Optical systems

Abstract

A touch sensing device comprising: a top plate having one or more associated light sources; and a base plate having one or more associated detectors for detecting light propagated within the base plate, wherein light from the one or more light sources propagates within the top plate by total internal reflection, and the top plate and the base plate are configured such that when an external object touches a first surface of the top plate, light is coupled to the base plate from a second surface of the top plate through the first surface of the base plate, and each of the one or more light sources is disposed in a recess for the light source within the top plate, the recess having one or more refractive input surfaces, and light from the light source is coupled to the body of the top plate via the one or more refractive input surfaces.

Description

[Technical Field]

[0001] This disclosure relates to optical systems suitable for use in touch-sensitive devices. In particular, it relates to embodiments suitable for use in controllers of electronic human display interfaces (HDIs) (e.g., car center consoles, washing machine control panels, portable game controllers, or other suitable smart controller HDIs). [Background technology]

[0002] Currently, in typical optical touch-sensitive screens, light is injected from light-emitting diode (LED) emitters through the peripheral edges of the plate. While this is easy to implement, it can lead to inefficient optical illumination of specific touch-sensitive areas. This usually occurs because the light intensity weakens as it propagates long distances through the light guide, or because the light is not directed where it is most needed. This optical inefficiency leads to the use of more LED emitters than necessary, increasing power consumption, which is detrimental in systems where power management is critical. [Overview of the project] [Problems that the invention aims to solve]

[0003] The present invention aims to eliminate one or more of the drawbacks of the prior art and provide a touchscreen that is improved in terms of cost and reliability. [Means for solving the problem]

[0004] In a first embodiment, the present invention provides a touch sensing device comprising a top plate associated with one or more light sources, and a base plate having one or more detectors associated for detecting light propagated within the base plate, wherein light from the one or more light sources propagates within the top plate by total internal reflection. The top plate and base plate are configured such that when an external object touches a first surface of the top plate, light is coupled from a second surface of the top plate through the first surface of the base plate to the base plate. Each of the one or more light sources is located in a recess for the light source within the top plate, the recess having one or more refractive input surfaces, and light from the light source is coupled to the body of the top plate through the one or more refractive input surfaces.

[0005] In the case of one or more light sources, the recess may have a central refractive input surface and two side refractive surfaces arranged symmetrically with respect to the central refractive input surface and adjacent to the central refractive input surface.

[0006] The curvature of the central refraction input surface may differ from that of the lateral refraction surfaces. In some embodiments, the central refraction input surface may have a conical curvature. In some embodiments, the central refraction input surface may have an elliptical curvature.

[0007] The wall of the refractive input surface may form an angle with respect to the plane of the top plate, so that the refractive input surface and the second surface of the top plate form an obtuse angle within the top plate.

[0008] The mounting of the light source to the wall of the refraction input surface may be such that it increases the intensity of the evanescent field and refracts the light so that it is confined within the top plate by total internal reflection.

[0009] The wall of the refractive input surface may be made into a lens.

[0010] The light source may be mounted at an angle to the plane of the top plate such that the light emitted from the light source is mainly directed obliquely to the first surface.

[0011] Each light source may be mounted such that the light emitted from the light source is primarily directed obliquely to at least one refractive input surface.

[0012] By changing the mounting angle of the light source relative to the wall of the recess in this way, the intensity of the evanescent field can be increased or adjusted, thereby maximizing or adjusting the responsiveness of the device to touch.

[0013] The top plate may further include a narrow section in which the distance between the first and second surfaces is substantially constant, but smaller than the distance between the first and second surfaces in the recess. The top plate may further include a tapered section in which the distance between the first and second surfaces of the top plate is reduced, and the tapered section is located between the recess and the narrow section.

[0014] The tapered portion may be linearly tapered. The tapered portion may be nonlinearly tapered.

[0015] In some embodiments, an air gap may exist between the top plate and the bottom plate. In other embodiments, a light-transmitting material layer may exist between the top plate and the bottom plate.

[0016] The region of the first surface can be masked to prevent total internal reflection of light from each light source within the recess. By providing the masking on a portion of the first surface located above the recess and extending beyond the recess, the range of incident angles of light reflected by the first surface from multiple light sources can be limited. The masking can be provided by a light-absorbing layer on or provided on the first surface.

[0017] The touch sensing device may have multiple light sources. The masking may extend across two or more of the multiple light sources.

[0018] Masking can define the active area of ​​the top plate, and multiple light sources illuminate the active area of ​​the top plate.

[0019] The plurality of light sources may be arranged on the outer periphery of the active region. The outer periphery of the active region may be rectangular. The outer periphery of the active region may be elliptical.

[0020] The first surface of the top plate within the active region does not have to be flat.

[0021] The plurality of light sources may be arranged at intervals in order to form a substantially uniform light distribution in the active region of the top plate.

[0022] The region of each recess between the light source and the first surface may be masked. The masking may be provided by a light absorption layer provided on or at the surface of the recess.

[0023] The masking may be performed by a light absorption element attached to the light source.

[0024] By masking the region of the recess, an aperture for emitting light from the light source to the top plate can be defined.

[0025] When masking is performed in this way, the proportion of the light from each light source confined within the top plate by total reflection increases. In some embodiments, substantially all of the light that enters the top plate without being absorbed by the masking is confined within the top plate by total reflection. Therefore, the use of the masking increases the proportion of the light confined within the top plate with respect to the light permitted to enter the system for reflection at the first and second surfaces. In this way, stray light from the top plate is advantageously reduced.

[0026] Each of the one or more light sources may be a light emitting diode. Each of the one or more light emitting diodes may emit near infrared light.

[0027] One or more refractive input surfaces may be configured to restrict the vertical angular range of light propagating from the light source through the top plate. One or more refractive input surfaces may be configured or positioned to reduce the vertical angular range of light incident on one or more refractive input surfaces. Restricting the vertical angular range of light propagating through the top plate can increase the proportion of light confined within the top plate by total internal reflection, and consequently decrease the proportion of light emitted from the top plate as stray light.

[0028] One or more refractive input surfaces may be configured to expand the horizontal angular range of light incident on one or more refractive input surfaces. Therefore, the horizontal angular range of light from a light source within the top plate may be greater than the horizontal angular range of light from the light source before it enters the refractive input surface. In this way, the refractive input surfaces allow the incident light to spread horizontally within the top plate. This can lead to a more uniform distribution of light across the entire top plate, improving touch responsiveness. Furthermore, controlling the horizontal spread of light within the top plate in this manner improves the uniformity of light closer to the light source, making it possible to create an effective active region closer to the light source where the device can sense touch.

[0029] The light-emitting region of the light source may be positioned at a predetermined distance from one or more refractive input surfaces to limit the vertical angular range of light rays propagating from the light source through the top plate. In some embodiments, the position of the light source and its light-emitting region relative to one or more refractive input surfaces may be selected such that only a portion of the light rays from the light source are captured and coupled to the top plate via one or more refractive input surfaces. In this way, the vertical angular range of light propagating from the light source to the top plate can be limited, and virtually all of the light entering the top plate from the light source is subsequently confined by total internal reflection, reducing stray light from the system.

[0030] The vertical angular range of light rays propagating from the light source through the top plate can be restricted so that substantially all of the light coupled from the light source to the top plate is confined within the top plate by total internal reflection. It should be understood that the touch sensing device can be configured to increase the proportion of light coupled to the top plate that is confined within the top plate by total internal reflection, rather than increasing the total amount of light coupled to the top plate. In other words, the object of the present invention is to ensure that total internal reflection occurs on the first and second surfaces so that substantially all of the light coupled to the top plate is confined within the top plate. This is in contrast to prior art systems that prioritize maximizing the amount of light coupled to the plate or waveguide over the proportion of light that is confined within the waveguide after coupling to the waveguide.

[0031] One or more of the following can be configured to limit the vertical angular range of light propagating from the light source through the top plate: the angle of the refractive input surface with respect to the plane of the top plate, the mounting of the light source with respect to the refractive input surface, and the curvature of the refractive input surface. This allows the light to be confined within the top plate by total internal reflection while increasing the intensity of the evanescent field on the first surface.

[0032] By limiting and controlling the vertical angular range, the system can be optimized to increase the intensity of the evanescent field at the first surface while confining the light within the top plate by total internal reflection. The mounting of the light source can define the distance of the light source's emission area from one or more refractive input surfaces and / or determine (at least partially) the angle at which light from the light source is incident on one or more refractive input surfaces.

[0033] The recess may be defined on the second surface of the top plate. The area around the recess on the second surface may be entirely contained within the second surface.

[0034] The touch sensing device may include a plurality of secondary light sources associated with the top plate, such that light from the secondary light sources propagates through the top plate by total internal reflection. The secondary light sources are arranged in secondary recesses that extend linearly within the second surface of the top plate, and light from the secondary light sources is coupled to the top plate via the walls of the secondary recesses. The secondary light sources may form a linear array within the linearly extending secondary recesses.

[0035] In another embodiment, the present invention provides a touch sensing device comprising a top plate associated with one or more light sources, and a base plate having one or more detectors associated for detecting light propagated within the base plate, wherein light from the one or more light sources propagates within the top plate by total internal reflection. The top plate and base plate are configured such that when an external object touches a first surface of the top plate, light is coupled from a second surface of the top plate through the first surface of the base plate to the base plate. The device is configured such that the horizontal angular range of light from each of the one or more light sources increases as it enters the top plate through the incident surface of the top plate. The light-emitting region of each light source is positioned at a predetermined distance from the incident surface so as to limit the vertical angular range of light rays propagating from the light source within the top plate.

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

[0037] In another embodiment, a touch sensing device is provided comprising a top plate associated with a plurality of light sources and a base plate having one or more detectors associated for detecting light propagated within the base plate, wherein light from the plurality of light sources propagates within the top plate by total internal reflection. The top plate and base plate are configured such that when an external object 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 base plate to the base plate. The plurality of light sources are arranged in linearly extending recesses within the second surface of the top plate, and light from the plurality of light sources is coupled to the top plate via the walls of the recesses. The plurality of light sources form a linear array within the linearly extending recesses.

[0038] By providing a recess that extends linearly along the second surface of the top plate (effectively forming a groove on the second surface), a light source can be mounted in a way that allows light to be easily injected directly into the body of the top plate. This enables uniform and efficient light injection into the top plate.

[0039] A linearly extending recess may be straight or curved. Similarly, a linear array of light sources may be straight or curved.

[0040] The wall of the recess may form an angle with respect to the plane of the top plate, so that the wall and the second surface of the top plate form an obtuse angle within the top plate.

[0041] The mounting of the light source to the refracting surface wall may be such that it refracts the light, thereby confining it within the top plate by total internal reflection and increasing the intensity of the evanescent field.

[0042] The walls of the recesses may be lenticular.

[0043] Each light source may be mounted at an angle to the plane of the top plate such that the light emitted from the light source is mainly directed obliquely to the first surface.

[0044] Each of the light sources may be mounted such that the light emitted from the light source is directed at an angle primarily toward the wall of the recess.

[0045] By changing the mounting angle of the light source relative to the wall of the recess in this way, the intensity of the evanescent field can be increased or adjusted, thereby maximizing or adjusting the responsiveness of the device to touch.

[0046] The top plate may further include a narrow section in which the distance between the first and second surfaces is substantially constant, but is smaller than the distance between the first and second surfaces in the recess.

[0047] In some embodiments, a top plate of nearly uniform thickness is provided except for the recesses, but other arrangements are possible and can increase the possibility of controlling total reflected light.

[0048] The top plate may further include a tapered section where the distance between the first and second surfaces of the top plate is narrowed, and the tapered section is located between the recess and the narrow section.

[0049] The tapered portion may be linearly tapered. The tapered portion may be nonlinearly tapered.

[0050] The first surface region can be masked to prevent total internal reflection of light from multiple light sources within the groove.

[0051] By applying masking to a portion of the first surface located above the recess and extending beyond the recess, the incident angle range of light reflected from multiple light sources onto the first surface can be limited.

[0052] Masking may be provided by a light-absorbing layer on or provided on the first surface.

[0053] The recessed area between the light source and the first surface may be masked.

[0054] Masking may be provided by a light-absorbing layer on or on the surface of a recess.

[0055] Masking may be performed by a light-absorbing element attached to the light source.

[0056] By masking the recessed area, an opening can be defined for radiating light from the light source onto the top plate.

[0057] The top plate may have a linear projection on the second surface that extends away from the first surface, the linear extension of the linear projection being substantially parallel to the linear extension of the groove. The linear projection may have a rectangular or corrugated cross-section perpendicular to its linear extension.

[0058] In some embodiments, an air gap may exist between the top plate and the bottom plate. In other embodiments, a light-transmitting material layer may exist between the top plate and the bottom plate.

[0059] Multiple light sources may be spaced apart to form a substantially uniform light distribution within the body of the top plate. Each of the multiple light sources may be a light-emitting diode. Each light-emitting diode may emit near-infrared light.

[0060] In another embodiment, a touch sensing device is provided comprising a top plate associated with one or more light sources and a base plate having one or more detectors associated for detecting light propagated within the base plate, wherein light from multiple light sources propagates within the top plate by total internal reflection. The top plate and base plate are configured such that when an external object 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 base plate to the base plate. One or more regions of the first surface, the second surface, or both are provided with a layer that suppresses internal reflection of the surface in that region, thereby achieving optical separation between a part of the top plate and another part of the top plate.

[0061] This layer may also be an absorption layer.

[0062] The top plate is formed by molding, and the layers are formed by two-shot molding or in-mold labeling.

[0063] The layer can isolate at least one active region from other regions of the first surface, and each active region is isolated from other optical activity within the top plate. The active region may provide a single touch-sensitive device function.

[0064] The functionality of a touch-sensitive device consists of one of the following: a dial, slider, button, toggle, or touchscreen.

[0065] Each of the multiple light sources is positioned in a recess within the top plate, which is dedicated to that light source. The recess has one or more refractive input surfaces, and the light from the light source is coupled to the body of the top plate via one or more refractive input surfaces.

[0066] The wall of the refractive input surface may form an angle with respect to the plane of the top plate, so that the refractive input surface and the second surface of the top plate form an obtuse angle within the top plate.

[0067] The wall of the refractive input surface may be made into a lens.

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

[0069] Each light source may be mounted such that the light emitted from the light source is primarily directed obliquely to at least one refractive input surface.

[0070] Multiple light sources may be arranged around the perimeter of the active area. The perimeter of the active area may be rectangular. The perimeter of the active area may be elliptical.

[0071] The first surface of the top plate within the active area may not be flat.

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

[0073] Two of the multiple active regions may have different touch-sensing device functions. Two of the multiple active regions may have different optical properties. Two of the multiple active regions may have light sources with different properties. Two of the multiple active regions may be associated with regions of the base plate having different optical properties.

[0074] The touch sensing device may further include an absorbent layer on part or all of the outer periphery of the top plate.

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

[0076] In some embodiments, the light source emits near-infrared light, and the absorption layer can absorb near-infrared light. An additional layer may be provided in one or more regions of the first surface. This additional layer can absorb the visible spectrum. The additional layer may at least partially cover the absorption layer.

[0077] In another embodiment, a method for manufacturing a light-transmitting sheet is provided. This method comprises the steps of forming a light-transmitting sheet as a laminate and forming one or more light-absorbing layer regions on a first surface, a second surface, or both of the light-transmitting sheet, wherein the light-transmitting sheet is configured to exhibit total internal reflection on the first and second surfaces, and the one or more light-absorbing layer regions are formed during the forming step.

[0078] The light-absorbing layer region may be formed by in-mold labeling.

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

[0080] In another embodiment, a method for manufacturing an optical element for a touchscreen device is provided. This method comprises forming a light-transmitting sheet by the method of any of the above paragraphs, and laminating the light-transmitting sheet with an intermediate optical layer and a further light-transmitting sheet, wherein the intermediate optical layer has a lower refractive index than the light-transmitting sheet.

[0081] The intermediate optical layer can provide optical bonding between light-transmitting sheets. The intermediate optical layer may contain fluorinated ethylene propylene.

[0082] Optical elements can be formed by two-shot molding.

[0083] In another embodiment, a method for manufacturing a touchscreen device is provided. This method includes the steps of: manufacturing a light-transmitting sheet as one of the above paragraphs as a top plate; mounting the top plate in a touchscreen device with a plurality of light sources attached in association with it, so that light from the plurality of light sources propagates through total internal reflection within the top plate; mounting a base plate to the top plate so that when an external object 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 base plate to the base plate; and mounting one or more detectors associated with the base plate to detect light propagated within the base plate.

[0084] The top plate and base plate can also be mounted with an air gap between them. In such embodiments, the air gap may be provided by a foam mask separator.

