Patent ID: 7341332

Claim:
An ink-jet printhead comprising: a substrate in which a space portion is formed; a passage plate installed on the substrate in which an ink chamber is formed to store ink; a nozzle plate installed on a top surface of the passage plate and formed with a nozzle through which the ink is ejected; and a vibration plate disposed between the substrate and the passage plate to generate a pressure to eject the ink by changing a volume of the ink chamber, the vibration plate comprising: a base layer formed on a top surface of the substrate so as to cover at least a part of the space portion, a thin film shape memory alloy layer which contacts the ink contained in the ink chamber and varies according to a temperature variation, a heating element disposed between the base layer and the thin film shape memory alloy layer and generates heat corresponding to the temperature variation, and an insulating layer disposed between the heating element and the thin film shape memory alloy layer to transfer the heat generated by the heating element to the thin film shape memory alloy layer, wherein the base layer has a residual compressive stress which resists flattening of the vibration plate.