WO2015185879A1

WO2015185879A1 - Method and apparatus for forming a wire structure

Info

Publication number: WO2015185879A1
Application number: PCT/GB2014/051694
Authority: WO
Inventors: Ronald Peter Binstead
Original assignee: Ronald Peter Binstead
Priority date: 2014-06-03
Filing date: 2014-06-03
Publication date: 2015-12-10
Also published as: GB2541336B; GB2541336A; GB201620528D0

Abstract

A method for forming a structure with wire elements (16) using a wire depositing device with a tube (26) for laying a wire (16), the method comprising: providing a substrate (22) with an adhesive surface (24); feeding a free end of the wire (16) through the tube (26) of the wire depositing device; and drawing the tube (26) laterally across the adhesive surface (34) in a pattern such that the free end of the wire (16) adheres to the adhesive surface (34) and the lateral movement causes the wire (16) to be drawn through the tube (26) and deposited as a trail in accordance with the pattern drawn by the tube (26) crossing the substrate (22).

Description

Method and Apparatus for Forming a Wire Structure

This disclosure relates to a manufacturing technique and apparatus for forming a touch sensor. In particular, although not exclusively, the method relates to encapsulating wire in a thin flexible film for use in touch screens.

Wires-based structures may be provided for a number of different types of applications, including:

capacitive proximity sensing - in capacitive touchscreens, touch pads and keypads; for capacitive near field communication (NFC), or in a proximity sensing camera; inducti e circuits - for detecting conductive objects such as a metal stylus, in near field communication (NFC) or no-contact power transmission applications;

display mechanisms when used in conjunction with embedded electroluminescent material, for example zinc sulphide doped with copper;

heating - to eliminate condensation or to melt ice on a surface or to warm-up a nearby surface; or

any combination of the above applications.

Some wire-based structures are flexible in order to suit their chosen application. Such structures may be encapsulated in films to provide a product such as a touch sensor. The product may be attached to another surface, which can be either flat or curved, to allow detection through the other surface.

Some of the advantages of using fine wire as a touch element in a touch screen or touch pad (instead of indium titanium oxide (ITO) track, for example) are listed below.

1) Wire touch screens may be constructed relatively simply - the use of wire may eliminate many stages used in standard manufacture using ITO.

2) Wire is a readily available, standard, low cost material.

3) Wire is strong and may provide flexibility; this makes a wire structure suitable for wearable electronics - the end product may be rolled up, stretched, vacuum formed, and may even be creased without loss of functionality.

4) Wire may have a very low resistivity, therefore enabling very large (over 3 metres long) devices to be provided and allowing a connector to be situated a long distance away from a sensing zone.

5) Wire is readily adaptable to "roll to roll" processing.

6) Low cost and readily available manufacturing equipment may be used to handle wire.

7) Wire structures can be very rapidly prototyped and their design modified (or customised); new designs may be available in a few minutes or hours, and can sometimes be provided using a simple software modification.

9) A touch screen may be provided that is transparent up to all its edges without the need to provide a bezel at the edge because a transparent substrate for the wire can be used.

10) A touch pad with more than 2 axes of wiring can be implemented with wires 60 degrees between the axes, three dimensions of wiring is readily manufactured with the same simple technology. Wiring with 3 axes enables two fingers to be detected without ambiguity when using "self capacitance" as a means of detection. At 45 degrees of separation there are four dimensions, or axes of wire. In general, the separation for number, n, of axis is 360/2n degrees.

US 5844506, granted to Ronald Peter Binstead, describes a touchpad with wire sensing elements for multi-touch sensing. The touchpad comprises an electrically insulating membrane (10) with a first series of spaced apart conductors (12) on a first face of said membrane (10) and a second series of spaced apart conductors (14) on or proximal thereto, in which there is no electrical contact between said first and second series of conductors (12,14), each conductor of said first and second series of conductors being sensitive to the proximity of a finger to modify the capacitance of said conductor to detect the presence of the finger positioned close to that conductor and in which said first and second series of conductors (12, 4) comprise enamel coated wires having a diameter in the range of about 0 microns to about 25 microns to be substantially invisible when the touchpad is used as a touch screen.

According to a first aspect of this invention there is provided a method for forming a structure with wire elements using a wire depositing device with a tube for laying a wire, the method comprising:

feeding or threading a free end of the wire through the tube of the wire depositing device; and

drawing the tube laterally across an adhesive surface of a substrate in a pattern such that the free end of the wire adheres to the adhesive surface and the lateral movement causes the wire to be drawn through the tube and deposited as a trail in accordance with the pattern drawn by the tube crossing the substrate. The method may be used to embed wire in a controlled and well defined pattern in a flexible plastic film. The method may also provide robust terminations for connection to suitable controlling or sensing circuitry. The structure may be a touch pad, such as an inductive or capacitive touch screen or touch pad, or the structure may be a near field communication device structure

The depositing device may comprise a pen plotter-type apparatus. The pattern may follow a first route from a termination zone, then through a transition zone, then through a sensing zone of the touch pad, before returning, via a transition zone, to the termination zone. This process may be repeated, and may provide a first array of wire elements using a single wire. The wire elements may be touch elements and may provide sensing/receiving or controlling/transmitting elements in the sensing zone.

The pattern may follow a first route from a termination zone through a sensing zone of the touch pad in order to provide a first touch element. The pattern may follow a second route which runs from the same, or an alternative termination zone, through the same, or an alternative transition zone, then through the sensing zone in order to provide a second array of wire elements. The pattern may follow a third route which runs from the same, or an alternative termination zone, through the same, or an alternative transition zone, then through the sensing zone in order to provide a third array of wire elements.

The pattern may follow a first route from a termination zone, optionally then through a transition zone, then through a sensing zone of the touch pad in order to provide a first array of wire elements. The pattern may follow a second route which runs from the termination zone through the sensing zone in order to provide a second array of wire elements.

The pattern may follow a second route from a termination zone through a sensing zone of the touch pad in order to provide a second touch element. The second array of wire elements may overlap the first array of wire elements. In general, each or all the arrays of wire elements may be transverse to each other and/or each or all the arrays of wire elements may overlap each other. The second array of wire elements may overlap the first array of wire elements. The first array of wire elements may be transverse, or substantially perpendicular, to the second array of wire elements. At least a portion of the wire may comprise an outer coating of insulation configured to prevent direct electrical contact at the cross-over points between the first and second arrays of wires. A joining region may be provided at a periphery of the sensing zone. The method may comprise providing, at a periphery of the sensing zone, an extended region of wire linking two wire elements within the sensing region. Wire elements within the sensing region are connected together by wires in the joining region.

The method may comprise cutting the wire in the joining region, or extended region, in order to provide multiple separate wire elements within the sensing zone. The method may comprise fitting a terminal connector to a termination region at a periphery of the sensing zone in order to enable electrical connections to be made with the wire elements in the sensing zone. The method may comprise laminating the adhesive surface in order to encapsulate the wire elements.

The substrate, adhesive layer and/or laminate may be transparent or translucent.

The tube may have a nib. The method may comprise providing the nib in contact with the adhesive during the drawing step.

The substrate or laminate may comprise a film with a thickness less than 500 or 1000 microns. The substrate or laminate comprises a plastics material or paper. The substrate or laminate may be flexible such that the substrate can form a bent or curved shape in which a tangent to a first portion of the substrate is more than 0 degrees from parallel with a second portion of the substrate.

The method may be at least partially automated. The drawing of the tube laterally across the surface may be controlled by a computer program.

The method may comprise providing electronic circuitry on the substrate. The method may comprise using a plurality of wire depositing devices in parallel to form one or more touch-sensors with wire elements.

According to a further aspect of the invention there is provided a wire depositing device or a computer program configured to perform any method disclosed herein.

According to a further aspect of the invention there is provided a wire depositing device comprising:

a hollow tube for receiving a wire; a nib attached to the hollow tube and configured to lay the wire on an adhesive surface of a substrate;

a holder for holding the tube; and

a driving mechanism attached to the holder and configured to draw the tube laterally across the adhesive surface of the substrate in a pattern such that a free end of the wire adheres to the adhesive surface and the lateral movement causes the wire to be drawn through the tube and deposited as a trail in accordance with the pattern drawn by the tube crossing the substrate.

There may be provided a method of manufacturing a wire depositing device comprising: receiving a pen plotter device comprising a pen, and a holder coupled to a driving mechanism; and

removing an internal drawing mechanism of the pen to provide a hollow tube.

A wire may be fed through the hollow tube of the pen, when in use. The method may further comprise adapting a nib of the pen to allow a wire to be passed through the nib. There may be provided a touch pad or near field communication device manufactured using any method as disclosed herein.

