The present invention relates to a frame for a touch-sensitive device and film application tool therefor.

Touch-sensitive systems ("touch systems") are in widespread use in a variety of applications. Typically, the touch systems are configured to detect a touching object such as a finger or stylus, either in direct contact, or through proximity (i.e. without contact), with a touch surface. Touch systems may be used as touch pads in laptop computers, equipment control panels, and as overlays on displays e.g. hand held devices, such as mobile telephones. A touch panel that is overlaid on or integrated in a display is also denoted a "touch screen". Many other applications are known in the art.

There are numerous known techniques for providing touch sensitivity, e.g. by incorporating resistive wire grids, capacitive sensors, strain gauges, etc. into a touch panel. There are also various types of optical touch systems, which e.g. detect attenuation of emitted light by touch objects on or proximal to a touch surface.

A known touch-sensitive apparatus is an‘above surface optical touch system’, with a set of optical emitters are arranged around the periphery of a touch surface to emit light that travels above the touch surface. A set of light detectors are also arranged around the periphery of the touch surface to receive light from the set of emitters from above the touch surface. An object that touches the touch surface will attenuate the light on one or more propagation paths of the light and cause a change in the light received by one or more of the detectors. The location (coordinates), shape or area of the object may be determined by analysing the received light at the detectors. Examples of such touch systems are found in e.g. PCT/SE2017/051233 and PCT/EP2018/052757.

One component of the touch-sensitive device is a diffuser for propagating the light over the touch surface correctly. The diffuser can be an elongate piece of plastic with a surface having light diffusive properties angled to diffuse the emitted light over the touch surface. The diffuser is clipped or glued into the frame of the touch-sensitive device.

A problem with the diffuser component is that it is relatively expensive to manufacture and install. Furthermore, the diffuser must be located above the touch surface to guide and diffuse the light above the touch surface. This means that the size of the diffuser affects the size of the bezel at the end of the touch- sensitive apparatus.

Embodiments of the present invention aim to address the aforementioned problems.

According to an aspect of the present invention there is a film application tool for an elongate frame of touch-sensitive device wherein the elongate frame comprises a diffusion surface arranged to receive a light diffusing film, the film application tool comprising: an applicator carriage moveably mountable on the elongate frame; an application surface engageable with the diffusion surface of the elongate frame: andat least one reference surface for aligning the light diffusing film with respect to the applicator surface; wherein when the applicator carriage moves with respect to the frame, the application surface urges the light diffusing film towards the diffusion surface.

This means that the film application tool can accurately laminate the elongate frame with the light diffusing film. This improves the speed and accuracy of the manufacturing process.

Optionally, the at least one reference surface is the application surface. Optionally, the at least one reference surface is a film channel for receiving the light diffusing film, the film channel intersects with the application surface and is arranged to feed the light diffusing film on to the application surface. By providing a reference surface, the light diffusing film is laminated in a straight line in the correct position on the elongate frame. Optionally, a smoothing arm is arranged to engage the light diffusing film on the diffusion surface after the application surface has engaged the light diffusing film. Optionally, the smoothing arm comprises a cushion arranged to engage the light diffusing film. Optionally, the cushion is mounted at an angle to the application surface. In this way, the film is smoothed on the diffusing surface. This removes any bubbles under the film and improves the fix of the lamination of the light diffusing film.

Optionally, the applicator carriage is moveable along the longitudinal axis of the elongate frame. Optionally, the applicator carriage has at least one coupling to prevent relative movement of the film application tool in a plane perpendicular to the longitudinal axis of the elongate frame. Optionally, the at least one coupling comprises at least one overlapping portion to engage an exterior surface of the elongate frame. Optionally, the at least one coupling comprises an interior coupling portion having a reciprocal shape to a cross-sectional shape of the elongate frame. This means that the film application tool prevents the reference surface moving with respect to the elongate frame when the film application tool moves along the elongate frame.

Optionally, the film application tool comprises a finger grip for pulling the tool along the elongate frame.

Optionally, the application surface is angled with respect to a top wall and a side wall of the elongate frame when the film application tool is mounted on the elongate frame.

Optionally, the film channel comprises a first channel and a second channel wherein a feeding path of the light diffusive film reverses direction between the first and second channels. Optionally, a curved connection portion is located between the first channel and the second channel and the radius of curvature of the curved connection portion is above a film creasing threshold radius.

