Electronic Stitch Length Regulator for Home Sewing Machines

Abstract

This invention comprises a means to control stitch length of household sewing machines when used on free-motion quilting frames. A sensor in the form of a computer mouse or a pair of sensors in the form of optical encoders is used to determine the translational speed of the set of carriages that hold the sewing machine. This information is sent to electronic circuitry that converts this information to an electrical resistance which is applied to the foot pedal control electrical connector on the sewing machine. When thusly applied, this resistance sets the rotational speed of the sewing machine. This invention achieves stitch length uniformity by maintaining the proper relationship between the input signal from the sensor or sensors caused by carriage translation and the output resistance to the sewing machine which controls its rotational speed.

1 . An electronic stitch length regulator comprising: a position sensor; a sensor arm; a base plate; an electronic circuit; an electrical output connector.  
     
     
         2 . The electronic stitch length regulator of  claim 1 , wherein the sensor arm is pivotally mounted in the base plate.  
     
     
         3 . The electronic stitch length regulator of  claim 2 , wherein the sensor arm is preloaded longitudinally with a spring element.  
     
     
         4 . The electronic stitch length regulator of  claim 1 , wherein the base plate is mounted below the sewing machine.  
     
     
         5 . The electronic stitch length regulator of  claim 1 , wherein the electronic circuit converts speed of position sensor to electrical resistance measured in Ohms.  
     
     
         6 . The electronic stitch length regulator of  claim 5 , wherein the frequency output of the sensor comprises two channels.  
     
     
         7 . The electronic stitch length regulator of  claim 6 , wherein each channel of frequency signal is converted to a voltage respectively.  
     
     
         8 . The electronic stitch length regulator of  claim 7 , wherein the two channels of voltage are added to form a composite total voltage.  
     
     
         9 . The electronic stitch length regulator of  claim 8 , wherein the composite total voltage is used as an input signal to a comparator circuit.  
     
     
         10 . The electronic stitch length regulator of  claim 9 , wherein the comparator output is dependent on the composite total voltage.  
     
     
         11 . The electronic stitch length regulator of  claim 10 , wherein the comparator output controls an opto-isolator integrated circuit.  
     
     
         12 . The electronic stitch length regulator of  claim 11 , wherein the output of the optoisolator circuit is connected to a plurality of fixed electrical resistors.  
     
     
         13 . The electronic stitch length regulator of  claim 12 , wherein the plurality of fixed electrical resistors are connected to an electrical output connector.  
     
     
         14 . The electronic stitch length regulator of  claim 13 , wherein the electrical output connector plugs into the sewing machine foot pedal connector port.