There may be provided a method for creating a very thin "wire-based" flexible multi-touch "self capacitive" and "mutual capacitive" touch-screen using a thin clear adhesive coated plastic film whereupon a modified plotter type pen with one strand of fine insulation coated wire running through it, is drawn sideways across the adhesive coating of the film by a plotter type mechanism, in a pattern, determined by a suitable CAD program, whereby, the effect of the wire sticking to the adhesive coating, and the sideways movement of the pen causes the wire to be drawn through the pen and permanently deposited as a trail showing the pattern of movement of the pen across the film, this trail following a first route which runs from runs from the pen's starting position, through a termination zone along a transition route outside the "sensing zone", and then mainly runs through the "sensing zone" mainly along one axis, leaving a trail of wire representing an x array of touch sensing/receiving or controlling/transmitting elements, returning periodically to the termination zone, whereupon, on completion of the x array, the trail (and) then follows a second route which runs from a termination zone -along the same, or -an alternative transition route outside the "sensing zone", and then mainly runs through the "sensing zone" along an axis which is at right angles to, and runs over, the wire already laid down in the "sensing zone" along the first axis, the overlying wire representing a y array of touch sensing/receiving or controlling/transmitting elements, the insulation preventing direct electrical contact at the cross-over points where the y array parts of the wire run over the x array parts of the wire, whereupon, after periodic returns to the termination zone, and completion of the y array pattern, the pen is returned to its finishing position, which may or may not be the same as its starting position, whereupon, either at this time, or later in the process of manufacture, various positions along the wire are cut resulting in multiple isolated touch sensing/receiving or controlling/transmitting wires running from the termination zone to the x and y axes of the "sensing zone", the process of manufacture being completed by the fitting of a terminal connector and the lamination of the adhesive coated film to another thin clear plastic film with subsequent final trimming.

There may be provided a method for creating a very thin "wire-based" flexible multifunctional inductive sensing/transmitting screen using a thin clear adhesive coated plastic film whereupon a modified plotter type pen with one strand of fine insulation coated wire running through it, is drawn sideways across the adhesive coating of the film by a plotter type mechanism, in a pattern, determined by a suitable CAD program, whereby, the effect of the wire sticking to the adhesive coating, and the sideways movement of the pen causes the wire to be drawn through the pen and permanently deposited as a trail showing the pattern of movement of the pen across the film, this trail following a first route which runs from the starting position of the pen, through a termination zone along a transition route outside the "sensing/transmitting zone", and then runs into the "sensing/transmitting" zone in a pattern determined by the required functionality of the inductive structure, whereby a simple metal or stylus detector might have a simple loop, a near field communication structure might have a simple coil with a few turns in it, and a power transmission or reception structure might have a coil with multiple turns in it, wherein, after this structure has been traced, the pen returns to the termination zone, the process of tracking from the terminal zone, to the sensing/transmitting zone, and returning to the termination zone being repeated a number of times, depending on the number of different inductive structures required, thereafter, the pen returning to its finishing position, whereupon, either at this time or later in the manufacturing process, wires are cut, in the termination zone, resulting in each inductive structure having its own discrete length of wire, both ends of which end at the termination zone, the process of manufacture being completed by the fitting of a terminal connector and the lamination of the adhesive coated film to another thin clear plastic film, with subsequent final trimming.

There may be provided a method for creating a touch-screen using a thin clear adhesive coated plastic film whereupon a modified plotter type pen with one strand of fine wire running through it, is drawn sideways across the adhesive coating of the film by a plotter type mechanism, in a pattern, determined by a suitable CAD program, whereby, the effect of the wire sticking to the adhesive coating, and the sideways movement of the pen causes the wire to be drawn through the pen and permanently deposited as a trail showing the pattern of movement of the pen across the film, the process of manufacture being completed by the cutting of the wire into separate discrete sections, if required, the fitting of a terminal connector and the lamination of the adhesive coated film to another thin clear plastic film.

There may be provided a method for creating a very thin "wire-based" flexible multi-touch "self capacitive" and "mutual capacitive" touch-screen using a thin clear adhesive coated plastic film whereupon a number of modified plotter type pens, each with one strand of fine insulation coated wire running through it, is drawn sideways across the adhesive coating of the film by a plotter type mechanism, one after another, in a pattern determined by a suitable CAD program, whereby, the effect of the wire sticking to the adhesive coating, and the sideways movement of the pen causes the wire to be drawn through the pen and permanently deposited as a trail showing the pattern of movement of the pen across the film, this trail following a route which runs from each pen's starting position, (then) through a termination zone, then along a transition route outside the "sensing zone", fixing each pen, one after another to a single movable bar, this bar then running through the "sensing zone" mainly along one axis, leaving a trail of wire representing an x array of touch sensing/receiving or controlling/transmitting elements, the bar finally returning to its original position but slightly offset in the y axis, wherein each pen is then individually moved, one after the other, back, through the transition zone and the termination zone, to its finishing position.

Substantially the same method may be used for the y - axis. The x - axis may be over plotted by the y - axis. A different set of pens may be used to plot the y axis.

The wire may be enamel coated copper. The wire may be tungsten. The wire may have a diameter range from 5 microns to 50 microns. The wire may have a diameter range from 3 microns to 17 microns.

There may be provided a "no soldering" Capacitive method for terminating enamel coated wires, whereby the wires are first plotted on adhesive coated plastic or paper, in a very tight pattern at the termination point, this pattern then being overprinted with conductive ink, using a stencil, screen printing, or ink-jet printing, a connector terminal then being placed over, and in direct electrical contact with the conductive ink, there being no direct electrical contact between the wire and the connector terminal.

There may be provided a "no soldering" method for terminating bare wires, whereby the wires are first plotted on adhesive coated plastic or paper, in a tight pattern at the termination point, this pattern then being overprinted with conductive ink, using a stencil, screen printing, or ink-jet printing, a connector terminal then being placed over, and in direct electrical contact with the conductive ink.

Terminating wires may be laid down on adhesive coated film. A pcb terminal strip may be placed on the adhesive film before the wire is plotted. The pcb may have conductors facing upward, in such a position whereby, as the wire(s) are plotted they run over the pcb in the places where the conductive traces are found. After the plotting is completed, the wires may be directly soldered to the conductive traces.

A pcb terminal strip may be placed on the adhesive film after the wire is plotted, the pcb having conductors facing downward, in such a position whereby, the plotted wire(s) run under the pcb in the places where the conductive traces are found. The wires may be soldered through the film to the conductive traces.

After the wire(s) have been laid down, a strip of double sided release paper may be temporarily attached to the adhesive film, covering the termination zone. The film may then be laminated to another film. After which, the position where the release film was embedded may be delaminated and the release paper removed. This may allow the pcb terminal strip to be placed, conductive traces facing downward, in such a position whereby, the plotted wire(s) run under the pcb in the places where the conductive traces are found, thereby enabling these wires to be soldered through the film to these conductive traces.

After the film has been laminated to another film, a pcb terminal strip may be stuck to the film with conductive traces facing downward, using double-sided adhesive tape for example, in the terminal area. The pcb conductive traces may be aligned with the wire(s) in the terminal area. The wire(s) then being soldered to the pcb terminal strip, through the two layers of plastic film. There may be provided a method of producing wire embedded touch screens on a roll to roll basis, using the manufacturing methods described in the previous claims, wherein, the adhesive coated film is automatically moved to a new position after each plot is completed, the amount of movement equal to, or greater than the width of the touch-screen being manufactured, the process of plotting a new identical, or different touch screen then beginning again, this whole process repeating until sufficient touch screens have been produced, or until the end of the roll of film.

Immediately after plotting, the newly plotted part of the film may be covered with release paper and rolled onto a new roll until the roll has been completely plotted, or until enough touch screens have been manufactured. Thereafter the roll may be sent through a termination fixing, lamination and touch screen separation process.

The x and/or the y wires may be plotted in loops, outside the sensing area, thereby enabling them to be cut at a later stage, either by scoring the wire with a cutting instrument, or by cutting off the edges of the film which contain the ends of the loops.

A number of identical touch screens may be manufactured at the same time by connecting a number of pens to the same x - y plotting mechanism. Each pen may be spaced apart from its neighbour so that plots do not overlap.

The wire may be laid down in a non-linear or zig-zagged manner in the "sensing/visual" zone. The adhesive coated film may be heat sensitive, enabling the product to be heat/vacuum formed into complex shapes.

The wires may be laid down in a non-linear or zig-zagged manner in areas that will be distorted by heat forming, enabling the wires to straighten out or move without breaking while heat forming takes place.

Two separate films may be used, one for the x - axis and another for the y - axis. One of the films may be laminated, face up, to the other film, which is face down. One of the films may be laminated, face up, to the other film, which is face down. The upper face may have wires laid on it. The downward face may not have wires laid on it. At least one set of wires may have an insulating coating. One of the films may be laminated, face up, to an intermediate insulating film, and the other film may be laminated, face down onto the insulating film. Three separate films may be used, one for the x - axis, another for the y - axis, and a third, intermediate insulating film. One of the films may be laminated, face up, to the intermediate insulating film. Another film may be laminated, face down onto the insulating film. None of the wires may need to have insulating coating.

The adhesive coated film with wire attached may be attached to another surface, which does not use wire as the sensing element. The wired surface may act as a sensor/controller, in one axis, and the other surface may acts as a controller/sensor in the other axis. The "non- wire" material may be a reticulated printed material. The "non- wire" material may be indium tin oxide.

An insulating disc may be inserted at the potential cross-over points between the x - and y - axes after one axis has been plotted and before the second axis is plotted.

An electro-luminescent material may be inserted at the potential cross-over point between the x - and y - axes after one axis has been plotted and before the second axis is plotted.

A haptic material may be inserted at the potential cross-over point between the x - and y - axes after one axis has been plotted and before the second axis is plotted.

The sensing zones may be broken up into several discrete, evenly spaced, or randomly spaced sensing zones. The wires may come together at a common terminal or to separate terminals.

The enamel coating may be dyed a dark colour and/or have low reflectivity.