Optionally, the film application tool comprises a separator arranged to separate a backing liner from the light diffusing film. Optionally, the separator is located between the film channel and the application surface, located in the film channel or located upstream of the film channel. Optionally, the separator is a hook to selectively grip the light diffusive film or the backing liner. Optionally, the separator is a lip of an opening wherein the backing liner is arranged to fold over the lip. This means that the backing liner is efficiently removed before lamination and does not snag in the film application tool.

In a second aspect of the invention, there is provided an elongate frame for a touch-sensitive device comprising: a bottom wall, a top wall and a side wall connected therebetween ;a first mounting and a second mounting for respectively fixing at least one light emitter and a touch surface with respect to the frame; and a diffusion surface being integral to the frame and positioned above the second mounting and the first mounting, wherein the diffusion surface is angled with respect to the side wall and the top wall such that light emitted from the emitter is diffused above the touch surface and the diffusion surface is arranged to receive a light diffusing film.

In a third aspect of the invention, there is provided a touch-sensitive device comprises a touch surface; at least one light emitter; and a frame according to the second aspect.

Various other aspects and further embodiments are also described in the following detailed description and in the attached claims with reference to the accompanying drawings, in which:

Figure 1 shows a perspective view of an embodiment of the film application tool;

Figure 2 shows a cross-sectional front view of an embodiment of the film application tool mounted on an elongate frame of a touch-sensitive device; Figure 3 shows a cross-sectional side view of an embodiment of the touch- sensitive device including the elongate frame;

Figure 4 shows a cross-sectional side view of an embodiment of the film application tool whilst mounted on an elongate frame; Figure 5 shows a perspective view of an embodiment of the film application tool;

Figure 6 shows a cross-sectional front view of an embodiment of the film application tool mounted on an elongate frame of a touch-sensitive device; Figure 7a and 7b show a cross-sectional side view of an embodiment of the touch-sensitive device including the elongate frame;

Figure 8 shows a cross-sectional side view of an embodiment of the film application tool mounted on an elongate frame; and

Figure 9 shows a cross-sectional side view of an embodiment of the film application tool mounted on an elongate frame.

Figure 1 shows a perspective view of a film application tool 100. The film application 100 is moveably mountable on an elongate frame 300 (as shown in Figure 3).

The elongate frame 300 is best described in reference to Figure 3. Figure 3 shows a cross sectional side view of the touch-sensitive device 328 comprising an elongate frame 300. The elongate frame 300 extends around the periphery of the touch-sensitive device 328. The elongate frame 300 extends along a longitudinal axis A-A (which extends into the page as shown in Figure 3). The elongate frame 300 comprises a top wall 312, a bottom wall 314 and a side wall 316 connected therebetween. The elongate frame 300 can comprises a plurality of surfaces defining voids for securing internal components. Indeed, the elongate frame 300 can comprise any suitable cross-sectional shape to accommodate different components and geometries. For example, the top wall, comprises multiple exterior surfaces 324, 326. Each of the top wall 312, the side wall 316 and the bottom wall 314 and comprise multiple interior and exterior surfaces.

Figure 3 shows a cross-sectional view through part of the periphery of the touch-sensitive device 328. For the purposes of clarity, not all the components and structure of the touch-sensitive device 328 are shown. A light emitter component 302 is mounted on a substrate 304 such as a printed circuit board (PCB). For the purposes of clarity, a reciprocal light detector is not shown. However, the reciprocal light detector component is mounted on the substrate 304 adjacent to the light emitter component 302. As mentioned previously, the light emitter and light detector components are arranged on the substrate 304 along the periphery of the touch-sensitive device.

The substrate 304 is secured to the frame 300 by a first mounting 306. In some embodiments, the first mounting comprises a pair of slots, each for receiving an edge of the substrate 304. In this way, the substrate 304 is slid in the pair of slots 306 and the substrate 304 is held in place by the slots 306. In other embodiments, the first mounting 306 can be screws, glue, or any other suitable fixture for securing the substrate 304 to the frame 300. The substrate 304 is mounted in the frame so that it extends in a plane which is substantially parallel to a touch surface 308. In this way, if the touch surface 308 extends in a horizontal plane, so does the substrate 304. In alternative embodiments, (for example as shown in Figures 7a and 7b), the substrate 304 can extend in a plane which is substantially perpendicular to the plane of the touch surface 308.

The touch surface 308 is mounted above the substrate 304 in a second mounting 310 in the frame 300. The second mounting 310 is a peripheral slot for receiving an edge 322 of the touch surface 308. The second mounting 310 extends around the entire peripheral edge 322 of the touch surface 308. Both the first and second mountings 306, 310 are integral with the frame 300. In this way, the frame 300 can be extruded using a die comprising the cross-sectional shape of the first and second mountings 306, 310.

