Patent ID: 7780272
Filing Date: 2010-08-24
Classification: B41J

Abstract:
1. 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 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 piezoelectric film of the piezoelectric actuator extends along the portion of the wall; the first electrode is attached on one surface of the piezoelectric film within a first region overlapping with the portion of the wall; the second electrode is attached on the other surface of the piezoelectric film extending over the first region overlapping with the first electrode; the third electrode is attached on the one surface of the piezoelectric film, adjacent to the first electrode without contacting the first electrode, at a second region overlapping with a portion of the second electrode, the second region of the piezoelectric film being polarized in a same direction as a polarization direction of the first region of the piezoelectric film; 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 a peripheral signal between the second electrode and the third electrode; and the controller applies the predetermined voltage with a same polarity as the ink discharge signal between the second electrode and the third electrode as the peripheral signal.