VALUABLE DOCUMENT SYSTEM

Abstract

A value document system, a method for identifying a value document of a value document system, and a luminescent substance set, wherein the value document system includes at least a first value document and a second value document. The first value document has a security feature composed of a combination of at least a first and a second luminescent substance of a first or a second substance class. The second value document has a security feature with at least a first luminescent substance of the first or second substance class. The security feature of the first value document has at least a different intensity ratio of the emission, a different decay time ratio and/or a different decay time sum in two adjacent spectral ranges compared with the security feature of the second value document.

Claims

1.-19. (canceled)

20. A value document system, comprising at least a first value document and a second value document, the first value document comprising a security feature composed of a combination of at least a first and a second luminescent substance, i. the first luminescent substance of the security feature of the first value document being a luminescent substance of a first substance class, comprising doped garnet structures; ii. the second luminescent substance of the security feature of the first value document being a luminescent substance of a second substance class, comprising doped rare earth oxysulfides, doped rare earth-phosphates and doped rare earth vanadates; iii. the first and the second luminescent substance of the security feature of the first value document having partially overlapping emission spectra; iv. the first and the second luminescent substance of the security feature of the first value document being jointly excitable at one wavelength; v. the first and the second luminescent substance of the security feature of the first value document having a decay time of less than 5 ms; and vi. the first and second luminescent substance of the security feature of the first value document being formed in such a way that the primary emission range of their partially overlapping emission spectra is dividable in-to two different, directly adjacent spectral ranges, namely a first and a second spectral range, which have a width of at least 50 nm and a maximum of 500 nm; the second value document comprising a security feature having at least a first luminescent substance from the first substance class or from the second substance class having a decay time of less than 5 ms, whose emission is at least partially in at least one of the adjacent spectral ranges A, B; and the security feature of the first value document having at least a different in-tensity ratio of the emission, a different decay time ratio and/or a different decay time sum in the two adjacent spectral ranges A, B compared with the security feature of the second value document.

21. The value document system according to claim 20, the intensity ratio of the emission being the quotient of the total intensity in the first spectral range and the total intensity in the second spectral range; the decay time ratio being the quotient of the total decay time in the first spectral range and the total decay time in the second spectral range; and the decay time sum being the sum of the total decay time in the first spectral range and the total decay time in the second spectral range.

22. The value document system according to claim 20, the different intensity ratios of the emission, the different decay time ratios and/or the different decay time sums in the spectral ranges A, B of, in each case, the first and second value document being assigned to a coding of the security feature and/or a value document identifier of the first and/or second value document.

23. The value document system according to claim 20, the first and second luminescent substances in the security feature of the first value document and the first luminescent substance of the security feature of the second value document having, as emission centers, the rare earths Nd, Yb or Er as the dopant.

24. The value document system according to claim 20, wherein the luminescent substances of the first substance class are selected from doped yttrium aluminum garnets (YAG), lutetium aluminum garnets (Lu-AG), 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), transition-metal-containing garnet structures, yttrium iron garnets (YIG) or mixed variants of these garnet structures.

25. The value document system according to claim 20, wherein the luminescent substances of the second substance class are selected from doped lanthanum oxysulfides, yttrium oxysulfides, gadolinium oxysulfides, lutetium oxysulfides, mixed oxysulfides based on these; and/or doped lanthanum phosphates, yttrium phosphates, gadolinium phosphates, lutetium phosphates, mixed phosphates based on these; and/or lanthanum vanadates, yttrium vanadates, gadolinium vanadates, lutetium vanadates, and/or mixed vanadates based on these.

26. The value document system according to claim 20, the degree of overlap of the partially overlapping emission spectra being greater than 5% and less than 80%.

27. The value document system according to claim 20, the security feature of the second value document comprising a combination of the first luminescent substance from the first substance class with a second luminescent substance from the second substance class or comprising a combination of the first luminescent substance from the second substance class with a second luminescent substance from the first substance class, the first and second luminescent sub-stances of the second value document i. having partially overlapping emission spectra; ii. being jointly excitable at one wavelength; iii. each having a decay time of less than 5 ms.

