FIELD ACTIVATED SECURITY THREAD INCLUDING POLYMER DISPERSED LIQUID CRYSTAL

摘要

In a first aspect of this invention there is provided a security thread (1) which has an electrically actuated optical switch having a layer of polymer dispersed within a liquid crystal (10 and 12). The liquid crystal material has a visual characteristic that is switched between two states as a function of the presence or absence of an electric field. A second aspect of this invention provides a document or currency that has a paper matrix (11) including such a security thread. A third aspect of the invention provides a device for verifying the authenticity of a document or currency including the security thread. The device includes a first and second electrode (18 and 20), at least one of which is transparent. These electrodes function to create the electric field which activates the liquid crystal material.