Improved touch sensing device

Abstract

A touch sensing device is disclosed, the touch sensing device comprising: a panel having a touch surface; emitters and detectors arranged along an outer periphery; and a light guide arranged adjacent to the periphery and including a light guide surface, the emitters and / or detectors arranged facing a rear surface of the panel and emitting and / or receiving light through channels in a frame element, the channels arranged facing the rear surface and extending in a direction of an axis normal to the touch surface, the light guide surface and the channels arranged on opposite sides of the panel and overlapping in a planar direction, the light guide surface receiving light from the emitters or directing light to the detector through the panel and the channels in the direction of the normal axis. A method of manufacturing a frame element for a touch sensing device is also disclosed.

Description

[Technical field]

[0001] The present invention relates to touch-sensing devices that operate by propagating light over a panel, and more specifically to optical and mechanical solutions for controlling and adjusting the light path over the panel through fully or partially randomized refraction, reflection or scattering. [Background technology]

[0002] In one category of touch-sensing panels, known as "surface optical touch systems," a set of light emitters are positioned around the perimeter of a touch surface that emits light that is reflected and travels and propagates across the touch surface. Also positioned around the perimeter of the touch surface are a set of light detectors that receive the light from the set of emitters from above the touch surface. Thus, a grid of intersecting light paths, also called scan lines, is formed above the touch surface. An object that touches the touch surface attenuates the light on one or more of the scan lines of light, causing a change in the light received by one or more detectors. The light received by the detectors can be analyzed to determine the object's position (coordinates), shape, or area.

[0003] The optical and mechanical properties of the touch sensing device affect the scattering of light between the emitter / detector and the touch surface, and accordingly affect the detected touch signal. For example, the width of the scan line affects factors of touch performance such as detection ability, accuracy, resolution, and the presence of reconstruction artifacts. Problems with prior art touch detection systems relate to suboptimal performance with respect to the factors mentioned above. Furthermore, variations in the alignment of opto-mechanical components can affect the detection process, which can lead to suboptimal touch detection performance. Factors such as signal-to-noise ratio, detection accuracy, resolution, and the presence of artifacts in the touch detection process can be affected. Prior art systems aim to improve those factors, e.g., detection accuracy, but often with compromises in that more complex and expensive opto-mechanical modifications need to be incorporated into the touch system. This usually results in a less compact touch system and a more complex and expensive manufacturing process. Summary of the Invention

[0004] The objective is to at least partially overcome one or more of the above-mentioned limitations of the prior art.

[0005] One objective is to provide a touch sensitive device that is compact, uncomplicated, robust and easy to assemble.

[0006] Another object is to provide an "on-surface" based touch sensing device that makes efficient use of light.

[0007] One or more of these objects, as well as other objects that may become apparent from the following description, are at least partly achieved by a touch sensing device according to the independent claims, embodiments of which are defined by the dependent claims.

[0008] According to a first aspect, there is provided a touch sensing device comprising a panel defining a touch surface extending in a plane having a normal axis, a plurality of emitters and detectors arranged along an outer periphery of the panel, and a light guide arranged adjacent to the periphery and including a light guide surface, the emitters arranged to emit light and the light guide surface arranged to receive light and guide light across the touch surface, the panel having a back surface opposite the touch surface, the emitters and / or detectors arranged opposite the back surface to emit and / or receive light via channels in a frame element, the channels arranged opposite the back surface and extending in the direction of the normal axis, the light guide surface and the channels arranged opposite each other across the panel and overlapping in the direction of the planar surface, whereby the light guide surface receives light from the emitters or guides light to the detectors via the panel and the channels in the direction of the normal axis.

[0009] According to a second aspect, there is provided a method of manufacturing a frame element for a touch sensing device, the method comprising the steps of extruding the frame element to form a light guide and a cavity adapted to receive a substrate with an emitter and / or a detector, and milling a wall of the cavity to form a channel such that, in use, a light guide surface of the light guide receives light from the emitter or directs light to the detector via the channel.

[0010] Some embodiments of the present disclosure provide a more compact touch sensitive device.

[0011] Some embodiments of the present disclosure provide a touch sensitive device that is low cost to manufacture.

[0012] Some embodiments of the present disclosure provide a touch-sensing device with a reduced number of electro-optical components.

[0013] Some embodiments of the present disclosure provide a more robust touch sensitive device.

[0014] Some embodiments of the present disclosure provide a touch sensitive device that is more reliable to use.

[0015] Some embodiments of the present disclosure reduce the effects of stray light.

[0016] Some embodiments of the present disclosure reduce ambient light sensitivity.

[0017] Some embodiments of the present disclosure provide a touch sensitive device with a better signal-to-noise ratio of the detected light.

[0018] Some embodiments of the present disclosure provide a touch sensitive device with improved resolution and detection accuracy of small objects.

[0019] Some embodiments of the present disclosure provide a touch-sensitive device with fewer detection artifacts.

[0020] Some embodiments of the present disclosure provide a touch sensitive device with more uniform coverage of scan lines across the entire touch surface.

[0021] Further objects, features, aspects and advantages of the present disclosure will become apparent from the following detailed description, the appended claims and the drawings.

