| 摘要 |
PURPOSE:To control the rotating frequency of a DC motor to the prescribed value without affecting the influence of the induction of a magnetic field of the motor by setting the sampling period of means for outputting a DC motor rotating frequency control signal to the rectifying magnification of the switching period of an armature. CONSTITUTION:After a rotating frequency detection signal obtained from rotating frequency detector 12 having a ring-shaped magnet 121 and a pattern coil 122 is amplified by an amplifier 13, it is shaped to a rectangular wave by a Schmitt trigger circuit 14, frequency-divided by a frequency divider 15, and then supplied to a frequency/voltage converter 16. The converter 16 samples the output signal of a frequency divider 15 at the sampling period set to the rectifying magnification of the switching period of armatures 111-113, and outputs a control voltage for holding the rotating frequency of the DC motor 11 to the prescribed value in response to the sampling value. |
