RU2793581C2 - Valuable document system - Google Patents

Abstract

FIELD: valuable document system.

SUBSTANCE: present invention relates to a valuable document system, a method for identifying a valuable document in a valuable document system, and a set of luminescent materials. The valuable document system includes at least the first valuable document and the second valuable document. The first valuable document has a security feature in form of a combination of at least one first and one second luminescent material of the first or second class of substances. The second valuable document has a security feature with at least one first luminescent material from the first or from the second class of substances. The security feature of the first valuable document has, compared to the security feature of the second document of value, at least a different ratio of emission intensities, a different ratio of decay periods and/or a different sum of decay periods in two adjacent spectral bands.

EFFECT: increasing the degree of security of valuable documents without the need for a significant increase in the complexity of manufacturing the sensors necessary for authentication.

19 cl, 7 dwg

Description

The present invention relates to a value document system that includes at least a first value document and a second value document, a method for identifying a value document of the value document system, and a set of luminescent materials for manufacturing the value document system.

Documents of value are understood to mean objects made in the form of a sheet, which represent, for example, a monetary value or a certificate of title, and which therefore cannot be produced arbitrarily by an unauthorized person. Therefore, they have hard-to-reproduce, primarily replicable, security features, the presence of which is evidence of their authenticity, that is, their manufacture by an authorized authority. Important examples of such documents of value are electronic chip cards, coupons, vouchers, cheques, and above all banknotes, stocks, vouchers, identity cards, credit cards and passports, as well as labels, seals, packaging or other items for the protection of value.

As a rule, valuable documents are protected by special marking against unwanted and, in some cases, illegal reproduction. It has long been known to equip valuable documents for this purpose with luminescent materials which have a specific emission characteristic. First of all, it is known to use security features in the form of a combination of different luminescent materials, as well as to detect and process data on the luminescence decay period for checking documents of value.

In principle, systems of value documents are known in which documents of value are divided into different classes and distinguished from one another by means of various security features. In principle, security features are also known based on two or more luminescent materials with partially overlapping emission or excitation spectra. For example, EP 2 512 821 B1 shows valuable documents with mixtures of substances from sulfoxides, phosphates and vanadates, and EP 2 271 504 B1 shows mixtures of substances.

For example, in value document systems according to the prior art, for the most part, several different luminescent materials with correspondingly different emission spectra are used. In this case, luminescent materials mean individual materials that consist of a doped matrix and exhibit, depending on the composition of the matrix, different emission spectra. The emission spectrum is detected by means of a sensor with several spectral channels, and from it a conclusion is made about the class of substances used. The division into different classes of value documents is then carried out by isolating these classes of substances, optionally by using the observed luminescence decay periods.

Documents of the prior art demonstrate the ability to authenticate documents of value and to protect them. When checking, the presence of the corresponding security feature is checked and, based on the results of the check, a conclusion is made about the authenticity of the valuable document.

Accordingly, it is an object of the invention to increase the security of documents of value, in particular without having to substantially increase the complexity or cost of manufacturing the sensors required for authentication.

The goal is achieved by means of a system of valuable documents, a method for identifying valuable documents and a set of luminescent materials according to the independent claims. The most preferred embodiments are the subject of the dependent claims.

The value document system according to the invention has at least two value documents, namely at least a first value document and a second value document.

The first value document has a security feature in the form of a combination of at least one first and one second luminescent material. The first luminescent material of the security feature of the first document of value is a luminescent material of the first substance class, and the second luminescent material of the first value document is a luminescent material of the second substance class. In addition, the first and second luminescent materials of the security feature of the first document of value have partially overlapping emission spectra. The first and second luminescent materials of the security feature of the first document of value furthermore have a decay period of less than 5 ms.

The second document of value has a security feature with at least one first luminescent material. The first luminescent material of the second document of value belongs to the first substance class or the second substance class. The decay period of the first luminescent material of the second document of value is maximum 5 ms.

The first and second luminescent materials of the security feature of the first document of value are designed in such a way that their emission spectra partially overlap, and the primary emission range formed by the overlapping emission spectra is separable into two different, directly adjacent spectral ranges. In this case, two adjacent spectral ranges, namely the first spectral range A (from λ _A1 to λ _A2 ) and the second spectral range B (from λ _B1 to λ _B2 ), respectively, exceed 50 nm and are less than 500 nm, and at least one from two adjacent spectral ranges includes at least part of the emission of the first and second luminescent materials of the security feature of the first document of value.

эмиссии защитного признака второго ценного документа в спектральных диапазонах А и В столь же велика, как общая интенсивность

эмиссии защитного признака первого ценного документа, то есть

The emission of the security feature of the second value document is at least partially located, in other words at least 1% of its intensity, in at least one of the adjacent spectral bands A, B. Preferably, the total intensity

emission of the security feature of the second valuable document in the spectral ranges A and B is as large as the total intensity

issue of the security feature of the first document of value, i.e.

,

,

и

dx, причем

или же

является эмиссионным спектром первого или же второго ценного документа. В предпочтительном варианте осуществления

,

,

и

относятся к заданному, прежде всего одинаковому, моменту измерения. Защитный признак второго ценного документа имеет по сравнению с защитным признаком первого ценного документа отличное отношение интенсивностей эмиссии, отличное отношение периодов затухания и/или отличную сумму периодов затухания в спектральных диапазонах А, В. Отличному отношению интенсивностей эмиссии, отличному отношению периодов затухания и или отличной сумме периодов затухания в спектральных диапазонах А, В первого и второго ценных документов соотнесено кодирование защитного признака и/или распознавание ценных документов первого и/или второго ценных документов. При этом является действительным:Wherein

,

,

And

dx, and

or

is the emission spectrum of the first or second document of value. In the preferred embodiment

,

,

And

refer to a given, primarily identical, moment of measurement. The security feature of the second document of value has, compared to the security feature of the first document of value, a different emission intensity ratio, a different decay period ratio and/or a different sum of decay periods in the spectral bands A, B. attenuation periods in the spectral bands A, B of the first and second documents of value, the coding of the security feature and/or recognition of the documents of value of the first and/or second documents of value is correlated. In this case, it is valid:

The ratio of the emission intensities of the security feature of the first or second valuable document is a quotient of the total intensity of the respective luminescent materials in the spectral ranges A and B:

The ratio of the attenuation period V of the security feature of the first or second value document is a quotient of the corresponding total periods τ _A or τ _B of attenuation in the spectral bands A and B:

In this case, τ _A is a measure for the decay period I _A , and τ _B is a measure for the decay period I _B . To detect τ _A or τ _B , for example, a quotient of I _A or I _B can be detected at two points in time, a mathematical function is selected for the course of the process in time for I _A or I _B or it can be found to which point in time I _A whether I _B falls below a predetermined threshold value.

The sum S of the decay periods is the sum of the total decay periods τ _A or τ _B in the two spectral ranges A and B of the security feature of the first and/or, if appropriate, of the second document of value:

The various security features of the value document system are distinguished by the ratio U of their intensities and/or the ratio V of their decay periods and/or their sum S of the decay periods.

The first class of substances includes luminescent materials with a doped garnet structure, primarily yttrium aluminum garnet (YAG), lutetium aluminum garnet (LuAG), gadolinium gallium garnet (GGG), gadolinium scandium gallium garnet (GSGG), yttrium - scandium gallium garnet (YSGG), calcium niobium gallium garnet (CNGG), gadolinium scandium aluminum garnet (GSAG), calcium lithium niobium gallium garnet (CLNGG), transition metal containing garnet structures such as, for example yttrium iron garnet (YIG) or other variants or mixed embodiments of such garnet structures. The second class of materials includes luminescent materials doped with rare earth sulfoxide, doped with rare earth phosphate, or doped with rare earth vanadate.

Rare earth phosphates are expressly understood to mean the orthophosphate of one or more trivalent rare earth cations X, i.e. XPO ₄ , in contrast to other phosphates used in the prior art as a matrix for luminescent materials, such as, for example, pyrophosphates, polyphosphates of the X(PO ₃ ) _{3 type} , ultraphosphates such as XP ₅ O ₁₄ , and other other phosphates.

Equally, similarly, rare earth vanadates are explicitly understood to mean orthovanadates of one or more trivalent rare earth cations X, ie XVO ₄ .

Suitable rare earth sulfoxides are, for example, lanthanum sulfoxides, yttrium sulfoxides, gadolinium sulfoxides, lutetium sulfoxides or mixed sulfoxides based on them. Suitable rare earth phosphates are, for example, lanthanum phosphates, yttrium phosphates, gadolinium phosphates, lutetium phosphates or mixed phosphates based on them. Suitable rare earth vanadates are, for example, lanthanum vanadates, yttrium vanadates, gadolinium vanadates, lutetium vanadates or mixed vanadates based on them.