[0022] It is to be understood that in this specification the term "comprising" is used to specify the presence of stated features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps, components or groups thereof. [Brief description of the drawings]

[0023] These and other aspects, features and advantages of which embodiments of the invention are possible will become apparent or apparent from the following description of embodiments of the invention when read in conjunction with the accompanying drawings. [Figure 1]FIG. 1a is a schematic side sectional view of a touch detection device according to an embodiment of the present disclosure. FIG. 1b is a schematic side sectional view of a touch detection device according to an embodiment of the present disclosure. FIG. 1c is a schematic top view of a touch detection device according to an embodiment of the present disclosure. FIGS. 1d and 1e are schematic top views of an example of a prior art touch detection device. [Diagram 2] FIG. 2 is a schematic side sectional view of a touch detection device according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 is a schematic side sectional view of a touch detection device according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a schematic side sectional view of a touch detection device according to an embodiment of the present disclosure. [Diagram 5] FIG. 5 is a schematic side sectional view of a touch detection device according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a schematic side sectional view of a touch detection device according to an embodiment of the present disclosure. [Figure 7] FIGS. 7a to 7c are schematic side sectional views of a frame element for a touch detection device according to an embodiment of the present disclosure. [Figure 8] FIGS. 8a and 8b are schematic side sectional views of details of a frame element for a touch detection device according to an embodiment of the present disclosure. FIG. 8c is a schematic side sectional view of details of a frame element for a touch detection device according to an embodiment of the present disclosure. FIG. 8d is a schematic view (I) seen along the direction of the plane of the touch surface of details of a frame element including a light guiding surface for a touch detection device according to an embodiment of the present disclosure, a schematic view (II) of a detailed section of the light guiding surface of (I), and a side view (III) of the section of (II). [Figure 9] FIG. 9a is a schematic side sectional view of a touch detection device according to an embodiment of the present disclosure. FIG. 9b is a schematic side sectional view of a touch detection device according to an embodiment of the present disclosure. [Figure 10]Fig. 10a is a flow chart of a method for manufacturing a frame element for a touch sensitive device according to an embodiment of the present disclosure, Fig. 10b is another flow chart of a method for manufacturing a frame element for a touch sensitive device according to an embodiment of the present disclosure, and Fig. 10c is another flow chart of a method for manufacturing a frame element for a touch sensitive device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, embodiments of the present invention will be presented for the specific example of a touch-sensing device. Throughout the description, the same reference numerals will be used to identify corresponding elements.

[0025] FIG. 1a is a schematic diagram of a touch sensitive device 100 including a panel 101 defining a touch surface 102 extending in a plane 103 having a normal axis 104. The panel 101 is a light transmissive panel. The touch sensitive device 100 includes a plurality of emitters 105 and detectors 106 disposed along a perimeter 107 of the panel 101. FIG. 1a shows only the emitters 105 for clarity of presentation, while FIG. 1b shows how light is transmitted from the emitters 105 across the touch surface 102 to the detectors 106. The touch sensitive device 100 includes a light guide 108 disposed adjacent to and along the perimeter 107. The light guide 108 includes a light guide surface 109. The emitters 105 are positioned to emit light 110, and the light guide surface 109 is positioned to receive the light 110 and direct the light across the touch surface 102 of the panel 101. After propagating across the touch surface 102, the light is reflected to the detector 106 via a corresponding light guide surface 109, as shown in FIG. 1b. FIG. 1c is a schematic top view of the touch sensitive device 100. FIG. 2 also shows a schematic reflection from the emitter 105 to the detector 106. The panel 101 includes a back surface 111 opposite the touch surface 102, and the emitter 105 and / or the detector 106 are disposed opposite the back surface to emit and / or receive light 110 via channels 112 in a frame element 113 of the touch sensitive device 100. The channels 112 are disposed opposite the back surface 111 and extend in the direction 104' of the normal axis 104, i.e., substantially parallel to the normal axis 104. The light guide surface 109 and the channels 112 are disposed opposite each other across the panel 101 and overlap along the direction of the plane 103. That is, there is an overlap in the horizontal positions of the light guiding surface 109 and the channels 112 of FIG. 1a, resulting in a light path extending vertically from the light guiding surface 109 to the channels 112. The light guiding surface 109 is positioned to receive light 110 from the emitter 105 or direct light to the detector 106 in a direction 104' of the normal axis 104, through the panel 101, and through the channels 112. The main optical axis 110' of the light emission can essentially extend along the direction 104', although it should be understood that the light also has an angular spread about the optical axis 110', as shown in FIG. 1a.As illustrated in FIG. 1a and FIG. 4, having the light guide surface 109 disposed above the channel 112 can provide effective shielding of ambient or system stray light. Thus, the amount of ambient or stray light reflected toward the detector 106 can be minimized, improving the signal-to-noise ratio. By having the emitter 105 emitting light 110 in the direction 104' of the normal 104, i.e., by having the optical axis 110' of the light 110 substantially parallel to the normal axis 104, as further illustrated in FIG. 1a and FIG. 4, the dimensions of the touch sensitive device 100 along the periphery can be easily reduced. The cross-sectional footprint of the emitter 105 and detector 106 assembly can be minimized, for example, in the direction of the plane 103 in FIG. 1a and FIG. 4. The above arrangement can also minimize angular reflections relative to the panel 101, which can be advantageous in some applications. Propagating the light 110 through the panel 101 allows the panel 101 to act as a sealing element for the emitter 105 and detector 106 from the environment, providing a further synergistic effect in providing a compact touch sensing device 100 and minimizing the number of optical components. The panel 101 can thus act as a sealing part to protect the electronics from, for example, liquids and dust. This allows for the omission of further optical sealing elements. This has the further advantage that the angle at which the light scatters across the panel 101 can be further increased, reducing reflection losses and improving the coverage of the scan line across the panel 101. For example, Fresnel reflection losses can be minimized, as will be further described with respect to FIG. 1d. FIG. 1d shows an example of a prior art touch sensing device, where the emitter 401 and detector 402 are arranged along the sides of the touch surface 403, and the optical sealing components 404 are arranged along the sides. An optical encapsulation component 404 is disposed above the touch surface 403 and between opposing reflective surfaces that reflect light across the touch surface 403 (ie, at a location corresponding to the location of the light guide surface 109).Having such additional optical encapsulation components 404 can introduce undesirable reflections from light propagating above the touch surface 403, especially when the light is reflected at high angles along the sides of the touch surface 403, as shown by reflection 406 in Fig. 1d. Fig. 1e is a more detailed view of the example of Fig. 1d, showing additional reflections 405, 405' at each interface of such additional optical encapsulation components 404, 404'. Such reflections 405, 405' can lead to significant loss of light, especially when having additional optical encapsulation components 404, 404' along each side of the touch surface 403.

