Thread tensioner for a sewing machine

Abstract

Thread tensioner for a sewing machine. In one example embodiment, a thread tensioner for a sewing machine includes a first disk, a second disk, a spring, a mechanism, and a sensor. The second disk is positioned next to the first disk. The spring is configured to apply tension to a thread positioned between the first disk and the second disk by exerting a force against the second disk. The spring defines a first end, a second end, and a length between the first end and the second end. The mechanism is configured to cause the length of the spring to shorten and to allow the length of the spring to lengthen. The sensor is configured to track a current length of the spring by measuring a dimension of at least a portion of the spring.

1 . A thread tensioner for a sewing machine, the thread tensioner comprising:
 a first disk;   a second disk positioned next to the first disk;   a spring configured to apply tension to a thread that is positioned between the first disk and the second disk by exerting a force against the second disk, the spring defining a first end, a second end, and a length between the first end and the second end;   a mechanism configured to cause the length of the spring to shorten and to allow the length of the spring to lengthen; and   a sensor configured to track a current length of the spring by measuring a dimension of at least a portion of the spring.   
     
     
         2 . The thread tensioner as recited in  claim 1 , wherein the mechanism is a knob configured, when rotated in a first direction, to travel along a threaded shaft toward the spring and thereby cause the length of the spring to shorten, the knob further configured, when rotated in a second direction, to travel along the threaded shaft away from the spring and thereby allow the length of the spring to lengthen. 
     
     
         3 . The thread tensioner as recited in  claim 2 , wherein the sensor is a photodiode array sensor. 
     
     
         4 . The thread tensioner as recited in  claim 2 , wherein the sensor is a magnetic sensor. 
     
     
         5 . The thread tensioner as recited in  claim 2 , wherein:
 the spring defines a rod extending from the second end of the spring; and   the sensor is configured to track the current length of the spring by measuring the position of the rod.   
     
     
         6 . The sewing machine as recited in  claim 5 , wherein the sensor is a potentiometer sensor configured to measure the position of an end of the rod as it interacts with a lever actuator. 
     
     
         7 . The thread tensioner as recited in  claim 5 , wherein:
 the threaded shaft is hollow; and   the rod extends through the hollow threaded shaft in order to be tracked by the sensor.   
     
     
         8 . The thread tensioner as recited in  claim 7 , wherein:
 the rod extends into an opening defined in a housing of the sensor; and   the sensor is configured to track the current length of the spring by measuring the position of an end of the rod within the housing of the sensor.   
     
     
         9 . The thread tensioner as recited in  claim 2 , wherein the sensor is configured to track the current length of the spring by directly measuring a current length dimension of coils of the spring. 
     
     
         10 . The thread tensioner as recited in  claim 2 , further comprising:
 a processor in electronic communication with the sensor and configured to determine a current tension that is being applied to the thread given the current length of the spring.   
     
     
         11 . The thread tensioner as recited in  claim 10 , further comprising:
 a display device in electronic communication with the processor and configured to display the current tension.   
     
     
         12 . A sewing machine comprising:
 a spool holder;   a needle bar configured to have a needle attached thereto;   an electric motor configured, while the needle is threaded with a top thread from a spool on the spool holder, to repeatedly drive the threaded needle through a fabric to form a row of stitches in the fabric; and   a thread tensioner comprising:
 a first disk; 
 a second disk positioned next to the first disk; 
 a spring configured, while the top thread is positioned between the first disk and the second disk, to apply tension to the top thread by exerting a force against the second disk, the spring defining a first end, a second end, and a length between the first end and the second end; 
 a mechanism configured to cause the length of the spring to shorten and to allow the length of the spring to lengthen; and 
 a sensor configured to track a current length of the spring by measuring a dimension of at least a portion of the spring; 
   a processor in electronic communication with the sensor and configured to determine a current tension that is being applied to the top thread given the current length of the spring; and   a display device in electronic communication with the processor and configured to display the current tension.   
     
     
         13 . The thread tensioner as recited in  claim 12 , wherein the mechanism is a knob configured, when rotated in a first direction, to travel along a threaded shaft toward the spring and thereby cause the length of the spring to shorten, the knob further configured, when rotated in a second direction, to travel along the threaded shaft away from the spring and thereby allow the length of the spring to lengthen. 
     
     
         14 . The sewing machine as recited in  claim 13 , wherein:
 the spring defines a rod extending from the second end of the spring; and   the sensor is configured to track the current length of the spring by measuring the position of the rod.   
     
     
         15 . The sewing machine as recited in  claim 14 , wherein the rod is integral with the spring. 
     
     
         16 . The sewing machine as recited in  claim 14 , wherein:
 the threaded shaft is hollow; and   the rod extends through the hollow threaded shaft in order to be tracked by the sensor.   
     
     
         17 . The sewing machine as recited in  claim 16 , wherein:
 the rod extends into an opening defined in a housing of the sensor; and   the sensor is configured to track the current length of the spring by measuring the position of an end of the rod within the housing of the sensor.   
     
     
         18 . The sewing machine as recited in  claim 17 , wherein the sensor is a magnetic sensor configured to measure the position of the end of the rod as it interacts with a magnet. 
     
     
         19 . The sewing machine as recited in  claim 17 , wherein the sensor is a potentiometer sensor configured to measure the position of the end of the rod as it interacts with a lever actuator. 
     
     
         20 . The thread tensioner as recited in  claim 13 , wherein the sensor is configured to track the current length of the spring by directly measuring a current length dimension of coils of the spring.