| 摘要 |
PURPOSE:To improve an efficiency, by controlling the poster supply voltage applied to a DC motor through controlling the pulse width modulation circuit of a switching regulator based on the difference in period between a desired rotational period and the rotational period of the motor, and by removing the margin of the power supply voltage when rotating steadily. CONSTITUTION:Provided are a motor driving circuit 12 which drives a DC motor 10, and a switching regulator 16 which feeds the DC voltage obtained through switching by a pulse width modulation circuit 14, to the motor driving circuit 12 as a power supply voltage. Further, a control signal for the pulse width modulation circuit 14 is generated based on a difference in period T between a desired rotational period T1 and a rotational period T2 of the motor 10. Then, provided is a control means 18 which reconciles the rotational period of the motor with the desired rotational period by adjusting the power supply voltage for the motor driving circuit 12 through the generated control signal. Here, the control means 18 so operates as to decrease the power supply voltage by generating the control signal, which makes a pulse width narrow, when the difference in period T is positive and as to increase the power supply voltage by generating the control signal, which makes the pulse width wide, when the difference in period T is negative. |
