Security document and method for its manufacture

Abstract

A security document is disclosed, comprising: a transparent or translucent polymeric substrate; one or more opacifying layers disposed on the first and / or second sides of the transparent or translucent polymeric substrate, the one or more opacifying layers defining a substrate window region across which at least one of the one or more opacifying layers is absent; and, across at least part of the substrate window region, an array of image elements and an overlapping array of focussing elements are provided. The array of image elements is located substantially in the focal plane of the focussing elements. The array of image elements comprises one or more sets of image elements predominantly or wholly having substantially the same visual appearance as the collective visual appearance of the one or more opacifying layers at a selected location on the security document. The or each set of image elements is arranged at a periodicity substantially matched to that of the array of focussing elements in at least one dimension and defines a respective window cover image. The array of focusing elements are configured to direct light from selected ones of the array of image elements in dependence on the viewing angle, the or each window cover image being displayed by the corresponding set of image elements in combination across the at least part of the substrate window region within a respective range of viewing angles. The security document exhibits an apparent window region formed by the substrate window region in combination with any one of the one or more window cover images that is displayed depending on the viewing angle, such that upon changing the viewing angle, the apparent window region appears to change and / or disappear.

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