| 摘要 |
A security device (10) for security substrates, such as paper, used for making security documents, such as bank notes, has anti-counterfeitable features. The security device comprises a first opaque layer (14) and a second opaque layer (15), said opaque layers each having a plurality of clear regions (18,19). A first fluorescent layer (16) is positioned between the first and second opaque layers and a second fluorescent layer (17) is positioned which is separated from the first fluorescent layer by one of the opaque layers. The first and second fluorescent layers exhibit different visible colours under ultraviolet light. The clear regions (18) in the first opaque layer form indicia and the clear regions (19) in the second opaque layer overlap with only some of the clear regions in the first opaque layer such that only a portion of the indicia are visible in transmitted light. |
