| 摘要 |
PURPOSE:To make the pitch of backstitching constant, by supplying an intermittent signal to energize a solenoid for a cloth feed reversing mechanism and applying a continuous signal for a period corresponding to the last stitch. CONSTITUTION:The output of a tachometer generator TG is applied to a speed control circuit SPC to generate a clutch coil signal CLS or a brake coil signal BRS. The output of the tachometer generator is controlled by a foot-pressed switch FSW. The output signal of the lower position detector DD of a position detecting unit PS for sewing-machine needle is applied to a reversal control circuit BTC to produce a signal BTS for energizing a solenoid for a cloth feed reversing mechanism. The signal BTS is made intermittent to reduce power consumption. When the solenoid is deenergized, the signal BTS is made continuous for a period corresponding to a final stitch. According to this constitution, timing can be arranged. As a result, the pitch of backstitching can be made constant. |
