SPEED CONTROL DEVICE OF MOTOR IN SEWING MACHINE

摘要

PURPOSE:To reduce the error in regard to the stop target position, by checking speed variation and by stopping power supply to a motor. CONSTITUTION:The output of a speed setting device K is converted into a speed designation code with a speed designation device L. A discrete value readout device A reads out discrete values in proportion to the designated speed from a ROM N in compliance with the output of the speed designation device L. A comparison device B compares the output of the discrete value readout device A with the discrete value into which the rotating signal from a rotating signal detection device F is converted with a discrete value conversion device E, and the deviated discrete value thus obtained is outputted into a value-of-time arithmetic device C. The value-of-time arithmetic device C controls a motor through a drive device D. A stop position signal generation device J counts the stop signal based on the output of a needle position detection device P. When the stop signal is generated, a counter device I counts the signal from a rotating angle detection signal device Q. A speed monitor G stops power supply to a motor M when the rotating signal detected with a rotating signal detection device F shows a remarkable change.