| 摘要 |
IDENTIFICATION OF ARTICLES An identifiable article, especially an identity document, has a marked element (8), eg. a photograph, covered by a mask (2) which is normally opaque but which, upon application of a suitab1e electric field, changes to an at least translucent state. Preferably, the mask (2) comprises a liquid-crystal layer (6) sandwiched between two plates (5, 7) of which at least one plate is at least translucent. |
