Optical system

Abstract

A touch sensitive device comprising: a top plate having a plurality of light sources associated therewith such that light from the plurality of light sources is transmitted within the top plate in a total internal reflection manner; and a substrate having one or more detectors associated therewith, the detectors for detecting light transmitted within the substrate. The top plate and the substrate are configured such that if an external body touches a first surface of the top plate, light is coupled into the substrate from a second surface of the top plate through a first surface of the substrate. The plurality of light sources are disposed within a linearly extending recess in a second surface of the top plate such that light from the plurality of light sources is coupled into the top plate through walls of the recess. The plurality of light sources form a linear array within the linearly extending recess.

Description

TECHNICAL FIELD

[0001] The present invention relates to an optical system suitable for use in a touch sensitive device. Embodiments are particularly suitable for use in the controller of an electronic, human-machine interface (HDI), such as a car central console, a washing machine panel, a hand-held game controller or other suitable smart controller HDI. BACKGROUND

[0002] Currently, in a typical optical touch screen, light is emitted from light emitting diode (LED) emitters through the peripheral edge of the plate, which can be convenient to implement, but can result in inefficient optical illumination of particular touch sensitive areas. This is typically caused by a reduction in power of the light as it travels a long distance through the light guide, or by the light not being directed where it is most needed. This optical inefficiency results in the use of more LED emitters than can be needed, and results in higher electrical power consumption, which is detrimental in systems where electrical power management is critical.

[0003] It is an object of the present invention to address one or more of the disadvantages associated with the prior art, and to provide an improved touch screen in terms of cost and reliability. SUMMARY

[0004] In another aspect, there is provided a touch sensitive device comprising: a top plate having associated therewith a plurality of light sources, such that light from the plurality of light sources is transmitted within the top plate in a total internal reflection manner; and a base plate having associated therewith one or more detectors for detecting light transmitted within the base plate. The top plate and base plate are configured such that if an external body touches a first surface of the top plate, light is coupled from a second surface of the top plate into the base plate through a first surface of the base plate. The plurality of light sources are disposed within a linearly extending recess in the second surface of the top plate, such that light from the plurality of light sources is coupled into the top plate through a wall of the recess. The plurality of light sources form a linear array within the linearly extending recess.

[0005] Having a recess that linearly extends along the second surface of the top plate, i.e. effectively forming a trench in the second surface, allows the light sources to be mounted such that light can be easily directly shot into the bulk of the top plate. This allows light to be uniformly and highly efficiently shot into the top plate.

[0006] The linearly extending recess can extend as a straight line, or it can be curved. Similarly, the linear array of light sources can be a straight or curved line.

[0007] The wall of the recess can form an angle with the plane of the top plate, such that the wall and the second surface of the top plate form an obtuse angle within the top plate.

[0008] The mounting of the light sources relative to the wall of the refracting face or each refracting face can be such that the refracted light thereby increases evanescent field strength while containing the light within the roof by total internal reflection.

[0009] The wall of the recess can be lenticular.

[0010] Each of the plurality of light sources can be mounted at an angle to the plane of the roof such that light emitted from the light source is primarily obliquely directed towards the first surface.

[0011] Each of the plurality of light sources can be mounted such that light emitted from the light source is primarily obliquely directed towards the wall of the recess.

[0012] The mounting of the light sources at an angle to the wall of the recess in this way can be used to increase or otherwise adjust the evanescent field strength, thereby maximising or tuning the responsiveness of the device to touch.

[0013] The roof can further comprise a width-reducing section in which the distance between the first surface and the second surface is substantially constant but less than the distance between the first surface and the second surface at the recess.

[0014] While some embodiments of the invention have a roof of substantially uniform thickness, not including a recess, other arrangements are possible and can provide enhanced possibilities for controlling the total internal reflected light.

[0015] The roof can further comprise a ramp section in which the distance between the first surface and the second surface of the roof is reduced, the ramp section being located between the recess and the width-reducing section.

[0016] The ramp section can taper linearly. The ramp section can taper non-linearly.

[0017] An area of the first surface can be masked to prevent total internal reflection of light from the plurality of light sources in the trench.

[0018] Masking can be provided for a section of the first surface that is located on the recess and extends beyond the recess to limit the angular range of incident light from the plurality of light sources that is reflected at the first surface.

[0019] Masking can be provided by a light-absorbing layer provided on or at the first surface.

[0020] An area of the recess between the light source and the first surface can be masked.

[0021] Masking can be provided by a light-absorbing layer provided on or at the surface of the recess.

[0022] Masking can be provided by a light-absorbing element mounted with the light source.

[0023] The masking of the recessed regions defines apertures for the emission of light from the light sources into the top plate.

[0024] Masking in this way increases the proportion of light from each light source that is constrained within the top plate by total internal reflection. In embodiments, substantially all of the light that is not absorbed by the masking and enters the top plate is constrained within the top plate by total internal reflection. Thus, by using the masking, the proportion of light that is constrained within the top plate relative to the light that is allowed to enter the system to reflect at the first and second surfaces is increased. In this way, stray light from the top plate is advantageously reduced.

[0025] The top plate can have a linear protrusion extending on the second surface away from the first surface, wherein the linear extension of the linear protrusion is substantially parallel to the linear extension of the groove. The linear protrusion can have a rectangular or sector-shaped cross-section perpendicular to its linear extent.

[0026] In some embodiments, there can be an air gap between the top plate and the substrate. In other embodiments, there can be a layer of optically transmissive material between the top plate and the substrate.

[0027] The plurality of light sources can be spaced apart to form a substantially uniform light distribution in the body of the top plate. Each of the plurality of light sources can be a light emitting diode. Each light emitting diode can emit light in the near infrared range.

[0028] The walls of the recess can be configured to limit the vertical angular extent of light propagating in the top plate from the plurality of light sources. The walls of the recess can be configured or arranged to reduce the vertical angular extent of light incident on the walls. Limiting the vertical angular extent of light propagating within the top plate can increase the proportion of light that is constrained within the top plate by total internal reflection, and correspondingly reduce the proportion of light that is released from the top plate as stray light.

[0029] The walls of the recess can be configured to increase the horizontal angular extent of light incident on the walls of the recess. In this way, the horizontal angular extent of light from the light sources within the top plate can be greater than the horizontal angular extent of light from the light sources prior to being incident on the walls of the recess. In this way, the walls of the recess can diffuse the incident light in the horizontal dimension within the top plate. This provides for a more uniform distribution of light on the top plate for touch responsiveness. Furthermore, this control of the horizontal diffusion of light in the top plate improves the uniformity of light closer to the light sources, enabling the creation of an actual active area that can sense touches closer to the light sources.

[0030] The emission area of the light source can be positioned at a predetermined distance from the wall of the recess so as to limit the range of vertical angles of light rays from the light source that propagate in the top plate. In embodiments, the position of the light source and its emission area relative to the wall of the recess can be chosen so that only a fraction of the light rays from the light source are captured and coupled into the top plate by the wall of the recess. In this way, the range of vertical angles of light from the light source that is allowed to propagate in the top plate can be limited so that substantially all light from the light source that enters the top plate is subsequently constrained by total internal reflection, thereby reducing stray light from the system.

[0031] The range of vertical angles of light rays from the light source that propagate in the top plate can be limited so that substantially all light from the light source that is coupled into the top plate is constrained in the top plate by total internal reflection.

[0032] It will be appreciated that the touch sensitive device can be configured to not increase the total amount of light coupled into the top plate, but rather to increase the proportion of light coupled into the top plate that is constrained within the top plate by total internal reflection. In other words, it can be an object of the present invention to ensure that substantially all light coupled into the top plate experiences total internal reflection at the first and second surfaces, thereby being constrained within the top plate. In contrast to prior art systems that prioritize maximizing the amount of light coupled into the plate or waveguide, the present invention maximizes the proportion of that light that is constrained within the waveguide after being coupled into the waveguide.

[0033] One or more of the angle of the wall of the recess to the plane of the top plate, the mounting of the light source relative to the wall of the recess, and the curvature of the wall of the recess can be configured to limit the range of vertical angles of light from the light source that propagate within the top plate, thereby increasing the evanescent field intensity at the first surface while constraining the light within the top plate by total internal reflection.

[0034] Limiting and controlling the range of vertical angles allows the system to be optimized to increase the evanescent field intensity at the first surface while still constraining the light within the top plate by total internal reflection. The mounting of the light source can define the distance of the emission area of the light source from the wall of the recess and / or can (at least partially) determine the angle at which light from the light source is incident on the wall of the recess.

[0035] The perimeter of the recess on the second surface can be entirely contained within the second surface.

[0036] In addition to the main aspects of the present invention as described above, embodiments of the present invention also illustrate the following secondary aspects. The main aspects of the present invention as described above can be combined with the following secondary aspects or individual features of the following secondary aspects to provide further aspects of the present invention.

[0037] In another aspect, a touch sensitive device is provided, comprising: a top plate having one or more light sources associated therewith such that light from the one or more light sources is transmitted within the top plate in a total internal reflection manner; and a base plate having one or more detectors associated therewith for detecting light transmitted within the base plate. The top plate and base plate are configured such that if an external body touches a first surface of the top plate, light is coupled from a second surface of the top plate into the base plate through a first surface of the base plate. Each of the one or more light sources is disposed in a recess within the top plate for that light source, wherein the recess has one or more refractive input faces such that light from the light source is coupled into the body of the top plate through the one or more refractive input faces.

[0038] For one or more light sources, the recess can have a central refractive input face and two side refractive faces disposed symmetrically around and adjacent to the central refractive input face.

[0039] The central refractive input face can have a different curvature than the side refractive faces. In some embodiments, the central refractive input face can have a conic curvature. In some embodiments, the central refractive input face can have an elliptical curvature.

[0040] The wall of the refractive input face or each refractive input face can form an angle with the plane of the top plate such that the refractive input face and the second surface of the top plate form an obtuse angle within the top plate.

[0041] The mounting of the light source relative to the wall of the refractive input face or each refractive input face can be such that the evanescent field strength is thereby increased while light is confined within the top plate by total internal reflection.

[0042] The wall of the refractive input face or each refractive input face can be lenticular.

[0043] The light source or each light source can be mounted at an angle to the plane of the top plate such that light emitted from the light source is primarily obliquely directed towards the first surface.

[0044] Each light source can be mounted such that light emitted from the light source is primarily obliquely directed towards at least one refractive input face.

[0045] The mounting of the light source at an angle relative to the wall of the recess in this manner can be used to increase or otherwise adjust the evanescent field strength, thereby maximizing or tuning the responsiveness of the device to touch.

[0046] The top plate can also include a reduced width section in which the distance between the first surface and the second surface is substantially constant but less than the distance between the first surface and the second surface at the recess. The top plate can also include a ramp section in which the distance between the first surface and the second surface of the top plate decreases, the ramp section being located between the recess and the reduced width section.

[0047] The ramp section can taper linearly. The ramp section can taper non-linearly.

[0048] In some embodiments, there can be an air gap between the top plate and the substrate. In other embodiments, there can be a layer of optically transmissive material between the top plate and the substrate.

[0049] An area of the first surface can be masked to prevent total internal reflection of light from each light source in the recess. The masking can be provided for a section of the first surface that is over the recess and extends beyond the recess to limit the range of angles of incident light from the plurality of light sources that is reflected at the first surface. The masking can be provided by a light absorbing layer provided on or at the first surface.

[0050] The touch sensitive device can include a plurality of light sources. The masking can extend over two or more light sources of the plurality of light sources.

[0051] The masking can define an active area of the top plate in which the plurality of light sources illuminate the active area of the top plate.

[0052] The plurality of light sources can be disposed around a perimeter of the active area. The perimeter of the active area can be rectangular. The perimeter of the active area can be elliptical.

[0053] The first surface of the top plate in the active area can not be planar.

[0054] The plurality of light sources can be spaced apart to form a substantially uniform light distribution in the active area of the top plate.

[0055] An area of each recess between the light source and the first surface can be masked. The masking can be provided by a light absorbing layer provided on or at a surface of the recess.

[0056] The masking can also be provided by a light absorbing element mounted with the light source.

[0057] The masking of the area of the recess can define an aperture for emitting light from the light source into the top plate.

[0058] Each of the one or more light sources can be a light emitting diode. Each of the one or more light emitting diodes can emit light in the near infrared range.

[0059] In another aspect, there is provided a touch sensitive device comprising: a top plate having one or more light sources associated therewith such that light from the one or more light sources is transmitted within the top plate in a total internal reflection manner; and a substrate having one or more detectors associated therewith for detecting light transmitted within the substrate. The top plate and the substrate are configured such that if an external body touches a first surface of the top plate, light is coupled from a second surface of the top plate into the substrate through a first surface of the substrate. The device is configured such that a horizontal angular range of light from each of the one or more light sources increases upon entry into the top plate through an entry face of the top plate. An emission area of each light source is positioned at a predetermined distance from the entry face so as to limit a vertical angular range of light rays propagating in the top plate from the light source.

[0060] In another aspect, there is provided a touch sensitive device comprising: a top plate having one or more light sources associated therewith such that light from the one or more light sources is transmitted within the top plate in a total internal reflection manner; and a substrate having one or more detectors associated therewith for detecting light transmitted within the substrate. The top plate and the substrate are configured such that if an external body touches a first surface of the top plate, light is coupled from a second surface of the top plate into the substrate through a first surface of the substrate. One or more regions of the first surface, the second surface, or both the first surface and the second surface are provided with a layer that suppresses internal reflection at that region of the surface, thereby providing optical separation between a portion of the top plate and another portion of the top plate.

[0061] The layer can be an absorbing layer.

[0062] The top plate can be formed by molding and the layer can be formed by overmolding or in-mold labeling.

[0063] The layer can separate at least one active region from other regions of the first surface, wherein each active region is isolated from any other optical activity in the top plate. An active region can provide a single touch sensitive device functionality.

[0064] The touch sensitive device functionality can comprise one of a dial, a slider, a button, a trigger, and a touchscreen.

[0065] Each of the one or more light sources is disposed within the top plate in a recess for that light source. The recess can have one or more refractive input faces such that light from the light source is coupled into a body of the top plate through the one or more refractive input faces.

[0066] A wall of the or each refractive input face can form an angle with a plane of the top plate such that the refractive input face and a second surface of the top plate form an obtuse angle within the top plate.

[0067] The wall of the or each refractive input face can be lenticular.

[0068] Each light source can be mounted at an angle to the plane of the top plate such that light emitted from the light source is primarily directed obliquely towards the first surface.

[0069] Each light source can be mounted such that light emitted from the light source is primarily directed obliquely towards the at least one refractive input face.

[0070] The plurality of light sources can be disposed around a perimeter of the active area. The perimeter of the active area can be rectangular. The perimeter of the active area can be elliptical.

[0071] The first surface of the top plate in the active area can not be planar.

[0072] The plurality of light sources can be spaced apart to form a substantially uniform light distribution in the active area of the top plate. There can be a plurality of active areas separated by the layer.

[0073] Two of the plurality of active areas can have different touch sensitive device functionality. Two of the plurality of active areas can have different optical properties. Two of the plurality of active areas can have light sources of different properties. Two of the plurality of active areas can be associated with regions of the substrate having different optical properties.

[0074] The touch sensitive device can further comprise an absorbing layer at a portion or all of the periphery of the top plate.

[0075] Each of the one or more light sources can be a light emitting diode.

[0076] In some embodiments, the light sources can emit in the near infrared range and the absorbing layer can absorb in the near infrared range. One or more regions of the first surface can be provided with an additional layer. The additional layer can absorb in the visible spectral range. The additional layer can at least partially cover the absorbing layer.

[0077] In another aspect, a method of manufacturing an optical light transmissive sheet is provided. The method comprises: forming the optical light transmissive sheet into a laminate, wherein the optical light transmissive sheet is adapted for total internal reflection to occur at a first face and a second face of the optical light transmissive sheet; and forming one or more light absorbing layer regions on the first face, the second face, or both the first face and the second face of the optical light transmissive sheet, wherein the one or more light absorbing layer regions are formed during the forming.

[0078] The light absorbing layer regions can be formed by in-mould labelling.

[0079] The light absorbing layer regions can encompass a first region that absorbs light in the near infrared region. The light absorbing layer regions can include a second region that absorbs light in the visible region.

[0080] In another aspect, there is provided a method of manufacturing an optical element for a touch screen device, the method comprising: forming an optical light sheet by the method of any of the preceding paragraphs; laminating the optical light sheet with an intermediate optical layer and a further optical light sheet, wherein the intermediate optical layer has a lower refractive index than the optical light sheet.

[0081] The intermediate optical layer can provide optical bonding between the optical light sheets. The intermediate optical layer can comprise a fluorinated ethylene propylene.

[0082] The optical element can be formed by overmolding.