More than two axes may be plotted. For example, three axes may be plotted.

Two or more non-insulated wires may be plotted on the adhesive film. Two or more non- insulated wires may be electrically joined, if they come within very close proximity to each other, by applying a spot of conductive ink to the conjunction of the two wires. The ink may be applied by any one of various means, such as screen printing, ink jet printing, block printing, or stencilling.

There may be provided a computer program, which when run on a computer, causes the computer to configure any apparatus, including a circuit, controller, touch pad, a near field communications device, a wire depositing device, or any other device disclosed herein or perform any method disclosed herein. The computer program may be a software implementation, and the computer may be considered as any appropriate hardware, including a digital signal processor, a microcontroller, and an implementation in read only memory (ROM), erasable programmable read only memory (EPROM) or electronically erasable programmable read only memory (EEPROM), as non-limiting examples.

The computer program may be provided on a computer readable medium, which may be a physical computer readable medium such as a disc or a memory device, or may be embodied as a transient signal. Such a transient signal may be a network download, including an internet download.

One or more embodiments of the invention will now be described, by way of example only, and with reference to the accompanying figures in which:

Figure 1 illustrates a portion of a wire depositing device;

Figure 2a illustrates a portion of the wire depositing device of figure 1 ;

Figures 2b to 2d illustrate a portion of another wire depositing device;

Figures 2e and 2f illustrate the wire depositing device of figure 2b;

Figures 3a to 3f illustrate a touch pad at different stages in a method of manufacture using multiple wires;

Figures 3g illustrates a touch pad manufactured using a single Wire;

Figure 4 illustrates a connector terminal for the touch pad of figure 3f or 3g;

Figure 5 illustrates a cross section of the touch pad of figure 3f or 3g;

Figure 6 illustrates another touch element arrangement for a touch pad;

Figures 7a to 7c illustrate stages in the formation of a connection terminal;

Figure 8 illustrates various wire structures; and

Figure 9 illustrates a method for forming a structure with wire elements using a wire depositing device with a tube for laying a wire.

Figure 1 illustrates a wire depositing device 10 that has been adapted from a pen plotter device. Pen plotter devices, such as those used in the design industry to render computer aided design drawings, comprise a pen 20 in a holder coupled to a driving mechanism. Only a modified pen 20 of the pen plotter device, and not the holder or driving mechanism, is shown in Figure 1 for clarity. The internal drawing mechanism of the pen 20 (for example a reservoir of ink) has been removed to provide a hollow tube. A metal barrel of the nib of the pen plotter has been removed and the lower end of the remaining hole has been rounded-off (adapted) to form an adapted nib tube 28 to allow a wire 16 to be passed through it without damage from sharp edges, as opposed to exposing ink for drawing onto paper.

The wire depositing device 10 also comprises a stand 12 for holding a conical ended reel 14 of electrically conductive wire, in this example it is enamel coated copper wire 16. The enamel coated copper wire 16 is fed from the reel 14 through a loop 18 of the stand 12 to the modified pen 20 of the modified pen plotter device. The wire may be fed from the loop 18, which is directly above the centre of the reel 14, in order to relieve stress on the wire. The stand 12 therefore provides a stress/strain relief mechanism for the wire 16. The stand 12 may also be resiliently deformable when the wire 16 is in tension.

The enamel coated copper wire 16 is fed through the modified pen 20 onto a temporary resting surface on a plotting surface 22, such as a strip of double sided adhesive tape stuck to an edge of a plotter table. A free end of the wire 16 is held in place (at a periphery of the plotting surface 22, in this example by a piece of masking tape 24. The temporary resting surface may be part of the stand 12 that holds the reel 14 of wire 16.

Figure 2a illustrates a modified pen 20 in greater detail. The modified pen has a barrel, or tube 26 and a nib tube 28, with the original nib of the pen removed. The tube 26 has a first opening at one end to receive wire 16, and a second opening at an opposing end that is in communication with the plotting surface 22, in this example via the nib tube 28.

Protrusions 30 are provided on external surfaces of the tube 26 in order for the pen 20 to slot into a pen holder (not shown) of the pen plotter. The pen tube 26 of Figure 2a is held tight inside the pen holder.

The wire 16 is drawn through the barrel 26 from the reel 14 of Figure 1 and through the nib tube 28 onto the plotting surface 22.

The plotting surface 22 in this example comprises a substrate comprising a plastic film 32 and an adhesive layer 34. The adhesive layer 34 is an outer layer disposed on the plastic film 32, that is, it is adjacent to the nib tube 28 of the pen 20. Wire 16 that has been drawn through the nib 28 sticks to the adhesive layer 34. Downward pressure of the pen-holder forces the wire 16 into contact with the adhesive coating 22. The contact between the wire 16 and the adhesive layer 34 is such that further motion of the pen plotter 20 does not disturb the wire 16 that has already been deposited. Further wire 16 can be drawn through the pen 20 by lateral motion of the pen 20 with respect to the plotting surface 22. In practice, when using very fine wire, the nib tube 28, or tip, of the pen 20 may be in direct physical contact with the adhesive 34 on the plotting surface 22.

The nib 28 may be provided using a different material to the barrel 26 of the pen plotter 20. For example, the nib 28 may be made of a material that does not adhere to the adhesive 34, or adheres weakly to it.

As no "pen-up" movement (where a pen is lifted up from the surface) is required by the pen plotting method, a very simple pen type can be used, which relies on gravity to maintain the pen in the correct vertical position.

Figures 2b to 2d illustrates another "pen" 20 in a housing 50. The pen 20 is similar to that described with reference to figure 2a in that it has a tube 26 and a nib 28. However, in this example the tube 26 and nib 28 are provided as bespoke parts, rather than by adapting a pen of a pen plotter device.

The pen diameter is 6mm to 8mm and the length is about 150mm in this example.

The nib 28 is made of polytetrafluoroethylene (PTFE) in order to prevent or reduce adhesion between the nib 28 and the adhesive 34. An anti-rotation mechanism is provided in order to prevent rotation of the pen 20 with respect to the holder 50. The anti- rotation mechanism comprises a pin 52 mounted on the pen 20. The pin 52 protrudes into a slot 53 (see Figure 2d) in the pen holder 50. Unwanted rotation of the pen is prevented or reduced by the protrusion, or pin 52, which sticks out of one (or more) side(s) of the pen 20 and tracks up and down, freely, within the slot in the pen holder 50.

The holder 50 is mounted on a track 54. The track 54 may be a linear track that can be moved with respect to the plotting surface 22. Alternatively, the track may follow the intended path of the sensing element. The holder 50 is driven along the track 54 by a drive belt 56, in this example. The drive mechanism is therefore configured to draw/move the tube laterally across a surface of the substrate 22. Alternatively, the pen holder may comprise a drive means, such as an electric motor, configured to propel the pen holder 50 along the track 54. Figures 2c and 2d illustrate two views along the cross section of Figure 2b.

Figure 2c shows a cross-sectional view through the line A-B in Figure 2b. A-B is taken through the axis of the pen 20. Figure 2d shows a cross-sectional view through the line C-D which is offset from the axis of the pen 20. The pin 52, which is rigidly attached to the pen 20, sticks out of the side of the pen 20 and protrudes into a slot 53 in the pen holder 50. Unwanted rotation of the pen 20 is prevented or reduced by the protrusion, or pin 52, which extends from one side of the pen 20 and can track up and down, freely, within the slot 53 in the pen holder 50 if the pen 20 moves up and down. A screw 55 is provided as an example of an affixing member for fixedly attaching the holder 50 to the track slider 54.

Figure 2e illustrates the wire depositing device of figure 2b and features such as a stand 12 and spool, or reel 14, of wire 16, which are similar to the features described with reference to figure 1, except that the pen 20, the wire spool 14 and the stress relief mechanism 15 are all attached to the pen holder 50, and can move with the pen holder. The wire 16 is drawn from the reel 14 through a guide 15 and a tube 26 of the pen 20 onto an adhesive layer 36 on the plotting surface 22. The guide 5 performs the stress relief function of the stand 12 and is provided directly above an axis of the reel 14. The stand 12 is connected to the holder 50 by a fixing member 13, which is a nut and bolt in this example, so that the reel 14 moves with the holder 50. Alternatively, the holder 50 may be provided separately from the reel 14 so that it can move relative to the reel.

Figure 2f shows a side view of the wire depositing device of figure 2e.

The wire depositing device described with reference to figures 1 and 2 may be used in a method for forming a structure with wire elements, such as a touch screen, touch sensor, touch pad or near field communication antenna. The method comprises:

providing a substrate with an adhesive surface;

feeding a free end of the wire through the tube of the wire depositing device; and drawing the tube laterally across the adhesive surface in a pattern such that the free end of the wire adheres to the adhesive surface and the lateral movement causes the wire to be drawn through the tube and deposited as a trail in accordance with the pattern drawn by the tube crossing the substrate.

The manufacturing process can utilizes the fact that fine wire readily sticks quite firmly to a "non-setting" adhesive coated film, and may be readily and rapidly pulled off a conical spool with much less tension than is needed to break the wire. As the wire is pulled off the spool it can be twisted, but the adhesion of the wire to the film is strong enough to withstand this twisting, without the wire lifting off the film. Tungsten wire is typically much stiffer than copper wire and so, tungsten wire may start to lift off the adhesive if the wire diameter is too great. If, as illustrated in Figure 1 , fine wire is passed from a vertical reel of wire vertically upward through a stress relieving mechanism, and then is passed down through a short vertical tube (pen), the bottom end of which is in contact with, or in the vicinity of, the top adhesive surface of the film then, as the tube is dragged sideways, the wire sticks to the film and is dragged through the tube and off the reel.

