| 摘要 |
PURPOSE:To reduce the collector loss of a drive transistor while supplying the prescribed current to a drive coil by controlling the operating voltage to the prescribed value at the energizing time of a drive transistor and varying the value of the operating voltage in response to the reference voltage of operation detecting means. CONSTITUTION:Drive coils 4a-4c are disposed at the position crossing a magnetic flux of a field magnet 5 mounted on a rotor. When the coils 4a-4c are energized from a DC power source 10, a rotor is rotatably driven. The operating voltage at the energizing time of the first drive transistors 1a-1c is controlled to the prescribed value by the operations of an operation detector 15, the second selector 13, the second drive transistor group 2a-2c and smoothing units 3a-3c, and the value of the operating voltage is varied in response to the reference voltage of an operation detector 15. |
