Abstract: An embroidery sewing machine is provided for automatically driving an embroidery frame along X and Y axes. The bed of the machine is provided with a pair of parallel slots extending parallel to the X axis. A pair of carriages extend through said slots and the opposite ends of a single Y-axis guide rod which extends parallel to the Y-axis are secured to said carriages. A traveller is movably guided along the guide rod and one of said carriages is movably guided along a similar X-axis guide rod mounted below the bed. A pair of servo motors each having a drive roller are disposed under the bed and the carriages and traveller are each provided with a plurality of rollers. Wires extend around the rollers and rotation of one of the servo motors drives the carriages upon which the Y-axis guide rod is mounted along the X-axis guide rod. The rotation of the other servo motor causes the traveller to be driven in the Y-axis direction along the Y-axis guide rod.

Abstract: A speed control device for a sewing machine includes at least means for providing a speed reference voltage signal, means for producing a motor speed voltage signal responsive to an actual speed of the driving motor, and means for comparing the speed reference voltage signal with the motor speed voltage signal to provide a speed difference signal. The speed difference signal is utilized to determine triggering angle of a thyristor means for controlling the motor speed and to maintain the predetermined motor speed irrespective of any variation in the driving torque of the motor, the voltage of the power source and the frequency of the A.C. power source.

Abstract: A motor control system for one stitch sewing control of a sewing machine is disclosed. Motor speed is controlled by controlling the trigger phase of motor drive thyristors. Two needle position detectors are employed to detect the arrival of the sewing needle at predetermined halt positions. A pair of motor speed indication signal generator circuits, a pair of memory circuits and a start pulse generator circuit are employed. When the one stitch sewing mode is selected and the foot controller is forced down, the first memory circuit memorizes the start of one stitch sewing and energizes the first motor speed indication signal generator circuit so as to drive the motor of the sewing machine at a predetermined sewing speed.

Abstract: A motor control system for a sewing machine is disclosed in which motor drive thyristors, a trigger phase control circuit for the thyristors, a comparator circuit for generating a trigger phase indication signal to accelerate or decelerate the motor to an indicated speed which corresponds to force downward on a foot controller, needle position detector means, a brake command circuit, and a predetermined constant trigger phase command circuit are employed. The predetermined constant trigger phase command circuit, which is energized by a stop signal from the foot controller, supplies a predetermined trigger phase indication signal to the trigger phase control circuit to lower the motor speed. The brake command circuit generates, at the time when the needle position detector means detects the sewing needle at a predetermined halt position, a brake command signal. The brake command signal is supplied to a brake means, e.g., dynamic brake means, mechanical brake means, etc.

Abstract: A motor control system for sewing a machine is disclosed in which motor drive thyristors, a trigger phase control circuit for the thyristors to control motor speed, and a dynamic brake control circuit means are employed. The dynamic brake control circuit means includes a shunt thyristor connected in parallel with the armature winding of the motor, and a brake command circuit which triggers the shunt thyristor so as to stop the motor by dynamic braking force. The brake command circuit is energized and triggers the shunt thyristor when a stop command signal and a deceleration detection signal are supplied. Thus dynamic braking of the motor of a sewing machine can be accomplished at a predetermined lower speed. To use the motor as a dynamo for dynamic braking stop control of the motor, a trigger phase clamp circuit is employed. To stop the motor at predetermined halt positions, a timer circuit, a predetermined constant trigger phase command signal generator circuit, and needle position detectors are employed.