Shigeru Jomura

Piezoelectric loudspeaker and a method for manufacturing the same

Disclosed is a piezoelectric loudspeaker. According to the present invention, a piezoelectric loudspeaker comprises: a flat compound piezoelectric sheet in which multiple piezoelectric devices are arranged in an organic material; electrodes which are provided on respective surfaces of the compound piezoelectric sheet; an acoustic impedance matching support layer for maintaining the flat compound piezoelectric sheet in a curved shape and for matching an acoustic impedance; and a support frame for supporting the compound piezoelectric sheet at its circumference. Thus, sound reproduction with a desirable frequency properties that have little distortion can be performed.

Fundamental Consideration of Piezoelectric Multilayer Actuators with Interdigital-Electrode-Type Structure

This study deals with a piezoelectric multilayer actuator with an interdigital-electrode-type structure. This type of actuator is usually badly damaged when large displacements are generated, because of internal tensile stresses in the actuator. The effect of the number of ceramic layers in the actuator on the internal stress was investigated with the help of finite element simulation and experimentally fabricated actuators. Consequently, the actuator with less than 40 ceramic layers could generate large displacements without destruction, while the magnitude of displacement for the 40-layer actuator was 3.4 µm for an applied direct current (DC) field of 150 V.