Patent ID: 6527372
Filing Date: 2003-03-04
Classification: B41J

Abstract:
A method for optimizing a driving input signal in an ink jet head using shape memory alloy, the ink jet head including a vibrating plate having a shape memory alloy layer and a silicon dioxide layer which are coupled with each other and formed to cover space parts which are formed left and right of a substrate, to be vibrated while the vibrating plate is changed in contour depending upon a temperature variation thereof, an electrode formed on the vibrating plate to have a desired pattern, an ink storing chamber defined between the space parts of the substrate for storing ink, a pressure chamber defined on the vibrating plate for containing ink, the pressure chamber discharging ink by vibration of the vibrating plate, a fluid passage defined by a fluid passage plate which is formed at a side of the pressure chamber, for allowing the ink stored in the ink storing chamber to flow into the pressure chamber, and a nozzle plate attached onto the fluid passage plate and being formed with a plurality of nozzles, for allowing ink to be fired in the form of droplets when the vibrating plate is vibrated, the method comprising the steps of:(a) determining a voltage inputted when a maximum replacement generating time in the shape memory alloy layer is minimal, as a reference input voltage; (b) measuring a first time from a reference input voltage supply starting point to a displacement starting point of the shape memory alloy layer; (c) measuring a second time starting after the first time measured in step (b) to a point when a displacement of the shape memory alloy layer is maximal; (d) determining a sum of the first and second times which are measured in steps (b) and (c), respectively, as a reference input voltage applying time; and (e) determining a driving voltage through repeatedly applying different voltages which are less than the reference input voltage determined in step (a) and measuring firing velocities and sizes of ink droplets which correspond to the respective voltages.