonance frequency of their resonant circuit or circuits. Hence, by choosing the resonance frequency of the resonant circuit or circuits, an information can be encoded. This can (as in the embodiment of the note denomination) be an information that stands in relation to a further information printed onto the security document or arranged in another manner thereon. This allows a verification of the authenticity of the document by comparison of the information. Instead of or in addition to encoding of information by means of the resonance frequency, information can also be stored by means of the location of the resonant circuits on the document.
In the embodiment of
The resonant circuits 5 can, however, also be covered by a non-transparent layer 11 and therefore be invisible. They can also be arranged within the carrier 1 instead of on one of its surfaces.
The resonant circuits 5 can be manufactured by applying electrically conducting ink, e.g. of a material that can be applied by printing techniques, such as screen printing. For manufacturing the through contacts 10, one or more holes can be manufactured in the substrate 1, e.g. by means of laser beams, prior to applying the electrically conducting ink. These can then be filled with electrically conducting ink or another electrical conductor.
It is, however, also possible to manufacture the resonant circuits or parts thereof by applying conducting structures in different manner, e.g. in the shape of coatings or foils, on the carrier 1 or into the carrier 1. Further, it is possible to prefabricate the resonant circuit separately from the banknote and then to attach to the same.
An example of this type is shown in
Marking by means of resonant circuits is suited for all security documents, such as documents of value, deeds, or passports. In addition, it is also suited for application on plastic cards, such as identity cards or credit cards.
It is also possible to apply a resonant circuit on the “personalization page” of the passport, i.e. on the page that contains the individualized data of its owner.
While in the present application there are described preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited to the same and can also be carried out in different manner within the scope of the following claims.
Number | Date | Country | Kind |
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02010143.2 | May 2002 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB03/01214 | 3/24/2003 | WO | 4/25/2005 |