GB2461712A

GB2461712A - Advanced fabric control switch

Info

Publication number: GB2461712A
Application number: GB0812543A
Authority: GB
Inventors: Dianne Clare Jones; Steven Leftly
Original assignee: SENTRIX Ltd
Current assignee: SENTRIX Ltd
Priority date: 2008-07-09
Filing date: 2008-07-09
Publication date: 2010-01-13
Also published as: GB0812543D0

Abstract

Switches for use in soft or textile articles constructed of a minimum of 2 layers and using multiple parallel soft contacts which must be pressed simultaneously to activate the switch. In the embodiment shown Electrodes (1.1, 9, 1*) are embedded within the fabric Electrode Member (2). The Electrodes (1.1, 9, 1*) are shielded within the Electrode Member (2) except where they are exposed at the surface of the Electrode Member at Contact Points (8). The Conductor Plane (3) is a woven fabric with alternating stripes of electrically conductive yarns and nonconductive yarns. The Contact Points (8) are located in a Switch Zone (4). When the device is pressed, the Conductive zones on the Conductor plane fabric (3) bridge Electrodes (1.1) and (9), and then (9) and (1*), closing the switch circuit between Electrodes (1.1) and (1*).

Description

Advanced Fabric Contact Switch

Background

This invention relates to the use of switches where flexibility and low profile is required. Current low profile switch technology utilises hard or semi rigid printed circuit boards (PCB5) and wires or cables. These types of switch and sensor systems have limited use in soft, textile or flexible environments that often require high durability to mechanical forces such as bending and/or stretching. Conventional low profile switch technology is also not durable for repeated exposure to wet environments (such as laundering and dry cleaning) Some current fabric switching systems using resistance-based pressure sensor mechanisms as switches are prone to false triggering, are complex structures, and cannot be manufactured economically. These fabric technologies tend to rely on many fabric layers which are difficult to manufacture and are not necessary for this invention. This invention uses direct contact and bridging switching methods with unique construction of fabrics and separate PCB elements to solve these problems.

Description

This invention allows for the production of large volumes of an economical keypad or switch system (the Device) using flexible and fabric materials. Electronic keypads and switches already exist whereby a conductive rubber switch-making' contact actuator is fixed on top of a hard PCB. This invention differs to this type of device since different materials are used to allow the contact switch system to be flexible or soft in nature and be suitable for incorporation into a soft or flexible environment. The preferable device uses mainly textile fabric materials. A key feature is also that contact of conductive elements must take place simultaneously at several locations to make the switch. This method is unique within fabric and flexible switching technology and is designed to make it difficult to accidentally activate the switches. This is because pressure must be applied in multiple locations simultaneously to activate a switch. Another unique feature is that PCB elements fixed to the device are used to give the switches specific resistance output which can be used to digitally assign switch functions and allow arrays of switches to be connected using a 2-pinout configuration.

The device comprises of several main components; A flexible conductor plane (Conductor Plane), a flexible preformed electrode member (Electrode Member), a spacer material (Spacer), and a PCB element (PCB element) to give several desired and described repeatable electronic properties.

This Conductor Plane is a flexible material, preferably a fabric which has lateral zones of conductive and non-conductive yarns.

The material can also be electrically conductive rubber moulded or extruded in a generally flat, preformed shape so as to form an electrically conductive sheet.

The Electrode Member is a flexible preformed structure containing a number of separate electrically conductive tracks (Electrodes) The Electrodes are generally shielded within the Electrode Member but become exposed at specific designated positions (Contact Points) along the Electrode Member so as to correspond with specific designated positions or Switch Zones'.

The Spacer is a material designed to keep the Conductor plane and Contact Points apart until pressure is applied. This materia] is preferably a polymer sheet with slits or holes, or a mesh fabric with holes.

The Conductor Plane is placed over the Electrode Member and Spacer and when sufficient force is exerted at each of the Switch Zones/Contact Points the circuit is closed when the Conductor Plane bridges the Electrodes within the Electrode Member. The circuit can be closed by two methods; a) A force causing the Conductor Plane to make contact with two Contact Points simultaneously.

b) A force causing the Conductor Plane to make contact with three Contact Points simultaneously. With this method lateral conductive tracks on the Conductive Plane separate the sets of Contact points to ensure they are not bridged until all three Contact points are pressed.

