Speed electrocoagulation printing method and apparatus

An apparatus for reproducing an image and transferring same onto a substrate, which comprises:

• a positive cylindrical electrode having a central longitudinal axis and a passivated surface defining a positive electrode active surface, said positive electrode being formed of an electrolytically inert metal;
• means for rotating said positive electrode about the longitudinal axis thereof at a substantially constant speed;
• a plurality of negative electrolytically inert electrodes electrically insulated from one another and arranged in rectilinear alignment to define a series of corresponding negative electrode active surfaces disposed in a plane parallel to the longitudinal axis of said positive electrode and spaced from the positive electrode active surface by a constant predetermined gap, said negative electrodes being spaced from one another by a distance at least equal to said electrode gap to prevent edge corrosion of said negative electrodes;
• means for coating the positive electrode active surface with an olefinic substance and a metal oxide to form on said surface micro-droplets of olefinic substance containing said metal oxide in an amount to prevent corrosion of said positive electrode;
• means for filling said electrode gap with a substantially liquid colloidal dispersion containing an electrolytically coagulable colloid, a liquid dispersing medium, a soluble electrolyte and a coloring agent, and having a substantially constant temperature;
• means for electrically energizing selected ones of said negative electrodes to cause point-by-point selective coagulation and adherence of the colloid onto the olefin and metal oxide-coated positive electrode active surface opposite the electrode active surfaces of said energized negative electrodes while said positive electrode is rotating, thereby forming a series of corresponding dots of colored, coagulated colloid representative of a desired image;
• means for removing any remaining non-coagulated colloid from said positive electrode active surface;
• and
• means for bringing a substrate into contact with the dots of colored, coagulated colloid at a transfer station to cause transfer of the colored, coagulated colloid onto said substrate and thereby imprint said substrate with said image.