Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1997-12-01
2001-06-12
Frech, Karl D. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S491000, C235S493000
Reexamination Certificate
active
06244508
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a document of value, such as a check or ID card or the like, having information specific to the document, in particular user-related data, and to a method for testing the authenticity of the document of value.
2. Related Art
In view of modern reproduction techniques, in particular the rising quality of color copiers, it is becoming ever easier to reproduce documents of value with relatively little effort. This increases the danger of forgeries.
In order to counteract this development one has proposed protecting papers of value by a special coding (DE 24 58 705 A1). Individual parameters of the document, such as characteristic color or print properties, are measured and deposited on the document in coded form. If the coding is to be invisible to the eye one can use luminescent printing inks which are transparent in the visible spectral region. When checking the authenticity of the document one measures the characteristic parameters and compares them with the measuring data stored on the document in coded form.
This procedure offers good protection from forgery as long as the documents of value are coded centrally in protected surroundings and luminescent substances are used which are virtually unavailable commercially.
In the case of check forms having user-related information, such as the account number, it is frequently also useful to include these data in the coding in order to ensure that these data have not been manipulated (i.e., altered). However, checks are usually personalized in decentralized fashion, i.e. the blank forms are produced centrally and then passed on to the issuing bank which applies the user-related data. To permit the method known from DE 24 58 705 A1 to be applied to the user-related data of the check, each bank would therefore have to be equipped with the corresponding devices for applying the coding and in particular the corresponding luminescent substances. This would sacrifice part of the forgery-proof effect since it would make the equipment required for coding much more easily accessible and thus increase the danger of misuse.
The invention is therefore based on the problem of proposing a document of value which avoids the disadvantages of the prior art.
BRIEF SUMMARY OF THE INVENTION
The inventive paper of value has in a certain area a luminescent background partially masked by a color contrasting substance, e.g. a nonluminescent printing ink. The shape and arrangement of the mask result in a coding which is correlated with data specific to the document.
When the coding is read the document is illuminated with excitation radiation for the luminescent substance. A detector which is sensitive only in the spectral region of the luminescent radiation will recognize only the luminescent areas as “light” areas. The rest of the document and the mask in the luminescent area will appear dark to the sensor, provided the mask does not (substantially) reflect or emit in the wave range of the luminescent radiation. In this way a strong contrast between background and mask is produced which permits easy reading of the coding.
At the same time the inventive document has the crucial advantage that the luminescent background can be designed the same way for all documents of value and thus be decoupled from the coding or personalizing process. It is thus possible to apply the luminescent background centrally in protected surroundings, the mask being applied in the form of a coding at a later time, e.g. during personalization of the document of value. For the mask one can use conventional printing inks.
The background, however, is preferably applied using special luminescent substances which are virtually unavailable commercially. This has the additional advantage that when checking the element one can ascertain in a first step whether the luminescent substance is “authentic” with reference to one or more measurable, characteristic properties of the luminescent substance.
According to a preferred embodiment the document of value has a luminescent background stripe applied to a suitable place on the document. The coded information in the form of a bar code, preferably containing portions of the user-related data, is printed in the luminescent stripe using a conventional printing process, e.g. by a laser printer, matrix printer or offset printing machine.
Finally, one can further increase the protection from forgery by applying the luminescent background, not as an all-over coating, but in the form of geometrical structures which are small yet resolvable visually or by machine. This permits better recognition of any attempts at alterations in the area of the background. If an attempt is made to change the mask with chemical means, the structures blur. If a luminescent substance emitting in the visible spectral region is used, for example, these changes can be recognized very easily upon excitation of the substance, so that it is possible to discover alterations even without machine testing of the correspondence between code and read information.
According to a further inventive embodiment the document can additionally be provided with magnetic information which is correlated with the coded information in the area of the luminescent background. In the simplest case the basic information to be represented in both ways is coded once and deposited on the document of value merely in different modes of representation, once by application of magnetic material and once by masking a luminescent background. According to a variant one can also use different coding algorithms for the different forms of representation of the code. It is also conceivable for the magnetic code and the code represented by the luminescent substance to represent different pieces of information which complement each other or have a certain mutual relationship.
During authenticity testing or the document, both coded pieces of information are read and checked for agreement or for the predetermined mutual relationship. By reason of the special testing method for the code represented with the aid of the luminescent background, one can simultaneously ascertain whether alterations have been performed in the luminescent area or on the magnetic information.
This is because when the coded information in the area of the luminescent background is read the detector quasi simultaneously recognizes the printed coding, i.e. the mask itself, and records the signal of the luminescent background. In the area of the coding, i.e. the mask of the luminescent background, this signal is very small or almost zero. Consequently there is a direct correlation between the two signal curves measured by the detector, which is absent only in the case of alterations.
Further embodiments and advantages of the invention will be explained with reference to the figures, in which:
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Bacon & Thomas
Cyr Daniel St.
Frech Karl D.
Giesecke & Devrient GmbH
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