Needle positioning control mechanism

Claim 1

FOR USE WITH A SEWING MACHINE HAVING A STITCHING MECHANISM WHICH INCLUDES A ROTATABLE SPINDLE SHAFT DRIVINGLY COUPLED TO A RECIPROCABLE NEEDLE BAR SO THAT PARTICULAR POSITIONS OF THE SPINDLE SHAFT ALWAYS CORRESPOND TO PARTICULAR POSITIONS OF THE NEEDLE BAR, THE COMBINATION COMPRISING, MEANS COUPLABLE TO SAID SPINDLE SHAFT FOR SENSING AT LEAST TWO PREDETERMINED POSITIONS THEREOF, FIRST AND SECOND DRIVE MEANS FOR NON-SIMULTANEOUSLY DRIVING SAID SPINDLE SHAFT, SAID FIRST DRIVE MEANS BEING OPERABLE TO PRODUCE CONTINUOUS UNIDIRECTIONAL MOTION OF SAID SPINDLE SHAFT IN RESPONSE TO THE ACTUATION OF FIRST CONTROL MEANS, SAID SECOND DRIVE MEANS INCLUDING A DIRECT CURRENT MOTOR AUTOMATICALLY ACTIVATABLE AND OPERABLE IN RESPONSE TO SAID SENSING MEANS TO CAUSE SAID MOTOR TO DRIVE SAID SPINDLE SHAFT TO A PARTICULAR ONE OF THE SAID AT LEAST TWO SENSABLE PREDETERMINED POSITIONS BY UNIDIRECTIONAL MOTION IN THE SAME SENSE AS IS PRODUCED BY SAID FIRST DRIVE MEANS WHENEVER THE SENSED POSITION OF SAID SPINDLE SHAFT IS DIFFERENT FROM SAID PARTICULAR ONE OF SAID PREDETERMINED POSITIONS, MANUALLY ACTUABLE CONTROL MEANS OPERATIVE WHEN ACTUATED TO CAUSE THE MOTOR TO COUNTER-ROTATE TO DRIVE SAID SPINDLE SHAFT IN THE OPPOSITE SENSE TO THAT PRODUCED BY SAID FIRST DRIVE MEANS TO DRIVE SAID FIRST MEMBER TO ANOTHER ONE OF THE SAID AT LEAST TWO SENSABLE PREDETERMINED POSITIONS UNDER THE CONTROL OF SAID SENSING MEANS, SAID MOTOR IN BOTH CASES BEING THEREAFTER DYNAMICALLY BRAKED TO A STOP SUBSTANTIALLY INSTANTANEOUSLY BY SHORTCIRCUITING THE MOTOR ARMATURE WINDING UNDER THE CONTROL OF SAID SENSING MEANS.