# US 10,766,294 B2 · Value document having security marking and method for identifying the security marking

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- Number: US 10,766,294 B2
- Document ID: US10766294B2
- Status: Granted
- Kind: B2
- Application number: 16/332,869
- Filed: 2017-09-14
- Published: 2019-11-28
- Granted: 2020-09-08
- Earliest claimed: 2016-09-14
- Assignees: Giesecke+Devrient Currency Technology GmbH
- Applicants: Giesecke+Devrient Currency Technology GmbH
- Inventors: Wolfgang Rauscher; Wolfgang Deckenbach
- Web page: https://patentgrep.com/patent/US10766294B2

## CPC

- B42D 25/378: Special inks
- B42D 25/373: Metallic materials
- G07D 7/1205: Testing spectral properties
- B42D 25/21: for multiple purposes
- B42D 25/23: Identity cards
- B42D 25/24: Passports
- B42D 25/29: Securities; Bank notes
- B42D 25/355: Security threads
- G07D 2207/00: Paper-money testing devices
- B42D: BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- G07D: HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING

## Abstract

A value document has a security marking in the form of at least two luminescing substances which are present in a defined relative quantitative share and are jointly excitable by one excitation pulse. The time courses of the intensities are different and at least one luminescing substance has a non-monoexponential time course. In a method for identifying the security marking, the time course of the total intensity is detected and a linear combination of a formula is adapted including time courses of the intensities of the luminescing substances. The security marking is identified on the basis of the linear coefficients.

## Claims

### Claim 1

A value document having a security marking in the form of at least two luminescing substances, wherein
the at least two luminescing substances are respectively present in a defined relative quantitative share, based on the total quantity of the at least two luminescing substances,
the at least two luminescing substances are jointly excitable by one excitation pulse,
time courses of intensities of emitted radiations of the at least two luminescing substances are different from each other, and
at least one luminescing substance of the at least two luminescing substances has a non-monoexponential time course of the intensity of the emitted radiation of the at least one luminescing substance.

### Claim 2 (depends on 1)

The value document according to claim 1, in which the at least two luminescing substances have overlapping, in particular identical, excitation spectra.

### Claim 3 (depends on 1)

The value document according to claim 1, in which the at least two luminescing substances have overlapping emission spectra.

### Claim 4 (depends on 1)

The value document according to claim 1, in which the security marking has luminescing substances whose time courses of the intensities of the emitted radiations have a Bray-Curtis distance of greater than 0.10.

### Claim 5 (depends on 1)

The value document according to claim 1, in which the at least two luminescing substances respectively have an intensity of the emitted radiation which is in the region of 5% to 95%, of the total intensity of the emitted radiations of the luminescing substances.

### Claim 6 (depends on 1)

The value document according to claim 1, in which the at least two luminescing substances respectively have a decay time in the region of 100 ns to 100 ms.

### Claim 7 (depends on 1)

The value document according to claim 1, in which at least one luminescing substance comprises a host lattice doped with at least one rare-earth metal and/or at least one transition metal.

### Claim 8 (depends on 1)

A method for identifying the security marking of a value document according to claim 1, which comprises the following steps:
i) jointly exciting the luminescing substances with one excitation pulse,
ii) detecting the time course of a total intensity of the emitted radiations of the luminescing substances,
iii) adapting a linear combination I(t) of the formula
I
⁡
(
t
)
=
∑
i
=
1
n
⁢
c
i
·
I
i
⁡
(
t
)
to the time course of the total intensity of the emitted radiations, wherein Ii(t) are time courses of the intensities of the radiations emitted by the luminescing substances and ci are linear coefficients, wherein the index i relates to the luminescing substances and n indicates the number of luminescing substances, wherein the linear coefficients ci are ascertained, and
iv) identifying the security marking on the basis of the linear coefficients ci.

### Claim 9 (depends on 8)

The method according to claim 8, in which in step iii) the linear coefficients ci are determined such that absolute deviations of the linear combination I(t) from data points of the time course of the detected total intensity are minimized.

### Claim 10 (depends on 9)

The method according to claim 9, in which the linear coefficients ci are determined by the method of least squares such that the sum of the square deviations of the linear combination I(t) from data points of the time course of the detected total intensity of the emitted radiations are minimized.

### Claim 11 (depends on 8)

The method according to claim 8, in which step iv) comprises the following substeps:
iv-1) for n−1 linear coefficients ci: respectively ascertaining a ratio value Mi for each linear coefficient ci, which results from the ratio of the linear coefficient ci to at least one further linear coefficient ci or to a sum of ci and at least one further linear coefficient ci,
iv-2) for each ratio value Mi: checking whether the ratio value Mi is within an associated, definable or defined values range Wi,
iv-3) for each ratio value Mi: assigning the attribute “ratio value accepted”, if the ratio value Mi is within the associated values range Wi, or the attribute “ratio value not accepted”, if the ratio value Mi is outside the associated values range Wi,
iv-4) identifying the security marking, if all ratio values Mi have been assigned the attribute “ratio value accepted”.

### Claim 12

The method according to 11, in which in step iv-1) the ratio Mi is ascertained by the ratio of the associated linear coefficient ci to the sum of all linear coefficients ci.

### Claim 13 (depends on 8)

The method according to claim 8, which has a further step v) which comprises the following substeps:
v-1) ascertaining a measure value G characterizing the goodness of the adaptation of the linear combination I(t) to the time course of the total intensity of the luminescing substances,
v-2) comparing the measure value G with a threshold value,
v-3) assigning the attribute “measure value accepted” to the measure value G, if the measure value G is greater than the threshold value, or the attribute “measure value not accepted”, if the measure value G is smaller than or equal to the threshold value, and
v-4) identifying the security marking, if the measure value G has been evaluated with the attribute “measure value accepted”.

### Claim 14 (depends on 13)

The method according to claim 13, in which the measure value G is the coefficient of determination R2, wherein the threshold value is 0.9.

### Claim 15 (depends on 8)

The method according to claim 8, in which in step ii) more data points for detecting the total intensity are captured in a first time period immediately following the switching-off of the excitation pulse than in a second time period immediately following the first time period, wherein the first time period and the second time period are of equal length.