Touch Sensor Fabric

Abstract

A method and apparatus are provided for a touch sensor made from fibers with conductive and non-conductive regions. The fibers are woven into a fabric and connected to control electronics. The fibers are grouped and the ends of the fibers in a group are connected together prior to connection to the control electronics in order to reduce the number of connections required between the sensor fabric and control electronics. The control electronics drive signals to the sensor fabric and measure signals from the sensor fabric to determine touch locations and touch contact areas.

1 . A fiber with conductive and non-conductive regions where the non-conductive regions of two crossing fibers keep the conductive regions apart when at rest, but allow the conductive regions to come into contact upon application of an external compressive force over the overlap region. 
     
     
         2 . The fiber of  claim 1 , where multiple fibers are woven into a fabric. 
     
     
         3 . The fiber of  claim 1 , where the cross section of the fibers is wider in one direction than the other so the orientation of the fiber stays consistent when it is woven into a fabric. 
     
     
         4 . The fiber of  claim 1  where the conductive region is in the middle of the fiber and the non-conductive regions are on the side of the fiber. 
     
     
         5 . The fabric of  claim 2 , where the fibers are grouped, and then fibers within each group are connected together at their ends and then connected to control electronics. 
     
     
         6 . The groups of  claim 5 , where all the groups have the same number of fibers. 
     
     
         7 . The assembly of  claim 5 , wherein identifying the intersecting fiber groups experiencing a touch comprises conducting a parallel search of the fiber groups. 
     
     
         8 . The assembly of  claim 5 , wherein identifying the fibers within a fiber group experiencing a touch comprises:
 apply a voltage gradient along a fiber group in a first orientation;   read the voltage at the terminal of a fiber group in a second orientation;   determine the fiber in contact by calculating where the read voltage falls between the known voltages for the first and last fibers of the fiber group in a second orientation.   
     
     
         8 . The assembly of  claim 5  where the contact area of a touch on two intersecting fiber groups is determined by measuring the resistance of a path from the terminals of the fiber group in a first orientation to the terminals of the fiber group in the second orientation.