[0026] Reducing the number of components can be particularly advantageous in some applications where further compactness is desired. This can also reduce the cost of the touch sensing device 100. As described in more detail below, the light guide 108 can be formed as part of the frame element 113, such that the light guide surface 109 is formed in the material of the frame element 113. This can further reduce the number of opto-mechanical components along the path of the light from the touch surface 102 to the emitter 105 and detector 106. This also reduces the number of components that require alignment, simplifying assembly. The result is a particularly compact and robust touch sensing device 100 that uses the detection light more efficiently. This can improve touch detection performance while reducing complexity and cost.

[0027] As illustrated in FIGS. 2 and 4, the angle (v) between the light guide surface 109 and the plane 103 of the touch surface 102 may be less than 45 degrees. This can reduce the amount of undesired reflections of light across the touch surface 102 (which may cause artifacts or other disturbances when detecting touch signal attenuation), also illustrated by the reflection 406 in FIG. 1d. Alternatively, if the angle (v) is less than 45 degrees, undesired reflections of light may be reflected out of the plane 103. The angle (v) may be in the range of 41-44 degrees in some examples to particularly advantageously reduce undesired reflections of light. The angle (v) may be greater than 45 degrees. For example, the angle (v) may be in the range 46-49 degrees to also reduce undesired reflections of the type illustrated by the scan line 406 in FIG. 1d. It should be appreciated that the advantageous advantages discussed above for touch sensing device 100, i.e., less complex, more compact, and cost-effective manufacturing process, apply to both examples where angle (v) is greater than 45 degrees and less than 45 degrees.

[0028] The panel 101 has an edge 114 extending between the touch surface 102 and the back surface 111. The channels 112 have a width (d) between a first channel wall 115a disposed closest to each edge 114 of the panel 101 and an opposing second channel wall 115b, as shown, for example, generally in Figures 2 and 5. 1 ) and extends in a direction parallel to the plane 102. The first channel wall 115a can extend at an angle 116 with respect to the direction 104' of the normal axis 104. Having an angled channel wall 115a can reduce the amount of ambient light that is reflected towards the detector 106. Most of the ambient light that is reflected off the channel wall 115a will be reflected back past the detector 106 while also reducing the light from the emitter 105 that passes directly past the light guiding surface 109, which can cause stray light issues.

[0029] It should be noted that the light guide 108 has an edge portion 121 that corresponds to where the light guide 108 is disposed closest to the touch surface 102, as illustrated in Figures 3 and 5. The light guide surface 109 may extend from the edge portion 121 of the light guide 108 to a protrusion 117 of the light guide 108, as shown generally in Figures 3 and 5. The protrusion 117 may extend in a direction parallel to the plane 103 to block ambient light from being reflected towards the channel 112.

[0030] Channel 112 width (d 1 ) can be further varied to optimize the amount of light 110 emitted towards the light guiding surface 109 while providing sufficient shielding from ambient or stray light. The position of the first and second channel walls 115a, 115b along the direction of the plane 103 relative to the emitter 105 and / or detector 106 can be optimized according to the specific embodiment. In one example, the position of the second channel wall 115b is aligned with the position of the protrusion 117 along the direction of the plane 103, as shown diagrammatically in FIG. 3. This is considered to be particularly advantageous for shielding ambient or stray light. At the same time, blocking of the emitted light 110 can be avoided when optimizing the position of the emitter 105 relative to the center of the channel 112. As will be further explained below, the surface properties of the channel walls 115a, 115b can also be adjusted to avoid loss of detected light or to reduce the effect of ambient or stray light.

[0031] The emitter 105 and / or the detector 106 can be attached to a substrate 119. The substrate 119 can include a chamfered edge 120a arranged opposite a corresponding engagement surface 120b of the frame element 113. The engagement surface 120b of the frame element 113 can be angled 122 with respect to the normal axis 104, as shown diagrammatically in Fig. 3 and Fig. 6. This allows the substrate 119 to be effectively fixed in the correct position with respect to the frame element 113. This allows the emitter 105 and / or the detector 106 to be easily and reliably aligned with respect to the light guide surface 109, and thus the signal to be easily optimized. At the same time, as illustrated in Fig. 3, providing the angled surface 120b of the frame element 113 allows at least a portion of the second channel wall 115 closest to the substrate 119 to be removed, reducing the risk of blocking the light from the emitter 105 or to the detector 106 (see, for example, Fig. 2 vs. Fig. 3).