These switches use parallel electrical contact points which prevent false activation of the switches. This means that at least two points of electrical contact must be made simultaneously to make a single switch. For extra protection from false triggering, the design can also be used where three points of electrical contact must be made to make a single switch. In this example a bridge must be made between Contact points 1 & 2 and between Contact points 2 & 3 simultaneously to close the switch.

Another key feature of the invention is that a PCB is attached on the Electrode Member so that the switch signals can be modified and separated into several analogue signals for processing on a separate electronic device. In particular the PCB has separate resistors assigned to each switch with fixed values for each switch zone. Each switch zone has a separate resistor and when a switch is made the downstream resistance value for that switch is fixed. This allows for multiple switches on keypad to terminate with a two pin output. Each switch gives a different fixed resistance such as Ri, R2, R3 etc., and these can be processed on a separate device to give a repeatable electronic response form each switch.

Other layers may be bonded above the Conductor Plane and/or below the Electrode Member. These layers may be of a textile, gel, foam, film, po]ymer or other soft/flexib]e materia] to the give the device specific properties such as tactility, protection from abrasion/wear and/or to make it suitable for sewing. The Conductor Plane and Electrode Member may also be encapsulated in a polymer material using compression, injection or other moulding techniques to create a flexible contained device that may also be waterproof or resistant to moisture or chemicals or other harsh environments.

The Electrode Member and Electrodes may be constructed from the following: * textile fabric containing metallic fibre conductors woven, knitted, braided or laid in the structure.

* flexible flat cable (FFC) containing metallic foil strips laminated with polymer shielding in a flat strip film.

* textile fabric containing wires woven, knitted or laid in the structure.

* flexible film or fabric with printed or coated electrically conductive tracks.

* any combination of the above.

The Electrode Member may contain any number of Electrodes within the above structure. The Electrodes may be aligned to correspond with an industry standard termination method and are usually spaced at 2.54mm or 1.25mm apart.

The Conductor Plane may be constructed using the following methods: * woven or knitted fabric containing electrically conductive and non-conductive yarns * moulded electrically conductive rubber (preferably Wacker LR3162 silicone rubber) panels manufactured using injection or compression or other moulding techniques.

* moulded electrically conductive rubber bonded onto flexible materials (such as textile materials or flexible films) * electrically conductive rubber coated onto a flexible material.

* electrically conductive rubber bonded to non-conductive rubber in sheet form.

If moulded, the Conductor Plane may have integral shapes formed within the structure such as domes, rubber dots or nodules and/or hollow regions.

The Contact Points of the Device can be constructed using the following methods: * a metallic wire or yarn exposed from the shielded section of the Electrode Member (such as Du Pont -Aracon or Silver coated nylon yarn) . At the Contact Point this wire or yarn may be raised at the surface of the structure to allow electrical contact.

* a metallic contact component that is attached to the Electrode Member at specific locations using a tool (such as a crimp termination component e.g. Nicomatic Crimplex crimp contacts) * an electrically conductive material printed or coated on the Electrode Member.

The Conductor Plane is fixed to the Electrode Member using one of the following methods: * the Conductor Plane may be sewn onto the Electrode Member.

* the Conductor Plane may be bonded or glued onto the Electrode Member.

* the Conductor Plane may be fixed onto the Electrode Member using hard attachment methods such as rivets, snaps, studs, zips or other commonly used textile fixtures.

The Device may be encapsulated using any or all of the following methods: * the Device may be bonded between further layers of fabrics or flexible films.

* the Device is placed into an injection tool during the moulding process and becomes part of an injection moulded article.

* the Device is coated with a gel, polymer or polymer foam material to provide certain tactile or other properties.

* the Device has a layer of switch domes bonded on top of or underneath the Conductor Plane that correspond with the Contact Points to provide tactile/haptic feedback or a sound when a switch is pressed.

* the Device is attached to another piece of fabric using adhesive seam tapes commonly used in the garment construction industry.

* the Device is attached to another fabric article using a removable system such as Velcro.

The Device can be connected to further electronics using several methods: * attaching crimp contacts to the ends of the Electrodes using a tool (such as those used in the FFC/FILexibILe printed circuit industry) . These crimp contacts may then be connected to a mating connector or soldered onto a PCE member or connector.

