U.S. Pat. No. 3,647,291, Pressman et al describes a printing form which essentially includes a dielectric having electrodes associated therewith. An ion source and an optical system, controlled by the image, generates a corresponding charge image on the surface of the printing form. Charged toner particles are then accepted on the charged image surface in accordance with the original image. Toner is then transferred from the printing form to the substrate by contact. The charge on the printing form is neutralized upon acceptance of the toner, and thus the printing form must be again programmed with the image before it can carry out a new printing operation. The charge image, thus, must be refreshed or newly generated after each transfer of toner.
U.S. Pat. No. 4,833,990, Hirt and Fuhrmann, claiming priority of German 36 44 758, describes the use of ferroelectric materials in printing machines. The disclosure is specifically directed to offset printing machines using inks conventional in offset printing, that is, oil-based inks in combination with damping liquids, typically water. The system uses the characteristics of ferroelectric material that differentially polarized localities of the ferroelectric material have differential affinity for oil and water. Polarized parts are hydrophilic and accept water, whereas depolarized materials are hydrophobic, so that they can accept printing ink.
USPTO Backgrounds
USPTO Backgrounds