| 摘要 |
PURPOSE:To reduce acoustic noises while improving the efficiency of a motor by mounting a gain-control amplifier circuit amplifying an output signal from a magnetic sensitive element for sensing a position and controlling the gains of the gain-control amplifier circuit by driving supply voltage. CONSTITUTION:The inclined waveforms of output signals from magnetic sensitive elements 1a-1c for sensing a position are extracted, driving voltage (a)-(c) having the same edge sections as the inclined waveforms are formed, and the driving voltage (a)-(c) are fed to stator coils 3a-3c. Gain-control amplifier circuits 10a-10c amplifying output signals from the magnetic sensitive elements 1a-1c are fitted, and the gains of the gain-control amplifier circuits 10a-10c are controlled by driving supply voltage. |
