Abstract
The double-mode miniature cantilever-type ultrasonic motor was fabricated using the array-type multilayer piezoelectric ceramics (array-type MLPC) of (Sr, Ca)_2NaNb_5O_<15> (SCNN) such as Pb-free piezoelectric materials, and the electrical driving properties were investigated. The array-type MLPC was arranged in a 2x2 matrix on the actuators. The ultrasonic motor of SCNN array-type MLPC started to rotate at 1.7V_<p-p,>, and showed such characteristics as revolution speed of Ω_0=1000 rpm, a torque of T_0=2.6μNm at 9V_<p-p>. On the other hand, the motor using Pb (Zr, Ti)O_3-Pnb(Zn, Nb)O_3(PZT) showed Ω_0=1000 rpm, a torque of T_0=2.6μNm at 1V_<p-p>. SCNN motor was not so different from PZT motor, however the SCNN motor needed 10 times as high voltage as the PZT motor. By using the array-type MLPC, the driving voltage was reduced by a half, and the driving properties were improved.