As the pen is moved through a simple or complex pattern over the film, a trail of wire is left stuck to the adhesive layer of the film, in the same pattern, but with a very small amount of rounding of any sharp corners.

If the pen has a very small opening at the point where it is in contact with the adhesive, then the pattern of wire can relatively accurately reflect the movement of the pen.

If the pen is slightly rounded where it is in contact with the adhesive coated film then, as one wire crosses over another wire, then the pen will ride over the wire without breaking it. That is, an external surface of the pen that is configured to be in contact with, or in the vicinity of, the substrate may have a region that is obliquely angled with respect to the substrate.

The end of the tube, which can be in contact with the adhesive, may be made of PTFE to prevent or reduce it sticking to the adhesive, when the tube may be dragged sideways using a "Pen Plotter"-type mechanism.

The method may be at least partially automated. The drawing of the tube laterally across the surface can be controlled by a computer program, such as a CAD program. Suitable software enables a well-defined pattern of wire to be laid down on the adhesive coated film.

The method is discussed in further detail with regard to the stages of manufacture using multiple pens in parallel as illustrated in Figures 3a to 3f. Figure 3g shows a pattern for making a similar touch screen to that discussed with reference to figures 3a to 3f but using a single pen and a single wire. A slide track 54 runs along a top edge of the touch pad 36. The track 54 defines a linear path for a pen holder bar 50 to deposit wire in a sensing zone 40 of the touch pad 36. The track 54 allows movement of the pen along the horizontal (x) axis. The holder bar 50 is displaceable with respect to the track to allow a small amount of movement along the vertical axis (y). Four pens A, B, C, D are provided by the movable pen holder bar 50, in this example. A static pen holder rack 51 is provided away from the substrate 22 to hold pens while they are not in use.

The pattern follows a first route from a termination zone/area 42 through a transition zone, and then to a sensing zone 40 of the touch pad in order to provide a first array of wire elements x1-x8. The wire elements x1-x8 may be touch elements and may provide sensing/receiving or controlling/transmitting elements in the sensing zone.

In Figure 3a the pen holder 50 is in a first position at a left hand extremity of the sensing zone 40. Pen A has been moved from the static pen holder 51 to its allocated pen holder on a movable bar 50 leaving a trail of fine wire behind it, stuck to the adhesive coated film. Pens B, C and D are still shown in the pen holder rack 51. The pens B, C and D are then moved, one by one, from the pen holder rack 51 to the pen holder bar 50 (not shown in Figure 3a), leaving a trail of wire 16 behind each of them.

The movable pen holder bar 50 then draws all four pens A, B, C, D as one unit, along the surface 22 of the touch pad 36 from left to right in order to lay first, third, fifth and seventh horizontal sensing elements x1 , x3, x5, x7. Once the holder 50 has reached a right hand extremity of the sensing zone 40, the pen holder 50 moves a small amount in the y axis, dragging all four pens A, B, C and D in the vertical direction. The movable pen holder 50 is then drawn back across the surface 22 of the touch pad 36 from right to left in order to lay second, fourth, sixth and eighth horizontal sensing element x2, x4, x6, x8. In practice, the movement of the pen bar 50, first right, then down, then left, may be repeated several times, with a small amount of down movement linking each run, but is only illustrated once in this example.

In Figure 3b, all of the pens A, B, C, D have been simultaneously dragged sideways to the right then downward for a short distance, then back to the left across the adhesive coated film by the moveable bar 50 to define eight horizontal sensing elements x1-x8. After the horizontal sensing elements x1-x8 have been drawn, pen A is returned to the pen holder rack 51 (or static pen holder) leaving a trail of wire behind it. This is later followed by pens B, C and D.

In Figure 3c, all the pens have been returned to the pen holder rack 51 so that each of the sensing elements in the sensing region 40 are connected to the termination terminal zone 42, which is in the vicinity of, in this example adjacent to, the pen holder rack. Cantilevered movable pen plotter bar 50 has now been moved out of the way, away from the touch pad 36.

A corresponding process takes place for the vertical sensing elements as illustrated in Figures 3d to 3f, with a corresponding y-plotting mechanism. Figure 3f shows a finished touch pad 36.

The pattern of wire follows a second route which runs from the termination zone through the sensing zone in order to provide a second array of wire elements y1-y8. The second series of wire elements y1-y8 overlaps the first series of wire elements x1-x8. The first array of wire elements x1-x8 is substantially perpendicular to the second array of wire elements y1-y8. At least a portion of the wire elements comprise an outer coating of insulation (electrically insulating material) preventing direct electrical contact at the crossover points between the first and second series of wires x1-x8, y1-y8.

Figure 3d shows the plotting mechanism manoeuvred into place ready to plot the vertical sensing elements y1-y8. In this configuration an alternative movable pen holder bar 50 can provide a large amount of vertical (y) movement and a relatively small amount of horizontal (x) movement.

Pen A is shown having already been moved from the static pen holder 51 to its allocated pen holder on the movable bar 50, leaving a trail of wire behind it. Dotted lines indicate the route that will be taken by pens C, D and E.

Figure 3e shows 4 individual wire trails left by the 4 pens after all of them have been simultaneously dragged upwards along the vertical (y) axis then sideways to the right, then downwards, along the vertical (y) axis, across the adhesive coated film 22 by the movable bar 50. After which, pen A has been moved to its original static pen holder 51 , leaving a trail or wire behind it. In practice this movement of the pen bar 50, first up, then right, then down, may be repeated several times with a small amount of right movement linking each run, but is only illustrated once in this example.

Movement of pens B, C and D from the movable holder bar 50 to the static pen holder 51 follow.

Figure 3f shows all 4 pens A, B, C and D returned to the original static pen holder 51 after completing both the x and the y plots. The holder bar 50 has now been moved out of the way, away from the touch pad 36.

Four wires are used in this example, leaving four wire traces throughout the touch pad 36, four connected pairs of x wires joined to four connected pairs of y wire. The wire at the periphery of the sensing region and at the termination zone can be cut in order to provide multiple separate wire elements within the sensing zone, resulting in 8 individual x wires, and 8 individual y wires. The region at the periphery of the sensing zone in which the wire can be cut may be referred to as an extended region of wire, that links two wire elements within the sensing region. Such a cut can therefore provide multiple separate wire elements within the sensing zone.

Figure 3g illustrates a touch pad with a stylized representation of wire elements x1-x8, y1- y8 that have been deposited using the device of figure 1 or figure 2 using a single pen to deposit a single wire. The touch pad 36 is in a near-finished form. A wire 16 has been deposited on the touch pad 36 from a start position 38 at a periphery of the touch pad. A number of horizontal (x) sensing elements have been deposited in a sensing zone 40. The same wire has also been used to deposit a number of vertical (y) sensing elements over a first set of sensing elements in the sensing zone 40. The sensing elements x1-x8, y1 -y8 are connected to one another at a terminal zone. In other words, a first set of joining portions between sensing elements is located in a terminal zone on the substrate. After plotting, the sensing elements x1-x8, y1-y8 can be separated from each other by cutting or scoring the wire in the terminal zone. This terminal zone 42 provides the correct wiring layout for connecting a terminal to the touch pad 36. Adjacent pairs of the horizontal (x) sensing elements x1-x8 are also connected to one another at a right hand side periphery of the touch pad 36. That is, a second set of joining portions is located at a periphery 55 of the substrate, outside the sensing zone 40. Similarly, adjacent pairs of the vertical (y) sensing elements y1-y8 are connected to one another at a top periphery of the sensing pad 36 as shown in Figures 3f or Figure 3g. That is, a third set of joining portions is located at a periphery 53 of the substrate, outside the sensing zone 40. The adjacent pairs of horizontal (x) and vertical (y) sensing elements can be separated from one another by cutting or scoring along the first set of joining portions in the terminal zone 42 and the second and third sets of joining portions in the peripheral regions 53, 55.

After plotting the wiring pattern, a thin printed circuit board (PCB) terminal strip can be placed face down on a terminal area (as discussed above with reference to figures 3a and 3g).

Figure 4 shows a printed circuit board (PCB) terminal strip 43. The PCB terminal strip 43 may be made of 100 micron thick FR4 glass fibre with copper cladding, or copper-clad polyimide film. The copper cladding may be pre-tinned. Silver ink traces on a 100 micron thick polyester base may be used instead of copper-clad fibre glass or Kaptan, if heating above 120 degrees Centigrade is not involved in the fabrication process.

The printed circuit board (PCB) terminal strip 43 can be fitted to a wired film in the termination region in order to enable electrical connections to be made with the wire elements.

The PCB termination/terminal strip may be applied before plotting, after plotting but before lamination, or after plotting and lamination.

If the termination strip is to be applied before plotting then the termination PCB may be stuck, face-up, on the adhesive coating before plotting the wires, allowing the wires to run over the PCB. After plotting, and before laminating, these wires can be soldered to the PCB without soldering through any film.