A diffusing surface 318 is located in the top wall 312 of the frame 300. In some embodiments, the diffusing surface 318 is integral to the frame 300. In other embodiments, the diffusing surface 318 can be a separate component (not shown). Advantageously, by providing an integral diffusing surface 318 which is part of the frame 300, the height H that the bezel of the touch-sensitive device protrudes above the touch surface 308 is reduced. This is because a bulky, separate diffusion component does not need to be secured to the frame. The diffusing surface 318 is aligned with the light emitter 302 for receiving and diffusing light over the touch surface 308. In this way, light emitted from the light emitter component 302 is incident on the diffusing surface 318. In order to promote the effective diffusion of light over the touch surface 308, the diffusing surface 318 is angled with respect to a plane B-B of the touch surface 308. In some embodiments, the angle C of the diffusing surface 318 is between 40 - 60 degrees with respect to the plane B-B of the touch surface 308. In some embodiments, the angle C is 45 degrees. In other embodiments, the angle C can be varied depending on the diffusion properties (e.g. geometry, material, surface pattern) of the surface of the diffusing surface 318. The diffusing surface 318 further comprises a light diffusing material 320. The light diffusing material 320 comprises a light diffusing surface which diffuses the incident emitted light across the touch surface 308.

In some embodiments, the light diffusing material 320 is a flexible elongate strip of light diffusing material. In some embodiments, the light diffusing material is a light diffusing film 320. The light diffusing film 320 comprises an adhesive backing 400 (see Figure 4) for adhering the light diffusing film 320 to the diffusing surface 318. In some embodiments, fresh, unused light diffusive film 320 comprises a backing liner 400 for covering the adhesive backing until application of the light diffusing film 320 to a target surface.

In some embodiments, the light diffusing film 320 does not comprise a backing liner. In this case, the light diffusing film 320 comprises a tactile adhesive that is activated under pressure. This means that the light diffusing film 320 does not adhere to itself when stored. In other embodiments, the light diffusing film 320 does not comprise an adhesive backing. In this case, an adhesive is applied to the diffusing surface 318 before the light diffusing film 320 is mounted on the diffusing surface 318.

In some embodiments, the light diffusing film 320 is comprises a width of 3.30mm. In some embodiments the width of the light diffusing film 320 is the same as the width of the diffusing surface 318. In this way, when the light diffusing film 320 is applied to the diffusing surface 318, the light diffusing film 320 covers the entire width of the diffusing surface 318. The light diffusing film 320 is flush with the edges of the diffusing surface 318 when mounted thereon.

The thickness of the light diffusing film 320 with the backing liner is approximately 0.30mm. The thickness of the light diffusing film without the backing liner is approximately 0.20mm and the thickness of the backing liner is approximately 0.1 mm. In other embodiments the width and the thickness of the light diffusing film 320 are varied. The light diffusing film 320 is flexible and is storable in a roll. In some embodiments, the roll is stored in a space (not shown) within the applicator carriage 102. In other embodiments, the roll can be stored external to, but coupled to the applicator carriage 102 such that the roll moves with respect to the elongate frame 300 when the film application tool 100 moves. Alternatively, the roll is external to and it not mounted on the film application tool 100. In this way, the roll does not move with respect to the elongate frame 300 when the film application tool 100 moves. This means that the length of the light diffusing film 320 can be any suitable length to match the length of the elongate frame 300. Advantageously, this means that the light diffusing film 320 can be dispensed and cut with a knife to match the length of the elongate frame 300. In contrast, a solid diffuser component must be pre-cut to the match the same length of the elongate frame 300. Use of a light diffusing film 320 makes the manufacturing process of the touch-sensitive device 328 simpler.

Turning back to Figure 1 , an embodiment of the film application tool 100 will now be discussed in further detail. The film application tool 100 is a tool for applying the light diffusing film 320 to the frame 300. Whilst the light diffusing film 320 is versatile for manufacture, the physical flexibility of the light diffusing film 320 can make installation of the light diffusing film 320 on the diffusing surface 318 challenging. For example, the flexible light diffusing film 320 can easily bend and deform during installation. This means that the light diffusing film 320 can bend and crease if handled incorrectly. Furthermore, installation of the light diffusing film 320 by hand on the frame 300 will mean the light diffusing film 320 will deviate from a straight line parallel with the longitudinal axis A-A of the elongate frame 300. Accordingly, if the light diffusing film 320 is not correctly installed on the diffusing surface 318, the light emitted from the light emitting components 302 will not propagate correctly over the touch surface 308.

