Buttonhole sewing machine cutter control takes the path between the start of the seam and the start of the cut, to be corrected for fabric movement speed and cutter switching delay times

摘要

To control the action of a cutter at a sewing machine, to cut the slit in the fabric for a buttonhole, a path (wl) between the start of the seam and the start of the cut is passed to the sewing machine speed control unit. The input path length is converted into a corrected path (wl,wh) according to the speed of fabric advance movement through the sewing machine and characteristic delay time (dt) in switching on the cutter mechanism, so that the cutter is activated to start the cut independently of the sewing machine speed.