If the termination strip is to be applied after plotting but before lamination, then the edge of the film may be cut off along the bottom edge of the termination zone, isolating all of the wires from each other. The termination strip is then placed, conductive face down, on the wires, making sure that there is an exposed strip of PCB termination strip, about 6mm wide overlapping the edge of the film, and with the conductive traces of the termination strip aligned accurately with the wires in the termination zone. The back of the termination strip then needs to be pressed down firmly, all over, to make sure the termination strip is stuck securely to the wired film. The film can then be laminated. After lamination, the film is turned over so that the conductive traces of the terminal strip are facing upward. The wires of the film can then be soldered, through the film to the terminal strip.

By placing a sheet of double-sided release film over the termination zone before laminating, it is possible to separate the laminated films in the termination zone after lamination, and then insert the termination PCB and reseal the films. The PCB can then be soldered through a single film.

If the termination strip is to be attached to the film after lamination, then first the edge of the film needs to be cut off along the bottom edge of the termination zone, isolating all of the wires from each other. After fixing a strip of double sided adhesive tape to the conductive side of the terminal strip, leaving about a 6mm wide strip of exposed conductors along one edge. The termination strip is then placed, conductive face down, on the wires in the termination zone, making sure that the exposed strip of PCB termination strip, which is about 6mm wide, overlaps the edge of the film, and with the conductive traces of the termination strip are aligned accurately with the wires in the termination zone. The back of the termination strip is then pressed down firmly to make sure the termination strip is stuck securely to the wired film. The film is then turned over so that the conductive traces of the terminal strip are facing upward and the wires of the film are then soldered, through the film and the double sided adhesive tape, to the terminal strip.

One disadvantage of soldering the wires is that the heat used to form the solder joint may slightly deform the supporting film. A setting, conductive ink can be used as an alternative to soldering. This may be particularly advantageous if the wire is not coated by an insulator.

If the wire is insulation coated and the signals passing through the product are AC and not DC, then conductive ink can be used to provide a capacitive coupling termination, through the insulation.

Figure 5 illustrates a cross section of a portion of a touch pad similar to that of Figure 3g. The portion shows generally perpendicular horizontal (x) and vertical (y) sensing elements The horizontal (x) sensing element is shown in contact with the adhesive layer 22, which in turn is disposed on the plastic film 32. The vertical (y) sensing element bridges (runs) over the horizontal (x) sensing element. It will be appreciated that out of plane of the cross section of Figure 5, the vertical (y) sensing element is substantially in contact with the adhesive 34. One or more of the horizontal (x) and vertical (y) sensing elements may be enamel coated, or coated in another insulating material, in order to prevent shorting between the horizontal (x) and vertical (y) sensing elements. The wires would then not short circuit one another due to a layer of insulation coating surrounding them.

The use of the terms "horizontal" and "vertical" herein, or indeed "x" or "y", may refer to sensing elements that are in different series to one another. These terms may, however, be interchangeable. In the previous examples, the x - axis has been plotted first, while the y - axis has been used to over-plot the x - axis. The y - axis could have been plotted first, and the x - axis over-plotted onto it. Such terms may not mean a strict perpendicular/orthogonal relationship between sensing elements. The axes could be plotted at angles such as 30 degrees or 47 degrees to each other instead of 90 degrees. Sixty degrees is often used when three axes are plotted, thereby forming an isometrically wired arrangement. The wires can also be plotted non-linearly, possibly providing substantially curved or zig-zagged sensing elements in the sensing zone.

Figure 6 illustrates the touch pad or screen with zig-zagged sensing elements. The touch pad 44 comprises 8 horizontal (x) sensing elements and 8 vertical (y) sensing elements that are each separated from one another. The touch screen is suitable for multi-touch capacitance sensing in either a "self-capacitance" mode or a "mutual capacitance" mode. All of the sensing elements terminate at a terminal connector 42.

The wires follow a non-linear route (are zig-zagged) in a number of different ways. The non-linear route provides a number of advantages over strictly linear plots:

I) covering a wider surface area than is covered by a single straight run of wire - in this example, x wires are zig-zagged three times to cover three times the area of a single wire;

II) preventing unwanted reflections from external light sources, such as the sun. Wires running in a constant linear direction can create severe unwanted reflections - zigzagging breaks up these reflections, greatly reducing this effect;

III) reducing the number of crossing of x and y wires - in this example, the number of crossings is reduced by a factor of three compared with having just vertical and horizontal wires;

IV) preventing visual interference patterns between the wires and the pixels on the display screen - non-linear patterns and zig-zagging reduces Moire interference patterns; and

V) providing a pattern of wire that is less visually distracting than a grid of straight vertical and horizontal lines.

Advantages II) and V) can also be enhanced by using dark coloured enamel coated wire and/or wire with an anti-reflection coating.

In Figure 6, the x wires have been cut at the right hand side of the touch screen. The y wires have been cut at top side of the touch screen. This creates 8 individual x wires and 8 individual y wires, suitable for a capacitive touch sensing touch-screen.

If the wires were left uncut, so pairs of x wires are permanently joined together, and pairs of y wires are permanently joined together, then an electric current could flow between the pairs of wires if required. Such an arrangement may make the screen suitable for inductance sensing and may enable the current in the wires to heat up the screen.

Figures 7a to 7c illustrate various states in the formation of a "no-soldering" termination zone, in which conductive ink is used, instead of solder to terminate the wires.

In Figure 7a wire 16 is drawn in from the screen region, or sensing zone 40 and deposited in a tight spiral, formation in a termination zone 42. An end of the wire in the termination zone 42 is drawn outside of termination zone into a cutting region 46. The wire is then drawn back in from the cutting region 46 into the termination zone 42 to form another termination in a tight spiral formation. The wire 16 from the second spiral formation is then drawn back into the sensing zone 40. A repetition of this pattern is shown in Figure 7a. Figure 7a shows how wire can be concentrated by plotting the wire in a tight spiral at each potential termination point, thereby providing a good external capacitive or electrical connection. The tight spiral is a means of concentrating wire into a very tight spot. Other patterns could have been used as an alternative, such as tight zig-zagging.

In Figure 7b graphite ink or a silver loaded epoxy has been screen printed, block printed, stencilled or ink-jet printed onto the terminations. The terminations are separated from each other by providing a cut 47. The cut separates the individual terminations from one another by severing the wire 16 that would otherwise provide an electrical connection.

In Figure 7c the terminations on the plastic film 32 have been aligned with tracks on a PCB and placed face to face with each other so that the terminations on the film form an electrical contact with the tracks of the PCB. Figure 7c shows how a PCB terminal strip can be stuck, conductive face down, onto the conductive pads after they have set hard, using 3M 9703 electrically conductive transfer tape, for example. This tape has the ability to stick one electrical conductor to another electrical conductor and form an electrical contact between them. As no heat is used, the PCB terminal strip may be made of polyester with pre-printed silver or graphite conductive strips, instead of fibre glass or Kaptan.

The end product can then be laminated, as previously described.

Figure 8 illustrates a single substrate 22 comprising a number of different structures of different types. The substrate 22 comprises track formations suitable for use as power inductors 50, a near field communication inductor 52, stylus detectors 54 and capacitors 56. Each of the structures 50 - 56 are terminated to a common termination connector 42. The inductors, however, each have two terminations, whereas the capacitors each have only one termination. Suitable patterns for such conductors will be appreciated by those skilled in the art.

Figure 8 shows how capacitors and inductors can be manufactured at the same time on a single film.

Figure 9 illustrates a method 90 for forming a structure with wire elements using a wire depositing device with a tube for laying a wire. The method comprises:

feeding 92 a free end of the wire through the tube of the wire depositing device; and

drawing 94 the tube laterally across an adhesive surface of a substrate in a pattern such that the free end of the wire adheres to the adhesive surface and the lateral movement causes the wire to be drawn through the tube and deposited as a trail in accordance with the pattern drawn by the tube crossing the substrate.

The adhesive surface of the substrate on which the wire is placed may be laminated in order to encapsulate the wire. After lamination, the terminating wire can be soldered, optionally through the plastic film of the substrate or laminate, to make an electrical connection between the wire and a terminal strip. One or more of the substrate, adhesive layer and/or laminate may be transparent or translucent. One or more of the substrate, adhesive layer and/or laminate may be opaque. The substrate or laminate can comprise a film with a thickness less than 500 microns. The substrate or laminate may be rigid or flexible, depending on the intended application. The substrate or laminate may comprise a plastics material. For example, the substrate may be flexible such that it can form a bent or curved shape in which a tangent to a first portion of the substrate is more than 10 degrees from parallel with a second portion of the substrate. Electronic circuitry may be provided in the substrate in some applications.

Although the words vertical (y) and horizontal (x) have been used in this description to describe the arrangement of the sensing elements, other orientations may also be used.

An example of a manufacturing process for small clear multi-touch capacitive touch- screens up to 15 inch diagonal is described below with reference to steps 1 to 12. The process requires consumables and equipment.

The consumables include:

1) A3 sheet of 25 to 100 micron thick adhesive-coated polyester film.

2) Conical ended reel of 10 to 25 microns diameter enamel-coated copper wire.

3) Flexible PCB terminal connector strip, with terminals printed on a 2.54mm pitch.

4) Solder.

5) Polyester laminating film (25 to 100 micron thick).

6) Masking tape and double sided adhesive tape.

The equipment includes:

1) An A3 pen plotter.

2) Modified plotter pen and strain relief mechanism.

