Patent ID: 7192124

Claim:
A piezoelectric actuator disposed to face a plurality of pressure chambers, the piezoelectric actuator comprising: a plurality of piezoelectric layers and a plurality of electrode layers which are alternately stacked on each other; and a plurality of active portions which are provided in the piezoelectric layers to be aligned with the pressure chambers, respectively, and are defined between at least one pair of electrode layers that are opposed to each other in a direction of stacking of the piezoelectric layers and the electrode layers, the active portions being deformed when an electric voltage is applied to the electrode layers, the electrode layers comprising (a) at least one individual-electrode layer including a plurality of individual electrodes which are aligned with the pressure chambers, respectively, (b) at least one first common-electrode layer including a plurality of first common electrodes which are maintained at a common electric potential and are aligned with the pressure chambers, respectively, and (c) at least one second common-electrode layer including at least one second common electrode which is maintained at the common electric potential and is opposed commonly to the plurality of pressure chambers, wherein said at least one second common-electrode layer is provided by at least one of opposite outermost layers of the electrode layers.