Displacement Characteristics of Series-Type Bimorph Actuator under High Applied Voltage

Experimental and theoretical studies on the applied voltage-displacement characteristics of a piezoelectric series type bimorph were performed. The displacement increased with an increase in the applied voltage until dielectric breakdown. An electric field higher than its coercive field (E c) can be applied to the bimorph, because its poling direction is opposite to the field, owing to an electric charge balance between its two layers. On the other hand, the displacement of a parallel-type bimorph fell to zero when the applied voltage per unit length equalled E c. The series-type bimorph displayed larger displacement and higher reliability than the parallel-type bimorph.