Patent ID: 7712877

Claim:
An inkjet printer comprising: a pressure chamber communicating with a nozzle, the pressure chamber capable of being filled with ink; a piezoelectric actuator having a first piezoelectric film, a second piezoelectric film, a first electrode, a second electrode, and a third electrode; and, a controller to apply voltage between the first electrode and the second electrode and between the third electrode and the second electrode independently; wherein: the piezoelectric actuator forms a portion of a wall defining the pressure chamber; the first electrode, the first piezoelectric film, the second electrode, the second piezoelectric film, and the third electrode are laminated together in this order; the first electrode is positioned within a region overlapping with the portion of the wall along a direction of lamination of the piezoelectric films and electrodes; the second electrode and the third electrode are positioned so as to overlap with the first electrode along the direction of lamination; the piezoelectric actuator deforms so as to project toward the pressure chamber and to decrease a volume of the pressure chamber while the controller applies voltage between the first electrode and the second electrode; the controller applies an ink discharge signal between the first electrode and the second electrode, the ink discharge signal comprising an advanced voltage change from a predetermined voltage to a lower voltage and a subsequent voltage change from the lower voltage to the predetermined voltage wherein the combination of the volume increase and the subsequent volume decrease of the pressure chamber due to the ink discharge signal causes ink to discharge from the nozzle; the controller further applies an additional signal between the second electrode and the third electrode; the controller applies the ink discharge signal without applying the additional signal; and the controller applies the additional signal without applying the ink discharge signal.