Numerous matrices for inorganic luminescent materials are known in the prior art. For example, oxides, especially 3- and 4-valent oxides, such as, for example, titanium oxide, aluminum oxide, iron oxide, boron oxide, yttrium oxide, cerium oxide, zirconium oxide, bismuth oxide, as well as more complex oxides such as such as perovskites, inter alia, yttrium-aluminum perovskite, lanthanum-gallium perovskite; spinels, inter alia, zinc-aluminum spinel, magnesium-aluminum spinel, manganese-iron spinel; or mixed oxides such as, for example, ITO (indium tin oxide);

halogen oxides and oxychalcogenides, especially oxychlorides, such as, for example, yttrium oxychloride, lanthanum oxychloride; sulfides and other chalcogenides, for example zinc sulfide, cadmium sulfide, zinc selenide, cadmium selenide; sulfates, especially barium sulfate and strontium sulfate;

alkaline earth metal phosphates, in particular barium phosphate, strontium phosphate, calcium phosphate, as well as more complex phosphate-based compounds such as, for example, apatites, among others, calcium hydroxyl apatites, calcium fluoride apatites, calcium chloride apatites; or spodiositis, including, for example, calcium-fluoro-spodiositis, calcium-chlorine-spodiositis; silicates and aluminosilicates, especially zeolites, such as, for example, zeolite A, zeolite Y; zeolite-like compounds such as, for example, sodalites; feldspars such as, for example, alkali feldspars, plagioclases;

other classes of inorganic compounds such as, for example, germanates, arsenates, niobates, tantalates, tungstates or aluminates.

However, no system of value documents according to the invention with the said advantageous properties can be produced with these materials. This is only possible by selecting the aforementioned special classes of substances with additional spectral properties, as described below.

Thus, arbitrary luminescent materials cannot be combined with one another in order to construct the system of value documents according to the invention. On the contrary, within the scope of the invention, a purposeful choice is necessary which allows complementary spectral properties to be appropriately combined in such a way that several suitable encodings can be formed. Complementary spectral properties mean that different luminescent materials can be distinguished due to their different spectral properties. This means, for example, that directly or directly adjacent intensity maxima of different luminescent materials, when measured by sensors with a resolution of >50 nm, differ significantly from each other by more than 50 nm.

For inorganic luminescent materials, according to the prior art, numerous dopants are known, for example rare earths: Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, as well as other dopants Bi, Pb , Ni, Sn, Sb, W, TI, Ag, Cu, Zn, Ti, Mn, Cr and V (or their ions). In this case, the alloying materials can be used individually or in combination (for example, as an additional alloying material).

Luminescent materials according to the invention require at least one doping material from the group Nd, Yb, Er, Tm, Ho. Preferably, the luminescent materials contain at least ytterbium or neodymium or erbium as a dopant, particularly preferably ytterbium or neodymium, since in this case particularly good detectability can be obtained by means of a simple detector design due to the emission wavelength range. Preferably, in addition to the alloying material from the group Nd, Yb, Er, Tm, Ho, other (optional) alloying materials are still available. In this case, doping materials from the group Nd, Yb, Er, Tm, Ho act as emission centers for the luminescent materials described here. Preferably, the emission centers of the luminescent materials are Nd, Yb or Er, particularly preferably Nd or Yb. The term "emission center" here means that the emission of the luminescent material comes from this dopant material. For example, in a typical neodymium (Nd) to ytterbium (Yb) energy transfer, when the neodymium is excited, the ytterbium forms an emission center, since in this case the neodymium emission is suppressed by the energy transfer. Equally, for example, in the case of an erbium-doped matrix, in which praseodymium is added as an additional doping material to control the decay period, while without self-luminescence, the emission center forms a luminescent emitting erbium.

The security features according to the invention of the first value document are therefore a mixture of substances from at least one luminescent material from a first substance class and at least one luminescent material from a second substance class, as described in the following.

In one embodiment, the security feature of the first and/or, if necessary, the second document of value may mean a mixture of luminescent materials of the first and/or second class of substances, and additionally other luminescent materials may be present that do not belong to either the first or the second. class of substances. In this way, for example, the spectral configuration of the emission spectrum can be fine-tuned or the number of codings can be further increased.

Preferably, the luminescent materials essentially do not exhibit (<5% relative intensity) any additional anti-Stokes emission. In this way, inter alia, the ability to achieve the visibility of the security feature by means of an infrared laser pointer or similar upconversion detection devices is prevented.

By combining at least one first and one second luminescent material in the security feature of the first and optionally the second value document, a large number of codings can be made. Based on the generated coding, the security feature can be assigned to a class of document of value, such as denomination and/or value. In other words, not only the presence of a predetermined security feature on the value document can be checked, but also the compliance of the value document with an encoding or class of value documents that can be identified and correlated by the recognized security feature.

The recognition of documents of value or the coding of the security feature of the first and second documents of value can be related to the denomination of the banknote and/or the country of origin, or also testify to the authenticity of the first or second document of value, especially in combination with other information.

The security feature of the first value document is understood to mean at least the first and second luminescent materials in a detectable or in a detectable quantitative ratio in combination (preferably in the form of a mixture). This means that the first and second luminescent materials of the first document of value are present in a detectable or detectable relative proportion with respect to the total amount of luminescent materials in the security feature. Thus, the security feature can be identified in an unambiguous way.

At least the first and second luminescent materials of the first value document and at least the first luminescent material of the second value document can be placed in different ways on or in the first or second value documents. They can be admixed, for example, with the paper or polymer pulp for producing the first or second document of value, or with the printing ink for printing the first or second document of value. It is also contemplated that the first and/or second luminescent material of the first document of value or at least the first luminescent material of the second document of value may be provided in the form of, for example, an invisible coating on the document of value. The first and second luminescent materials of the first document of value and/or at least the first luminescent material of the second document of value may also be provided on or in a carrier material consisting of, for example, a polymer, which material is incorporated into the paper or polymer mass to produce a valuable document. The carrier material may, for example, be in the form of a security or identification thread, mottled fibers or confetti. The carrier material can also be placed, for example in the form of a plaque, on the document of value, for example in order to take measures to protect the product. In principle, an arbitrary shape of the carrier material is possible.

перекрытия, ср. фиг. 1А). При этом оба эмиссионных спектра первого и второго люминесцентных материалов первого ценного документа перекрываются частично, но не полностью. Первый или же второй люминесцентный материал первого ценного документа участвует в общей интенсивности защитного признака в области

перекрытия интенсивностью испускаемого им люминесцентного излучения в зависимости от его относительной пропорции. Термин «общая интенсивность» всегда относится к суммарной интенсивности, возбужденных посредством одного (того же) возбуждающего импульса и регистрируемых в тот же момент времени на заданной длине волн или в заданном диапазоне длин волн люминесцентных излучений содержащихся в комбинации в защитном признаке люминесцентных материалов. Соответствующим образом термин «общий период затухания» относится к периоду затухания общей интенсивности, в отличие от индивидуального периода затухания индивидуальной интенсивности люминесцентного материала.At least the first and second luminescent materials of the first value document and at least the first luminescent material of the second value document have emission spectra of separate materials. The first and second luminescent materials of the first document of value have different emission spectra of the individual materials which overlap in the wavelength range (hereinafter referred to as the area

overlap, cf. fig. 1A). In this case, both emission spectra of the first and second luminescent materials of the first document of value overlap partially, but not completely. The first or second luminescent material of the first document of value contributes to the overall intensity of the security feature in the area

overlap by the intensity of the luminescent radiation emitted by it, depending on its relative proportion. The term "total intensity" always refers to the total intensity of the luminescent radiations of the luminescent materials contained in combination in the security feature, which are excited by the same (same) excitation pulse and recorded at the same time at a given wavelength or in a given wavelength range. Accordingly, the term "total decay period" refers to the decay period of the overall intensity, as opposed to the individual decay period of the individual intensity of the luminescent material.

The terms "integral total intensity" and "integral individual intensity" refer to the spectral integral of the corresponding intensity over a given area.

By measuring the total intensity at a typical resolution, preferably 20 nm, a continuous "primary emission range" (PEB) can be obtained, which is defined as follows (see Fig. 1B, the range between the dotted lines):

- the maximum of the total intensity is in the primary emission range.

- the primary emission range is the largest coherent wavelength range in which the total intensity does not fall below 10% of the maximum.

Such a determination is based on the fact that, in order to effectively and quickly read the security feature, the main emission must necessarily be evaluated, and not exclusively, for example, possibly also a weaker side emission. In addition, the detection of the decay period in less intense ranges leads to higher measurement inaccuracies or to an increase in the signal-to-noise ratio, so that for these partial ranges, no value for the decay period can be reliably detected with a fast measurement.

