| 摘要 |
PURPOSE:To prevent the sudden drop of rotating speed, by discriminating whether a motor is in resonance state or not depending on the phase difference between a drive frequency signal and a direction signal. CONSTITUTION:A controlling circuit of an oscillatory wave motor is constituted by the use of a microcomputer CPU, of which from the output ports PA, PB and PC are outputted the information deciding the drive frequency, normal or reverse rotation signal, and resonance frequency information. In addition, the motor is equipped with a DA conversion circuit DA, a counter COU1, a magnitude comparator MC1, shift resistors SR and FR, etc., while a phase lock loop is formed of a voltage control oscillator VCO1, a division circuit FR1, etc., with which the phase difference between the frequency signal that generated to the motor and the drive frequency is detected. If this phase difference is in resonance state with the motor, it prohibits the change towards the lowering direction of drive frequency. As a result, it can discriminate whether or not the motor is in resonance state regardless of the change of surrounding circumstances and the sudden speed drop in increasing the speed can thereby be prevented. |
