| 摘要 |
PURPOSE:To prevent the rapid voltage application or stop being a possible cause for strange sounds, by providing an oscillator, the first amplifier to amplify into high-frequency voltage, a phase-shifter to alter phases, and the second amplifier to amplify into high-frequency voltage, and besides by providing gain controllers to change the magnitude of high-frequency voltages slowly. CONSTITUTION:A driving circuit is composed of an oscillator 1 to output a driving signal being a pulse signal, two gain controllers 2 to control gains for voltages applied to an ultrasonic motor 5 receiving a signal from the oscillator 1, two amplifiers to obtain high-frequency voltages amplified properly by the output signal from the gain controllers 2 and the power supply voltage, and a phase shifter 4 provided between the oscillator 1 and one gain controller 2 to obtain high-frequency voltage having different phase. Incidentally, concerning the wave forms of the major sections of this driving circuit, when a driving switch 21 is switched over rapidly, voltages outputted form the gain controllers 2 are pulse-width-modulated, and applied voltages outputted from the amplifiers 3 are switched over slowly. |
