| 摘要 |
PCT No. PCT/JP88/00880 Sec. 371 Date Jun. 22, 1989 Sec. 102(e) Date Jun. 22, 1989 PCT Filed Sep. 2, 1988 PCT Pub. No. WO89/02186 PCT Pub. Date Mar. 9, 1989.The present invention relates to a drive device for a brushless motor utilizing no position detector for detecting the position of a movable element of the motor. The drive device comprises a phase controlled loop for controlling an output of a voltage controlled oscillator (40) by supplying an electric power to motor driving coils (1, 2, 3), detecting the difference in phase between the power supply waveforms thereof and a counterrelectromotive force of the motor driving coils during a power supply interrupting period with the use of a phase difference detector (20) and inputting a detected phase difference signal to the voltage controlled oscillator (40), an oscillation frequency initializing means (70) and a driving transistor interrupting circuit (80).
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