[0085] A light-transmitting sheet can be manufactured by forming a light-transmitting sheet by any of the methods described in the paragraphs above, and laminating the light-transmitting sheet with an intermediate optical layer and a further light-transmitting sheet, wherein the intermediate optical layer has a lower refractive index than the light-transmitting sheet, and the base plate is the further light-transmitting sheet.

[0086] The base plate can be mounted on a display configured to emit light from a touchscreen device through a top plate.

[0087] The light-absorbing layer can be adapted to absorb light emitted from a light source and mask the light source. By masking the light source, the propagation of light from the light source through the top plate is substantially restricted, and only light directed to undergo total internal reflection at the surface of the top plate can propagate.

[0088] The light source emits near-infrared light, and the light-absorbing layer region may absorb near-infrared light.

[0089] The base plate may weakly absorb light emitted from multiple light sources. The base plate may be chemically doped with a weakly absorbing material.

[0090] The top plate may extend beyond the base plate. One or more light sources may be mounted in the area of ​​the top plate that extends beyond the base plate.

[0091] The top plate may be manufactured to taper from a thicker area where one or more light sources are mounted to a thinner area where the top plate rests on the base plate.

[0092] One or more light sources may be mounted in one or more recesses on the second surface of the top plate, and arranged so as to propagate light into the top plate through the walls of the recesses in which the light sources are located.

[0093] The recess may be a linearly extending recess, and multiple light sources may be mounted within the recess in a linear array.

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

[0095] One or more recesses can be formed for each of one or more light sources. Each recess has one or more refractive input surfaces, and light from the light source is coupled to the body of the top plate via one or more refractive input surfaces.

[0096] The base plate may be mounted in such a way that it prevents light emitted from the base plate that is not received by one or more detectors from passing through the top plate.

[0097] In another embodiment, a packaged light-emitting diode is provided, comprising a light-emitting diode die and a cylindrical lens directly mounted on the light-emitting surface of the light-emitting diode die, wherein the light emitted through the cylindrical lens has a narrow angular distribution along a first axis and a broad angular distribution along a second axis perpendicular to the first axis.

[0098] The cylindrical lens may be formed as a substantially flattened ellipsoidal lens with its top truncated, having a body with two first truncations and one second truncation. The two first truncations may be perpendicular to the axis of the flattened ellipsoid, equidistant from the longest semi-axis of the flattened ellipsoid, parallel to the two axes of the flattened ellipsoid, and parallel to each other. The second truncation may be parallel to the other axis of the flattened ellipsoid and perpendicular to the two first truncations. The light-emitting diode die may be close to the second truncation.

[0099] The cylindrical lens may also be a flattened ellipsoid.

[0100] The cylindrical lens may be formed as an aspherical lens in a deformed ellipsoid, which has two first truncations and one second truncation. The two first truncations may be perpendicular to the axis of the deformed ellipsoid, equidistant from the longest semi-axis of the deformed ellipsoid, parallel to the two axes of the flattened ellipsoid, and parallel to each other. The second truncation may be parallel to the other axis of the flattened ellipsoid and perpendicular to the two first truncations.

[0101] The light-emitting diode die may be close to the second truncation. The ellipsoid may be modified such that its curvature is greater in the direction perpendicular to the light-emitting surface of the light-emitting diode die and smaller in the direction parallel to the light-emitting surface of the light-emitting diode die.

[0102] The lengths of the two first truncated portions perpendicular to the light-emitting surface of the light-emitting diode die may be longer than half the length of the lens body perpendicular to the light-emitting surface of the light-emitting diode die.

[0103] In another embodiment, a touch sensing device is provided, comprising a top plate associated with one or more light sources, and a base plate having one or more detectors associated for detecting light propagated within the base plate, wherein light from the one or more light sources propagates within the top plate by total internal reflection. The top plate and base plate are configured such that when an external object touches a first surface of the top plate, light is coupled from a second surface of the top plate through the first surface of the base plate to the base plate. Each of the one or more light sources is located in a recess for the light source within the top plate, the recess having a refractive input surface, and light from the light source is coupled to the body of the top plate via the refractive input surface. Each of the one or more light sources is a light-emitting diode packaged as described in the previous paragraph.

[0104] The combination of the light source lens and the shape of the refractive input surface may enable nearly uniform diffusion of light within the plane of the top plate, and one or more light sources may be mounted on the refractive input surface.

[0105] The wall of the refractive input surface may form an angle with respect to the plane of the top plate such that the refractive input surface and the second surface of the top plate form an obtuse angle within the top plate.

[0106] Each light source may be mounted at an angle to the plane of the top plate such that the light emitted from the light source is mainly directed obliquely to the first surface.

[0107] Each light source may be mounted such that the light emitted from the light source is directed at an oblique angle to the refractive input surface.

[0108] The approaches, functions, and embodiments described above can be used individually or in combination. Features of one embodiment can be applied individually or in appropriate combinations to features of another embodiment. [Brief explanation of the drawing]

[0109] To facilitate understanding of the present invention, preferred non-limiting embodiments of the invention are described below with reference to the accompanying drawings, through mere illustration. [Figure 1] Figure 1 is a schematic cross-sectional view of the touchscreen layout. [Figure 2] Figure 2 shows the layout of the touchscreen integrated into the vehicle's cabin. [Figure 3] Figure 3 is a cross-sectional view of a portion of the optical guide, incorporating a light source located in the recess on the underside of the optical guide. [Figure 4] Figure 4 is a cross-sectional view of a portion of another optical guide, incorporating a light source located in the recess on the underside of the optical guide. [Figure 5] Figure 5 is a perspective view showing a portion of the optical guide, including the trench injection optical shape and the tapered section. [Figure 6] Figure 6 is a perspective view showing a portion of another optical guide, which incorporates a trench injection optical shape and has a certain thickness. [Figure 7]Figure 7 is a perspective view showing a portion of the optical guide incorporating the pocket injection optics. [Figure 8a] Figure 8a shows the angular range of light rays that exceed the critical angle at the boundary between acrylic and air. [Figure 8b] Figure 8b shows the angular range of light rays that exceed the critical angle at the boundary between acrylic and FEP. [Figure 9] Figure 9 is a cross-sectional view of a portion of the optical guide, showing the light source incorporated in the recess located on the underside of the optical guide. [Figure 10] Figure 10 is a cross-sectional view showing a portion of another optical guide incorporating a light source located in the recess on the underside of the optical guide. An absorption mask is provided on the upper surface of the optical guide. [Figure 11] Figure 11 is a perspective side view showing a portion of an optical guide, incorporating a recess for housing a light source during use. The recess is provided with a lens-shaped front wall. [Figure 12a] Figure 12a is a graph showing the light loss from the optical guide, as well as the light coupled to the optical guide and the power density within the optical guide, for each inclination angle of the front wall of the recess, when light is injected into the optical guide from a light source located in the recess below the optical guide. [Figure 12b] Figure 12b is a cross-sectional view showing a portion of the optical guide, incorporating a light source located in the recess on the underside of the optical guide. The front wall of the recess is not inclined. [Figure 12c] Figure 12c is a cross-sectional view showing a portion of the optical guide with a light source incorporated in the recess located on the underside of the optical guide. The inclination angle of the front wall of the recess is 50°. [Figure 13a] Figure 13a is a graph showing the light loss from the optical guide, as well as the light coupled to the optical guide and the power density within the optical guide, for each inclination angle of the front wall of the recess, when light is injected into the optical guide from a light source located in the recess below the optical guide. [Figure 13b] Figure 13b is a cross-sectional view showing a portion of the optical guide with a light source incorporated into the recess located in the lower part of the optical guide. The front wall of the light source recess is not sloped, and the light source itself is also not sloped. [Figure 13c]Figure 13c is a cross-sectional view showing a portion of the optical guide with a light source incorporated into the recess located in the lower part of the optical guide. The inclination angle of the front wall of the light source recess is 30°, and the central axis of the light source is approximately perpendicular to the front wall of the recess. [Figure 14] Figure 14 is a perspective side view showing a portion of an optical guide, incorporating a recess for housing a light source when in use. The optical guide includes an extruded section or groove adjacent to the front wall of the recess. [Figure 15] Figure 15 is a perspective side view showing part of another optical guide, which incorporates a recess for housing a light source when in use. This optical guide has a nonlinear tapered section. [Figure 16] Figure 16 shows the layout of the touchscreen, which incorporates a slider, a D-pad, and a raised rectangular screen. [Figure 17a] Figure 17a is a schematic perspective view showing a portion of a trench injection optical system having a linearly extending front wall. [Figure 17b] Figure 17b is a schematic perspective view showing a portion of a trench injection optical system with a curved, linearly extending front wall. [Figure 18a] Figure 18a is a schematic perspective view of a pocket injection optical system in which the height and slope of the front wall of the recess vary with respect to its length. [Figure 18b] Figure 18b is a schematic perspective view of a pocket injection optical system incorporated into an optical guide having a tapered section. [Figure 19] Figure 19 is a schematic perspective view of an optical guide incorporating multiple pocket injection optics and including an absorption mask layer on the top surface. [Figure 20] Figure 20 is a top view of an optical guide incorporating a pocket injection optical system. [Figure 21a] Figure 21a is a side view showing a portion of the optical guide, incorporating a light source located in the recess on the underside of the optical guide. [Figure 21b] Figure 21b shows the intensity distribution of the output from the light source in the configuration shown in Figure 21a. [Figure 21c] Figure 21c shows the intensity distribution of light from the light source within the optical guide in Figure 21a. [Figure 22a] Figure 22a shows the horizontal and vertical intensity distributions of light from a wide-angle surface-mount LED device. [Figure 22b] Figure 22b shows the horizontal and vertical intensity distributions of light from a narrow-angle surface-mount LED device. [Figure 23a] Figure 23a is a perspective view of an LED device with a circular lens incorporated into it. [Figure 23b] Figure 23b shows the horizontal and vertical intensity distributions of light from the apparatus shown in Figure 23a. [Figure 24a] Figure 24a is a perspective view of a hyperelliptical LED package with a cylindrical lens incorporated into it. [Figure 24b] Figure 24b shows the horizontal and vertical intensity distributions of light from the apparatus shown in Figure 24a. [Figure 24c] Figure 24c is a plan view of the LED package shown in Figure 24a. [Figure 25a] Figure 25a is a side view showing a portion of the light guide into which the LED package shown in Figure 24a is incorporated. [Figure 25b] Figure 25b is a perspective view showing a portion of the light guide incorporating the LED package shown in Figure 24a. [Figure 25c] Figure 25c shows the intensity distribution of the output from the LED package in Figure 24a, displayed separately. [Figure 25d] Figure 25d shows the intensity distribution of light from the light source within the optical guide in Figure 25b. [Figure 26] Figure 26 is a graph showing the relationship between the uniformity of the light intensity distribution within the optical guide and the distance in the Z direction from the pocket injection optical system. [Figure 27] Figure 27 is a graph showing how the light output from the LED and the horizontal and vertical beam half-angles of the LED change with the size of the LED chip. [Figure 28] Figure 28 is a perspective view of an optical guide with a curved profile and incorporating 16 pocket injection optics. [Figure 29a]Figure 29a is another perspective view of the optical guide in Figure 28, showing the distribution of light within the optical guide. [Figure 29b] Figure 29b is a perspective view of a curved optical guide incorporating 12 pocket injection optics, showing the distribution of light within the optical guide. [Figure 29c] Figure 29c is a perspective view of a curved optical guide incorporating eight pocket injection optics, showing the distribution of light within the optical guide. [Figure 29d] Figure 29d is a graph showing the uniformity of optical power density at the side walls of each optical guide in Figures 29a-c, at different angular positions around the central axis C of the optical guide. [Figure 30] Figure 30 is a perspective view of an optical guide with a rectangular profile and incorporating 32 pocket injection optics. [Figure 31a] Figure 31a is another perspective view of the optical guide in Figure 30, showing the distribution of light within the optical guide. [Figure 31b] Figure 31b is a perspective view of a rectangular optical guide incorporating 26 pocket injection optics, showing the distribution of light within the optical guide. [Figure 31c] Figure 31c is a perspective view of a rectangular optical guide incorporating 20 pocket injection optics, showing the distribution of light within the optical guide. [Figure 31d] Figure 31d is a graph showing the uniformity of optical power density along the x-axis for each optical guide in Figures 31a-c. [Figure 32] Figure 32 is a perspective view of a curved optical guide incorporating active and inactive regions. [Figure 33] Figure 33 is a perspective view of a planar light guide incorporating multiple active regions separated by inactive regions defined by an absorption mask layer. [Figure 34a] Figure 34a is a cross-sectional side view of a curved optical guide incorporating injection optics positioned at both ends and absorbers positioned at the end faces. [Figure 34b]Figure 34b is a cross-sectional side view of a curved optical guide incorporating injection optics positioned at both ends and absorbers positioned along the end walls. [Figure 35a] Figure 35a is a cross-sectional side view of a curved optical guide incorporating injection optics positioned at both ends, showing stray light reflected from one of the injection optics. [Figure 35b] Figure 35b is a cross-sectional side view of a curved optical guide incorporating injection optics positioned at both ends and an absorber extending across one of the injection optics. [Figure 36] Figure 36 is a cross-sectional side view of a portion of a touch-sensing device formed from a composite material. [Figure 37] Figure 37 is a cross-sectional side view showing a portion of another touch-sensing device formed from a composite material. [Figure 38] Figure 38 is a cross-sectional side view showing a portion of another touch-sensing device formed by a laminate. [Figure 39] Figure 39 is a cross-sectional side view showing a portion of another touch-sensing device formed by a laminate. [Figure 40] Figure 40 shows a curved optical guide, and the radius of curvature and thickness of the optical guide are shown, which are used to calculate the curvature ratio of the dial corners. [Figure 41a] Figure 41a shows a pocket injection optical system that provides a narrow light distribution. [Figure 41b] Figure 41b shows a pocket injection optical system that provides a broad light distribution within a curved optical guide. [Figure 42a] Figure 42a shows another example of an HE-LED package incorporating an aspherical lens. [Figure 42b] Figure 42b shows the horizontal and vertical intensity distributions of light from the device shown in Figure 42a. [Figure 42c] Figure 42c is a plan view of the HE-LED package shown in Figure 42a. [Figure 43] Figure 43 shows an intermediate layer formed from multiple sublayers, which is used as an intermediate layer in a laminate. [Modes for carrying out the invention]

[0110] Optical touch-sensitive light guides, which use flat light guides and are mainly marketed as whiteboard upgrades, are well known. However, the market is moving in a new direction, and there is a need to introduce thin, continuous 3D curved top layers that provide a single, free-flowing shape (a shape without mechanical elements that penetrate the surface) to achieve a more sophisticated and aesthetically pleasing style. Safety is also a crucial factor, and features such as geometric indentations and grooves should be added to the top surface of the top layer so that (a) finger positioning and guidance are aided, and (b) users can identify relevant parts on the touchscreen with touch alone, without having to look where their fingers are placed (i.e., "keep your eyes on the road").

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

[0112] The apparatus of the present invention can, for example, utilize the touchscreen technology developed by the applicant and described in WO2015 / 155508. In the approach taught in WO2015 / 155508, attenuated total internal reflection is used in combination with a lossy baseplate 18. The transmission loss between the incident light on the baseplate element 18 and one or more detectors 20 associated with the baseplate 18 can be used by the processing means to determine the touch position. Such a lossy baseplate 18 may be one that weakly absorbs light emitted from an associated light source, and may be chemically doped with a weakly absorbing material for this purpose.

[0113] Referring to Figure 1 illustrating the approach taught in WO2015 / 155508, the HDI8 comprises a three-layer optical laminate above one or more displays (not shown in Figure 1). Light is coupled to the top plate or upper layer 10 of the laminate and confined within this upper optical guide 10 by total internal reflection. When the first surface or upper surface 23 of the upper layer 10 is touched, a small percentage of the light confined in the upper layer 10 is emitted from the second surface or lower surface 25 of the upper layer 10 and transmitted through the intermediate layer 14 (air or a material with a lower refractive index) toward the first surface or upper surface 26 of the lower laminate plate 18 (i.e., the base plate 18), where the light is detected and the position of the finger press on the upper surface 23 is determined. The lower laminate plate 18 is doped so that the light is dispersed within the lower laminate plate 18 so that the position of the finger press can be calculated from the light detected by the photodetector 20. Multiple photodetectors 20 may be arranged around the lower stacked plate 18, and these can be arranged to most effectively detect the finger press position in accordance with the shape of the HDI 8.

[0114] By using a novel approach to light injection, a uniform light profile within the upper layer 10 optical guide was found to be achievable, enabling the development of particularly effective HDI8. A novel method and apparatus for injecting light into the upper layer 10 optical guide and shaping the distribution of the injected light to improve touch sensitivity response is described. A manufacturing method for the laminated structure suitable for mass production is also described. The novel 3D optical guide geometry described requires a novel method for coupling or "injecting" light into the top plate 10, which minimizes light loss in shape features such as curved portions of the top plate 10, efficiently utilizing the available light and efficiently distributing it where it is most needed. Furthermore, the novel optical guide can be easily manufactured (using injection molding technology, for example) and its structure can be simplified by minimizing the form factor using surface mount device (SMD) components.