[0032] The walls 115a, 115b of the channel 112 can be provided with a diffuse light scattering surface. Thus, the walls 115a, 115b can also be used as reflective elements, which allows for better light management, e.g. recycling light and reflecting light from lost directions towards the light guide surface 109. Thus, a large part of the emitted light 110 can be utilized. At the same time, the surface of the walls 115a, 115b can be tailored to provide a specular component of the reflected light. This allows for improved direction of the reflected light, e.g. directing the light towards the light guide surface 109 above the panel 101. The proportion of the specular component of the reflected light can be varied by performing various surface treatments on the channel walls 115, 115b, e.g. affecting their surface roughness. The reflective properties of the light guide surface 109 can also be varied by such surface treatments, which include etching, bead blasting, sand blasting, brushing and / or anodizing, as described in more detail below.

[0033] 3 and 4, supports 123 may be attached to the substrate 119. The supports 123 may extend in a direction parallel to the plane 103 between the substrate 119 and frame walls 124a, 124b of the frame element 113. The supports 123 may facilitate alignment of the substrate 119 with respect to the frame element 113, which may facilitate manufacturing and allow accurate positioning of the emitter 105 and / or detector 106 with respect to the frame element 113.

[0034] The frame element 113 may be shaped to form a cavity 125. The emitters 105 and / or detectors 106 may be attached to a substrate 119, which may be disposed within the cavity 125 such that the emitters 105 and / or detectors 106 are disposed closer to the respective edge 114 of the panel 101 than the substrate 119, as shown diagrammatically in FIG. 3. This allows the width of the bezel, i.e. the width of the light guide 108 along the direction of the plane 103, to be minimized since the emitters 105 and / or detectors 106 are disposed closer to the edge 114 of the panel 101 while maintaining the advantageous sealing effect of the panel 101 as described above. This provides a more compact touch sensing device 100.

[0035] In particular, the cavity 125 has a width (d) between a first frame wall 124a disposed closest to each edge 114 of the panel 101 and an opposing second frame wall 124b. 2 ) and may extend in a direction parallel to the plane 103. The substrate 119 may be disposed within the cavity 125 such that the emitter 105 and / or the detector 106 are disposed closer to the first frame wall 124a than the substrate 119, as illustrated in FIG. 3. This allows the width of the bezel along the direction of the plane 103 to be minimized.

[0036] 2, the substrate 119 may extend in an elongated shape in the direction 104′ of the normal axis 104. This may reduce the dimensions of the touch sensitive device 100 in a direction perpendicular to the normal axis 104, which may be desirable in some applications where the amount of space in this direction is limited and / or the ratio of the available touch surface 102 to the surrounding frame components needs to be optimized. The combination of extending the substrate 119 along the direction 104′ of the normal axis 104 and positioning the emitter 105 and / or detector 106 closer to the first frame wall 124a than the substrate 119 may allow for particularly efficient use of space along the direction of the plane 103.

[0037] FIG. 9a shows an example where the substrate 119 extends along the direction of the plane 103, which allows compact dimensions to be achieved along the direction of the normal axis 104. This may be advantageous, especially when utilized with a flat display panel 301, in which case the dimensions in the direction of the plane 103 around the displayed area may increase. FIG. 9b shows another example where the substrate 119 extends along the direction of the plane 103, but the emitter 105 and / or detector 106 are arranged to emit / receive light in the direction of the plane 103 via a reflective surface 135. This allows compact dimensions to be achieved along the direction of the normal axis 104. The reflective surface 135 may be a specular reflective surface.

[0038] The light guide surface 109 may be an anodized metal. The light guide surface 109 may also be surface treated to diffusely reflect the light 110 towards the touch surface 102. The anodization process changes the microscopic texture of the surface 109 and increases the thickness of the native oxide layer on the surface 109. The thickness and porosity of the anodized oxide surface may be varied. The anodized surface may be dyed a variety of colors to achieve a desired appearance. Some colors may provide advantageous reflectance in the infrared range, such as over 80%, for example when aluminum is anodized black, gray or silver. Other metals may provide advantageous reflectance properties, such as silver. It may be particularly advantageous to use wavelengths above 940 nm, where many anodized materials start to reflect significantly. Also, different alloys, such as aluminum, may be used to provide different colors. Different surface treatments on the anodized metal or alloy may change the diffuse and specular components of the reflected light. This variation in surface roughness may optimize the ratio of the above reflected components. The directionality of the reflected light is increased by increasing the specular component, while the amount of random scattering increases with the diffuse component. For example, increasing the specular component of the reflected light from the light guide surface 109 can increase the intensity of the scan line. In such a case, the number and / or position of the emitters 105 can be varied to compensate for the narrowing of the scan line due to the reduction in diffuse light scattering. Thus, in some instances, the reflective properties of the light guide surface 109 can be optimized while still allowing for the desired aesthetic appearance of the anodized surface.

[0039] Various surface roughness characteristics can be achieved by various processes, such as etching, sandblasting, bead blasting, machining, brushing, polishing, and processes such as anodization as mentioned above. In one example, the light guide surface 109 can have a surface roughness defined by a slope RMS (Δq) of 0.1 to 0.35. For advantageous diffusivity, the slope RMS (Δq) can be 0.1 to 0.25. A high value can reduce the strength of the signal, and a signal that is too low can reduce the angle (φ) at which the light spreads in the plane 103 across the touch surface 102 (the angle shown as φ in the example of FIG. 1c), leading to a more tolerant sensing system limited by the viewing angles of the emitter and detector. Also, the width of the scan line can become too narrow. In another example, the slope RMS (Δq) can be 0.13 to 0.20 for particularly advantageous diffusivity that provides an optimized signal strength and touch detection process while maintaining advantageous power consumption of the components of the touch sensing device 100.