[0083] In another aspect, there is provided a method of manufacturing a touch screen device, the method comprising: manufacturing an optical light sheet as described in any of the preceding paragraphs as a top plate, and mounting the top plate in the touch screen device, wherein a plurality of light sources are mounted in association such that light from the plurality of light sources is transmitted within the top plate in a total internal reflection manner; and mounting a substrate relative to the top plate such that if an external body touches a first surface of the top plate, light is coupled into the substrate from a second surface of the top plate through a first surface of the substrate, and mounting one or more detectors in association with the substrate, the detectors being for detecting light transmitted within the substrate.

[0084] The top plate and the substrate can be mounted with an air gap therebetween. In such embodiments, the air gap can be provided by a foam mask spacer.

[0085] The optical light sheet can be manufactured by the method of forming the optical light sheet of any of the preceding paragraphs; wherein the optical light sheet is laminated with an intermediate optical layer and a further optical light sheet, wherein the intermediate optical layer has a lower refractive index than the optical light sheet, and wherein the substrate is the further optical light sheet.

[0086] The substrate can be mounted above a display configured to emit light from the touch screen device through the top plate.

[0087] The light absorbing layer can absorb light emitted by the light sources, and can be adapted to mask the light sources. Masking of the light sources can substantially limit propagation of light from the light sources through the top plate, such that substantially only light directed for total internal reflection at a surface of the top plate can propagate.

[0088] The light sources can emit in the near infrared range, and the light absorbing layer regions can absorb in the near infrared range.

[0089] The substrate can be a weak absorber of light emitted from the plurality of light sources. The substrate can be chemically doped with a weakly absorbing material.

[0090] The top plate can extend beyond the substrate. The one or more light sources can be mounted in a region of the top plate that extends beyond the substrate.

[0091] The top plate can be tapered from a thicker region where the one or more light sources are mounted to a thinner region where the top plate is disposed on the substrate.

[0092] The one or more light sources can be mounted in one or more recesses in a second surface of the top plate and can be disposed to transmit light into the top plate through a wall of the recess in which the light source is disposed.

[0093] The recesses can be linearly extending recesses and the plurality of light sources can be mounted in the recesses in a linear array.

[0094] In some embodiments, the linearly extending recesses and the linear array can extend along a straight line. In other embodiments, the linearly extending recesses and the linear array can extend along a curve.

[0095] One or more recesses can be formed for each of the one or more light sources. Each recess can have one or more refractive input faces such that light from the light source is coupled into the body of the top plate through the one or more refractive input faces.

[0096] The substrate can be mounted to prevent light that emanates from the substrate and is not received by the one or more detectors from entering the top plate.

[0097] In another aspect, a packaged light emitting diode is provided that includes a light emitting diode die and a cylindrical lens mounted directly on a light emitting surface of the light emitting diode die, whereby light emitted through the cylindrical lens has a narrow angular distribution along a first axis and a wide angular distribution along a second axis that is orthogonal to the first axis.

[0098] The cylindrical lens can be formed as a truncated substantially oblate spheroid lens in a body having two first truncations and one second truncation. The two first truncations can be perpendicular to an axis of the oblate spheroid and equidistant from a longest radius of the oblate spheroid and can be parallel to two axes of the oblate spheroid and parallel to each other. The second truncation can be parallel to the other axis of the oblate spheroid and perpendicular to the two first truncations. The light emitting diode die can be adjacent to the second truncation.

[0099] The cylindrical lens can be a spheroid.

[0100] The cylindrical lens can be formed as an aspherical lens in a modified ellipsoid having two first truncations and one second truncation. The two first truncations can be perpendicular to an axis of the modified ellipsoid and equidistant from a longest radius of the modified ellipsoid, and can be parallel to two axes of the oblate ellipsoid and parallel to each other. The second truncation can be parallel to another axis of the oblate ellipsoid and perpendicular to the two first truncations.

[0101] The light emitting diode die can be adjacent to the second truncation. The ellipsoid can be modified to have a greater curvature in a direction perpendicular to a light emitting surface of the light emitting diode die than the ellipsoid, and a smaller curvature in a direction parallel to the light emitting surface of the light emitting diode die than the ellipsoid.

[0102] A length of the two first truncations perpendicular to the light emitting surface of the light emitting diode die can be greater than half a length of the lens body perpendicular to the light emitting surface of the light emitting diode die.

[0103] In another aspect, a touch sensitive device is provided that includes a top plate having one or more light sources associated therewith such that light from the one or more light sources is transmitted within the top plate in a total internal reflection manner, and a substrate having one or more detectors associated therewith for detecting light transmitted within the substrate. The top plate and substrate are configured such that if an external body touches a first surface of the top plate, light is coupled from a second surface of the top plate into the substrate through a first surface of the substrate. Each of the one or more light sources is disposed within the top plate in a recess for that light source, wherein the recess has a refractive input face such that light from the light source is coupled into a body of the top plate through the refractive input face, and wherein each of the one or more light sources is a packaged light emitting diode as described in the paragraphs above.

[0104] The mounting of each of the one or more light sources relative to the refractive input face can be such that a combination of a lens of the light source and a shape of the refractive input face is suitable for diffusing light substantially uniformly in a plane of the top plate.

[0105] A wall of the or each refractive input face can form an angle with a plane of the top plate such that the refractive input face and the second surface of the top plate form an obtuse angle within the top plate.

[0106] Each of the light sources can be mounted at an angle to a plane of the top plate such that light emitted from the or each light source is primarily obliquely directed towards the first surface.

[0107] Each of the light sources can be mounted such that light emitted from the light source is obliquely directed towards the refractive input face.

[0108] The above methods, features, and aspects can be used alone or in combination. Features of one aspect can be applied to features of another aspect, alone or in appropriate combination. BRIEF DESCRIPTION OF DRAWINGS

[0109] In order that the application can be more readily understood, preferred non-limiting embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic cross-sectional view of a touch screen device; Figure 2 shows a touch screen device incorporated in a cab of a vehicle; Figure 3 is a cross-sectional view of a portion of a light guide incorporating a light source disposed in a recess in the lower side of the light guide; Figure 4 is a cross-sectional view of a portion of another light guide incorporating a light source disposed in a recess in the lower side of the light guide; Figure 5 is a perspective view of a portion of a light guide incorporating a trench injection optic geometry and including a ramped section; Figure 6 is a perspective view of a portion of another light guide incorporating a trench injection optic geometry and having a constant thickness; Figure 7 is a perspective view of a portion of a light guide incorporating a pocket injection optic; Figure 8a shows a range of angles of light rays that exceed the critical angle at the boundary between an acrylic material and air; Figure 8b shows a range of angles of light rays that exceed the critical angle at the boundary between an acrylic material and FEP; Figure 9 is a cross-sectional view of a portion of a light guide incorporating a light source disposed in a recess in the lower side of the light guide; Figure 10 is a cross-sectional view of a portion of another light guide incorporating a light source disposed in a recess in the lower side of the light guide, with an absorption mask disposed at the upper surface of the light guide; Figure 11 is a perspective side view of a portion of a light guide incorporating a recess for receiving a light source in use, with the recess having a front wall with a lens; Figure 12a is a graph showing light lost from a light guide, with light injected into the light guide from a light source disposed in a recess in the lower side of the light guide, and power density coupled into and in the light guide, all for different angles of inclination of the front wall of the recess; Figure 12b is a cross-sectional view of a portion of a light guide incorporating a light source disposed in a recess in the underside of the light guide, wherein the front wall of the recess has no tilt; Figure 12c is a cross-sectional view of a portion of a light guide incorporating a light source disposed in a recess in the underside of the light guide, wherein the front wall of the recess has a tilt angle of 50°; Figure 13a is a graph showing light lost from a light guide, wherein light is launched into the light guide from a light source disposed in a recess in the underside of the light guide, the graph also showing light coupled into the light guide and power density in the light guide, all for different tilt angles of the front wall of the recess; Figure 13b is a cross-sectional view of a portion of a light guide incorporating a light source disposed in a recess in the underside of the light guide, wherein the front wall of the light source cavity has no tilt and the light source has no tilt; Figure 13c is a cross-sectional view of a portion of a light guide incorporating a light source disposed in a recess in the underside of the light guide, wherein the front wall of the light source cavity has a tilt angle of 30° and the central axis of the light source is approximately perpendicular to the front wall of the recess; Figure 14 is a perspective side view of a portion of a light guide incorporating a recess for receiving a light source in use, wherein the light guide includes an extruded section or trench adjacent the front wall of the recess; Figure 15 is a perspective side view of a portion of another light guide incorporating a recess for receiving a light source in use, wherein the light guide includes a non-linear ramp section; Figure 16 is a touch screen device incorporating a rectangular screen with sliders, a D-pad, and a protrusion; Figure 17a is a schematic perspective view of a portion of a trench launch optical device having a front wall that is straight and linearly extending; Figure 17b is a schematic perspective view of a portion of a trench launch optical device having a front wall that is curved and linearly extending; Figure 18a is a schematic perspective view of a pocket launch optical device, wherein the height and slope of the front wall of the recess varies with respect to its length; Figure 18b is a schematic perspective view of a pocket launch optical device incorporated in a light guide having a ramp section; Figure 19 is a schematic perspective view of a light guide incorporating a plurality of pocket launch optical devices, and including an absorbing mask layer on its upper surface; Figure 20 is a top view of a light guide incorporating a pocket launch optical device; Figure 21a is a side view of a portion of a light guide incorporating a light source disposed in a recess in the underside of the light guide; Figure 21b shows the intensity distribution of the output of the light source of the device of Figure 21a ; Figure 21c shows the intensity distribution of the light from the light source within the light guide of Figure 21a ; Figure 22a shows the horizontal and vertical intensity distributions of light from a wide-angle surface mount LED; Figure 22b shows the horizontal and vertical intensity distributions of light from a narrow-angle surface mount LED; Figure 23a is a perspective view of an LED device incorporating a circular lens; Figure 23b shows the horizontal and vertical intensity distributions of light from the device of Figure 23a ; Figure 24a is a perspective view of a hyper-elliptical LED package incorporating a cylindrical lens; Figure 24b shows the horizontal and vertical intensity distributions of light from the device of Figure 24a ; Figure 24c is a plan view of an LED package of Figure 24a ; Figure 25a is a side view of a portion of a light guide incorporating an LED package of Figure 24a ; Figure 25b is a perspective view of a portion of a light guide incorporating an LED package of Figure 24a ; Figure 25c shows the intensity distribution of the output of the LED package of Figure 24a , alone; Figure 25d shows the intensity distribution of the light from the light source within the light guide of Figure 25b ; Figure 26 is a graph showing the uniformity of the light intensity distribution in the light guide as a function of the distance in the z-direction from the pocket launch optic; Figure 27 is a graph showing the light power from an LED and the horizontal and vertical beam half-angles of the LED as a function of different LED chip sizes; Figure 28 is a perspective view of a light guide having a curved profile and incorporating sixteen pocket launch optics; FIG. 29a is another perspective view of the light guide of Figure 28 and showing light distribution in the light guide; FIG. 29b is a perspective view of a curved light guide incorporating twelve pocket-injection optics and showing light distribution in the light guide; Figure 29c is a perspective view of a curved light guide incorporating eight pocket-injection optics and showing light distribution in the light guide; Figure 29d is a graph showing uniformity of light power density in the sidewall of each of the light guides of FIGS. 29a to Figure 29c Figure 30 is a perspective view of a light guide having a rectangular profile and incorporating thirty-two pocket-injection optics; Figure 31a is another perspective view of the light guide of Figure 30 and showing light distribution in the light guide; Figure 31b is a perspective view of a rectangular light guide incorporating twenty-six pocket-injection optics and showing light distribution in the light guide; Figure 31c is a perspective view of a rectangular light guide incorporating twenty pocket-injection optics and showing light distribution in the light guide; Figure 31d is a graph showing uniformity of light power density in the x-axis of each of the light guides of Figures 31a to 31c Figure 32 is a perspective view of a curved light guide incorporating an active region and an inactive region; Figure 33 is a perspective view of a flat light guide including multiple active regions separated by an inactive region defined by an absorption mask layer; Figure 34a is a cross-sectional side view of a curved light guide incorporating an injection optic and an absorber on an end face disposed at either end; Figure 34b is a cross-sectional side view of a curved light guide incorporating an injection optic disposed at either end and an absorber along an end wall; Figure 35a is a cross-sectional side view of a curved light guide incorporating an injection optic disposed at either end and showing stray light reflected from one of the injection optics; Figure 35b is a cross-sectional side view of a curved light guide incorporating an injection optic disposed at either end and an absorber extending over one of the injection optics; Figure 36 ​​This is a cross-sectional side view of the part of the touch-sensitive device made of composite material; Figure 37 This is a cross-sectional side view of a portion of another touch-sensitive device made of composite material; Figure 38 This is a cross-sectional side view of a portion of another touch-sensitive device formed of laminated material; Figure 39 This is a cross-sectional side view of a portion of another touch-sensitive device formed of laminated material; Figure 40 A curved optical guide is shown, along with the radius of curvature and thickness of the optical guide used to calculate the turntable angle curvature ratio. Figure 41a This illustrates a pocket-type optics device that provides a narrow light distribution; Figure 41b This illustrates a pocket-type optics device that provides a wide light distribution in a curved light guide; Figure 42a Another example of an HE-LED package incorporating an aspherical lens is shown; Figure 42b Shown from Figure 42a The horizontal and vertical intensity distribution of light from the device; Figure 42c yes Figure 42a A plan view of the HE-LED package; Figure 43 This shows an intermediate layer formed by multiple sublayers, used as the middle layer in a laminated material. Detailed Implementation

[0110] Optical touch-sensitive light guides, primarily marketed as whiteboard upgrades and using flat light guides, are known. However, the market is moving in new directions, requiring the introduction of thin, continuous 3D curved upper layers to provide a single, free-flowing shape (without any mechanical components breaking through the surface), thus allowing for a more refined and aesthetically pleasing style. Security is also a key factor, necessitating the addition of geometric notches or grooves on the top surface of the upper layer to: (a) assist in finger positioning or guidance, and (b) allow users to identify relevant portions of the touchscreen simply by touch, without having to look at where their fingers are (i.e., “keeping your eyes on the road”).

[0111] According to the present invention, an optical touch-sensitive controller for an electronic human-machine interface (HDI) 8 is described.

[0112] The device of the present invention can utilize, for example, touchscreen technology developed by the applicant and described in WO2015 / 155508. In the method taught in WO2015 / 155508, suppressed total internal reflection is used in conjunction with a lossy substrate 18. The processing device can then determine the location of a touch using the transmission loss between light entering the substrate unit 18 and one or more detectors 20 associated with the substrate 18. This lossy substrate 18 can be a weak absorber of light emitted from a relevant light source and can be chemically doped with a weakly absorbing material for this purpose.

[0113] refer to Figure 1 It illustrates the method taught in WO2015 / 155508, whereby HDI 8 includes a three-layer optical laminate over one or more displays. Figure 1 (Not shown in the image). Light is coupled to the top plate or upper layer 10 of the laminate via total internal reflection and contained within the upper light guide 10 until a touch of the first or upper surface 23 of the upper layer 10 causes a small percentage of the light contained in the upper layer 10 to be emitted from the second or lower surface 25 of the upper layer 10 through the middle layer 14 (air or a low-refractive-index material) toward and through the first or upper surface 26 of the lower laminate 18 (i.e., substrate 18), where the light can be detected and the finger press position on the upper surface 23 can be determined. The lower laminate 18 is doped, and the light is dispersed in the lower laminate 18, so that the finger press position can be calculated based on the light detected at the photodetector 20. Multiple photodetectors 20 may be present and arranged around the lower laminate 18, which can be arranged to most effectively detect the finger press position of the geometry of the HDI 8.

[0114] It has now been discovered that a particularly efficient HDI 8 can be developed by achieving a uniform light distribution in the upper layer 10 of the light guide through the use of a novel method of light injection. New methods and apparatus are described for injecting light into the upper layer 10 of the light guide and for shaping the distribution of the injected light for the benefit of improved touch sensitivity. A method for manufacturing a laminated structure suitable for mass production is also described. The novel 3D light guide geometry described requires a new way to couple or “inject” light into the top plate 10, which minimizes light loss at geometric features (e.g., at curved portions of the top plate 10) and enables efficient use of available light, effectively distributing it to where it is most needed. Furthermore, the new light guide can be easily manufactured (e.g., using injection molding technology) and can use surface mount device (SMD) components to minimize the form factor and simplify construction.

