Patent ID: 7124697

Claim:
A thread tensioning apparatus for adjusting and monitoring the tension in a thread passing through a sewing machine during a stitching operation, comprising: a pair of clamping members movably mounted in juxtaposition with one another, the clamping members being movable towards one another and into clamping relation with the thread passing therebetween during the stitching operation, an electromechanical compression load cell disposed in contacting relation against one of said clamping members, said load cell being separate and apart from said clamping members and operable under compression to generate an output signal representative of the compressive load placed on said load cell and the tension in said thread, a comparator for receiving and comparing the output signal to a predetermined value representative of a desired thread tension and providing a command signal to indicate that the clamping pressure against the thread and thus the tension in the thread is not in conformance with the desired tension, a force member for biasing the other of said clamping members towards said one clamping member and against said thread, said thread being squeezed between said clamping members and said one clamping member being forced against said load cell wherein to place a compressive force on said load cell, a manually operated adjustment knob, said knob being abutted against said force member and mounted for movement towards and away from said load cell for increasing or decreasing the compressive force applied by said force member against said load cell, and wherein when the comparator generates a command signal that the tension in the thread is not in conformance with the desired tension, the adjustment knob is moved towards or away from the load cell to increase or decrease the compressive force of the clamping members on the thread to adjust the tension in the thread as needed.