The film application tool 100 comprises an applicator carriage 102. The applicator carriage 102 is arranged to be moveably mounted on the frame 300. In some embodiments, the applicator carriage 102 is slidable along the longitudinal axis A-A of the elongate frame 300. The applicator carriage 102 in some embodiments comprises convenient surfaces for the user to grip. In some embodiments the applicator carriage 102 comprises an indicator to show the user the direction that the film application tool 100 should be slid with respect to the elongate frame 300.

In some embodiments, the applicator carriage 102 comprises at least one coupling 104 to allow movement of the film application tool 100 along the longitudinal axis A-A of the elongate frame but prevent relative movement of the applicator carriage 102 with respect to a plane perpendicular to a longitudinal axis A-A of the elongate frame 300. For the purposes of clarity, the elongate frame 300 is not shown in Figure 1 . However, the longitudinal axis A- A is shown. In this way, the applicator carriage 102 can slide along the longitudinal axis A-A but cannot move in any other direction.

Indeed, the applicator carriage 102 does not move relative to the elongate frame 300 in a direction away from or to a top wall 106 of the applicator carriage 102. Likewise, the applicator carriage 102 does not relative to the elongate frame 300 in a direction away from or to a side wall 108 of the applicator carriage 102. This means that the film application tool 100 can only be inserted at one end of the elongate frame 300. Accordingly, the film application tool 100 cannot fall out or be manually removed from engagement with the frame 300 when the film application tool 100 is between the ends of the elongate frame 300.

The at least one coupling 104 can comprise at least one overlapping portion 1 10 for engaging an exterior surface 202 of the frame 300. The at least one coupling 104 can additionally or alternatively comprise at least one interior coupling portion 1 12 for engaging an interior surface of the frame 300. Optionally the film application tool provides a full grip around the elongate frame 300 profile.

The physical engagement between the elongate frame 300 and the film application tool 100 is best described in reference to Figure 2. Figure 2 shows a cross-sectional front view of the film application tool 100 mounted on the elongate frame 300.

The top wall 106 of the applicator carriage 102 comprises the at least one overlapping portion 1 10 of the coupling 104. The overlapping portion 1 10 further comprises a first movement restricting part 210. The first movement restricting part 210 of the overlapping portion 1 10 extends over an edge 200 and the top surface 324 of the elongate frame 300. An upper internal surface 202 of the first movement restricting part 210 engages an exterior surface 200 of the edge 200 of the frame 300. In other embodiments, the overlapping portion 1 10 engages one or more surfaces 324 of top wall 312, the side wall 316 and the bottom wall 314.

In the arrangement shown in Figure 3, the upper internal surface 202 of the first movement restricting part 210 prevents the frame 300 moving towards the top wall 106 relative to the applicator carriage 102.

The first movement restricting part 210 further comprises a hook portion 204 which extends around the edge 200 and down a bottom surface portion 220 of the bottom wall 314 of the elongate frame 300. In this way, the hook portion 204 prevents the elongate frame 300 from moving towards or away from the side wall 108 relative to the applicator carriage 102.

The overlapping portion 1 10 further comprises a second movement restricting part 206 which surrounds a protruding shelf 208 of the frame 300. A lower internal surface 212 of the second movement restricting part 206 engages another edge 214 of the frame 300. In this way, the second movement restricting part 206 prevents the frame 300 moving away from the top wall 106 relative to the applicator carriage 102.

As mentioned previously, the coupling 104 optionally comprises an interior coupling portion 1 12. The interior coupling portion 1 12 slides into one or more voids defined by the cross-sectional shape of the elongate frame 300. In some embodiments, the interior coupling portion 1 12 slides into the first mounting 306. In this way, the interior coupling portion 1 12 comprises a reciprocal shape to the first mounting 306. This means that the interior coupling portion 1 12 slids into the pair of slots of the first mounting 306. Since the interior coupling portion 1 12 engages multiple surfaces facing in different directions, the interior coupling portion 1 12 further limits the relative movement of the film application tool 100 with respect to the elongate frame 300.

In some embodiments, the at least one coupling 104 comprises only an interior coupling portion 1 12 or only an exterior overlapping portion 1 10. Indeed, it is possible for a single portion 1 12, 110 of the applicator carriage 102 to engage with a plurality of surfaces of the frame 300 such that relative movement of the film application tool 100 with respect to the frame 300 is restricted in two degrees of freedom. For example, in some embodiments, only the interior coupling portion 1 12 is used to engage the frame 300.

