Abstract: An ink drop ejecting printhead includes a substrate having an ink drop emitting opening; a heater on the substrate surrounding the opening; and an ink supply communicating with the opening to supply ink, whose surface tension decreases inversely with its temperature, to the opening under positive pressure relative to ambient. A variable-energy electrical power supply connected to the heater, whereby application of an electrical pulse of sufficient energy to the heater will cause separation of an associated ink drop from the ink supply. A power supply control is adapted to regulate the energy of electrical pulses applied to the heater from the power supply, whereby the volumes of separated ink drops are proportional to the energy of the associated electrical pulses.

Abstract: A liquid ink, drop on demand page-width printhead comprises a semiconductor substrate, a plurality of drop-emitter nozzles fabricated on the substrate; an ink supply manifold coupled to the nozzles; pressure means for subjecting ink in the manifold to a pressure above ambient pressure causing a meniscus to form in each nozzle; a means for applying heat to the perimeter of the meniscus in predetermined selectively addressed nozzles; a means for controlling the volume of poised drops in the selectively addressed nozzles; and a means for transferrring the poised drops onto the recording media.