[0115] By shooting the light into the top plate 10 closer to the beginning of the geometry where the light is most needed, the light does not travel a longer distance than necessary before reaching the active area of the touch screen that can detect a touch on the upper surface 23 of the top plate 10. In addition, the shot light does not disperse until it is "used", i.e. within the active touch detection area of the touch screen 8. An important aspect of efficiency is to ensure that all of the light traveling within the light guide is "useful" light, i.e. light traveling on the proper trajectory so that the touch detection process operates as intended. Light that is not useful in this way can contribute to noise but not to signal, so preventing stray light from propagating can be more important than simply maximizing the amount of light that enters the top plate 10 in order to achieve the best signal-to-noise ratio.

[0116] Referring to Figure 3 , an apparatus for shooting light from a light source 12 into a light guide 10 is shown. For example, Figure 3 The arrangement of Figure 1 may be incorporated as a top plate 10 of a touch detection system 8 such as

[0117] In this example, the light guide 10 is defined by a curved plate of constant thickness t L , where the thickness is defined as the distance between the upper surface 23 and the lower surface 25 of the light guide 10. The light guide 10 can be planar or various other three-dimensional (3D) shapes. Unlike conventional systems in which light is coupled into the light guide 10 through the edges of the light guide 10, in the example of Figure 3 the light is coupled into the light guide 10 at a location inserted from the edge of the light guide 10 (although the coupling location is not limited to this location in the light guide 10). In this way, the light is coupled into the light guide 10 at a location closer to the beginning of the geometry where the light is needed, i.e. closer to the active area of the light guide 10 where the light is used for touch detection.

[0118] As shown in Figure 3 , the light guide 10 includes a cavity or recess 30 for receiving and enclosing the light source 12, which in this example is an LED. The cavity 30 is defined in the second or lower surface 25 of the light guide 10 at the underside of the light guide 10 and extends partially through the thickness t L of the light guide 10 so as not to penetrate the upper surface 23 of the light guide 10. In this way, the cavity 30 extends from the lower surface 25 of the light guide 10 toward the upper surface 23 of the light guide 10 and terminates below the upper surface 23 so that a top surface 32 of the cavity 30 is located between the upper surface 23 and the lower surface 25 of the light guide 10. The portion of the light guide between the top surface 32 and the upper surface 23 defines a roof 34 of the cavity 30. In other words, the portion of the light guide 10 above the cavity 30 defines the roof 34 of the cavity 30 (see Figure 4 in particular).

[0119] The cavity 30 includesFigure 3 The front surface 36 and rear surface 38 and the side surface shown are shown. Figure 3 (Not shown in the diagram). As it moves in the direction from the lower surface 25 to the upper surface 23, the front surface 36 and the rear surface 38 tilt toward each other. In this way, the width of the cavity 30 gradually decreases, such that the width of the cavity 30 between its front surface 36 and rear surface or wall 38 decreases as it moves away from the lower surface 25 toward the upper surface 23 of the light guide 10. It should be noted that the rear surface 38 only needs to be tilted to produce the draft angle for injection molding. Now, particularly considering the light-coupled end of the cavity 30, the front wall 36 forms an angle with the plane of the light guide or top plate 10 in the region where the light source cavity 30 is coupled, such that the front wall 36 and the second or lower surface 25 of the top plate 10 form an obtuse angle within the top plate 10 to form a refractive input surface. In this example, the side surface tilts inward from the lower surface 25 to the upper surface 23, but this can vary in other examples. For example, the side surface may extend vertically between the upper surface 23 and the lower surface 25, but is typically provided with a ramp to enable injection molding. It should be understood that the shape of cavity 30 may vary in other examples.

[0120] When the light source is 12, Figure 3 When arranged in cavity 30, the light-emitting area 40 of light source 12 (from which light emitted from light source 12 is emitted) faces the front surface 36 of cavity 30. In this manner, light emitted from light source 12 enters light guide 10 through the front surface 36 of cavity 30 (which serves as the light coupling surface or wall of cavity 30). In this embodiment, absorbers 42 in the form of light-absorbing layers are provided on the top surface 32 and rear surface 38 of light source cavity 30 to block light emitted from light source 12 from leaving light source cavity 30 through its upper or rear surfaces 32, 38. In this way, absorbers 42 prevent unwanted stray light that cannot reach the effective touch detection area of ​​light guide 10 from emitting from above, behind, or to the side of light source 12. This advantageously removes stray light that may interfere with the touch detection system. In this example, absorbers 42 are also provided below the lower surface 25 of light guide 10, adjacent to light source cavity 30, to prevent light reflection from light source 12 in this area. In this way, light that does not meet the critical angle standard for total internal reflection can be blocked and cannot be transmitted in the light guide 10.

[0121] exist Figure 3 In one example, the light guide 10 includes a cavity 30 configured to surround a single light source 12. However, it should be understood that in other examples, the light guide 10 may include multiple cavities 30, each of which may be configured to surround one or more light sources 12. Furthermore, in some examples, the light guide 10 may include a single cavity 30 configured to surround multiple light sources 12.

[0122] Accordingly, as described above, at least one cavity 30 is cut into the underside of the light guide 10, the cavity 30 being large enough to accommodate a single light emitter 12 or a plurality of light emitters 12. The size and dimensions of the light source 12 dictate the size and dimensions of the cavity 30 required to accommodate the light source 12, with a gap tolerance to good mechanical design specifications. For mass produced optical components, injection molding is the manufacturing method of choice. This requires a minimum top thickness t R over the LED, which is functionally and aesthetically unacceptable. The top thickness t R is defined as the thickness of the top 34 of the cavity 30, which is defined as the distance between the top surface 32 of the cavity 30 and the upper surface 23 of the light guide. In Figure 3 the embodiment shown, the LED height h L is compared to a relatively thick light guide portion, such that the top 34 of the cavity 30 has sufficient thickness t R to accommodate the LED 12 without a sink in the upper surface 23 of the light guide 10 over the LED 12.

[0123] Figure 4 Another embodiment of an apparatus for launching light from a light source 12 into a light guide 10 for a touch sensitive optical system is shown. In this example, the light guide 10 includes a relatively thick first section 46 and a relatively thin second section 48 (i.e., a section of reduced width). The first section 46 is thicker than the second section 48. In other words, the distance between the first surface 23 and the second surface 25 of the light guide 10 is greater in the first section 46 than in the second section 48. The light source cavity 30 is disposed in the first relatively thick section 46 of the light guide 10. A ramped section 50 of the light guide 10, which decreases in distance between the first surface 23 and the second surface 25 in a direction extending away from the front wall 36 of the recess 30, joins the first section 46 (i.e., the thicker cavity section) with the second section 48 (i.e., the thinner light guide section).

[0124] Similar to the light source cavity 30 of Figure 3 the apparatus of Figure 4 the light source cavity 30 of the apparatus is defined in the lower surface 25 of the light guide 10 and extends partially through the thickness of the light guide 10, the cavity 30 terminating at a top surface 32 of the cavity 30 between the upper surface 23 and the lower surface 25 of the light guide 10, and the portion of the light guide 10 between the top surface 32 and the upper surface 23 defines a top 34 of the cavity 30. The cavity 30 includes a front surface 36 and a back surface 38 as shown in Figure 4 Figure 4 ​The front surface 36 and the rear surface 38 are inclined toward each other as they move in a direction from the lower surface 25 to the upper surface 23. Thus Figure 4 The cavity 30 is slightly tapered in width, such that the width of the cavity 30 between its front surface 36 and its rear surface 38 decreases as it moves away from the lower surface 25 of the light guide 10 toward the upper surface 23 of the light guide 10, but this tapering is not as pronounced in the device of Figure 4 The tapering of the cavity 30 in the device of Figure 3 is less pronounced than in the device of In this example, the side surfaces are inclined inwardly from the lower surface 25 to the upper surface 23, but this can vary in other examples. It will also be generally understood that the shape of the cavity 30 can vary in other examples.

[0125] Again, similar to the arrangement of Figure 3 The light emitting region 40 of the light source 12 disposed in the cavity 30 of Figure 4 faces the front surface 36 of the cavity 30, such that the front surface 36 of the cavity 30 acts as a light coupling surface. The light coupling surface 36 defines a refractive input face of the light guide 10 at which light from the light source 12 is refracted into the light guide 10. An absorber 42 is disposed on the top surface 32 and below the lower surface 25 of the light guide 10 adjacent to the light source cavity 30 for reasons similar to those already described in relation to Figure 3

[0126] Turning now to Figure 5 , a light source cavity 30 similar to that shown in Figure 4 has been incorporated into a light guide 10 having a curved geometry, but which is sized to enclose multiple light sources 12 (only one of which is labeled in Figure 5 for clarity) rather than a single light source 12. Figure 5 The light guide 10 of Figure 5 is curved in two dimensions, particularly in the y and z dimensions, as defined in Figure 5 The light guide 10 of Figure 5 is symmetrically extruded about the x-axis, also as defined in

[0127] Light emitted from the light sources 12 passes through the refractive input face 36 and through the ramped section 50 of the light guide 10, where the light is trapped in the light guide 10 by total internal reflection. The array of light sources 12 is spaced along the length of the linearly extending recess 30 to form a linear array within the recess 30 and thereby a substantially uniform light distribution in the body of the light guide or top plate 10.

[0128] The light coupling surface 36 through which light enters the light guide 10 as well as the ramped light guide section 50 are configured to take into account the spatial and angular characteristics of the light sources 12, and in particular to: a) maximizing the optical launch efficiency from the one or more light sources 12 into the light guide 10. This can be achieved, for example, by providing an optical polish on the light coupling surface 36; b) eliminating or minimizing optical losses, particularly in the vertical plane, by ensuring that light rays do not fall outside the critical angle range at the upper and / or lower surfaces 23, 25 of the light guide 10 (i.e. the angle of incidence of light rays striking the upper / lower surfaces 23, 25 relative to the surface normal defined thereto is not below the relevant critical angle defined relative to that surface normal); c) maximizing the touch sensitivity of the system incorporating the light guide 10 as described above by controlling the average light ray angle of incidence (relative to the surface normal) at the upper surface 23 of the light guide. In particular, the launch optic is configured such that the average angle of incidence of light rays emitted from the light source 12 and reaching the upper and lower surfaces 23, 25 of the light guide 10 is closer to the critical angle. The angle of incidence a of light rays striking the upper / lower surfaces 23, 25 is defined relative to the surface normal of the upper / lower surfaces 23, 25 as is common in the art and is shown fully and clearly in Figure 1 It has been shown that the depth of the evanescent field, i.e. the penetration of the evanescent field, increases as the angle of incidence of a light ray at the boundary experiences total internal reflection approaches the critical angle. Thus, configuring the launch optic such that light rays experiencing total internal reflection in the light guide 10 propagate as close to the critical angle as possible increases the evanescent field depth, which in turn improves the touch sensitivity of such a system utilizing frustrated total internal reflection in the touch detection process. It will be appreciated that the angle between the incident light rays from the light source 12 and the upper / lower surfaces 23, 25 of the light guide 10 can change as the light traverses the light guide 10 via total internal reflection, particularly if the light guide 10 is curved. For example, if the angle a at which light strikes the upper / lower surfaces 23, 25 of the light guide 10 decreases to fall below the critical angle, and thus below the threshold angle for total internal reflection, then the light will be lost from the light guide 10. With this in mind, the range of normal angles of incidence of light coupled into the light guide 10 can be selected so as to balance the benefits of increased evanescent field depth with the light loss that occurs when the angle of incidence a of the light rays falls below the critical angle. With these points in mind, it will be appreciated that the mounting of the light source 12 relative to the wall of the refracting face or each refracting face 36 can be arranged to refract the light so as to increase the evanescent field strength, whilst simultaneously confining the light within the top plate 10 by total internal reflection.

[0129] d) propagating the light rays particularly in the horizontal plane to optimize the uniformity of the light power density at the upper surface 23 of the light guide 10, thereby improving the uniformity of the touch response across the touch sensitive area of the system.

[0130] e) the optical cavity shape is large enough to accommodate a single or multiple light emitting packages 12 depending on the application, but small enough to minimize the distance between the back of the optical cavity 30 (i.e., the back surface 38 of the light source cavity 30) and the start of the active area of the touch surface.

[0131] f) the ease of manufacture of the optical cavity shape is improved.

[0132] In Figure 5 and 6 , the cavities 30 define linearly extending recesses in the top plate 10 for receiving multiple light sources 12, and are referred to as "trench-injection optical devices" (TIO) 52. In other embodiments, the cavities 30 are sized and arranged to enclose a single light source 12, as shown in Figure 7 , and are referred to as "pocket-injection optical devices" (PIO) 74. Other variants are possible. In Figure 5 and Figure 6 , the linearly extending recesses extend in a straight line across the light guide 10, although it should be noted that this can be different in other embodiments. For example, in other embodiments, the linearly extending recesses can extend along a curved path. In some variants, the cavities 30 can extend across the top plate 10, for example, along a conic or aspheric path, along a path defined by a spline curve, or along any other path composed of single or multiple segments, which are not listed here in their entirety, but are apparent to those skilled in the art.

[0133] It will be appreciated that one or more trench-injection optical devices 52 can be combined with one or more pocket-injection optical devices 74 within the same top plate 10, and / or more generally within the same touch-sensitive device or system.

[0134] In general, for a flat light guide 10 having upper and lower planar surfaces 23, 25 extending parallel to each other, once light is coupled or "injected" into the light guide 10, the light is confined within the light guide 10 as long as the angle between the reflected light ray and the surface normal remains equal to or greater than the critical angle determined by the refractive index of the material of the light guide 10. Figure 8a and Figure 8b show the path of a light ray propagating in a light guide 10 formed of an acrylic material and reaching the lower surface 25 of the light guide 10 at the critical angle. In Figure 8a , the lower surface 25 defines an interface between the acrylic material of the light guide 10 and an air gap defining the intermediate layer 14 between the light guide 10 and the substrate 18, such that the critical angle at the interface is about 42°. In Figure 8b , a layer of fluorinated polymer, fluorinated ethylene propylene (FEP) material is provided between the top plate 10 and the substrate 18 to define the intermediate layer 14, such that the critical angle at the interface is about 64°.

[0135] However, for light guides 10 having more complex surface profiles including, for example, 3D recesses or domes, additional requirements must be met to minimize light loss during propagation of light through the light guide 10. When using light sources 12 having a relatively small angle of divergence, a general rule for minimizing light loss from the light guide 10 is that any light guide curvature should follow a ratio of bend radius to light guide thickness that is greater than 5 to 1. That is, referring to Figure 40 , the ratio of the radius of curvature Rc of the light guide 10 in a given region to the thickness t p of the light guide 10 in that given region should exceed 5 / 1. This ratio can be referred to as the turntable angular curvature ratio Kd, such that Kd = Rc / tp> 5 / 1.

[0136] This rule is generally effective when using light sources 12 that emit light having a relatively small angle of divergence, but for light sources 12 having a larger angle of divergence of the light from the light source 12, the likelihood of at least some of the light rays from the light source 12 falling below the relevant critical angle and experiencing light loss from the light guide 10 increases, particularly if the light guide 10 is rapidly and continuously curved in opposite directions, e.g., the geometric profile of the light guide 10 experiences an “S” deviation.

[0137] In devices that utilize optical touch detection, lost light from the system, particularly lost light from the light guide 10, is highly undesirable. Escaped light, i.e., light lost from the light guide 10, can be reflected back into the system by a user and cause the system to falsely detect a touch. For example, even if a user’s hand does not touch the upper surface 23 of the light guide 10, a user’s hand near the light guide 10 can reflect escaped light back into the system, causing a false touch detection. In addition, escaped light reflected back into the system can reduce the accuracy of the finger press location determined by the system, and can reduce the overall press response. As will be explained below, this can be addressed by limiting the range of angles of light rays coupled into the light guide 10 from the light source 12, such that substantially all of the light rays propagating in the light guide 10 remain above the critical angle throughout their propagation in the light guide 10 and do not escape from the light guide 10 by falling below the critical angle.

[0138] Turning again to Figure 5 and Figure 6 the simplified optical geometry of the use of the trench-injection optic 52 will now be considered in more detail.

[0139] The trench-injection optic geometry is essentially a 2D design in the vertical plane, i.e., the y-z plane, which projects along the x-axis.

[0140] Rather than determining the ideal shape of the 3D geometry of the trench-injection optic 52 or pocket-injection optic (discussed in greater detail later) at one time, the problem is simplified by separating into vertical and horizontal profiles. The next section discusses how the horizontal and vertical profiles can be designed and optimized independently of one another, and then combined to achieve the complete 3D geometry of the trench-injection optic 52.

[0141] It can be appreciated that the optical performance in the vertical plane is not completely independent of the geometry in the horizontal plane (or vice versa), and that a full 3D optimization can further improve the optical performance of the trench-injection optic 52. However, considering the vertical and horizontal profiles separately enables a simplified optimization process that results in good coupling performance of the trench-injection optic 52.

