Piezoelectric lamination actuator

Abstract

A piezoelectric lamination actuator is disclosed which is used as a driving source, such as for a printer head. In the actuator, a number of piezoelectric layers, each sandwiched between internal electrodes, are laminated with one on top of another by glue. A dielectric layer is glued on each end of the laminated piezoelectric body formed of piezoelectric layers, and thin-film external electrodes are formed on two diagonally opposite sides of the laminated piezoelectric body. One thin-film external electrode is connected to every second internal electrode, and the other thin-film external electrode is connected to the remaining internal electrodes. External electrodes are formed by sputtering or by thin metal straps, to reinforce the external electrodes and associated soldering joints. Dielectric layers at both ends of the actuator can be made up of a plurality of dielectric sub-layers glued together by a moisture resistant adhesive agent, thereby preventing moisture from entering through the dielectric layers. A multiple-unit actuator can be formed of a plurality of actuator units attached with one another at their dielectric layers. Metal straps are employed to connect the neighboring external electrodes of the actuator units. Projected portions are eliminated, and the actuator is made compact. Dielectric layers at the ends of the actuator are thicker than the rest of the intermediate dielectric layers, thereby allowing a larger coating area on the end dielectric to effectively prevent moisture from entering. The thinner intermediate dielectric layers minimize reductions in the displacement output.