Automatic embroidery sewing machine

摘要

A sewing machine is provided which automatically drives an embroidery frame in two directions of X- and Y-axes during the time a sewing needle is disengaged from a cloth to be worked. An X-axis drive system and a Y-axis drive system are provided which drive the embroidery frame in the directions of the X- and Y-axes in a conventional manner. The machine includes an electromagnetic clutch mechanism which selectively engages or disengages a needle bar with or from a needle bar drive system in order to permit an increased stroke selectively for which the embroidery frame is driven for each stitch. Additionally, an electronic control system is provided which energizes the electromagnetic clutch mechanism to disengage the needle bar from the needle bar drive system whenever either one of X-axis and Y-axis components of the stroke contained in an embroidery sewing data exceeds a given value, and which deenergizes the clutch mechanism after the termination of driving the embroidery frame and engages the needle bar with the needle bar drive system. If either component of the stroke exceeds the given value, the arm shaft idles to maintain the needle bar at its upper dead center during the time the embroidery frame is being driven. Subsequently, when the drive to the embroidery frame is terminated, a downward movement of the needle bar is allowed.