Electrocoagulation printing method and apparatus providing enhanced image resolution

摘要

An image is reproduced and transferred onto a substrate by (a) providing a positive electrode having a continuous passivated surface moving at constant speed; (b) forming on the positive electrode surface dots of colored, coagulated colloid representative of a desired image, by electrocoagulation of a colloid present in an electrocoagulation printing ink; and (c) bringing a substrate into contact with the dots of colloid to cause transfer of same onto the substrate. Step (b) is carried out by providing a series of negative electrodes having passivated surfaces spaced from the positive electrode surface by a constant gap; coating the positive electrode surface with an olefin; filling the electrode gap with the ink; applying to the negative electrodes a pulsed bias voltage; and applying to selected ones of the negative electrodes a trigger voltage sufficient to cause point-by-point selective coagulation and adherence of the colloid onto the olefin-coated positive electrode surface.