[0040] With appropriate slope variation, the height variation of the blasted or etched surface is typically in the range of 1-20 um. However, optimizing the slope RMS (Δq) as described above provides the most effective tuning of the reflective properties. In some examples, the light guide surface 109 has a low roughness. In one example, the light guide surface 109 may be an anodized metal surface that has not undergone any treatment to increase the surface roughness. In such a case, the light guide surface 109 may be anodized directly after the extrusion process. The light guide surface 109 may be mirror-like in such a case, i.e., the surface 109 has not undergone any treatment to achieve light diffusion. In such a case, the slope RMS (Δq) may be 0-0.1 to provide a mirror-like surface. Such a surface may be advantageous in applications where a narrow scan line is desired for a particular touch detection process. For example, when it is advantageous to increase the amount of detection light available in a desired direction across the touch surface 102.

[0041] The frame element 113 may include the light guide 108. That is, the light guide 108 is formed as an integral part directly from the frame element 113, for example by extrusion. The frame element 113 and the light guide 108 may be formed from various metals, such as aluminum. Thus, the light guide surface 109 may be an anodized metal surface of the frame element 113. In this way, the frame element 113 may be utilized as a diffuse light scattering element without providing a separate optical component for diffuse light scattering. Thus, the number of components may be further reduced with such an integrated light guide surface 109. This further eliminates the need to have an additional optical sealing element to protect such a separate optical component. Thus, a more robust touch sensing device 100 that is easier to assemble is provided. Furthermore, the surfaces of the walls 115a, 115b of the channel 112 may be metal surfaces of the frame element 113. The reflective properties of the walls 115a, 115b may be adjusted as described above with respect to the light guide surface 109. The frame element 113 may form a cavity 125 in which the emitter 105 and / or detector 106 are disposed. Thus, the frame element 113 may be formed as a single integral part having the light guiding surfaces 109, 115a, 115b, the cavity 125 for the substrate 119, and any mounting interface 129 to a back frame 302 for the display 301, as shown diagrammatically in Figure 1a. This may minimize the number of opto-mechanical components of the touch sensing device 100, and may provide a touch sensing device 100 that is uncomplicated and particularly robust, suitable for mass production.

[0042] The light guide 108 may include an outer surface 126 opposite the light guide surface 109, as shown for example in FIG. 2. The light guide surface 109 may have a higher reflectivity than the outer surface 126. Various surface treatments on the light guide 108 of the frame element 113 may allow for an effective and optimized scattering of light across the touch surface 102 via the light guide surface 109, while the outer surface 126 facing the user may have a low reflectivity to minimize reflection of light towards the user. This may further provide a desired appearance without affecting the optical function (e.g., avoiding a too large slope that would make the light guide surface 109 too unreflective). A particularly efficient use of manufacturing materials may be achieved, since a single, integral section of the frame element 113 may be uniquely treated to achieve the desired function of light reflectivity. For example, alignment of separate optical components may not be required.

[0043] In one example, the walls 115a, 115b of the channel 112 can have a higher specular reflectance than the light guide surface 109. This can provide a more controlled reflection of the emitted light towards the light guide surface 109. The light guide surface 109 can provide a larger diffuse component to increase the width of the scan line across the touch surface 102.

[0044] In one aspect, a touch sensing device 100 is provided that includes a panel 101 defining a touch surface 102 extending in a plane 103 having a normal axis 104. A plurality of emitters 105 and detectors 106 are disposed along a perimeter 107 of the panel 101. A light guide 108 is disposed adjacent the perimeter 107 and includes a light guide surface 109. The emitters 105 are disposed to emit light 110, and the light guide surface 109 is disposed to receive the light 110 and direct the light 110 across the touch surface 102. The panel 101 includes a back surface 111 opposite the touch surface 102. The emitters 105 and / or detectors 106 are disposed against the back surface 111 for emitting and / or receiving light via channels 112 in a frame element 113. The light guide surface 109 receives light from the emitter 105 through the panel 101 and through the channel 112, or guides light to the detector 106. The frame element 113 is formed of metal and includes the light guide 108, with the light guide surface 109 being an anodized metal surface of the frame element 113. The frame element 113 may also define a cavity 125 within which the emitter 105 and / or detector 106 are disposed such that the optical axis 110' of the emitted light 110 is essentially parallel to the normal axis 104. Thus, by providing a compact touch sensing device 100 with improved signal-to-noise ratio and increased touch detection performance, the touch sensing device 100 may provide the advantageous benefits discussed above.

[0045] FIG. 10a is a flow chart of a method 200 of manufacturing a frame element 113 for a touch sensitive device 100. The method 200 includes a step 201 of extruding the frame element 113 to form a light guide 108 and a cavity 125 adapted to receive a substrate 119 including an emitter 105 and / or a detector 106. FIG. 7a shows an example of such an extruded frame element 113. The method 200 further includes a step 202 of milling a wall 127 of the cavity 125 to form a channel 112. FIG. 7a shows in dashed lines the wall 127 to be milled away so as to provide an open channel 112 in the cavity 125 as illustrated in FIG. 7b. The channel 112 is defined by channel walls or surfaces 115a, 115b. The light guide surface 109 of the light guide 108 can receive light from the emitter 105 or guide light to the detector 106 via the channel 112 when the substrate 119 is placed in the cavity 125. Thus, a single integral part of the frame element 113 can be provided by the extrusion 201 and milling 202, incorporating the functions of alignment and support of the light guide surfaces 109, 115a, 115b as well as the substrate 119. Easy manufacturing is provided while the structural integrity and desired tolerances of the frame element 113 can be maintained during the process. Furthermore, the milling 202 can provide customization of the dimensions of the channel 112 that are difficult during the extrusion process.

