Patent ID: 7654654

Claim:
An ink jet printer head, comprising: a cavity unit including a plurality of ink ejection nozzles, and a plurality of pressure chambers communicating with the ink ejection nozzles, respectively; a piezoelectric actuator including a plurality of active portions each of which is driven to change a pressure of an ink accommodated in a corresponding one of the pressure chambers, and thereby eject, from a corresponding one of the ink ejection nozzles, a droplet of the ink, the piezoelectric actuator including at least one common electrode common to the active portions, and a plurality of individual electrodes corresponding to the active portions, respectively, the cavity unit and the piezoelectric actuator being fixed to each other; and a wiring substrate having at least one common wiring, and a plurality of individual wirings each of which cooperates with said at least one common wiring to apply an electric voltage to a corresponding one of the active portions, wherein the piezoelectric actuator further includes a plurality of pairs of first common electrode connection pads and a plurality of pairs of first individual electrode connection pads which are provided on an outer surface thereof such that the two first common electrode connection pads of each of said pairs are located at respective positions symmetric with each other with respect to a first reference point on the outer surface and the two first individual electrode connection pads of each of said pairs are located at respective positions symmetric with each other with respect to the first reference point, and such that the first common electrode connection pads are electrically connected to said at least one common electrode and the first individual electrode connection pads are electrically connected to the individual electrodes, respectively, and wherein the wiring substrate further includes at least one second common electrode connection pad connected to the common wiring, and a plurality of second individual electrode connection pads which are connected to the individual wirings, respectively, and are provided at respective positions assuring that when the wiring substrate takes a first angular phase about a second reference point corresponding to the first reference point, said at least one second common electrode connection pad is electrically connected to at least one of the first common electrode connection pads and the second individual electrode connection pads are electrically connected to the first individual electrode connection pads, respectively, and when the wiring substrate takes a second angular phase differing from the first angular phase by 180 degrees about the second reference point, said at least one second common electrode connection pad is electrically connected to at least one of the first common electrode connection pads and the second individual electrode connection pads are electrically connected to the first individual electrode connection pads, respectively.