| 摘要 |
PURPOSE:To improve the starting characteristics of an ultrasonic motor by varying the frequency of an AC voltage to be applied from the start of a driver to the arrival at a normal state. CONSTITUTION:An ultrasonic motor drive circuit has a start controller 1 for generating a start signal, a variable oscillator 2, and a frequency controller 3. The output of the oscillator 2 is input at one side through a 90 deg. phase shifter 4 and at the other directly to power amplifiers 5-6, and the outputs are applied to the piezoelectric ceramics 7 of an ultrasonic motor. In this case, a drive signal S1 is so controlled as to vary the frequency of an AC voltage to be applied for each time from the start to the arrival at a normal state at the time of starting. Thus, since the time of the vibration of the driver to arrive at a normal state becomes shorter, its start becomes earlier. |
