Detector constructed from fabric

• US 6,714,117 B2
• Filed: 07/24/2002
• Issued: 03/30/2004
• 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:
  US10/201,279
• Publication Number:
  US 20020180578A1
• Time in Patent Office: 615 Days
• Field of Search: 338/208, 338/5, 338/47, 338/99, 338/101, 338/114, 338/210
• US Class Current: 338/101
• 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, 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 first connector providing electrical connection to said first outer conductive layer to allow the application of a first electrical potential;

a second connector providing electrical connection to said first outer conductive layer to allow the application of a different second electrical potential;

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 third connector providing electrical connection to said second outer conductive layer to allow the measurement of an electrical potential on said second layer;

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

a first insulating separating means disposed between said first conductive outer layer and said conducting means; and

a second insulating separating means disposed between said second conductive outer layer and said conducting means;

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

2. A position sensor as in claim 1 wherein said first insulating means has insulating fibres included in the first fabric layer and said second insulating means has insulating fibres included in the second fabric layer.

3. A position sensor as in claim 2 wherein said insulating fibres form yarns of a greater average diameter than said conductive fibres.

4. A position sensor as in claim 1 wherein said first and second insulating means have insulating fibres included in the central layer and said conducting means comprises of conductive fibres.

5. A position sensor as in claim 4 wherein said insulating fibres are of greater average diameter than said conductive fibres of said conducting means.

6. A position sensor as in claim 1 wherein said first and second insulating means have insulating fibres included in the central layer and said conducting means comprises a plurality of conducting elements.

7. A position sensor as in claim 1 wherein said central layer has a different compressibility to said outer fabric layer.

8. A position sensor as in claim 1 wherein the conductivity of said outer layers is anisotropic.

9. A position sensor as in claim 8 wherein said outer fabric layers include insulating fibres and said anisotropic conductivity is defined by ratios of conductive fibres to insulating fibres.

10. A position sensor as in 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.

11. A position sensor as in claim 1 wherein the electrical resistance between said conductive outer layers is indicative of the size of an area of the position sensor affected by a mechanical interaction.

12. A position sensor according to claim 1, wherein said sensor includes a fourth connector providing a second electrical connection to said second outer conductive layer.

13. 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 first connector providing electrical connection to said first outer conductive layer to allow the application of a first electrical potential;

a second connector providing electrical connection to said first outer conductive layer to allow the application of a different, second electrical potential;

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 third connector providing electrical connection to said second outer conductive layer to allow the measurement of an electrical potential on said second layer;

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

a first insulating separating means disposed between the first conductive outer layer and said conducting means; and

a second insulating separating means disposed between said second conductive outer layer and said conducting means;

wherein said method comprises the steps of;

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

applying an electrical potential gradient across said 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 outer layer at the position of the force; and

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

14. A method as in claim 13 wherein the conductivity of said outer layers is anisotropic.

15. A method as in claim 13 wherein insulating regions of adhesive with gaps therebetween hold said assembly together and provide said insulating means.

16. A method as in claim 13 wherein said outer layers have insulating yarns with a diameter larger than conducting fibres such that the functionality of said insulating layer is provided by the insulating yarns of said outer conducting layers.

17. A method as in claim 13 wherein conducting fibres of said central layer are grouped into conducting islands separated by regions of substantially higher resistivity.

18. A method as in claim 13 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.

19. A method as in claim 13 wherein said insulating means is provided by said central layer comprising insulating fibres wrapped around a conducting fibre of a relatively larger diameter such that the extremities of resulting yarn provide the insulating separating means.

20. A method as in claim 13 wherein the functionality of said insulating separating means is provided by the central layer having both conducting and non-conducting elements such that, in its normal configuration, said conducting elements are separated such that conduction between said outer layer is not possible and wherein said conduction is made possible on the application of compressive force.

21. A method as in claim 13 wherein a central layer is configured from an elastomeric material and conducting fibres are embedded therein, wherein said elastomeric material provides the insulating functionality of the insulating separating means.

22. A method as in claim 13 wherein a substantially incompressible conductive material is placed between insulating material of said central layer, thereby fabricating a detector particularly sensitive to area of interaction.

23. A method as in claim 13 wherein a central conductive layer has a substantially open weave into which conductive adhesive or ink is applied thereto.

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

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

a first connector providing electrical connection to said first outer conductive layer;

a second connector separate to said first connector, said second connector providing electrical connection to said first outer conductive layer,

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

a third connector providing electrical connection to said second outer conductive layer to allow the measurement of an electrical potential on said second layer; and

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

wherein said position sensor has electrical connections to the first and second conductive outer layers only, and said compressible inner layer is configured such that when a first electrical potential is applied to said first connector and a different second electrical potential is applied to said second connector, the electrical potential measured at said third connector provides an indication of the position of mechanical interaction on said position sensor.

25. A sensor as in claim 24 wherein said inner layer is a non-woven fabric having insulating fibres and short conductive fibres, wherein the length of said conductive fibres is less than the thickness of the inner layer.

26. A sensor as in claim 24 wherein said conductive fibres or particles are held within a substantially continuous insulating material.

27. A sensor as in claim 24 wherein the conductivity of at least one of said fabric layers is anisotropic.

28. A sensor as in claim 27 wherein said anisotropic fabric layer is manufactured by using different material types for warps and wefts of said fabric layer.

29. A sensor as in claim 27 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.

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

a first fabric layer having conductive fibres machined therein to provide a first conductive layer,

a second fabric layer having conductive fibres machined therein to provide a second conductive layer;

a third fabric layer having conductive fibres machined therein to provide a third conductive layer;

a compressible inner layer disposed between said first fabric layer and said second fabric layer comprising a plurality of conductive fibres or particles such that a conductive path having a conductivity dependent upon the force and the area of a mechanical interaction is provided through said fibres or particles when said compressible inner layer is placed in compression; and

a second inner layer disposed between said second fabric layer and said third fabric layer, and comprising conducting means configured to provide a conductive path having a conductivity dependent upon the area of the mechanical interaction and relatively unaffected by changes in force.

31. A position sensor according to claim 30, comprising

a first connector providing electrical connection to said first fabric layer;

a second connector providing electrical connection to said second fabric layer;

a third connector providing electrical connection to said third fabric layer;

said position sensor has electrical connections to the first, second and third fabric layers only, and is configured such that when a mechanical interaction having an area and a force is applied to said sensor;

when a first electrical potential is applied to said first connector and said second connector is connected to ground via a resistor, the electrical potential measured at said second connector provides a first value related to the area of said mechanical interaction; and

when a second electrical potential is applied to third first connector and said second connector is connected to ground via a resistor, the electrical potential measured at said second connector provides a second value related to the product of the force and the area of said mechanical interaction;

such that;

when said second value is divided by said first value a third value related to the force of said mechanical interaction is determined.