[0142] Turning first to the vertical profile of the trench-injection optic 52 in the y-z plane, the key requirements for optimizing the trench-injection optic 52 design geometry in the vertical plane are: i. maximizing the light coupling efficiency into the light guide 10; ii. maximizing the light power density (or evanescent field) at the top surface 23 of the light guide 10; iii. minimizing the light loss in the light guide 10 (primarily caused by losses from the light guide top surface 23 and the light guide bottom surface 25). It should be noted that light lost from the system via the top 34 of the light guide 10 and the back wall 38 of the cavity 30, or light that reaches the printed circuit board (PCB) 54 below the light source 12, is not included in the following analysis; and iv. minimizing the distance between the back wall 38 of the trench-injection optic 52 and the active area of the light guide 10 (i.e., the area of the light guide 10 from which the system can detect a touch to the top surface 23 of the light guide 10).

[0143] A number of factors (primarily related to the numerical aperture of the optical system and the refractive index of the light guide material) can be used to control or limit the range of light ray angles propagating within the light guide 10, thereby minimizing light loss.

[0144] The size of the light source 12 that emits light into the light guide 10 is a key factor, and there are a number of suitable light sources on the market that are ideal for this application. LEDs 12 are suitable due to factors such as their small light source size, fast response, and wavelength range. However, it should be understood that the principles described herein apply to any suitable light source 12, and the present invention is not limited to the use of LEDs 12.

[0145] To ensure reasonable light coupling efficiency of the light entering the light guide 10, the size of the light source 12 is typically chosen to be less than one quarter of the thickness of the light guide. Also, depending on the application, a light source 12 with a wide or narrow angular light distribution can be chosen, with the light distribution being focused or spread accordingly. As previously mentioned, the goal here is to maximize the useful light coupling into the light guide 10, not simply to maximize all light coupling (including light at angles that do not produce a signal but can produce noise). The present application is primarily directed to the case of using a narrow angle light source 12, but the techniques described are equally applicable to wide angle light sources 12.

[0146] Increasing the distance between the light emitting area 40 (i.e., the LED tip 40) of the LED 12 and the refractive input face 36 (for a fixed aperture width, see related description below) narrows the range of vertical angles of light rays that are coupled (or "injected") into the light guide 10 by the refractive input face 36. Referring to Figure 9 , the distance between the LED tip 40 and the refractive input face 36 is represented by z LED , and the range of angles of light rays that are coupled into the light guide 10 in the vertical or z dimension is represented by . It will be appreciated that reducing the vertical angular ray range decreases light coupling efficiency, as light outside the vertical angular range is not coupled into the light guide 10. However, the benefit of reducing the vertical angular range is that it decreases the likelihood of light being lost from the light guide 10 during its traversal of the light guide 10, particularly in light guides 10 with a curvature that defines a tight radius of curvature in the vertical dimension.

[0147] Another way in which the range of angles of light rays that are coupled into the light guide 10 can be limited is to use an aperture 56. The aperture 56 can be defined using an absorptive mask 58 that is applied to the top surface 32 and along the base 60 of the cavity 30. The material of the absorptive mask 58 is chosen so as to absorb light in a range of wavelengths emitted by the relevant light source(s) 12 disposed in the cavity 30. In embodiments of the present application, the light source 12 disposed in the cavity 30 can emit light in the near infrared range of wavelengths, and the absorptive mask 58 can accordingly absorb light in the near infrared range of wavelengths. In some examples, the absorptive mask 58 can be black paint. As discussed further below, one approach that can be taken is to mask only the light in the "working" range for detection, while not masking other light, allowing such other light to be used for other purposes, e.g., the masking can act only on infrared light, while transmitting visible light.

[0148] It should be noted that while in Figure 9 the absorptive mask 58 is applied to the top surface 32 of the cavity 30 and along the base 60 of the cavity 30 to define the aperture 56, in other examples the aperture 56 can be defined by applying the absorptive mask 58 to other appropriate surfaces. For example, asFigure 10 As shown, the absorbing mask 58 can be applied to the upper surface 23 of the light guide 10 instead of to the top surface 32 of the cavity 30 to define the upper edge of the aperture 56. The absorbing mask 58 applied to the upper surface 23 of the light guide 10 extends far enough along the upper surface 23 to intercept light rays that have passed through the cavity top 34, but not so far as to intercept light rays that will undergo total internal reflection from the top surface 23. As shown, the absorbing mask 58 is applied to the upper surface 23 of the light guide 10 in the form of a strip of black tape. The absorbing mask 58 can be applied to the upper surface 23 of the light guide 10 in other ways, such as by painting, printing, or coating the upper surface 23 with an absorbing material. Figure 10 As shown, the absorbing mask 58 extends along the upper surface 23 over the entire length Lcof the cavity 30 and terminates at a location within the ramp section 50 of the light guide 10 that is offset from the cavity 30. Thereby, a section of the first surface 23 that is located above the light source cavity 30 and extends beyond the cavity 30 is masked to limit the range of angles at which light from the plurality of light sources 12 is incident at the first surface 23 of the light guide 10 to be reflected. It will be explained later how to use in-mold labeling (IML) or over-molding to obtain a light guide 10 with an absorbing mask 58, such as the absorbing mask described.

[0149] The angle and two-dimensional (2D) shape of the one or more optical surfaces of the light guide input cavity wall 36 for refracting (i.e., bending) light rays can also be configured to control or limit the range of angles of light rays propagating within the light guide 10. For example, Figure 11 An example is shown of a light source cavity 30 with a light coupling wall 36 shaped to define a symmetric lens, such that the light coupling wall 36 has a convex curvature. In other words, in this example, the front wall 36 of the light source cavity 30 is lenticular. The symmetric lens is tilted or angled with respect to the vertical axis y, such that the light coupling wall 36 is tilted inwardly toward the light source 12 from the lower surface 25 to the upper surface 23. The symmetric lens shape adds to the input wall 36 at a sufficient angle on the input face 36 to enable this geometry to be manufactured by injection molding. Figure 11 The lens of the light source cavity 30 helps to reduce the range of angles, and in particular the vertical range of angles, of light rays entering the light guide 10 .

[0150] If the light guide is incorporated as a top plate 10 in a system such as Figure 1 that uses a middle or intermediate layer 14 of material, such as a fluorinated polymer (FEP), instead of air, it is preferable to further limit the range of angles, and in particular the vertical range of angles, of light rays entering the light guide 10 from the light source 12 . The refractive index of FEP (i.e., 1.344) is higher than the refractive index of air (i.e., 1.0), meaning that the range of angles of light rays that exceed the critical angle at the boundary between the light guide or top plate 10 and the intermediate layer 14 and thus will undergo total internal reflection is reduced from about 48° (when the light guide 10 is formed of acrylic and the intermediate layer 14 is air) to 26° (when the light guide 10 is formed of acrylic and the intermediate layer 14 is FEP material). This results in Figure 8a andFigure 8b As shown in the diagram, they indicate that they fall within the middle layer of air 14 ( Figure 8a ) and FEP middle layer 14 ( Figure 8b The system's critical angle range is the range of light rays within its angular range. Therefore, it should be understood that, compared to systems utilizing air as the middle layer 14, systems utilizing the FEP middle layer 14 (e.g., Figure 1 In systems that utilize light from one or more light sources into the light guide 10, the vertical angle range of the light rays is more restricted so that virtually all incident light falls within the angle range that allows total internal reflection at the boundary between the light guide 10 and the intermediate layer 14. Therefore, a more restricted angle range is required in systems that use, for example, an FEP instead of air as the intermediate layer 14.

[0151] It is also important to manage the light directed downwards from the light source towards the PCB 54 on which the light source 12 is mounted, because if the light is not absorbed, a small portion may reflect off the PCB surface and generate unwanted stray light in the system.

[0152] With these factors understood, Figure 12 shows how to increase the utilization of, for example Figure 6 The average ray angle in the light guide 10 of the grooved incident optics 52 shown is designed to maximize the evanescent field and, consequently, the touch sensitivity, but not to make the end of the angle range too close to the critical angle, which would result in high optical loss of the light guide 10.

[0153] refer to Figure 12a Curve 62 represents the light loss from the system (y-axis) for different tilt angles of the optical coupling surface (x-axis). (See reference...) Figure 12b and Figure 12c The tilt angle is defined as the tilt angle of the optical coupling surface relative to the vertical axis y. When the optical coupling surface extends vertically, as... Figure 12b As shown, the tilt angle is defined as 0°. When the optical coupling surface is tilted to extend at an angle relative to the vertical direction, the tilt angle is non-zero, as shown below. Figure 12c As shown, the optical coupling surface of the photoguide has a 50° tilt angle. It should be noted that... Figure 12c In the middle, the light source 12 is installed such that the light emitted from the light source 12 is mainly tilted towards the front wall 36 of the recess 30.

[0154] like Figure 12a As shown, the light lost from the upper and lower surfaces of the light guide at a tilt angle of 50° ( Figure 12c The lower angle is at 0° of inclination ( Figure 12b) greater. This is because increasing the tilt angle of the light coupling surface from 0° to 50° reduces the angle of incidence of light from the light source reaching the light coupling surface, where the angle of incidence is defined as the angle between a light ray and the surface normal of the light coupling surface. In a device utilizing a 50° tilt angle, the angle of the light rays relative to the surface normals at the upper and lower surfaces of the light guide is reduced because the deflection of the light rays due to refraction upon passing through the light coupling surface is increased, compared to a device utilizing a 0° tilt angle. In this way, the likelihood of at least some of the light falling below the critical angle and being lost from the system increases.

[0155] Curve 64 represents the light coupled into the light guide 10 (y-axis) in microwatts (pW) for different tilt angles (x-axis), and shows that the power of light coupled into the plate 10 increases as the tilt angle increases.

[0156] Curve 66 represents the power density at the upper surface 23 of the light guide 10 for different tilt angles. Curve 66 shows that increasing the tilt angle increases the power density of the upper surface. A higher power density at the upper surface of the light guide represents a stronger evanescent field, which in turn allows for better touch sensitivity in such a system utilizing frustrated total internal reflection in a touch detection mechanism.

[0157] Understanding how the parameters described above in relation to Figures 12a to 12c allowing the appropriate tilt angle of the light coupling surface 36 to be selected in order to balance the advantages of stronger evanescent fields and better touch sensitivity at higher tilt angles with the disadvantage of increased loss from the system at higher tilt angles.

[0158] With reference to Figures 13a to 13c , in another embodiment, touch sensitivity can be further increased not only by angling the trench wall angle (i.e. the tilt angle of the light coupling surface 36), but also by rotating the LED orientation in the yz plane, although this does make manufacturing more complex. With reference to Figure 13c , the light source 12 emits light symmetrically about its central axis C and is mounted at an angle to the plane of the top plate 10 such that its central axis C is tilted towards the first surface 23 of the top plate 10. Thus, light emitted from the light source is primarily tilted towards the first surface 23. Furthermore, the light source 12 is mounted such that its central axis C is perpendicular to the front wall 36 of the light source cavity 30. It should be noted that in other examples, the light source 12 can be mounted such that its central axis C is slightly offset from an axis that is perpendicular to the front wall 36 of the light source cavity 30.

[0159] With reference to Figure 14 , in another embodiment, an extruded section 68 is added to the lower leading edge of the wedge 50 or trench to help “trap” any unwanted stray light from the bottom edge 70, to avoid a sharp edge and to provide support for the light guide 10. The extruded section 68 defines a linear protrusion on the second surface 25 of the light guide 10 that extends away from the first surface 23. As shown inFigure 14 As shown, the linear extent of the linear protrusion 68 is substantially parallel to the linear extent of the light source cavity 30. In this example, the linear protrusion 68 has a rectangular cross-section perpendicular to its linear extent. In other embodiments, the shape of the protrusion 68 can vary. For example, the linear protrusion 68 can have a sectorial or similar cross-section perpendicular to its linear extent. It will be appreciated that, Figure 14 The slope of the light guide 10 is linear, i.e. the distance between the first surface 23 and the second surface 25 of the light guide 10 decreases linearly in the slope section 50 of this example. Referring to Figure 15 In another embodiment, the slope of the light guide 10 is not linear but is reduced using a faceted or other continuous non-linear function (e.g. curved, asymmetric, spline) or a combination of suitable functions. In other words, in this embodiment, Figure 15 In this embodiment, the distance between the first surface 23 and the second surface 25 of the light guide 10 decreases non-linearly in the slope section 50.

[0160] The key requirements or techniques for optimizing the trench-injection optical design geometry in the horizontal plane are as follows: i. Achieve a defined light power density (or evanescent field) target across the top surface 23 of the light guide 10; ii. Achieve a defined uniformity target for the light power density across the entire active area of the touch surface 23 of the light guide 10 (typically with units of μW / mm 2 As previously mentioned, the active area of the light guide 10 is the area of the touch surface 23 where the system can detect a touch. For example, for a touch screen, the active area can be a wide, generally rectangular area. For a finger swipe groove, i.e. a portion of the light guide top surface 23 that includes one or more grooves that act as a finger guide, the active area can be an elongated, narrow area 72, as shown in Figure 16 Having a uniform light power density within the active area of the light guide 10 is beneficial as it improves the uniformity of the touch response across the active area; iii. Achieve the uniformity target for the light power density across the active area of the touch surface 23 using a minimum amount of light sources 12; iv. Achieve the uniformity target for the light power density across the active area of the touch surface 23 at the shortest possible distance from the one or more light sources 12; v. Minimize the distance between the back surface 38 of the trench-injection optical device 52 (i.e. the back surface 38 of the light source cavity 30) and the active area of the light guide 10.

[0161] The optical geometry of the trench-injection optical device 52 is beneficial in improving the light distribution across the top light guide surface 23.

[0162] In embodiments that utilize a light guide 10 having a slope, the slope of the light guide 10 is linear, i.e. the distance between the first surface 23 and the second surface 25 of the light guide 10 decreases linearly in the slope section 50 of this example. Referring toFigure 5 or Figure 6 The horizontal light distribution on the top surface 23 of the 2D curved geometry of the light guide 10 of the trench-injection optic 52 is primarily derived from the LED light distribution and the light source array layout, i.e., the arrangement of the light sources 12 disposed within the cavity 30 of the trench-injection optic 52.

[0163] The light source array layout refers to the spacing and orientation of the light sources 12 in the light source cavity 30. The trajectory of the LED output can also be changed by adjusting the geometry of the light source cavity 30, particularly the shape of the light coupling face 36. Referring to Figure 17a , an embodiment of a trench-injection optic 52 is shown having a flat planar light coupling face 36. Referring to Figure 17b , an embodiment of a trench-injection optic 52 is shown having a curved light coupling face 36. In particular, Figure 17a The light coupling face 36 of the embodiment of

[0164] In general, the further the LED array is from the touch geometry, the improved uniformity of light within the light guide 10 from the light sources 12 will be. In other words, the uniformity of light within the light guide 10 improves with increasing distance from the light sources 12 of the trench-injection optic 52, such that the uniformity of light in the active area improves with increasing distance of the active area from the light sources 12.

[0165] However, in many applications, it is advantageous for the active area to be closer, in some cases as close as possible, to the light sources 12 of the light guide 10 for aesthetic reasons of the final touch screen product or in view of space considerations / constraints. The ideal situation is to minimize the separation of the array from the geometry and maximize the spacing between adjacent light sources 12 that meet uniformity targets.

[0166] In embodiments, masking is used, i.e., using an absorbing mask layer 58 or element to absorb light, to absorb light rays that reach the upper surface 23 or lower surface 25 of the light guide 10. In other words, regions of the first or upper surface 23 and / or the second or lower surface 25 can be masked to prevent light from the plurality of light sources 12 in the trench or recess 36 from total internal reflecting within the light guide 10.

[0167] The mask layer 58 or element can be arranged so as to control, for example, the location at the upper surface 23 where light rays are allowed to reflect from the upper surface 23, which in turn allows light rays to be emitted from the light sources 12 at an angle such that these light rays do not experience total internal reflection from the top surface 23 but are instead absorbed, thereby controlling light leakage from the upper surface 23 of the light guide 10. Since the light source intensity distribution can vary with angle in the xz-plane, the mask edge can also vary with angle in the xz-plane accordingly.

[0168] In embodiments where no lensing is used to couple light emitted from the light sources 12 into the light guide 10, the approach described above for the trench-injection optics 52 can allow flexibility in light source component placement. This is because in this case the precise position and orientation of each light source 12 within the cavity 30 is less critical than if the light from the light sources 12 were to propagate through a lens before entering the light guide 10.

[0169] Thus, when lensing is not used, the impact of variations in light source component placement (e.g. due to assembly tolerances) on the optical performance (e.g. irradiance distribution or optical efficiency) of the array of trench-injection optics 52 can be reduced.

[0170] The approach for injecting light into the light guide 10 using pocket-injection optics (PIO) 74 will now be described.

