| 摘要 |
PCT No. PCT/GB82/00001 Sec. 371 Date Aug. 24, 1982 Sec. 102(e) Date Aug. 24, 1982 PCT Filed Jan. 4, 1982 PCT Pub. No. WO82/02445 PCT Pub. Date Jul. 22, 1982.An identification article, especially an identity document, has a marked element (8), e.g. a photograph covered by a mask (2) which is normally opaque but which, upon application of a suitable electric field changes to an at least translucent state. Preferably the mask (2) complies a liquid crystal layer (16) sandwiched between two plates (5 and 7) of which one plate is at least translucent. |
