Security devices and methods for their manufacture

摘要: A security device comprises at least one cholesteric liquid crystal (LC) layer 3 disposed on a substrate 2, the LC collectively exhibiting an image I detectable by naked eye under non-polarised visible light illumination. The has respective pattern P of or more first regions 4 in which is ordered and thereby exhibits optically variable colour, alongside second 5 disordered substantially transparent colourless spectrum. combination patterns forms image. There also provided component comprising plurality curable layers (3a-c, Fig, 2b) substrate, each formed different radiation material wherein when viewed predetermined viewing angle, colour exhibited from that other layer(s). Some radiation-curable materials comprise photoinitiators are responsive to wavelengths radiation.