3) Personal computer with suitable software.

4) Soldering iron.

5) An A3 laminating machine (optional).

1) The pen plotter is modified as shown in Fig 2a. The inside mechanism of the pen is removed. The tip is removed. A hole left by removing the tip is smoothed on its inner edge, with the tip of a small drill bit, rotating this gently by hand. 2) The wire spool is set up as shown in Figure 1. The spool and strain relief may be fixed to a non-moving part of the plotter, on a separate surface, or on the moving pen mechanism. If placed on the movable pen mechanism, then the spool of wire will move with the pen and along the same route as the pen.

The strain reliever may pull the wire from a position directly above the centre of the spool.

The wire is fed directly up from the spool, through the stress reliever mechanism, into the top of, and through, the pen. The initial threading of the wire may be aided by feeding a relatively stiff piece of wire through the pen from the bottom, as described below.

After inserting the stiff wire through the hole in the pen nib, and pushing it through the pen barrel until it is exposed at the top of the pen, a small amount of quick setting adhesive is applied to the exposed tip of the stiff wire.

The end of the fine wire is wound round the tip of the stiff wire (that has been passed through the pen in the opposite direction to that in which the fine wire will be dispensed during manufacture of the touch pad) one or more times, and the adhesive is allowed to set, thereby sticking the fine wire to the tip of the stiff wire.

Once stuck, the stiff wire is pulled back out through the pen together with the fine wire. The fine wire is then detached from the thick wire.

The pen is then placed in the pen holder at the starter position, and a free end of the fine wire is temporarily held to the edge of the plotter table (body) by a strip of double sided tape. This strip of double sided tape should be stuck to the plotter table in such a position as the pen will run over it as it starts and finishes its plot. It is important that the wire is held securely to the plotter table before plotting has begun, otherwise, at the commencement of plotting, as the pen moves, the wire will be pulled out of the pen.

3) After connecting the plotter to a computer and loading appropriate software, the A3 sized film is placed, adhesive side up, on the bed of the plotter, and the protective overlay film is removed.

The film may be held on the bed with small pieces of masking tape on the corners, and along the edges, by means of clamps or by means of an electrostatic bed or vacuum bed. A piece of masking tape may be used as a step in the zone where the wire will eventually run onto the film, to prevent the film lifting as the pen runs onto it.

4) The plotter program is then started and allowed to complete the plot, after which the pen will run over the double sided tape, and be returned automatically to the starting position. The wire will stick to the double sided tape as it runs over it, at the end of the plot.

5) The wire is then cut at a point between the edge of the film where it exited the plotting surface, and the adhesive tape, such that the free end coming from the pen is left attached to the strip of double sided adhesive tape.

6) The next stage may vary, depending on the method used to terminate the wires to the flexible printed circuit board. For example, the wire may be terminated by:

i) Cutting off the bottom edge of the film at a suitable position to separate the wires in the connector region.

ii) Placing the connector strip, conductor side face down, aligning the connector strip over the wires in the terminal area, with the wires running centrally down and parallel with the conductor zones and leaving an exposed length of terminal strip about 6 mm wide sticking out from the edge of the film.

The PCB is then firmly pressed down over all of its back surface to ensure a good adhesive contact is formed between the wire and the adhesive film.

7) The A3 sheet with its plotted wire pattern and PCB terminal in place may be heat laminated by a laminating machine, dry pressure roll laminated or wet laminated to another sheet of plain polyester (if 10 micron diameter wire is used) or adhesive coated polyester (if 25 micron wire is used). If the sheet is wet laminated, then the film may have to be left for a day or so to dry before further processing is performed.

8) The film is then turned over so that the conductors in the terminal strip PCB are facing upwards and the wire is then soldered through the polyester film to the terminal strip, avoiding soldering too close to the edge of the PCB. The soldering may be done with a soldering iron or a hot bar, for example. The hot bar may solder all the wires in one go in about 5 seconds. 9) Wires may be tested for continuity between adjacent connection strips. Lack of continuity can indicate that the soldering was not completed properly and needs to be repeated.

10) Any shorting wire links between terminal conductors may then be cut with a scalpel through the film.

11 ) Pairs of horizontal (x) and pairs of vertical (y) wires are also separated, either by cutting through the film with a scalpel or guillotining off the edges.

12) After trimming off the edges, the touch-screen is now complete and ready for further testing.

It can take some significant time to manufacture a very large product using a single pen plotter. For example, 15 inch diagonal touch-screen may take 4 minutes to plot, whereas a 100 inch touch-screen may take up to eight hours.

Since, however, the plotting method eliminates many of the steps that are necessary for the manufacture of similar products by other means. This manufacturing time may be considered an acceptable trade-off for the benefits of the plotting method. This is especially the case when equivalent machinery, for manufacturing by other methods, could cost millions of pounds and be more restricted in what it can manufacture in terms of size and customisation capability.

There are, however, several ways of speeding up the pen plotting process:

1) Duplicate the whole system.

Since the pen plotting machinery is very inexpensive, it does not cost much to have a large number of plotter mechanisms operating in parallel or, if all the products are identical, drive a large number of pens from one common plotter mechanism. Parallel processing does not speed up the time it takes to make an individual product, but does significantly reduce the time it takes to produce a large number of identical products. For example, it may take 4 minutes to make one screen, but by making ten screens at once, each screen effectively only takes 24 seconds to make.

2) Use more than one pen at a time.

If it is important to be able to speed up the time it takes to make one individual product, then more than one wiring pen can be used on a plotter mechanism at the same time. A 3 metre touch-screen, may take up to eight hours to make, but the majority of the time is taken up plotting the "sensing zone". The sensing zone may be relatively simple and repetitive, and can be manufactured much quicker if a group of pens attached to a common drive bar are used for plotting the sensing zone.

Plotting the regions outside the sensing zone, such as tbe-transition and termination zones, is more difficult because wires come very close together, possibly within a fraction of a millimetre of each other, but the pens may be several millimetres wide. This problem can be overcome, however, by moving just one pen at a time through these zones. All of the pens may be moved together at the same time through the sensing zone. A simple x - y plotter mechanism can be used for moving the pens through the termination and transition zones, and a common pen holder bar can be used to move all the pens at the same time through the sensing zone.

A simple way to make this product much faster therefore would be:

1) Use a simple plotter mechanism to drive one pen through the termination zone, and then through the transition zone to a common drive bar. The pen is then attached to the common drive bar. This process is then repeated for the other pens until all of them are attached to the common drive bar. When all the pens are in position, the drive bar takes all the pens together as one, across the sensing zone and back again. This process may be repeated several times. Each time the drive bar slightly offsets the position of the pens. After the required number of passes the pens are collected, one after the other, from the drive bar, taken through the transition zone and the terminal area and deposited back at the finishing position.

2) The whole process is repeated again for the orthogonal direction by effectively rotating the drive bar through 90 degrees relative to the substrate and moving it to an appropriate position to start plotting the "sensing zone" in that direction.

For this second plot, the same (or different sets of) pens are collected, one at a time from their resting position, moved through the terminal zone, along their designated edge tracks, to the correct position on the Drive Bar.

Here they are again attached to the Drive Bar. Once the Drive bar has plotted all the wires in the y direction, it returns to its original position, slightly offset, where the pens are collected again, one by one, returned through their appropriate edge routes, through the terminal area, and back to their finishing position.

It will be appreciated that a technical difficulty may occur when a standard x - y mechanism is used to move several pens around the plotter bed. Pens and wire may have been placed in the way of the x or y drive track. This can be a severe problem if the wire spools are fixed to the side of the plotter, potentially leaving trails of wire in inconvenient places. The solution to this is to have the pens and spools move together all the time, and have the x or y drive tracks sufficiently high above the plotting table so that they pass over the pens and spools without crashing into them.

Alternatively a robot arm can be used.

This process could speed up manufacture of a 3 metre (100 inch) touch-screen from eight hours to about half an hour, or less.

Instead of plastic, the sensor could be made using paper. For example, sticky paper may be used for receiving the plotted the wires instead of sticky plastic.

Due to the fact that the final product can be made very thin and flexible, the substrate can be made of plastic or paper, and can even be creased without loss of functionality, the product can not only be curved but, Origami-type techniques may be used on it with cutting, folding and use of glue to produce very complex shaped sensors. One film, or paper sheet, with wire embedded in it, may have two discrete sensing zones, representing two separate touch interactive pages, and, like pages of a book, the two sensing zones could be joined together through a creased spine without loss of functionality. Thin flexible films could be inserted into injection moulds to make three dimensional touch products which are touch interactive on one or more or all of their surfaces, edges and even corners.

If PVC, or another heat sensitive film is used in the manufacturing process instead of polyester, then the end product may be heat/vacuum formed into even more intricate shapes and still retain its sensing capability. The wires may alter their position during vacuum forming and may even stretch and break. Plotting the wires in a zig-zagged trace, however, can prevent, or reduce, the likelihood of the wires breaking during stretching, especially at points of excessive stretching. As the film stretches, the zig-zagged wires will straighten out, and so are not themselves stretched. This prevents the possibility of the wires breaking. The wires can even move laterally sideways during vacuum forming without damage.

A zig-zagged pattern is a line with a plurality of bends in it that may produce a repeated pattern. The bends can be abrupt (angular) or a smooth curve. The zig-zagged wires typically straighten out during vacuum forming, instead of stretching. This alternative motion provides stress relief and so can prevent, or reduce the likelihood of them breaking.

