Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Patent
1981-10-23
1984-05-29
Ives, P.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
101DIG25, 428918, 4285377, 428908, 428207, 428333, 428403, 428438, 428464, 428690, 428913, 428916, 428917, 25033611, 250365, 356 71, 162162, 283 92, B32B 516, G01J 142
Patent
active
044515308
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a security paper with authenticity features in the form of luminescing substances and a process for the manufacture of the same.
Under the description "security paper" are here to be understood banknotes, check forms, shares and stamps as well as passes, credit cards, check cards, passports, air tickets and other certificates and documents.
Making security papers secure against forgery by means of luminescing substances has already been known for a long time. Already in German Patent Specification No. 449133 of the year 1925 and German Patent Specification No. 497037 of the year 1926 the introduction of luminescing substances into security papers is described, wherein the luminophores used therein can be excited with ultraviolet or other invisible rays and emit in the visible region.
In U.S. Pat. Nos. 3,473,027 and 3,525,698 luminophores and their use as coding colors on the basis of host lattices doped with rare earth metals, which if necessary are coactivated, are described, in which the excitation takes place in the UV-region or in the shortwave visible region and the emission in the visible and also in the IR-region bordering thereon, wherein the emissions in the IR-region are employed for broadening the usable spectral region.
The rare earth metal luminophores described in German Offenlegungsschrift No. 2547768 are excited in the IR-region and emit in the visible region.
The use of luminophores for rendering security papers secure is further described in German Offenlegungsschrift No. 1599011.
Starting from the state of the art relevant to rendering security paper secure using luminescing substances it can be concluded that such luminophores are chosen which are available, the unchanged excitation and emission spectra of which appear to be favorable from the point of view of security and authenticity testing.
Furthermore in the patent literature numerous suggestions have been made for modifying luminophores, for example by combination of the same with other substances or their coating and encapsulation for various purposes including changing the spectral region.
Thus it has, for example, been suggested to improve the chemical resistance of luminophores by coating with certain substances. In the case of luminous screens for the multi-colour presentation of images, part of the phosphor is coated with a barrier layer. In the manufacture of high contrast cathode ray tubes for color television receivers it is known to coat the phosphor with pigments.
For improving the image in screen image tubes for color television receivers it is furthermore known to suppress undesired emissions of the phosphor by pigment coating. Concerning this reference can be made for example to German Offenlegungsschrift No. 2754369 and U.S. Pat. No. 4,152,483.
It is also known for example from British Patent Specification No. 1,484,471 to broaden the excitation region of a luminophore by combination with a second luminophore.
In German Offenlegungsschrift No. 2102120 the coating of luminophores with dielectric multiple coatings in order to suppress a part of the emission and simultaneously to increase the intensity of other emissions is described.
In German Offenlegungsschrift No. 1599011 it has already been suggested to cover luminophores which are used for rendering identity cards and the like secure with a foil in order to avoid the security feature being detectable by the naked eye.
Finally it is known from British Patent Specification No. 1,186,253 to cover indicia of luminescing substances partly with dyestuffs impermeable to the emission radiation in order to be able to show up particular indicia such as letters.
Luminophores with characteristic properties which make them suitable for rendering security papers secure for automatic authenticity detection are accordingly restricted in number. This is particularly the case with rare earth metal luminophores which are preferred in use for rendering security papers secure. Most other inorganic and organic luminophores have unc
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Kaule Wittich
Schwenk Gerhard
Stenzel Gerhard
GAO Gesellschaft Fur Automation Und Organisation mbH.
Ives P.
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