Patent ID: 7802876

Claim:
An actuator unit to be fixed to a surface of a passage unit in which liquid passages including a plurality of pressure chambers are formed, the actuator unit serving to apply pressure to liquid in each pressure chamber, the actuator unit comprising: a piezoelectric layer; a common electrode formed on one surface of the piezoelectric layer so as to be positioned over the plurality of pressure chambers; a plurality of electric field blocking layers formed on an opposite surface of the piezoelectric layer from the one surface so as to be opposed to the common electrode and outside regions of the respective pressure chambers, the electric field blocking layers being arranged on the opposite surface of the piezoelectric layer so as to be distant from each other in the plane of the opposite surface, each electric field blocking layer having one or more holes, each electric field blocking layer being lower in dielectric constant than the piezoelectric layer; a plurality of lands each of which is positioned so as to cooperate with the piezoelectric layer to sandwich an electric field blocking layer; and a plurality of individual electrodes formed on the opposite surface of the piezoelectric layer so as to be opposed to the respective pressure chambers and the common electrode and neighbor the respective electric field blocking layers, each individual electrode being electrically connected to the corresponding land.