Detector contructed from fabric

• US 6,452,479 B1
• Filed: 01/22/2001
• Issued: 09/17/2002
• Est. Priority Date: 05/20/1999
• Status: Expired due to Term

• Current Assignee: Wearable Technologies Ltd. (Blackline Safety Corp.)
• Original Assignee: Eleksen Limited (Peratech Limited)
• Inventors: Sandbach, David L.
• Primary Examiner(s): Easthom, Karl D.
• Application Number:
  US09/744,155
• Time in Patent Office: 603 Days
• Field of Search: 338/99, 338/101, 338/114, 338/5, 338/47, 338/208, 338/210
• US Class Current: 338/208
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: H01H 2203/0085 Layered switches integrated into garment, clothes or textile
• CPC Class Codes: H01H 2203/01 Woven wire screen
• CPC Class Codes: H01H 9/0235 specially adapted for remote control, e.g. of audio or video apparatus

Abstract

A position sensor is arranged to detect the position of a mechanical interaction, such as the application of manual pressure. A first fabric layer has electrically conductive fibers machined therein to provide a first conductive outer layer allowing conduction in all directions along the layer. A second fabric layer has electrically conductive fibers machined therein to provide a second conductive outer layer allowing conduction in all directions along the layer. A central layer is disposed between the first outer layer and the second outer layer. The central layer includes conductive elements. A first insulating separating element is disposed between the first conductive outer layer and the conducting elements. A second insulating separating element is disposed between the second conductive outer layer and the conducting elements. The conducting elements provide a conductive path between the first conducting outer layer and the second conducting outer layer at the position of a mechanical interaction.

Claims

1. A position sensor for detecting the position of a mechanical interaction, said sensor including:

a first fabric layer having electrically conductive fibres machined therein to provide a first conductive outer layer allowing conduction in all directions along the layer;

a second fabric layer having electrically conductive fibres machined therein to provide a second conductive outer layer allowing conduction in all directions along the layer;

a central layer disposed between said first outer layer and said second layer, said central layer including conducting means;

a first separate insulating layer disposed between said first conductive outer layer and said central layer; and

a second separate insulating layer disposed between said second conductive outer layer and said central layer;

wherein said conducting means provides a conductive path between said first conducting outer layer and said second conducting outer layer at the position of a mechanical interaction, and said position sensor has electrical connections to the first and second conductive outer layers only.

2. A position sensor according to claim 1, wherein said central layer is a fabric layer which has a different compressibility than that of said outer fabric layers.

3. A position sensor according to claim 1, wherein the conductivity of said outer layers is anisotropic.

4. A position sensor according to claim 3, wherein said outer fabric layers include insulating fibres and said anisotropic conductivity is defined by ratios of conductive fibres to insulating fibres.

5. A position sensor according to claim 1, wherein the electrical resistance between said conductive outer layers is indicative of the pressure applied to the position sensor at a mechanical interaction.

6. A position sensor according to claim 1, wherein said central layer is a fabric layer comprising insulating fibres.

7. A position sensor according to claim 1, wherein said conducting means are conductive fibres.

8. A position sensor according to claim 1, wherein said central layer is a fabric layer comprising conductive fibres only.

9. A position sensor according to claim 1, wherein said central layer comprises a knitted fabric layer having a compressible structure such that it becomes more conductive when it is compressed.

10. A position sensor according to claim 1, wherein said central layer is a fabric layer comprising a mixture insulating and conductive fibres.

11. A position sensor according to claim 1, wherein said central layer is a fabric layer produced from a yarn having insulating fibres twisted together with a conductive fibre.

12. A position sensor according to claim 11, wherein said conductive fibre is less flexible than said insulating fibres, so that said conductive fibre is recessed below the general profile of the insulating fibres.

13. A position sensor according to claim 1, wherein said first insulating layer comprises a first insulating fabric comprising insulating fibres, and said second insulating layer comprises a second insulating fabric comprising insulating fibres.

14. A position sensor according to claim 1, wherein said first outer conductive layer has two electrical connectors configured to allow an electrical potential to be applied across said first outer conductive layer during position detection.

