Patent ID: 7192119

Claim:
A printhead nozzle arrangement which comprises a substrate; drive circuitry positioned on the substrate; a nozzle chamber structure arranged on the substrate, defining a nozzle chamber in fluid communication with a supply of ink and an ink ejection port in fluid communication with the nozzle chamber; and an actuator that is connected to the drive circuitry and is operatively positioned with respect to the nozzle chamber, the actuator being reciprocally deformable between a quiescent condition and an active condition to eject ink from the ink ejection port, wherein the actuator comprises a shape memory alloy sandwiched between a first structural layer and a second structural layer, the second structural layer being mechanically locked to the first structural layer to provide a stress reference for the first structural layer, and wherein the shape memory alloy is in a pre-stressed martensitic phase when the actuator is in the quiescent condition and in an austenitic phase when the actuator is in the active condition, such that cyclic phase changes generate said reciprocal movement.