Classifications

• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
  • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
  • G07D7/06—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using wave or particle radiation
  • G07D7/12—Visible light, infrared or ultraviolet radiation
  • G07D7/1205—Testing spectral properties

Definitions

• the invention relates to a document of value, which is provided with luminescent substances to increase the security against forgery, and a method for its production.
• the object of the invention is to name another possibility with which the emission of luminescent substances can be changed characteristically in order to give a document of value a high level of security against forgery.
• the document of value has at least one pair of luminescent substances assigned to one another with a first and a second luminescent substance, which emit in a common emission range lying outside the visible spectral range.
• the invention is based on the knowledge that the combination of two luminescent substances with mutually complementary overlapping emission spectra enables a high-quality and highly reliable change, since spectral resolution of the mutually complementary luminescent emissions is only possible with great technical effort.
• the sum signal of all luminescence emissions in the spectral range under consideration is recorded. It is very difficult to draw conclusions on the chemical components of the luminescent substances on the basis of this sum signal, since the emission behavior of the lurninescent substances results not only from the substance properties but also from the respective quantitative ratios. Individual substances can therefore only be assigned to a measured emission spectrum if at least some of the luminescence peaks can be distinguished and individual substances can be clearly assigned.
• the solution according to the invention enables a large number of possible safeguards and codes.
• a high density of information is also achieved when encoded information is inserted or inserted into or into a document of value.
• the common emission range of the two luminescent substances extends from approximately 750 nm to approximately 2500 nm, preferably from approximately 800 nm to approximately 2200 nm, particularly preferably from approximately 1000 nm to approximately 1700 nm. Is the relevant luminescent emission of a luminescent substance in the Range above about 1000 nm, so it is removed from the comparatively simple detection by commercially available infrared detectors based on silicon.
• the first and / or second luminescent substance is formed on the basis of a doped host lattice.
• These luminescent substances can be excited, for example, by irradiating directly into the absorption bands of the luminescent ions and then emitting them.
• absorbing host gratings or so-called “sensitizers” can also be used, which absorb the excitation radiation and transmit it to the luminescent ion, which then emits itself with its characteristic wavelengths. It goes without saying that the host gratings and / or the dopants for the two luminescent Substances can be different in order to obtain different excitation and / or emission areas.
• the host lattice absorbs up to approximately 1.1 ⁇ m in the visible spectral range and optionally also in the near infrared range.
• the excitation can then take place via light sources, such as halogen lamps, flash lamps, LEDs, lasers or xenon arc lamps, with high effectiveness, so that only small amounts of the luminescent substance are required. This makes it possible, for example, to apply the luminescent substances to the value document using customary printing processes.
• the small amount of substance also makes it difficult for potential counterfeiters to prove the substance used. If the host lattice absorbs in the near infrared up to about 1100 nm, easily detectable emission lines of the dopant ions can be suppressed, so that only the more complex emission to detect at longer wavelengths remains.
• luminescent substances are used which absorb even in the visible spectral range, preferably over the largest part of the visible spectral range, particularly preferably into the near infrared range. Even then, emissions in these more accessible spectral ranges are suppressed.
• the first and / or second luminescent substance is a luminescent substance based on a host lattice doped with rare earth elements. Neodymium, erbium, holmium, thulium, ytterbium, praseodymium, dysprosium or a combination of these elements are particularly suitable as dopants.
• the first and / or second luminescent substance is a luminescent substance based on a host lattice doped with a chromophore, the chromophore from the group consisting of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, Copper and zinc is selected.
• a host lattice doped with a chromophore the chromophore from the group consisting of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, Copper and zinc is selected.
• the dopants and host lattices mentioned in WO 02/070279 are also suitable for use as luminescent substances in documents of value according to the invention.
• At least one of the host lattices can be doped with several chromophores. It goes without saying that the two variants can be combined, that is to say that one of the luminescent substances is based on a rare earth-doped host lattice and the other luminescent substance is formed on the basis of a host lattice with a chromophore.
• the host lattice can have a perovskite structure or a garnet structure, for example. At least one of the host lattices can also be formed by a mixed crystal. Further possible configurations of the host lattice and the dopants are listed in EP-B-0 052624 or EP-B-0053124, the disclosures of which are included in the present application.
• the first and second luminescent substances are formed on the basis of different host lattices, which have a differently strong crystal field and which are each doped with the same dopant. Due to the influence of the crystal field at the location of the dopant, its electronic levels are shifted compared to the undisturbed state. Since the size of the shift varies for the different levels, depending on the strength and symmetry of the crystal field, there are shifts in the energy distance between the electronic levels and thus also the position of the emission lines. If the same dopant is selected for the first and second luminescent substances, small shifts of the associated emission lines with respect to the undisturbed emission can be set in a controlled manner by suitable selection of host lattices with differently strong crystal fields.
