Patent ID: 7172270

Claim:
An ink jet printhead comprising: a plurality of nozzles; a bubble forming chamber corresponding to each of the nozzles; and a heater associated with each of the nozzles respectively, the heater having a planar structure with a heater element connected to electrodes, the heater element being suspended by the electrodes in the bubble forming chamber for thermal contact with a bubble forming liquid, such that the plane of the heater is parallel to the nozzle; wherein during use, the bubble forming chamber receives a supply of an ejectable liquid at an ambient temperature, and energy is applied to the heater element through the electrodes to heat the bubble forming liquid until a gas bubble forms that encircles at least some of the heater element, the gas bubble causing a drop of the ejectable liquid to eject through the nozzle, the energy applied to the heater element being less than the energy required to heat a volume of the ejectable liquid equal to the volume of the drop, from a temperature equal to the ambient temperature to the boiling point of the bubble forming liquid.