[0115] The inefficiencies associated with edge injection of light within the optical guide are resolved by injecting light into the top plate 10, which is closest to the shape where the light is most needed. As a result, the light does not travel unnecessarily long distances before reaching the active area of ​​the touchscreen where a touch on the top surface 23 of the top plate 10 can be detected. Furthermore, the injected light does not disperse before it is "used," i.e., within the active touch detection area of ​​the touchscreen 8. A crucial aspect of efficiency is ensuring that all light traveling within the optical guide is "useful" light (i.e., light traveling in the appropriate trajectory for the touch detection process to work as intended). Thus, useless light may not contribute to the signal, but it may contribute to noise. Therefore, to achieve the best signal-to-noise ratio, it is more important to prevent the propagation of stray light than simply maximizing the amount of light entering the top plate 10.

[0116] Referring to Figure 3, a means for injecting light from the light source 12 into the optical guide 10 is shown. The arrangement in Figure 3 can be incorporated, for example, as the top plate 10 of a touch detection system 8 as shown in Figure 1.

[0117] In this example, the optical guide 10 has a constant thickness t. L The optical guide 10 is defined by a curved plate, the thickness of which is defined as the distance between the upper surface 23 and the lower surface 25 of the optical guide 10. The optical guide 10 may be planar in shape or may have various other three-dimensional (3D) shapes. Unlike conventional systems in which light is coupled to the optical guide 10 via its edges, in the example of Figure 3, the light is coupled to the optical guide 10 at a position inside the edges of the optical guide 10 (however, the coupling position is not limited to this position within the optical guide 10). In this way, the light is coupled to the optical guide 10 at a position close to the starting point of the desired location (i.e., close to the active area of ​​the optical guide 10 where the light is used for touch detection).

[0118] As shown in Figure 3, the optical guide 10 includes a recess or cavity 30 for housing a light source 12 (an LED in this example). The recess 30 is formed on the second surface (bottom surface) 25, which is the bottom surface of the optical guide 10, and is made of a thickness (t) of the optical guide 10 so as not to penetrate the top surface 23 of the optical guide 10. L It extends in part in the direction. In this way, the recess 30 extends from the lower surface 25 of the optical guide 10 toward the upper surface 23 of the optical guide 10, terminates below the upper surface 23, and the top surface 32 of the recess 30 is positioned between the upper surface 23 and the lower surface 25 of the optical guide 10. The portion of the optical guide between the top surface 32 and the upper surface 23 defines the roof portion 34 of the recess 30. In other words, the portion of the optical guide 10 above the recess 30 defines the roof portion 34 of the recess 30 (see Figure 4 in particular).

[0119] The recess 30 comprises a front surface 36 and a rear surface 38 as shown in Figure 3, as well as a side surface (not shown in Figure 3). The front surface 36 and the rear surface 38 are inclined toward each other as they move from the bottom surface 25 toward the top surface 23. In this way, the width of the recess 30 is tapered, and the width between the front surface (or front wall) 36 and the rear surface (or rear wall) 38 in the recess 30 decreases from the bottom surface 25 of the optical guide 10 toward the top surface 23 of the optical guide 10. Note that the rear surface 38 needs to be inclined only to create a draft angle for injection molding. Here, considering the optical coupling end of the recess 30 in particular, the front wall 36 forms an angle with respect to the plane of the optical guide or top plate 10 in the region in which the light source recess 30 is incorporated, and as a result, the front wall 36 and the second surface or bottom surface 25 of the top plate 10 form an obtuse angle within the top plate 10, forming a refractive input surface. In this example, the side surface is inclined inward from the bottom surface 25 toward the top surface 23, but this may differ in other examples. For example, the side surface could extend vertically between the top surface 23 and the bottom surface 25, but it is usually sloped to allow injection molding. In other examples, it should be understood that the shape of the recess 30 can vary.

[0120] As shown in Figure 3, when the light source 12 is positioned within the recess 30, the radiation area 40 of the light source 12, from which light is emitted, is directed toward the front surface 36 of the recess 30. In this way, light is emitted from the light source 12 to the optical guide 10 via the front surface 36 of the recess 30, which acts as the optical coupling surface or wall of the recess 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 the light source recess 30 to block light emitted from the light source 12 from exiting the light source recess 30 via the top surface 32 or rear surface 38. In this way, the absorbers 42 prevent undesirable stray light that does not reach the active touch detection area of ​​the optical guide 10 from being emitted upward, backward, or to the side of the light source 12. This eliminates stray light that could interfere with the touch detection system. In this example, the absorbers 42 are further provided below the bottom surface 25 of the optical guide 10, adjacent to the light source recess 30, to prevent reflection of light from the light source 12 in this area. Thus, light that does not meet the critical angle criterion for total internal reflection may have its propagation within the optical guide 10 blocked.

[0121] In the example shown in Figure 3, the optical guide 10 comprises a single recess 30 configured to accommodate one light source 12. However, it should be understood that in other examples, the optical guide 10 may include multiple recesses 30, each recess 30 configured to accommodate one or more light sources 12. Furthermore, in some examples, the optical guide 10 may comprise a single recess 30 configured to accommodate multiple light sources 12.

[0122] Therefore, as described above, at least one recess 30 is provided by cutting into the underside of the optical guide 10, and the recess 30 is large enough to accommodate a single light source 12 or multiple light sources 12. The size and dimensions of the light source 12 determine the size and dimensions of the recess 30 required to accommodate the light source 12 while having clearance tolerances that are suitable for a good mechanical design. For mass-produced optical components, injection molding is typically chosen as the manufacturing method. In this case, the minimum roof thickness t that can be reliably molded onto the light source 12 (in this case, in the form of an LED) is specified. RThis is necessary. Otherwise, a "recess" that is functionally and aesthetically unacceptable may occur on the upper surface 23 of the light guide 10 above the LED. R h is defined as the thickness of the roof portion 34 of the recess 30, and as the distance between the top surface 32 of the recess 30 and the upper surface 23 of the light guide. In the embodiment shown in Figure 3, the height h of the LED L A relatively thick light guide section is used, and the roof portion 34 of the recess 30 is thick enough to accommodate the LED 12 without any recess appearing on the upper surface 23 of the light guide 10 above the LED 12. R It holds.

[0123] Figure 4 shows another embodiment of a means for injecting light from a light source 12 into an optical guide 10 for use in a touch-sensitive optical system. In this example, the optical guide 10 includes a relatively thick first section 46 and a relatively thin second section 48 (i.e., a narrower section). 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 optical guide 10 is greater in the first section 46 than in the second section 48. The light source recess 30 is provided in the relatively thick first section 46 of the optical guide 10. The tapered portion 50 of the optical guide 10 connects the first section 46 (i.e., the thicker recessed section) and the second section 48 (i.e., the thinner optical guide section), with the distance between the first surface 23 and the second surface 25 decreasing away from the front wall 36 of the recess 30.

[0124] Similar to the light source recess 30 in Figure 3, the light source recess 30 in the arrangement shown in Figure 4 is defined on the lower surface 25 of the optical guide 10 and partially extends in the thickness direction of a portion of the optical guide 10. The recess 30 terminates at the top surface 32 of the recess 30, which is located between the upper surface 23 and the lower surface 25 of the optical guide 10, and the portion of the optical guide 10 between the top surface 32 and the upper surface 23 defines the roof portion 34 of the recess 30. The recess 30 includes the front surface 36 and rear surface 38 shown in Figure 4, as well as the sides (not shown in Figure 4). The front surface 36 and rear surface 38 are inclined toward each other as they move from the lower surface 25 toward the upper surface 23. In this way, the width of the recess 30 in Figure 4 is slightly tapered, and the width of the recess 30 between the front surface 36 and the rear surface 38 decreases from the lower surface 25 of the optical guide 10 toward the upper surface 23 of the optical guide 10, although this tapered shape in the arrangement in Figure 4 is less pronounced than that shown in Figure 3. This side slopes inward from the bottom surface 25 to the top surface 23, but this may differ in other examples. Please understand that the shape of the recess 30 may vary in other examples.

[0125] Similar to the arrangement in Figure 3, the radiation area 40 of the light source 12 positioned within the recess 30 in Figure 4 is directed toward the front surface 36 of the recess 30, which functions as an optical coupling surface. The optical coupling surface 36 defines the refracting input surface of the optical guide 10, into which the light from the light source 12 is refracted. For the same reasons already explained in relation to Figure 3, the absorber 42 is positioned adjacent to the light source recess 30, above the top surface 32 and below the bottom surface 25 of the optical guide 10.

[0126] Next, referring to Figure 5, a light source recess 30 similar to the light source recess 30 shown in Figure 4, but with dimensions to accommodate multiple light sources 12 (only one is labeled in Figure 5 for clarity), is incorporated into the curved optical guide 10. The optical guide 10 in Figure 5 is curved two-dimensionally, particularly in the y and z dimensions, as defined in Figure 5. The optical guide 10 in Figure 5 is extruded symmetrically about the x-axis, as also defined in Figure 5.

[0127] Light emitted from the light source 12 passes through the refracting input surface 36 and the tapered portion 50 of the optical guide 10, where it is confined within the optical guide 10 by total internal reflection. The light source array 12 is spaced apart along the length of the linearly extending recess 30, forming a linear array within the recess 30 and creating a substantially uniform light distribution within the optical guide or the body of the top plate 10.

[0128] The optical coupling surface 36 into which light is injected into the optical guide 10, and the tapered optical guide section 50 are configured taking into consideration the spatial and angular characteristics of the light source 12. especially, a) The system is configured to maximize the light injection efficiency from one or more light sources 12 to the optical guide 10. This can be achieved, for example, by optically polishing the optical coupling surface 36. b) By ensuring that rays do not fall outside the critical angle range at the upper surface 23 and / or lower surface 25 of the optical guide 10, optical losses are canceled or minimized, particularly in the vertical plane (i.e., the angle of incidence of rays hitting the upper surface 23 / lower surface 25 with respect to the surface normal of the upper surface 23 / lower surface 25 does not fall below the relevant critical angle defined with respect to the surface normal of the upper surface 23 / lower surface 25). c) By controlling the average angle of incidence of light rays (relative to the surface normal) on the upper surface 23 of the optical guide, the touch sensitivity of the system incorporating the optical guide 10 is maximized, as described above. Specifically, the injection optical system is configured such that the average angle of incidence of light rays emitted from the light source 12 and striking the upper and lower surfaces 23 and 25 of the optical guide 10 is close to the critical angle. The angle of incidence α of the light rays striking the upper surface 23 / lower surface 25 is defined with respect to the surface normal of the upper surface 23 / lower surface 25, as is common in this field and shown in Figure 1 for completeness and clarity. It has been shown that as the angle of incidence of light rays totally internally reflected at the boundary approaches the critical angle, the depth of the evanescent field (i.e., the penetration of the evanescent field) increases. Therefore, configuring the injection optical system so that light rays totally internally reflected within the optical guide 10 propagate at an angle as close as possible to the critical angle increases the depth of the evanescent field, and as a result, the touch sensitivity of the system utilizing frustrated total internal reflection in the touch detection process is improved. In particular, if the optical guide 10 is curved, it will be understood that the angle between the incident light ray from the light source 12 and the upper surface 23 / lower surface 25 of the optical guide 10 may change as the light passes through the optical guide 10 by total internal reflection. For example, if the angle α at which the light strikes the upper surface 23 / lower surface 25 of the optical guide 10 decreases and falls below the critical angle, and below the angular threshold for total internal reflection, light will be lost from the optical guide 10. By selecting the vertical angular range of the incident light coupled to the optical guide 10 with this consideration in mind, a balance can be struck between the benefits of increasing the depth of the evanescent field and the light loss that occurs when the incident angle α of the light ray falls below the critical angle. With these points in mind, it will be understood that when mounting the light source 12 against the wall of the refractive surface 36, it may be positioned to refract the light and increase the intensity of the evanescent field, while simultaneously confining the light within the top plate 10 by total internal reflection. d) By diffusing the light rays, particularly in the horizontal plane, the uniformity of the optical power density on the upper surface 23 of the optical guide 10 is optimized, thereby improving the uniformity of the touch response across the entire touch-sensing area of ​​the system. e) The optical recess shape is large enough to accommodate one or more light-emitting packages 12 depending on the application, while being small enough to minimize the distance between the back surface of the optical recess 30 (i.e., the back surface 38 of the light source recess 30) and the starting point of the active area of ​​the touch surface. f) Improve the ease of manufacturing the optical recess shape.

[0129] In Figures 5 and 6, the recess 30 defines a linearly extending recess within the top plate 10 for accommodating multiple light sources 12 and is referred to as a “trench injection optical system” (TIO) 52. In other embodiments, the recess 30 is sized and positioned to accommodate a single light source 12, as shown in Figure 7, and is referred to as a “pocket injection optical system” (PIO) 74. Other variations are possible. It should be noted that in the embodiments of Figures 5 and 6, the linearly extending recess extends linearly across the optical guide 10, but this may not be the case in other embodiments. For example, in other embodiments, the linearly extending recess may extend along a curved path. In some modifications, the recess 30 may extend across the top plate 10 along, for example, a conical or aspherical path, along a path defined by a spline, or along other paths consisting of one or more sections, which are not all listed here but will be apparent to those skilled in the art.

[0130] It should be understood that one or more trench injection optics 52 can be combined with one or more pocket injection optics 74 within the same top plate 10, and / or more generally, within the same touch-sensing device or system.

[0131] Typically, in the case of a flat optical waveguide 10 having a planar upper surface 23 and a lower surface 25 that extend parallel to each other, when light is coupled or "injected" into the optical waveguide 10, if the angle between the reflected ray and the surface normal is greater than the critical angle determined by the refractive index of the material of the optical waveguide 10, the light is confined within the optical waveguide 10. FIGS. 8a and 8b show the path of a ray of light traveling through an optical waveguide 10 formed of an acrylic material and hitting the lower surface 25 of the optical waveguide 10 at the critical angle. In FIG. 8a, the lower surface 25 defines the interface between the acrylic material of the optical waveguide 10 and an air gap that defines an intermediate layer 14 between the optical waveguide 10 and the bottom plate 18, and the critical angle at this interface is approximately 42°. In FIG. 8b, a layer of a fluorinated polymer, fluorinated ethylene propylene (FEP) material, is provided between the top plate 10 and the bottom plate 18 to define the intermediate layer 14, and the critical angle at the interface is approximately 64°.

[0132] However, in the case of an optical waveguide 10 having a more complex surface profile, such as a 3D depression or dome, for example, additional requirements need to be met in order to minimize the optical losses that occur during the propagation of light through the optical waveguide 10. When using a light source 12 having a relatively small divergence angle, a general rule for minimizing the optical loss from the optical waveguide 10 is to make the ratio of the bending radius to the thickness of the optical waveguide exceed 5 to 1 in the curvature of the optical waveguide. That is, referring to FIG. 40, the radius of curvature R c of the optical waveguide 10 in a particular region, P and the thickness t d of the optical waveguide 10 in that particular region, d should have a ratio that exceeds 5 / 1. This ratio is called the dial corner curvature ratio K c and is defined as K p = R / t > 5 / 1.

[0133] While the use of this rule is generally effective when using a light source 12 that emits light with a relatively small divergence angle, if the divergence angle of the light source 12 is large, especially if the optical guide 10 bends successively in opposite directions (for example, if the shape profile of the optical guide 10 is deflected in an "S" shape), at least some of the rays from the light source 12 will fall below the relevant critical angle, increasing the likelihood of light loss from the optical guide 10.

[0134] In devices utilizing optical touch detection, the loss of light from the system, particularly from the optical guide 10, is highly undesirable. Leaked light, i.e., light lost from the optical guide 10, can be reflected back into the system by the user, potentially causing the system to misdetect a touch. For example, if the user's hand is near the optical guide 10, even if the hand is not touching the upper surface 23 of the optical guide 10, leaked light can be reflected back into the system, potentially causing a misdetection of a touch. Furthermore, the light reflected back into the system can reduce the accuracy of the finger press position determined by the system, potentially degrading the overall press response. As will be discussed later, this problem can be addressed by limiting the angular range of the light rays coupled from the light source 12 to the optical guide 10. This ensures that almost all light rays propagating within the optical guide 10 remain at an angle higher than the critical angle throughout their propagation within the optical guide 10, preventing them from escaping the optical guide 10 by falling below the critical angle.

[0135] Returning to Figures 5 and 6, we will describe in more detail the simplified optical shape using the trench injection optical system 52.

[0136] The trench injection optical geometry is essentially a 2D design of a vertical plane (i.e., the yz plane) and is extruded along the x-axis.