[0171] For example, in Figure 7 , FIG. 18, Figure 19 and Figure 20 examples of pocket-injection optics 74 are shown.

[0172] The pocket-injection optics 74 use a full 3D geometry construction to control the horizontal and vertical angular distribution of light from the light sources 12. To this end, the 3D shape of the light source cavity 30 in which the light sources 12 are disposed is designed to control the angular distribution of light coupled into and travelling within the light guide 10. This optical design of the pocket-injection optics 74 controls the light distribution in the vertical direction (y-dimension) in a similar way to the trench-injection optics 52, and provides additional control over the intensity distribution in the horizontal direction (x-dimension), which can be used to address differences in the vertical intensity distribution with angle, and to influence the convergence or divergence of the light distribution on the surface 23 of the active area of the light guide 10.

[0173] Considering first the vertical profile of the pocket-injection optics 74 in the y-z plane, the key requirements for optimising the pocket-injection optics design geometry in the vertical plane are the same as for the trench-injection optics 52, and for the sake of clarity and completeness these will be repeated below: i. maximising the light coupling efficiency into the light guide 10; ii. maximising the light power density (or evanescent field) at the top surface 23 of the light guide 10; iii. minimising light loss in the light guide 10 (primarily caused by losses from the light guide top surface 23 and the light guide bottom surface 25). It should be noted that light lost from the system via the top of the light guide 10 34 and the back wall 38 of the cavity 30, or light reaching the printed circuit board (PCB) 54 below the light sources 12, is not included in the analysis below; and iv. Minimize the distance between the back wall 38 of the trench-injection optic 52 and the active area of the light guide 10 (i.e., the area of the light guide 10 where the system can detect a touch to the upper surface 23 of the light guide 10).

[0174] All of the factors discussed above for the trench-injection optic 52 (primarily related to the numerical aperture of the optical system and the index of refraction of the light guide material) also apply to the pocket-injection optic 74, and will not be repeated here for the sake of brevity. Here, only the primary additional factors that can be used to control or limit the range of vertical light ray angles propagating within the light guide 10 are highlighted, in order to optimize the key requirements discussed above.

[0175] The angle, shape, and taper of the refractive input face 36 (also referred to as the light coupling face 36 of the light source cavity 30) can be used to control the range of vertical angles of light rays propagating within the light guide 10. As discussed with respect to the trench-injection optic 52, the depth of the evanescent field, i.e., the penetration of the evanescent field, increases as the angle of incidence of a light ray experiencing total internal reflection at the boundary between two regions of different index of refraction approaches the critical angle. Thus, configuring the injection optic 52, 73 such that light rays propagate in the light guide 10 at angles as close to the critical angle as possible increases the evanescent field depth, which in turn improves the touch sensitivity of such a system utilizing frustrated total internal reflection in the touch detection process.

[0176] As discussed with respect to Figure 12b and Figure 12c Increasing the angle of the light coupling face 36 relative to the vertical (y) axis (i.e., the slope or tilt of the refractive input face 36) can be used to increase the evanescent field at the upper surface 23 of the light guide 10 by ensuring that light from the light source 12 within the light guide 10 propagates as close to the critical angle as possible, in a similar manner as discussed with respect to the trench-injection optic 52. In a similar manner, including a ramped section 50 in the light guide 10 (between the thicker section 46 and the thinner section 48 including the light source cavity 30) can be used to increase the evanescent field at the upper surface 23 of the light guide 10, as can adjusting the taper of the ramped section 50, or some combination thereof. However, in the pocket-injection optic 74, these parameters can be varied in the sides of the light coupling face 36 extending back toward the rear of the light source cavity 30, for example to compensate for variations in the light source intensity distribution.

[0177] Figure 18a Embodiments of a pocket-injection optic 74 are shown, for example, in a top plate 10 of a touch detection system such as Figure 1 .

[0178] Similar to the trench-injection optic 52 arrangement of Figure 5 and Figure 6 , Figure 18aThe pocket-type optics 74 includes a cavity or recess 30 in the lower side of the light guide defined by the top plate 10. The cavity 30 has an optical coupling surface 36, which serves as a refractive input surface for coupling light from the light source 12 disposed in the cavity 30 into the body of the top plate 10.

[0179] exist Figure 18a In this embodiment, the refractive input surface 36 defines a curved path between a first end 76 and a second end 78, and defines a curved length between the first end 76 and the second end 78. The refractive input surface 36 extends from the first end 76 to the second end 78 around the light source 12 so as to partially surround the light source 12. The front side of the light source 12 defines a light-emitting region 40 of the light source, which faces the refractive input surface 36 of the cavity 30. In use, light is emitted from the light-emitting region 40 of the light source 12 and passes through the refractive input surface 36 into the body of the top plate 10, where the light undergoes total internal reflection.

[0180] Still refer to Figure 18a The height of the refractive input surface 36, i.e., the distance between the upper edge 80 and the lower edge 82 of the refractive input surface 36, varies along the curved path between the first end 76 and the second end 78 of the refractive input surface 36. Specifically, in Figure 18a In one embodiment, the height of the refractive input surface 36 increases from a minimum height at the first end 76 and the second end 78 to a maximum height at the center position between the first end 76 and the second end 78 along the length of the refractive input surface 36.

[0181] exist Figure 18a In this arrangement, the tilt angle or slope of the refractive input surface 36 also varies along the curved path between the first end 76 and the second end 78 of the refractive input surface 36. Specifically, the tilt angle of the refractive input surface 36 increases from the first end 76 along the curved length of the refractive input surface 36 to the center position. Similarly, the refractive input surface 36 increases from the second end 78 along the curved length of the refractive input surface 36 to the center position.

[0182] In other examples, the height and tilt angle of the refractive input surface 36, as well as the variation in the height and tilt angle of the refractive input surface 36 between the first end 76 and the second end 78, may differ from those of other examples. Figure 18a The arrangement of the refractive input surface 36. In some examples, the height and tilt angle of the refractive input surface 36 may be constant over the entire bending length of the refractive input surface 36. For example, the parameters defining the shape and arrangement of the refractive input surface 36 may vary depending on the parameters of the associated light source 12.

[0183] Figure 18b Showing the integration in the top plate 10 Figure 18a The pocket-type optics 74 has a sloping section 50 between the thicker section 46 of the combined light source cavity 30 and the thinner section 48 of the top plate 10.Figure 18b In the example, the lower surface 25 of the top plate 10 surrounding the light source cavity 30 slopes upward toward the upper surface 23 of the top plate 10 from the thicker section 46 to the thinner section 48, defining a ramp section 50 of the top plate 10. Figure 18b In this embodiment, the slope of the lower surface 25 near the center of the bending length of the refractive input surface 36 is greater than the slope at the first end 76 and the second end 78 of the refractive input surface 36. In this way, the taper of the top plate 10 is greater in front of the light source 12, particularly at the light-emitting area 40 of the light source 12, than at the side of the light source 12.

[0184] Now back Figure 7 The pocket-type optics 74 of this embodiment includes a light source cavity or recess 30 having a plurality of refractive input surfaces 36. The pocket-type geometry has the same basic control over the vertical light distribution as the groove-type optics 52, but with additional control over the horizontal intensity distribution. This can be used to address differences in the vertical intensity distribution with angle, as well as the convergence or divergence of light distribution on the surface of the effective area where a touch can be detected. It should be recognized that different touch geometries may require pocket-type optics 74 with narrow or wide light distributions.

[0185] Figure 41a A pocket-type optics 74 is shown that provides a narrow light distribution. Figure 41a The pocket-type optics 74 includes a single refractive input surface 36 with a convex curvature in the xz plane. Light emitted from the light source 12 (in [the xz plane]) passes through the refractive input surface 36. Figure 41a The middle part is represented by multiple light rays 79. For clarity, in Figure 41a The horizontal distribution of the light (only two rays are marked in the image) is shaped by the refractive input surface 36 to provide a narrow distribution of light in the light guide 10. This narrow light distribution is suitable, for example, in elongated, narrow effective regions, such as those used in applications like... Figure 16 The effective area of ​​slider 72 shown.

[0186] Figure 41b A pocket-type optics 74 is shown, which provides a wide light distribution. Figure 41b The pocket-type optics 74 has a similar Figure 7 The similar configuration shown has three refractive input surfaces 36, which are used to filter light from the light source 12 (by... Figure 41b The multiple rays 79 (represented by only two rays for clarity) are horizontally shaped to provide a broad light distribution in the light guide 10. This broad light distribution can be suitable, for example, for applications such as... Figure 28 The turntable device shown.

[0187] Figure 7Examples include a first side refractive input surface 84, a second side refractive input surface 86, and a central refractive input surface 88. The light source 12 is disposed in the recess 30 such that light is coupled into the body of the top plate 10 through the refractive input surface 36. The light source cavity 30 is disposed in a relatively thick first section 46 of the light guide 10. A ramp section or wedge 50 of the light guide 10 connects the first section 46 to a thinner (or narrower) second section 48 of the light guide 10, and is located between the recess 30 and the narrower section 48. In the narrower section 48, the distance between the first surface 23 and the second surface 25 is substantially constant, but smaller than the distance between the first surface 23 and the second surface 25 at the recess 30.

[0188] The first side refractive input surface 84 extends along a curved path between its first end 90 and second end 92. When the light source 12 is used in the cavity 30, the first end 90 of the first side refractive input surface 84 is positioned on the first side 94 of the light source 12. The central refractive input surface 88 extends along a curved path between its first end 96 and second end 98, and combines with the first side refractive input surface 84 and the second side refractive input surface 86. The second side refractive input surface 86 extends along a curved path between its first end 100 and second end 102. When the light source 12 is used in the cavity 30, the second end 102 of the second side refractive input surface 86 is positioned on the second side 104 of the light source 12. The central refractive input surface 88 is located directly in front of the front of the light source 12, such that the light-emitting area 40 of the light source 12 faces the central refractive input surface 88.

[0189] In this example, two side refractive surfaces 84 and 86 are symmetrically arranged around and adjacent to the central refractive input surface 88. (The sentence appears to be incomplete and requires further context.) Figure 7 The lieutenant general understands that in this example, the central refractive input surface 88 has a different curvature than the side refractive surfaces 84 and 86.

[0190] In this manner, light emitted from the light source 12 is coupled into the body of the top plate 10 via the central refractive input surface 88 in a direction generally in front of the light source 12, and light emitted from the light source 12 is coupled into the top plate 10 via the first side refractive input surface 84 and the second side refractive input surface 86 in a generally lateral direction. The arrangement of the side refractive input surfaces 84, 86 or the wings extending from the central refractive input surface 88 provides better control over the intensity distribution of light from the light source 12 in the light guide 10.

[0191] Refraction input surfaces 84, 86, 88, for example, with Figure 12c and Figure 15The illustrated manner is similar to the manner in which the lower surface 25 of the light guide 10 is inclined inwardly toward the light source 12 from the upper surface 23 of the light guide 10. In other words, the walls of the refractive input faces each form an angle with the plane of the top plate 10 such that the refractive input faces 84, 86, 88 form an obtuse angle with the second surface 25 of the top plate 10 within the top plate 10.

[0192] As discussed with respect to Figure 12c providing the inclined input faces 84, 86, 88 allows control of the range of vertical angles of the light rays propagating in the light guide 10 and, in particular, can be used to push the angles of the light rays toward the critical angle to improve evanescent field penetration at the upper surface 23 of the light guide 10 and improve touch sensitivity.

[0193] The curvature along the length of the refractive input faces 84, 86, 88 provides control over the horizontal spreading of the light rays in the x-z plane of the light guide 10. The different geometries, and in particular the different horizontal curvatures of the first side refractive input face 84, the second side refractive input face 86, and the center refractive input face 88 in the x-z plane, allow for enhanced control over the horizontal distribution of the light rays from the light source 12 in the light guide 10.

[0194] In the example of Figure 7 and Figure 20 the curvature of the center refractive input face 88 defines a generally elliptical shape in the horizontal or x-z plane of the light guide 10. In particular, the center refractive input face 88 defines a semi-elliptical shape in the horizontal plane, with the horizontal distance in the x-dimension between the first end 96 and the second end 98 of the center refractive input face 88 defining the minor axis of the ellipse. The center refractive input face 88 is configured to spread light emitted from the light source 12 and incident on the center refractive input face 88 in the horizontal (x-z) plane of the light guide.

[0195] The curvatures of the first refractive input face 84 and the second refractive input face 86 in the horizontal plane are selected so as to redirect light rays to reach these appropriate portions. In the embodiment of Figure 7 and Figure 20 the first refractive input face 84 and the second refractive input face 86 are configured to limit the horizontal spreading of the light reaching these portions in the light guide 10, as illustrated in Figure 20 .

[0196] It should be noted that in other embodiments, the curvatures of the refractive input faces 84, 86, 88 can vary. For example, one or more of the refractive input faces 84, 86, 88 can have a conic curvature, or define a spline curve, above. Figure 19 The top plate 10 is shown incorporating two pocketed-injection optics 74 having a geometry similar to Figure 7similar shape to the optics of FIG. 1, and shows that an absorbing mask layer 58 can be provided on the upper surface 23 of the light guide 10 to prevent stray light from the light source 12 from escaping the light guide 10, similar to Figure 3 , Figure 4 and Figure 10 mask 58. As previously mentioned, masking as shown in Figure 19 is used to control light leakage from the light guide 10, and in particular to block light rays that fall below the critical angle in the masked area and would therefore directly pass through and out of the upper surface 23 of the light guide 10. In the embodiment of Figure 19 , the front edge 106 of the mask 58 terminates before the first total internal reflection light ray reaches the light guide upper surface 23, and defines the beginning of the active area of the light guide 10 in which touches on the upper surface 23 of the light guide 10 can be detected. In other words, substantially all of the light from the light source 12 that reaches the masked area of the upper surface 23 of the light guide 10 falls below the critical angle and would escape the light guide 10 without the mask 58. Thus, the mask 58 does not absorb the "useful" light that would otherwise experience total internal reflection at the upper surface 23. As previously mentioned, one possibility is to mask only the light in the "working" range for detection, and not to mask other light, allowing it to be used for other purposes, e.g., the masking can operate only on infrared light, while visible light is transmitted.

[0197] In the example of Figure 19 , the mask 58 is shown as extending over both pocket-injection optics 74. It should be appreciated that in some examples the mask 58 can be provided over all of the pocket-injection optics 74 of the light guide 10, or only over some of the pocket-injection optics 74 of the light guide 10. Further, in some examples the mask can extend only partially over some or all of the pocket-injection optics 74 of the light guide 10. The key requirements or techniques for optimizing the pocket-injection optics design geometry in the horizontal (x-z) plane are the same as those discussed with respect to the trench-injection optics 52, as follows: i. Achieve a defined light power density (or evanescent field) target across the top surface 23 of the light guide 10; ii. Achieve a defined uniformity target for the light power density (pW / mm 2 ) across the entire active area of the touch surface 23 (which can be a wide rectangular area for a screen, but a long narrow area for a finger slider groove, see Figure 16 ); iii. Achieve the uniformity target using the minimum amount of sources 12; iv. Achieve the uniformity target in the shortest possible distance from the source(s) 12; v. Minimize the distance between the back surface 38 of the pocket shooter optic 74 and the active area.

[0198] However, the horizontal profile control in the 3D geometry of the pocket shooter optic 74 allows direct control of the horizontal intensity distribution from the light source 12 using key control parameters.

[0199] A single or multiple refractive input face optic profiles are used in the pocket shooter optic 74 to spread or collimate the light distribution to suit the required application. Figure 20 The geometry of a multiple refractive input face is shown in Figure 7 , Figure 19 and Figure 20 , which has three different sections (first side refractive input face 84, second side refractive input face 86 and central refractive input face 88) with different geometric profiles, and is incorporated in the top plate 10 of a touch screen that requires a wide light distribution.

[0200] Figure 21a The pocket shooter optic 74 is shown in Figure 20 , and the light rays from the light source 12 propagating in the light guide 10 are shown to provide a wide intensity distribution in the horizontal (x-z) plane at the active area of the light guide 10.

[0201] Figure 21b The narrow horizontal intensity distribution of the output from the light source 12 is shown in the arrangement of Figure 21a before passing through the refractive input faces 84, 86, 88 of the pocket shooter optic 74. Figure 21c The intensity distribution of the light from the light source 12 within the light guide 10 after passing through the refractive input faces 84, 86, 88 of the pocket shooter optic 74 is shown in the active area of the light guide 10 located in the thinner region 48 of the light guide 10. As will be appreciated from Figure 21c , the refractive input faces 84, 86, 88 widen the horizontal intensity distribution of the light from the light source 12 to provide a wide intensity distribution in the horizontal plane shown in Figure 21c . Thus, Figure 21c shows the resulting wide intensity distribution in the horizontal (x-z) plane of the light guide 10 produced by using the pocket shooter optic 74 of Figure 21a .

