Thin-Layer Element Having an Interference Layer Structure

• US 20120170124A1
• Filed: 09/10/2010
• Published: 07/05/2012
• Est. Priority Date: 09/15/2009
• Status: Active Grant

• Current Assignee: Giesecke & Devrient (Giesecke & Devrient GmbH)
• Original Assignee: Giesecke & Devrient GmbH
• Inventors: Heim, Manfred, Liebler, Ralf, Fuhse, Christian, Rahm, Michael
• Granted Patent: US 9,274,258 B2
• Time in Patent Office: Days
• US Class Current: 359/585
• CPC Class Codes: B42D 2035/24 Colours
• CPC Class Codes: B42D 2035/36 visible in transmitted light, e.g. in a window region
• CPC Class Codes: B42D 25/23 Identity cards
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: B42D 25/324 Reliefs
• CPC Class Codes: B42D 25/328 Diffraction gratings; Holograms
• CPC Class Codes: B42D 25/351 Translucent or partly translucent parts, e.g. windows
• CPC Class Codes: B42D 25/36 comprising special materials
• CPC Class Codes: B42D 25/373 Metallic materials
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361

Abstract

The present invention relates to a thin-film element (30) having an interference layer structure for security papers, value documents and the like, having at least two semitransparent absorber layers (34, 38) and at least one dielectric spacing layer (36) arranged between the at least two absorber layers. According to the present invention, it is provided that the two absorber layers (34, 38) are each formed from a material having a complex refractive index N whose real part n and imaginary part k differ at least in a portion of the visible spectral range by a factor of 5 or more.

Claims

1. A thin-film element comprising an interference layer structure for security papers, value documents and the like, comprising at least two semitransparent absorber layers and at least one dielectric spacing layer arranged between the at least two absorber layers, in which

the two absorber layers are each formed from a material having a complex refractive index N whose real part n and imaginary part k differ at least in a portion of the visible spectral range by a factor of 5 or more,

the thin-film element appears shiny metallic and substantially color neutral when viewed in reflected light and colored in transmitted light, the thin-film element exhibiting a chroma C*_ab, specified in the CIELAB color space, of more than 15 in transmitted light.

2. The thin-film element according to claim 1, characterized in that the two absorber layers are formed from different materials, the real part n1 and imaginary part k1 of the material of one of the two absorber layers differing at least in a portion of the visible spectral range by a factor of 5 or more, and the real part n2 and imaginary part k2 of the material of the other of the two absorber layers differing by a factor of 8 or more, preferably by a factor of 10 or more, particularly preferably by a factor of 15 or more.

3. The thin-film element according to claim 1, characterized in that the real part n and imaginary part k of the materials of both absorber layers differ at least in a portion of the visible spectral range by a factor of 8 or more, preferably by a factor of 10 or more, particularly preferably by a factor of 15 or more.

4. The thin-film element according to claim 1, characterized in that the real part n and imaginary part k of the material of at least one of the two absorber layers differ in the entire visible spectral range by a factor of 5 or more, by a factor of 8 or more, by a factor of 10 or more or by a factor of 15 or more.

5. The thin-film element according to claim 1, characterized in that one of the absorber layers or both absorber layers are formed from silver.

6. The thin-film element according to claim 1, characterized in that one of the absorber layers or both absorber layers are formed from aluminum.

7. The thin-film element according to claim 1, characterized in that the interference layer structure is a symmetrical three-layer structure comprising a first absorber layer, a dielectric spacing layer and a second absorber layer.

8. The thin-film element according to claim 1, characterized in that the interference layer structure is an asymmetrical three-layer structure comprising a first absorber layer composed of a first material, a dielectric spacing layer, and a second absorber layer composed of a second, different material.

9. The thin-film element according to claim 1, characterized in that the dielectric spacing layer is formed from SiO_x or MgF₂.

10. The thin-film element according to claim 1, characterized in that, in transmitted light, the thin-film element exhibits, specified in the CIELAB color space, a chroma C*_ab of more than 20, preferably of more than 25.

11. The thin-film element according to claim 1, characterized in that, when viewed vertically, the thin-film element

appears green in transmitted light and exhibits a chroma C*_ab of more than 30, preferably of more than 40, or

appears yellow in transmitted light and preferably exhibits a chroma C*_ab of more than 20, or

appears red in transmitted light and exhibits a chroma C*_ab of more than 20, preferably of more than 30, or

appears blue in transmitted light and exhibits a chroma C*_ab of more than 20, preferably of more than 30.

12. The thin-film element according to claim 1, characterized in that the thin-film element appears colored in transmitted light and exhibits a color-shift effect.

13. The thin-film element according to claim 1, characterized in that the thin-film element appears colored in transmitted light and, when tilted, is substantially color constant with a changed chroma C*_ab.

14. The thin-film element according to claim 1, characterized in that the thin-film element is combined with a color filter, preferably a colored printing layer or a colored vapor deposition layer.

15. The thin-film element according to claim 14, characterized in that, in a predetermined viewing direction, the thin-film element and the color filter transmit only complementary colors.

16. The thin-film element according to claim 1, characterized in that the thin-film element is present in the form of patterns, characters or a code.

17. The thin-film element according to claim 1, characterized in that the thin-film element is combined with a relief structure, especially is applied to a diffractive relief structure or a microoptical relief structure.

18. A see-through security element for security papers, value documents and the like, comprising a support and, applied to the support, the thin-film element according to claim 1.

19. The see-through security element according to claim 18, characterized in that the thin-film element is applied to the support in the form of a motif.

20. The see-through security element according to claim 18, characterized in that the thin-film element is provided, on its top opposite the support, with an ink absorption layer.

21. An optically variable color pigment for a printing ink, wherein the pigment is formed by the thin-film element according to claim 1.

22. A data carrier comprising the thin-film element according to claim 1 or a see-through security element comprising a support and, applied to the support, the thin-film element;

in which the thin-film element or the see-through security element is arranged in or over a transparent window region or a through opening in the data carrier.

23. A data carrier comprising the thin-film element according to claim 1 or a see-through security element comprising a support and, applied to the support, the thin-film element;

in which the thin-film element or the see-through security element is embedded in the data carrier, especially in that the data carrier includes a paper substrate in which the thin-film element or the see-through security element is embedded.

24. The data carrier according to claim 22, characterized in that the data carrier is a value document, such as a banknote, especially a paper banknote, a polymer banknote, a foil composite banknote, or identification card.

25. The data carrier according to claim 23, characterized in that the data carrier is a value document, such as a banknote, especially a paper banknote, a polymer banknote, a foil composite banknote, or identification card.