Patent ID: 7347153
Filing Date: 2008-03-25
Classification: D05B

Abstract:
1. A thread supplying device for a sewing machine, the sewing machine having a main shaft, disposed at any point in a thread supply path extending from a thread supply part to a movable sewing member including a needle, the thread supplying device comprising: a rotator having a thread winding around a periphery of said rotator at least one time, wherein the rotator feeds the thread downstream of the thread supply path; a motor continuously drivingly rotating said rotator in one direction and in synchronism with said main shaft of the sewing machine; a thread feed setting apparatus for setting a unit thread feeding amount necessary for forming seams per stitch; a thread tension detecting apparatus located downstream of the rotator in the thread supply path; and a control apparatus for automatically controlling an amount of rotation of the motor for feeding a thread of the unit thread feeding amount set by the setting apparatus for each formation of seams per stitch, wherein said control apparatus changes the amount of rotation of the motor depending on a magnitude of a thread tension immediately after being fed from the rotator and detected by the thread tension detecting apparatus.