If it is important to have a very well defined position for the wires in the final vacuum formed product, the product can be pre-formed, without wire in it. The desired positions of the wires can then be drawn on the formed shape. The product can then be re-heated, and allowed to relax into its original flat form. The new layout of the wires shows how the wires need to be laid out in order to be in the correct positions after vacuum forming.

Instead of plotting one sheet at a time, plotting may be employed on a "roll to roll" basis. Instead of starting and finishing the plotting at the same point, each plot could finish one screen's width further on. This would allow another screen to be plotted next to the first. The next screen may be identical to/or different from the first screen.

The process can be repeated until a roll of screens have been plotted. The roll can then be laminated, cut-up and have terminations fitted. Alternatively, the plot could start and finish at the same point, but the roll of film could be moved on, a plot width at a time, continuously presenting a fresh sheet for plotting the next product as soon as the previous one is completed.

There are many variables that can be changed when using the plotting technique, for example:

1) wires may come to more than one terminal or more than one wire may come to a single terminal; non-insulated wire may be used. The wires may be plotted onto two separate surfaces, then laminated together with a third insulating sheet between them;

3) a clear insulating film of ink may be printed at the potential cross-over points on a first series of wires. Once the ink has dried a second series of wires can be over-plotted - Alternatively, a clear plastic disc could be stamped onto the cross-over point.

4) instead of a simple insulating film of ink, some active sensing or responding material may be printed at potential cross-over points of wires;

5) the end product may have haptic and/or display or light or pressure sensing properties: electroluminescent material such as zinc sulphide doped with copper (which produces a green light), or zinc sulphide doped with silver (which produces a blue light) may be used. Piezo-electric crystals may be deposited at the junctions between the x and y wires. The crystals are configured to vibrate when an alternating current (AC) is applied between the appropriate x and y wire, creating a tingling (haptic) feeling to the touch. Alternatively, the piezo-electric crystal can be used to produce a voltage when a physical pressure is applied to it;

6) electronic circuitry may be embedded into the film;

7) the wires may be made of alternative materials to copper or silver, such as tungsten or Nichrome. Different wires or series of wires may be made of the same material or different materials; and

8) some of the wires may be insulated and some may not be insulated;

9) some of the wires may be terminated at the edges and some may not be terminated at the edges.

10) clear film may be replaced in many applications by opaque film.

1 1) thin film may be replaced by thick film, or even rigid sheets, in some applications.

12) Non-insulated wires may be joined to other non-insulated wires by the application of a blob of conductive ink where the wires are in very close proximity, causing an electrical connection between them. It will be appreciated that the orientations described herein are often relative so, the terms "up" and "down" may be replaced by "down" and "up" in some case, excluding the cases where the effects of gravity are inherent to the working of the system. Similar considerations apply to the terms, "top", "bottom", "left" and "right".

Claims

1. A method for forming a structure with wire elements using a wire depositing device with a tube for laying a wire, the method comprising:

threading a free end of the wire through the tube of the wire depositing device; and drawing the tube laterally across an adhesive surface of a substrate in a pattern such that the free end of the wire adheres to the adhesive surface and the lateral movement causes the wire to be drawn through the tube and deposited as a trail in accordance with the pattern drawn by the tube crossing the substrate.

2. The method of claim 1 wherein the depositing device comprises a pen plotter-type apparatus.

3. The method of claim 1 or claim 2, wherein the structure is a touch pad, and wherein the pattern follows a first route from a termination zone, then through a transition zone, then through a sensing zone of the touch pad in order to provide a first array of wire elements.

4. The method of claim 1 or claim 2, wherein the structure is a touch pad, and wherein the pattern follows a first route from a termination zone, then through a transition zone, then through a sensing zone of the touch pad, before returning, via a transition zone, to the termination zone, whereupon this process may be repeated several times, providing a first array of wire elements using a single wire.

5. The method of claim 3 or 4 wherein the pattern follows a second route which runs from the same, or an alternative termination zone, through the same, or an alternative transition zone, then through the sensing zone in order to provide a second array of wire elements.

6. The method of claim 3, claim 4 or claim 5 wherein the pattern follows a third route which runs from the same, or an alternative termination zone, through the same, or an alternative transition zone, then through the sensing zone in order to provide a third array of wire elements.

7. The method of claim 5 wherein the first array of wire elements is transverse to the second array of wire elements, and wherein the second array of wire elements may overlap the first array of wire elements.

8. The method of claim 5 or 6 wherein all the arrays of wire elements are transverse to each other, where all the arrays of wire elements may overlap each other.

9. The method of claim 7 or claim 8 wherein at least a portion of the wire comprises an outer coating of insulation configured to prevent direct electrical contact at the crossover points between the first and second arrays of wires.

10. The method of any preceding claim comprising providing, at a periphery of the sensing zone, an extended region of wire linking two wire elements within the sensing region. . The method of claim 0 comprising cutting the wire in the extended region in order to provide multiple separate wire elements within the sensing zone.

12. The method of any preceding claim comprising fitting a terminal connector to a termination zone, in order to enable electrical connections to be made with the wire elements in the sensing zone.

13. The method of any preceding claim comprising laminating the adhesive surface in order to encapsulate the wire elements.

1 . The method of any preceding claim wherein the substrate, adhesive layer and/or laminate are transparent or translucent.

15. The method of any preceding claim wherein the tube has a nib, the method comprising providing the nib in contact with the adhesive during the drawing step.

16. The method of any preceding claim wherein the substrate comprises a film with a thickness less than 1000 microns.

17. The method of any of claims 1 to 15 wherein the substrate comprises a plastics material, cloth fabric, leather, paper, glass or ceramic.

18. The method of any preceding claim wherein the substrate is flexible such that the substrate can form a bent or curved shape in which a tangent to a first portion of the substrate is more than 10 degrees from parallel with a second portion of the substrate.

19. The method of any preceding claim wherein the method is at least partially automated and the drawing of the tube laterally across the surface is controlled by a computer program.

20. The method of any preceding claim comprising providing electronic circuitry on the substrate.

21. The method of any preceding claim comprising using a plurality of wire depositing devices in parallel to form one or more touch-sensors with wire elements.

22. A wire depositing device or a computer program configured to perform the method of any of claims 1 to 21.

23. A wire depositing device comprising:

a hollow tube for receiving a wire;

a nib attached to the hollow tube and configured to lay the wire on an adhesive surface of a substrate;

a holder for holding the tube; and

24. A method of manufacturing a wire depositing device comprising:

receiving a pen plotter device comprising a pen, and a holder coupled to a driving mechanism;

removing an internal drawing mechanism of the pen to provide a hollow tube; and feeding wire through the hollow tube of the pen.

25. The method of claim 24 further comprising adapting a nib of the pen to allow a wire to be passed through the nib.

26. A method for creating a very thin "wire-based" flexible multi-touch "self capacitive" and "mutual capacitive" touch-screen using a thin clear adhesive coated plastic film whereupon a modified plotter type pen with one strand of fine insulation coated wire running through it, is drawn sideways across the adhesive coating of the film by a plotter type mechanism, in a pattern, determined by a suitable CAD program, whereby, the effect of the wire sticking to the adhesive coating, and the sideways movement of the pen causes the wire to be drawn through the pen and permanently deposited as a trail showing the pattern of movement of the pen across the film, this trail following a first route which runs from the pen's starting position, through a termination zone along a transition route outside the "sensing zone", and then mainly runs through the "sensing zone" along one axis, leaving a trail of wire representing an x array of touch sensing/receiving or controlling/transmitting elements, returning periodically to the termination zone, whereupon, on completion of the x array, the trail then follows a second route which runs from a termination zone along the same, or an alternative transition route outside the "sensing zone", and then mainly runs through the "sensing zone" along an axis which is at right angles to, and runs over, the wire already laid down in the "sensing zone" along the first axis, the overlying wire representing a y array of touch sensing/receiving or controlling/transmitting elements, the insulation preventing direct electrical contact at the cross-over points where the y array parts of the wire run over the x array parts of the wire, whereupon, after periodic returns to the termination zone, and completion of the y array pattern the pen is returned to its finishing position, which may or may not be the same as its starting position, whereupon, either at this time, or later in the process of manufacture, various positions along the wire are cut resulting in multiple isolated touch sensing/receiving or controlling/transmitting wires running from the termination zone to the x and y axes of the "sensing zone", the process of manufacture being completed by the fitting of a terminal connector and the lamination of the adhesive coated film to another thin clear plastic film with subsequent final trimming.

27. A method for creating a very thin "wire-based" flexible multi-functional inductive sensing/transmitting screen using a thin clear adhesive coated plastic film whereupon a modified plotter type pen with one strand of fine insulation coated wire running through it, is drawn sideways across the adhesive coating of the film by a plotter type mechanism, in a pattern, determined by a suitable CAD program, whereby, the effect of the wire sticking to the adhesive coating, and the sideways movement of the pen causes the wire to be drawn through the pen and permanently deposited as a trail showing the pattern of movement of the pen across the film, this trail following a first route which runs from the starting position of the pen, through a termination zone along a transition route outside the "sensing/transmitting zone", and then runs into the "sensing/transmitting" zone in a pattern determined by the required functionality of the inductive structure, whereby a simple metal or stylus detector might have a simple loop, a near field communication structure might have a simple coil with a few turns in it, and a power transmission or reception structure might have a coil with multiple turns in it, wherein, after this structure has been traced, the pen returns to the termination zone, the process of tracking from the terminal zone, to the sensing/transmitting zone, and returning to the termination zone being repeated a number of times, depending on the number of different inductive structures required, thereafter, the pen returning to its finishing position, whereupon, either at this time or later in the manufacturing process, wires are cut, in the termination zone, resulting in each inductive structure having its own discrete length of wire, both ends of which end at the termination zone, the process of manufacture being completed by the fitting of a terminal connector and the lamination of the adhesive coated film to another thin clear plastic film, with subsequent final trimming.

