JP2574675B

PURPOSE:To increase driving force and availability, by elongating/shrinking an annular vibration chip and a piezoelectric laminate in circumferential direction while complementing each other. CONSTITUTION:An annular vibration chip 1 is formed from a ceramic electrostriction element and polarized vertically such that the underface has positive polarity while the upper face has negative polarity, then an earth side electrode 2 is arranged on the underface and split electrodes 3 are arranged respectively in sections of the upper face split into four. Furthermore, a piezoelectric laminate 5 is secured through an insulation layer 6 to partial face on the earth side electrode 2 corresponding to the split position of the split electrode 3 with the laminating direction thereof being aligned with the tangential direction of the annular vibration chip 1. Alternating voltage having phase shifted by 2pi/n in circumferential direction is applied onto the split electrode 3, and similar alternating voltage is also applied onto the piezoelectric laminate 5. Consequently, elongating/shrinking motion in circumferential direction of the annular vibration chip 1 and elongating/shrinking motion of the piezoelectric laminate 5 are complemented each other, thus producing a large driving force.