US Patent 7128400 Very high efficiency thermal ink jet printhead

There is disclosed an ink jet printhead which comprises a plurality of nozzles and one or more heater elements corresponding to each nozzle. Each heater element is configured to heat a bubble forming liquid in the printhead to a temperature above its boiling point to form a gas bubble therein. The generation of the bubble causes the ejection of a drop of an ejectable liquid (such as ink) through an ejection aperture in each nozzle, to effect printing. In each nozzle, less than 200 nanoJoules of energy is transferred to the heater element in order to form the gas bubble that causes the ejection of the drop of ejectable liquid. This configuration provides for very efficient operation.