| 摘要 |
PURPOSE:To obtain a large drive torque by driving an ultrasonic motor with a pulsating voltage signal of a duty factor that is not 50%. CONSTITUTION:With respect to an ultrasonic motor M that rotates a rotor by vibration of piezoelectric ceramic, a drive device is made up of a CPU 1, an oscillator 2, an inverter 3, a binary counter 4, data selectors 5, 8 and 9, shift registers 6 and 7, AND circuits 10 and 11, and a driver 12. A phase of pulse signals that have a predetermined frequency and are applied to two electrodes formed on the piezoelectric ceramic is shifted 90 degrees, and also the duty ratio of these pulse signals is set to a value other than 50%. The largest amplitude value of the piezoelectric element becomes a drive frequency. Consequently, a drive torque of the ultrasonic motor M is increased, and a drive efficiency is improved. |
