| 摘要 |
An electric sewing machine has an electric motor, clutch and sewing mechanism (3) which comprises a thread carrying sewing needle (5), an apertured base plate (7) through which the needle reciprocates, further thread carrying means, the thread or threads of which cooperate with the needle thread to form stitches, a presser foot (9) for holding a workpiece during formation of a seam of stitches therein against the base plate and feed means for feeding the workpiece between the presser foot and base plate, in which sensing means (15, 17, 19), control means incorporating delay means and thread severing means are provided, the sensing means for sensing a leading and a trailing edge of a workpiece during formation of a sewn seam therein and for supplying a signal to the control means when each of said edges is sensed, whereby the control means when actuated by the sensing means upon sensing by the sensing means of one end of the sewn seam causes the switching to a constant speed of operation of the sewing machine motor and thereafter, following a delay determined by the delay means, actuation of the thread severing means at said one end of the sewn seam. |
