Patent ID: 6226127
Filing Date: 2001-05-01
Classification: G02B,G09F

Abstract:
A substrate which is arranged to provide an optically variable image to a viewer, said image being composed of a plurality of pixels, the substrate having a front surface which is formed with a plurality of groups of elemental areas, with different said groups of elemental areas corresponding to respective pixels of said image, and the different elemental areas of each group being formed with respective grooves or ridges or with respective sets of grooves or ridges, the grooves or ridges of different elemental areas of each group being at different orientations within the plane of said substrate so that, at different orientations of the substrate within said plane, different elemental areas of each said group of elemental areas contribute to the respective pixel of the image seen by the viewer, with said grooves or ridges being arranged to direct light to the viewer at predetermined angles relative to the plane of said substrate, by reflecting light incident on said front surface, without interference occurring between light rays directed to the viewer from the substrate.