[0046] FIG. 7c shows another example of an extruded frame element 113. The frame element 113 can be shaped such that the light guide surface 109 has an unobstructed line of sight 137, 137' to facilitate subsequent surface treatment of the light guide surface 109. The line of sight 137, 137' may run parallel to the normal (n) of the light guide surface 109. FIG. 7c shows an example where the line of sight of the light guide surface 109 is shown by a lower dashed line 137, which corresponds to the normal (n) of the surface 109, and an upper dashed line 137'. Having an unobstructed line of sight 137, 137' by the frame element 113, i.e. no obstruction or intersection of said line of sight 137, 137', allows optimizing subsequent surface treatment processes of the light guide surface 109, such as sandblasting. Thus, the desired properties of the light guide surface 109 can be easily obtained. The frame element 113 may include an inclined portion 138, as shown diagrammatically in Fig. 7c, which allows to obtain an unobstructed line of sight 137, 137' of the light guide surface 109 as described above, while maintaining a compact profile of the frame element 113. As shown in the example of Fig. 7c, the inclined portion 138 may be arranged such that the lower line of sight 137, which corresponds to the intersection of the normal (n) with the surface 109 (closest to the wall 127) at the lower end 139 of the surface 109, extends beyond the frame element 113 without intersecting the frame element 113 or the inclined portion 138. This allows easy access for surface treatment of the entire light guide surface 109, while maintaining a particularly compact frame element 113. The wall 127 may be part of the inclined portion 138.

[0047] 10b-10c are further flow charts of the method 200. The method 200 may include steps 2011, 2031 of etching or bead or sand blasting the light guide surface 109. Thus, the light guide surface 109 may be provided with different reflectance properties. In one example, as shown in FIG. 10b, the etching or bead or sand blasting 2011 of the light guide surface 109 is performed before the milling 202. Thus, different reflectance properties may be provided to the light guide surface 109 without affecting the surfaces 115a, 115b of the channels 112 that are blocked by the walls 127 during the sand blasting process, for example. As mentioned above, it may be advantageous to maintain the larger specular component of the walls 115a, 115b as provided after the extrusion process, whereas the light guide surface 109 may be subsequently treated to provide a more diffuse reflection. In some examples, as shown in Figure 10c, etching or bead or sand blasting 2031 of the light guiding surface 109 can be performed after milling 202. In some examples, as further shown in Figure 10c, etching or bead or sand blasting 2031 of the light guiding surface 109 can be performed after an additional milling step 203, described below. The method 200 can include anodizing 204 of the metal of the frame element 113, as described above.

[0048] The method 200 can include a step 203 of milling the apex 128 of the extruded light guide 108 such that the height (h) of the light guide 109 above the touch surface 102 of the panel 101 when placed on the frame element 113 is reduced. FIG. 8a shows a detailed view of an example of a light guide 108 after extrusion. The radius of the tip 130 of the apex 128 is limited by the extrusion process. FIG. 8b shows the light guide 108 after the apex 128 has been milled away along the dashed line in FIG. 8a. The milled light guide 108 has a height (h) and a corresponding tip 130' that is sharper, i.e., has a smaller radius, compared to the tip 130 provided after extrusion, as shown in FIG. 8b. Thus, by milling away the apex 128, a more compact light guide 108 is provided, while the portion of the light guide 108 useful for reflecting light across the touch surface 102 is essentially unaffected. The rounded tip 130 in FIG. 8a does not help guide light across the touch surface 102. For this reason, as shown in FIG. 8b, the rounded tip 130 has been removed. By milling the apex 128 in this manner, the height of the light guide 108 can be more effectively utilized. This can provide a sufficient height or height distribution of the scan line above the touch surface 102 to enable reliable identification of a variety of touch objects having a variety of tip sizes while minimizing the height of the bezel. In some examples, the height is in the range of 1.5-2 mm. A height of 1.8 mm can be particularly advantageous in some examples, providing the appearance of a flat bezel.

[0049] As shown diagrammatically in FIG. 8c, the light guiding surface 109 may be concave. Having the light guiding surface 109 concave towards the touch surface 102 allows for the direction of reflected light to be controlled and the signal strength of the scan line to be increased as required. The light guiding surface 109 may be parabolic concave. The light guiding surface 109 may be formed directly on the frame element 113 as described above, thus forming a concave shape directly on the frame element 113. In this way, the reflection of light may be controlled by directly shaping the frame element 113 without introducing additional optical components.

[0050] FIG. 8d is a schematic diagram showing details of the light guide surface 109 in different views I-III. The first view (I) is along the direction 103 of the plane 103, e.g., arrow 103 in FIG. 8c. Thus, the light guide surface 109 is illustrated as an elongated section, placed above the panel 101, with the emitter 105 and detector 106 located below the panel 101. FIG. 8d shows a detailed section of the light guide surface 109 in the second view (II). The light guide surface 109 may be milled or otherwise machined to form a pattern on the surface 109. The third view (III) of FIG. 8d is a cross section along AA in view (II), where an example of such a pattern is shown, with periodic ridges 136 forming a wave pattern or grating. Various patterns can be formed directly on the frame element 113 by milling or other machining processes to provide the light guide surface 109 with the desired reflective properties to control the direction of light across the touch surface 102.