• the subarea mentioned, in which the lurescence spectra of the first and second luminescent substances additionally overlap, preferably has a width of 200 nm or less, preferably 100 nm or less. In a preferred embodiment, the partial range extends from approximately 850 nm to approximately 970 nm.
• the partial range extends from approximately 920 nm to approximately 1060 nm, or from approximately 1040 nm to approximately 1140 nm, or from approximately 1100 nm to approximately 1400 nm, preferably from approximately 1100 nm to approximately 1250 nm, particularly preferably from approximately 1120 nm to approximately 1220 nm, or from approximately 1300 nm to approximately 1500 nm, or from approximately 1400 nm to approximately 1700 nm.
• the first and the second luminescent substance preferably each have at least one emission line in the partial area mentioned, the positions of which are at a distance of approximately 50 nm or less, preferably approximately 30 nm or less, particularly preferably approximately 20 nm or less, very particularly preferably have about 10 nm or less.
• the emission lines are narrow-band and in particular have a half width of about 50 nm or less, preferably about 30 nm or less, particularly preferably about 20 nm or less, very particularly preferably about 10 nm or less.
• the coding contains a further luminescent substance which has at least one emission line outside the sub-area mentioned.
• the emission line is preferably outside the visible spectral range, in particular in the infrared spectral range above 1100 nm
• Spectral range the wavelength range from 750 nm and larger, preferably 800 nm and larger.
• the document of value can also contain several pairs of luminescent substances assigned to one another, which can each be formed as described.
• the pairs of luminescent substances are preferably matched to one another in such a way that the subregions in which the emission spectra of the two luminescent substances additionally overlap are different for different pairs.
• At least one of the luminescent substances can also be printed on the value document.
• Several of the luminescent substances for example a pair of luminescent substances assigned to one another, can also be printed together in one printing ink on the value document.
• the printing inks used for this can be transparent or contain additional color pigments which must not impair the detection of the feature substances.
• they preferably have transparent regions in the excitation and considered emission region of the luminescent substances.
• the value document preferably comprises a substrate, which is printed or printed by a printed or unprinted cotton fiber, a cotton / synthetic fiber paper, a cellulose-containing paper or a coated or unprinted plastic film is formed.
• a laminated multilayer substrate can also be used.
• the documents of value according to the invention are preferably banknotes, shares, credit cards, identity or identity cards, passports of any kind, visas, vouchers etc.
• One or more of the luminescent substances e can also be introduced into the volume of the value document, in particular the value document substrate.
• the luminescent substances can be introduced into the volume of a paper substrate, for example, by a method as described in EP-A-0659935 and DE 101 20818. To this extent, the disclosures of the cited documents are included in the present application.
• the invention also makes it possible to use the number of luminescent substances used to generate codes which are also difficult to imitate and thus to be falsified.
• two luminescent substances that are used are used According to the invention, if they overlap in a partial area of the spectrum, at least three codings can be generated via the presence or absence of the individual luminescent substances Supplement according to the invention in different sub-areas of the spectrum, used to form such encodings.
• Another variant for generating encodings is to provide the pair or pairs of mutually associated luminescent substances in geometrically arranged areas on or in the value document. A single area can also represent a coding.
• the coding can then consist of a certain luminescent substance pair being present from a number of possible pairs in this area of the value document.
• the coding represents information about the document of value, the information being present in encrypted or unencrypted form.
• the denomination of a banknote can be coded in a single field of the note if, depending on the denomination, a predetermined pair of luminescent substances is provided there.
• Variations and combinations of the different dopants and host lattices can be used to generate a large number of luminescent substance pairs, the emission lines of which are relevant for the coding, and which additionally overlap in different spectral subregions.
• very compact codes can be formed which, with a high density of information, take up little space on the value document.
• At least one of the luminescent substances can already be added to the document of value during paper production.
• at least one of the luminescent substances can be added to a printing ink and applied to the value document with the printing ink.
• a printing ink For example, gravure, screen printing, letterpress, flexographic, inkjet, digital, transfer or offset printing can be used as the printing process.
• At least one of the luminescent substances e can also be applied to the value document by means of a coating process.
• At least one of the luminescent substances is supplied to the document of value through appropriately prepared mottled fibers during paper manufacture.
• at least one of the luminescent substances is fed through a correspondingly prepared security thread or security strip during paper manufacture.
