Coding System For Value Documents

• US 20070202352A1
• Filed: 10/05/2004
• Published: 08/30/2007
• Est. Priority Date: 10/08/2003
• Status: Active Grant

• Current Assignee: Giesecke & Devrient (Giesecke & Devrient GmbH)
• Original Assignee: Giesecke & Devrient GmbH
• Inventors: Rauscher, Wolfgang, Giering, Thomas
• Granted Patent: US 7,927,511 B2
• Time in Patent Office: Days
• US Class Current: 428/690
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: B42D 25/387 absorbing or reflecting ultraviolet light
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]

Abstract

The invention relates to a coding having at least one pair of mutually associated luminescent substances having first and second luminescent substances which emit in a joint emission range located outside the visible spectral range. The emission spectra of the first and second luminescent substances overlap in at least a subrange of the stated emission range such that the emission spectrum of the first luminescent substance is complemented by the emission spectrum of the second luminescent substance.

Claims

1. A coding comprising at least one pair of mutually associated luminescent substances having first and second luminescent substances which emit in a joint emission range located outside the visible spectral range, the emission spectra of the first and second luminescent substances overlapping in at least a subrange of said joint emission range such that the emission spectrum of the first luminescent substance is complemented characteristically by the emission spectrum of the second luminescent substance.

2. The coding according to claim 1, wherein said joint emission range extends in a range selected from the group consisting of from about 750 nm to about 2500 nm;

from about 800 nm to about 2200 nm; and

, from about 1000 nm to about 1700 nm.

3. The coding according to claim 1, wherein at least one of the first and second luminescent substance is formed on the basis of a doped host lattice.

4. The coding according to claim 1, wherein at least one of the first and second luminescent substance is formed on the basis of a host lattice doped with rare earth elements.

5. The coding according to claim 4, wherein the host lattice is doped with one or more of dopants selected from the group consisting of neodymium, erbium, holmium, thulium, ytterbium, praseodymium, and dysprosium.

6. The coding according to claim 1, wherein at least one of the first and second luminescent substance is formed on the basis of a host lattice doped with a chromophore, the chromophore being selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc.

7. The coding according to claim 6, wherein at least one of the host lattices is doped with a plurality of chromophores.

8. The coding according to claim 3, wherein at least one of the host lattices is formed by a mixed crystal.

9. The coding according to claim 3, wherein the first and second luminescent substances are formed on the basis of different host lattices which have crystal fields of different strength and which are each doped with the same dopant.

10. The coding according to claim 1, wherein the subrange where the emission spectra of the first and second luminescent substances complementarily overlap has a width of 200 nm or less.

11. The coding according to claim 1, wherein the subrange where the emission spectra of the first and second luminescent substances complementarily overlap extends in a range selected from the group consisting of from about 850 nm to about 970 nm;

from about 920 nm to about 1060 nm;

from about 1040 nm to about 1140 nm;

from about 1100 nm to about 1400 nm;

from about 1100 nm to about 1250 nm;

from about 1120 nm to about 1220 nm;

from about 1300 nm to about 1500 nm; and

from about 1400 nm to about 1700 nm.

12. The coding according to claim 1, wherein the first and second luminescent substances have in said subrange at least one emission line in each case whose positions have a distance apart of about 30 nm or less.

13. The coding according to claim 1, wherein the coding contains a further luminescent substance which has at least one emission line outside said subrange.

14. The coding according to claim 13, wherein the at least one emission line is outside the visible spectral range.

15. The coding according to claim 1, wherein the coding system includes a plurality of pairs of said mutually associated luminescent substances.

16. The coding according to claim 15, wherein the subranges where the emission spectra of the first and second luminescent substances of a pair overlap each other complementarily are different for different pairs of mutually associated luminescent substances.

17. The coding according to claim 1, wherein the coding has at least a second luminescent substance which likewise emits in said subrange, and the emission spectrum of at least one of the first and second luminescent substance is complemented characteristically.

18. A coding system for value documents comprising at least one pair of mutually associated luminescent substances having first and second luminescent substances which emit in a joint emission range located outside the visible spectral range, the emission spectrum of the first and second luminescent substances overlapping in at least a subrange of the said joint emission range such that the emission spectrum of the first luminescent substance is complemented characteristically by the emission spectrum of the second luminescent substance and value documents to be distinguished comprise either or both different first and second luminescent substances.