[0137] The ideal shape of the 3D geometry for the trench injection optics 52 or pocket injection optics (details below) can be simplified by separating the vertical and horizontal profiles rather than determining them all at once. The following sections describe how to design and optimize the horizontal and vertical profiles independently and combine them to achieve the complete 3D geometry of the trench injection optics 52.

[0138] It is recognized that the optical performance in the vertical plane is not entirely independent of the shape in the horizontal plane (or vice versa), and that the optical performance of the trench injection optics 52 can be further improved by complete 3D optimization. However, considering the vertical and horizontal profiles separately simplifies the optimization process and results in better combined performance of the trench injection optics 52.

[0139] First, looking at the vertical profile of the trench injection optical system 52 in the yz plane, the main requirements for optimizing the design geometry of the trench injection optical system 52 in the vertical plane are as follows: i. Maximize the optical coupling efficiency to the optical guide 10. ii. Maximize the optical power density (or evanescent field) on the upper surface 23 of the optical guide 10. iii. Minimize light loss in the optical guide 10 (mainly due to loss from the upper surface 23 and lower surface 25 of the optical guide). It should be noted that light lost from the system through the roof portion 34 and the rear wall (or back wall) 38 of the recess 30 of the optical guide 10, or light hitting the printed circuit board (PCB) 54 below the light source 12, is not included in the following analysis. iv. Minimize the distance between the rear wall (or back wall) 38 of the trench injection optical system 52 and the active region of the optical guide 10 (i.e., the region of the optical guide 10 in which touch to the upper surface 23 of the optical guide 10 can be detected by the system).

[0140] By using several factors (mainly related to the numerical aperture of the optical system and the refractive index of the optical guide material), the range of ray angles propagating within the optical guide 10 can be controlled or limited, thereby minimizing optical loss.

[0141] The size of the light source 12 that emits light into the light guide 10 is an important factor, and many suitable light sources exist on the market for this application. LEDs 12 are considered suitable due to their small size, fast response, and wide wavelength range. However, it should be understood that the principle described herein is applicable to any suitable light source 12, and the present invention is not limited to the use of LEDs 12.

[0142] To ensure proper optical coupling efficiency of light to the optical guide 10, the size of the light source 12 is typically selected to be at least one-quarter the thickness of the optical guide. Depending on the application, a light source 12 with a wide-angle or narrow-angle light distribution may also be selected, requiring the concentration or spread of the light distribution accordingly. As mentioned above, the objective here is not simply to maximize the coupling of all light (including light at angles that do not contribute to the signal but may contribute to noise), but to maximize the coupling of useful light to the optical guide 10. Although this invention primarily relates to scenarios in which a narrow-angle light source 12 is used, the techniques described are equally applicable to a wide-angle light source 12.

[0143] Increasing the distance between the light-emitting area 40 of the LED 12 (i.e., the LED chip 40) and the refractive input surface 36 (when the aperture width is fixed - see the relevant explanation below) narrows the vertical angular range of the light rays coupled (or "injected") into the optical guide 10 via the refractive input surface 36. Referring to Figure 9, the distance between the LED chip 40 and the refractive input surface 36 is Z LEDThe angular range of light rays in the vertical or Z direction that are coupled to the optical guide 10 is shown by θ. It can be seen that reducing the vertical angular ray range θ reduces the optical coupling efficiency because light outside the vertical angular range is not coupled to the optical guide 10. On the other hand, the advantage of reducing the vertical angular range θ is that, in particular, in an optical guide 10 with vertical curvature that defines a tight bending radius, the likelihood of light being lost from the optical guide 10 as it passes through the optical guide 10 is reduced.

[0144] A further method for limiting the angular range of light rays coupled to the optical guide 10 is to use an aperture 56. The aperture 56 can be defined using an absorption mask 58 applied to the top surface 32 and along the base or legs 60 of the recess 30. The material of the absorption mask 58 is selected to absorb light in the wavelength range emitted by the associated light source 12 located within the recess 30. In embodiments of the present invention, the light source 12 located within the recess 30 emits light in the near-infrared wavelength range, and the absorption mask 58 can absorb light in the near-infrared wavelength range accordingly. In some examples, the absorption mask 58 may be black paint. As will be further described below, one approach that can be adopted is to mask only the light in the "operating" range for detection, and not mask other light. This allows other light to be used for other purposes (for example, the masking works only for infrared light, and visible light is transmitted).

[0145] In Figure 9, the absorption mask 58 is applied to the top surface 32 of the recess 30 and defines the opening 56 along the base 60 of the recess 30. However, it should be noted that in other examples, the opening 56 may be defined by applying the absorption mask 58 to another suitable surface. For example, as shown in Figure 10, the absorption mask 58 can be applied to the top surface 23 of the optical guide 10 instead of the top surface 32 of the recess 30 to define the upper end of the opening 56. The absorption mask 58 applied to the top surface 23 of the optical guide 10 extends along the top surface 23 to the extent that it can block light rays that have passed through the recess roof 34, but not to the extent that it can block light rays that receive total internal reflection from the top surface 23. For this reason, as shown in Figure 10, the absorption mask 58 extends along the top surface 23 along the entire length L of the recess 30. c The mask extends over the area and terminates within the tapered portion 50 of the optical guide 10 at a position offset from the recess 30. Thus, the masking is provided on a section of the first surface 23 that is located above the light source recess 30 and extends beyond the recess 30, limiting the angular range of light incident from multiple light sources 12 to be reflected by the first surface 23 of the optical guide 10. How an optical guide 10 with the absorption mask 58 described above can be realized using either in-mold labeling (IML) or two-shot molding will be discussed later.

[0146] The angle of the optical surface and the two-dimensional (2D) shape of the optical guide input recess wall 36 used to refract (i.e., bend) light rays can also be configured to control or limit the range of light ray angles propagating within the optical guide 10. For example, Figure 11 shows an example of a light source recess 30 having an optical coupling wall 36 shaped to define a symmetric lens, the optical coupling wall 36 having a convex curvature. In other words, in this example, the front wall 36 of the light source recess 30 is lensed. The symmetric lens is inclined or angled with respect to the vertical axis y, and the optical coupling wall 36 is inclined inward toward the light source 12 from the bottom surface 25 to the top surface 23. The symmetric lens shape is added to the input wall 36 at a sufficient angle with respect to the refracting input surface 36 so that this shape can be manufactured by injection molding. The lens in Figure 11 helps to reduce the angular range of light rays entering the optical guide 10, particularly the vertical angular range θ.

[0147] When incorporating the above-described optical guide using an intermediate layer (or middle layer) 14 of a material (e.g., fluorinated polymer (FEP)) instead of air as the top plate 10 of a system like the one in Figure 1, it is preferable to further restrict the angular range of light rays incident from the light source 12 to the optical guide 10, particularly the vertical angular range θ. The refractive index of FEP (i.e., 1.344) is higher than that of air (i.e., 1.0), which means that the angular range of light rays that cause total internal reflection beyond the critical angle at the boundary between the optical guide or top plate 10 and the intermediate layer 14 decreases from approximately 48° (when the optical guide 10 is formed of acrylic and the intermediate layer 14 is air) to 26° (when the optical guide 10 is formed of acrylic and the intermediate layer 14 is FEP material). This is shown in Figures 8a and 8b, which show the angular range of light rays that fall within the critical angular range of a system with an air intermediate layer 14 (Figure 8a) and an FEP intermediate layer 14 (Figure 8b). Therefore, in a system using an FEP intermediate layer 14 as shown in Figure 1, it is necessary to more restrict the vertical angular range of light rays injected from the light source into the light guide 10 compared to a system using air as the intermediate layer 14, so that substantially all injected light rays fall within the angular range in which total internal reflection can occur at the boundary between the light guide 10 and the intermediate layer 14. Thus, a more restricted angular range is required in a system using FEP instead of air as the intermediate layer 14, for example.

[0148] Furthermore, it is important to manage the light directed downwards from the light source (light directed towards PCB 54 to which the light source 12 is attached). If this light is not absorbed, a small amount will be reflected off the PCB surface, potentially causing undesirable stray light within the system.

[0149] With these factors in mind, Figure 12 shows that by increasing the average ray angle of the optical guide 10 using the trench injection optical system 52 as shown in Figure 6, the evanescent field can be maximized, and consequently, touch sensitivity can be maximized, without the ends of the angular range approaching the critical angle and thus increasing optical loss from the optical guide 10.

[0150] Referring to Figure 12a, curve 62 represents the light lost from the system (y-axis) for different inclination angles of the optical coupling surface (x-axis). Referring to Figures 12b and 12c, the inclination angle is defined as the inclination angle of the optical coupling surface with respect to the vertical axis y. As shown in Figure 12b, if the optical coupling surface extends vertically, the inclination angle is defined as 0°. If the optical coupling surface is inclined to extend at an angle with respect to the vertical, the inclination angle is not zero, and as shown in Figure 12c, the inclination angle of the optical coupling surface of the optical guide is 50°. Note that in Figure 12c, the light source 12 is mounted such that the light emitted from the light source 12 is directed obliquely towards the front wall 36 of the recess 30.

[0151] As shown in Figure 12a, when the tilt angle is 50° (Figure 12c), more light is lost from the upper and lower surfaces of the optical guide than when the tilt angle is 0° (Figure 12b). This is because increasing the tilt angle of the optical coupling surface from 0° to 50° reduces the angle of incidence at which light from the light source strikes the optical coupling surface. Here, the angle of incidence is defined as the angle between the light ray and the surface normal of the optical coupling surface. In the configuration with a tilt angle of 50°, the deflection of the light ray due to refraction as it passes through the optical coupling surface is greater compared to the configuration with a tilt angle of 0°, and therefore the angle of the light ray with respect to the surface normal at the upper and lower surfaces of the optical guide becomes smaller. In this way, the likelihood of at least some of the light rays falling below the critical angle and being lost from the system increases.

[0152] Curve 64 shows the light coupled to the optical guide 10 (y-axis) in microwatts (μW) at different tilt angles (x-axis), indicating that the optical power coupled to the plate 10 increases as the tilt angle increases.

[0153] Curve 66 represents the power density at the upper surface 23 of the optical guide 10 at different inclination angles. Curve 66 shows that the power density at the upper surface increases as the inclination angle increases. A higher power density at the upper surface of the optical guide indicates a stronger evanescent field, which in turn improves touch sensitivity in systems that utilize frustrated total internal reflection in a touch detection mechanism.

[0154] Regarding Figures 12a-c, understanding how the parameters described above change with the tilt angle allows for the selection of an appropriate tilt angle for the optical coupling surface 36, balancing the advantages of a stronger evanescent field and better touch sensitivity at higher tilt angles with the disadvantage of increased system losses at higher tilt angles.

[0155] Referring to Figures 13a-c, in another embodiment, in order to further improve touch sensitivity, the groove wall angle (i.e., the inclination angle of the optical coupling surface 36) is tilted, as well as the orientation of the LED is rotated in the yz plane, but this makes manufacturing more complex. Referring to Figure 13c, the light source 12 is mounted obliquely to the plane of the top plate 10 such that it emits light symmetrically about its central axis C, and its central axis C is obliquely directed toward the first surface 23 of the top plate 10. Thus, the light emitted from the light source is mainly obliquely directed toward 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 recess 30. Note that in other examples, the light source 12 may be mounted such that its central axis C is slightly offset from the axis perpendicular to the front wall 36 of the light source recess 30.

[0156] Referring to Figure 14, in another embodiment, an extruded section 68 is added to the lower end of the wedge 50 or groove to "capture" unwanted stray light from the lower end 70, avoiding sharp edges and providing support to the optical guide 10. The extruded section 68 defines a linear projection on the second surface 25 of the optical guide 10, extending away from the first surface 23. As shown in Figure 14, the linear extension of the linear projection 68 is substantially parallel to the linear extension of the light source recess 30. In this example, the linear projection 68 has a rectangular cross-section perpendicular to its linear range. In other embodiments, the shape of the projection 68 may vary. For example, the linear projection 68 may have a scalloped or similar cross-section perpendicular to its linear range. It can be seen that the taper of the optical guide 10 in Figure 14 is linear, i.e., in the tapered section 50 of this example, the distance between the first surface 23 and the second surface 25 of the optical guide 10 decreases linearly. Referring to Figure 15, in another embodiment, the taper of the optical guide 10 is not linear but decreases using facets or other continuous nonlinear functions (e.g., curves, asymmetric, splines) or a suitable combination of functions. In other words, in the embodiment of Figure 15, the distance between the first surface 23 and the second surface 25 of the optical guide 10 decreases nonlinearly in the tapered portion 50.

[0157] The main requirements or methods for optimizing trench injection optical design geometry in the horizontal plane are as follows: i. A defined target for optical power density (or evanescent field) is achieved across the entire upper surface 23 of the optical guide 10. ii. A defined uniformity target of optical power density (typically μW / mm²) across the entire active area of ​​the touch surface 23 of the optical guide 10. 2Achieves (units). As described above, the active area of ​​the optical guide 10 is the area of ​​the touch surface 23 where the system can detect a touch. For example, in the case of a touchscreen, the active area is generally a large rectangular area. In the case of a finger slider groove (i.e., a portion of the optical guide upper surface 23 that includes one or more grooves that function as a finger guide), the active area can be a long and narrow area 72, as shown in Figure 16. Uniform optical power density within the active area of ​​the optical guide 10 is beneficial because it improves the uniformity of touch response across the entire active area. iii. Minimize the number of light sources 12 in order to achieve the specified uniformity target of light power density across the entire active area of ​​the touch surface 23. iv. Achieve the specified uniformity target of optical power density across the entire active area of ​​the touch surface 23 at the shortest possible distance from the light source 12. v. Minimize the distance between the rear surface 38 of the trench injection optical system 52 (i.e., the back surface 38 of the light source recess 30) and the active region of the optical guide 10.

[0158] The optical shape of the trench injection optical system 52 is beneficial for improving the light distribution across the entire upper surface 23 of the optical guide.

[0159] In an optical guide 10 using a trench injection optical system 52 as shown in Figure 5 or 6, the horizontal light distribution across the upper surface 23 of the 2D curved shape of the optical guide 10 is mainly derived from the light distribution of the LEDs and the layout of the light source array, i.e., the arrangement of the light sources 12 located within the recesses 30 of the trench injection optical system 52.

[0160] The light source array layout refers to the spacing and orientation of the light sources 12 within the light source recess 30. The trajectory of the LED output can be further varied by adjusting the shape of the light source recess 30, particularly the shape of the optical coupling surface 36. Referring to Figure 17a, an embodiment of the trench injection optical system 52 with a flat, planar optical coupling surface 36 is shown. Referring to Figure 17b, an embodiment of the trench injection optical system 52 with a curved optical coupling surface 36 is shown. In particular, the optical coupling surface 36 in the embodiment of Figure 17b is curved with respect to the x-direction, defining a curve in the xz-plane.

[0161] Generally, the further the LED array is from the touch geometry, the better the uniformity of light from the light source 12 into the optical guide 10. In other words, as the distance of the trench injection optics 52 from the light source 12 increases, the uniformity of light within the optical guide 10 improves, and consequently, the uniformity of light in the active region improves as the distance of the active region from the light source 12 increases.

[0162] However, in many applications, for aesthetic reasons in the final touchscreen product, or due to space considerations / constraints, it is advantageous to bring the active area closer to the light source 12 of the optical guide 10, and in some cases as close as possible. Ideally, the separation of the array and geometry should be minimized, and the spacing between adjacent light sources 12 should be maximized so that the uniformity target is achieved.

[0163] In the embodiment, masking (i.e., an absorbing mask layer 58 or element that absorbs light) is used to absorb light rays that strike the upper surface 23 or lower surface 25 of the optical guide 10. In other words, by masking the area of ​​the first surface (or upper surface) 23 and / or the second surface (or lower surface) 25, it is possible to prevent light from multiple light sources 12 in the groove or recess 36 from being totally reflected within the optical guide 10.

[0164] The masking layer 58 or elements can be positioned to control their location (for example, the position of the top surface 23 from which light rays can be reflected), so that the light rays emitted from the light source 12 are absorbed at an angle such that they are not totally reflected from the top surface 23, thereby controlling light leakage from the top surface 23 of the light guide 10. Since the intensity distribution of the light source changes with the angle in the xz plane, the edges of the mask may also change accordingly with the angle in the xz plane.

[0165] In embodiments where no lens is used to couple the light emitted from the light source 12 to the optical guide 10, the trench injection optical system 52 approach described above allows for flexibility in the arrangement of the light source components. This is because, in that case, the precise position and orientation of each light source 12 within the recess 30 becomes less important than when the light from the light source 12 propagates through a lens before entering the optical guide 10.

[0166] Therefore, by not using lenses, the influence of variations in the arrangement of light source components (e.g., due to assembly tolerances) on the optical performance (e.g., irradiance distribution or optical efficiency) of the trench injection optical system array 52 can be reduced.