In other embodiments, the at least one coupling 104 engages restricts the relative movement of the application tool 1 10 with respect to the frame 300 in less than two degrees of freedom. For example, in some embodiments, the coupling 104 only comprises the exterior overlapping portion 1 10 (without the interior coupling portion 112 or the second movement restricting part 206 of the overlapping portion 1 10). In this way, the overlapping portion 1 10 only comprises the first movement restricting part 210. Furthermore, the hook portion 204 does not extend down the bottom wall 314, but only engages the edge surface 202.

Accordingly, the film application tool 100 engages the elongate frame 300 on the edge 200 and the top surface 324. Since the film application tool 100 uses only two reference surfaces 200, 324 for aligning the film application tool 100 with respect to the elongate frame 300, the film application tool 100 must be pushed by the user against the reference surfaces (e.g. the top surface 324 and the edge 200) when slid along the elongate frame 300.

It is preferable for the film application tool 100 to engage with the elongate frame 300 against a first pair of surfaces 200, 214 of the elongate frame 300 aligned with a first plane and a second pair of surfaces 324, 220 of the elongate frame 300 aligned in a second plane. In some embodiments the first 200, 214 and second 324, 220 pair of surfaces are perpendicular to each other. Accordingly, the first pair of surfaces are in planes which are perpendicular to the plane of the touch surface B-B and the second pair of surfaces are in planes which are parallel to the plane of the touch surface B-B. In some embodiments, the film application tool 100 can engage with more surfaces to further ensure alignment of the film application tool 100 with respect to the elongate frame 300. In this way, the first and second pairs of surfaces provide multiple reference surfaces for maintaining alignment of the film application tool 100 when it slides along the elongate frame 300. Maintaining this alignment means that the light diffusing film 320 will be applied uniformly along the length of the elongate frame 300.

The application carriage 102 comprises a channel 216 for receiving the diffusing surface 318 of the elongate frame 300. The diffusing surface 318 is arranged to slide within the channel 216. The channel 218 comprises an application surface 218 which is arranged to urge the light diffusing film 320 towards the diffusing surface 318 when in use. In some embodiments, when the film application tool 100 moves with respect to the elongate frame 300, the sliding action causes the light diffusing film 320 to be squashed onto the diffusing surface 318. The user may be required to squeeze the film application tool 100 and the elongate frame 300 together when sliding the film application tool 100 along the elongate frame 300. In some embodiments, the user may only be required to actively squeeze the film application tool 100 and the elongate frame together 300 when initially applying the light diffusing film 320 to the diffusing surface 318. The application surface 218 is angled with respect to a top wall 312 and a side wall 316 of the elongate frame when the film application tool 100 is mounted on the elongate frame 300. This means that the application surface 218 is arranged to abut the diffusing surface 318. Accordingly, the application surface 218 is orientated to apply the light diffusing film 320 in the correct orientation with respect to the diffusing surface 318. The application surface 218 is a reference surface for aligning the light diffusing film 320 with respect to the applicator carriage 102 and the elongate frame 300. In this way, the application surface 218 correctly aligns the light diffusing film 320. In some other embodiments, one or more other surfaces, walls, projections can engage the light diffusing film 320 to align the light diffusing film 320 with respect to the applicator carriage 102 and / or the elongate frame 300.

Additionally or alternatively, the clearance between the application surface 218 and the diffusing surface 318 when the film application tool 100 is mounted on the elongate frame 300 is less than the thickness of the light diffusing film 320. For example, the thickness of the light diffusing film is approximately 0.2mm and the clearance between the application surface 218 and the diffusing surface 318 is less than 0.2mm. In some embodiments the clearance is 0.15mm.

The channel 216 is arranged to feed the light diffusing film 320 on to the application surface 218 during operation. Operation of the film application tool 100 will now be discussed in reference to Figure 4.

Figure 4 shows a cross-sectional side view of the film application tool 100 mounted on the elongate frame 300.