28. The value document system according to claim 20, the first and second luminescent substances in the security feature of the first value document, as well as the first and, if present, second luminescent substance of the second value document being jointly excitable at one wavelength.

29. The value document system according to claim 20, the first or second luminescent substance of the security feature of the first value document using the same matrix as the first luminescent substance or the, if applicable, second luminescent substance of the security feature of the second value document.

30. The value document system according to claim 20, the first and second luminescent substance of the security feature of the first value document using the same matrices as the first luminescent substance and second luminescent substance of the security feature of the second value document.

31. The value document system according to claim 20, the first and second luminescent substance of the security feature of the first value document and the first luminescent substance of the second value document using the same rare earth as the emission center.

32. The value document system according to claim 20, wherein the respective decay time of the first and second luminescent sub-stance of the security feature of the first value document and of the first and, if applicable, second luminescent substance of the security feature of the second value document is at least 0.05 ms.

33. The value document system according to claim 20, wherein the first and second luminescent substance of the security feature of the first value document differ in their decay time by less than 10%.

34. The value document system according to claim 20, wherein the first and second luminescent substance of the security feature of the first value document differ in decay time by 10% to 50% with respect to the shortest individual decay time of the luminescent substances.

35. The value document system according to claim 20, wherein the first and second luminescent substance of the security feature of the first value document differ in decay time by at least 50% with respect to the shortest individual decay time of the luminescent substances.

36. The value document system according to claim 20, wherein the coding or identifier of the first and second value document correspond to one denomination and/or one value each.

37. A method for identifying a value document of a value document system according to claim 20, comprising the steps: a. exciting the first and, if present, second luminescent substance of the security feature; b. detecting the temporal progression of a total intensity of the emitted radiations of the first and, if present, second luminescent substance in at least two spectrally different detection channels, the detection channels each encom-passing at least a sub-range of the primary emission range of the first and, if present, second luminescent substance; determining a decay time and/or in-tensity in the at least two detection channels; and c. identifying a value document class from the security feature based on the determined one or more decay times and/or intensities and/or intensity ratios and/or decay time ratios of the primary emission range.

38. A luminescent substance set for manufacturing a value document system according to claim 20, comprising the first luminescent substance of the first value document, the second luminescent substance of the first value document and the first luminescent substance of the second value document and, if applicable, the second luminescent substance of the second value document.

Description

[0135] The invention is further explained in the following by way of example based on the drawings. Shown are:

[0136] FIG. 1A two single-substance emission spectra and their overlap range ÜB;

[0137] FIG. 1B the resulting emission spectrum of the mixture of the single substances in FIG. 1A and its primary emission range PEB;

[0138] FIG. 2 schematically, the temporal evolution of two single-substance emission spectra for the different cases τ.sub.1>τ.sub.2, τ.sub.1=τ.sub.2 and τ.sub.1<τ.sub.2; and

[0139] FIG. 3 A-D schematically, combinations of different luminescent substances based on their respective U.sub.12 and S.sub.12 values.

[0140] FIG. 2 shows, schematically, the temporal evolution of two single-substance emission spectra for the different cases τ.sub.1>τ.sub.2, τ.sub.1=τ.sub.2 ανδτ.sub.1<τ.sub.2. Here, the emitted (individual) intensity of two substances S1 and S2 in the primary emission range is plotted against the wavelength. The temporal progression of the emission bands of the two luminescent substances S1 and S2 having the two decay times τ.sub.1 and τ.sub.2, respectively, is illustrated schematically, in one case, a first luminescent substance S1 having a longer decay time τ.sub.1 (solid line), and a second luminescent substance S2, a shorter decay time τ.sub.2 (dotted line). In a second case, both the first and the second luminescent substance S1, S2 have a long decay time (τ.sub.1=τ.sub.2). In a third case, a first luminescent substance S1 has a shorter decay time τ.sub.1 (solid line) and a second luminescent substance S2 a longer decay time τ.sub.2 (dotted line).