The "degree of overlap" of the two emission spectra of individual materials for two different luminescent materials in the primary emission range is given as follows:

First, the emission spectra of individual materials I' (x) and J' (x), the curves of which are obtained by correlating the individual intensities I' or J' with the wavelength (x), are normalized to an equal area. That is:

In this case, normalization is given, for example, by unit area. λ1 is the lower limit wavelength of the primary emission range, λ2 is the upper limit wavelength of the primary emission range.

The degree of overlap is then given by the following formula:

It denotes the relative component of the spectral overlap within the primary emission range between the emission spectra of the individual materials of the respective luminescent materials.

The degree of overlap of the emission spectra of two luminescent materials is a parameter independent of the relative intensity and proportion of the luminescent materials, which only refers to the shape-dependent overlap of the respective emission spectra of the individual materials. To detect the degree of overlap, emission spectra measured at room temperature are used, which are measured with a typical sensor resolution, preferably 20 nm.

According to the invention, the first and second luminescent materials of the first document of value are designed in such a way that their emission spectra of the individual materials have an overlap of less than 80%, preferably less than 65%, particularly preferably less than 50%, and an overlap of more than 5%, preferably more than 10%. , particularly preferably more than 20%.

Value document systems which comprise security features of such luminescent materials overlapping their emissions can have the most preferred properties for a given combination of luminescent materials. Surprisingly, it has been found that, by means of a specific combination of a first luminescent material and a second luminescent material, it is possible to develop systems from a mixture of materials that have advantageous properties, especially the additional emission spectra of the first and second substance classes, when combined, produce a high number of well-separable encodings simultaneously. with high security against counterfeiting. These encodings can also be reliably distinguished by sensors that do not work with multiple high spectral resolution spectral channels and therefore have less significant complexity.

For value document systems according to the invention, instead of several different individual luminescent materials with correspondingly different emission spectra, mixtures of substances from luminescent materials overlapping in their emissions can be used. Thus, depending on the choice of material for the first and second luminescent materials and their quantitative ratio, several emission spectra can be produced which, for example, are similar to those of the respective individual materials, or also different from those of the individual materials and have different properties.

By using at least two different luminescent materials, namely the first and second luminescent materials of the first value document, it is possible, taking into account different mixture ratios in the security feature, to produce several security features. This makes it possible to make better use of scale effects in production, since the first and second luminescent materials of the first value document, which can be contained in this case in all mixtures, are required in general in noticeably larger quantities than when the corresponding encodings are formed with using several separate luminescent materials.

Another advantage can be derived from the fact that materials with a specific emission spectrum are often only available through the selection of exotic matrices. By "exotic" here is meant matrices with unusual structures, such as those that have been academically proven to exist, but which are nonetheless difficult to produce and therefore not suitable for commercial use. For example, the manufacture of such matrices requires unusual reaction conditions, expensive starting materials, or multiple synthetic steps. Although such materials may have unusual and unique emission spectra, their other properties, such as, for example, low chemical resistance to acids or alkalis, are often not suitable for use as a security feature.

If the emission spectrum of the security feature of the first document of value according to the invention is composed of the emission spectra of the individual materials of the first and second luminescent materials, materials with the most preferred properties can be used in a targeted manner. Such properties include, among others, high chemical resistance, high luminescence efficiency, ease of synthesis, and inexpensive raw materials. Equally, new emission spectra can be generated that do not match the known individual material. First of all, the emission spectra can be purposefully adapted to achieve, for example, the best possible separability of the different codings.

A third advantage can be obtained by combining the properties of materials that overlap in their emissions, resulting in emission spectra with new types of temporal properties that are not available with separate materials. These include, for example, mixtures of materials with different decay periods, in which the detected emission spectrum changes with time in a given way.

An embodiment can provide that at least two, preferably at least three, security features of the value document system are formed in such a way that they respectively show different emission spectra immediately after excitation, however, respectively, at different time periods after excitation show the same same emission spectrum. This is achieved by a suitable combination of the first and second luminescent materials of the security feature, respectively, with different decay periods in the spectral ranges A or B. In this case, the individual security features can be distinguished from each other by setting an appropriate time period after excitation, after which the pre-assigned target spectrum is reached.

The advantages of the invention can be particularly well disclosed in the machine measurement of documents of value in high-speed sensors and in the context of suitable methods, in contrast to the method used, for example, in the forensic examination of a single banknote in a laboratory. In this case, banknotes are usually moved through the machine at speeds of up to 12 meters per second, in such a way that particularly high demands are placed on detection methods and material properties. In addition, with the security features according to the invention, it is possible to distinguish between the individual codings of a valuable document system with a simple sensor that covers, for example, the primary emission range with only two or only three detection channels.

In one embodiment, the security feature of the second value document includes a second luminescent material, wherein the first luminescent material of the second value document belongs to a first substance class and the second luminescent material of the second value document belongs to a second substance class. The first luminescent material and the second luminescent material of the second document of value have partially overlapping emission spectra. In addition, the first and second luminescent materials of the security feature of the second document of value are designed in such a way that their primary emission range of partially overlapping emission spectra is separable into at least two different directly adjacent spectral ranges A, B, with at least two adjacent spectral ranges exceed 50 nm and are less than 250 nm, and moreover, at least one of at least two adjacent spectral ranges includes at least part of the emission of the first and second luminescent materials of the security feature of the second document of value (i.e., the percentage component of the integral over the emission range, which is located within the spectral sensitivity band of the respective detection channels, is greater than zero), and moreover, the spectral ranges A, B of the security feature of the second valuable document are identical to those of the security feature of the first valuable document.

In this embodiment, both the security feature of the first and the security feature of the second document of value consist of mixtures of substances from materials of the first and second classes of substances with partially overlapping emission spectra. In this way, inter alia, the security against forgery can be further increased and the security feature of the second document of value also receives the already described advantages of such mixtures of substances compared to the use of single materials. For example, it is possible to produce new emission spectra that do not correspond to a known single material. Another advantage can be obtained by combining the properties of materials that overlap in their emissions, resulting in emission spectra with new types of temporal properties that are not available with separate materials.

In a preferred embodiment, at least two, preferably at least three, particularly preferably at least four, value documents of the value document system have a security feature that consists of a mixture of luminescent material substances of a first class of substances and a second class of substances with partially overlapping emission spectra .

Similar to the security feature of the first document of value with the first and second luminescent materials, in this case the ratio U of the emission intensities of the security feature of at least the second document of value is a quotient of the total intensity of the first and second luminescent materials of the security feature of the second document of value in the spectral ranges A, B The ratio V of the decay period of the security feature of the second document of value is the quotient of the total decay periods τ _A or τ _B in spectral bands A or B of the security feature of the second document of value, and the sum S of the decay periods of the security feature of the second document of value is the sum of the total periods τ _A and τ _B attenuation in the spectral ranges A, B of the security feature of the second document of value.

To distinguish between different security features of different value documents, value document systems preferably always use the same spectral bands A, B.

In one embodiment, respectively, the first and second luminescent materials of the security feature of the first document of value have the same decay period as the first and second luminescent materials of the security feature of the second document of value, especially all luminescent materials with overlapping emission in two spectral bands A and B, have correspondingly the same decay period. The overlapping emission luminescent materials are selected such that their decay times are substantially equal, i.e. their decay times differ from each other by less than 10%, preferably by less than 5% (relative to the shortest individual decay time of the luminescent materials ).

In this case, the emission spectrum composed of different luminescent materials manifests itself as the spectrum of a new individual material. Advantageously, in this embodiment, inter alia, in the production of security features, it is possible to adapt the spectral properties without affecting the decay period or the ratio of the decay periods in different spectral ranges. This ensures, among other things, the alignment of production deviations or the matching of the spectral properties of the security feature with the absorption bands of the substrate and the like.

In addition, the measured emission spectrum of a valuable document gives the potential counterfeiter another class of substances, which, however, does not suit the other properties of the material. Thus, the security against forgery can be improved.

Preferably, the decay period of the individual luminescent materials of the security features of the first and second value documents is at least 0.05 ms. Most preferred is the location of the decay period in the range from 0.05 to 5 ms. Within this range, good machine detectability of the decay period in banknote processing machines can be ensured. Measuring shorter decay periods is technically expensive, and detecting longer decay periods is not possible due to the high speed of banknotes, up to 12 meters per second, in banknote processing machines.

Another embodiment may provide that the first and second luminescent materials of the first document of value and, optionally, of the second document of value, differ in decay times by between 10% and 50% (relative to the shortest individual decay period of the luminescent materials). In this case, the spectrum composed of different luminescent materials looks, at first glance or in the case of surface analysis, as the spectrum of a separate material. However, a slight difference can be used to distinguish a security feature in an accurate analysis from a single material with the same emission spectrum. This achieves, inter alia, better protection against counterfeiting.

