| 摘要 |
PURPOSE:To reduce noise by current-driving a DC brushless motor with a drive signal having an abrupt edge at the time of rotating the motor at a low speed, and voltage-driving it with a drive signal having a smooth and linear edge at the time of rotating the motor at a high speed. CONSTITUTION:A DC brushless motor driving circuit is composed of a Hall element 1, a current driving motor drive signal generator 2, an amplifier 3, a voltage driving motor drive signal generator 4, an amplitude variable amplifier 5, a switching circuit 6, a motor driving stage 7, a speed detector 8, a frequency generator 10, frequency/voltage converters 11, 14, a control amplifier 13, etc. The circuit 6 is closed at its (a) side by the output of the detector 8 at the time of rotating a motor 9 at a low speed, and the motor 9 is current-driven through the amplifier 3 by a current driving motor drive signal output from the generator 2. The circuit 6 is closed at its (b) side by the output of the detector 8 at the time of rotating the motor 9 at a high speed, and voltage-driven. Thus, the vibration of a coil is substantially eliminated. |