[0202] It will be appreciated that other geometries can be used for one or more of the refractive input faces of the pocket shooter optic 74 to provide different horizontal light distributions as required or desired to match the touch geometry for a particular touch screen application.

[0203] The shape of the refractive input wall (i.e., one or more refractive input faces) of the pocket shoot-in optic 74 advantageously provides direct control over the xz intensity distribution in the light guide 10 and enables an array of pocket shoot-in optics 74 to provide improved uniformity, particularly when close to the light source 12. The array of pocket shoot-in optics 74, each providing a predetermined level and vertical shaping of the light from its associated light source 12, can provide improved uniformity and control of the horizontal intensity distribution when compared to an equivalent array of trench shoot-in optics 52. Generally, the angular light distribution precision achieved with the approach employing pocket shoot-in optics 74 enables the same uniformity to be achieved with fewer light sources 12.

[0204] Another advantage of the pocket shoot-in approach is that the available light power from the light source 12 can be used more efficiently (and electrical power consumption is less) because the light is distributed where it is needed, i.e., the active area of the light guide 10, and is not wasted in areas of the light guide 10 where it is not needed.

[0205] Due to its compact size, the pocket shoot-in optic 74 also allows greater flexibility in positioning the light source 12, which provides more space for other optical or mechanical features or electrical components or assemblies.

[0206] Furthermore, if one light source 12 fails in an array of pocket shoot-in optics 74, the combined light distribution is less affected than with an array of trench shoot-in optics 52 because all of the pocket shoot-in optics 74 can have the same light distribution. Likewise, any inherent LED differences in an array of pocket shoot-in optics 74 are less pronounced. For example, if the optical output of one light source 12 is significantly different from the optical output of an adjacent light source 12 in an array of pocket shoot-in optics 74, the impact on the light distribution can be less when compared to a similar scenario in a trench shoot-in optic 52 with an array of light sources 12.

[0207] In some cases, it can be desirable to provide a combination of trench shoot-in optics 52 and pocket shoot-in optics 74 in a single device. For example, a device can be provided with separate “active areas” masked from each other, effectively creating multiple devices or sub-devices, and different optic types can be used for each device, fitting the overall functionality of the relevant active area. For other device types, it can be desirable to use both trench shoot-in optics 52 and pocket shoot-in optics 74 to provide active light transport across the entire device, which is particularly applicable to cases where the shape of the active area is complex.

[0208] Those skilled in the art will appreciate that the placement of the light source 12 relative to the one or more refractive input faces 36, 84, 86, 88 will affect the shaping provided by the one or more refractive input faces 36, 84, 86, 88 of the pocket launch optic 74, and so this should be taken into account when positioning the light source 12 in the light source cavity 30. In the field of optical elements, the use of the trench launch optic 52 or pocket launch optic 74 structures discussed earlier, in conjunction with surface mount (SMD) type light sources such as LEDs, has certain key advantages. The smaller the light source package, the smaller the volume of the light source cavity 30 required in the lower side of the light guide 10, and the less intrusive the light source 12 and associated cavity 30 are to other functional elements in the assembly. However, it has been found that the light distribution from some LEDs 12 is not ideal, and can result in lower efficiency and uniformity.

[0209] The application of light sources 12, particularly LEDs, for touch screens can generally be divided into two groups related to their angular light intensity distribution. LEDs 12 with a wide angular range in the horizontal direction and a narrow angular range in the vertical direction are best suited for applications where the area to be illuminated is wide, such as screen, dome, or turntable geometries. In these cases, the intensity distribution should have a “soft” edge so that any overlap with an adjacent pocket launch optic 74 produces a uniform irradiance distribution.

[0210] LEDs 12 with a narrow angular range in the horizontal direction and a narrow angular range in the vertical direction are best suited for applications where the area to be illuminated is narrow, such as for slider and toggle geometries. In these cases, it is acceptable for the intensity distribution of the LED 12 to have a “hard edge” because the geometry is typically illuminated by at least one pocket launch optic 74 at each end of the geometry, and there is no need to overlap the light distribution of adjacent LEDs 12.

[0211] It should be noted that the intensity distribution forward direction is aligned along the z-axis (as defined using the coordinate system in Figure 5 and that the intensity distribution is symmetric about the y-z and x-z planes.

[0212] For example, SMD LEDs currently on the market that are suitable for use in the pocket launch optic 74 generally fall into two groups.

[0213] Referring to Figure 22a , wide-angle SMD LEDs have an intensity distribution that is wide “batwing” shaped in both the horizontal (x-z) plane and the vertical (x-y) plane.

[0214] Figure 22aThe wide, gently sloped "soft edge" of the horizontal profile provides a good starting point for achieving reasonable uniformity in the horizontal plane, and can be further improved when combined with pocket shooter optics 74 having an appropriate horizontal lens profile on the refractive input face 36, 84, 86, 88 (i.e., an appropriate geometry in the x-z plane for appropriate horizontal beam shaping).

[0215] However, in the vertical profile of the Figure 22a wide distribution cannot be well matched to the numerical aperture of the pocket shooter optics 74, even with an appropriate horizontal profile of the one or more refractive input faces 36, 84, 86, 88. This results in poor light coupling efficiency into the light guide 10 incorporating the pocket shooter optics 74 and LED light source 12.

[0216] Referring to Figure 22b and Figure 23b narrow angle SMD LEDs have intensity distributions that are narrow in both the horizontal (x-z) plane and the vertical (x-y) plane. Referring to Figure 23a This type of LED uses a round lens that focuses a portion of the light from the LED chip. Light that misses this focusing effect creates a "halo" of large angle rays around the central narrow angle cone of rays. By appropriately adjusting the distance of the LED 12 from the one or more refractive input faces 36, 84, 86, 88, the narrow cone of rays from the LED 12 can be matched to the numerical aperture of the pocket shooter optics 74 in the vertical plane. In the horizontal plane, the narrow cone of rays can be spread using a conic profile on the pocket shooter optics 74 that has been shown to give the desired light distribution in the light guide 10. However, the halo of light emitted by the sidewall 108 of the LED 12 results in poor light coupling efficiency and causes problems with stray light management in the assembly.

[0217] In view of the foregoing, Figure 24a An hyper-elliptical LED package (HE-LED) 109 design is shown. The package 109 can be used, for example, in combination with a pocket shooter optics geometry that has no optical power, such that the refractive input face 36 has no lensing effect for light received from the light source 12, referred to as a 0%- PIO. The package 109 can also be used in combination with other shooter optics geometries (e.g., a geometry with optical power) such that the front wall 36 through which light from the light source 12 enters the light guide 10 provides a lensing effect. For example, the front wall 36 can be configured to provide a lensing effect in the horizontal dimension, the vertical dimension, or both, to provide improvements in the horizontal and / or vertical light distribution in the light guide 10 as desired.

[0218] Figure 24aThe packaged light-emitting diode 109 includes a bare LED die or chip 110 and a lens 112. The lens 112 is in the form of a cylindrical lens, which significantly improves the optical coupling efficiency between the light source 12 and the light guide 10, as well as the uniformity of light in the light guide 10. The light emitted through the cylindrical lens 112 has a narrow-angle distribution along a first axis and a wide-angle distribution along a second axis orthogonal to the first axis. In this way, Figure 24a The packaged LED 109 is ideally suited for touchscreen applications.

[0219] like Figure 24a As shown, in this example, the cylindrical lens 112 is formed as a substantially oblate ellipsoidal lens 112a truncated within a body having two first truncated portions 114 and one second truncated portion 116. The two first truncated portions 114 are perpendicular to the axis A of the oblate ellipsoid and equidistant from its longest radius. The second truncated portion 116 is parallel to the axis A of the oblate ellipsoid and perpendicular to the two first truncated portions 114. In other examples, the shape of the lens 112 may be similar to... Figure 24a The difference is, for example, that it is a defined oblate spheroid.

[0220] Figure 24a The LED chip 110 of the package 109 is positioned on its support substrate in relation to... Figure 23a The arrangement of LED chips 110 (in) Figure 24a (Not visible in the middle) at the same location on its substantially identical support substrate 118, and Figure 24a Lens 112a is directly mounted on the light-emitting surface of the bare die of the light-emitting diode. It should be understood that... Figure 24a The bare die of the light-emitting diode in package 109 is close to the second cut-off portion 116.

[0221] Figure 42a Another example of the HE-LED package 109 is shown. For example... Figure 24a Example, Figure 42a The package 109 includes a bare LED die or chip (not shown) and a cylindrical lens 112. Figure 42a The LED chip in package 109 is positioned on its support substrate 118 in relation to Figure 23a The LED chips 110 are arranged in the same position on their supporting substrate 118. However, in Figure 42aIn the example, the cylindrical lens 112 takes the form of a truncated aspherical lens 112b. Specifically, the cylindrical lens 112b is formed as an aspherical lens within a modified ellipsoid having two first truncated portions 114 and one second truncated portion 116. The two first truncated portions 114 are perpendicular to the axis A of the modified ellipsoid and are equidistant from the longest radius of the modified ellipsoid. The first two truncated portions 114 are parallel to two axes of the ellipsoid and are parallel to each other. The second truncated portion 116 is parallel to the other axis A of the ellipsoid and perpendicular to the two first truncated portions 114. Figure 42a The lens geometry is achieved by sweeping a horizontal spline path across a vertical axis. Variable It is generated from the radius. For example, from... Figure 42a It can be understood that lens 112b has greater curvature at the center (i.e., at the short first radius of curvature R1) and less curvature on the sides and toward the sides (i.e., at the long second radius of curvature R2). In this example, because the lens surface is farther away on the sides than at the center, less power is needed on average to roughly collimate the diverging light.

[0222] Figure 24b and Figure 42b Showing from Figure 24a and Figure 42a The intensity distribution of light in the horizontal (xz) and vertical (xy) planes of the package 109. From Figure 24b and Figure 42b Understandable. Figure 42a The package 109 using the aspherical lens 112b provides a higher performance than... Figure 24a The package 109 using the flattened ellipsoidal lens 112a has a narrower horizontal light distribution. Therefore, it should be understood that the choice of lens 112 can affect the angular distribution of light from the package 109.

[0223] Figure 25a and Figure 25b Show Figure 24a HE-LED package 109 and similar Figure 18a The combination of the geometry of the pocket-type optics 74. Figure 25c The HE-LED lens 112 is shown to capture the full wavelength of light from the LED die, which forms an arc of approximately 180° with the die in the horizontal plane, thus improving optical coupling efficiency. Figure 25d The image shows the intensity distribution of light from the light source 12 within the light guide 10 in the effective region 48 of the thinner region of the light guide 10. This more efficient capture of available light from the LED die results in less stray light being suppressed and processed in the system.

[0224] Figure 26 Showing with, for example Figure 7"soft edges" and smoother HE-LED intensity profiles significantly reduce the distance from the pocket-shoot optics 74 in the forward or z-direction to achieve the 10% uniformity target (indicated by line 119 in Figure 26 In other words, using HE-LED packages 109 allows for a more uniform light intensity profile to be achieved closer to the pocket-shoot optics 74 in the light guide 10. In Figure 7 In the arrangement of the prior art that does not utilize HE-LED packages 109, the intensity profile is discontinuous and requires a greater length of the light guide 10 to achieve the same light intensity uniformity.

[0225] Figure 27 shows how HE-LED light power is scalable by increasing LED die size along the horizontal axis without adversely affecting HE-LED 109 angular distribution characteristics.

[0226] It has been shown how light can be delivered into the light guide 10, for example, the top plate 10 of the device in Figure 1 Next, the management of light in the light guide 10 is discussed. In particular, how light is artfully managed in the light guide 10 to control where light can or cannot reach is discussed.

[0227] One approach for the management of light in the light guide 10 is to use a distributed pattern of light shoot "points" to create the active area of the touch screen, i.e., the active area.

[0228] Another approach is to use light absorbing features (e.g., paint, over-molding, in-mold labeling (IML)) to limit the angular range of light rays or isolate optical geometry elements and control those inactive areas, i.e., provide optically inactive areas.

[0229] Considering the first approach, an "active area" can be created by placing one or more pocket-shoot optics 74 in a pattern around a given light guide geometry. In different embodiments, the pocket-shoot optics 74 can be combined in different patterns or array configurations (e.g., square, rectangular, circular, and many other variants) to efficiently and uniformly distribute light across the active area. For example, referring to Figure 16 A circular array of wide-angle pocket-shoot optics 74a can be used to create a first active area 120 to illuminate a D-pad (i.e., a D-pad) geometry. In the vicinity on the same light guide 10, a second active area 122 can be created using a pair of narrow-angle pocket-shoot optics 74b disposed at either end of a touch area that defines a single slider geometry.

[0230] The key factors for optimizing the patterned light distribution in the active area are: • The inherent pocket-injection optic intensity profile (which can be fixed); • The pattern used to place the pocket-injection optics 74; • The spacing of the pocket-injection optics 74 in the pattern; and • The orientation of the pocket-injection optics 74.

[0231] The same optical targets (as previously described) apply to the active area; that is: • Efficiency maximizes the light power delivered into the active area; • Optimizes optical uniformity as close as possible to the target percentage range; • Minimizes the distance from the pocket-injection optics 74 to the edge of the touch sensitive area (i.e., to the area where target uniformity is achieved); • Using the minimum number of pocket-injection optics 74 leaves more room for other components in the assembly and minimizes electrical power consumption.

[0232] An example of active area creation using a multi-pocket-injection optic 74 layout geometry will now be discussed.

[0233] Figure 28 A circular 3D "carousel" light guide geometry is shown, which utilizes multiple pocket-injection optics 74 (only one of which is labeled in Figure 28 for clarity) to couple light into the light guide 10. Figure 28 The outer shape of the carousel light guide 10 has a curved profile that can form the top plate of a similar dual-plate arrangement as Figure 1

[0234] Figure 28 The light guide 10 has an upper wall 124, a side wall 126, and a lower wall 128. The upper wall 124 defines a central region of the light guide 10 that is substantially planar and generally circular in plan view. The side wall 126 extends downward and radially outward from a circumferential edge 130 of the upper wall 124 to the lower wall 128.

[0235] Light is injected into the light guide 10 from multiple light sources 12 (only one of which is shown in Figure 28 for clarity) disposed in multiple light source cavities 30 (only one of which is labeled in Figure 28 for clarity) in the light guide 10. Each light source 12 is located at a circumferential edge portion 132 of the light guide 10 and undergoes total internal reflection in the light guide 10.

[0236] In this example, the light guide 10 includes sixteen light source cavities 30, each of which receives and encloses a single light source 12. It will be appreciated that more or fewer light sources 12 and associated light source cavities 30 are possible in other examples.​

[0237] Each light source cavity 30 in this example utilizes Figure 7 The geometry of the pocket-type optics 74 is shown. Figure 7 In this arrangement, each light source cavity 30 is defined by a recess in the lower side of the light guide 10 and is disposed within the thicker section 46 of the light guide 10. A ramp section 50 of the light guide 10 combines the thicker section 46 of the light guide 10, including the light source cavity 30, with a thinner section 48 of the light guide 10. In this manner, the sidewall 126 and upper wall 124 of the light guide 10 define the thinner section 48 of the light guide 10, and the lower wall 128 defines the thicker section 46 and the ramp section 50 of the light guide 10.

[0238] Light sources 12 and associated light source cavities 30 are spaced apart at equal intervals around the circumferential edge portion 132 of the light guide 10. Each light source 12 is arranged to face inward toward the central axis C of the light guide 10, such that each light source 12 emits light toward the central axis C.

[0239] Figure 28 The arrangement provides a touch detection area 134, i.e., an effective area or region, for the light guide 10 when it is combined with a suitable touch detection arrangement (e.g., similar to...). Figure 1 In a double-plate arrangement, touch on the light guide 10 can be detected. Figure 28 In the example, the touch detection area 134 is defined by the sidewalls 126 and upper wall 124 of the light guide 10 in this embodiment. However, in other embodiments, the effective area 134 may also surround at least a portion of the lower wall 128 of the light guide 10. Regardless, the light source 12 of the light guide 10 is positioned around the perimeter 136 of the effective area or region 134, which in this example defines a circle in a plan view. In other examples, the shape of the perimeter 136 may vary and may define an ellipse, rectangle, or square in a plan view; these are merely a few non-limiting examples. The light sources 12 are spaced apart to form a substantially uniform light distribution in the effective area 134 of the top plate 10. Figures 29a to 29b Figure 29d Shown in having with Figure 28 The uniformity of light within the similarly arranged turntable light guide 10. Specifically, Figure 29a shows... Figure 28 The light guide 10 includes sixteen light sources 12 (not visible in Figure 29a), and Figure 29b shows the connection with... Figure 28 The light guide is similar to the light guide 10, but includes twelve instead of sixteen equally spaced light sources 12, and Figure 29c Showing with Figure 28 A similar light guide 10, but comprising eight instead of sixteen equally spaced light sources 12. (See Figures 29a to...) Figure 29cIn the diagram, the brighter and darker portions of the light guide 10 represent the irradiance within the light guide 10, with the brighter portions representing higher irradiance and the darker portions representing lower irradiance. (See Figure 29a to...) Figure 29c As can be understood, the light irradiance within the light guide 10 is generally non-uniform within the lower wall 128 of the light guide 10, which includes alternating bright and dark areas (related to the spacing between the light sources 12).

