Abstract: A drive device for a sewing machine which varies the speed of the auxiliary motor. In a sewing machine drive device, the rotation of a clutch motor is transmitted through a pulley and an endless belt to the spindle of the sewing machine. The rotation of an auxiliary motor is transmitted through a driving sprocket, a timing belt and a driven sprocket and through the pulley to the spindle of the sewing machine. The drive device includes rotation varying means which varies the rotation of the auxiliary motor in response to the variation in diameter of the driving pulley of the clutch motor.

Abstract: This invention relates to a sewing machine control device which precisely and effectively stops a sewing machine at the termination point of a seam. The sewing machine control device comprises operation means (LSW) for producing an actuation signal or a stop signal, needle position detector means (NP), workpiece detector means (5, WS) operatively connected to said operation means and an electrical circuit operatively connected to said workpiece detector means. When the operation means drives or stops the sewing machine and the workpiece detector means detects the trailing end edge of a workpiece, the electrical circuit automatically stops the sewing machine.