Ceramic actuator with three-dimensional electrode structure

An actuator has been developed by multilayer piezoelectric ceramic green sheets with line electrodes in such a way that electrode lines are parallel and slide one-half a pitch in alternate layers. Large displacements were obtained by the multiplication of the longitudinal converse piezoelectric effect occurring between the nearest pairs of electrode lines. A long cofired multilayer actuator with a large displacement can be easily produced, and reliability is improved by eliminating exposure of the opposite-polarity electrodes on the same surface of the actuator to humidity in the air. For example, a 74-mm-long actuator with 106 electrode lines on each of 100 layers provided a displacement of 50 mu m/350 V, with a generative force of 350 kg/cm/sup 2/. At 85 degrees C/90% RH (relative humidity) and 180-V constant loading, a lifetime of over 1000 h was demonstrated.<
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