15. A position sensor according to claim 14, wherein said first outer conductive layer is anistropic such that when an electrical potential is applied between said electrical connectors to generate a voltage gradient, said first outer conductive layer is most conductive in a direction perpendicular to said voltage gradient.

16. A position sensor according to claim 1, wherein insulating functionality is provided by said central layer for which the yarn of said central layer has a conducting fibre and insulating fibres, and said conducting fibre is recessed below the profile of the insulating fibres.

17. A method of detecting the position of a mechanical interaction with a position sensor, wherein said position sensor has:

a first fabric layer with electrically conductive fibres machined therein to provide a first conductive outer layer allowing conduction in all directions along the layer;

a second fabric layer with electrically conductive fibres machined therein to provide a second conductive outer layer allowing conduction in all directions along the layer;

a central layer disposed between said first outer layer and said second outer layer and including conducting means;

a first separate insulating layer disposed between the first conductive outer layer and the central layer; and

a second separate insulating layer disposed between said second conductive outer layer and said central layer;

wherein said method comprises;

providing electrical connections to the first and second outer layers only;

applying an electrical potential to the first outer conducting layer;

applying a force to said position sensor, such that the conducting means provides a conductive path between said first conducting outer layer and said second conducting layer at the position of the force; and

measuring an electrical potential appearing on the second outer conducting layer.

18. A method according to claim 17, wherein the conductivity of said outer layers is anisotropic.

19. A method according to claim 17, wherein insulating functionality is provided by said central layer for which the yarn of said central layer has a conducting fibre and insulating fibres, and said conducting fibre is recessed below the profile of the insulating fibres.

20. A method according to claim 17, wherein said central layer comprises insulating fibres wrapped around a conducting fibre of a relatively larger diameter such that the extremities of resulting yarn provide insulating separating means.

21. A position sensor for detecting the position of an applied mechanical interaction, said mechanical interaction having an area and a force, said sensor comprising:

a first fabric layer having conductive fibres machined therein to provide a first conductive outer layer;

a second fabric layer having conductive fibres machined therein to provide a second conductive outer layer,

a compressible inner layer disposed between said first fabric layer and said second fabric layer comprising a plurality of conductive fibres such that a conductive path is provided through said fibres when said compressible inner layer is placed in compression;

a first separate insulating layer disposed between the first conductive outer layer and the compressible inner layer; and

a second separate insulating layer disposed between said second conductive outer layer and said compressible inner layer;

wherein said position sensor has electrical connections to the first and second conductive outer layers only.

22. A sensor according to claim 21, wherein the conductivity of at least one of said fabric layers is anisotropic.

23. A sensor according to claim 22, wherein said anisotropic fabric layer is manufactured by using different material types for warps and wefts of said fabric layer.

24. A sensor according to claim 22, manufactured from a warp and weft of similar fibres wherein the ratio of conductive to non-conductive fibres in said weft is different to the ratio of conductive to non-conductive fibres in said warp.

25. A position sensor according to claim 21, wherein said central layer is a fabric layer comprising insulating fibres.

26. A position sensor according to claim 21, wherein said conducting means are conductive fibres.

27. A position sensor according to claim 21, wherein said central layer comprises a knitted fabric layer having a compressible structure such that it becomes more conductive when it is compressed.

28. A position sensor according to claim 21, wherein said first insulating layer comprises a first insulating fabric comprising insulating fibres, and said second insulating layer comprises a second insulating fabric comprising insulating fibres.

29. A position sensor according to claim 21, wherein said first outer conductive layer as two electrical connectors configured to allow an electrical potential to be applied across said first outer conductive layer during position detection.

30. A position sensor according to claim 29, wherein said first outer conductive layer is anistropic such that when an electrical potential is applied between said electrical connectors to generate a voltage gradient,

said first outer conductive layer is most conductive in a direction perpendicular to said voltage gradient.

31. A position sensor according to claim 21, wherein insulating functionality is provided by said central layer for which the yarn of said central layer has a conducting fibre and insulating fibres, and said conducting fibre is recessed below the profile of the insulating fibres.