[0167] The method for injecting light into the optical guide 10 using the pocket injection optical system (PIO) 74 is described below.

[0168] Examples of pocket injection optics 74 are shown, for example, in Figures 7, 18, 19, and 20.

[0169] The pocket injection optical system 74 is constructed using complete 3D geometry to control the horizontal and vertical angular distribution of light from the light source 12. For this purpose, the 3D shape of the light source recess 30, where the light source 12 is positioned, is coupled to the optical guide 10 and designed to control the angular distribution of light moving within the optical guide 10. This optical design of the pocket injection optical system 74 controls the vertical (y-dimension) light distribution in a similar manner to the trench injection optical system 52, providing further control over the horizontal (x-dimension) intensity distribution. This control can be used to compensate for differences in vertical intensity distribution due to angle, and can also be used to influence the convergence or divergence of the light distribution across the entire surface 23 of the active region of the optical guide 10.

[0170] First, considering the vertical profile of the pocket injection optical system 74 in the yz plane, the main requirements for optimizing the design geometry of the pocket injection optical system in the vertical plane are the same as those for the trench injection optical system 52, but for clarity and completeness, they are repeated below. i. Maximize the optical coupling efficiency to the optical guide 10. ii. Maximize the optical power density (or evanescent field) on the upper surface 23 of the optical guide 10. iii. Minimize light loss in the optical guide 10 (mainly due to loss from the upper surface 23 and lower surface 25 of the optical guide). It should be noted that light lost from the system through the roof portion 34 and the rear wall (or back wall) 38 of the recess 30 of the optical guide 10, or light hitting the printed circuit board (PCB) 54 below the light source 12, is not included in the following analysis. iv. Minimize the distance between the rear wall (or back wall) 38 of the trench injection optical system 52 and the active region of the optical guide 10 (i.e., the region of the optical guide 10 in which touch to the upper surface 23 of the optical guide 10 can be detected by the system).

[0171] All the factors described above for the trench injection optical system 52 (mainly related to the numerical aperture of the optical system and the refractive index of the optical guide material) also apply to the pocket injection optical system 74, but for brevity, we will not repeat the explanation. Here, we will highlight only the main additional elements that can be used to control or limit the range of vertical ray angles propagating within the optical guide 10, thereby optimizing the important requirements described above.

[0172] The angle, shape, and taper of the refractive input surface 36 (also called the optical coupling surface 36 of the light source recess 30) can be used to control the vertical angular range of the light ray propagating within the optical guide 10. As described in relation to the trench injection optical system 52, as the incident angle of the light ray undergoing total internal reflection at the boundary between two regions of materials with different refractive indices approaches the critical angle, the depth of the evanescent field, i.e., the penetration of the evanescent field, increases. Therefore, configuring the injection optical systems 52, 73 so that the light ray propagates within the optical guide 10 at an angle as close to the critical angle as possible increases the depth of the evanescent field, resulting in improved touch sensitivity of the system that utilizes total internal reflection frustrated in the touch detection process.

[0173] As explained in relation to Figures 12b and 12c, increasing the angle of the optical coupling surface 36 with respect to the vertical (y) axis (i.e., the inclination or tilt of the refractive input surface 36) can increase the evanescent field on the upper surface 23 of the optical guide 10 by causing the light from the light source 12 within the optical guide 10 to propagate as close as possible to the critical angle. Similarly, the evanescent field on the upper surface 23 of the optical guide 10 can be increased by including a tapered section 50 in the optical guide 10 between the thick section 46 containing the light source recess 30 and the thin section 48, and the evanescent field can also be increased by adjusting the taper of the tapered section 50, or by a combination of these. On the other hand, in the pocket injection optical system 74, these parameters can be changed on the side of the optical coupling surface 36 extending toward the rear of the light source recess 30, for example, to compensate for changes in the intensity distribution of the light source.

[0174] Figure 18a shows an embodiment of a pocket injection optical system 74 that can be incorporated into, for example, the top plate 10 of a touch detection system as shown in Figure 1.

[0175] Similar to the arrangement of the trench injection optical system 52 in Figures 5 and 6, the pocket injection optical system 74 in Figure 18a includes a recess or cavity 30 below the optical guide defined by the top plate 10. The recess 30 has an optical coupling surface 36 which functions as a refractive input surface for coupling light from a light source 12 located within the recess 30 into the body of the top plate 10.

[0176] In the embodiment shown in Figure 18a, the refractive input surface 36 defines a curved path between its first end 76 and second end 78, and defines the length of the curve between the first end 76 and the second end 78. The refractive input surface 36 extends around the light source 12 from the first end 76 to the second end 78, partially surrounding the light source 12. The front surface of the light source 12 defines the light-emitting region 40 of the light source that faces the refractive input surface 36 of the recess 30. When in use, light is emitted from the light-emitting region 40 of the light source 12, passes through the refractive input surface 36, and enters the body of the top plate 10, where the light undergoes total internal reflection.

[0177] Referring further to Figure 18a, the height of the refractive input surface 36 (i.e., the distance between the upper end 80 and the lower end 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. In particular, in the embodiment of Figure 18a, the height of the refractive input surface 36 increases from the minimum height at the first end 76 and the second end 78 to the maximum height at the central position along the length of the refractive input surface 36 between the first end 76 and the second end 78.

[0178] In the configuration shown in Figure 18a, the inclination or slope of the refraction input surface 36 also changes along the curved path between the first end 76 and the second end 78 of the refraction input surface 36. In particular, the inclination of the refraction input surface 36 increases from the first end 76 to the center position along the curved length of the refraction input surface 36. Similarly, the inclination of the refraction input surface 36 increases from the second end 78 to the center position along the curved length of the refraction input surface 36.

[0179] In other examples, the height and inclination of the refractive input surface 36, and the changes in the height and inclination of the refractive input surface 36 between the first end 76 and the second end 78, may differ from the arrangement in Figure 18a. In some examples, the height and inclination of the refractive input surface 36 may be constant over the curvature length of the refractive input surface 36. The parameters defining the shape and arrangement of the refractive input surface 36 can be changed, for example, according to the parameters of the associated light source 12.

[0180] Figure 18b shows how the pocket injection optical system 74 of Figure 18a is incorporated into the top plate 10. The top plate 10 has a tapered section 50 between a thick section 46 incorporating the light source recess 30 and a thin section 48 of the top plate 10. In the example of Figure 18b, the lower surface 25 of the top plate 10 surrounding the light source recess 30 is inclined upward toward the upper surface 23 of the top plate 10 from the thick section 46 to the thin section 48, defining the tapered section 50 of the top plate 10. In the embodiment of Figure 18b, the inclination of the lower surface 25 is greater near the center of the curvature of the refractive input surface 36 than the first end 76 and second end 78 of the refractive input surface 36. Therefore, the taper of the top plate 10 is greater in front of the light source 12, particularly in the light-emitting region 40 of the light source 12, than on the sides of the light source 12.

[0181] Returning to Figure 7, the pocket injection optical system 74 of this embodiment has a light source recess or cavity 30 with multiple refractive input surfaces 36. The pocket injection geometry provides basic control over the vertical light distribution, similar to the trench injection optical system 52, but allows for further control over the horizontal intensity distribution. This not only compensates for differences in vertical intensity distribution due to angles, but can also influence the convergence or divergence of the light distribution across the entire surface of the active area where touch can be detected. It should be noted that different touch shapes may require a pocket injection optical system 74 with a narrow or wide light distribution.

[0182] Figure 41a shows a pocket injection optical system 74 that provides a narrow light distribution. The pocket injection optical system 74 in Figure 41a includes a single refractive input surface 36 with a convex curvature in the xz plane. The horizontal distribution of light emitted from the light source 12 (represented by multiple rays 79 in Figure 41a, but only two rays are labeled in Figure 41a for clarity) is shaped by the refractive input surface 36 as it passes through, providing a narrow light distribution within the optical guide 10. Such a narrow light distribution may be suitable for elongated and narrow active regions, such as those used in a slider 72 as shown in Figure 16.

[0183] Figure 41b shows a pocket injection optical system 74 that distributes light over a wide area. The pocket injection optical system 74 in Figure 41b has a configuration similar to that shown in Figure 7 and features three refractive input surfaces 36 that function to shape the horizontal distribution of light from the light source 12 (represented by multiple rays 79 in Figure 41b, but labeled only two for clarity) to provide a wide light distribution within the optical guide 10. Such a wide light distribution may be suitable for use in a dial setup, for example, as shown in Figure 28.

[0184] The example in Figure 7 includes a first lateral refracting input surface 84, a second lateral refracting input surface 86, and a central refracting input surface 88. The light source 12 is positioned within the recess 30, and light is coupled to the body of the top plate 10 via the refracting input surface 36. The light source recess 30 is provided in the first relatively thick section 46 of the optical guide 10. The tapered section or wedge 50 of the optical guide 10 connects the first section 46 to a second relatively thin (or narrow) section 48 of the optical guide 10, which lies between the recess 30 and the narrow section 48. In the narrow section 48, the distance between the first surface 23 and the second surface 25 is substantially constant, but shorter than the distance between the first surface 23 and the second surface 25 in the recess 30.

[0185] The first lateral refraction input surface 84 extends along a curved path between its first end 90 and second end 92. The first end 90 of the first lateral refraction input surface 84 is positioned on the first side 94 of the light source 12 when the light source 12 is placed in the recess 30 for use. The central refraction input surface 88 extends along a curved path between its first end 96 and second end 98, connecting the first lateral refraction input surface 84 and the second lateral refraction input surface 86. The second lateral refraction input surface 86 extends along a curved path between its first end 100 and second end 102. The second end 102 of the second lateral refraction input surface 86 is positioned on the second side 104 of the light source 12 when the light source 12 is placed in the recess 30 for use. The central refraction input surface 88 is positioned directly in front of the front surface of the light source 12, and the light-emitting area 40 of the light source 12 faces the central refraction input surface 88.

[0186] In this example, the two side refractive surfaces 84 and 86 are arranged symmetrically with respect to the central refractive input surface 88 and adjacent to the central refractive input surface 88. As can be seen from Figure 7, in this example, the central refractive input surface 88 has a different curvature than the side refractive surfaces 84 and 86.

[0187] In this way, light emitted from the light source 12 in a generally forward direction is coupled to the body of the top plate 10 via the central refraction input surface 88, and light emitted from the light source 12 in a generally sideways direction is coupled to the top plate 10 via the first side refraction input surface 84 and the second side refraction input surface 86. By providing side refraction input surfaces 84, 86 or wings extending from the central refraction input surface 88, the intensity distribution of light from the light source 12 within the optical guide 10 can be controlled more appropriately.

[0188] The refractive input surfaces 84, 86, and 88 are inclined inward toward the light source 12, from the lower surface 25 of the optical guide 10 to the upper surface 23 of the optical guide 10, as shown, for example, in Figures 12c and 15. In other words, the walls of each refractive input surface form an angle with respect to the plane of the top plate 10, so that the refractive input surfaces 84, 86, and 88 and the second surface 25 of the top plate 10 form an obtuse angle within the top plate 10.

[0189] As explained in relation to Figure 12c, by providing inclined input surfaces 84, 86, and 88, it becomes possible to control the vertical angle range of the light rays propagating within the optical guide 10. In particular, this can be used to bring the angle of the light rays closer to the critical angle in order to improve the penetration of the evanescent field at the upper surface 23 of the optical guide 10 and improve touch sensitivity.

[0190] The curvature along the lengths of the refractive input surfaces 84, 86, and 88 allows for control over the horizontal spread of the light rays in the xz plane of the optical guide 10. Different shapes, particularly different horizontal curvatures of the first side refractive input surface 84, the second side refractive input surface 86, and the central refractive input surface 88 in the xz plane, allow for more appropriate control over the horizontal distribution of light rays from the light source 12 within the optical guide 10.

[0191] In the examples of Figures 7 and 20, the curvature of the central refraction input surface 88 defines a substantially elliptical shape in the horizontal plane of the optical guide 10, i.e., the xz plane. In particular, the central refraction input surface 88 defines a semi-ellipse in the horizontal plane, and the horizontal distance in the x-dimension between the first end 96 and the second end 98 of the central refraction input surface 88 defines the minor axis of the ellipse. The central refraction input surface 88 is configured to diffuse the light emitted from the light source 12 and incident on the central refraction input surface 88 into the horizontal plane (xz) of the optical guide.

[0192] The curvature of the first and second refractive input surfaces 84 and 86 in the horizontal plane is selected to appropriately redirect light rays striking these surfaces. In the embodiments of Figures 7 and 20, the first and second refractive input surfaces 84 and 86 are configured to restrict the light striking these surfaces from spreading horizontally within the optical guide 10, as shown in Figure 20.

[0193] It should be noted that the curvature of the refractive input surfaces 84, 86, and 88 may vary in other embodiments. For example, one or more of the refractive input surfaces 84, 86, and 88 may have conical curvature or define a spline. Figure 19 shows a top plate 10 incorporating two pocket injection optics 74 having a shape similar to that of Figure 7, and shows that an absorption mask layer 58 may be provided on the upper surface 23 of the optical guide 10 to prevent stray light from the light source 12 from leaking out of the optical guide 10, similar to the mask 58 in Figures 3, 4, and 10. As described above, masking as shown in Figure 19 is used to control light leakage from the optical guide 10, in particular to block light rays that would pass directly through the upper surface 23 of the optical guide 10 and exit because they fall below the critical angle in the masked area. In the embodiment shown in Figure 19, the front end 106 of the mask 58 is interrupted before the first totally reflected ray hits the upper surface 23 of the optical guide surface, defining the start of the active region of the optical guide 10 where touch to the upper surface 23 of the optical guide 10 can be detected. In other words, almost all of the light from the light source 12 that hits the masked region of the upper surface 23 of the optical guide 10 is below the critical angle and would escape from the optical guide 10 if the mask 58 were not present. Therefore, the mask 58 does not absorb the "useful" light that would totally reflect at the upper surface 23 if the mask 58 were not present. As mentioned above, one possibility is to mask only the light in the "working" range for detection and not mask the other light so that the other light can be used for other purposes (for example, the masking works only for infrared light and visible light is transmitted).

[0194] In the example in Figure 19, the masking 58 is shown to extend across two pocket injection optics 74. In some examples, it will be understood that the masking 58 may be provided on all pocket injection optics 74 of the optical guide 10, or on only some of the pocket injection optics 74 of the optical guide 10. Furthermore, in some examples, the masking may extend only partially across some or all of the pocket injection optics 74 of the optical guide 10. The main requirements or techniques for optimizing the design geometry of the pocket injection optics in the horizontal plane (xz) are the same as those described for the trench injection optics 52 and are as follows: i. Achieve the defined optical power density (or evanescent field) target across the entire upper surface 23 of the optical guide 10. ii. The optical power density (μW / mm²) across the entire active area of ​​the touch surface 23. 2 The uniformity target defined by () is achieved (in the case of a screen, it is a wide rectangular area, but in the case of a finger slider groove, it is a long and narrow area. See Figure 16). iii. Use the minimum number of light sources 12 to achieve the specified uniformity target. iv. Achieve the specified uniformity target at the shortest possible distance from the light source 12. v. Minimize the distance between the back surface 38 of the pocket injection optics 74 and the active region.

[0195] On the other hand, horizontal profile control in the 3D geometry of the pocket injection optical system 74 allows for direct control of the horizontal intensity distribution from the light source 12 using key control parameters.

[0196] In the pocket injection optical system 74, one or more refractive input surface optical profiles can be used to broaden or parallelize the light distribution to suit the required application. Figure 20 shows the multiple refractive input surface shapes of Figures 7, 19 and 20, which have three different parts (first side refractive input surface 84, second side refractive input surface 86 and central refractive input surface 88) with different geometric profiles, and these are incorporated into the top plate 10 of a touch-sensitive screen where a wide light distribution is required.

[0197] Figure 21a shows the pocket injection optical system 74 of Figure 20, illustrating how light rays from the light source 12 propagate through the optical guide 10, providing a broad intensity distribution in the horizontal (xz) plane within the active region of the optical guide 10.

[0198] Figure 21b shows the narrow horizontal intensity distribution output from the light source 12 alone in the configuration shown in Figure 21a, before passing through the refractive input surfaces 84, 86, and 88 of the pocket injection optical system 74. Figure 21c shows the intensity distribution of light from the light source 12 within the optical guide 10 in the active region of the optical guide 10, located in the relatively thin region 48 of the optical guide 10, after passing through the refractive input surfaces 84, 86, and 88 of the pocket injection optical system 74. As can be seen from Figure 21c, the refractive input surfaces 84, 86, and 88 broaden the horizontal intensity distribution of light from the light source 12, providing a wide intensity distribution in the horizontal plane as shown in Figure 21c. Therefore, Figure 21c shows the resulting wide intensity distribution in the horizontal (xz) plane of the optical guide 10, generated using the pocket injection optical system 74 of Figure 21a.

