Piezoelectric and/or electrostrictive actuator having dummy cavities within ceramic substrate in addition to pressure chambers, and displacement adjusting layers formed aligned with the dummy cavities

A piezoelectric and/or electrostrictive actuator comprising (a) a ceramic substrate in which pressure chambers are formed in a row extending in a longitudinal direction of said substrate, said ceramic substrate including a spacer plate having a plurality of windows which provide said pressure chambers, said plurality of windows being formed in a row extending in a longitudinal direction of said spacer plate, a closure plate superposed on one of opposite major surfaces of said spacer plate so as to close one of opposite openings of each of said windows, and a connecting plate superposed on the other major surface of said spacer plate so as to close the other opening of each of said windows, said spacer plate, said closure plate and said connecting plate being formed from respective ceramic green sheets which are laminated on each other and fired into an integral structure as said ceramic substrate, and (b) piezoelectric and/or electrostrictive elements which are disposed on respective portions of an outer surface of said closure plate which partially define said pressure chambers, respectively, said elements being energized to cause deformation of said respective portions, so as to change pressure levels of the corresponding pressure chambers, each of said piezoelectric and/or electrostrictive elements comprising a lower electrode, a piezoelectric and/or electrostrictive layer and an upper electrode which are formed in the order of description by a film-forming method on the outer surface of said closure plate in alignment with the respective pressure chambers, wherein the improvement comprises:

• said spacer plate having auxiliary windows having a predetermined size formed adjacent to respective two outermost windows which are located at opposite ends of the row of said plurality of windows of said spacer plate, said auxiliary windows providing dummy cavities within said ceramic substrate such that said dummy cavities are formed adjacent to respective two outermost pressure chambers which are located at opposite ends of said row of said pressure chambers;
• and
• displacement adjusting layers having a suitable pattern which are integrally formed on respective portions of the outer surface of said closure plate which are aligned with said auxiliary windows of said spacer plate.