Patent ID: 7597423

Claim:
A printhead integrated circuit for an inkjet printer, the printhead integrated circuit comprising: a wafer substrate; a plurality of nozzles formed on a surface of the wafer substrate, each nozzle having a nozzle aperture and at least one heater element respectively; fluid flow paths for establishing fluid communication between the nozzle aperture and a supply of ejectable liquid such that during use, the heater element of each nozzle is in thermal contact with the ejectable liquid; and drive circuitry formed on the wafer substrate, the drive circuitry being connected to each of the heater elements such that, in response to a drive signal from the drive circuitry, each of the heater elements heat the ejectable liquid to a temperature above its boiling point to form a gas bubble that ejects a drop of ejectable liquid through the nozzle aperture; wherein, the plurality of nozzles have an areal density exceeding 40,000 nozzles per square cm of the surface of the wafer substrate.