Article and security device based on customised microprism film

摘要

A security device comprises at least two regions, each region comprising a prismatic surface structure defining an array of substantially planar facets. Each region forms a reflector due to total internal reflection when viewed at least one first viewing angle and is transparent when viewed at at least one second viewing angle. The said at least one first viewing angle of one region is different from the at least one first viewing angle of the other region.