Fabric and yarn structures for improving signal integrity in fabric-based electrical circuits
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 woven electrical network comprising:
(a) a first coaxial conductive yarn structure being woven into a fabric in a first direction, the first coaxial conductive yarn structure including an inner conductive yarn, an outer conductive yarn being wound around the inner conductive yarn in a second direction transverse to the first direction and substantially covering the inner conductive yarn, and at least one insulating layer for electrically isolating the inner and outer conductive yarns from each other, wherein the outer conductive yarn is connected to ground;
(b) a second coaxial conductive yarn structure being woven into the fabric in the first direction and being spaced from the first coaxial conductive yarn structure, the second coaxial conductive yarn structure including an inner conductive yarn, an outer conductive yarn being wound around the inner conductive yarn in a second direction transverse to the first direction and substantially covering the inner conductive yarn, and an insulating layer for electrically isolating the inner and outer conductive yarns from each other, wherein the outer conductive yarn is connected to ground; and
(c) an AC signal source being connected to the inner conductive yarn of the first coaxial conductive yarn structure for sending an AC signal over the first coaxial conductive yarn structure, wherein the grounded outer conductive yarns of the first and second coaxial conductive yarn structures block electromagnetic fields emanating from the inner conductive yarn of the first coaxial conductive yarn structure and thereby reduce crosstalk between the first and second coaxial conductive yarn structures.
2. The woven electrical network of claim 1 wherein the inner conductive yarns of the first and second coaxial conductive yarn structures each include a plurality of conductive strands being twisted together with each other.
3. The woven electrical network of claim 1 wherein the outer conductive yarns of the first and second coaxial conductive yarn structures each include a plurality of strands being twisted together with each other.
4. The woven electrical network of claim 3 wherein the strands of the outer and inner conductive yarns each comprise a conductive material selected from a group including metals, alloys, and conductive polymers.
5. The woven electrical network of claim 1 wherein the insulating layers of the first and second coaxial yarn structures 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.
6. The woven electrical network of claim 1 wherein the insulating layers of the first and second coaxial conductive yarn structures are substantially uniform in thickness.
7. The woven electrical network of claim 1 wherein the first and second coaxial conductive yarn structures are spaced from each other in the fabric by a predetermined distance.
8. The woven electrical network of claim 7 wherein the predetermined distance ranges from about one hundredth of an inch to no more than about one inch.
9. The woven electrical network of claim 1 comprising a plurality of nonconductive yarns being woven in the fabric with the first and second coaxial conductive yarn structures.
10. The woven electrical network of claim 9 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.
11. The woven electrical network of claim 1 wherein the first and second coaxial conductive yarn structures comprise warp yarns.
12. The woven electrical network of claim 1 wherein the first and second coaxial conductive yarn structures comprise weft yarns.
13. The woven electrical network of claim 1 wherein the inner and outer conductive yarns of the first and second coaxial conductive yarn structures each exhibit at least one of sufficient flexibility, conformability, resiliency, bending characteristics, and recovery for incorporation in a wearable garment.
14. The woven electrical network of claim 1 wherein the inner and outer conductive yarns of the first and second coaxial conductive yarn structures each comprise a plurality of strands being twisted together and having a diameter of less than twenty microns.
15. The woven electrical network of claim 1 wherein the inner and outer conductive yarns of the first and second coaxial conductive yarn structures each comprise a monofilament yarn having a diameter less than twenty microns.