Printed document having a value and comprising a luminescent authenticity feature based on a host lattice

• US 6,344,261 B1
• Filed: 12/06/1999
• Issued: 02/05/2002
• Est. Priority Date: 02/02/1998
• Status: Expired due to Term

• Current Assignee: Giesecke & Devrient (Giesecke & Devrient GmbH)
• Original Assignee: Giesecke & Devrient GmbH
• Inventors: Kaule, Wittich, Schwenk, Gerhard, Stenzel, Gerhard
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): BLACKWELL, GWENDOLYN
• Application Number:
  US09/381,641
• Time in Patent Office: 792 Days
• Field of Search: 428/67, 428/199, 428/203, 428/204, 428/201, 428/211, 428/333, 428/403, 428/464, 428/537.5, 428/690, 428/913, 428/916, 283/74, 283/57, 283/904, 283/901, 283/113, 283/114, 283/107, 427/7, 427/57, 252/301.4 R
• US Class Current: 428/195.1
• CPC Class Codes: B41M 3/144 using fluorescent, luminescent or iridescent effects
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: C09K 11/7708 Vanadates; Chromates; Molybdates; Tungstates
• CPC Class Codes: C09K 11/7776 Vanadates; Chromates; Molybdates; Tungstates
• CPC Class Codes: G06K 19/06046 Constructional details
• CPC Class Codes: Y10S 283/901 Concealed data
• CPC Class Codes: Y10S 283/904 Credit card
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10S 428/916 Fraud or tamper detecting
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/31993 Of paper

Abstract

The invention concerns a printed valuable document with at least one authentication feature in the form of a luminescent substance based on a host lattice doped with at least one rare earth metal. The host lattice largely absorbs in the entire visible region of the spectrum, is excitable in large parts of the visible region of the spectrum and at least partially transparent in at least the wavelength range between 0.8 μm and 1.1 μm. In addition, the host lattice contains chromium as an absorptive substance in such a concentration that amplification of the emission by the luminescent substance takes place. The rare earth metal emits in the wavelength region between 0.8 μm and 1.1 μm.

Claims

1. Printed valuable document with at least one authentication feature comprising a luminescent substance based on a host lattice doped with at least one rare earth metal, which largely absorbs throughout the visible region of the spectrum, is excitable in substantial parts of the visible region of the spectrum, and is at least partially transparent at least in the wavelength range between 0.8 μ

m and 1.1 μ

m, whereby the rare earth metal emits in the wavelength range between 0.8 μ

m and 1.1 μ

m, and the host lattice contains chromium as an absorptive substance in such a concentration that amplification of the emission by the luminescent substance takes place.

2. Printed valuable document according to claim 1, wherein the rare earth metal is ytterbium, praseodymium or neodymium.

3. Printed valuable document according to claim 1, wherein the host lattice has only one rare earth metal doping.

4. Printed valuable document according to claim 1, wherein the chromium concentration lies in the range from 2 to 30 percent by weight.

5. Printed valuable document according to claim 1, wherein the rare earth metal is present in a concentration between 0.5 and 20 percent by weight.

6. Printed valuable document according to claim 1, wherein the host lattice has a garnet or perovskite structure.

7. Printed valuable document according to claim 6, wherein the garnet structure satisfies with the general formula

8. Printed valuable document according to claim 7, wherein the index x fulfils the condition 0.3<

x<

2.5.

9. Printed valuable document according to claim 7, wherein the luminescent substance satisfies the formula

10. Printed valuable document according to claim 7, wherein the luminescent substance satisfies the formula

11. Printed valuable document according to claim 7, wherein the luminescent substance satisfies the formula

12. Printed valuable document according to claim 6, wherein the perovskite structure satisfies the general formula

13. Printed valuable document according to claim 12, wherein the luminescent substance satisfies the general formula

14. Printed valuable document according to claim 12, wherein the luminescent substance satisfies the general formula

15. Printed valuable document according to claim 12, wherein the luminescent substance satisfies the general formula

16. Printed valuable document according to claim 1, wherein the luminescent substance is mixed with a printing ink that also contains visible colour additions.

17. Printed valuable document according to claim 1, wherein the luminescent substance is incorporated into the volume of the valuable document.

18. Printed valuable document according to claim 1, wherein the luminescent substance is provided as an invisible and at least partial coating on the valuable document.

19. Printed valuable document according to claim 18, wherein the coating is in the form of a stripe.

28. Printed valuable document according to claim 4, wherein the chromium concentration lies in the range from 5 to 15 percent by weight.

29. Printed valuable document according to claim 5, wherein the rare earth metal is present in a concentration between 0.8 and 13 percent by weight.

30. Printed valuable document according to claim 8, wherein the index x fulfils the condition 0.5<

x<

2.

31. Printed valuable document according to claim 9, wherein the luminescent substance satisfies the formula

 

Y<sub>3−

z</sub>Nd_zCr<sub>5−

x</sub>Al_xO₁₂

where the index z fulfils the condition 0.02<

z<

0.1.

32. Printed valuable document according to claim 10, wherein the luminescent substance satisfies the formula

33. Printed valuable document according to claim 11, wherein the luminescent substance satisfies the formula

34. Printed valuable document according to claim 13, wherein the luminescent substance satisfies the general formula

35. Printed valuable document according to claim 14, wherein the luminescent substance satisfies the general formula

36. Printed valuable document according to claim 15, wherein the luminescent substance satisfies the general formula

37. Printed valuable document according to claim 17, wherein the luminescent substance is incorporated into the valuable document which consists of paper.

20. Security element having at least one substrate material and a luminescent substance based on a host lattice doped with at least one rare earth metal, which largely absorbs in the visible region of the spectrum, is excitable in substantial parts of the visible spectrum and is at least partially transparent at least in the wavelength region between 0.8 μ

m and 1.1 μ

m, whereby the rare earth metal emits in the wavelength range between 0.8 μ

m and 1.1 μ

m, and the host lattice contains chromium as the absorptive substance in such a concentration that amplification of the emission of the luminescent substance results.

21. Security element according to claim 20, wherein the luminescent substance is incorporated into the substrate material.

22. Security element according to claim 21, wherein the luminescent substance is present in the substrate material in a concentration between 0.01 and 10 percent by weight.

23. Security element according to claim 20, wherein the luminescent substance is present in a layer applied to the substrate material.

24. Security element according to claim 23, wherein the luminescent substance is present in a printing ink in a concentration between 0.5 and 40 percent by weight.

25. Security element according to claim 20, wherein the substrate material consists of plastic.

26. Security element according to claim 20, wherein the substrate material consists of paper.

27. Security element according to claim 20, wherein the substrate material is formed as a security thread, mottling thread, planchet or label.

38. Security element according to claim 22, wherein the luminescent substance is present in the substrate material in a concentration between 0.1 and 5 percent by weight.

39. Security element according to claim 24, wherein the luminescent substance is present in a printing ink in a concentration between 20 and 30 percent by weight.