[0199] It can be seen that other shapes may be used for the refractive input surface of the pocket injection optical system 74 to provide different horizontal light distributions as needed or desired, in order to match the touch shape of a specific touchscreen application.

[0200] The shape of the refractive input wall (i.e., refractive input surface) of the pocket injection optical system 74 allows for direct control of the xz intensity distribution within the optical guide 10, improving the uniformity of the pocket injection optical system array, especially when close to the light source 12. Each array of the pocket injection optical system 74 can customize the horizontal and vertical shape of the light from the associated light source 12, resulting in improved uniformity and controllability of the horizontal intensity distribution compared to an equivalent trench injection optical system array 52. ​​In general, the pocket injection optical system 74 approach improves the accuracy of the angular light distribution, allowing the same uniformity to be achieved with fewer light sources 12.

[0201] A further advantage of the pocket injection method is that the available light power from the light source 12 can be used more efficiently (resulting in lower power consumption) because the light is distributed to where it is needed, i.e., to the active region of the light guide 10, and no light is wasted in regions of the light guide 10 where light is not needed.

[0202] Because the pocket injection optics system 74 is compact, it offers greater flexibility in the placement of the light source 12, and provides more space for other optical and mechanical functions, electrical components, and other electrical parts.

[0203] Furthermore, if one light source 12 in the array of pocket injection optics 74 fails, the combined light distribution will be less affected compared to the array of trench injection optics 52, since all pocket injection optics 74 can have the same light distribution. Similarly, the differences between the unique LEDs in the array of pocket injection optics 74 are also not as significant. For example, if the light output of one light source 12 in the array of pocket injection optics 74 differs significantly from the light output of an adjacent light source 12, the impact on the light distribution may be smaller compared to a similar scenario in the trench injection optics 52, which has an array of light sources 12.

[0204] In some cases, it is desirable to provide a combination of trench injection optics 52 and pocket injection optics 74 in a single device. For example, a device may have separate “active regions” that are masked from each other (effectively creating multiple devices or sub-devices), each using a different optical type to match the overall function of the associated active region. For other device types, it may be desirable to use both trench injection optics 52 and pocket injection optics 74 to achieve effective light propagation throughout the device, especially when the shape of the active region is complex.

[0205] Those skilled in the art will understand that the placement of the light source 12 relative to the refractive input surfaces 36, 84, 86, and 88 affects the shape provided by the refractive input surfaces 36, 84, 86, and 88 of the pocket injection optical system 74. Therefore, this point must be considered when placing the light source 12 within the light source recess 30. There are certain key advantages to using the shapes of the trench injection optical system 52 or pocket injection optical system 74 described above in small surface-mount device (SMD) light source (e.g., LED) packages. The smaller the light source package, the smaller the volume of the light source recess 30 required below the optical guide 10, and the less impact the light source 12 and the associated recess 30 have on other functional elements in the assembly. However, it has been found that the light distribution from some LEDs 12 is not ideal, which can lead to reduced efficiency and uniformity.

[0206] The applications of light sources 12 (especially LEDs) used in touchscreens can generally be divided into two groups depending on the angular distribution of light intensity. LEDs 12 with a wide horizontal angular range and a narrow vertical angular range are ideal for applications with a large illumination area, such as screens, domes, and dial shapes. In these cases, the intensity distribution needs to have a "soft" edge so that a uniform irradiance distribution is generated by overlapping with adjacent pocket injection optics 74.

[0207] LED12, with its narrow horizontal and vertical angular range, is ideal for applications with a narrow illumination area, such as sliders and toggles. In such cases, the intensity distribution of LED12 can have a "hard edge" because the shape is typically illuminated by at least one pocket injection optical system 74 at each end of the shape, eliminating the need to superimpose the light distributions of adjacent LED12s.

[0208] Note that the forward direction of the intensity distribution is aligned along the z-axis (defined using the coordinate system in Figure 5), and the shown intensity distribution is symmetric with respect to the yz-plane and the xz-plane.

[0209] For example, SMD LEDs currently on the market that are suitable for use in pocket injection optics 74 generally fall into two groups.

[0210] Referring to Figure 22a, the wide-angle SMD LED has a broad "batwing" shaped intensity distribution in both the horizontal (xz) and vertical (xy) planes.

[0211] The broad, gently sloping "soft edge" of the horizontal profile in Figure 22a provides a good starting point for achieving proper uniformity in the horizontal plane, which can be further improved when combined with a pocket injection optical system 74 having a suitable horizontal lens profile (i.e., a suitable shape in the xz plane for proper horizontal beam shaping) on ​​the refractive input surfaces 36, 84, 86, 88.

[0212] On the other hand, in the vertical profile of Figure 22a, even if the horizontal profiles of the refractive input surfaces 36, 84, 86, and 88 are appropriate, the broad distribution does not adequately correspond to the numerical aperture of the pocket injection optical system 74. As a result, the optical coupling efficiency to the optical guide 10, which incorporates the pocket injection optical system 74 and the LED light source 12, decreases.

[0213] Referring to Figures 22b and 23b, the narrow-angle SMD LED has a narrow intensity distribution in both the horizontal (xz) and vertical (xy) planes. Referring to Figure 23a, this type of LED uses a circular lens to focus some of the light from the LED chip. The light that escapes this focusing effect creates a "halo" of high-angle rays surrounding the narrow-angle cone rays at the center. By appropriately adjusting the distance of the LED 12 from the refractive input planes 36, 84, 86, and 88, the narrow cone rays from the LED 12 can be made to correspond to the numerical aperture of the pocket injection optical system 74 in the vertical plane. In the horizontal plane, the narrow cone rays can be broadened using a cone profile on the pocket injection optical system 74, which has been shown to yield the desired light distribution within the optical guide 10. On the other hand, the halo of light emitted from the sidewalls 108 of the LED 12 reduces the optical coupling efficiency and creates problems with stray light management in the assembly.

[0214] With the above in mind, Figure 24a shows the design of the hyperelliptical LED package (HE-LED) 109. Package 109 can be used in combination with, for example, a pocket injection optical geometry without optical output, in which case the refractive input surface 36 does not have a lensing effect on light received from the light source 12 (called 0%-PIO). Package 109 can also be used in combination with other injection optical geometries (e.g., those with optical output), in which case the front wall 36, through which light passes when incident from the light source 12 into the optical guide 10, exerts a lensing effect. For example, the front wall 36 is configured to provide a lensing effect in the horizontal, vertical, or both directions, thereby improving the horizontal and / or vertical light distribution within the optical guide 10 as needed.

[0215] The packaged light-emitting diode 109 in Figure 24a includes a light-emitting diode die or chip 110 and a lens 112. The lens 112 has a cylindrical shape and significantly improves the optical coupling efficiency between the light source 12 and the optical guide 10, as well as the uniformity of light within the optical guide 10. The light emitted through the cylindrical lens 112 has a narrow angular distribution along the first axis and a wide angular distribution along the second axis perpendicular to the first axis. Therefore, the packaged light-emitting diode 109 in Figure 24a is ideal for touchscreen applications.

[0216] As shown in Figure 24a, in this example, the cylindrical lens 112 is formed as a truncated, substantially flattened elliptic lens 112a in a body having two first truncations 114 and one second truncation 116. The two first truncations 114 are perpendicular to the axis A of the flattened ellipsoid and equidistant from the longest semi-axis of the flattened ellipsoid. The second truncation 116 is parallel to the axis A of the flattened ellipsoid and perpendicular to the two first truncations 114. In other examples, the shape of the lens 112 differs from that of Figure 24a, for example, defining a flattened ellipsoid of spheroids.

[0217] The position of the LED chip 110 of package 109 in Figure 24a on the support substrate is almost the same as the position of the LED chip 110 in the arrangement in Figure 23a (not visible in Figure 24a) on the same support substrate 118, and the lens 112a in Figure 24a is directly mounted on the light-emitting surface of the light-emitting diode die. It can be seen that the light-emitting diode die of package 109 in Figure 24a is close to the second truncated portion 116.

[0218] Figure 42a shows another example of the HE-LED package 109. Similar to the example in Figure 24a, the package 109 in Figure 42a includes a light-emitting diode die or chip (not shown) and a cylindrical lens 112. The position of the LED chip in the package 109 in Figure 42a on the support substrate 118 is the same as that of the LED chip 110 in the arrangement in Figure 23a on the support substrate 118. However, in the example of Figure 42a, the cylindrical lens 112 takes the form of a truncated aspherical lens 112b. In particular, the cylindrical lens 112b is formed as an aspherical lens in a deformed ellipsoid, which comprises two first truncations 114 and one second truncation 116. The two first truncations 114 are perpendicular to axis A of the deformed ellipsoid and equidistant from the longest semi-axis of the deformed ellipsoid. The two first truncations 114 are parallel to each other with respect to the two axes of the flattened ellipsoid. The second truncation 116 is parallel to the other axis A of the flattened ellipsoid and perpendicular to the two first truncations 114. The lens shape in Figure 42a is created by sweeping a vertical variable radius along a horizontal spline path. As can be seen from Figure 42a, the lens 112b is more curved in the center (i.e., the first short radius of curvature R1) and less curved on the sides themselves and toward the sides (i.e., the second long radius of curvature R2). In this example, because the lens surface on the sides is further away from the center, less power is required to make the divergent light horizontal on average.

[0219] Figures 24b and 42b show the light intensity distribution from package 109 in Figures 24a and 42a, respectively, in both the horizontal (xz) and vertical (xy) planes. From Figures 24b and 42b, it can be seen that package 109 in Figure 42a, using the aspherical lens 112b, provides a narrower horizontal light distribution than package 109 in Figure 24a, using the flattened elliptical lens 112a. Thus, it will be understood that the choice of lens 112 can affect the angular distribution of light from package 109.

[0220] Figures 25a and 25b show the HE-LED package 109 of Figure 24a combined with a pocket injection optical system 74 similar in shape to that of Figure 18a. Figure 25c shows that the HE-LED lens 112 traces a 180-degree arc from the die in the horizontal plane to capture the entire bandwidth of light from the LED die, improving optical coupling efficiency. Figure 25d shows the intensity distribution of light from the light source 12 within the optical guide 10 in the active region of the optical guide 10, located in the thin region 48 of the optical guide 10. By more efficiently capturing the available light from the LED die, stray light that needs to be suppressed and managed within the system is reduced.

[0221] Figure 26 shows that the "soft edge" and smoother HE-LED intensity distribution significantly reduce the distance forward (i.e., in the z-direction) from the pocket injection optics 74, achieving a 10% uniformity target (represented by line 119 in Figure 26) compared to the configuration in Figure 7. In other words, using the HE-LED package 109 allows for a more uniform light intensity distribution near the pocket injection optics 74 within the optical guide 10. In the configuration in Figure 7, since the HE-LED package 109 is not used, the intensity distribution is discontinuous, and a longer optical guide 10 must be traversed to achieve the same light intensity uniformity.

[0222] Figure 27 shows how the optical power of the HE-LED can be increased without negatively affecting the angular distribution characteristics of the HE-LED109 by expanding the LED die size along the horizontal axis.

[0223] The method for delivering light to the optical guide 10 (for example, the top plate 10 arranged as shown in Figure 1) has already been described. Next, we will explain how to manage the light in the optical guide 10. In particular, we will explain how to efficiently manage the light within the optical guide 10 in order to control where the light reaches or does not reach.

[0224] One way to manage the light within the light guide 10 is to use a dispersion pattern of light injection "points" to create an active lighting zone, or active area, on the touchscreen.

[0225] Another approach involves using light-absorbing properties (such as paints, overmolding, or in-mold labels (IML)) to limit the angular range of the ray angle, or to isolate optical geometric elements to control inactive areas (i.e., to provide optically inactive zones).

[0226] Considering the initial approach, an "active region" can be created by arranging one or more pocket injection optics 74 in a pattern around a given optical guide shape. In different embodiments, the pocket injection optics 74 can be combined in different patterns or array configurations (e.g., square, rectangular, circular, and many other variations) to efficiently and uniformly distribute light throughout the active region. For example, referring to Figure 16, a first active region 120 can be created using a circular array of wide-angle pocket injection optics 74a to illuminate the shape of the D-pad (i.e., the directional pad). Near the same optical guide 10, a second active region 122 can be created using a pair of narrow-angle pocket injection optics 74b located at both ends of a touch region defining a single slider geometry.

[0227] The main elements used to optimize the patterned light distribution in the active region are as follows: • Unique pocket injection light intensity distribution (may be fixed) • Pattern used to position the pocket injection optical system 74 • Spacing of pocket injection optics 74 within the pattern • Direction of the pocket injection optical system 74

[0228] The same optical targets (as described above) are applied to the active region. Specifically, they are as follows: · Maximize the optical power efficiency supplied to the active region · Optimize the optical uniformity to be as close as possible to the target percentage range · Minimize the distance from the pocket injection optical system 74 to the edge of the touch sensing region (i.e., the region where the target uniformity is achieved) · By using the minimum number of pocket injection optical systems 74 possible, space is secured for other components within the assembly and power consumption is minimized

[0229] Here, an example of creating an active region using the layout geometry of multiple pocket injection optical systems 74 will be described.

[0230] FIG. 28 shows a circular 3D "dial" light guide shape that couples light into the light guide 10 using multiple pocket injection optical systems 74 (only one is labeled in FIG. 28 for clarity). The dial - type light guide 10 of FIG. 28 can form the top plate of a double - plate arrangement similar to FIG. 1 and has a curved profile contour.

[0231] The light guide 10 of FIG. 28 has an upper wall 124, side walls 126, and a lower wall 128. The upper wall 124 defines the central region of the light guide 10, and this central region is, in plan view, substantially planar and generally circular. The side walls 126 extend downward and radially outward from the periphery 130 of the upper wall 124 to the lower wall 128.

[0232] Light is injected into the light guide 10 from multiple light sources 12 (only one light source is shown in FIG. 28 for clarity) disposed in multiple light source recesses 30 (only one light source recess is labeled in FIG. 28 for clarity). Each light source 12 is disposed at the peripheral portion 132 of the light guide 10 and undergoes total internal reflection within the light guide 10.

[0233] In this example, the optical waveguide 10 includes 16 light source recesses 30, and one light source 12 is accommodated in each recess. It will be understood that in other examples, the number of light sources 12 and associated light source recesses 30 can be more or less than this.

[0234] Each light source recess 30 in this example utilizes the shape of the pocket injection optical system 74 shown in FIG. 7. Similar to the arrangement of FIG. 7, each light source recess 30 is defined by a depression on the lower side of the optical waveguide 10 and is provided in the thick section 46 of the optical waveguide 10. The tapered portion 50 of the optical waveguide 10 joins the thick section 46 of the optical waveguide 10 that includes the light source recess 30 and the thin section 48 of the optical waveguide 10. In this way, the side wall 126 and the upper wall 124 of the optical waveguide 10 define the thin section 48 of the optical waveguide 10, and the lower wall 128 defines the thick section 46 and the tapered portion 50 of the optical waveguide 10.

[0235] The light sources 12 and associated light source recesses 30 are arranged at equal intervals around the peripheral edge 132 of the optical waveguide 10. Each light source 12 is arranged to face inward toward the central axis C of the optical waveguide 10, and each light source 12 emits light toward the central axis C.

[0236] The arrangement in Figure 28 provides the optical guide 10 with a touch detection area 134 (i.e., an active zone or region) in which a touch can be detected when the optical guide 10 is incorporated into a suitable touch detection arrangement, such as a double-plate arrangement similar to that in Figure 1. In the example in Figure 28, the touch detection area 134 is defined by the side walls 126 and top wall 124 of the optical guide 10, but in other embodiments, the active region 134 may also surround at least a portion of the bottom wall 128 of the optical guide 10. In any case, the light sources 12 of the optical guide 10 are located on the outer perimeter 136 of the active zone or region 134. In this example, the outer perimeter 136 defines a circle in plan view. In other examples, the shape of the outer perimeter 136 can be changed to define an ellipse, rectangle, or square in plan view, but is not limited to these. The light sources 12 are spaced apart so that a substantially uniform light distribution is formed in the active region 134 of the top plate 10. Figures 29a-d show the uniformity of light within the dial light guide 10 having a similar arrangement to that in Figure 28. Specifically, Figure 29a shows the light guide 10 from Figure 28 with 16 light sources 12 (not visible in Figure 29a), Figure 29b shows a light guide 10 similar to the light guide 10 in Figure 28, but with 12 equally spaced light sources 12 instead of 16, and Figure 29c shows a light guide 10 similar to the light guide in Figure 28, but with 8 equally spaced light sources 12 instead of 16. In Figures 29a-c, the bright and dark areas of the light guide 10 indicate the irradiance within the light guide 10, with bright areas indicating high irradiance and dark areas indicating low irradiance. As can be seen from Figures 29a-c, the irradiance of light within the light guide 10 is generally not uniform within the lower wall 128 of the light guide 10, with bright and dark areas appearing alternately (related to the spacing between the light sources 12).

