Method of testing documents provided with optico-diffractively effective markings
AssigneeWHD Electronische Prueftechnik
InventorFrank Puttkammer
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Abstract
The invention relates to a method of examining the authenticity of a document provided with an optico-diffractively effective element or hologram by subjecting the hologram to capacitive coupling of a voltage and deriving a signal representative of the voltage for comparison with a reference signal representative of a hologram of an authentic document. The method may be improved by providing, between individual segments of the hologram, additional security indicia providing a signal in response to being irradiated by electromagnetic radiation of a predetermined frequency.
Claims9
A method of testing the authenticity of a document provided with at least one optico-diffractively effective security indicium[[,]] comprising a pattern of metallization of different electrical conductivities, comprising the steps of:
- storing a signal representative of said electrical conductivity of the security indicium of a genuine document;
- moving a document along a predetermined path;
- capacitively coupling a voltage to the security indicium;
- measuring the voltage in the security indicium and deriving therefrom a signal representative of the different electrical conductivities;
- and
- comparing the derived signal against the stored signal.
A device for testing the authenticity of a document provided with at least one optico-diffractively effective security indicium comprising a pattern of metallization of different electrical conductivities, comprising:
- memory for storing a signal representative of said electrical conductivity of the security indicium of a genuine document;
- structure for moving a document along a predetermined path;
- structure for capacitively coupling a voltage to the security indicium;
- structure for measuring the voltage in the security indicium and deriving therefrom a signal representative of the different electrical conductivities;
- and
- structure for comparing the derived signal against the stored signal.
A method of making device for testing the authenticity of a document provided with at least one optico-diffractively effective security indicium comprising a pattern of metallization of different electrical conductivities, said method comprising:
- providing memory for storing a signal representative of said electrical conductivity of the security indicium of a genuine document;
- providing structure for moving a document along a predetermined path;
- providing structure for capacitively coupling a voltage to the security indicium;
- providing structure for measuring the voltage in the security indicium and deriving therefrom a signal representative of the different electrical conductivities;
- and
- providing structure for comparing the derived signal against the stored signal.
Dependencies are inferred from the claim text.