* attaching textile based connectors to the ends of the Electrodes such as snaps, rivets or other textile fixtures.

* soldering wires directly onto the Electrodes.

* attaching the Electrodes to secondary Electrode Member by way of sewing, adhesives or other fastening system.

Advantages over existing technologies: * the Devices embodied in this invention can be manufactured very economically because of the small number of simple easily assembled parts.

* since all these parts are flexible or soft in nature the Devices can be used as switches or sensors in a large number of applications for example but not limited to: wearable electronics, textile switches/sensors, automotive seat switches or sensors, automotive interior switches or sensors, domestic interior switches or sensors, under floor switches or sensors, toy switches or sensors, medical switches or sensors, switches or sensors positioned on the human body.

* The bridging switch design allows for a Device to be made with as few as two fabric layers whilst preventing accidental switch activation.

* The Conductor Plane and the Electrode Member can both be manufactured using continuous processes such as moulding and weaving respectively and therefore can be economically produced in large volume.

* Single or multiple switches can be made from the same components.

* all the Electrodes used in the Devices are pre-ILaid within a single structure and are therefore easy to terminate and connect to whilst proving the minimal amount of further connections that are prone to failure.

Description of the drawings

Figure la This drawing represents a top view of one example of a single switch Device containing three Electrodes (1.1, 9, 1*).

The Electrodes (1.1, 9, 1*) are embedded within the fabric Electrode Member (2) The Electrodes (1.1, 9, 1*) are shielded within the Electrode Member (2) except where they are exposed at the surface of the Electrode Member at Contact Points (8) Contact Points (8) are on separate parallel Electrodes (1.1, 9, 1*) . The Conductor Plane (3) is a woven fabric with alternating stripes of electrically conductive yarns and non-conductive yarns.

This fabric is positioned on top of the Electrode Member and is permanently fixed to the Electrode Member with thermal adhesive film. In its resting state there is no contact between the Conductor Plane (3) and Contact Points (8) The Contact Points (8) are located in a Switch Zone (4) When the device is pressed, the Conductive zones on the Conductor plane fabric (3) bridge Electrodes (1.1) and (9), and then (9) and (1*), closing the switch circuit between Electrodes (1.1) and (1*) Figure lb This figure shows a circuit diagram of the circuit between Electrodes (1.1) and (1*).

Figure ic This figure shows a woven Conductor Plane (3) with alternating rows of conductive yarns (5) and non-conductive yarns (6) Therefore this fabric has horizontal conductivity but not vertical conductivity.

Figure 2a This figure shows a top view of an assembled single switch device.

It can be seen that the conductive fabric zones (5) of the fabric (3) can bridge Electrodes (1.1) and (9), and then separately Electrodes (9) and (1*) Figure 2b This figure shows an end view of the Device shown in Figure 2a in resting state. A mesh (12) is separating the layers of the Conductor Plane (3) and the Electrodes (1.1, 9, 1*).

Figure 2c This figure shows an end view of the Device shown in Figure 2a with a force (13) pressing on the device over the Electrode Contact Points (1.1, 9, 1*) . The Conductor Plane (3) is in contact with all three Electrode Contact Points creating a conductive bridge from Electrode (1.1) to (1*) Figure 3a This figure shows a multi switch design of the Device shown in Figure 2a. There two sets of three Contact Points (8) sharing a common ground Electrode (1*) . Pressing on the upper Switch Zone (4) creates a bridge between Electrodes (1*) and (1.2) . Pressing on the lower Switch Zone (4*) creates a bridge between Electrodes (1.1) and (1*) Figure 3b This figure shows the device with a PCB Element (10) attached on the Electrode Member. The PCB Element contains resistors to give separate fixed resistance output on Electrodes (1.1) and (1.2).

This enables the two switches to be differentiated when connected to an analogue/digital converter or electronic processor.

Figure 3c This figure show a circuit diagram of the switch device shown in Figure 3b.

