Abstract: A self-verifying security document, such as a banknote, comprises a flexible sheet formed from a plastics substrate bearing indicia. The sheet has a window of transparent plastics material which includes self-verification means for verifying a security device provided at a laterally spaced second portion of the sheet when the sheet is bent or folded to bring the window into register with the security device. The self-verification means may be an optical lens for reading an area of microprinting. In another embodiment, the self-verification means may be an optical filter for viewing an area printed with metameric inks. In other embodiments, the self-verification means and the security device may be polarizing windows or Moire inducing patterns.

Abstract: A method of marking or forming a transparent window in an article 6, such as a security document, is provided in which areas of opacifying layers of printed ink 8, 10 on opposite surfaces of a polymeric film or substrate 12 are irradiated by laser radiation 4 of a selected wavelength. The opacifying layers 8, 10 have greater absorption characteristics for the laser radiation than the film or substrate 12 which is substantially transparent to the selected wavelength of the laser radiation so that after ablation of the area of printed matter 8 on one surface, the radiation passes through the substrate 12 substantially unaffected to ablate the area of printed matter 10 on the opposite surface. In the resultant article, the markings or windows formed by the areas of printing removed from each surface of the substrate 12 are in register, and provide a deterrent against counterfeiting.

Abstract: A security document (1), such as a bank note, is formed from a sheet-like substrate (10) of clear plastic material with layers (13, 14, 15, 16) of opacifying ink applied to the surfaces (11, 12) of the substrate (10). The security document (1) includes a security device (20) which is at least partially obscured by the layers (13, 14) of opacifying ink on a flat surface (11) of the substrate (10). The layers (15, 16) on the second surface (12) of the substrate (10) are applied in such a manner so as to leave a “half-window” area uncovered by opacifying ink through which the security device (20) is visible for one side of the document (1). The security device (20) may extend transversely outside the half-window area and be visible in transmission, enabling a different contrasting effect to be observed from both sides of the document.

Abstract: A self-verifying security document, such as a banknote (1) comprises a flexible sheet formed from a plastics substrate (2) bearing indicia (3). The sheet has a window (5) of transparent plastics material which includes self-verification means (11) for verifying a security device (4) provided at a laterally spaced second portion of the sheet when the sheet is bent or folded to bring the window (5) into register with the security device (4). The self-verification means may be an optical lens (11) for reading an area of microprinting (10). In another embodiment, the self-verification means may be an optical filter (21) for viewing an area (22) printed with metameric inks. In other embodiments, the self-verification means and the security device (4) may be polarizing windows (31, 32) or Moire inducing patterns (41, 42).

Abstract: A self-verifying security document, such as a banknote (1) comprises a flexible sheet formed from a plastics substrate (2) bearing indicia (3). The sheet bas a window (5) of transparent plastics material which includes self-verification means (11) for verifying a security device (4) provided at a laterally spaced second portion of the sheet when the sheet is bent or folded to bring the window (5) into register with the security device (4). The self-verification means may be an optical lens (11) for reading an area of microprinting (10). In another embodiment, the self-verification means may be an optical filter (21) for viewing an area (22) printed with metameric inks. In other embodiments, the self-verification means and the security device (4) may be polarising windows (31, 32) or Moire inducing patterns (41, 42).

Abstract: A self-verifying security document, such as a banknote (1) comprises a flexible sheet formed from a plastics substrate (2) bearing indicia (3). The sheet has a window (5) of transparent plastics material which includes self-verification means (11) for verifying a security device (4) provided at a laterally spaced second portion of the sheet when the sheet is bent or folded to bring the window (5) into register with the security device (4). The self-verification means may be an optical lens (11) for reading an area of microprinting (10). In another embodiment, the self-verification means may be an optical filter (21) for viewing an area (22) printed with metameric inks. In other embodiments, the self-verification means and the security device (4) may be polarising windows (31, 32) or Moire inducing patterns (41, 42).