DRIVE CIRCUIT OF ULTRASONIC MOTOR

摘要

PURPOSE:To decrease the number of switching elements and to improve the characteristic of a motor, by connecting electric input terminals of a piezoelectric substance to the secondary terminals of a transformer and by turning ON and OFF the DC power source at the frequency of mechanical vibration. CONSTITUTION:An ultrasonic motor drive circuit is constituted by connecting the secondary terminals of transformers 21 and 22 made up in a ratio of number of turns 1:n each to the electric input terminals of piezoelectric substances 2 and 3 sticking to a stator. One terminals of the primary winding of these transformers 21 and 22 are connected respectively to the contacts of two pairs of switching elements 11 & 12 and 13 & 14 operating in opposite phase. These switching element couples are driven and controlled so that the high-frequency voltage with a phase difference of 90 deg. may be applied to the piezoelectric substances 2 and 3. The voltage by a factor of n on the primary side is thereby induced to the secondary side of transformers 21 and 22, which is applied to the piezoelectric substances 2 and 3 with which the ultrasonic motor is driven.