Abstract: Apparatus for pattern generation on a dielectric substrate including a drum having an outer pattern receiving and retaining dielectric substrate, a plurality of electrodes mounted in the drum and being arranged so as to underlie the outer pattern receiving and retaining dielectric substrate, imagewise voltage supply circuitry for imagewise application of voltage to the plurality of electrodes, and an elongate ion source operative to apply a flow of charges to the dielectric substrate in a non-imagewise manner.