Patent ID: 7222943

Claim:
An ink jet printhead comprising: a structure with a nozzle plate defining a plurality of nozzles, and chamber walls extending generally perpendicular to the nozzle plate, the structure formed on an underlying substrate having at least one heater element corresponding to each of the nozzles respectively such that the structure and the underlying substrate define a chamber corresponding to each of the nozzles; the heater elements being configured for thermal contact with a bubble forming liquid for heating at least part of the bubble forming liquid to a temperature above its boiling point to form a gas bubble therein to eject a drop of the liquid through the nozzle corresponding to the heater elements; wherein, the structure is a one piece element with the chamber walls being integrally formed with the nozzle plate and the nozzle plate thickness and the chamber wall depth being selected so as to keep deformation of the substrate and the structure, caused by differential thermal expansion during known fabrication temperature variations, below a predetermined limit.