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US 5,189,968 AGranted
Digital controller with A.C. induction drive for sewing machines
AssigneeBrown Group, Inc.
InventorTerry I. Eichenseer
Life of this patent
Estimating the term…
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AssigneeBrown Group, Inc.
InventorTerry I. Eichenseer
Estimating the term…
Apparatus for use with an A.C. induction motor drive for a sewing machine to supplant a clutch-brake mechanism by supplying an A.C. induction motor drive to supply power to the motor to control its operating speed and needle position. The control embodies a programmable controller responsive to information loaded into it to derive a profile of how the sewing machine is to operate to sew workpieces, and to generate a control signal which is supplied to the motor drive to operate the motor in accordance with the profile in association with a speed command encoder responsive to a manipulative operator control to produce speed signals to speed up or slow down. The encoder senses the position of the motor and provides a position signal representative of the needle and signals the controller in a closed-loop control system.
In a motor driven sewing machine having an A.C. induction motor, the improvement comprising:
In a motor driven sewing machine the improvement of a programmable closed-loop feed back controller having means to effect changes in sewing speed commands by a velocity observer comprising a sewing machine shaft and a shaft position encoder for determining sewing needle position, a velocity observer, a shaft speed encoder operatively connected to said sewing machine shaft for continuously monitoring said sewing machine shaft positions, an AC drive motor responsive to said speed encoder and programmable closed-loop feedback controller to maintain a linear rate of speed change whereby a deceleration rate of said AC drive motor is dynamically lowered to increase needle position accuracy.
Dependencies are inferred from the claim text.