Authenticity feature in the form of luminescent substances

Patent metadata

Field	Value
Publication number	US-9987874-B2
Application number	US-201514662345-A
Country	US
Kind code	B2
Filing date	Mar 19, 2015
Priority date	Dec 16, 2009
Publication date	Jun 5, 2018
Grant date	Jun 5, 2018

Abstract

A security element has at least two luminescent substances, in which the security element has a first and a second luminescent substance which have a substantially identical, joint emission band. The first or the second luminescent substance, or both luminescent substances, have at least one excitation band that leads to an emission at the joint emission band only in the case of the first or the second luminescent substance.

First claim

The invention claimed is:

1. A checking method for verifying a security element, the method comprising the steps:
providing the security element that includes
a first luminescent substance having a first emission spectrum; and
a second luminescent substance having a second emission spectrum, wherein
the first emission spectrum and the second emission spectrum each include at least one substantially identical joint emission band,
the first luminescent substance has at least a first excitation band and a second excitation band that each produces an emission at the joint emission band,
the second luminescent substance has at least a first excitation band that produces an emission at the joint emission band, and
the first excitation band of the first luminescent substance is different than the first excitation band of the second luminescent substance;

illuminating the luminescent substances with a first radiation which has a wavelength lying substantially at the first excitation band of the first luminescent substance;
detecting the emission at the substantially identical joint emission band;
illuminating the luminescent substances with a second radiation which has a wavelength lying substantially at the first excitation band of the second luminescent substance; and
detecting the emission at the substantially identical joint emission band.

2. A security element comprising:
a first luminescence system, which includes a combination of first and second luminophores, and
a second luminescence system, which includes a combination of third and fourth luminophores, wherein
the first luminophor of the first luminescence system has a first emission spectrum and the third luminophor of the second luminescence system has second emission spectrum, wherein the first emission spectrum and the second emission spectrum overlap at least at one substantially identical joint emission band, and
the first luminophor has a first excitation spectrum and the third luminophor has a second excitation spectrum, wherein
the first excitation spectrum has at least a first excitation band and a second excitation band that each produce an emission of the first luminophor at the joint emission band,
the second excitation spectrum has at least a first excitation band and a second excitation band that each produce an emission of the third luminophor at the joint emission band;
the first excitation band of the first excitation spectrum is different than the first excitation band of the second excitation spectrum; and
the second excitation band of the first excitation spectrum is substantially identical to the second excitation band of the second excitation spectrum.

3. The security element of claim 2 , wherein the first and second excitation bands of the excitation spectrum of the first luminophor do not overlap.

4. The security element of claim 2 , wherein first and second luminescent systems have a complete or partial spatial overlap.

5. The security element of claim 2 , wherein each of the first and the second luminescent systems can be excited individually.

6. The security element of claim 2 , wherein illumination of the security element with radiation
at the first excitation band of the excitation spectrum of the first luminophor;
at the first excitation band of the excitation spectrum of the third luminophor; and
at the second excitation band of the first and third luminophores;

results in a luminescence intensity of the first luminophor at the joint emission band at a predetermined intensity relation to a luminescence intensity of the third luminophor at the joint emission band.

7. The security element of claim 2 , wherein illumination of the security element with radiation
at the first excitation band of the excitation spectrum of the first luminophor;
at the first excitation band of the excitation spectrum of the third luminophor; and
at the second excitation band of the first and third luminophores;

results in a luminescence rise and/or decay time of the first luminophor at the joint emission band at a predetermined temporal relation to a luminescence rise and/or decay time of the third luminophor at the joint emission band.

8. The security element of claim 2 , wherein illumination of the security element with radiation
at the first excitation band of the excitation spectrum of the first luminophor;
at the first excitation band of the excitation spectrum of the third luminophor; and
at the second excitation band of the first and third luminophores;

results in a luminescence spectral shape of the first luminophor at the joint emission band at a predetermined relation to a luminescence spectral shape of the third luminophor at the joint emission band.

9. A value document comprising the security element according to claim 2 , wherein the value document comprises at least one of paper and plastic.

10. The value document of claim 9 , wherein the first luminescence system and the second luminescence system are independently applied to the value document.

11. An authentication method for verifying a presence of the security element according to claim 2 , comprising at least two of the following steps:
jointly exciting the first luminophor and the third luminophor with a first radiation, which has a wavelength which is substantially included in the second excitation band of the first and the second excitation spectrum, and detecting a first emission at the joint emission band;
individually exciting the first luminophor with a second radiation, which has a wavelength which is substantially included in the first excitation band of the first excitation spectrum and detecting a second emission at the joint emission band;
individually exciting the third luminophor with a third radiation, which has a wavelength which is substantially included in the first excitation band of the second excitation spectrum and detecting a third emission at the joint emission band; and
relating the properties of the detected first, second, and third emission at the joint emission band.

12. The authentication method of claim 11 , further comprising:
jointly exciting the first luminophor and the second luminophor with a combined radiation of at least two of the first radiation, the second radiation, and the third radiation,
and detecting a fourth emission at the joint emission band.

13. The authentication method of claim 11 , further comprising:
selectively exciting the third luminophor and/or the fourth luminophor, and detecting the properties of the resulting emission.

14. The authentication method of claim 11 , wherein the luminescence intensities of the detected emissions are related for authentication.

15. An authentication method of claim 11 , wherein the exciting radiation is time-modulated and luminescence rise times or luminescence decay times of the detected emissions are related for authentication.

16. The authentication method of claim 11 , wherein spectral shapes of the detected emissions are related for authentication.

17. A sensor system for the authentication of value documents according to claim 9 , comprising two independent sensors, wherein each sensor is configured to detect a separate luminescence system.

18. The sensor system of claim 17 , wherein the first sensor is configured to illuminate the value documents with excitation radiation in at least a first and a second wavelength band;
the second sensor is configured to illuminate the value documents with excitation radiation in at least a first and a third wavelength band;

Assignees

• Giesecke & Devrient Gmbh
• Giesecke & Devrient Currency Technology Gmbh

Inventors

• Giering Thomas
• Kersten Peter
• Magg Ulrich
• Grauvogl Gregor

Classifications

• G01N21/6447

  by visual observation · CPC title

• B42D25/21

  for multiple purposes · CPC title

• B42D25/382

  absorbing or reflecting infrared light · CPC title

• G01N21/01

  Arrangements or apparatus for facilitating the optical investigation · CPC title

• G01N2201/06113

  Coherent sources; lasers · CPC title