Patent EA-001757-B1 (EA)
Title: Self-verifying security documents
Inventor: TAYLOR JOHN CHARLES
IPC: B44F1/12
Filed: 1997-10-08
Abstract: 1. A security document, such as a banknote, comprising a single flexible sheet formed from a substrate bearing indicia, said sheet having a first portion of transparent plastics material, and a security device provided at a second portion of the sheet spaced laterally from the transparent first portion, wherein the transparent first portion includes self verification means to verify or inspect the security device when the sheet is bent, folded or twisted to bring the first and second portions into register with one another. 2. A security document according to claim 1 wherein the sheet is formed from a transparent plastics substrate to which at least one opacifying layer is applied. 3. A security document according to claim 2 wherein said at least one opacifying layer only partially covers the surface of the substrate to leave at least said first portion essentially indicia-free. 4. A security document according to claim 2 or claim 3 wherein the at least one opacifying layer comprises a coating of opacifying ink applied to the transparent plastics substrate. 5. A security document according to any one of claims 1 to 4 wherein the flexible sheet is generally rectangular and the first and second portions are so disposed that folding of the sheet about a centre line brings the first and second portions into register. 6. A security document according to any one of claims 1 to 5 wherein the sheet is oblong having a major axis and a minor axis and the first and second portions are so disposed that folding of the sheet about a line coincident with or parallel to the major axis or the minor axis brings the first and second portions into register. 7. A security document according to any one of claims 1 to 4 wherein the flexible sheet is generally rectangular and the first and second portions are so disposed that folding of the sheet about a diagonal axis brings the first and second portions into register. 8. A security document according to any one of claims 1 to 4 wherein the flexible sheet is able to be rolled to form a cylinder and the first and second portions are so disposed that rolling of the flexible sheet into a cylinder brings the first and second portions into register. 9. A security document according to any one of claims 1 to 8 wherein the selfverification means of the first portion comprises an optical lens and the security device provided at the second portion comprises a feature which can be inspected, enhanced or optically varied by the optical lens when the first and second portions are brought into register. 10. A security document according to claim 9 wherein the optical lens is a magnifying lens. 11. A security document according to claim 10 wherein the security device comprises an area of microprinting, a small image or a fine line or filigree pattern. 12. A security document according to claim 9 wherein the optical lens is a distorting lens. 13. A security document according to claim 12 wherein the security device comprises a feature or image which is distorted by the distorting lens when the first and second portions are brought into register. 14. A security document according to claim 12 wherein the security device comprises a distorted feature or image which is corrected by the distorting lens when the first and second portions are brought into register. 15. A security document according to any one of claims 9 to 14 wherein the optical lens is formed by embossing, engraving or otherwise deforming the first portion of transparent plastics material with a series of lines. 16. A security document according to any one of claims 9 to 14 wherein the optical lens is formed by applying a curable varnish or coating to the first portion of transparent plastics material. 17. A security document according to any one of claims 1 to 8 wherein the security device comprises an area of the sheet printed with metameric inks, and the self verification means comprises an optical filter for viewing the area printed with metameric inks. 18. A security document comprising a sheet formed from a substrate bearing indicia, said sheet having an essentially indicia-free portion of transparent plastics material, wherein the transparent, essentially indicia-free portion includes a colour tinted optical filter for viewing an area printed with metameric inks on the same, for viewing similar area, or a different security document  19. A security document according to claim 17 or claim 18 wherein the optical filter is arranged to create a restricted or altered wavelength environment to reveal colour changing properties of the area printed with metameric inks. 20. A security document according to any one of claims 17 to 19 wherein the optical filter is produced by including pigments with a polymer in the production of a plastics film substrate to colour tint the substrate. 21. A security document according to any one of claims 17 to 19 wherein the optical filter is formed by applying a tinted varnish or coating over the transparent portion. 22. A security document according to any one of claims 1 to 8 wherein the selfverification means comprises a first polarising transparent window and the security device comprises a second polarising transparent window. 23. A security document comprising a flexible sheet formed from a substrate bearing indicia, said sheet having an essentially indicia-free window of transparent plastics material with polarisation characteristics for verifying a second transparent polarising window at another location on the same or a different security document. 24. A security document according to claim 22 or claim 23 wherein the first transparent polarising window has a first plane polarisation axis and the second transparent polarising window has a second plane polarisation axis and the windows are disposed so that when the windows are brought into register the intensity of light transmitted through the windows is reduced. 25. A security document according to any one of claims 22 to 24 wherein the portion of the sheet including the first polarising window is able to be twisted or rotated relative to the second polarising window to vary the intensity of light transmitted through the polarising windows when they are in register. 26. A security document according to any one of claims 22 to 25 wherein the or each polarising window is formed by stretching the transparent plastics substrate in one direction during manufacture. 27. A security document according to any one of claims 22 to 25 wherein the transparent plastics substrate includes liquid crystals to form the polarising window or windows. 28. A security document according to any one of claims 22 to 25 wherein a coating containing liquid crystals is applied to at least one transparent, essentially indicia-free portion of the sheet to form a polarising window. 29. A security document according to any one of claims 1 to 8 wherein the selfverifying means comprises a feature including a first set of lines and the security device comprises a feature including a second set of lines, wherein an interference effect is produced when the security document is bent or folded to bring the self-verifying means and the security device into register. 30. A security document according to claim 29 wherein the self-verifying means and the security device are Moire inducing patterns. 31. A security document according to claim 29 or claim 30 wherein the selfverifying means and the security device are arranged at transversely spaced locations of the sheet such that when the sheet is folded over itself to bring the self verifying means and the security device into register, the second set of lines is inclined to the first set of lines. 32. A security document according to any one of claims 29 to 31 wherein the first and second sets of lines are printed on the first and second portions of the sheet. wherein the method comprises 33. A security document according to any one of claims 29 to 31 wherein the first and second sets of lines are embossed or engraved on the first and second portions of the sheet. 34. A security document according to any one of claims 1 to 9 wherein the self verifying means comprises a first part of an image and the security device comprises a second part of an image, said first and second parts together forming a complete image when the flexible sheet is bent, folded or twisted over itself to bring the first and second portions into register. 35. A security document according to claim 34 wherein the second part of the image is provided on a transparent window. 36. A security document according to claim 34 wherein the second part of the image is hidden by an opacifying coating in reflected light by visible in transmitted light. 37. A security document according to any one of claims 34 to 36 wherein the first and second parts of the image are printed on the first and second portions of the sheet. 38. A security document according to any one of claims 34 to 36 wherein the first and second parts of the image are embossed or engraved on the first and second portions of the sheet. 39. A method of verifying a security document in accordance with any one of claims 1 to 38 wherein the method comprises bringing selfverification means into register with the security means. 40. A method of verifying a security document in accordance with claim 39 wherein the method comprises the step of bending, folding or twisting. 41. A method of verifying a security document in accordance with claim 39 wherein the method comprises bringing selfverification means into register with the security device provided at the second portion of the sheet.