[0051] Further examples of diffuse light scattering surfaces are described below. Any of the described diffuse light scattering surfaces can be provided on the light guide surface 109. The diffuse light scattering surface can be configured to exhibit at least 50% diffuse reflection, preferably at least 70-85% diffuse reflection. A reflectance at 940 nm of more than 70% can be achieved, for example for materials with a black appearance, by anodization as described above (e.g. electrolytic coloring with metal salts). The diffuse light scattering surface can be realized as a coating, layer or film, applied, for example, by anodization, painting, spraying, lamination, gluing, etc. Etching and blasting as described above are effective procedures to reach the desired diffuse reflectance. In one example, the diffuse light scattering surface is realized as a matte white paint or ink. To achieve a high diffuse reflectance, it may be preferred that the paint / ink contains a pigment with a high refractive index. One such pigment is TiO 2and has a refractive index n=2.8. The diffuse light scattering surface may include a material with a varying refractive index. It may also be desirable for the refractive index of the paint filler and / or paint vehicle to match the refractive index of the material on the surface to which it is applied, for example to reduce Fresnel losses. The properties of the paint may be further improved by using EVOQUE™ Pre-Composite Polymer Technology provided by Dow Chemical. Many other coating materials for use as diffusers are commercially available, such as fluoropolymer Spectralon, polyurethane enamel, barium sulfate-based paints or solutions, granular PTFE, microporous polyester, GORE® Diffuse Reflector Product, Makrofol® polycarbonate film provided by Bayer AG, etc. Alternatively, the diffuse light scattering surface may be realized as a flat or sheet-like device, such as the artificial diffuser described above, a diffuser film, or white paper attached, for example, by adhesive. According to another alternative, the diffuse light scattering surface can be realized as a semi-randomized (non-periodic) microstructure on the outer surface, possibly in combination with a coating on a reflective material.

[0052] Microstructures may be provided on such exterior and / or interior surfaces by etching, embossing, molding, abrasive blasting, scratching, brushing, etc. Diffuse light scattering surfaces may include pockets of air along such interior surfaces, which may be formed during a molding procedure. In another alternative, the diffuse light scattering surface may be light transmissive (e.g., a light transmissive diffusing material or a light transmissive artificial diffuser) with the exterior surface covered with a coating of a reflective material. Another example of a diffuse light scattering surface is a reflective coating provided on a rough surface.

[0053] The diffuse light scattering surface may include a lenticular lens or a diffraction grating structure. The lenticular lens structure may be incorporated into the film. The diffuse light scattering surface may include various periodic structures, such as sinusoidal corrugations, provided on the inner and / or outer surfaces. The length of the period may be in the range of 0.1 mm to 1 mm. The periodic structures may be aligned to achieve scattering in a desired direction.

[0054] Thus, as discussed above, the diffuse light scattering surface may include various artificial films such as white or colored paint, white or colored paper, Spectralon, light-transmitting diffusing materials covered with reflective materials, diffusing polymers or metals, artificial diffusers, reflective semi-random microstructures, in-mold air pockets or films of diffusing materials, such as lenticular lenses, or other microlens or lattice structures. The diffuse light scattering surface preferably has low NIR absorption.

[0055] In any of the above embodiments in which the diffuse light scattering element provides the reflective surface, the diffuse light scattering element has no or only a small specular component. This can be achieved by using either a matte diffusing film in air, an internally reflective bulk diffuser, or a bulk transmissive diffuser. This effectively widens the scan lines by avoiding the narrow overlapping specular scan lines that typically result from the diffuser interface with a specular component and providing only a wide and diffuse scan line profile. By removing the overlapping specular scan lines from the touch signal, the system can more easily use a wide and diffuse scan line profile. Preferably, the diffuse light scattering surface has a specular component of less than 1%, and more preferably less than 0.1%. Alternatively, if the specular component is greater than 0.1%, the diffuse light scattering element is preferably configured with surface roughness to reduce gloss, e.g., microstructured.

[0056] The panel 101 can be made of glass, poly(methyl methacrylate) (PMMA) or polycarbonate (PC). The panel 101 may be designed to overlap or be integrated with a display or monitor (not shown). The panel 101 does not need to be light-transmissive if the touch output does not need to be presented through the panel 101 and through the display device described above, but instead is displayed on another external display or communicated to any other device, processor, memory, etc. The panel 101 can include a shielding layer, such as a printed, i.e., ink cover, to block unwanted ambient light. This can reduce the amount of stray and ambient light reaching the detector 106.

[0057] Herein, the emitter 105 may be any type of device capable of emitting radiation in a desired wavelength range, such as, for example, a diode laser, a VCSEL (Vertical Cavity Surface Emitting Laser), an LED (Light Emitting Diode), an incandescent lamp, a halogen lamp, etc. The emitter 105 may also be formed by the end of an optical fiber. The emitter 105 may also generate light in any wavelength range. In the following examples, it is assumed that infrared (IR) light is generated, i.e. light with a wavelength above about 750 nm. Similarly, the detector 106 may be any device capable of converting light (in the same wavelength range) into an electrical signal, such as a photodetector, a CCD device, a CMOS device, etc.