[0240] Figure 29d Figures 29a to 29b show different angular positions around the central axis C of the optical guide 10. Figure 29c The uniformity of optical power density in the sidewalls 126 of each optical guide 10. Figure 29d In the diagram, curve 138 represents the optical guide arrangement in Figure 29a, curve 140 represents the optical guide arrangement in Figure 29b, and curve 142 represents... Figure 29c The optical guide arrangement. Lines 144 and 146 represent the upper and lower limits, within which the optical power density falls within a range of plus or minus 10%. Taking this into consideration, from... Figure 29d It will be recognized that the arrangements of Figures 29a and 29b provide + / - 10% uniformity of light power density within the sidewall 126, while using fewer light sources 12 for illumination. Figure 29c The arrangement of the elements does not fall within the uniformity range at any location across the sidewall 126.

[0241] Turn now Figure 30 Using multiple pocket-type optics 74 (in) Figure 30 Another example of creating an effective area (marking only one of them) is this time in a rectangular flat light guide plate 10. With Figure 28 The same as the optical guide 10. Figure 30 Optical guides can be combined with the use of Figure 1 The basic technology is based on the double-plate layout.

[0242] Figure 30 The light guide 10 is a substantially flat plate with a rectangular shape in the plan view, defined by two long side edges 150 combined with two short side edges 148. In this example, the short side edges 148 of the light guide 10 have a length of 150 mm, and in this example, the long side edges 150 of the light guide 10 have a length of 210 mm; however, it should be understood that these dimensions may vary in other examples.

[0243] Figure 30 The optical guide 10 includes, for example, Figure 7 Multiple pocket-type optical devices 74 are shown. The light source cavity 30 of the pocket-type optical devices 74 is disposed along the edge portions 154, 156 of the light guide 10. Figure 30In this example, the light guide 10 includes six light source cavities 30 along each short-side edge portion 154 of the light guide 10, and ten light source cavities 30 along each long-side edge portion 156 of the light guide 10. Therefore, in this example, the light guide 10 includes thirty-two light source cavities 30, and thirty-two associated light sources 12 (i.e., thirty-two pocket-entry optics 74) disposed in the light source cavities 30 during use. It should be understood that in other examples, the light guide 10 may include more or fewer pocket-entry optics 74.

[0244] like Figure 7 The arrangement is such that each pocket-type optic 74 is disposed in the thicker section 46 of the light guide 10. A ramp section 50 of the light guide 10 connects the thicker section 46 to a thinner section 48 of the light guide 10. In this example, the thinner section 48 of the light guide 10 defines a central region with a rectangular shape in a plan view of the light guide 10. The thinner section 48 defines an effective area or region 134 of the light guide 10, wherein a touch on the light guide 10 can be detected when the light guide 10 is integrated with a suitable touch detection device, such as a [missing information - likely a device for detecting touches]. Figure 1 A similar dual-plate device.

[0245] Figures 31a to 31d Showing with Figure 30 The uniformity of light within a similarly arranged rectangular light guide 10. Specifically, Figure 31a Show Figure 30 The light guide 10 includes thirty-two pocket-type optics 74 (in Figure 31a (Not visible in the middle) Figure 31b Showing with Figure 30 A similar light guide 10, but it includes twenty-six pocket-type incident optics 74, and Figure 31c Showing with Figure 30 A similar light guide 10, but it includes twenty pocket-type optics 74. (See Figures 29a to 29b). Figure 29c similar, Figures 31a to 31c The brighter and darker portions of the light guide 10 represent the intensity distribution of light within the light guide 10, where the brighter portions represent higher intensity and the darker portions represent lower intensity.

[0246] Figure 31d Shown in Figures 31a to 31c In each optical guide, the optical power density is along the central axis, especially... Figure 30 The uniformity on the x-axis is shown. Lines 158 and 160 represent the upper and lower limits, within which the optical power density falls within a range of plus or minus 10%. Figure 31d In the middle, curve 159 represents Figure 31a The optical guide arrangement, represented by curve 161. Figure 31b The optical guide arrangement, and curve 163 indicatesFigure 31c The light guide arrangement of FIG. 1. With this in mind, it can be understood from Figure 31d that Figures 31a to 31c The arrangements of FIGS. 1, 2, and 3 all provide + / - 10% light power density uniformity within the central region of the light guide 10.

[0247] The concept of optically inactive zones will now be described in more detail. Optically inactive zones can be formed by using light absorbing elements, light absorbing layers, or light absorbing coatings 58 on the light guide 10. The light absorbing layers or elements 58 can be used to isolate independent optical geometries in one region of the light guide 10. The light absorbing layers or elements 58 can additionally or alternatively be used to prevent light from one region of the light guide 10 from interfering with light from another region of the light guide 10 to avoid unwanted light leakage from the light guide 10. In general, the layers or coatings 58 disposed on one or more regions of the first surface 23 of the light guide 10, the second surface 25 of the light guide 10, or both can be used to suppress internal reflections at that region of the relevant surface 23, 25 to provide optical separation between one portion of the ceiling tile 10 and another portion of the ceiling tile 10.

[0248] Referring to Figure 32 , a light guide 10 is shown having two optically active zones 162 separated by optically inactive zones 164. Figure 32 The light guide 10 of FIG. 1 uses a first trench-injection optic 52a to couple light into the first active zone 162a and a second trench-injection optic 52b to couple light into the second active zone 162b. The first active zone 162a defines a wedge-shaped geometry having upward and downward sloping portions 166. The second active zone 162b defines a slider geometry. It should be understood that in other examples, the light guide 10 can incorporate more or fewer active zones 162 and that the active zones 162 can define other geometries, such as a carousel, etc. Further, other trench-injection optic 52 geometries or pocket-injection optic 74 geometries can be used to illuminate the active zones 162 of the light guide 10. Further, light sources 12 having different properties can be used to illuminate different active zones 162 of the light guide 10.

[0249] Light is injected into the first active zone 162a at a narrow vertical angular range to minimize losses. However, the angular range of the injected light from the first trench-injection optic 52a can widen after passing through the wedge-shaped geometry of the first active zone 162a. In examples such as Figure 32In the illustrated light guide 10 without an inactive region 164, if light from the first trench-injection optic 52a is allowed to continue into the second active region 162b after passing through the first active region 162a, and pass through the slider geometry in the second active region 162b, the angular range of the injected light can be further widened, such that some light rays can fall below the critical angle limit at the upper surface 23 or lower surface 25 of the light guide 10 (i.e., outside the angular range that experiences total internal reflection at one of these surfaces 23, 25) and be lost from the light guide 10. As Figure 32 As illustrated, an optical absorption band 168 is added to the underside of the light guide 10 between the first active region 162a and the second active region 162b, creating an inactive region 164 that isolates the first active region 162a from the second active region 162b.

[0250] Turning now to Figure 33 Another example of a light guide 10 uses a single absorption inactive region 170 to isolate multiple active regions 172. An absorption mask layer 174 having multiple openings is disposed on the upper surface 23 of the light guide 10 to define multiple active regions 172 of the light guide 10. Specifically, the active regions 172 of the light guide 10 in which touch detection can occur are defined in the openings 176 of the absorption mask layer 174.

[0251] The mask layer 174 can comprise, for example, black paint or any other suitable opaque paint or material. In some examples, the mask layer 174 can be formed by overmolding or using IML. As previously mentioned, the mask layer 174 can be opaque to “working” light, but transparent to other light, such as visible light in the case where the device is configured to operate in the infrared.

[0252] Inactive regions can use various light absorption methods to control or prevent these light losses, i.e., the loss of light injected from the light guide 10. Table 1 below summarizes the advantages and disadvantages of three known light absorption methods (i.e., using paint, overmolding, or IML).

[0253] · Table 1. Different absorption methods for area isolation

[0254] Examples using region isolation will now be described.

[0255] Figure 34a and Figure 34b An example of end region isolation in a symmetric light guide 10 is illustrated, in which an absorption coating 178 is provided at some or all of the periphery of the top plate 10. A first trench-injection optic 52a is positioned toward or near a first end 180 of the light guide 10, and a second trench-injection optic 52b is positioned at an opposite second end 182 of the light guide 10.

[0256] InFigure 34a In this arrangement, an absorber is provided on the end face of the light guide 10 to prevent light from escaping from the light guide 10 through the end face. In this example, an absorber 178 is provided on the second end face 184 at the second end 182 of the light guide 10, and absorbs the light entering the light guide 10 from the first incident optical device 52a at the first end 180 of the light guide 10, and prevents the light from leaving the light guide 10 through the second end face 184. In some examples, an absorber 178 may be provided on the first end face 186 at the first end 180 of the light guide 10 to prevent light from escaping from the light guide 10 through the first end face 186, particularly to prevent light from escaping from the second trench incident optical device 52b.

[0257] exist Figure 34b In this arrangement, an absorber 178 is provided along a portion of the end wall of the light guide 10 to prevent light from escaping from the light guide 10 through the end wall. In this example, an absorber 178 is provided on the upper surface 23 of the light guide 10 along the second end wall portion 188 at the second end 182 of the light guide 10, such that light incident from the first incident optical device 52a into the light guide 10 is absorbed and blocked, preventing it from leaving the light guide 10 through the second end wall portion 188 and preventing the light from continuing to travel in the light guide 10. In some examples, an absorber 178 may be provided on the first end wall portion 190 at the first end 180 of the light guide 10 to prevent light from escaping from the light guide 10 through the first end wall portion 190, particularly preventing light from escaping from the second trench incident optical device 52b, and preventing it from continuing to travel in the light guide 10. Although in Figure 34b In the arrangement, the absorber 178 is disposed on the upper surface 23 of the light guide 10, but it should be noted that in some examples, the absorber 178 may be additionally or alternatively disposed on the lower surface 25 of the light guide 10.

[0258] In some examples, the absorber 178 may be disposed on the end face and end wall portions as needed.

[0259] In this way, light traveling from one end of the light guide 10 to the other end is absorbed at one or more end faces and / or end walls to prevent the light from escaping from the light guide 10 as stray light.

[0260] like Figure 35a As shown, light from the first trench incident optics 52a can pass through the light guide 10 and be reflected upwards by total internal reflection, exiting the input wall (i.e., the optical coupling wall 36) of the second trench incident optics 52b. This light reflected at the optical coupling wall 36 of the second trench incident optics may escape from the light guide 10 as stray light through the upper surface 23 of the light guide 10. Figure 35bAn absorber 178 is shown disposed on the upper surface 23 of the light guide 10 to absorb and block the escape of stray light reflected from the light coupling surface 36. To this end, the absorber 178 extends over and across the second in-coupling optic 52b and its light coupling wall 36. It should be noted that in some examples, an absorber 178 can additionally or alternatively be disposed to the lower surface 25 of the light guide for this purpose. For example, an absorber 178 disposed on the lower surface 25 of the light guide 10 forward of the second in-coupling optic 52b (i.e., away from the second end 182 of the light guide 10 and toward the center of the light guide) can absorb light from the first in-coupling optic 52a before it can reach the second in-coupling optic 52b. Similarly, the same is true for an absorber 178 extending on the upper surface 23 of the light guide 10 forward of the second in-coupling optic 52b.

[0261] As mentioned previously, the role of the absorber can be more complex, as different properties can be required at different wavelengths. In some cases, the absorbers discussed above, for example in the separation active regions, can be absorbing at the operating wavelength, but transmitting at other wavelengths. This allows a device configured to detect in the infrared to have "masked" regions in the visible light region for the separation active regions, for example, through these separation regions, a display disposed behind the touch screen can be seen.

[0262] In some examples, the absorber can be used for aesthetic masking of the sub-surface optics and components of the light guide 10 to improve the aesthetics of the arrangement, or to simplify the appearance of the device to a user. In this regard, it is useful to add an opaque tint to the light guide 10 that absorbs at visible wavelengths, but transmits at the near-infrared (NIR) wavelengths used by the light source 12 (e.g., LED light source 12), which is arranged in opposition to the arrangement just discussed above, where the opacity is present at the operating wavelength, rather than at the visible wavelengths. Such an opaque tint can be used, for example, to hide the in-coupling grooves 52 or pocket in-coupling optics 74 or any other components beneath the light guide 10 from the perspective of a user, while allowing NIR light from the light source(s) 12 to propagate in the light guide 10 unimpeded by absorption.

[0263] As mentioned above, the light guide 10 can be incorporated into a three-layer optical laminate such as Figure 1 to provide the touch sensitive device 8, and the three-layer optical laminate can be positioned over a display to form the touch sensitive device 8.

[0264] In this arrangement, the laminated upper layer 10 and lower layer 18 can be referred to as the transmit (Tx) and receive (Rx) layers, respectively. The upper layer 10 and lower layer 18 are separated by the middle layer 14, which can comprise air or an optical material having a lower refractive index than the upper layer 10 and lower layer 18 (referred to as a cladding layer). When the middle layer 14 comprises an optical material, the optical material defines a layer of optically transmissive material.

[0265] The trench-injection optical device 52 and pocket-injection optical device 74 structures that have been discussed can be prototyped using a combination of standard machine polishing of acrylic or vacuum casting techniques, which are more suitable for small batch manufacturing. However, the use of trench or pocket-injection optical devices 52, 74 in the upper transmissive layer 10 of this system enables the use of new construction methods that allow for medium to large batch manufacturing. For example, injection molding techniques can be used to produce the laminated structure to combine some or all of the following optical elements and features together: light injection, active and inactive areas, light detection, decorative effects, and display elements. This provides the following main advantages: minimum form factor, lower part count, ease of assembly, improved transmission, aesthetics, and ultimately lower overall manufacturing and assembly costs. All of these can be designed to use surface mount electronic components, again minimizing form factor and simplifying assembly.

[0266] As has been discussed, various schemes can be employed in the light guide 10 to absorb unwanted light, such as to prevent these lights from escaping through the top 34 of the trench or pocket-injection optical device cavities 52, 74 (see, for example, Figure 10 and Figure 19 ), or to prevent light from one active area from passing into another active area (see, for example, Figures 32 to 3 5). Such schemes using masking techniques allow for regions of the light guide 10, and in particular the first surface 23 of the light guide 10, to be isolated from any other optical activity in the light guide 10.

[0267] For example, a paint having an appropriate absorption spectrum that matches one or more of the light sources 12 can be used to block light from reaching different surfaces and regions of the light guide 10. However, the use of paint for this purpose involves a secondary process. In this secondary process, the placement of the paint can not always be precisely controlled, and the application of the paint is not cost effective for large batches.

[0268] The over-molding or in-mold labeling (IML) / in-mold decoration (IMD) process allows for the absorption ink to be placed in the mold in the form of a thin secondary layer, and both provide an attractive alternative to the above. These manufacturing techniques allow for the creation of regions on the touch surface (i.e., the top plate or the upper surface of the light guide) that can incorporate an absorption mask to (a) hide components or features underneath the top plate 10 in line of sight, (b) optically isolate one region from another, or (c) provide a decorative effect, as well as combinations of these effects (a) through (c). Once the molding process is set, the manufacturing method provides a solution for mass production of large batches of upper or transmissive layers 10 with precise and effective stray light control.

[0269] IML (versus over-molding) has the distinct advantage of being able to achieve attractive decorative effects, which can make the surface look like many different materials (e.g., fabric, carbon fiber, or leather). Typically, the LEDs 12 used for the channel and pocket shoot-in optics 52, 74 emit in the near-infrared (NIR) region of the light spectrum. The inks used in the IML can be selected to absorb light over the visible spectrum (i.e., 400-800 nm) and used to produce the decorative effects. The same inks are selected so that they do not absorb the NIR light from the LEDs 12 and do not interfere with the touch detection process. The embodiments described in detail herein outline the use of acrylic material (e.g., poly(methyl methacrylate) or PMMA) sheet, but it should be noted that other types of 3-layer systems can be used, for example, a glass layer can be used as a substitute for the acrylic layers. However, the manufacturing techniques discussed here are particularly well suited for acrylic top and bottom layers.

