| 摘要 |
PURPOSE:To eliminate the divergence of the position of stoppage due to the fluctuation of a rotary speed by controlling the driving and reverse-phase braking in accordance with the 1st and 2nd position detection signals and by adjusting the starting time of reverse-phase braking by means of a timer. CONSTITUTION:A control device 38 formed of a microcomputer is provided in a control circuit driving a sewing machine and the like and signals from a speed instructing voltage generating circuit 31 and an under-needle position detecting sensor 36, etc. are inputted in the device, whereby a motor M is driven. And, the 1st and 2nd position detection signals are taken out from the sensor and the driving current of the motor M is made ineffective on one hand, while the reverse-phase braking is made effective on the other, and further the reverse-phase braking is made ineffective by the timer means in the control device 38. Accordingly, when there is any fluctuation in the rotational speed of the motor M, the fall time of the position detection signal changes, thereby the start of the reverse-phase braking can be adjusted and thus the motor can be stopped constantly at the prescribed rotational position. |
