Thermal, drop-on-demand, ink jet print cartridge

Claim 1

A thermal drop-on-demand, ink jet printing assembly comprising: (a) a plastic base member having molded therein an ink inlet aperture, a heater slit and a plurality of ink supply channel recesses between said inlet aperture and said slit; (b) an electroformed cover member mounted on said base member, said cover member having a planar surface which covers said channel recesses to define ink passages from said inlet aperture to said heater slit and orifice means formed at a location over said heater slit; and (c) a heater/electrode chip including: (i) a ceramic support having an edge surface formed with a series of land and groove portions and two side surfaces extending approximately normally away from said edge surface; (ii) a plurality of planar resistor elements formed on the groove bottoms of said edge surface; and (iii) address and common electrode means respectively formed on said side surfaces and coupled to opposite edge portions of said resistor elements; said heater/electrode chip being mounted in said slit of said base member so that said resistor elements are centered with respect orifices of said cover member, so that the land tops of said edge surface are intermediate respective orifices and so that said electrode means extend generally normally away from said array of orifice.