Abstract: An electrophoretic device defining a fluid tight assembled container filled with a suspension of solid electrically charged particles. Two outer plates of the container are provided with electrodes and part of the inner walls of the container and electrodes are coated with an electret layer that is a layer of dielectric material carrying permanent electrical charges. The electret layer coating one of the outer plates may be removable in order to allow the transfer of the solid electrically charged particles between different electrophoretic media. One of the outer plate may be either transparent allowing thus a presentation of data. The permanent electrical charges of the electret layer introduce a voltage treshold into the control of migration of the suspended particles in the electrophoretic medium.

Abstract: An information display device utilizing the phenomenon of electrophoresis. It comprises two transparent electrodes parallel to one another and assembled in order to constitute a sealed cell filled with a colored fluid, and a thin porous diaphragm scattering the light in a color differing from that of the fluid, the diaphragm being arranged in the vessel parallel to the electrodes. The diaphragm displaces by electrophoresis, from one electrode to the other, under the action of potential differences applied to the electrodes.