The light diffusing film 320 is fed from a source of film such as a roll of film 320 (not shown, but indicated by the dotted line). Optionally, the light diffusing film 320 is fed into the channel 216 via a separator 404 (also shown in Figure 1 ). The separator 404 is mounted on an arm 402 projecting in front of the applicator carriage 102. In this way, the separator 404 separates the backing liner 400 from the light diffusing film 320 before the light diffusing film is fed into the channel 216. Initially, the position of the light diffusing film 320 with respect to the film application tool 100 is controlled by one or more walls of film application tool 100. In some embodiments, one or more walls of the channel 216 are reference surfaces which align the light diffusing film 320 with respect to the applicator carriage 102. In some embodiments, the separator 404 is a hook or a hole in the arm 402. The light diffusing film 320 is threaded through the separator 404 which ensures that the exposed adhesive backing of the light diffusing film 320 does not accidentally adhere to another surface before sticking to the diffusing surface 318. In other embodiments, the backing liner 400 is threaded through the separator 404 instead of the light diffusing film 320. In this way, the separator 404 is upstream of the channel 216 in the film feed path. The film feed path is shown by the bold black line in Figure 4. Broadly, the film feed path is from the separator 404, into the film channel 216 and on to the application surface 218 adjacent to the diffusing surface 318. The film feed path exits the film application tool 100 once the light diffusing film 320 has been applied to the diffusing surface 318. In this way, the feed direction of the light diffusing film 320 is controlled by the film application tool 100. Indeed, the aforementioned structure of the film application tool 100, provides reference surfaces which guide the direction and path that the light diffusing film 320 takes through the film application tool 100.

In some embodiments, the separator 404 is not required and the user can manually separate the backing liner 400 before starting the film application operation. However, the user has to manage a free end 410 of the backing liner 400 to make sure it does not snag in the film application tool 100 during use.

Once the backing liner 400 has been removed from the light diffusing film 320, the light diffusing film 320 is fed into the channel 216 between the application surface 218 and the diffusing surface 318. The user may have to press the film application tool 100 into the elongate film 300 to ensure that the end of the light diffusing film is correctly adhered to the diffusing surface 318. The user then moves the applicator carriage 102 in the direction of the arrow 408. In some embodiments, application surface 218 and / or one or more walls or structural elements of the applicator carriage 102 align the light diffusing film 320 with respect to the diffusing surface 318 before lamination.

In some embodiments, the application carriage 102 may comprise an indicator 408 shown the direction in which the film application tool 100 should be moved with respect to the elongate frame 300 during application of the film 320.

As mentioned previously, the user can grip the applicator carriage 102 to move the film application tool 100 along the elongate frame 300. However, in some embodiments, the tool 100 comprises a finger grip 406. The finger grip 406 allows the user to place one or more fingers thereon to pull the tool 100 along the frame 300.

Another embodiment will now be discussed in reference to Figure 5. Figure 5 shows a perspective view of another film application tool 500. The tool 500 comprises a different shape in order to fit with an elongate frame 600 (as shown in Figure 6) of a touch-sensitive device 700 with a different cross-sectional shape.

Similar to the embodiments described with reference to Figures 1 to 4, the film application tool 500 is mountable on a elongate frame 600 of the touch-sensitive device 700 and slidable in a direction along the longitudinal axis A-A of the elongate frame 600.

The film application tool 500 differs from the previously described film application tool 100 in that the light diffusing film 320 is fed to the application surface 502 and mounted on the diffusing surface 602 via a different film feed path.

The engagement between the film application tool 500 and the elongate frame is best shown from Figure 6. Figure 6 shows a front cross-sectional view of the film application tool 500 mounted on the elongate frame 600. The film application tool 500 mounts to the elongate frame 600 in a similar way to the film application tool 100 as previously discussed in reference to Figures 1 to 4. Turning back to Figure 5, the film application tool 500 has a coupling portion 504 and an overlapping portion 506 and an interior coupling portion 508. The overlapping portion 506 and the interior coupling portion 508 physically engage the elongate frame 600 in a similar way to the previously described embodiments. The interior coupling portion 508 comprises a different cross- sectional shape to the interior coupling portion 1 12 because the interior cross- sectional shape of the elongate frames 300, 600 in the different embodiments are different. In this way, the different elongate frames 300, 600 are used for different shapes and sizes of touch-sensitive devices 328, 700. The interior coupling portions 112, 508 can be any suitable cross-sectional shape reciprocal to the cross-sectional shape of the elongate frame 300, 600.

Similar to the previous embodiments, the film application tool 500 engages with the elongate frame 600 against a first pair of surfaces 604, 606 of the elongate frame 600 aligned with a first plane and a second pair of surfaces 608, 610 of the elongate frame 610 aligned in a second plane. The first 604, 606 and second 608, 610 pair of surfaces are perpendicular to each other.