[0141] To check a security feature having luminescent substances S1 and S2 having individual decay times τ.sub.1 and τ.sub.2, respectively, different spectral ranges A, B can be analyzed (via corresponding detection channels K_A, K_B). Here, the same emission spectrum is separated for the three cases into two different detection channels K_A, K_B each, the temporal progression of the spectral intensity resulting from the diagrams arranged, in each case, above or below one another (from top to bottom).

[0142] In the observation period, the spectral intensity of the emission band having the longer decay time evidently remains unchanged, whereas the spectral intensity of the emission band having the shorter decay time decreases sharply with time.

[0143] In one embodiment, the detection channels K_A and K_B together cover the primary emission range (each marked in the diagrams by a hatched range A and an outlined range B). Accordingly, different fractions of the emission bands of the first and second luminescent substance are included in each of the detection channels K_A and K_B. In the first case, K_A encompasses more emission fractions of the slow-decaying luminescent substance S1 and fewer emission fractions of the fast-decaying luminescent substance S2. The total decay time measured in the detection channel K_A is thus relatively long. In contrast to this, the detection channel K_B includes more emission fractions of the fast-decaying luminescent substance S2 and fewer emission fractions of the slow-decaying luminescent substance S1. The total decay time measured in the detection channel K_B is thus relatively short.

[0144] In the second case, both luminescent substances S1 and S2 are slow decaying and have the same decay time. The same long total decay time is therefore measured in both detection channel K_A and detection channel K_B.

[0145] In the third case, channel K_A includes more emission fractions of the fast-decaying luminescent substance S1 and fewer emission fractions of the slow-decaying luminescent substance S2. Thus, the total decay time measured in the detection channel K_A is relatively short and the total decay time measured in the detection channel K_B is relatively long.

[0146] Contrary to this simplified diagram, it is also possible to work with more than two spectral ranges (detection channels), for example three detection channels. Furthermore, said detection channels are normally not, as schematically depicted here, clearly separated, but are shaped by the spectral progression of the sensitivity curve of the detector or the filter curve of a filter used in the detector.

[0147] The present invention describes a value document system having special security features, consisting of a special combination of at least two luminescent substances whose emission spectra partially overlap. In this way, through an inventive selection of suitable substances and substance properties, a value document system having advantageous properties can be produced: [0148] increased number of codings [0149] improved counterfeit security due to more complicated analysis and imitation (exotic spectra, . . . ) [0150] detection and resolvability possible with an economical, simple sensor having few, e.g. 2, spectral channels [0151] improved manufacturability due to scale effects and favorable substance properties.

[0152] Furthermore, the properties are chosen in such a way that a check is also possible at high transport speeds of the banknote.

[0153] In the following exemplary embodiments, the different luminescent substances are referred to qualitatively as “slow decaying” or “fast decaying”. This means that the “fast-decaying” substances have a significantly shorter decay time relative to the “slow-decaying” substances of the same example. Thus, it does not mean a comparison between substances from different examples. Quantitative statements on decay times of the luminescent substances and their mixtures are given by the V and S values in the examples.

[0154] In the following exemplary embodiments, different luminescent substances are combined to form substance mixtures. Here, a designation such as “50% A, 50% C” means that both luminescent substance A and luminescent substance B were used in such a ratio that their individual intensity each contributes 50% to the total intensity. It does not necessarily mean that the two luminescent substances were used in the substance mixture in the same mass fraction. An alternative simple method for manufacturing such substance mixtures is, for example, to first dilute the individual luminescent substances with a non-luminescent filler in such a way that all (diluted) luminescent substances have the same individual intensity. In this case, the percentages indicated then correspond to the respective mass fractions of the (diluted) luminescent substances in the substance mixtures.

