Patent ID: 8448588
Filing Date: 2013-05-28
Classification: D05B

Abstract:
1. A force sensing device adapted for sensing thread tension in a long-arm or mid-arm sewing machine, the force sensing device comprising, the sewing machine mechanically coupled to a tension adjuster threaded post; the tension adjuster threaded post is immediately adjacent to a force sensor disk, a tension spring washer, a tension spring and a tension adjusting knob in this manner a user can rotate the tension adjusting knob to compress the tension spring against the tension spring washer which compresses the force sensor disk against the sewing machine to increase or decrease thread tension as necessary; the force sensor disk comprises a variable resister that is electrically coupled to a force sensor disk cable; the force sensor disk cable is electrically coupled to a measurement resistor RM, a load resistor RL, a battery and a power switch configured to form a force sensing resistor; and in this manner as the tension on the force sensor disk increases, a force sensor disk resistance decreases and voltage across the measurement resistor RM increases; a digital readout meter measures the voltage across measurement resister RM, which directly relates to the tension on the force sensor disk; a tension related voltage is displayed on a display screen and can be viewed by the user who can increase or decrease the tension as necessary.