[0237] Figure 29d shows the uniformity of optical power density at the side walls 126 of each optical guide 10 in Figures 29a-c at various angular positions around the central axis C of the optical guide 10. In Figure 29d, curve 138 represents the optical guide arrangement in Figure 29a, curve 140 represents the optical guide arrangement in Figure 29b, and curve 142 represents the optical guide arrangement in Figure 29c. 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%. With this in mind, Figure 29d shows that while the arrangements in Figures 29a and 29b achieve a uniformity of + / -10% optical power density within the side walls 126, the arrangement in Figure 29c, which uses fewer light sources 12 for illumination, does not fall within this uniformity range at all positions on the entire side wall 126.

[0238] Next, looking at Figure 30, another example is shown in which an active region is created using multiple pocket injection optics 74 (only one of which is labeled in Figure 30), this time a rectangular flat optical guide 10. Similar to the optical guide 10 in Figure 28, the optical guide in Figure 30 can be incorporated into a double-plate configuration utilizing the basic technique in Figure 1.

[0239] The optical guide 10 in Figure 30 is a nearly flat plane having a rectangular shape in plan view, defined by two short edges joined by two long edges 150. In this example, the length of the short edge 148 of the optical guide 10 is 150 mm and the length of the long edge 150 of the optical guide 10 is 210 mm, but it will be understood that these dimensions may differ in other examples.

[0240] The optical guide 10 in Figure 30 comprises a plurality of pocket injection optics 74, as shown in Figure 7. The light source recesses 30 of the pocket injection optics 74 are arranged along the edges 154, 156 of the optical guide 10. In the example of Figure 30, the optical guide 10 comprises six light source recesses 30 along each short edge 154 of the optical guide and ten light source recesses 30 along each long edge 156 of the optical guide 10. Thus, in this example, the optical guide 10 comprises 32 light source recesses 30 and 32 associated light sources 12 (i.e., 32 pocket injection optics 74) that are placed within the light source recesses 30 when in use. In other examples, it will be understood that the optical guide 10 may have more or fewer pocket injection optics 74.

[0241] Similar to the arrangement in Figure 7, each pocket injection optical system 74 is located in the thick section 46 of the optical guide 10. The tapered section 50 of the optical guide 10 connects the thick section 46 to the thin section 48 of the optical guide 10. In this example, the thin section 48 of the optical guide 10 defines the central region of the optical guide 10, which has a rectangular shape in plan view. The thin section 48 defines the active region or zone 134 of the optical guide 10, in which a touch to the optical guide 10 can be detected when the optical guide 10 is incorporated into a suitable touch detection arrangement, such as a double-plate arrangement similar to that in Figure 1.

[0242] Figures 31a-d show the uniformity of light within a rectangular optical guide 10 having a similar arrangement to that in Figure 30. Specifically, Figure 31a shows the optical guide 10 of Figure 30 with 32 pocket injection optics 74 (not visible in Figure 31a), Figure 31b shows the optical guide 10 similar to that in Figure 30 but with 26 pocket injection optics 74, and Figure 31c shows the optical guide 10 similar to that in Figure 30 but with 20 pocket injection optics 74. Similar to Figures 29a-c, the bright and dark areas of the optical guide 10 in Figures 31a-c show the intensity distribution of light within the optical guide 10, with bright areas indicating high intensity and dark areas indicating low intensity.

[0243] Figure 31d shows the uniformity of optical power density along the central axis (particularly the x-axis as shown in Figure 30) for each optical guide in Figures 31a-c. Lines 158 and 160 represent the upper and lower limits for the optical power density to fall within a range of plus or minus 10%. In Figure 31d, curve 159 represents the optical guide arrangement in Figure 31a, curve 161 represents the optical guide arrangement in Figure 31b, and curve 163 represents the optical guide arrangement in Figure 31c. With this in mind, Figure 31d shows that the arrangements in Figures 31a-c each provide a + / -10% optical power density uniformity within the central region of the optical guide 10.

[0244] Herein, the concept of an optically inert zone is described in more detail. An optically inert zone can be created by using a light-absorbing element, layer, or coating 58 that can be applied to the optical guide 10. The light-absorbing layer or element 58 can be used to isolate individual optical shapes within one zone of the optical guide 10. In addition to or alternatively to avoiding undesirable light leakage from the optical guide 10, a light-absorbing layer or element 58 may be used to prevent light from one zone of the optical guide 10 from interfering with light from another zone of the optical guide 10. Generally, a layer or coating 58 provided on one or more areas of the first surface 23 of the optical guide 10, the second surface 25 of the optical guide 10, or both, can be used to suppress internal reflection in those areas of the relevant surfaces 23, 25 and to provide optical isolation between one part of the top plate 10 and another part of the top plate 10.

[0245] Referring to Figure 32, an optical guide 10 is shown having two optically active zones 162 separated by an optically inactive zone 164. In the optical guide 10 of Figure 32, a first trench injection optical system 52a is used to couple light to a first active region 162a, and a second trench injection optical system 52b is used to couple light to a second active region 162b. The first active region 162a defines a wedge shape with upward and downward inclined portions 166. The second active region 162b defines a slider shape. It should be understood that in other examples, the optical guide 10 may incorporate more or fewer active regions 162, and the active regions 162 may define other shapes such as a dial. Furthermore, the active regions 162 of the optical guide 10 can also be illuminated using light injection shapes, such as the shapes of other trench injection optical systems 52 or pocket injection optical systems 74. Furthermore, different active regions 162 of the light guide 10 can be illuminated using light sources 12 with different characteristics.

[0246] To minimize losses, light is injected into the first active region 162a within a narrow vertical angular range. However, after passing through the wedge shape of the first active region 162a, the angular range of light injected from the first trench injection optics 52a may broaden. In an optical guide 10 without an inactive region 164, as shown in Figure 32, if light from the first trench injection optics 52a proceeds to the second active region 162b and passes through the slider shape of the second active region 162b, the angular range of the injected light broadens further, and some rays may fall below the critical angular limit at the upper surface 23 or lower surface 25 of the optical guide 10 (i.e., outside the range of angles at which total internal reflection occurs at either of these surfaces 23, 25) and be lost from the optical guide 10. As shown in Figure 32, when the light absorption strip 168 is added below the light guide 10 and between the first active region 162a and the second active region 162b, an inactive region 164 is created that separates the first active region 162a and the second active region 162b.

[0247] Referring to Figure 33, in another example of the optical guide 10, a single absorbing inactive region 170 is used to separate multiple active regions 172. An absorbing mask layer 174 having multiple openings is provided on the upper surface 23 of the optical guide 10, defining the multiple active regions 172 of the optical guide 10. Specifically, the touch-detectable active regions 172 of the optical guide 10 are defined by the openings 176 of the absorbing mask layer 174.

[0248] The mask layer 174 may consist of, for example, black paint, or other suitable opaque paint or material. In some examples, the mask layer 174 may be formed by overmolding or the use of IML. As mentioned above, if the device is configured to operate in infrared light, the mask layer 174 may be opaque to “operation” light but transparent to other light such as visible light.

[0249] In the inactive region, various light absorption methods can be used to control or prevent these optical losses, i.e., the loss of light injected from the optical guide 10. Table 1 below summarizes the advantages and disadvantages of three known light absorption methods (use of paint, two-shot molding, and IML). Table 1 shows various absorption methods for zone separation.

[0250] [Table 1]

[0251] This section describes an example of using zone isolation.

[0252] Figures 34a and 34b show an example of end-zone separation of a symmetrical optical guide 10, in which an absorption coating 178 is provided on part or all of the perimeter of the top plate 10. The first trench injection optical system 52a is positioned toward or near the first end 180 of the optical guide 10, and the second trench injection optical system 52b is positioned at the second end 182 on the opposite side of the optical guide 10.

[0253] In the arrangement of FIG. 34a, an absorber is provided on the end face of the optical waveguide 10 to prevent light from leaking out of the optical waveguide 10 through the end face. In this example, by providing the absorber 178 on the second end face 184 of the second end portion 182 of the optical waveguide 10, the light injected into the optical waveguide 10 from the first injection optical system 52a at the first end portion 180 of the optical waveguide 10 is absorbed, and leakage of the light from the optical waveguide 10 through the second end face 184 is prevented. In some examples, by providing the absorber 178 on the first end face 186 of the first end portion 180 of the optical waveguide 10, it is possible to prevent light from leaking from the optical waveguide 10 through the first end face 186, particularly light from the second trench injection optical system 52b.

[0254] In the arrangement of FIG. 34b, the absorber 178 is provided along a part of the end wall of the optical waveguide 10 to prevent light from leaking from the optical waveguide 10 through the end wall. In this example, by providing the absorber 178 on the upper surface 23 of the optical waveguide 10 along the second end wall portion 188 of the second end portion 182 of the optical waveguide 10, the light injected into the optical waveguide 10 from the first injection optical system 52a is absorbed, and leakage of the light from the optical waveguide 10 through the second end wall portion 188 is prevented, and the light is prevented from continuing to travel within the optical waveguide 10. In some examples, by providing the absorber 178 on the first end wall portion 190 of the first end portion 180 of the optical waveguide 10, light leaking from the optical waveguide 10 through the first end wall portion 190, particularly light from the second trench injection optical system 52b, is prevented, and the light is prevented from continuing to travel continuously within the optical waveguide 10. In the arrangement of FIG. 34b, the absorber 178 is provided on the upper surface 23 of the optical waveguide 10, but it should be noted that in some examples, the absorber 178 may be additionally or alternatively provided on the lower surface 25 of the optical waveguide 10.

[0255] In some examples, the absorber 178 may be provided on the end face and the end wall portion as needed.

[0256] In this way, the light traveling from one end to the other end of the optical waveguide 10 is absorbed by the end face and / or the end wall, and leakage of this light from the optical waveguide 10 as stray light is prevented.

[0257] As shown in Figure 35a, light from the first trench injection optical system 52a passes through the optical guide 10 and may be reflected upward by total internal reflection at the input wall (i.e., optical coupling wall 36) of the second trench injection optical system 52b. Such light reflected at the optical coupling wall 36 of the second trench injection optical system may leak out of the optical guide 10 as stray light through the upper surface 23 of the optical guide 10. Figure 35b shows an optical guide 10 in which an absorber 178 is provided on the upper surface 23 of the optical guide 10 to absorb and block the leakage of stray light reflected from the optical coupling surface 36. For this purpose, the absorber 178 extends above and over the entire second injection optical system 52b and its optical coupling wall 36. Note that in some examples, for this purpose, the absorber 178 may be provided additionally or alternatively on the lower surface 25 of the optical guide. For example, an absorber 178 provided on the lower surface 25 of the optical guide 10 in front of the second trench injection optical system 52b (i.e., in the direction away from the second end 182 of the optical guide 10 toward the center of the optical guide) can absorb light from the first injection optical system 52a before it reaches the second trench injection optical system 52b. The same applies to an absorber 178 extending in front of the second trench injection optical system 52b on the upper surface 23 of the optical guide 10.

[0258] As mentioned above, the role of absorbers is more complex, and different properties may be desirable at different wavelengths. In some cases, the absorber described above (for example, when separating the active zone) may absorb at the operating wavelength and transmit at other wavelengths. This allows a device configured for infrared detection to use a "masking" area to separate the visible active area. For example, a display placed behind a touchscreen can be seen through these separators.

[0259] In some examples, absorbers are used to aesthetically mask the subsurface optics and components of the optical guide 10, improving the aesthetics of the arrangement or simplifying the appearance of the device to the user. In this regard, it is useful to add an opaque tint to the optical guide 10 that absorbs the entire visible wavelength and transmits the entire near-infrared (NIR) wavelength used by the light source 12 (e.g., LED light source 12). This is the opposite arrangement to the configuration described above, where it is opaque at the operating wavelength but not at the visible wavelength. Such an opaque tint can be used, for example, to hide the trench injection optics 52, the pocket injection optics 74, or other components below the optical guide 10 from the user's view, while NIR light from the light source 12 can propagate through the optical guide 10 unaffected and unabsorbed.

[0260] As already mentioned, the optical guide 10 described above can be incorporated into a three-layer optical stack as shown in Figure 1 to constitute a touch-sensing device 8, and this three-layer optical stack can be placed above the display to form a touch-sensing screen device 8.

[0261] In this configuration, the upper layer 10 and lower layer 18 of the laminate are sometimes called the transmission layer (Tx) and the receiving layer (Rx), respectively. The upper layer 10 and lower layer 18 are separated by an intermediate layer 14, which may consist of air or an optical material (called cladding) with a lower refractive index than the upper layer 10 and lower layer 18. If the intermediate layer 14 consists of an optical material, the optical material defines a light-transmitting material layer.

[0262] The trench injection optics 52 and pocket injection optics 74 structures, as already described, can be prototyped using a combination of standard acrylic machining and polishing or vacuum casting techniques, suitable for small-scale production. However, using trench or pocket injection optics 52, 74 in the upper layer (transparent layer) 10 of such systems allows for new construction methods that enable medium to large-scale production. For example, using injection molding technology, it is possible to create laminated structures that combine some or all of the optical elements and functions, such as light injection, active and inactive regions, light detection, decorative effects, and display elements. This offers significant advantages, including a minimal form factor, reduced part count, ease of assembly, improved transparency, aesthetics, and ultimately, reduced overall manufacturing and assembly costs. All of these can be designed to use surface-mount electronic components, thereby minimizing the form factor and simplifying assembly.

[0263] As already mentioned, the optical guide 10 can employ various methods to absorb unwanted light, for example, to prevent light from leaking from the roof 34 of the trench or pocket injection optical cavities 52, 74 (see, for example, Figures 10 and 19), or to prevent light from moving from one active region to another (see, for example, Figures 32-35). Such methods using masking techniques make it possible to isolate a region of the optical guide 10, particularly a region of the first surface 23 of the optical guide 10, from other optical activity within the optical guide 10.

[0264] For example, by using a paint with an appropriate absorption spectrum that matches the light source 12, light hitting various surfaces and areas of the light guide 10 can be blocked. However, using paint for this purpose requires a secondary process. The placement of the paint in this secondary process is not always precisely controlled, and in mass production, the use of paint is not cost-effective.

[0265] In two-shot molding or in-mold labeling (IML) / in-mold decoration (IMD) processes, absorbent ink can be placed in the mold as a thin second layer, both of which are attractive alternatives to the methods described above. These manufacturing methods allow for the creation of areas on the touch surface (i.e., the top surface of the top plate or light guide) into which an absorbent mask can be incorporated, thereby achieving (a) concealing components or functions below the top plate 10 from view, (b) optically separating one area from another, (c) providing a decorative effect, or a combination of these effects (a) to (c). Once the molding process is set up, this manufacturing method provides a method for mass production of the top layer (or transparent layer) 10 with precise and effective stray light control.

[0266] IML has a significant advantage (compared to two-shot molding) in that it can achieve attractive decorative effects that make surfaces appear as if they were made of various materials (fabric, carbon fiber, leather, etc.). The LEDs 12 typically used in trench and pocket injection optics 52, 74 emit light in the near-infrared (NIR) region of the spectrum. The inks used in IML can be selected to absorb light across the entire visible spectrum (400-800 nm) and can be used to produce decorative effects. The same inks are selected so as not to absorb NIR light from the LEDs 12 and not to interfere with the touch detection process.

[0267] The embodiments described in detail here generally describe the use of acrylic (e.g., poly(methyl methacrylate) or PMMA) sheets, but it should be noted that they can also be used for other types of three-layer systems. For example, a glass layer can be used instead of an acrylic layer. However, the manufacturing techniques described here are particularly applicable to the acrylic upper and lower layers.

[0268] Table 2 shows a comparison of absorption mask manufacturing processes using two-shot molding or IML / IMD. [Table 2]

[0269] Regarding the overall wall cross-sectional thickness range in Table 2, please note that these values ​​represent what is considered a suitable method for standard mass production.

[0270] Referring again to Figures 8a and 8b, replacing the intermediate air layer 14 in the three-layer system, which includes the upper and lower layers of acrylic, with a layer of material with a higher refractive index reduces the critical ray angle at the boundary (i.e., the angle between the ray and the surface boundary decreases from approximately 48° to 26°). Therefore, when using an intermediate layer with a higher refractive index instead of the intermediate air layer, the angular range within the optical guide 10 needs to be more restricted in order to ensure that virtually all light is totally reflected at the boundary.

