| 摘要 |
PURPOSE:To reverse-rotate a motor positively by providing a control means detecting whether or not the driving currents of a driving output circuit reach a fixed value or more and weakening the controlling force of a DC servo control loop when a fixed value or more are detected. CONSTITUTION:When the order of the changeover timing of switches S1-S3 in a commutation control circuit 5 is changed over to order reverse to conventional devices in order to reversely rotate a motor, the flowing of excess driving currents sufficiently larger driving currents at the time of normal revolution through driving coils L1-L3 is detected by a driving-current detector 11. Consequently, reference voltage Vref formed by a reference voltage generating circuit 12 is controlled so as to be made smaller than that at the time of normal revolution. Accordingly, the output level of a comparison circuit 4 is lowered, the driving currents of the driving coils L1-L3 are diminished, the revolving torque of the motor M is reduced, the number of revolution of the motor is decreased rapidly, and the order of changeover timing is changed over completely, thus starting the reverse rotation of the motor M, then positively reversing the rotation of the motor M. |
