| 摘要 |
A security device ( 3 ) and a method of forming a security device ( 3 ) is provided in which a sheet ( 1 ) has a substantially transparent or translucent layer ( 10 ) and a reflective layer ( 11 ) with at least part of the reflective layer ( 11 ) being visible through the transparent or translucent layer ( 10 ) from a first side of the sheet ( 1 ). The sheet ( 1 ) is blind embossed from the first side through the transparent or translucent layer ( 10 ) and onto the reflective layer ( 11 ) to form a transitory embossed image ( 3 ). The transitory embossed image ( 3 ) may be provided in a window or half-window ( 2 ) formed by applying one or more opacifying layers ( 14 ) to the substrate ( 10 ) except in the area containing the reflective layer ( 11 ) and transitory embossed image ( 3 ) on one or both sides of the substrate ( 10 ). In one embodiment, the reflective layer is a highly reflective metallic ink ( 11 ). In another embodiment, the reflective layer is an optically variable pigment ( 11 a) which provides a colour shift between two distinct colours with the colour shift dependent upon viewing angle. In further embodiments, the transitory embossed image ( 41, 42, 43 ) comprises macro-embossings ( 52, 53 ) with micro-embossings ( 54, 55 ) formed on the sides of the macro-embossings ( 52, 53 ). Each of the embodiments of transitory embossed images produces unusual visual switching effects which cannot be reproduced by photocopying and which are difficult to counterfeit. |
