Automatic sewing machine control device

A sewing speed control method for controlling the sewing speed of a sewing machine, comprising the steps of:

• detecting the operating speed of said sewing machine to produce a current sewing speed level signal;
• comparing the current sewing speed level signal with the next rotation speed level to which the current rotation speed is changed in response to a speed level instruction signal;
• producing a speed level control signal corresponding to a specific operating speed level according to the comparison result;
• and
• controlling the rotation speed of said sewing machine in response to the speed level control signal,
• the speed level control signal being determined as either a zero speed level or a positive speed level not higher than a level represented by the speed level instruction signal.

A control device for controlling a sewing machine to carry out an automatic sewing operation according to a sewing pattern, data which comprise a sewing machine body, an electric motor for driving a spindle of said sewing machine body, means for detecting a speed of the rotation of the spindle of said sewing machine, a cloth presser unit for holding a cloth, a cloth presser drive section for moving said cloth presser unit to a predetermined position, and a control unit for controlling the operations of said motor, cloth presser unit and cloth presser drive section, said control unit comprising:

• a microcomputer carrying out the control operations;
• memory means for storing operation programs for said microcomputer and the sewing pattern data;
• and
• sewing pattern data changing means for changing the sewing pattern data into another sewing pattern data;
• wherein said control unit comprises a PMD for operating said cloth presser unit drive means, count borrow means for transmitting a determination as to whether or not said PMD provide an output, count borrow writing means for writing predetermined data in said count borrow means, needle position detecting means for detecting the needle lower position of said sewing machine and drive timing changing means including PG signal generating means for outputting a PG signal at predetermined time intervals when said sewing machine is rotated, said changing means changing the drive timing of said cloth presser drive section according to a sewing machine speed instruction value.