Another embodiment may provide that the first and second luminescent materials of the first value document, as well as at least one luminescent material of the second value document, differ in decay times by at least 50%, preferably by 75%, and particularly preferably by more than 100% , (relative to the shortest individual decay period of luminescent materials). As a security feature, all luminescent materials with overlapping emission therefore have, in the two spectral ranges A and B, substantially different dynamic decay characteristics, or else substantially different decay times.

In this case, especially strong protection against imitation is provided, since the dynamic attenuation characteristics in the various detection channels of the sensor are highly dependent on the selected measurement parameters (detection channel value, etc.), which must be known to a potential imitator in order to counterfeit the corresponding security feature. As another advantage, in this case, special encodings of the value document system can be produced which have the same emission spectrum, but are mutually different with respect to the decay period in spectral bands A and B, or alternatively in different detection channels of the sensor. For example, when using two detection channels, channel 1 and channel 2, which measure the emission spectrum with respectively the same intensity, the following cases may occur:

A) Channel 1 detects a longer decay period than channel 2;

B) Channel 1 and channel 2 detect the same decay period;

B) Channel 1 detects a shorter decay period than channel 2.

In this way, documents of value can be divided by means of a sensor into three or more classes, for example three different currencies, in relation to the decay period, although they exhibit exactly the same emission spectrum.

In addition, more complex forms of overlap or spectral dynamic responses are possible. For example, the luminescent material may not only consist, as schematically represented, of a symmetrical emission spectrum band formed, but also have an asymmetric band, a main band with a shelf, or several bands, such as a main band and several side bands, in the range under investigation. In addition, individual luminescent materials as such may exhibit temporal characteristics, such as measurable dynamic decay characteristics with their associated decay period, or an atypical decay curve. This makes possible a much more complex relationship between the observed spectral range and the observed decay period with local minima, local maxima or with one or more inflection points.

A specific combination of luminescent materials is necessary to simulate the continuous variation with wavelength of the change in the total decay period of such mixtures of luminescent materials, since the individual components must sum up the target spectrum not only in sum, but also in suitable areas of spectral overlap, and must have suitable decay period ratios. Thus, imitation can be significantly difficult. According to the invention, by combining at least two luminescent materials with a given degree of overlap and specific different decay times, it is possible to achieve an effective protection against spoofing. Simulation by means of a combination of different luminescent materials with different spectral properties in this case is only possible if the exact measurement parameters are known, primarily the spectral position and shape of the filter characteristics of the detection channels, the temporal course of the change in sampling or the temporal course of the luminescence change, and See also the algorithm or the chosen measurement parameters for detecting the effective decay period.

By means of an overlap of the emission spectra of the individual materials of the luminescent materials of less than 80% and more than 5%, sufficient dispersion of the decay period characteristics of the overall intensity of the luminescent materials can be ensured, and advantageously prevented, on the one hand, from having a separate, constant over the entire range, mixed decay period (respectively degree of overlap of 100%, i.e. the identical spectral shape of both emissions), and, on the other hand, the presence of separate, isolated emissions with correspondingly constant decay periods (respectively, the degree of overlap is 0%).

Preferably, the emission spectra of the individual materials of the luminescent materials, and thus the primary emission range, are located in a narrow spectral range, ie, for example, in the spectral range of less than 300 nm. In a preferred embodiment of the value document according to the invention, the luminescent materials are designed for this purpose in such a way that directly or directly adjacent intensity maxima of different emission spectra of the individual materials differ from each other by less than 200 nm, preferably by less than 100 nm. Preferably, directly or directly adjacent intensity maxima of the different emission spectra of the individual materials are separated from each other by more than 20 nm, particularly preferably by more than 50 nm, in order to obtain a sufficiently large overlap area for the first or second security feature. In a most preferred embodiment of the invention, directly or directly adjacent intensity maxima of different luminescent materials respectively have a distance from each other of less than 100 nm and more than 50 nm.

Preferably, the primary emission range of the luminescent materials is in the infrared range, ie between 700 nm and 2000 nm, particularly preferably between 800 nm and 2000 nm.

In a preferred embodiment, the luminescent materials are excited in the infrared range, ie between 700 nm and 2000 nm, preferably between 800 and 1500 nm.

In another preferred embodiment, the luminescent materials are excited in the visible spectral range, ie between 400 nm and 700 nm. In this case, excitation in the infrared range is particularly preferred.

Preferably, the emission centers of luminescent materials are rare earth ions, especially rare earth ions such as neodymium (Nd), ytterbium (Yb), erbium (Er), thulium (Tm), and/or holmium (Ho).

In one embodiment of the invention, the primary emission range of the luminescent materials is in the range from 750 nm to 1100 nm, especially in the range from 800 nm to 1100 nm. In a preferred embodiment of the invention, the primary emission range is in the range from 900 nm to 1100 nm. In these ranges, for example, neodymium and/or ytterbium luminescent materials can be used to advantage.

In one other embodiment of the invention, the primary emission range is in the range from 1500 nm to 1900 nm, preferably in the range from 1500 nm to 1700 nm. In these ranges, for example, luminescent materials with erbium and/or thulium can be used advantageously. Alternatively, the primary emission range may range from 1700 nm to 1900 nm. In these ranges, for example, luminescent materials with thulium and/or holmium can be used advantageously.

In one embodiment, the luminescent materials for the overlapped emission value document system of the invention respectively have the same rare earth ions as emission centers. Preferably, the overlapped emission luminescent materials have only one particular kind of rare earth ions from the group {Nd, Yb, Er, Tm, Ho}. For example, one of the luminescent materials, such as the first, contains only erbium and no other of the group, and the other luminescent material, such as the second luminescent material, also contains only erbium and no other of the group. This ensures, inter alia, that two different, separate value document systems do not contain, in whole or in part, the same rare earth ions and thus do not interact with each other and do not mutually interfere with each other. In addition, a situation is prevented where, by means of isolated excitation of other rare earth ions, individual components of a mixture of substances can be analyzed individually.

In a preferred embodiment, the overlapped emission luminescent materials have Nd as the dopant material and do not contain any of the rare earths Yb, Er, Tm or Ho as the dopant material.

In one other preferred embodiment, the overlapped emission luminescent materials have Yb as the dopant material and do not contain any of the rare earths Nd, Er, Tm or Ho as the dopant material.

In one other preferred embodiment, the overlapped emission luminescent materials have Er as the dopant material and do not contain any of the rare earths Nd, Yb, Tm or Ho as the dopant material.

By using these elements, based on the emission wavelength range, particularly good detectability can be obtained with a sensor of simple design.

The expression "as a dopant" means the usual use of such elements in the manufacture of luminescent materials, and typically from 0.1% to 50% of the filled positions of the matrix can be occupied by the dopant. This does not imply minor contamination of the respective elements, which may be introduced during the manufacture of the luminescent material, for example, depending on the selected purity of the original product.

In one embodiment, the luminescent materials for the overlapped emission value document system according to the invention respectively have different rare earth ions as emission centers or have mixtures of rare earth ions from the group {Nd, Yb, Er, Tm, Ho}. This makes it possible to use more complex effects, such as energy transfer systems or targeted modification of the spectral characteristic.

In a preferred embodiment, the overlapped emission luminescent materials have Nd and/or Yb and/or Er as dopant material, and do not contain any of the rare earths Tm or Ho as dopant.

In a preferred embodiment, the overlapped emission luminescent materials have Nd and/or Yb as dopant, and do not contain any of the rare earths Er, Tm or Ho as dopant.

By using these elements, particularly good detectability can be obtained by means of a sensor of simple design.

Preferably, the emission of the luminescent materials occurs substantially in the primary emission range. This means that apart from the partially overlapping bands of the emission spectrum, there are no other bands of the emission spectrum in other spectral ranges.

In this way, in an advantageous manner, when deriving conclusions about the emission spectrum bands of the primary emission range, it is prevented from separately evaluating other non-overlapping, isolated ones arising within the simulation of the emission spectrum bands. In a preferred embodiment of the invention, the luminescent materials are designed for this purpose in such a way that at least 80%, in particular at least 90%, of the individual intensities are emitted in the primary emission range.

In a particularly preferred embodiment, the various codings of the value document system can be produced by combining as few as possible as many luminescent materials as similar to each other as possible, as described hereinafter. In this way, particularly good protection against analysis and imitation of the security feature can be provided.

Preferably, the first and/or the second security feature luminescent material of the first value document has the same matrix as the first security feature luminescent material and/or, if appropriate, the second security feature luminescent material of the second value document.