In this way, the first and second pairs of surfaces 604, 606, 608, 610 provide multiple reference surfaces for maintaining alignment of the film application tool 500 when it slides along the elongate frame 600. The film application tool 500 can phyiscally engage a plurality of surfaces to maintained relative aligement between the film application tool 500 and the elongate frame 600. For the purposes of brevity, the coupling 504 will not be described in any further detail.

Briefly turning to Figures 7a, 7b, the elongate frame 600 will be described in further detail. Figures 7a and 7b show a side cross-sectional view of a touch- senstive device 700 comprising the elongate frame 600. The elongate frame 600 comprises the touch surface 308, the substrate 304 and the light emitting component 302 mounted on the elongate frame 600. In contrast to the previous embodiments, the substrate 304 is mounted in a plane which is substantially perpendicular to the plane of the touch surface 308. However in other embodiments, although now shown, the substrate 304 can be arranged in a plane which is substantially parallel to the plane of the touch surface 308. Figures 7a and 7b show two variants of how the substrate 304 is mounted with respect to the frame 600.

In Figure 7a the substrate 304 is mounted completely beneath the touch surface 308. In this way, the light emitting component 302 is aligned with the light diffusing film 320 in a similar way to the arrangement shown in Figure 3. That is, the light emitted from the light emitting component 302 propagates through the touch surface 308 before the emitted light reaches the light diffusing film 320.

In Figure 7b, the substrate 304 extends around the touch surface 308. The substrate 304 comprises a mounting 702 for receiving and securing the touch surface 308. The mounting 702 as shown in Figure 7b is a groove for receiving the touch surface 308. In other embodiments, the mounting 702 can be a fastener such as a screw, rivet, glue or any other suitable fastening for mounting the touch surface 308 to either the substrate 304 or the elongate frame 600. The light emitting component 302 is positioned above the touch surface 308. This means that the light emitted from the light emitting component 302 does not propagate through the touch surface 308.

The touch-sensitive device 700 may comprise other components such as seals, windows and so on which are not shown for the purposes of clarity.

Turning back to Figures 5, the film application tool 500 will be described in further detail. The applicator carriage 102 comprises an internal film channel 510 having a first opening 512 that intersects with the application surface 502. Both the internal film channel 510 and the application surface 502 are reference surfaces for aligning the light diffusing film 320 with respect to the film applciation tool 500 and / or the elongate frame 300. The film channel 510 comprises a second opening 514 and the film feeding path extends between the first opening 512 and the second opening 514. Optionally, the film application tool 500 comprising a projecting smoothing arm 516 arranged to engage the light diffusing film 320 that has been applied to the diffusion surface 602 after the application surface 502 has engaged the light diffusing film 320. The smoothing arm 516 is a resilient flexible projection and pushes against the diffusing surface 602 when the film application tool 500 is mounted on the elongate frame 600.

The smoothing arm 516 optionally comprises a cushion 802 (see Figure 8) arranged to engage the light diffusing film 320 which has been deposited on the diffusing surface 602. This cushion 802 is arranged to apply an even pressure across the width of the light diffusing film 320 mounted on the diffusing surface 602. The cushion 802 is mounted on the smoothing arm 516 at an angle with respect to the longitudinal axis A-A of the elongate frame 600. In this way, the cushion 802 is urged against the light diffusing film 320 mounted on the diffusing surface 602 because the smoothing arm 516 urges the cushion 802 against the diffusing surface 602. The smoothing arm 516 and the cushion 802 can optionally be combined with the embodiments as described in reference to Figures 1 to 4.

The film application tool 500 further comprises a finger grip 518 projecting from the applicator carriage 102. The finger grip 518 projects in a direction perpendicular to the longitudinal axis A-A of the elongate frame 600 when the film application tool 500 is mounted on the elongate frame 600. This means that the finger grip 518 projects beyond the elongate frame 600 and makes grip and actuation of the film application tool 500 easier.

As mentioned previously, the light diffusing film 320 passes through a film channel 510 which intersects with the application surface 502. This will be described in further detail together with operation of the film application tool 500 in reference to Figures 8 and 9. Figures 8 and 9 show a cross-sectional side view of the film application tool 500 mounted on the elongate frame in a first mode of operation and a second mode of operation. The modes of operation as shown in Figures 8 and 9 can both be used to apply the light diffusing film 320 to the diffusing surface 602. The film application tool 500 comprises a structure that allows both the first and second modes of operation. However in other embodiments, the film application tool 500 can comprise the structure of channels for operation of only the first mode or the second mode.

