Fabric and yarn structures for improving signal integrity in fabric-based electrical circuits

Abstract

Coaxial and twisted pair conductive yarn structures reduce signal crosstalk between adjacent lines in woven electrical networks. A coaxial conductive yarn structure includes an inner conductive yarn having a plurality of conductive strands twisted together. An outer conductive yarn is wrapped around the inner conductive yarn. An insulating layer separates the inner and outer yarns. A twisted pair conductive yarn structure includes first and second conductive yarns, each including a plurality of conductive strands being twisted together. The first and second conductive yarns are twisted together to form a helical structure. In a woven electrical network, at least one conductor of adjacent conductive yarn structures is connected to ground to reduce signal crosstalk. Coaxial and twisted pair yarn structures may also be formed simultaneously with weaving or knitting the threads that make up the structures into a fabric.

1 . A twisted pair conductive yarn structure comprising:
 (a) a first conductive yarn having a plurality of conductive strands being twisted together;   (b) a second conductive yarn having a plurality of conductive strands being twisted together, the second conductive yarn being twisted together with the first conductive yarn to form a helical structure; and   (c) at least one insulating layer surrounding at least one of the conductive yarns for electrically isolating the first and second conductive yarns from each other.   
   
   
       2 . The twisted pair conductive yarn structure of  claim 1  wherein the conductive strands comprise a conductive material selected from a group including metals, alloys, and conductive polymers. 
   
   
       3 . The twisted pair conductive yarn structure of  claim 1  wherein the insulating layer comprises an electrically insulating material selected from a group including polyvinylchloride; rubber; rubber forming polymers, including polyisoprene, polybutadiene, polychloroprene, and polyisobutylene; polyesters; polyolefins; and polyamides. 
   
   
       4 . The twisted pair conductive yarn structure of  claim 1  wherein the insulating layer is substantially uniform in thickness. 
   
   
       5 . A woven electrical network comprising:
 (a) a first twisted pair conductive yarn structure being woven into a fabric in a first direction, the first twisted pair conductive yarn structure including first and second conductive yarns and at least one insulating layer for electrically isolating the first and second conductive yarns from each other, the first and second conductive yarns being twisted together to form a helical structure, the second conductive yarn being connected to ground;   (b) a second twisted pair conductive yarn structure being woven into the fabric in the first direction and being spaced from the first twisted pair yarn structure, the second twisted pair conductive yarn structure including first and second conductive yarns and at least one insulating layer for electrically isolating the first and second conductive yarns from each other, the first and second conductive yarns being twisted together to form a helical structure, the second conductive yarn being connected to ground; and   (c) an AC signal source being connected to the first conductive yarn of the first twisted pair conductive yarn structure for sending an AC signal over the first twisted pair conductive yarn structure, wherein the grounded second conductive yarns of the first and second twisted pair conductive yarn structures block electromagnetic fields emanating from the first conductive yarn of the first twisted pair conductive yarn structure and thereby reduce crosstalk between the first and second twisted pair conductive yarn structures.   
   
   
       6 . The woven electrical network of  claim 5  wherein conductive yarns of the first and second twisted pair conductive yarn structures each include a plurality of conductive strands being twisted together with each other. 
   
   
       7 . The woven electrical network of  claim 6  wherein the conductive strands comprise a conductive material selected from a group including metals, alloys, and conductive polymers. 
   
   
       8 . The woven electrical network of  claim 5  wherein the insulating layers comprise an electrically insulating material selected from a group including polyvinylchloride; rubber; rubber forming polymers, including polyisoprene, polybutadiene, polychloroprene, and polyisobutylene; polyesters; polyolefins; and polyamides. 
   
   
       9 . The woven electrical network of  claim 5  wherein the insulating layers are substantially uniform in thickness. 
   
   
       10 . The woven electrical network of  claim 5  wherein the first and second twisted pair conductive yarn structures are spaced from each other in the fabric by a predetermined distance. 
   
   
       11 . The woven electrical network of  claim 10  wherein the predetermined distances ranges from about one hundredth of an inch to no more than about one inch. 
   
   
       12 . The woven electrical network of  claim 5  comprising a plurality of nonconductive yarns being woven in the fabric with the twisted pair conductive yarn structures. 
   
   
       13 . The woven electrical network of  claim 12  wherein the nonconductive yarns each comprise a material selected from a group including polyamides, including nylon; polyurethane; polyimides; polyesters; acrylics, acetate materials; viscose materials; and natural fibers, including wool, silk, and cotton. 
   
   
       14 . The woven electrical network of  claim 5  wherein the first and second twisted pair conductive yarn structures comprise warp yarns. 
   
   
       15 . The woven electrical network of  claim 5  wherein the first and second twisted pair conductive yarn structures comprise weft yarns. 
   
   
       16 . A method for making a fabric-based signal transmission system, the method comprising:
 (a) weaving a plurality of nonconductive threads together to form a fabric;   (b) twisting first and second insulated conductive threads together; and   (c) while twisting the first and second insulated conductive threads together, leno-weaving the first and second conductive threads into a first region of the fabric.   
   
   
       17 . The method of  claim 16  wherein performing steps (b) and (c) includes weaving the first and second conductive threads into the fabric in a first direction while simultaneously twisting the threads around adjacent nonconductive threads extending in a second direction in the fabric transverse to the first direction 
   
   
       18 . The method of  claim 16  wherein performing step (c) includes using a Jacquard loom equipped with leno headles. 
   
   
       19 . The method of  claim 16  wherein leno-weaving the first and second conductive threads into the fabric includes interlocking the first and second conductive threads with the nonconductive threads such that, in the first region, the first conductive thread is always on a first side of each of the nonconductive threads and the second conductive thread is always on a second side of each of the nonconductive threads, thereby forming a bottom doup leno weave. 
   
   
       20 . The method of  claim 16  wherein leno-weaving the first and second conductive threads into the fabric includes interlocking the first and second conductive threads with the nonconductive threads such that, in the first region, the first conductive thread alternates between first and second sides of adjacent nonconductive threads and the second conductive thread alternates between the second and first sides of the adjacent nonconductive threads. 
   
   
       21 . The method of  claim 16  comprising, in a second region of the fabric, ceasing steps (b) and (c) and weaving the first and second insulated conductive threads into the fabric. 
   
   
       22 . The method of  claim 21  wherein weaving the first and second insulated conductive threads into the fabric includes skipping at least one of the nonconductive threads and thereby creating a float to facilitate interconnection or disconnection with electrical devices. 
   
   
       23 . The method of  claim 16  wherein the first and second conductive threads form a twisted pair structure. 
   
   
       24 . The method of  claim 16  comprising, concurrently with step (c), leno weaving a third conductive thread into the fabric with the first and second conductive threads to form a coaxial structure.