Preferably, the value document system includes at least one third value document whose security feature has at least one luminescent material that has the same matrix as the first or second luminescent material of the security feature of the first value document, but differs in that however, by its alloying material and/or its dynamic damping characteristics.

Preferably at least three, particularly preferably at least 4, more preferably at least 5, different value document system codings consist of security features with the following properties: The security features consist exclusively of mixtures of substances with a first matrix and a second matrix, the first and /or the second matrix may have different alloying materials and/or different dynamic damping characteristics.

For example, the first matrix may be lutetium aluminum garnet (LuAG) and the second matrix yttrium vanadate (YVO ₄ ), which are doped, for example, with different volumes of neodymium to obtain fast (S) dynamic decay characteristics or slow (L) dynamic characteristics attenuation. In this case, for various codings of the value document system, for example, the following security features can be generated:

4 security features from different mixing ratios of LuAG:Nd (S) and YV0 ₄ :Nd (S)

4 security features from different mixing ratios of LuAG:Nd (S) and YV0 ₄ :Nd (L)

4 security features from different mixing ratios of LuAG:Nd (L) and YV0 ₄ :Nd (S)

4 security features from different mixing ratios of LuAG:Nd (L) and YV0 ₄ :Nd (L)

As a result, a system of valuable documents with 16 codings can be obtained, which are nevertheless mutually very similar and therefore only difficult to analyze and imitate by a forger.

In a preferred embodiment, the various encodings of the value document system differ from each other in at least one of their U, V or S values by at least 20%, preferably at least 50%, with respect to the smaller value. This ensures that the individual codings can be well distinguished.

In another preferred embodiment, the various codings of the value document system differ from each other in their V values by at least 20%, preferably by at least 50%.

In another preferred embodiment, the various codings of the value document system differ from each other in their U values by at least 20%, preferably by at least 50%.

In one other preferred embodiment, the various encodings of the value document system differ from each other in at least two of their U, V and S values by at least 20%, preferably by at least 50%.

This ensures that the separation of the encodings can not be carried out exclusively by means of the S values, since in this case less protection against forgery is provided than if, instead of this or in addition to it, the encodings are distinguished by means of the U or V values.

In another embodiment of the value document system according to the invention, the luminescent materials are configured such that the individual decay times of the luminescent materials are in the range of 50 µs to 5000 µs, preferably in the range of 100 µs to 1000 µs. Preferably, the individual decay period of the first luminescent material is in the range of 100 µs to 200 µs and the individual decay period of the second luminescent material is in the range of 400 µs to 1000 µs, whereby particularly good protection against security feature spoofing is possible.

First of all, luminescent materials with decay periods of more than 5 milliseconds according to the invention cannot be used in the processing of data on high-speed banknote sensors, since in this case banknotes are transported at speeds up to 12 meters per second. Detection or separation of such long decay periods cannot be performed because the banknote is moved out of the measuring field before the luminescence intensity decreases noticeably due to the decay period. In addition, the measurement of very short decay periods is technically expensive. Preferably, none of the luminescent materials has a decay period of more than 5000 µs, particularly preferably more than 2000 µs, especially preferably more than 1000 µs. This ensures a more accurate measurement of the damping period also at high transport speeds. Preferably, none of the luminescent materials has a decay period of less than 50 µs, particularly preferably less than 80 µs, especially preferably less than 100 µs. At shorter decay times, distinguishing background fluorescence from, for example, organic contaminants, becomes difficult.

According to the invention, inorganic luminescent materials can be used. Particularly preferred according to the invention are luminescent materials in which an inorganic base crystal lattice is suitably used as a matrix, which is doped with at least one doping material selected from rare earth metals (or their ions).

Adjusting the decay times of inorganic luminescent materials is known in the art. For example, adjustment can be made by means of the amount of alloying material (concentration quenching). Alternatively, additional dopant materials (fluorescence quenchers) can be used, usually using certain rare earths, such as samarium, praseodymium or dysprosium, or also certain transition metals, such as, for example, ferric ions, but also numerous others. elements. Alternatively, the decay period can be influenced by the size of the particles of the luminescent materials, especially in the range of nanoparticles, or by structural defects/defects or surface defects, and thus make it possible to control suitable conditions for the synthesis or processing of the luminescent materials. Preferably, within the scope of this invention, the decay periods are adjusted by concentration quenching or addition of fluorescence quenchers.

In one embodiment of the invention, the luminescent materials of the value document system, that is, at least the first and second luminescent materials of the security feature of the first value document and at least the first luminescent material of the second value document, are designed in such a way that they are, in particular, the first and the second luminescent materials of the first document of value are co-excited by the same wavelength, which makes it possible, above all, targeted and relatively strong excitation of the luminescent materials by means of a relatively thin spectral excitation pulse (light flash, eg laser). In this case, it is advantageous if the wavelength corresponds to the total absorption maximum in the excitation spectra of the luminescent materials or, in the case of different absorption maxima, makes it possible to excite at least 50% of the corresponding absorption maximum. In this case, the excitation can advantageously be carried out in the strong excitation band of the rare earth ions, which is present in both luminescent materials. As a result, an efficient overall excitation of the luminescent materials is possible. Preferably, this excitation band means both the absorption maximum of the respective excitation spectra and an absorption band which reaches at least 50% of the absorption maximum of the excitation spectrum.

The security feature of the second document of value can be represented by a single material, ie a single luminescent material, or a mixture of substances from different luminescent materials.

In one embodiment, individual materials and mixtures of security feature substances are homogeneously mixed powders. These powders are preferably located in the substrate of the value document, that is to say they are added, in the case of paper substrates, to the stock or placed, in the manufacture of polymer substrates, in the polymer or polymer layer of the polymer substrate. Alternatively, mixtures of security feature substances are added to the printing ink or varnish and then placed with them on the substrate.

In another embodiment, the individual components of the substance mixtures of the security feature of the first and/or the second document of value are present in a separated form, i.e. the first component of the mixture of substances or the first luminescent material is present in the first partial area of the first and/or, if appropriate, the second document of value, for example in paper pulp, and the second component of the mixture of substances or the second luminescent material is present in the second partial area of the first and/or, if necessary, the second document of value, for example in the printing layer on top of the paper pulp. In this case, the various partial areas must be at least partially spatially overlapped in reflected light and/or in transmitted light in such a way that both components can be measured simultaneously. Such a security feature with separately arranged luminescent materials exhibits an emission spectrum similar to that of a homogeneous mixture when measuring spatially overlapping regions.

The security feature of the value document system according to the invention can thus be placed in the substrate of the first and/or second value document, for example as a pigment, mottled fibers or dopant material. In addition, the security feature can be placed as ink or varnish on the first and/or second value documents. In addition, the security feature may be placed on the carrier material in the form of a security strip, identification thread, mottled fibers, confetti and/or patches. In addition, a combination of the presented possibilities is also assumed to be possible.

In addition, the invention extends to a method for identifying (that is, recognizing the presence or absence) of a security feature of a valuable document, carried out as described above. The method for identifying a value document of a value document system according to the invention includes the following steps:

excitation of the first and, if necessary, the second luminescent material of the security feature of the first and/or second documents of value;

detection of the change in time pattern of the total intensity of the emitted radiation of the first and, if necessary, the second luminescent material in at least two spectrally different detection channels, wherein at least one detection channel includes at least a partial portion of the primary emission range of the first and second luminescent materials;

detecting an effective decay period and/or intensity in at least two detection channels; And

identifying the coding and/or class of the security document of value based on the detected one or more decay periods and/or intensities and/or intensity ratios and/or decay period ratios of the primary emission range.

Preferably, the luminescent materials of the first and/or second value document are excited by a common excitation pulse.

In one embodiment of the method according to the invention, the primary emission range of the luminescent materials of the security feature of the first and/or second documents of value spans, respectively, several distinct detection channels. The detection channels may suitably include a partial portion of the primary emission band. However, it is also possible that part of the primary emission range and/or other emission ranges are located completely outside of all detection channels.

An embodiment of the method according to the invention may provide that at least two detection channels are located, wholly or partly, within the primary emission range of the luminescent materials of the first and/or second valuable documents. For example, the primary emission range is separable, for example, into two equally sized halves, each half being a detection channel. However, the detection channels do not have to be located exactly within the primary emission range, but may also be smaller or larger, and thus protrude, for example, outside the primary emission range or be offset from it. First of all, more than two detection channels may be located within the primary emission range, for example three detection channels.

In a preferred embodiment of the method according to the invention, at least two of the detection channels correspond to the spectral bands A, B of the security features of at least the first and optionally the second value documents of the value document system.