[0058] In the context of the above discussion, "diffuse reflection" refers to the reflection of light from a surface such that incident light rays are reflected at many angles, not just one as in "specular reflection." Thus, a diffusely reflecting element, when illuminated, will emit light by reflection over a large solid angle at each location on the element. This diffuse reflection is also referred to as "scattering." While the above examples refer primarily to the elements discussed above in relation to emitter 105 for clarity of presentation, it should be understood that a corresponding arrangement may also be applied to detector 106.

[0059] The present invention has been described primarily with reference to certain embodiments, however, as will be readily understood by those skilled in the art, embodiments other than those described above are equally possible within the scope and spirit of the present invention, as defined and limited only by the appended claims.

[0060] For example, the specific arrangements of emitters and detectors discussed above are provided by way of example only, and the inventive combination is useful in any touch sensing system that operates by transmitting light generated by multiple emitters across a panel and detecting changes in received light caused by interaction with the transmitted light at the point of touch with multiple detectors.

Claims

1. A touch sensing device (100), a panel (101) defining a touch surface (102) extending in a plane (103) having a normal axis (104); a plurality of emitters (105) and detectors (106) disposed along a periphery (107) of the panel; a light guide portion (108) disposed adjacent the outer periphery and including a light guide surface (109); The emitter is arranged to emit light (110), and the light directing surface is arranged to receive and direct the light across the touch surface; the panel having a back surface (111) opposite the touch surface; The emitter and / or the detector are arranged opposite the rear surface to emit and / or receive light through a channel (112) in a frame element (113), the channel being arranged opposite the rear surface and extending in the direction of the normal axis (104'); the light guide surface and the channel are disposed on opposite sides of the panel and overlap in the direction of the plane; the light guide surface receives light from the emitter or guides light to the detector through the panel and the channel in the direction of the normal axis; the frame element includes the light guide, the frame element being made of metal; 11. The touch sensing device, wherein the light guiding surface is an anodized metal surface of the frame element, and / or an etched, sandblasted, bead blasted, or brushed metal surface of the frame element.

2. The touch sensing device according to claim 1 , the panel having an edge (114) extending between the touch surface and the back surface; The channels have a width (d) between a first channel wall (115a) located closest to each edge (114) of the panel and an opposing second channel wall (115b). １ ) extending in a direction parallel to said plane; The touch sensitive device, wherein the first channel wall extends at an angle (116) with respect to the normal axial direction (104').

3. The touch detection device according to claim 1 or 2, 11. A touch sensing device comprising: a light guide surface (109) extending from an edge portion (121) of the light guide located closest to the touch surface to a protrusion (117) of the light guide, the protrusion extending in a direction parallel to the plane to block ambient or stray light from being reflected towards the channel.

4. The touch detection device according to any one of claims 1 to 3, A touch sensing device, characterized in that the emitters and / or detectors are attached to a substrate (119), the substrate including a chamfered edge (120a) positioned opposite a corresponding engagement surface (120b) of the frame element, the engagement surface being angled (122) with respect to the normal axis.

5. The touch detection device according to any one of claims 1 to 4, A touch sensitive device, characterized in that the walls (115a, 115b) of the channel comprise a diffuse light scattering surface.

6. The touch detection device according to any one of claims 1 to 5, the panel having an edge (114) extending between the touch surface and the back surface; The frame element defines a cavity (125); The touch sensing device, characterized in that the emitters and / or detectors are attached to a substrate (119) and the substrate is positioned within the cavity such that the emitters and / or detectors are positioned closer to respective edges of the panel than the substrate.

7. The touch sensing device according to claim 1 , A touch sensitive device, characterized in that the frame element forms a cavity (125) in which the emitters and / or detectors are located.

8. The touch detection device according to any one of claims 1 to 7, A touch sensitive device, wherein the light guide surface (109) has a surface roughness defined by a slope RMS (Δq) of 0 to 0.

25.

9. The touch sensing device according to claim 8, A touch sensitive device, wherein the light guide surface (109) has a surface roughness defined by a slope RMS (Δq) of 0.13 to 0.

20.

10. The touch detection device according to any one of claims 1 to 9, The touch sensitive device, wherein the light guide includes an exterior surface (126) opposite the light guide surface, the light guide surface having a higher reflectivity than the exterior surface.

11. The touch detection device according to any one of claims 1 to 10, A touch sensitive device, characterized in that the walls (115a, 115b) of the channel have a higher specular reflectance than the light guide surface.

12. A method (200) for manufacturing a frame element (113) for a touch sensitive device (100), comprising the steps of: - extruding (201) said frame element to form a light guide (108) and a cavity (125) adapted to receive a substrate (119) with an emitter (105) and / or detector (106); and milling (202) a wall (127) of the cavity to form a channel (104) extending in a direction of a normal axis (104) such that, in use, a light guide surface (109) of the light guide receives light from the emitter or directs light to the detector via a channel (112) extending in the direction of the normal axis (104), the normal axis extending perpendicular to a plane (103) of the panel (101) when the panel defining a touch surface (102) of the touch sensitive device is positioned between the light guide and the emitter and / or the detector.

13. 13. The method of claim 12, The method comprising the step (2011) of etching, or bead blasting or sand blasting the light guiding surface.

14. 14. The method according to claim 12 or 13, milling (203) a top portion (128) of the extruded light guide such that when placed on the frame element, a height (h) of the light guide above a touch surface (102) of a panel (101) is reduced.

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