[0155] FIGS. 3A-D show schematic exemplary embodiments, namely example 1 (FIG. 3A), example 2 (FIG. 3B), example 3 (FIG. 3C) and example 4 (FIG. 3D). The exemplary embodiments relate to luminescent substances A, B, C and D.

[0156] Said substances are listed in the diagrams based on their respective U.sub.12 and S.sub.12 values. Here, the double arrows denote which of the spectrally complementary luminescent substances are mixed with one another to produce additional codings within the scope of the respective exemplary embodiment. However, the double arrows do not necessarily denote the progression of the U.sub.12 and S.sub.12 values of such mixtures, but rather are purely symbolic. The precise U.sub.12 and S.sub.12 values of the respective mixtures can be found in the corresponding tables in the exemplary embodiments. Here, the U.sub.12 and S.sub.12 values are plotted by way of example for better visualization of the exemplary embodiments. In addition to the U.sub.12 and S.sub.12 values, there exist further values, especially the V.sub.12 values, which are used to separate the different codings, but were not plotted here. Within the scope of the exemplary embodiments, a coding is also referred to as a “code”.

[0157] A first exemplary embodiment according to the present invention relates to a value document system having luminescent substances that are based on neodymium. To generate the value document system, two lutetium aluminum garnets doped with different amounts of neodymium and an yttrium oxysulfide doped with neodymium are used:

Luminescent substance A: LuAG:Nd, fast decaying
Luminescent substance B: LuAG:Nd, slow decaying
Luminescent substance C: Y.sub.2O.sub.2S:Nd, fast decaying

[0158] When excited at 810 nm, the luminescent substances each exhibit a complex emission spectrum composed of multiple bands in the 1030-1130 nm range.

[0159] The emission spectrum is divided into three spectral ranges, which correspond to the detection channels K1, K2, K3 of the sensor. The total intensities detected in the respective spectral ranges are accordingly referred to as I_1, I_2, I_3, and the total decay times as τ_1, τ_2, τ_3. Here, the spectral ranges span the following wavelength ranges:

K1: 1050-1075 nm.fwdarw.I_1, τ_1
K2: 1175-1100 nm.fwdarw.I_2, τ_2
K3: 1100-1125 nm.fwdarw.I_3, τ_3

[0160] To differentiate the different codings of the value document system, the intensity ratios U, decay time ratios V and the decay time sum S between the different detection channels are used. These can be adjusted by combining one of the two luminescent substances A or B with the luminescent substance C. In addition, the pure single substances can be differentiated from such substance mixtures.

[0161] Here, U.sub.12, for example, refers to the intensity ratio between K1 and K2:

U.sub.12=I_1/I_2

[0162] Analogously:

U.sub.23=I_2/I_3

U.sub.13=I_1/I_3

V.sub.12=τ_1/τ_2

V.sub.13=τ_1/τ_3

V.sub.23=τ_2/τ_3

S.sub.12=τ_1+τ_2

S.sub.13=τ_1+τ_3

S.sub.23=τ_2+τ_3

[0163] The decay times specified in this exemplary embodiment are effective decay times. To determine them, the luminescent substances or substance mixtures are excited by an excitation pulse, an intensity is determined after a first waiting time has lapsed, a further intensity is determined after a second waiting time has lapsed, and the effective decay time is determined from the intensity difference in the first and the second waiting time. For this, within the scope of example 1, the intensity values Iwo are measured after 100 μs and I.sub.300 after 300 μs and the effective decay time τ determined as follows:

τ=−200 μs/ln(I.sub.300/I.sub.100)

[0164] If the intensity values at two other times, for example, are taken as the basis, or another algorithm is applied to determine the effective decay times, then other total decay times result. Thus, to reproduce the measurement data or test criteria of such inventive features, it is necessary to know the measurement parameters precisely, which significantly increases the protective effect.

