Patent ID: 12194772

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

FIG.2shows, schematically, the temporal evolution of two single-substance emission spectra for the different cases τ1>τ2, τ1=τ2ανδτ1<τ2. Here, the emitted (individual) intensity of two substances S1and S2in the primary emission range is plotted against the wavelength. The temporal progression of the emission bands of the two luminescent substances S1and S2having the two decay times τ1and τ2, respectively, is illustrated schematically, in one case, a first luminescent substance S1having a longer decay time τ1(solid line), and a second luminescent substance S2, a shorter decay time τ2(dotted line). In a second case, both the first and the second luminescent substance S1, S2have a long decay time (τ1=τ2). In a third case, a first luminescent substance S1has a shorter decay time τ1(solid line) and a second luminescent substance S2a longer decay time τ2(dotted line).

To check a security feature having luminescent substances S1and S2having individual decay times τ1and τ2, 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).

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.

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 S1and 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 S2and 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.

In the second case, both luminescent substances S1and S2are 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.

In the third case, channel K_A includes more emission fractions of the fast-decaying luminescent substance S1and 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.

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.

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:increased number of codingsimproved counterfeit security due to more complicated analysis and imitation (exotic spectra, . . . )detection and resolvability possible with an economical, simple sensor having few, e.g. 2, spectral channelsimproved manufacturability due to scale effects and favorable substance properties.

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

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.

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.

FIGS.3A-Dshow 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.

Said substances are listed in the diagrams based on their respective U12and S12values. 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 U12and S12values of such mixtures, but rather are purely symbolic. The precise U12and S12values of the respective mixtures can be found in the corresponding tables in the exemplary embodiments. Here, the U12and S12values are plotted by way of example for better visualization of the exemplary embodiments. In addition to the U12and S12values, there exist further values, especially the V12values, 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”.

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 decayingLuminescent substance B: LuAG:Nd, slow decayingLuminescent substance C: Y2O2S:Nd, fast decaying

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

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→I_1, τ_1K2: 1175-1100 nm→I_2, τ_2K3: 1100-1125 nm→I_3, τ_3

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.

Here, U12, for example, refers to the intensity ratio between K1 and K2:
U12=I_1/I_2

Analogously:
U23=I_2/I_3
U13=I_1/I_3
V12=τ_1/τ_2
V13=τ_1/τ_3
V23=τ_2/τ_3
S12=τ_1+τ_2
S13=τ_1+τ_3
S23=τ_2+τ_3

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 I300after 300 μs and the effective decay time τ determined as follows:
τ=−200 μs/ln(I300/I100)

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.

LuminescentS12S13S23Codesubstances usedU12U13U23V12V13V23[μs][μs][μs]1100% A4.332.890.67111178178178267% A, 33% C1.452.781.92111178178178350% A, 50% C0.952.702.85111178178178433% A, 67% C0.632.594.111111781781785100% C0.262.218.411111781781786100% B4.273.070.72111562562562767% B, 33% C1.452.922.021.621.020.62423518416850% B, 50% C0.952.822.971.841.040.56380483370933% B, 67% C0.632.684.241.931.060.55337431323

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

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

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

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

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.

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 decayingLuminescent substance B: LuAG:Yb/slow decayingLuminescent substance C: Gd2O2S:Yb/fast decayingLuminescent substance D: YPO4:Yb/slow decaying

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

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→I_1, τ_1K2: 1000-1100 nm→I_2, τ_2

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.

Here, U12, for example, refers to the intensity ratio between K1 and K2:
U12=I_1/I_2

Analogously:
V12=τ_1/τ_2
S12=τ_1+τ_2

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 I100are measured after 100 μs and I300after 300 μs and the effective decay time τ determined as follows:
τ=−200 μs/ln(I300/I100)

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.

S12CodeLuminescent substances usedU12V12[μs]2-1100% A0.3814002-2100% B0.37118202-3100% C5.5513602-4100% D2.35114402-525% B, 75% D1.460.9215352-650% B, 50% D0.940.9016142-775% B, 25% D0.600.9216962-825% A, 75% C2.380.953742-950% A, 50% C1.280.943812-1075% A, 25% C0.720.953882-1125% A, 75% D1.471.5010352-1250% A, 50% D0.961.698052-1375% A, 25% D0.621.556072-1425% B, 75% C2.360.437102-1550% B, 50% C1.260.409622-1675% B, 25% C0.700.501222

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

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

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.

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 decayingLuminescent substance B: YVO4:Er/slow decayingLuminescent substance C: YVO4:Er, Sm/fast decaying

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

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→I_1, τ_1K2: 1500-1600 nm→I_2, τ_2K2: 1600-1700 nm→I_3, τ_3

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.

Here, U12, for example, refers to the intensity ratio between K1 and K2:
U12=I_1/I_2

Analogously:
U23=I_2/I_3
U13=I_1/I_3
V12=τ_1/τ_2
V13=τ_1/τ_3
V23=τ_2/τ_3
S12=τ_1+τ_2
S13=τ_1+τ_3
S23=τ_2+τ_3

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 I500after 500 μs and the effective decay time τ determined as follows:
τ=−400 μs/ln(I500/I100)

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.

LuminescentS12S13S23Codesubstances usedU12U13U23V12V13V23[μs][μs][μs]3-1100% A0.400.400.991112400240024003-2100% B0.111.2611.911112200220022003-3100% C0.111.2611.911118008008003-425% A, 75% B0.150.694.651.020.980.962250230222783-550% A, 50% B0.200.522.561.030.980.962295234923163-675% A, 25% B0.280.441.561.020.990.972342237823523-725% A, 75% C0.150.694.651.290.740.571071141912823-850% A, 50% C0.200.522.561.410.800.561374181415813-975% A, 25% C0.280.441.561.320.890.67175921271882

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

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

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.

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.Luminescent substance A: LuAG:Tm/slow decayingLuminescent substance B: LuAG:Tm, Pr/fast decayingLuminescent substance C: Y2O2S:Nd, Yb, Ho/slow decaying

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

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→I_1, τ_1K2: 2000-2100 nm→I_2, τ_2

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.

Here, U12, for example, refers to the intensity ratio between K1 and K2:
U12=I_1/I_2

Analogously:
V12=τ_1/τ_2
S12=τ_1+τ_2

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 I500after 500 μs and the effective decay time τ determined as follows:
τ=−400 μs/ln(I500/I100)

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.

S12CodeLuminescent substances usedU12V12[μs]4-1100% A9.34124004-2100% B9.09112004-3100% C0.80118004-425% A, 75% C1.271.1019204-550% A, 50% C2.071.1620244-675% A, 25% C3.731.1621394-725% B, 75% C1.270.8716404-850% B, 50% C2.060.8115294-975% B, 25% C3.690.811413

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

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

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.