An electro-optic picture display and memory device employs a material which has the property of field-induced ferroelectricity such as lanthanum-containing mixed crystals of lead zirconate and lead titanate. Remanent storage is achieved in that certain electrodes on the plate are separated from the signal...http://www.google.de/patents/US3990770?utm_source=gb-gplus-sharePatent US3990770 - Electro-optic picture display and memory device