• a correspondingly prepared self-supporting transfer element such as a patch or label, which is applied, in particular glued, to the value document, can also be used to apply at least one of the luminescent substances.
• the luminescent substances of a pair assigned to one another are preferably supplied to the value document using the same method in order not to facilitate analysis by spatially separating the assigned luminescent substances.
• different pairs of luminescent substances can be supplied using different methods. For example, a first pair of luminescent substances can be introduced into the paper substrate of a banknote during paper production and a second pair of luminescent substances can be printed on the banknote.
• a transfer element such as a hologram patch, can be provided with a third pair of luminescent substances and can be glued to the bank note as a further security feature.
• Show it: 1 is a schematic representation of a banknote with a coding according to an embodiment of the invention
• Fig. 2 shows a section through the banknote of Fig. 1 along the line II-II, and
• FIGS. 1 and 2 show schematic emission profiles of various luminescent substances, as can be used in the coding of FIGS. 1 and 2.
• FIG. 1 and 2 show a schematic illustration of a bank note 10, in which a code 11 is printed on the paper substrate 20 of the bank note.
• 1 shows the bank note 10 in a top view and
• FIG. 2 shows a cross section along the line II-II of FIG. 1.
• the coding 11 contains two pairs of luminescent substances 12, 13 and 14, 15 assigned to one another.
• the luminescent substances 12-15 show emissions in the infrared spectral range between 1000 and 1500 nm, whereby the emission spectra of two mutually associated luminescent substances additionally overlap in a specific sub-region of this spectral region, as described in more detail below.
• any information for example the design Store the nomination and currency of the banknote 10 or a serial number in the code 11.
• the coding shown can be used, for example, to represent a ternary code in which the state “0” is represented by an area without luminescent substances, the state “1” is represented by an area with the first pair of luminescent substances 12, 13 and the state “2” is represented by an area with the is represented by a second pair of luminescent substances 14, 15.
• a measurement of the coding 11 shown in FIG. 1 with a suitable detector would therefore recognize the secondary coding “12021102”. This provides a compact coding that combines a high level of security against forgery with a high density of information and a small footprint.
• the luminescent substances 12 and 13 are each formed on the basis of a neodymium-doped host lattice and, as shown in the left part of FIG. 3, each have an emission line in the range around 1064 nm. However, the two luminescent substances 12, 13 are formed on the basis of different host lattices, which generate a differently strong crystal field at the location of the neodymium ion.
• the interaction between the crystal field and the neodymions results in emission lines 22 and 23 which are shifted slightly for the undisturbed value for both luminescent substances.
• the peak position of the luminescent curve 22 of the first luminescent substance 12 is at a wavelength of 1065 nm and the
• the two luminescence spectra 22, 23 overlap one another in the partial range from approximately 1000 nm to approximately 1150 nm in such a way that the emission spectrum 22 of the first luminescent substance 12 is supplemented by the emission spectrum 23 of the second luminescent substance 13.
• the presence of the two luminescent substances 12 and 13 can practically not be recognized without prior knowledge of the substances used from the enveloping emission curve, so that the coding 11 has a high level of security against forgery. Since the spectrum is generated by different matrices in which the luminescent ions are located in different crystal fields, there are also no matrices that show the same emission spectrum by themselves.
• the middle part of FIG. 3 shows the emission curve 24 and 25 of the luminescent substances 14 and 15 of the second pair of luminescent substances in the subrange relevant to them at wavelengths of 1150 to 1250 nm.
• the luminescent substances 14, 15 are each based on a formed with a chromophore doped host lattice, the chromophore being selected from the group scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc.
• the envelope of the luminescent emissions of the two luminescent substances 14, 15 practically cannot be deduced from the type of luminescent substances used without further information.
• the luminescence emission of the aforementioned luminescent substances 12 and 13 at a wavelength of approximately 1300 nm is shown in the right-hand part of FIG. 3.
• the coding 11 can also contain a further luminescent substance which, after excitation, shows an emission at a wavelength above 1100 nm. Its emission wavelength is tuned in such a way that it does not fall into the overlapping areas of the first or second pair of luminescent substances.
• the presence or absence of the further luminescent substance in certain areas can also be used for coding and thus further increases the number of coding possibilities.

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• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Physics & Mathematics (AREA)
• Credit Cards Or The Like (AREA)
• Inspection Of Paper Currency And Valuable Securities (AREA)
• Luminescent Compositions (AREA)
• Printing Methods (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2003
  • 2003-10-08 DE DE10346688A patent/DE10346688A1/de not_active Ceased
• 2004
  • 2004-10-05 EP EP04790135A patent/EP1673739A2/de not_active Withdrawn
  • 2004-10-05 CN CN2004800297775A patent/CN1867947B/zh active Active
  • 2004-10-05 US US10/574,663 patent/US20080252065A1/en not_active Abandoned
  • 2004-10-05 WO PCT/EP2004/011132 patent/WO2005036479A2/de active Application Filing
  • 2004-10-05 RU RU2006115176/09A patent/RU2368013C2/ru active
• 2006
  • 2006-04-04 TN TNP2006000098A patent/TNSN06098A1/en unknown
  • 2006-04-04 MA MA28915A patent/MA28138A1/fr unknown

Non-Patent Citations (1)

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