| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor, which can be driven at an optimum driving frequency even in a case that a temperature change and a load change, etc. occur, and reduce its cost and size with a simple structure. <P>SOLUTION: In the ultrasonic motor 1, expanding and contracting oscillation of two stacked piezoelectric elements 13 arranged to face in the side surface of a rod-shaped elastic body 11, is utilized. Vertical oscillation and twisted oscillation are simultaneously excited in the rod-shaped elastic body 11. A rotor is rotated by exciting elliptic motion in a friction device 15 prepared at the end face of the rod-shaped elastic body 11. The stacked piezoelectric element 13 is formed by alternately laminating a first piezoelectric sheet 31 and a second piezoelectric sheet 32. The first piezoelectric sheet 31 is provided with a first internal electrode A+, B+, which are divided into two or more parts, and each divided part is exposed to a peripheral edge of the piezoelectric sheet 31. The second piezoelectric sheet 32 is provided with an internal electrode A-, B-, which has a polarity reverse to the first internal electrode A+, B+, and is divided into two or more parts, and each divided part is exposed to a peripheral edge of the piezoelectric sheet. <P>COPYRIGHT: (C)2010,JPO&INPIT |
