Sewing machine drive control

Claim 2

A control system for a sewing machine and the like, having drive means connected to a motive source, comprising: a direct current motor having a low inertial rotor mechanically coupled to the drive means of the machine; switch means controllable by the operator for providing a stop command; drive signal means including: transformer means for developing a variable alternating current signal and manually operable means for controlling the transformer means to vary said alternating current signal and means for converting the alternating current signal into a variable unidirectional current, said drive signal means being disabled by the stop command; needle position sensing means; and motor torquing means responsive to the stop command and the needle position sensing means for developing a limited duration torquing signal for driving the motor until the needle reaches a predetermined position when the drive signal means is disabled.

Claim 3

A control system as set forth in claim 1, wherein: the motor torquing means provides a torquing signal of selectively opposite electrical polarities for direct application to the motor.

Claim 4

In a sewing machine including a drive member and a needle coupled to said drive member and reciprocatable thereby between raised and lowered positions, a direct current motor having a low inertia motor drive coupled to said sewing machine drive motor, a first dc power supply for energizing said motor including a variable ac output transformer and rectifier means for converting said transformer ac output to dc of a value responsive to the value of said ac output, manually operable means for controlling said transformer to vary said ac output between maximum and minimum values, a second dc power supply, means for sensing the displacement of said needle from a predetermined position and means responsive to said manually operable means for effectively disconnecting said first power supply dc output from said motor when said transformer is adjusted to its minimum ac output and connecting said second power supply dc output to said motor, and means responsive to said needle being at said predetermined position for minimizing the output of said second power supply whereby to stop said needle when it reaches said predetermined position.

Claim 5

In a sewing machine including a drive member and a needle coupled to said drive member and reciprocatable thereby between raised and lowered positions, a direct current motor having a low inertia motor drive coupled to said sewing machine drive motor, a first dc power supply for energizing said motor including a variable ac output transformer and rectifier means for converting said transformer ac output to dc of a value responsive to the value of said ac output, manually operable means for controlling said transformer to vary said ac output between maximum and minimum values, a second dc power supply, means for sensing the displacement of said needle from a predetermined position and means responsive to said manually operable means for effectively disconnecting said first power supply dc output from said motor when said transformer is adjusted to its minimum ac output and connecting said second power supply dc output to said motor, and means responsive to said needle being at said predetermined position for minimizing the output of said second power supply whereby to stop said needle when it reaches said predetermined position.

Claim 6

The sewing machine of claim 3 wherein the direction of the dc current output of said second power supply applied to said motor is responsive to said needle position sensing means to drive said motor in a forward or reverse direction to respectively advance or retract said needle to said predetermined position.

Claim 7

The sewing machine of claim 3 including means for shorting said motor as said transformer is adjusted to its minimum output position.