28. A method for creating a touch-screen using a thin clear adhesive coated plastic film whereupon a modified plotter type pen with one strand of fine wire running through it, is drawn sideways across the adhesive coating of the film by a plotter type mechanism, in a pattern, determined by a suitable CAD program, whereby, the effect of the wire sticking to the adhesive coating, and the sideways movement of the pen causes the wire to be drawn through the pen and permanently deposited as a trail showing the pattern of movement of the pen across the film, the process of manufacture being completed by the cutting of the wire into separate discrete sections, if required, the fitting of a terminal connector and the lamination of the adhesive coated film to another thin clear plastic film.

29. A method for creating a very thin "wire-based" flexible multi-touch "self capacitive" and "mutual capacitive" touch-screen using a thin clear adhesive coated plastic film whereupon a number of modified plotter type pens, each with one strand of fine insulation coated wire running through it, is drawn sideways across the adhesive coating of the film by a plotter type mechanism, one after another, in a pattern determined by a suitable CAD program, whereby, the effect of the wire sticking to the adhesive coating, and the sideways movement of the pen causes the wire to be drawn through the pens and permanently deposited as a trail showing the pattern of movement of the pens across the film, this trail following a route which runs from each pen's starting position, through a termination zone, then along a transition route outside the "sensing zone", whereupon each pen is fixed, one after another to a single movable bar, this bar then carrying these pens through the "sensing zone" mainly along one axis, leaving a trail of wire representing an x array of touch sensing/receiving or controlling/transmitting elements, the bar finally returning to its original position but slightly offset in the y axis, wherein each pen is then individually moved, one after the other, back, through the transition zone and the termination zone, to its finishing position.

30. The method of claim 29 wherein the same method is used for the y - axis.

31. The method of claim 29 wherein the x axis is over plotted by the method used in claim 30.

32. The method of claim 31 wherein a different set of pens is used to plot the y axis.

33. The method of any of claims 1 to 21 or 26 to 32 wherein the wire is enamel coated copper.

34. The method of any of claims 1 to 21 or 26 to 32 wherein the wire is tungsten.

35. The method of any claims 1 to 21 or 26 to 33 wherein the wire has a diameter range from 5 microns to 50 microns.

36. The method of claim 35 wherein the wire has a diameter of 3 microns to 25 microns.

37. A "no soldering" Capacitive method for terminating enamel coated wires, whereby the wires are first plotted on adhesive coated plastic or paper, in a very tight pattern at the termination point, this pattern then being overprinted with conductive ink, using a stencil, screen printing, or ink-jet printing, a connector terminal then being placed over, and in direct electrical contact with the conductive ink, creating capacitive coupling between the wire and the connector terminal, but no direct electrical contact between the wire and the connector terminal.

38. A "no soldering" method for terminating bare wires, whereby the wires are first plotted on adhesive coated plastic or paper, in a tight pattern at the termination point, this pattern then being overprinted with conductive ink, using a stencil, screen printing, or ink- jet printing, a connector terminal then being placed over, and in direct electrical contact with the conductive ink.

39. A method of terminating wires laid down on adhesive coated film as described in any of claims 3 to 8, or 26 to 32, whereby, a pcb terminal strip is placed on the adhesive film before the wire is plotted, the pcb having conductors facing upward, in such a position whereby, as the wire(s) are plotted they run over the pcb in the places where the conductive traces are found, whereby, after the plotting is completed, these wires are directly soldered to these conductive traces.

40. A method of terminating wires laid down on adhesive coated film as described in any of claims 3 to 8, or 26 to 32, whereby, a pcb terminal strip is placed on the adhesive film after the wire is plotted, the pcb having conductors facing downward, in such a position whereby, the plotted wire(s) run under the pcb in the places where the conductive traces are found, whereby, these wires are soldered through the film to these conductive traces.

41. A method of terminating wires laid down on adhesive coated film as described in any of claims 3 to 8 or 26 to 32, whereby, after the wire(s) have been laid down, a strip of double sided release paper is temporarily attached to the adhesive film, covering the termination zone, the film then being laminated to another film, after which, the position where the release film was embedded is delaminated and the release paper removed, allowing the pcb terminal strip to be placed, conductive traces facing downward, in such a position whereby, the plotted wire(s) run under the pcb in the places where the conductive traces are found, thereby enabling these wires to be soldered through the film to these conductive traces.

42. A method of terminating wires laid down on adhesive coated film as described in any of claims 3 to 8, or 26 to 32, whereby, after the film has been laminated to another film, a pcb terminal strip is stuck to the film with conductive traces facing downward, using double-sided adhesive tape, in the terminal area, with the pcb conductive traces aligned with the wire(s) in the terminal area, the wires then being soldered to the pcb terminal strip, through the two layers of plastic film.

43. A method of producing wire embedded touch screens on a roll to roll basis, using the manufacturing methods described in the previous claims, wherein, the adhesive coated film is automatically moved to a new position after each plot is completed, the amount of movement equal to, or greater than the width of the touch-screen being manufactured, the process of plotting a new identical, or different touch screen then beginning again, this whole process repeating until sufficient touch screens have been produced, or until the end of the roll of film.

44. The method of claim 43 wherein immediately after plotting, the newly plotted part of the film is covered with release paper and rolled onto a new roll until the roll has been completely plotted, or until enough touch screens have been manufactured, thereafter the roll is being sent through a termination fixing, lamination and touch screen separation process.

45. The method of any of claims 3 to 8 or 26 to 32 wherein the x and/or the y wires are plotted in loops, outside the sensing area, thereby enabling them to be cut at a later stage, either by scoring the wire with a cutting instrument, or by cutting off the edges of the film which contain the ends of the loops.

46. The method of any of claims 3 to 8, 20 or 26 to 28 wherein a number of identical touch screens can be manufactured at the same time by connecting a number of pens to the same x - y plotting mechanism, each pen spaced apart from its neighbour so that plots do not overlap.

47. The method of any of claims 3 to 8 or 26 to 32 wherein the wire is laid down in a non-linear or zig-zagged manner in the "Sensing/Visual" zone.

48. The method of any of claims 3 to 8 or 26 to 32 wherein the adhesive coated film is heat sensitive, enabling the product to be heat/vacuum formed into complex shapes.

49. The method of claim 48 wherein where the wires are laid down in a non-linear or zig-zagged manner in areas that will be distorted by heat forming, enabling the wires to straighten out or move, without breaking, while heat forming is taking place.

50. The method of claims 3 to 8, 29 or 30 wherein where two separate films are used, one for the x - axis and another for the y - axis, whereby one of the films is laminated, face up, to the other film, which is face down, one set of wires, at least having an insulating coating.

51 The method of claims 3 to 8, 29 or 30 wherein three separate films are used, one for the x - axis, another for the y - axis, and a third, intermediate insulating film, whereby one of the films is laminated, face up, to the intermediate insulating film, and the other film is laminated, face down onto the insulating film, whereby, none of the wires need to have insulation coating.

52. The method of claims 3 to 8, 29 or 30 wherein the adhesive coated film, with wire already attached, is attached to a second active surface, which does not use wire as the sensing, controlling or transmitting element.

53. The method of claim 52 wherein where the "non- wire" material is conductive, reticulated printed material.

54. The method of claim 52 wherein the "non- wire" material is Indium Tin Oxide.

55. The method of claim 5, 8, 26 or 31 wherein an insulating disc may be inserted at the potential cross-over points between the x and y axes, after one axis has been plotted and before the second axis is plotted.

56. The method of claim 5, 8, 26 or 31 where an electro-luminescent material may be inserted at the potential cross-over point between the x and y axes, after one axis has been plotted and before the second axis is plotted.

57. The method of claim 5, 8, 25 or 31 where a haptic material may be inserted at the potential cross-over point between the x and y axes, after one axis has been plotted and before the second axis is plotted.

58. The method of claim 3 to 8, 26 or 31 wherein the sensing zones may be broken up into several discrete, evenly spaced, or irregularly spaced sensing zones, the wires coming together at a common terminal or to separate terminals.

59. The method of claim 33 wherein the enamel coating is dyed a dark colour and/or has low reflectivity.

60. The method of any of claims 6, 26, 27 or 30 to 32 wherein more than two axes are plotted.

61. The method of claim 60 wherein more than three axes are plotted.

62. The method of claim 60 wherein two or more non-insulated wires plotted on the adhesive film, may be electrically joined, if they come within very close proximity to each other, by applying a spot of conductive ink to the conjunction of the two wires, the ink being applied by any one of various means, such as screen printing, ink jet printing, block printing, or stencilling.

63. A method substantially as described herein with reference to the accompanying drawings.

64. An apparatus substantially as described herein with reference to the accompanying drawings.