Toko Inc. exhibited a piezoelectric element under development that is designed to drive an ultrasonic motor at CEATEC Japan 2007, which runs from Oct. 2 to 6, 2007.
In the existing piezoelectric element, two pairs of electrodes for voltage supply are required. According to Toko, however, the new element only needs one pair of electrodes to perform operations nearly equivalent to those of the existing product. This makes the structure of the new element simpler, which, in turn, leads to a reduction in the production cost. The details, however, have not been announced.
The new piezoelectric element has a structure in which a PZT piezoelectric element is sandwiched between two electrodes. When the two electrodes are applied with an AC voltage, the element will extend and contract in the longitudinal direction of the electrode surface.
By restricting the directions in which the element extends/contracts, two kinds of longitudinal-bending coupling-vibration modes are achieved where the element moves in an undulating fashion. The latest piezoelectric element employs an alumina ceramic chip to restrict the directions.
At the exhibition site, the company performed a demonstration to show how a four-wheel vehicle equipped with this piezoelectric element runs on a battery.