In a preferred embodiment of the method according to the invention, the individual detection channels each comprise one wavelength range of less than 400 nm, preferably less than 250 nm, particularly preferably less than 100 nm. According to one embodiment, all detection channels are substantially the same in size, that is, they differ from each other in their magnitudes by less than 10%. The term "value" in this connection corresponds to the spectral width (in nanometers) of the detection channel, measured at half the spectral sensitivity of the detection. According to another embodiment, the detection channels have at least partially different magnitudes (ie, one or more detection channels differ in their spectral width by more than 10%). For example, a detection channel has a magnitude of 100 nm and another detection channel has a magnitude of 150 nm. According to one embodiment, the individual detection channels are arranged continuously one behind the other.

For this, for example, the first detection channel measures the wavelength range between 900 nm and 1000 nm, the second detection channel the wavelength range between 1000 nm and 1100 nm, and the third detection channel the wavelength range between 1100 and 1200 nm. According to another embodiment, one or more detection channels have gaps between them that do not contain any other detection channel. For example, the first detection channel measures the wavelength range between 900 nm and 1000 nm, the second detection channel the wavelength range between 1000 nm and 1100 nm, and the third detection channel the wavelength range between 1150 nm and 1250 nm.

In one embodiment of the invention, the effective decay period t can be tested at different wavelengths or wavelength ranges (ie, two or more detection channels) to check the decay period performance. Here, the overall intensity can be adjusted by using a mono-exponential approximation over at least two reference points in the form I(t)=A⋅e ^-t/τ (attenuation factor). Thus, such a solution is an approximation in reality for a possibly more complex course of the process in time. This is a very fast and simple measurement method, which can be applied by selecting the luminescent materials according to the invention, or alternatively by the properties of the luminescent material.

In contrast to prior art combinations of luminescent materials, as known, for example, from US 9 046 486 B2, no complex detection methods are necessary to obtain increased security in an advantageous manner. In addition, the organic colorant molecules, compared to the luminescent materials according to the invention based on inorganic, matrix-based luminescent compositions, primarily have broader emission spectra and significantly shorter decay times, which are often in the nanosecond range. In addition, they have significantly smaller Stokes shifts. These properties are disadvantageous for selecting or checking the decay period. The method according to the invention thus enables a relatively simple, fast and reliable detection of a security feature.

The invention is explained below in more detail by way of example with the help of drawings. Shown on:

перекрытия;Fig. 1A - two separate emission spectra of individual materials and their area

overlaps;

Fig. 1B is the resulting emission spectrum of the mixture of individual materials from FIG. 1A, as well as its primary emission range PEB;

Fig. 2 is a schematic time evolution of two emission spectra of individual materials in different cases τ ₁ >τ ₂ , τ ₁ =τ ₂ or τ ₁ <τ ₂ ; And

Fig. 3A-D are schematic combinations of different luminescent materials based on their respective U ₁₂ and S ₁₂ values.

Fig. 2 schematically shows the time evolution of two emission spectra of individual materials in different cases τ ₁ >τ ₂ , τ ₁ =τ ₂ or τ ₁ <τ ₂ . In this case, the (individual) radiation intensities of two materials S1 and S2 in the primary emission range are correlated with the wavelength. The time course of the emission spectrum bands of both luminescent materials S1 and S2 with both periods τ ₁ or τ ₂ of attenuation is schematically illustrated, and in one case, the first luminescent material S1 has a longer decay period τ ₁ (solid line), and the second luminescent material S2 - shorter decay period τ ₂ (dashed line). In the second case, both the first and second luminescent materials S1, S2 have a long decay period (τ ₁ =τ ₂ ). In the third case, the first luminescent material S1 has a shorter decay period τ ₁ (solid line) and the second luminescent material S2 has a longer decay period τ ₂ (dotted line).

In order to test the security feature with luminescent materials S1 and S2 with individual decay periods τ ₁ or τ ₂ , different spectral ranges A, B can be processed (via the respective detection channels K_A, K_B). In this case, in three cases, the same emission spectrum is divided into two different detection channels K_A, K_B, and the time course of the spectral intensity is obtained, respectively, from diagrams placed one on top of the other (top to bottom).

Obviously, the spectral intensity of the emission spectrum band with a longer decay period remains unchanged during the observation period, while the spectral intensity of the emission spectrum band with a shorter decay period decreases significantly with time.

In one embodiment, the detection channels K_A and K_B jointly cover the primary emission band (respectively marked in the diagrams by the shaded area A and the framed area B). Therefore, the detection channels K_A and K_B respectively contain different components of the emission spectrum bands of the first and second luminescent materials. In the first case, K_A contains a large emissive component of the slowly decaying luminescent material S1 and a smaller emissive component of the rapidly decaying luminescent material S2. Thus measured in the detection channel K_A, the total decay period is relatively long. In contrast, the detection channel K_B contains a large emission component of the fast-decaying luminescent material S2 and a smaller emission component of the slowly-decaying luminescent material S1. Thus measured in the detection channel K_B, the total decay period is relatively short.

In the second case, both luminescent materials S1 and S2 decay slowly and have the same decay period. That is, both the detection channel K_A and the detection channel K_B measure the same long total decay period.

In the third case, channel K_A contains a large emissive component of the rapidly decaying luminescent material S1 and a smaller emissive component of the slowly decaying luminescent material S2. The total decay period thus measured is relatively short in the detection channel K_A and relatively long in the detection channel K_B.

In contrast to this simplified scheme, more than two spectral bands (detection channels) can also be used, for example three detection channels. Furthermore, these detection channels are usually not, as schematically represented here, sharply separated, but formed by the course of the spectral sensitivity of the detector or the filter characteristic of the filter applied to the detector.

The invention describes a system of valuable documents with special security features, consisting of a special combination of at least two luminescent materials, the emission spectra of which partially overlap. By selecting suitable materials and material properties according to the invention, such a value document system can be produced with the following advantageous properties: increased number of codings;

improved security against counterfeiting due to difficult analysis and simulation (exotic spectra…);

the ability to detect and separate using an inexpensive simple sensor with a small number of channels, for example, with two spectral channels;

Improved product feasibility through economies of scale and advantageous material properties.

In addition, the properties are chosen in such a way that verification is also possible at high banknote transport speeds.

In the following embodiments, various luminescent materials are qualitatively designated as "slow decay" or "quick decay". By this is meant that the "quickly decaying" materials have a significantly shorter decay period relative to the "slowly decaying" materials of one example. This does not imply any comparison between materials from different examples. In the examples, the decay times of the luminescent materials and their mixtures are quantified in terms of V and S values.

In subsequent embodiments, various luminescent materials are combined to mixtures of substances. At the same time, such a designation as "50% A, 50% C" means that both luminescent material A and luminescent material B are used in such a quantitative ratio that their individual intensity contributes, respectively, 50% of the total intensity. This does not necessarily mean that both luminescent materials are used in a mixture of substances in the same mass fraction. An alternative simple method for preparing such mixtures of substances, for example, consists in first diluting the individual luminescent materials with a non-luminescent filler such that all (diluted) luminescent materials have the same individual intensity.

In this case, the percentage values provided correspond to the respective mass constituents of the (diluted) luminescent materials in the mixtures of substances.

Fig. 3A-D show schematic embodiments, namely Example 1 (FIG. 3A), Example 2 (FIG. 3B), Example 3 (FIG. 3C) and Example 4 (FIG. 3D). Embodiments refer to luminescent materials A, B, C, or D.

They are indicated in the diagrams by their respective U ₁₂ and S ₁₂ values. In this case, double-sided arrows indicate which of the spectrally complementary luminescent materials can be mixed with each other within the corresponding embodiment to obtain additional encodings. However, the double-sided arrows do not necessarily indicate the course of the U ₁₂ and S ₁₂ values of such mixtures, but are purely symbolic. The exact values of U ₁₂ and S ₁₂ of the respective mixtures can be obtained from the respective tables of the embodiments. The indication of the values of U ₁₂ and S ₁₂ in this case is made as an example, for a better visualization of the embodiments. In addition to the U ₁₂ and S ₁₂ values, there are other values, primarily the V ₁₂ values, which can be used to separate different encodings, which, however, are not shown here. Encoding is also referred to as "code" within the embodiments.

The first embodiment according to the invention relates to a value document system with luminescent materials which are based on neodymium. For the production of a system of valuable documents, two lutetium-aluminum garnets with different volumes of neodymium doping, as well as neodymium-doped yttrium sulfoxide, were used:

Luminescent material A: LuAG:Nd, fast decay

Luminescent material B: LuAG:Nd, slow decay

Luminescent material C: Y ₂ O ₂ S: Nd, fast decaying

Luminescent materials show, when excited at 810 nm, respectively, one complex emission spectrum of several bands in the range of 1030-1130 nm.