[0270] Table 2 shows a comparison of the absorption mask manufacturing process using over-molding or IML / IMD: Table 2. Comparison of absorption mask manufacturing processes using overmolding or IML / IMD

[0271] With respect to the overall wall section thickness range of Table 2, it should be noted that these values are those that are considered to be good practice for standard mass production.

[0272] Referring again to FIGS. 8A and 8B, replacing the intermediate air layer 14 in the 3-layer system comprising an acrylic upper layer and an acrylic lower layer with a higher refractive index material layer reduces the critical ray angle at the boundary (i.e., the angle between the light ray and the surface boundary from about 48° to 26°). Thus, using a higher refractive index middle layer in place of the intermediate air layer requires a more restricted range of angles in the light guide 10 for substantially all of the light to experience total internal reflection at the boundary.

[0273] However, using a cladding layer in a 3 layer laminate instead of a 1 mm air gap advantageously enables the total laminate thickness to be reduced. In order to provide this advantage, while also maintaining as wide an angular range as possible over which light experiences total internal reflection at the boundaries between the upper and lower layers and the cladding layer, the cladding layer is selected to be of a material having a low refractive index as close as possible to that of air. In some examples, the cladding layer can take the form of an intermediate FEP layer, although other materials are possible.

[0274] Using a low refractive index middle layer instead of an air gap reduces Fresnel reflections at the boundary between the upper (transmission) layer and the middle layer, and at the boundary between the lower (receiving) layer 18 and the middle layer 14. This improves the overall transmission and transparency of the laminate. Furthermore, using a low refractive index middle layer instead of an air gap for the laminate structure improves the robustness of the manufactured assembly.

[0275] A disadvantage of using a low refractive index middle layer 14 instead of an air gap is a reduction in the evanescent field strength due to shallower average light ray reflection angles. Furthermore, a laminate using a low refractive index middle layer 14 instead of air provides lower light coupling efficiency due to the need to reduce the angular range of total internal reflection.

[0276] Manufacturing scheme embodiments will now be discussed showing how a low refractive index middle layer can be combined with a secondary forming or in-mould marking.

[0277] Figure 36 A touch sensitive device formed from a composite material 192 is shown. The composite material 192 comprises an upper (transmission) layer 10 in the form of an optically clear sheet defining a touch surface 23 of the device. The composite material 192 also comprises a lower (receiving) layer 18 in the form of a further optically clear sheet, and a middle layer 14 defined by an air gap between the upper layer 10 and the lower layer 18. The upper layer 10 comprises a channel-injection optical 52 comprising an array of light sources 12 disposed in light source cavities 30 of the channel-injection optical 52 (in this case, only one of which can be seen). It will be appreciated that one or more pocket-injection optical devices 74 can be incorporated in the arrangement of Figure 36 Figure 36 instead of, or in addition to, the channel-injection optical device 52.

[0278] ​In this example, the light sources 12 are LEDs operating in the near infrared (NIR) region of the optical spectrum. The device includes a single printed circuit board (PCB) 54 on which the light sources 12 are mounted, and a mechanical frame or holder 194 holds the upper layer 10 and lower layer 18 on either side of the PCB 54. An ethylene vinyl acetate (EVA) foam gasket 196 is inserted between the upper layer 10 and lower layer 18 to create or provide the air gaps 14 and hold them apart from each other. In this way, the lower layer or substrate 18 is mounted relative to the upper layer or top plate 10 such that if an external body touches the first surface 23 of the top plate 10, light is coupled into the substrate 10 from the second surface 25 of the top plate 10 through the first or upper surface of the substrate 10. Another EVA gasket 198 is inserted between the lower layer 18 and the display 200, and also forms part of the composite material 192, to create the air gap 202 and hold the lower layer 18 and display 200 apart from each other.

[0279] An acetate film is added to the upper layer or lower layer contact points (i.e. the contact areas between the upper layer 10 and other components, and between the lower layer 18 and other components) to prevent the upper layer 10 and lower layer 18 from “wetting out” and causing the constrained light to leak. The upper layer 10 is injection molded with an IML in the insert tool to allow a border, graphic, or textured effect to be added to a portion of the upper surface 23 of the upper layer 10 without completely covering the underlying display 200. Furthermore, a thin layer of material 204 is printed on the underside of the IML film 203 that is transparent to light in the near infrared region of the optical spectrum, but absorbs light in the visible region of the optical spectrum. In this way, the LEDs 12 underneath the layer 204 are masked from view by the user, while still allowing the NIR light emitted by the LEDs 12 to be totally internally reflected from the upper surface 23 of the upper layer 10. Similar to the arrangement of Figure 3 , the separate opaque layer portions 206, i.e. light absorbing elements, disposed on the upper surface 32 and rear surface 38 of the light source cavity 30 between the light sources 12 and the first surface of the light guide 10, define the light source apertures 56 in the arrangement of Figure 36 that limit the angular range of light coupled into the upper layer light guide 10 emitted by the LEDs 12.

[0280] An alternative masking arrangement is possible. In one alternative masking arrangement (not shown), the opaque near infrared absorbing coating 206 disposed over the light sources in the cavity 30 in the arrangement of Figure 36 may be omitted, and the light source apertures 56 can instead be defined by the upper surface IML film arrangement. Specifically, a portion of the upper surface IML film arrangement over the cavity 30 can be absorbing in the near infrared region of the optical spectrum in order to mimic the absorbing coating 206 of the arrangement of Figure 36 . In this case, the upper surface IML film arrangement still maintains the visible absorbing decorative effect as previously in the arrangement of Figure 36 .

[0281] Sensors in the form of light detectors 20 are positioned as needed at the edges of the lower layer 18 for detecting light coupled from the upper layer 10 into the lower layer 18 in response to touches on the upper surface 23 of the upper layer 10.

[0282] Figure 37 Another composite material device 192 is shown using a single PCB 54 (i.e., similar to Figure 36 ). Figure 37 The device of includes an additional IML film 208 that provides similar functionality to the layer that defines the light source aperture 56 in Figure 36 . Thus, Figure 37 The arrangement of does not include the opaque layer portions 206 disposed on the top surface 32 and back surface 38 of the light source cavity 30 because the additional IML film 208 replaces that element. In particular, the additional IML film 208 has an opaque layer 210 that functions to limit the angular range of light coupled from the LEDs 12 into the upper layer 10. This provides a single, laminated upper layer optical component to improve ease of assembly.

[0283] Similar to the discussion regarding Figure 36 , alternative masking devices (not shown) can also be used here. For example, one possible alternative masking device can omit the additional IML film 208 and use a different upper surface IML film device configured to absorb the near infrared region in the appropriate region above the light sources 12 to define the light source aperture 56. In that case, the upper surface IML film arrangement can still maintain the visible absorption decorative effect as before in the arrangement of Figure 36 .

[0284] Figure 38 A touch sensitive device is shown formed from a laminate 212. The laminate 212 includes an upper layer 10 defining an optical light transmissive sheet, a lower layer 18 defining another optical light transmissive sheet, and an intermediate optical layer 14 in the form of a low index mid-layer between the upper layer 10 and the lower layer 18. In this example, the low index mid-layer 14 is a single low index optical adhesive layer that provides optical bonding between the optical light transmissive sheets 10, 18. In other examples, the mid-layer can take different suitable forms. For example, in some examples, the mid-layer can be formed from a stack of sub-layers.

[0285] Figure 43 An example of a mid-layer 14a formed from a stack of sub-layers is shown. The mid-layer 14a includes upper and lower optically clear adhesive film layers 213 bonded to the upper layer 10 and the lower layer 18, respectively. The mid-layer 14a also includes two polycarbonate layers 215 and a central low index adhesive layer 217. In Figure 43In the example of FIG. 21, the upper and lower adhesive layers 213 each have a thickness of 0.25 mm, the polycarbonate layers 215 each have a thickness of 0.1 mm, and the central low refractive index adhesive layer 217 has a thickness of about 5 pm. In other examples, the materials and forms of the sub-layers can be different, and in particular, the number and thickness of the stacked sub-layers can vary.

[0286] Returning to Figure 38 , the laminate 212 also includes the display 200 positioned below the lower layer 18, and an additional low refractive index layer 214 disposed between the lower layer 18 and the display 200. As with Figure 36 and Figure 37 , the arrangement of Figure 38 includes a single PCB 54.

[0287] It will be appreciated that, in contrast to the arrangement of Figure 36 and Figure 37 , the air layers between the upper layer 10 and the lower layer 18 and between the lower layer 18 and the display 200 have been replaced by low refractive index layers 14, 214. The low refractive index layers 14, 214 are optically bonded to the upper layer 10 and the lower layer 18 by optical bonding layers. This requires increased manufacturing complexity, but provides a single, laminated optical component for simpler assembly.

[0288] As in the arrangement of Figure 36 , the separate opaque layer portions 206 positioned at the upper and rear positions within the light source cavity 30 define Figure 38 the arrangement of , which limits the angular range of light emitted by the LEDs 12 that is coupled into the upper layer light guide 10. As previously mentioned, in embodiments, this opaque layer portion 206 can be opaque only in the “working” near infrared range, and can in fact be transparent in part or all of the visible spectrum. Also as in the arrangement of Figure 36 , a thin layer of material 204 that is transparent to light in the near infrared region of the spectrum but absorbs light in the visible region of the spectrum is printed onto the underside of the IML film 203. The layer 204 is formed during the molding of the laminate. Figure 38 The arrangement of also includes an absorbing structure 218 arranged to block light that is not desired to undergo total internal reflection and continue to propagate in the light guide 10.

[0289] It will be appreciated that Figure 38 the upper layer 10 of the arrangement of has a ramped wedge portion 50 between the thicker portion 46 of the light guide 10 that includes the channel-injection optical feature 52 and the thinner portion 48 of the light guide 10 that defines the active area of the light guide 10 in which touches can be detected.

[0290] Figure 39 FIG. 22 shows the use of the laminate 212 (similar toFigure 38 another touch sensitive device formed by the laminate. Figure 39 Many features of the device of Figure 38 the arrangement of FIG. 1 are the same as features of the arrangement of Figure 38 In comparison to the arrangement of Figure 39 The arrangement of FIG. 2 includes an additional IML film 220 on the lower surface of the upper layer 10, positioned to extend across the back surface 38 and the upper surface 32 of the light source cavity 30, which provides a separate opaque layer portion 206 defining the light source aperture 56 in Figure 38 The additional IML film 220 serves to control the angular range of light from the LEDs 12 that is coupled into the upper layer 10. Note that, as in the arrangement of Figure 36 In the arrangement of FIG. 2, a thin layer of material 204 that is transparent to light in the near infrared region of the spectrum but absorbs light in the visible region of the spectrum is printed onto the underside of the IML film 203 in the arrangement of FIG. 1. The layer 204 is formed during molding of the laminate. Figure 39

[0291] It should be noted that alternative masking arrangements are possible, in one such alternative masking arrangement (not shown), the additional IML 220 over the LEDs 12 can be omitted, and a different upper surface IML film arrangement configured to absorb the near infrared region in the appropriate region over the light sources 12 to define the light source aperture 56 can be used. In this case, the upper surface IML film arrangement can still maintain a visible absorption decorative effect, as previously described.

[0292] From the above discussion, it can be appreciated that by combining the light injection, light distribution, and light isolation manufacturing elements into a laminate structure, they can be combined together using injection molding techniques. One or more light absorbing layers can be replaced with in-mold labeling (IML), and the air gap between the upper and lower layers can be replaced with a low index of refraction layer such as FEP.

[0293] Those skilled in the art will understand that the application can be modified in a number of alternative forms described herein without departing from the scope of the accompanying claims.​

Claims

1. A touch-sensitive device comprising: A top plate having multiple light sources associated therewith, such that light from the multiple light sources is transmitted within the top plate by total internal reflection; as well as A substrate having one or more detectors associated therewith for detecting light transmitted within the substrate; The top plate and the substrate are configured such that if an external body touches the first surface of the top plate, light is coupled from the second surface of the top plate through the first surface of the substrate into the substrate. The plurality of light sources are disposed within a linearly extending recess in the second surface of the top plate, such that light from the plurality of light sources is coupled into the top plate through the wall of the recess, and the plurality of light sources form a linear array within the linearly extending recess.

2. The touch-sensitive device according to claim 1, wherein the linearly extending recess extends in a straight line.

3. The touch-sensitive device according to claim 1, wherein the linearly extending recess extends along a curve.

4. The touch-sensitive device according to any one of the preceding claims, wherein the wall of the recess forms an angle with the plane of the top plate, such that the wall and the second surface of the top plate form an obtuse angle within the top plate.

5. The touch-sensitive device according to any one of the preceding claims, wherein the mounting of the light source relative to the refractive surface or the wall of each refractive surface increases the evanescent field intensity of the refracted light, while confining the light within the top plate by total internal reflection.

6. The touch-sensitive device according to any one of the preceding claims, wherein the wall of the recess is provided with a lens.

7. The touch-sensitive device according to any one of the preceding claims, wherein each of the light sources is mounted at an angle to the plane of the top plate such that light emitted from each light source is primarily obliquely directed toward the first surface.

8. The touch-sensitive device according to any one of claims 4 to 7, wherein each of the plurality of light sources is mounted such that the light emitted therefrom is directed primarily at an angle toward the wall of the recess.

9. The touch-sensitive device according to any one of the preceding claims, wherein the top plate further includes a width-reducing section in which the distance between the first surface and the second surface is substantially constant, but less than the distance between the first surface and the second surface at the recess.

10. The touch-sensitive device of claim 9, wherein the top plate further includes a ramp section in which the distance between the first surface and the second surface of the top plate is reduced, the ramp section being located between the recess and the width-reducing section.

11. The touch-sensitive device according to claim 10, wherein the ramp section gradually tapers linearly.

12. The touch-sensitive device according to claim 10, wherein the ramp section gradually tapers non-linearly.

13. The touch-sensitive device according to any one of the preceding claims, wherein a region of the first surface is masked to prevent total internal reflection of light from the plurality of light sources in the trench.

14. The touch-sensitive device of claim 13, wherein a section of the first surface located above the recess and extending beyond the recess is provided with a mask to limit the angular range of incident light reflected at the first surface from the plurality of light sources.

15. The touch-sensitive device of claim 14, wherein the masking is provided by a light-absorbing layer disposed on or on the first surface.

16. The touch-sensitive device according to any one of the preceding claims, wherein the area of ​​the recess between the light source and the first surface is masked.

17. The touch-sensitive device of claim 16, wherein the masking is provided by a light-absorbing layer disposed on the surface of the recess or on the surface of the recess.

18. The touch-sensitive device according to claim 16 or 17, wherein the masking is also provided by a light-absorbing element on which the light source is mounted.

19. The touch-sensitive device according to any one of claims 16 to 18, wherein the masking of the region of the recess is defined for emitting light from the light source into an aperture in the top plate.

20. The touch-sensitive device according to any one of the preceding claims, wherein the top plate has a linear protrusion extending on the second surface away from the first surface, wherein the linear extension of the linear protrusion is substantially parallel to the linear extension of the groove.

21. The touch-sensitive device of claim 20, wherein the linear protrusion has a rectangular or fan-shaped cross-section perpendicular to its linear range.

22. The touch-sensitive device according to any one of the preceding claims, wherein an air gap exists between the top plate and the substrate.

23. The touch-sensitive device according to any one of claims 1 to 21, wherein an optically transmissive material layer exists between the top plate and the substrate.

24. The touch-sensitive device according to any one of the preceding claims, wherein the plurality of light sources are spaced apart to form a substantially uniform light distribution in the body of the top plate.

25. The touch-sensitive device according to any one of the preceding claims, wherein each of the plurality of light sources is a light-emitting diode.

26. The touch-sensitive device of claim 25, wherein each light-emitting diode emits light in the near-infrared range.

27. The touch-sensitive device according to any one of the preceding claims, wherein the wall of the recess is configured to limit the range of vertical angles of light propagating in the top plate from the plurality of light sources.

28. The touch-sensitive device according to any one of the preceding claims, wherein the wall of the recess is configured to increase the range of horizontal angles of light incident on the wall of the recess.

29. The touch-sensitive device according to any one of the preceding claims, wherein the emitting area of ​​the light source is positioned at a predetermined distance from the wall of the recess to limit the range of vertical angles of light rays propagating in the top plate from the light source.

30. The touch-sensitive device according to any one of the preceding claims, wherein the range of vertical angles of light rays from the light source propagating in the top plate is limited such that substantially all light rays from the light source coupled into the top plate are confined in the top plate by total internal reflection.

31. The touch-sensitive device according to any one of the preceding claims, wherein one or more of the angle between the wall of the recess and the plane of the top plate, the mounting of the light source relative to the wall of the recess, and the curvature of the wall of the recess are configured to limit the range of vertical angles of light from the light source propagating within the top plate, thereby increasing the evanescent field intensity at the first surface while confining the light within the top plate by total internal reflection.

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