TABLE-US-00001 Luminescent S.sub.12 S.sub.13 S.sub.23 Code substances used U.sub.12 U.sub.13 U.sub.23 V.sub.12 V.sub.13 V.sub.23 [μs] [μs] [μs] 1 100% A 4.33 2.89 0.67 1 1 1 178 178 178 2 67% A, 33% C 1.45 2.78 1.92 1 1 1 178 178 178 3 50% A, 50% C 0.95 2.70 2.85 1 1 1 178 178 178 4 33% A, 67% C 0.63 2.59 4.11 1 1 1 178 178 178 5 100% C 0.26 2.21 8.41 1 1 1 178 178 178 6 100% B 4.27 3.07 0.72 1 1 1 562 562 562 7 67% B, 33% C 1.45 2.92 2.02 1.62 1.02 0.62 423 518 416 8 50% B, 50% C 0.95 2.82 2.97 1.84 1.04 0.56 380 483 370 9 33% B, 67% C 0.63 2.68 4.24 1.93 1.06 0.55 337 431 323

[0165] The codes 1 to 9 can be differentiated from one another based on their U, V and S values, such that it is possible to set up a value document system with them.

EXAMPLE 1a: VALUE DOCUMENT SYSTEM HAVING 9 CODINGS

[0166] The single substances or substance mixtures of codes 1 to 9 are used to secure one type of value document each. For example, code 1 is added to the paper pulp of a first currency, code 2 is added to the paper pulp of a second currency, code 3 is added to the paper pulp of a third currency, etc., permitting a total of 9 different currencies to be furnished with an individual coding.

EXAMPLE 1b: VALUE DOCUMENT SYSTEM HAVING 2 CODINGS

[0167] The substance mixture of code 2 is introduced into the paper pulp of a first currency. The substance mixture of code 3 is introduced into the paper pulp of a second currency. The two currencies can be differentiated from one another based on their U, V and S values.

EXAMPLE 1c: VALUE DOCUMENT SYSTEM HAVING 2 CODINGS

[0168] The substance mixture of code 4 is introduced into the paper pulp of a first currency. The substance mixture of code 9 is introduced into the paper pulp of a second currency. The two currencies can be differentiated from one another based on their U, V and S values.

EXAMPLE 1d: VALUE DOCUMENT SYSTEM HAVING 3 CODINGS

[0169] The substance mixture of code 7 is mixed into the printing ink of a first currency and imprinted. The substance mixture of code 8 is mixed into the printing ink of a second currency and imprinted. The substance mixture of code 9 is mixed into the printing ink of a third currency and imprinted. The three currencies can be differentiated from one another based on their U, V and S values.

[0170] In a further, second exemplary embodiment, a value document system having luminescent substances based on ytterbium is described. Here, two lutetium aluminum garnets doped with different amounts of ytterbium, an yttrium phosphate doped with ytterbium and a gadolinium oxysulfide doped with ytterbium are used:

Luminescent substance A: LuAG:Yb/fast decaying
Luminescent substance B: LuAG:Yb/slow decaying
Luminescent substance C: Gd.sub.2O.sub.2S:Yb/fast decaying
Luminescent substance D: YPO.sub.4:Yb/slow decaying

[0171] When excited at 945 nm, the luminescent substances exhibit an emission in the 950-1100 nm range.

[0172] The emission spectrum is divided into two spectral ranges, which correspond to the detection channels K1, K2 of the sensor. The total intensities detected in the respective spectral ranges are accordingly referred to as I_1 and I_2, and the total decay times as τ_1 and τ_2. Here, the spectral ranges span the following wavelength ranges:

K1: 950-1000 nm.fwdarw.I_1, τ_1
K2: 1000-1100 nm.fwdarw.I_2, τ_2

[0173] To differentiate the different codings of the value document system, the intensity ratio U, decay time ratio V and the decay time sum S of the two detection channels are used. These can be adjusted by combining one of the two luminescent substances A or B with one of the two luminescent substances C or D. In addition, the pure single substances can be differentiated from such substance mixtures.

