Patent ID: 7303263

Claim:
An ink jet printhead comprising: a substrate having a substrate surface; a plurality of nozzles, each nozzle having a nozzle aperture opening through the substrate surface, the areal density of the nozzles relative to the substrate surface exceeding 40,000 nozzles per square cm of substrate surface; at least one respective heater element corresponding to each nozzle, and, CMOS drive circuitry layers deposited such that the heater element is positioned between the CMOS and the nozzle, the CMOS drive circuitry being in electrical contact with each of the heater elements respectively; wherein each heater element is arranged for being in thermal contact with a bubble forming liquid, and each heater element is configured to heat at least part of the bubble forming liquid to a temperature above its boiling point to form a gas bubble therein thereby to cause the ejection of a drop of the bubble forming liquid through the nozzle corresponding to that heater element.