[0271] However, using a cladding layer in a three-layer laminate has the advantage of reducing the overall thickness of the laminate compared to using a 1 mm air gap. To achieve this advantage, a low refractive index material with a refractive index as close as possible to that of air is selected as the cladding material, while maintaining as wide a range as possible of the angular range in which light undergoes total internal reflection at the boundary between the upper and lower layers and the cladding. In some examples, this cladding layer can take the form of an intermediate FEP layer, but other materials can also be used.

[0272] Using a low refractive index intermediate layer instead of an air gap reduces Fresnel reflection at the boundary between the upper (transmitting) layer and the intermediate layer, and at the boundary between the lower (receiving) layer 18 and the intermediate layer 14. This improves the overall transmittance and transparency of the laminate. Furthermore, using a low refractive index intermediate layer instead of an air gap in the laminate structure improves the robustness of the manufactured assembly.

[0273] A drawback of replacing the air gap with the low refractive index intermediate layer 14 is that the mean ray reflection angle becomes shallower, resulting in a decrease in the intensity of the evanescent field. Furthermore, in laminates using the low refractive index intermediate layer 14 instead of air, the angular range of total internal reflection must be narrowed, which reduces the optical coupling efficiency.

[0274] This section describes an example of a manufacturing scheme that combines a low refractive index interlayer with two-shot molding or in-mold labeling.

[0275] Figure 36 shows a touch-sensing device formed from the composite 192. The composite 192 comprises an upper layer (transmitting layer) 10 in the form of a light-transmitting sheet that defines the touch surface 23 of the device. The composite 192 further comprises a lower layer (receiving layer) 18 in the form of an additional light-transmitting sheet, and an intermediate layer 14 defined by an air gap between the upper layer 10 and the lower layer 18. The upper layer 10 comprises a trench injection optical system 52 (only one of which is shown in Figure 36) which includes an array of light sources 12 positioned within the light source recess 30 of the trench injection optical system 52. It should be understood that the arrangement in Figure 36 can incorporate one or more pocket injection optical systems 74 in addition to, or instead of, the trench injection optical system 52.

[0276] In this example, the light source 12 is an LED operating in the near-infrared (NIR) region of the spectrum. The device comprises a single printed circuit board (PCB) 54 to which the light source 12 is mounted, with an upper layer 10 and a lower layer 18 held on both sides of the PCB 54 using a mechanical frame or holder 194. An ethylene vinyl acetate (EVA) foam spacer 196 is inserted between the upper layer 10 and the lower layer 18 to create or provide an air gap 14, keeping the upper layer 10 and the lower layer 18 separated from each other. In this way, the lower layer or base plate 18 is mounted relative to the upper layer or top plate 10, and when an external object touches the first surface 23 of the top plate 10, light is coupled to the base plate 10 from the second surface 25 of the top plate 10 through the first surface or top surface of the base plate 10. Another EVA spacer 198 is inserted between the lower layer 18 and the display 200, which forms part of the composite 192, to form an air gap 202 and keep the lower layer 18 and the display 200 separated from each other.

[0277] By adding acetate film to the contact points of the upper or lower layers (i.e., the contact areas between the upper layer 10 and other components, and between the lower layer 18 and other components), the upper layer 10 and lower layer 18 are "wetted" to prevent the contained light from leaking out. The upper layer 10 is injection molded using an IML insert in the tool, allowing for the addition of borders, graphics, or texture effects to a portion of the upper surface 23 of the upper layer 10 without completely covering the display 200 below it. Furthermore, a thin layer 204 of material 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 on the underside of the IML film 203. Thus, the LED 12 below layer 204 is hidden from the user's view, but the NIR light emitted by the LED 12 is totally reflected from the upper surface 23 of the upper layer 10. Similar to the arrangement in Figure 3, the separate opaque layer portions 206 (i.e., light-absorbing elements) provided on the upper surface 32 and back surface 38 of the light source recess 30 between the light source 12 and the first surface of the light guide 10 define the light source aperture 56 in the arrangement in Figure 36 and limit the angular range of light emitted by the LED 12 coupled to the upper layer of the light guide 10.

[0278] Alternative mask configurations are also possible. In one alternative mask configuration (not shown), the opaque near-infrared absorbing coating 206, which is provided in the recess 30 above the light source in the configuration of Figure 36, can be omitted, and instead, the light source aperture 56 can be defined by the upper surface IML film configuration. Specifically, a portion of the upper surface IML film configuration located above the recess 30 absorbs the near-infrared region of the spectrum to mimic the absorbing coating 206 in the configuration of Figure 36. In this case, the upper surface IML film configuration still retains a decorative effect of absorbing visible light, as in the configuration of Figure 36.

[0279] If necessary, a sensor in the form of a photodetector 20 is placed on the edge of the lower layer 18 and detects light coupled from the upper layer 10 to the lower layer 18 in response to a touch on the upper surface 23 of the upper layer 10.

[0280] Figure 37 shows another composite device 192 using a single PCB 54 (i.e., similar to Figure 36). The device in Figure 37 includes an additional IML film 208 that provides a similar function to the layer defining the light source aperture 56 in Figure 36. Thus, the arrangement in Figure 37 does not include the opaque layer portion 206 provided on the top surface 32 and back surface 38 of the light source recess 30, with the additional IML film 208 replacing this element. In particular, the additional IML film 208 has an opaque layer 210, which is used to limit the angular range of light coupled from the LED 12 to the upper layer 10. This provides a single stacked upper layer optical structure, which simplifies assembly.

[0281] Similar to the explanation for Figure 36, alternative mask configurations (not shown) can also be used here. For example, one possible alternative mask configuration is to define the light source aperture 56 using a different top IML film configuration configured to absorb the near-infrared region in a suitable area above the light source 12, omitting the additional IML film 208. In this case, the top IML film configuration can still retain a decorative effect that absorbs visible light, similar to the configuration in Figure 36.

[0282] Figure 38 shows a touch-sensing device formed by a laminate 212. The laminate 212 comprises an upper layer 10 defining a light-transmitting sheet, a lower layer 18 defining a further light-transmitting sheet, and an intermediate optical layer 14 taking the form of a low-refractive-index intermediate layer between the upper layer 10 and the lower layer 18. In this example, the low-refractive-index intermediate layer 14 is a single low-refractive-index optical adhesive layer that provides optical coupling between the light-transmitting sheets 10 and 18. In other examples, this intermediate layer may take a different suitable form. For example, in some examples, the intermediate layer may be formed by a stack of sublayers.

[0283] Figure 43 shows an example of an intermediate layer 14a formed from a stack of sublayers. The intermediate layer 14a includes upper and lower optically transparent adhesive film layers 213 that engage and bond to the upper layer 10 and the lower layer 18, respectively. The intermediate layer 14a further includes two polycarbonate layers 215 and a central low refractive index adhesive layer 217. In the example in Figure 43, the upper and lower adhesive layers 213 are 0.25 mm thick, the polycarbonate layer 215 is 0.1 mm thick, and the central low refractive index adhesive layer 217 is approximately 5 μm thick. In other examples, the materials and morphologies of the sublayers may differ, and in particular, the number and thickness of the sublayers in the stack may differ.

[0284] Returning to Figure 38, the laminate 212 further comprises a display 200 positioned beneath the lower layer 18, and an additional low refractive index layer 214 provided between the lower layer 18 and the display 200. Similar to the arrangements in Figures 36 and 37, the device in Figure 38 includes a single PCB 54.

[0285] In contrast to the arrangements in Figures 36 and 37, it will be understood that the air layers between the upper layer 10 and the lower layer 18, and between the lower layer 18 and the display 200, are replaced by low refractive index layers 14 and 214. The low refractive index layers 14 and 214 are optically coupled to the upper layer 10 and the lower layer 18 via optical coupling layers. This makes the manufacturing process more complex, but provides a single stacked optical component, making assembly even easier.

[0286] Similar to the arrangement in Figure 36, separate opaque layer portions 206 positioned at the top and rear of the light source recess 30 define the light source aperture 56 in the arrangement in Figure 38 and limit the angular range of light emitted by the LED 12 coupled to the upper light guide 10. As described above, in the embodiment, this opaque layer portion 206 is opaque only in the “operating” near-infrared range and may actually be transparent in part or all of the visible spectrum. Also, similar to the arrangement in Figure 36, a thin layer 204 of material is printed on the underside of the IML film 203, which is transparent to light in the near-infrared region of the spectrum but absorbs light in the visible region of the spectrum. Layer 204 is formed in the lamination process. The device in Figure 38 further includes an absorption structure 218 positioned to block light that is not desired to be totally reflected and continue propagating within the light guide 10.

[0287] It will be understood that the upper layer 10 in the arrangement of Figure 38 has a tapered wedge portion 50 between a thick portion 46 of the optical guide 10 containing the trench injection optical system 52 and a thin portion 48 of the optical guide 10 that defines the active region of the optical guide 10 where touch can be detected.

[0288] Figure 39 shows another touch-sensing device formed using a laminate 212 (similar to that in Figure 38). Many features of the device in Figure 39 are the same as those of the arrangement in Figure 38, and will not be described again for brevity. In contrast to the arrangement in Figure 38, the arrangement in Figure 39 includes an additional IML film 220 positioned on the underside of the upper layer 10 so as to extend across the back surface 38 and top surface 32 of the light source recess 30, which provides a similar function to the separate opaque layer portion 206 that defines the light source aperture 56 in Figure 38. The additional IML film 220 functions to control the angular range of light from the LED 12 coupled to the upper layer 10. Note that, as with the arrangement in Figure 36, the arrangement in Figure 39 has a thin layer 204 of material printed on the underside of the IML film 203, which is transparent to light in the near-infrared region of the spectrum but absorbs light in the visible region of the spectrum. Layer 204 is formed during the lamination molding process.

[0289] It should be noted that alternative mask configurations are also possible. In one such alternative mask configuration (not shown), the additional IML 220 above the LED 12 can be omitted, and a different top IML film configuration can be used that is configured to absorb the near-infrared region in a suitable area above the light source 12 and define the light source aperture 56. In this case, the top IML film configuration can retain the decorative effect of absorbing visible light, as before.

[0290] From the above explanation, it can be seen that injection molding technology can be used to combine the manufacturing elements of light injection, light distribution, and light separation, and these can be combined into a laminated structure. The light-absorbing layer can be replaced with an in-mold label (IML), and the air gap between the upper and lower layers can be replaced with a low refractive index layer such as FEP.

[0291] Those skilled in the art will understand that the present invention can be modified to take many forms other than those described herein without departing from the scope of the appended claims.

Claims

1. Top plate and base plate and Equipped with, The top plate comprises one or more associated light sources, Light from one or more of the aforementioned light sources propagates through the top plate by total internal reflection. The base plate comprises one or more detectors associated with detecting light propagated within the base plate, The top plate and the base plate are configured such that when an external object touches the first surface of the top plate, light is transmitted from the second surface of the top plate through the first surface of the base plate to the base plate. Each of the one or more light sources is positioned in a recess for the light source within the top plate, the recess having one or more refractive input surfaces, and light from the light source is coupled to the body of the top plate via the one or more refractive input surfaces. Touch sensor.

2. The touch sensing device according to claim 1, wherein, in the case of one or more light sources, the recess has a central refractive input surface and two side refractive surfaces arranged symmetrically with respect to the central refractive input surface and adjacent to the central refractive input surface.

3. The touch sensing device according to claim 2, wherein the curvature of the central refraction input surface is different from the curvature of the side refraction surface.

4. The touch sensing device according to claim 3, wherein the central refraction input surface has a conical curvature.

5. The touch sensing device according to claim 4, wherein the central refraction input surface has an elliptical curvature.

6. The touch sensing device according to any one of claims 1 to 5, wherein the refractive input surface or the wall of each refractive input surface forms an angle with respect to the plane of the top plate, so that the refractive input surface and the second surface of the top plate form an obtuse angle within the top plate.

7. The attachment of the light source to the refractive input surface or the wall of each refractive input surface increases the intensity of the evanescent field and refracts the light so as to confine it within the top plate by total internal reflection, according to any one of claims 1 to 6.

8. The touch sensing device according to any one of claims 1 to 7, wherein the refractive input surface or the walls of each refractive input surface are lensified.

9. The touch sensing device according to any one of claims 1 to 8, wherein the light source or each light source is mounted at an angle to the plane of the top plate such that the light emitted from the light source is mainly directed at an angle to the first surface.

10. The touch sensing device according to any one of claims 6 to 9, wherein each light source is mounted such that the light emitted from each of the light sources is mainly directed obliquely to at least one refractive input surface.

11. The touch sensing device according to any one of claims 1 to 10, wherein the top plate further comprises a narrow portion in which the distance between the first surface and the second surface is substantially constant, but smaller than the distance between the first surface and the second surface in the recess.

12. The touch sensing device according to claim 11, wherein the top plate further comprises a tapered portion that narrows the distance between the first surface and the second surface of the top plate, and the tapered portion is located between the recess and the narrow portion.

13. The touch sensing device according to claim 12, wherein the tapered portion is linearly tapered.

14. The touch sensing device according to claim 12, wherein the tapered portion is nonlinearly tapered.

15. The touch sensing device according to any one of claims 1 to 14, wherein an air gap exists between the top plate and the bottom plate.

16. The touch sensing device according to any one of claims 1 to 14, wherein a light-transmitting material layer is present between the top plate and the bottom plate.

17. The touch sensing device according to any one of claims 1 to 16, wherein the region of the first surface is masked to prevent total internal reflection of light from each light source in the recess.

18. The touch sensing device according to claim 17, wherein the masking is provided on a part of the first surface located above the recess and extending beyond the recess, thereby limiting the incident angle range of light reflected from the plurality of light sources onto the first surface.

19. The touch sensing device according to claim 17 or 18, wherein the masking is provided on or by a light-absorbing layer provided on the first surface.

20. The touch sensing device according to claim 17 or 18, wherein the touch sensing device comprises a plurality of light sources, and the masking extends over two or more of the plurality of light sources.

21. The touch sensing device according to claim 20, wherein the masking defines the active area of ​​the top plate, and the plurality of light sources illuminate the active area of ​​the top plate.

22. The touch sensing device according to claim 21, wherein the plurality of light sources are arranged on the outer periphery of the active area.

23. The touch sensing device according to claim 22, wherein the outer periphery of the active area is rectangular.

24. The touch sensing device according to claim 22, wherein the outer periphery of the active area is elliptical.

25. The touch sensing device according to any one of claims 21 to 24, wherein the first surface of the top plate in the active region is not planar.

26. The touch sensing device according to any one of claims 21 to 25, wherein the plurality of light sources are arranged at intervals to form a substantially uniform light distribution in the active area of ​​the top plate.

27. The touch sensing device according to any one of claims 1 to 26, wherein the regions of each recess between the light source and the first surface are masked.

28. The touch sensing device according to claim 27, wherein the masking is provided by a light-absorbing layer provided on or on the surface of the recess.

29. The touch sensing device according to claim 27 or 28, wherein the masking is performed by a light-absorbing element attached to the light source.

30. The touch sensing device according to any one of claims 27 to 29, wherein the masking in the region of the recess defines an opening for emitting light from the light source to the top plate.

31. The touch sensing device according to any one of claims 1 to 30, wherein each of the one or more light sources is a light-emitting diode.

32. The touch sensing device according to claim 31, wherein each of the one or more light-emitting diodes emits near-infrared light.

33. The touch sensing device according to any one of claims 1 to 32, wherein one or more refractive input surfaces are configured to limit the vertical angular range of light propagating from the light source within the top plate.

34. The touch sensing device according to any one of claims 1 to 33, wherein the one or more refractive input surfaces are configured to expand the horizontal angular range of light incident on the one or more refractive input surfaces.

35. The touch sensing device according to any one of claims 1 to 34, wherein the light-emitting region of the light source is positioned at a predetermined distance from one or more refractive input surfaces so as to limit the vertical angular range of light rays propagating from the light source within the top plate.

36. The touch sensing device according to any one of claims 1 to 35, wherein the vertical angular range of the light rays propagating from the light source within the top plate is limited such that substantially all of the light coupled from the light source to the top plate is confined within the top plate by total internal reflection.

37. The touch sensing device according to any one of claims 1 to 36, wherein one or more of the following are configured to limit the vertical angular range of light propagating from the light source through the top plate: the angle of the refractive input surface or each refractive input surface with respect to the refractive input surface or each refractive input surface; the mounting of the light source to the refractive input surface or each refractive input surface; and the curvature of the refractive input surface or each refractive input surface.

38. The touch sensing device according to any one of claims 1 to 37, wherein the recess or each recess is defined on the second surface of the top plate.

39. The top plate is associated with a plurality of secondary light sources, Light from the secondary light source propagates through the top plate by total internal reflection. The secondary light source is positioned in a secondary recess that extends linearly within the second surface of the top plate, and light from the secondary light source is coupled to the top plate via the wall of the secondary recess. The touch sensing device according to any one of claims 1 to 38, wherein the secondary light source forms a linear array within the linearly extending secondary recess.

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