[0174] Here, U.sub.12, for example, refers to the intensity ratio between K1 and K2:

U.sub.12=I_1/I_2

[0175] Analogously:

V.sub.12=τ_1/τ_2

S.sub.12=τ_1+τ_2

[0176] The decay times indicated in the example are effective decay times. To determine them, the luminescent substances or substance mixtures are excited by an excitation pulse, an intensity is determined after a first waiting time has lapsed, an intensity is determined after a second waiting time has lapsed, and the effective decay time is determined from the intensity difference in the first and the second waiting time. For this, within the scope of example 2, the intensity values I.sub.100 are measured after 100 μs and I.sub.300 after 300 μs and the effective decay time τ determined as follows:

τ=−200 μs/ln(I.sub.300/I.sub.100)

[0177] If the intensity values at two other times, for example, are taken as the basis, or another algorithm is applied to determine the effective decay times, then other total decay times result. Thus, to reproduce the measurement data or test criteria of such inventive features, it is necessary to know the measurement parameters precisely, which significantly increases the protective effect.

TABLE-US-00002 S.sub.12 Code Luminescent substances used U.sub.12 V.sub.12 [μs] 2-1 100% A 0.38 1 400 2-2 100% B 0.37 1 1820 2-3 100% C 5.55 1 360 2-4 100% D 2.35 1 1440 2-5 25% B, 75% D 1.46 0.92 1535 2-6 50% B, 50% D 0.94 0.90 1614 2-7 75% B, 25% D 0.60 0.92 1696 2-8 25% A, 75% C 2.38 0.95 374 2-9 50% A, 50% C 1.28 0.94 381 2-10 75% A, 25% C 0.72 0.95 388 2-11 25% A, 75% D 1.47 1.50 1035 2-12 50% A, 50% D 0.96 1.69 805 2-13 75% A, 25% D 0.62 1.55 607 2-14 25% B, 75% C 2.36 0.43 710 2-15 50% B, 50% C 1.26 0.40 962 2-16 75% B, 25% C 0.70 0.50 1222

[0178] The codes 2-1 to 2-16 can be differentiated from one another based on their U, V and S values, such that it is possible to set up a value document system with them.

EXAMPLE 2a: VALUE DOCUMENT SYSTEM HAVING 16 CODINGS

[0179] The single substances or substance mixtures of codes 2-1 to 2-16 are used to secure one type of value document each. For example, code 2-1 is added to the paper pulp of a first currency, code 2-2 is added to the paper pulp of a second currency, code 2-3 is added to the paper pulp of a third currency, etc., permitting a total of 16 different currencies to be furnished with an individual coding.

EXAMPLE 2b: VALUE DOCUMENT SYSTEM HAVING 2 CODINGS

[0180] The substance mixture of code 2-12 is introduced into the paper pulp of a first currency. The substance mixture of code 2-15 is introduced into the paper pulp of a second currency. The two currencies can be differentiated from one another based on their U, V and S values.

[0181] A further, third exemplary embodiment relates to a value document system having luminescent substances that are based on erbium. Here, the following three substances are used: an yttrium aluminum garnet doped with erbium, an yttrium vanadate doped with erbium without an additional quencher, and an yttrium vanadate doped with erbium with a low samarium codoping to reduce the decay time:

Luminescent substance A: YAG:Er/slow decaying
Luminescent substance B: YVO.sub.4:Er/slow decaying
Luminescent substance C: YVO.sub.4:Er, Sm/fast decaying

[0182] When excited at a wavelength of 970 nm, the luminescent substances exhibit an emission in the 1400-1700 nm range.