Turning to Figure 8, the light diffusing film 320 is fed into the second opening 514 of the film channel 510 in the direction shown by the arrows. At the point that the light diffusing film 320 enters the second opening 514, the light diffusing film also comprises the backing liner 400. The light diffusing film 320 passes through the film channel 510 to the first opening 512 of the film channel 510. As the light diffusing film 320 emerges from the first opening 512 of the film channel 510, the film 320 is positioned on the application surface 502. The backing liner 400 passes over a separator 800 which separates the light diffusing film 320 from the backing liner 400. In some embodiments, the separator 800 is the lip 800 of the first opening 512 of the film channel 510. However, in other embodiments, the separator 800 can be a peg or other structural feature for the backing liner 400 to pass around. The backing liner 400 changes direction and passes over the lip 800 of the first opening 512. In this way, the backing liner 400 is pulled in a direction which is parallel with the direction of travel of the film application tool 500. At the same time, the light diffusing film 320 continues straight and is squeezed between the application surface 502 and the diffusing surface 602 in region 804 of the application carriage 102. The light diffusing film 320 passes under the cushion 802 mounted on the smoothing arm 516 which smooths the light diffusing film 320 on to the diffusing surface 602. One or more other parts of the film application tool 500 can also urge the light diffusing film 320 on to the diffusing surface 602.

The arrangement as shown in Figure 8 does not cause the light diffusing film 320 to undergo excessive bends and creasing of the film is minimised. This is because the separator causes the backing liner 400 undergoes a change in direction which removes the backing liner 400 from the light diffusing film 320. As mentioned, previously, the separator 800 is optional because the film may not have a backing liner 400 and therefore may not need a separating operation before the light diffusing film 320 is applied to the diffusing surface 602. In some embodiments, the backing liner 400 can be pulled which exerts a translational force on the separator 800. The translational force overcomes the frictional forces between the film application tool 100 and the elongate frame 300. In this waym the user can pull the backing liner 400 which causes the film application tool 100 to move along the elongate frame 300 and apply fresh light diffusing film 320. The user may need to ensure that the backing liner 400 does not snag in the film application tool 100 when moving the film application tool 100.

Figure 9 shows an alternative embodiment of applying the light diffusing film 320 to the diffusing surface 602. The film application tool 500 is the same as the film application tool 500 shown in Figures 5 to 8.

The applicator carriage 102 further optionally comprises a second film channel 900 for receiving the light diffusing film 320. The film 320 is fed into the second film channel 900 at a first opening 902 and exits at a second opening 904 on the opposite side of the applicator carriage 102. As the film 320 exits the second opening 904, the film 320 is fed into the second opening 514 of the first channel 510 as described in reference to Figure 8.

However, in contrast to the embodiments as described in reference to Figure 8, the film 320 bends around a separator 906. Since the light diffusing film 320 bends around the separator 906, the feeding path of the light diffusive film 320 reverses direction between the first film channel 510 and second film channels 900.

In some embodiments, the separator 906 is a curved connection portion which is located between the first film channel 510 and the second film channel 900. Optionally the radius of curvature of the curved connection portion 906 is above a film creasing threshold radius. In this way, when the light diffusing film 320 bends around the separator 906, the film does not crease. In a less preferred embodiment, the radius of curvature of the separator 906 can be smaller and cause creases in the film. This may be acceptable if the creases do not significantly affect the diffusion of the light above the touch surface 308. In some embodiments, the separator 906 is a pulley wheel (not shown) rotatably mounted to the applicator carriage 102 to decrease the frictional forces between the film and the applicator carriage 102. In other embodiments, the separator 906 can project out the front of the applicator carriage 102 to provide a surface with a larger radius for the film 320 to bend around.

As the light diffusing film 320 bends around the separator 906, the backing liner is detached from the light diffusing film 320. The light diffusing film 320 then reverses its direction of travel, as shown by the arrow, and enters the first film channel 510 to guide the light diffusing film 320 to the application surface 502. The application of the light diffusing film 320 to the diffusing surface 602 is the same as previously discussed in reference to Figure 8. In some embodiments, the film application tool 100, 500 can be used to apply other materials to the elongate frame 300, other than the light diffusing film 320. For example flexible seals, wiring, and any other laminar, flat material can be mounted on to a receiving surface of the elongate frame. In another embodiment two or more embodiments are combined. Features of one embodiment can be combined with features of other embodiments.

Embodiments of the present invention have been discussed with particular reference to the examples illustrated. However it will be appreciated that variations and modifications may be made to the examples described within the scope of the invention.