Figure 4a This drawing represents a top view of one example of a single switch Device containing two Electrodes (1.1, 1*) . The Electrodes (1.1, 1*) are embedded within the fabric Electrode Member (2) . The Electrodes (1.1, 1*) are shielded within the Electrode Member (2) except where they are exposed at the surface of the Electrode Member at Contact Points (8, 8*) . Contact Points (8, 8*) are on separate parallel Electrodes (1.1, 1*). The Conductor Plane (3) is a woven fabric with alternating stripes of electrically conductive yarns and non-conductive yarns. This fabric is positioned on top of the Electrode Member (2) and is permanently fixed to the Electrode Member with thermal adhesive film. In its resting state there is no contact between the Conductor Plane (3) and Contact Points (8, 8*) . The Contact Points (8, 8*) are located in a Switch Zone (4) . When the device is pressed, the Conductive zones on the Conductor plane fabric (3) bridge Electrodes (1.1) and (1*), closing the switch circuit between Electrodes (1.1) and (1*).

Figure 4b This figure shows a circuit diagram of the circuit between Electrodes (1.1) and (1*).

Figure 4c This figure shows an end view of the Device shown in Figure 4a in resting state. A mesh (12) is separating the layers of the Conductor Plane (3) and the Electrodes (1.1, 1*).

Figure 4d This figure shows an end view of the Device shown in Figure 4a with a force (13) pressing on the device over the Electrode Contact Points (1.1, 1*). The Conductor Plane (3) is in contact with both Electrode Contact Points (8, 8*) creating a conductive bridge from Electrode (1.1) to (1*) Figure 5a This figure shows a multi-switch version of the device shown in Figure 4a. This device has five separate switch zones (4) each containing a pair of parallel Contact points (8) . Each pair of Contact Points (8) has a switch Electrode (1.1) and a common Electrode (1*) . This design allows for a two switch electrodes to share a common electrode to minimise the number of electrode tracks. In this device the Electrode Member (2) is terminated with metal crimp contacts (11) sO that the Electrode ember may be connected to a PCB or electronic connector housing.

Figure 5b This figure shows a Device similar to that shown in Figure 5a but with a PCE member (10) attached on the Electrode Member (2) . The PCB Element contains resistors to give separate fixed resistance output on the five switch Electrodes. This enables the five switches to be differentiated when connected to an analogue/digital converter or electronic processor. A jack connector (13) is used to plug the device into another electronic device.

Figure 5c This figure shows a circuit diagram of the electronic circuit between the five switch Electrodes and the common Electrodes in the Electrode Member (2) . Each switch Electrode is assigned a separate resistor Ri, R2...R5.

Claims

Claims 1. A switch for use in a soft article, such as a textile article, comprising: a fabric conductor carrier having a plurality of parallel electrical conductors; and a flexible contact maker comprising an electrically conductive substrate, the flexible contact maker being disposed adjacent to the conductor carrier; wherein the contact maker is configurable in either a first configuration in which it electrically connects at least two of the electrical conductors simultaneously or a second configuration in which it does not electrically connect the electrical conductors, the contact maker being resiliently biased in at least one of the first and second configurations.
2. A switch according to claim 1, wherein the contact maker forms part of a contact layer.
3. A switch according to claim 1 or 2, wherein the electrical conductors are electrically shielded from the contact maker except at exposed contact points.
4. A switch according to claim 3, wherein the contact maker makes contact with two of the electrical conductors at two contact points on parallel separate electrical conductors when in the first configuration.
5. A switch according to claim 3, wherein the contact maker makes contact with three of the electrical conductors at three contact points on parallel separate electrical conductors when in the first configuration.
6. A switch according to any preceding claim, wherein the electrically conductive substrate of the contact maker is electrically conductive textile fabric.
7. A switch according to any preceding claim, wherein the electrically conductive substrate of the contact maker is an electrically conductive rubber.8. A switch according to any preceding claim where the electrical conductors are silver coated nylon yarns.
8. A switch according to claim 4 or 5 where a PCB is attached to the conductor carrier to modify the electrical conductor contact resistance when in the first configuration.
9. A switch according to claim 8 where the PCB contains fixed value resistors to modify the electrical conductor contact resistance when in the first configuration.
10. A switch according to claim 9 where the fixed resistor values for the switches are 5.6K, 10K, 20K, 31.6K and 47K.
11. A switch according to any preceding claim, wherein the outer surface of the contact maker is bonded or stitched to a flexible film or fabric.
12. A switch according to any preceding claim, wherein the conductor carrier and the flexible contact maker conform to an uneven surface.
13. A switch according to any preceding claim, wherein the conductor carrier and the flexible contact maker are encapsulated in a polymer material.