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|1. (WO2017149284) SECURITY ELEMENTS AND SECURITY DOCUMENTS|
|Applicants:||DE LA RUE INTERNATIONAL LIMITED
|Inventors:||HOLMES, Brian William
SNELLING, James Peter
|Title:||SECURITY ELEMENTS AND SECURITY DOCUMENTS|
A security element, comprising: a colourshifting film which, when viewed in reflected or transmitted light, exhibits different colours in dependence on the viewing angle and which, when viewed at any one angle, exhibits first and second colours when viewed in reflected and transmitted white light respectively, the first and second colours being complementary, the colourshifting film comprising a plurality of polymer layers arranged in a periodic stack, including respective layers of at least first and second polymer materials having different refractive indices from one another; and a light absorbing material layer underlying the colourshifting film, the light absorbing material layer having one or more gaps therein so as to define a pattern. At any one viewing angle θ, the percentage of incident light reflected by the colourshifting film varies in dependence on its wavelength according to a function Rθ(λ) having a maximum at a peak wavelength λΒ,θ=0, and the colourshifting film is configured such that, at least at a viewing position lying on the normal to the security element, the percentage RΒ,θ=0 of incident light at the peak wavelength AΒ,θ=0 that is reflected by the colourshifting film is at least 60%, and the maximum of the function Rθ(λ) has a bandwidth (Δλθ=ο) of 150 nm or less. The security element is substantially transparent or translucent to at least some wavelengths of visible light at the locations corresponding to the one or more gaps in the light absorbing material layer, such that in the locations corresponding to the one or more gaps in the light absorbing material layer, the security element exhibits different respective colours when viewed in reflected white light and when viewed in transmitted white light at the same viewing angle.