The emission spectrum is divided into three spectral ranges, which correspond to the detection channels K1, K2, K3 of the sensor. The overall intensity found in the respective spectral ranges is appropriately designated as I_1, I_2, I_3, and the total decay periods as I_1, I_2, I_3. In this case, the spectral ranges extend in the following wavelength ranges:

Intensity ratios U, decay period ratios V, and the sum S of decay periods between different detection channels can be used to distinguish between different encodings of the value document system. They can be adjusted by combining one of the two luminescent materials A or B with luminescent material C. Additionally, pure single materials may differ from similar mixtures of substances.

In this case, for example, U ₁₂ denotes the ratio of intensities between K1 and K2:

Likewise is valid:

By provided in this embodiment, the decay periods mean effective decay periods. To detect them, luminescent materials or mixtures of substances are excited by an excitation pulse, one intensity is detected after the first waiting time, another intensity is detected after the second waiting time, and an effective decay period is detected from the difference in intensities after the first and second waiting times. For this, in the context of Example 1, the intensity values I ₁₀₀ after 100 µs and I ₃₀₀ after 300 µs are measured, and the effective decay period t is found as follows:

If the intensity values are taken, for example, at two other times as a base, or another algorithm is used to find effective decay periods, other total decay periods are obtained. Therefore, in order to bring measurement results or test criteria for such features according to the invention, an accurate knowledge of the measurement parameters is required, as a result of which the protective effect can be significantly increased.

Codes 1 to 9 can be distinguished from each other on the basis of their U, V and S values in such a way that it is possible to compile a value document system with them.

Example 1A: Value Document System with 9 Codes Separate materials or mixtures of substances of codes 1 to 9 respectively are used to secure a version of the value document. For example, code 1 is added to the paper stock of the first currency, code 2 is added to the paper stock of the second currency, code 3 is added to the paper stock of the third currency, and the like, whereby a total of 9 different currencies can be individually coded.

Example 1B: Value Document System with 2 Codes A mixture of code 2 substances is added to the pulp of the first currency. A mixture of code 3 substances is added to the paper stock of the second currency. Both currencies can differ from each other based on their U, V and S values.

Example 1B: Value Document System with 2 Codes A mixture of code 4 substances is added to the pulp of a first currency. A mixture of substances of code 9 is added to the paper pulp of the second currency. Both currencies can differ from each other based on their U, V and S values.

Example 1D: Value document system with 3 codings A mixture of code 7 substances is mixed with a first currency printing ink and printed. A mixture of substances of code 8 is mixed with the printing ink of the second currency and printed. The mixture of substances of code 9 is mixed with the printing ink of the third currency and printed. The three currencies can differ from each other based on their U, V, and S values.

In another, second embodiment, a valuable document system with ytterbium-based luminescent materials is described. In this case, two lutetium-aluminum garnets doped with different volumes of ytterbium, yttrium phosphate doped with ytterbium, and gadolinium sulfoxide doped with ytterbium were used:

Fluorescent material A: LuAGrYb / fast decay

Fluorescent material B: LuAGrYb / slow decay Fluorescent material C: Gd ₂ O ₂ S:Yb / fast decay

Fluorescent material D: YPO ₄ Yb / slow decay

Luminescent materials exhibit emission in the 950-1100 nm range when excited at 945 nm.

The emission spectrum is divided into two spectral ranges, which correspond to the detection channels K1, K2 of the sensor. The total intensity found in the respective spectral ranges is appropriately designated as I_1 and I_2, and the total decay periods as τ_1 and τ _{_} 2. In this case, the spectral ranges extend over the following wavelength ranges:

Intensity ratios U, decay period ratios V, and the sum S of the decay periods of both detection channels can be used to distinguish between different codings of the value document system. They can be customized by combining one of the two luminescent materials A or B with one of the two luminescent materials C or D. Additionally, pure single materials may differ from similar mixtures of substances.

In this case, for example, U12 denotes the ratio of intensities between K1 and K2:

Likewise is valid:

By the decay periods provided in the example, effective decay periods are meant. To detect them, luminescent materials or mixtures of substances are excited by means of an excitation pulse, the first intensity is detected after the first waiting time, the second intensity is detected after the second waiting time, and the effective decay period is detected from the difference in intensities after the first and second waiting times. For this, in the context of example 2, the intensity values I ₁₀₀ after 100 µs and I ₃₀₀ after 300 µs are measured, and the effective decay period t is found as follows:

If the intensity values are taken, for example, at two other times as a base, or another algorithm is used to find effective decay periods, other total decay periods are obtained. Therefore, in order to bring measurement results or test criteria for such features according to the invention, exact knowledge of the measurement parameters is required, as a result of which the protective effect can be significantly increased.

Codes 2-1 to 2-16 can be distinguished from each other on the basis of their U, V and S values in such a way that they can be used to compile a value document system.

Example 2A: Value Document System with 16 Codes Separate materials or mixtures of substances of codes 2-1 to 2-16 respectively are used to secure a version of the value document. For example, code 2-1 is added to the pulp of the first currency, code 2-2 is added to the paper pulp of the second currency, code 2-3 is added to the paper pulp of the third currency, and the like, whereby a total of 16 different currencies can be provided. individual coding.

Example 2B: Value document system with 2 codings A mixture of substances of codes 2-12 is added to the pulp of the first currency. A mixture of substances code 2-15 is added to the paper pulp of the second currency. Both currencies can be distinguished from each other based on their U, V and S values.

Another third embodiment relates to a value document system with luminescent materials that are based on erbium. In this case, the following three materials are used: erbium-doped yttrium aluminum garnet, erbium-doped yttrium vanadate without additional fluorescence quencher, and erbium-doped yttrium vanadate with a small amount of additional samarium alloying material to reduce the decay period:

Fluorescent material A: YAG:Er / slow decay

Fluorescent material B: YVO ₄ :Er / slow decay

Fluorescent material C: YVO ₄ :Er, Sm / fast decay

Luminescent materials exhibit emission in the 1400-1700 nm range when excited at 970 nm.

The emission spectrum is divided into three spectral ranges, which correspond to the detection channels K1, K2, K3 of the sensor. Detected in the respective spectral ranges, the total intensity is appropriately designated as I_1, I_2, I_3, and the total decay periods - as t_1, t_2, t_3. In this case, the spectral ranges extend in the following wavelength ranges:

Intensity ratios U, decay period ratios V, and the sum S of the decay periods of both detection channels can be used to distinguish between different codings of the value document system. They can be adjusted by combining luminescent material A with one of two luminescent materials B or C. Additionally, pure single materials can differ from mixtures of substances from single materials.

In this case, for example, U12 denotes the ratio of intensities between K1 and K2:

Likewise is valid:

By the decay periods provided in the example, effective decay periods are meant. To detect them, luminescent materials or mixtures of substances are excited by an excitation pulse, one intensity is detected after the first waiting time, another intensity is detected after the second waiting time, and an effective decay period is detected from the difference in intensities after the first and second waiting times.

For this, in the context of example 3, the intensity values I ₁₀₀ after 100 µs and I ₅₀₀ after 500 µs are measured, and the effective decay period t is found as follows:

If the intensity values are taken, for example, at two other times as a base, or another algorithm is used to find effective decay periods, other total decay periods are obtained. Therefore, in order to bring measurement results or test criteria for such features according to the invention, an accurate knowledge of the measurement parameters is required, as a result of which the protective effect can be significantly increased.

Codes 3-1 to 3-9 can be distinguished from each other on the basis of their U, V and S values in such a way that it is possible to compile a system of value documents with their help.

Example 3A Value Document System with 9 Codes Separate materials or mixtures of substances of codes 3-1 to 3-9 respectively are used to secure the value document variety. For example, code 3-1 is added to the paper pulp of the first currency, code 3-2 is added to the paper pulp of the second currency, code 3-3 is added to the paper pulp of the third currency, and the like, whereby a total of nine different currencies can be provided. individual coding.

Example 3B: Value document system with 2 codings A mixture of substances of codes 3-7 is added to the paper pulp of the first currency. A mixture of substances of code 3-9 is added to the paper pulp of the second currency. Both currencies can differ from each other based on their U, V and S values.

In another, fourth embodiment according to the invention, we are talking about a value document system with luminescent materials based on thulium and holmium. In this case, the following three materials are used: thulium-doped lutetium-aluminum garnet without an additional fluorescence quencher, thulium-doped lutetium-aluminum garnet with a small amount of additional praseodymium alloying material to reduce the decay period, and yttrium sulfoxide doped with neodymium, ytterbium and holmium.

Fluorescent material A: LuAG:Tm / slow decay

Luminescent material B: LuAG:Tm, Pr / fast decaying

Luminescent material C: Y ₂ O ₂ S: Nd, Yb, Ho / slowly decaying

Luminescent materials exhibit emission in the 1600-2100 nm range when excited at 810 nm.

