Sewing machine having spindle drive motor and rotary hook drive motor

A sewing machine for stitching a workpiece fabric by a needle formed with an eyelet comprising:

• a sewing machine motor;
• a spindle driven by the sewing machine motor for driving the needle;
• a bed having a throat plate;
• a rotary hook provided in the bed for trapping a needle thread loop in cooperation with the needle;
• a rotary hook drive motor provided independent of the sewing machine motor and rotatable in synchronization with the spindle at a synchronous rotation speed;
• and
• control means for controlling the rotary hook drive motor so that an engaging period of the needle thread with the rotary hook is prolonged for a predetermined time, whereby the residual leading end part of the needle thread provided appearing at a top side of the workpiece fabric is drawn into a bottom side thereof at a stitch starting time.

A sewing machine for stitching a workpiece fabric by a needle formed with an eyelet comprising:

• a sewing machine motor;
• a spindle driven by the sewing machine motor for driving the needle;
• a bed having a throat plate;
• a rotary hook provided in the bed for trapping a needle thread loop in cooperation with the needle;
• a rotary hook drive motor provided independent of the sewing machine motor and rotatable in synchronization with the spindle at a synchronous rotation speed;
• a thread cutting mechanism disposed in the bed for cutting the thread at a position below the throat plate;
• a first control section controlling the sewing machine motor, needle location data containing N number of stitch being stored in the first control section, the threat cutting mechanism performing thread cutting operation at a final Nth number of stitch, and
• a second control section connected to the first control section and controlling the rotary hook drive motor and the thread cutting mechanism, the second control section controlling rotation of the rotary hook drive motor in accordance with a predetermined rotation angle of the spindle so that an engaging period of the needle thread with the rotary hook is prolonged for a predetermined time, whereby a residual leading end part of the needle thread passing through the eyelet has a length capable of avoiding release of the residual leading end part from the eyelet of the needle during cutting of the thread by the thread cutting mechanism at the final Nth number of stitch.