[0183] The emission spectrum is divided into three spectral ranges, which correspond to the detection channels K1, K2, K3 of the sensor. The total intensities detected in the respective spectral ranges are accordingly referred to as I_1, I_2, I_3, and the total decay times as τ_1, τ_2, τ_3. Here, the spectral ranges span the following wavelength ranges:

K1: 1400-1500 nm.fwdarw.I_1, τ_1
K2: 1500-1600 nm.fwdarw.I_2, τ_2
K2: 1600-1700 nm.fwdarw.I_3, τ_3

[0184] To differentiate the different codings of the value document system, the intensity ratio U, decay time ratio V and the decay time sum S of the two detection channels are used. These can be adjusted by combining the luminescent substance A with one of the luminescent substances B or C. In addition, the pure single substances can be differentiated from substance mixtures composed of the single substances.

[0185] Here, U.sub.12, for example, refers to the intensity ratio between K1 and K2:

U.sub.12=I_1/I_2

[0186] Analogously:

U.sub.23=I_2/I_3

U.sub.13=I_1/I_3

V.sub.12=τ_1/τ_2

V.sub.13=τ_1/τ_3

V.sub.23=τ_2/τ_3

S.sub.12=τ_1+τ_2

S.sub.13=τ_1+τ_3

S.sub.23=τ_2+τ_3

[0187] The decay times indicated in the example are effective decay times. To determine them, the luminescent substances or substance mixtures are excited by an excitation pulse, an intensity is determined after a first waiting time has lapsed, an intensity is determined after a second waiting time has lapsed, and the effective decay time is determined from the intensity difference in the first and the second waiting time. For this, within the scope of example 3, the intensity values Iwo are measured after 100 μs and I.sub.500 after 500 μs and the effective decay time τ determined as follows:

τ=−400 μs/ln(I.sub.500/I.sub.100)

[0188] If the intensity values at two other times, for example, are taken as the basis, or another algorithm is applied to determine the effective decay times, then other total decay times result. Thus, to reproduce the measurement data or test criteria of such inventive features, it is necessary to know the measurement parameters precisely, which significantly increases the protective effect.

TABLE-US-00003 Luminescent S.sub.12 S.sub.13 S.sub.23 Code substances used U.sub.12 U.sub.13 U.sub.23 V.sub.12 V.sub.13 V.sub.23 [μs] [μs] [μs] 3-1 100% A 0.40 0.40 0.99 1 1 1 2400 2400 2400 3-2 100% B 0.11 1.26 11.91 1 1 1 2200 2200 2200 3-3 100% C 0.11 1.26 11.91 1 1 1 800 800 800 3-4 25% A, 75% B 0.15 0.69 4.65 1.02 0.98 0.96 2250 2302 2278 3-5 50% A, 50% B 0.20 0.52 2.56 1.03 0.98 0.96 2295 2349 2316 3-6 75% A, 25% B 0.28 0.44 1.56 1.02 0.99 0.97 2342 2378 2352 3-7 25% A, 75% C 0.15 0.69 4.65 1.29 0.74 0.57 1071 1419 1282 3-8 50% A, 50% C 0.20 0.52 2.56 1.41 0.80 0.56 1374 1814 1581 3-9 75% A, 25% C 0.28 0.44 1.56 1.32 0.89 0.67 1759 2127 1882

[0189] The codes 3-1 to 3-9 can be differentiated from one another based on their U, V and S values, such that it is possible to set up a value document system with them.

EXAMPLE 3a: VALUE DOCUMENT SYSTEM HAVING 9 CODINGS

[0190] The single substances or substance mixtures of codes 3-1 to 3-9 are used to secure one type of value document each. For example, code 3-1 is added to the paper pulp of a first currency, code 3-2 is added to the paper pulp of a second currency, code 3-3 is added to the paper pulp of a third currency, etc., permitting a total of nine different currencies to be furnished with an individual coding.

EXAMPLE 3b: VALUE DOCUMENT SYSTEM HAVING 2 CODINGS

[0191] The substance mixture of code 3-7 is introduced into the paper pulp of a first currency. The substance mixture of code 3-9 is introduced into the paper pulp of a second currency. The two currencies can be differentiated from one another based on their U, V and S values.

