US Patent 9436058 Electrophoretic display film for anti-counterfeit application

The present invention is directed to an electrophoretic display film which can be controlled to malfunction permanently within a period of time. It provides an elegant method to utilize an electrophoretic film for anti-counterfeit purposes. The concept involves the removal of strong barrier layer(s) from the film to allow the solvent in the electrophoretic fluid within the film to evaporate through weak barrier layer(s), and within a period of time, the performance of the display film will be significantly degraded and the film cannot be re-used.