| 摘要 |
PURPOSE:To enable to stably control the speed of a motor by supplying a short pulse having sufficient voltage level for breaking down an insulating film formed between a brush and a rotor to a motor together with a motor control signal. CONSTITUTION:A motor 19 with a brush is connected in bridge together with resistors R1-R3, a voltage between C and D is set to become proportional to the voltage of a motor control signal, thereby controlling the rotating speed of the motor 19. At this time, a signal of a motor control signal generator 16 and a signal of a pulse generator 17 for generating a signal having a voltage level sufficient to break down the insulating film formed between the brush and the rotor of the motor 19 and a pulse width of the degree not affecting the influence to the rotation of the motor 19 are added by a drive circuit 18 and applied to the motor 19. Accordingly, the contacting state of the brush can be improved so that the motor can be stably controlled at the speed even in the low voltage range. |
