| 摘要 |
PURPOSE:To reduce the influence an oscillatory wave motor on the drive control even when the voltage of a power source battery in a camera main body fluctuates so as to accurately control the position of a lens when the oscillatory motor is used as a lens drive motor. CONSTITUTION:A low-pass filter composed of a resistor 21 and capacitors 22 and 23 is provided to the drive system of an oscillatory wave motor 9 and electric power is supplied to an oscillatory wave motor drive circuit from a battery 29 through the low-pass filter. Therefore, the voltages of amplifiers 5 and 6 which supply electric power to the phases A and B of the motor 9 do not drop abruptly, but vary gently even when the voltage of the battery 29 instantaneously drops, because supplemental power supply is made from the capacitor 23. In the case the speed of the motor 9 is decelerated from a desired speed by a prescribed speed, the motor 9 is maintained at a constant speed by controlling the drive frequency. |