[0192] In a further, fourth exemplary embodiment according to the present invention, it is a value document system having luminescent substances, based on thulium and holmium. Here, the following three substances are used: a lutetium aluminum garnet doped with thulium without additional quencher, a lutetium aluminum garnet doped with thulium with a low praseodymium codoping to reduce the decay time, and an yttrium oxysulfide doped with neodymium, ytterbium and holmium.

[0193] Luminescent substance A: LuAG:Tm/slow decaying

[0194] Luminescent substance B: LuAG:Tm, Pr/fast decaying

[0195] Luminescent substance C: Y.sub.2O.sub.2S:Nd, Yb, Ho/slow decaying

[0196] When excited at 810 nm, the luminescent substances exhibit an emission in the 1600-2100 nm range.

[0197] The emission spectrum is divided into two spectral ranges, which correspond to the detection channels K1, K2 of the sensor. The total intensities detected in the respective spectral ranges are accordingly referred to as I_1 and I_2, and the total decay times as τ_1 and τ_2. Here, the spectral ranges span the following wavelength ranges:

K1: 1500-2000 nm.fwdarw.I_1, τ_1
K2: 2000-2100 nm.fwdarw.I_2, τ_2

[0198] To differentiate the different codings of the value document system, the intensity ratio U, the decay time ratio V and the decay time sum S of the two detection channels are used. These can be adjusted by combining one of the two luminescent substances A or B with luminescent substance C. In addition, the pure single substances can be differentiated from such substance mixtures.

[0199] Here, U.sub.12, for example, refers to the intensity ratio between K1 and K2:

U.sub.12=I_1/I_2

[0200] Analogously:

V.sub.12=τ_1/τ_2

S.sub.12=τ_1+τ_2

[0201] The decay times indicated in the example are effective decay times. To determine them, the luminescent substances or substance mixtures are excited by an excitation pulse, an intensity is determined after a first waiting time has lapsed, an intensity is determined after a second waiting time has lapsed, and the effective decay time is determined from the intensity difference in the first and the second waiting time. For this, within the scope of example 4, the intensity values Iwo are measured after 100 μs and I.sub.500 after 500 μs and the effective decay time τ determined as follows:

τ=−400 μs/ln(I.sub.500/I.sub.100)

[0202] If the intensity values at two other times, for example, are taken as the basis, or another algorithm is applied to determine the effective decay times, then other total decay times result. Thus, to reproduce the measurement data or test criteria of such inventive features, it is necessary to know the measurement parameters precisely, which significantly increases the protective effect.

TABLE-US-00004 S.sub.12 Code Luminescent substances used U.sub.12 V.sub.12 [μs] 4-1 100% A 9.34 1 2400 4-2 100% B 9.09 1 1200 4-3 100% C 0.80 1 1800 4-4 25% A, 75% C 1.27 1.10 1920 4-5 50% A, 50% C 2.07 1.16 2024 4-6 75% A, 25% C 3.73 1.16 2139 4-7 25% B, 75% C 1.27 0.87 1640 4-8 50% B, 50% C 2.06 0.81 1529 4-9 75% B, 25% C 3.69 0.81 1413

[0203] The codes 4-1 to 4-9 can be differentiated from one another based on their U, V and S values, such that it is possible to set up a value document system with them.

EXAMPLE 4a: VALUE DOCUMENT SYSTEM HAVING 9 CODINGS

[0204] The single substances or substance mixtures of codes 4-1 to 4-9 are used to secure one type of value document each. For example, code 4-1 is added to the paper pulp of a first currency, code 4-2 is added to the paper pulp of a second currency, code 4-3 is added to the paper pulp of a third currency, etc., permitting a total of nine different currencies to be furnished with an individual coding.

EXAMPLE 4b: VALUE DOCUMENT SYSTEM HAVING 2 CODINGS

[0205] The substance mixture of code 4-5 is introduced into the paper pulp of a first currency. The substance mixture of code 4-8 is introduced into the paper pulp of a second currency. The two currencies can be differentiated from one another based on their U, V and S values.