Importance

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Abstract

In a sewing machine with a microcomputer controlled step motor for the control of the magnitude and direction of the feeding action of a cloth feeder, the microcomputer is connected, via a buffer and a D/A converter, to the non-inverting input of a comparator which controls the turn-on and turn-off as well as the current intensity of each phase winding of the step motor and whose inverting input is connected to a discriminating element disposed in the phase circuit, for the step setting correction and for the torque intensification of the step motor. To adapt the correction possibilities to the step motor parameters, the D/A converter has four input stages whose biggest stage is connected to the corresponding output stage of the buffer via a voltage divider.

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First Claim