US 7,347,153 B2Granted

Thread supplying device of sewing machine

AssigneeYamato Sewing Machine Seizo Co., Ltd.

InventorsNorio Nakata, Hiromichi Kurata, Takayoshi Masaoka

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Abstract

A thread supplying device includes a rotator feeding a thread downstream of a thread supply path, the rotator winding a periphery thereof the thread several times and locating in the path extending from a thread supply part to a needle and loopers, a stepping motor continuously drivingly rotating in one way the rotator in synchronism with the main shaft of a sewing machine, thread feed setting means setting a unit thread feeding amount necessary for formation of seams per stitch, and control means automatically controlling the rotation of the motor to feed the unit thread feeding amount set by the setting means for each formation of seams per stitch. This device can stably supply a predetermined amount of the unit thread, and achieve stabilization of stitch performance, irrespective of the type of the thread, and whether the feed of a fabric increases or decreases by a rapid change in the rotational speed of the sewing machine.

Claims9

Dependent claims

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.

3 more elements

Dependencies are inferred from the claim text.