Blind stitch sewing machine

摘要

The invention concerns a blind stitch sewing machine with an oscillating fabric deflector to make the sewing material bulge into the arcuate path of the arc needle. The minimum spacing of the deflector relative to the arc needle can be adjusted in relation to the thickness of the sewing material detected by a sewing material sensor. A stepping motor is provided to adjust this minimum spacing. A stepping motor control circuit is connected to the sewing material sensor, and to a contact pickup for the arc needle and fabric deflector, the stepping motor being controlled in such a manner that, upon a control circuit start signal, it moves into a particular start position and proceeds during the ensuing sewing by one step per stitch reducing the minimum spacing of the fabric deflector until the contact pickup emits a contact signal relative to the arc needle and the fabric deflector during a measurement window signal. At the end of this signal, the stepping motor moves in the opposite direction by a number of steps dependent on the output signal of the sewing material sensor, to increase the minimum spacing of the fabric deflector.