Patent ID: 7118202

Claim:
An ink jet printhead comprising: a plurality of nozzles formed on a wafer substrate by lithographic etching and deposition techniques, each of the nozzles having a chamber for holding ejectable liquid, an ejection aperture in one wall of the chamber, and inlet for the ejectable liquid formed in a wall opposing that of the ejection aperture, a heater element suspended in the chamber for thermal contact with the ejectable liquid, the heater element having a planar structure configured parallel to that of the ejection aperture; drive circuitry corresponding to each of the nozzles for controlling the operation of the heater element; such that, heating the heater element to a temperature above the boiling point of the ejectable liquid forms a gas bubble that causes the ejection of a drop of the ejectable liquid through the ejection aperture corresponding to that heater element; wherein, the drive circuitry is formed in an area of the wafer substrate, the area having a centre point that is offset from a center point of the corresponding ejection aperture by less than 200 microns.