The emission spectrum is divided into two spectral ranges, which correspond to the detection channels K1, K2 of the sensor. The total intensity found in the respective spectral ranges is appropriately designated as I_1 and I_2, and the total decay periods as t_1 and t_2. In this case, the spectral ranges extend in the following wavelength ranges:

Intensity ratios U, decay period ratios V, and the sum S of the decay periods of both detection channels can be used to distinguish between different codings of the value document system. They can be adjusted by combining one of the two luminescent materials A or B with luminescent material C. Additionally, pure single materials may differ from similar mixtures of substances.

In this case, for example, U12 denotes the ratio of intensities between K1 and K2:

Likewise is valid:

By the decay periods provided in the example, effective decay periods are meant. To detect them, luminescent materials or mixtures of substances are excited by means of an excitation pulse, the first intensity is detected after the first waiting time, the second intensity is detected after the second waiting time, and the effective decay period is detected from the difference in intensities after the first and second waiting times. For this, in the context of Example 4, the intensity values I ₁₀₀ after 100 µs and I ₅₀₀ after 500 µs are measured, and the effective decay period t is found as follows:

If the intensity values are taken, for example, at two other times as a base, or another algorithm is used to find effective decay periods, other total decay periods are obtained. Therefore, in order to bring measurement results or test criteria for such features according to the invention, an accurate knowledge of the measurement parameters is required, as a result of which the protective effect can be significantly increased.

Codes 4-1 to 4-9 can be distinguished from each other on the basis of their U, V and S values in such a way that it is possible to compile a value document system with them.

Example 4A Value Document System with 9 Codes Separate materials or mixtures of substances of codes 4-1 to 4-9 respectively are used to secure the value document variety. For example, code 4-1 is added to the pulp of the first currency, code 4-2 is added to the pulp of the second currency, code 4-3 is added to the pulp of the third currency, and the like, whereby a total of nine different currencies can be provided. individual coding.

Example 4B: Value document system with 2 codings A mixture of code 4-5 substances is added to the paper pulp of the first currency. A mixture of substances of code 4-8 is added to the paper pulp of the second currency. Both currencies can differ from each other based on their U, V and S values.

Claims (35)

1. A value document system that includes at least a first value document and a second value document, wherein the first valuable document has a security feature in the form of a combination of at least one first and one second luminescent material, and i. the first security feature luminescent material of the first value document is a first substance class luminescent material which includes doped garnet structures; ii. the second security feature luminescent material of the first value document is a second substance class luminescent material that includes doped rare earth sulfoxides, doped rare earth phosphates, and doped rare earth vanadates; iii. the first and second luminescent materials of the security feature of the first document of value have partially overlapping emission spectra; iv. the first and second luminescent materials of the security feature of the first document of value are jointly excited waves of the same length; v. the first and second luminescent materials of the security feature of the first document of value have a decay period of less than 5 ms; And vi. the first and second luminescent materials of the security feature of the first value document are designed in such a way that their primary emission range of overlapping emission spectra is separable into two different, directly adjacent spectral ranges, namely the first and second spectral ranges (A, B), which have a width at least 50 nm and maximum 500 nm; the second valuable document has a security feature with at least one first luminescent material from the first class of substances or from the second class of substances with a decay period of less than 5 ms, the emission of which is at least partially located in at least one of the adjacent spectral ranges A, IN; and the security feature of the first document of value has, compared to the security feature of the second document of value, at least a different ratio of emission intensities, a different ratio of decay periods and/or a different sum of decay periods in two adjacent spectral bands A, B. 2. The system of value documents according to claim 1, wherein the ratio of emission intensities is a quotient of the total intensity in the first spectral range and the total intensity in the second spectral range; the decay period ratio is a quotient of the total decay period in the first spectral range and the total decay period in the second spectral range; And the sum of the decay periods is the sum of the total decay period in the first spectral range and the total decay period in the second spectral range. 3. System of value documents according to claim 1 or 2, wherein different ratios of emission intensities, different ratios of attenuation periods and/or different sums of attenuation periods in the spectral ranges A, B, respectively, of the first and second documents of value are correlated with the coding of a security feature and/or recognition valuable documents of the first and/or second valuable documents. 4. The value document system according to one of the preceding claims, wherein the first and second security feature luminescent materials of the first value document and the first security feature luminescent material of the second value document have Nd, Yb or Er rare earth materials as emission centers. 5. The system of value documents according to one of the preceding claims, characterized in that the luminescent materials of the first class of substances are selected from doped yttrium aluminum garnets (YAG), lutetium aluminum garnets (LuAG), gadolinium gallium garnets (GGG), gadolinium scandium -gallium garnets (GSGG), yttrium-scandium-gallium garnets (YSGG), calcium-niobium-gallium garnets (CNGG), gadolinium-scandium-aluminum garnets (GSAG), calcium-lithium-niobium-gallium garnets (CLNGG) containing transition metals of garnet structures, especially yttrium iron garnets (YIG) or from mixed variants of such garnet structures. 6. The system of valuable documents according to one of the preceding paragraphs, characterized in that the luminescent materials of the second class of substances are selected from doped lanthanum sulfoxides, yttrium sulfoxides, gadolinium sulfoxides, lutetium sulfoxides, mixed sulfoxides based on them; and/or doped lanthanum phosphates, yttrium phosphates, gadolinium phosphates, lutetium phosphates, mixed phosphates based on them; and/or from lanthanum vanadates, yttrium vanadates, gadolinium vanadates, lutetium vanadates, and/or mixed vanadates based on them. 7. The value document system according to one of the preceding claims, wherein the degree of overlap of the partially overlapping emission spectra is greater than 5% and less than 80%. 8. The value document system according to one of the preceding claims, wherein the security feature of the second value document has a combination of a first luminescent material from a first substance class with a second luminescent material from a second substance class, or has a combination of a first luminescent material from a second substance class with a second luminescent material from a first class of substances, wherein the first and second luminescent materials of the second document of value i. have partially overlapping emission spectra; ii. are jointly excited waves of the same length; iii. respectively have a decay period of less than 5 ms. 9. The value document system according to one of the preceding claims, wherein the first and second security feature luminescent materials of the first value document and the first and, when present, the second luminescent material of the second value document are co-excited wavelengths. 10. The system of value documents according to one of the preceding claims, wherein the same matrix is used in the first or second luminescent material of the security feature of the first value document as in the first luminescent material or, if necessary, the second luminescent material of the security feature of the second value document. 11. The system of valuable documents according to one of paragraphs. 1-9, wherein the first and second security feature luminescent materials of the first value document use the same matrices as the first security feature luminescent material and the second security feature luminescent material of the second value document. 12. The system of value documents according to one of the preceding claims, wherein the first and second luminescent materials of the security feature of the first value document, as well as the first luminescent material of the second value document, use the same rare earth element as an emission center. 13. The system of value documents according to one of the preceding claims, characterized in that the corresponding decay period of the first and second luminescent material of the security feature of the first value document, as well as the first and, if necessary, the second luminescent material of the security feature of the second value document, is at least 0 .05 ms. 14. The system of value documents according to one of the preceding claims, characterized in that the first and second luminescent materials of the security feature of the first value document differ in their decay periods by less than 10%. 15. The system of valuable documents according to one of paragraphs. 1-13, characterized in that the first and second luminescent materials of the security feature of the first document of value differ in attenuation periods by 10 to 50% with respect to the shortest individual attenuation period of the luminescent materials. 16. The system of valuable documents according to one of paragraphs. 1-13, characterized in that the first and second luminescent materials of the security feature of the first document of value differ in decay periods by at least 50%, preferably more than 75%, particularly preferably more than 100%, with respect to the shortest individual decay period luminescent materials. 17. The system of value documents according to one of the preceding claims, characterized in that the coding or identification of the first and second document of value correspond respectively to the denomination and/or value. 18. A method for identifying valuable documents of a system of valuable documents according to one of paragraphs. 1-17 which includes steps: A. excitation of the first and, when present, the second security feature luminescent material; B. detecting a change in time pattern of the total intensity of the emitted radiation of the first and, when present, the second luminescent material in at least two spectrally different detection channels, the detection channels including, respectively, at least a partial portion of the primary emission range of the first and, when present, a second luminescent material; detecting a decay period and/or intensity in at least two detection channels; And B. identifying a class of security document of value based on the detected one or more decay periods and/or intensities and/or intensity ratios and/or decay period ratios of the primary emission band. 19. A set of luminescent materials for the manufacture of a system of valuable documents according to one of paragraphs. 1-17, which includes the first luminescent material of the first value document, the second luminescent material of the first value document, as well as the first luminescent material of the second value document and, if necessary, the second luminescent material of the second value document.

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