Patent ID: 6315398
Filing Date: 2001-11-13
Classification: B41J

Abstract:
A heater element for use in a printhead of a printing system to expel ink onto a recording medium by expansion and collapse of a vapor bubble comprising:a substrate;a resistive layer formed over said substrate, the resistive layer having contact regions;contact means for contacting said resistive layer at the contact regions;insulation means for electrically isolating and chemically protecting the resistive layer and formed over said resistive layer, said insulation means forming a bottom wall of a pit and protecting said resistive layer from corrosion caused by the ink;a first insulative film formed over the contact means and first edge portions of the insulation means; anda second insulative film formed over at least a portion of the first insulative film and at least a second edge portion of the insulation means, said second insulative film having at least one inner wall and a top surface, both said at least one inner wall and said top surface being exposed to the ink, said at least one inner wall forming a side wall of the pit and extending to the bottom wall of said pit, said top surface defining a lower surface of an ink channel, said pit being formed directly above said resistive layer and exposing a surface of said insulation means for transferring energy generated by said resistive layer to the ink, said second insulative film inner wall protecting the first insulative film from erosion by cavitational pressures generated in the pit during collapse of the vapor bubble.