Security paper with authenticity features in the form of substances luminescing only in the invisible region of the optical spectrum and process for testing the same

• US 4,451,521 A
• Filed: 10/23/1981
• Issued: 05/29/1984
• Est. Priority Date: 05/30/1980
• Status: Expired due to Term

• Current Assignee: GAO Gesellschaft Fur Automation und Organisation mbH
• Original Assignee: GAO Gesellschaft Fur Automation und Organisation mbH
• Inventors: Kaule, Wittich, Stenzel, Gerhard
• Primary Examiner(s): Ives, P.
• Application Number:
  US06/314,842
• Time in Patent Office: 949 Days
• Field of Search: 428/403, 428/438, 428/464, 428/900, 428/913, 428/917, 428/918, 428/915, 428/690, 428/537, 428/323, 428/333, 428/199, 428/204, 428/207
• US Class Current: 428/199
• CPC Class Codes: B41M 3/144 using fluorescent, luminescent or iridescent effects
• CPC Class Codes: B42D 25/382 absorbing or reflecting infrared light
• CPC Class Codes: B42D 25/387 absorbing or reflecting ultraviolet light
• CPC Class Codes: C09K 11/7769 Oxides C09K11/7768 takes precedence
• CPC Class Codes: C09K 11/7776 Vanadates; Chromates; Molybdates; Tungstates
• CPC Class Codes: D21H 21/48 Elements suited for physical verification, e.g. by irradiation
• CPC Class Codes: G06K 19/14 the marking being sensed by radiation
• CPC Class Codes: G07D 7/12 Visible light, infrared or ultraviolet radiation
• CPC Class Codes: Y10S 101/46 Printing operation controlled by code indicia on printing plate or substate
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10S 428/908 Impression retention layer, e.g. print matrix, sound record
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/24835 including developable image or soluble portion in coating or impregnation [e.g., safety paper, etc.]
• CPC Class Codes: Y10T 428/24876 Intermediate layer contains particulate material [e.g., pigment, etc.]
• CPC Class Codes: Y10T 428/24901 including coloring matter
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/261 In terms of molecular thickness or light wave length
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/31634 Next to cellulosic
• CPC Class Codes: Y10T 428/31703 Next to cellulosic
• CPC Class Codes: Y10T 428/31996 : Next to layer of metal salt [e.g., plasterboard, etc.]

Abstract

Security paper with luminescing authenticity characteristics which after excitation with invisible light emit exclusively invisible light of different wavelengths as authenticity signal. The luminophores can be included in the printing ink used or they can be added to the paper material in the manufacture of the paper material. A corresponding test apparatus makes it possible to check the authenticity of the security paper in the presence of customers but unnoticed by them; thereby the invisibility of the test signal and the authenticity signal are taken advantage of and the test device is hidden behind a plate non-transmissive for visible light which however is transmissive for the test signal and for the authenticity signal.

Claims

1. Security document with authenticity characteristics comprising:

a substrate and a luminescing substance, wherein the luminescing substance is constructed to exhibit, when excited, luminescence emission only in the invisible region of the optical spectrum, said luminescing substance comprising a luminophore combined with an absorbing material having an absorption spectrum which includes a portion of the visible spectrum in which said luminophore emits radiation.

2. Security document according to claim 1, wherein the absorbing material is a pigment.

3. Security document according to claim 2, wherein the absorbing material is a dyestuff.

4. Security document according to claim 2, wherein the luminescing substance is a mixture of the luminophore and the absorbing material.

5. Security document according to claim 2, wherein the luminescing substance comprises a luminophore coated with the absorbing material.

6. Security document according to claim 2, wherein the luminescing substance comprises a luminophore layer coated with the absorbing material.

7. Security document according to claim 1, wherein the luminophore has a broad band emission spectrum which includes portions of the visible spectrum.

8. Security document according to claim 7, wherein the luminophore is an organic compound.

9. Security document according to claim 8, wherein the luminophore is a laser dyestuff.

21. Security document according to claim 1, wherein the luminescing substance is provided at least partially in large areas of the substrate.

22. Security document according to claim 1, wherein the luminescing substance is mixed into the substrate composition.

23. Security document according to claim 1, wherein the luminescing substance is present in the form of strips.

24. Security document according to claim 1, wherein the luminescing substance is present as an invisible layer at least partially covering the substrate.

25. Security document according to claim 1, wherein the luminescing substance on excitation with ultraviolet light luminesces in the ultraviolet region of the optical spectrum.

26. Security document according to claim 1, wherein the luminescing substance on excitation with ultraviolet light luminesces in the infrared region of the optical spectrum.

27. Security document according to claim 1, wherein the luminescing substance on excitation with infrared light luminesces in the ultraviolet region of the optical spectrum.

28. Security document according to claim 1, wherein the luminescing substance on excitation with infrared light luminesces in the infrared region of the optical spectrum.

10. Security document with authenticity features, comprising:

a substrate and a luminescing substance, wherein the luminescing substance is constructed to exhibit, when excited, luminescence emission only in the invisible region of the optical spectrum, said luminescing substance comprising a host matrix doped with a material from the group consisting of the rare earth metals and lanthanides of atomic number 58 to 71, wherein the absorption spectrum of the host matrix includes a portion of the visible spectrum and is such that in the visible region of the optical spectrum it absorbs strongly at least at those wave lengths at which the dopant luminesces and accordingly suppresses the undesired visible luminescences.

11. Security document according to claim 10, wherein the host matrix comprises as an element absorbing in the visible spectral region a metal of the sub-groups VI, VII or VIII.

12. Security document according to claim 10, wherein the dopant has an emission spectrum including portions of the visible spectrum.

13. Security document according to claim 10, wherein the host matrix has a perovskite structure according to the general formula AXO₃, wherein

A represents a material selected from the group consisting of:

bismuth, a rare earth metal, and a combination of bismuth and a rare earth metal, and

X represents one or more absorbing transition metals.

14. Security document according to claim 13, where X is selected from the group consisting of cobalt, nickel, and iron.

15. Security document according to claim 10, wherein the host matrix has a structure selected from the group consisting of:

a garnet structure, a perovskite structure and a ferrite structure.

16. Security document according to claim 15, wherein the garnet structure can be described by the general formula

17. Security document according to claim 15, wherein the garnet structure is described by the general formula

18. Security document according to claim 15, wherein the garnet structure is described by the general formula

19. Security document according to claim 15, wherein the garnet structure is described by the general formula

20. Security document according to claim 10, wherein the host matrix has a ferrite structure according to the general formula