Device for direct electrostatic printing (DEP) comprising rows of smaller and larger sized apparatus

摘要

A device for use in the technique of direct electrostatic printing (DEP) on an intermediate or final substrate is described, comprising: a receiving member support 5 a printhead structure 6 having control electrodes 6a on its back side, in combination with apertures 7 and at least one common shield electrode 6b on the front side ; a toner delivery means 1 presenting a cloud 4 of toner particles in the vicinity of the apertures 7. The printhead structure 6 is made of a plastic isolating substrate, and has at least two rows of apertures. Preferentially each row has one common shield electrode (6b, 6c) at the front side of the printhead structure. The individual control electrodes on the back side are galvanically isolated per aperture from each other and from each shield electrode. The control electrodes are arranged around the apertures. The size or diameter of the apertures of one row is substantially different from the size of the apertures of a second row. This arrangement allows a high quality reproduction of continuous tone images, along with crisp graphics and characters by one single printing pass.