CN111542772B

CN111542772B - Light emitting device with a film-based light guide and an additional reflective surface

Info

Publication number: CN111542772B
Application number: CN201880084689.7A
Authority: CN
Inventors: A·尼科尔; Z·科尔曼
Original assignee: Flex Lighting ll LLC
Current assignee: Azumo Inc
Priority date: 2017-11-03
Filing date: 2018-11-02
Publication date: 2022-10-28
Anticipated expiration: 2038-11-02
Also published as: WO2019090139A1; CN111542772A

Abstract

The light emitting device includes a light guide formed from a film having an array of coupling lightguides in the form of strips extending from a lightguide region of the film, the coupling lightguides being folded and stacked, and a light source positioned to emit light into an edge of the stacked coupling lightguides to propagate into a light mixing region and then into a light emitting region. The light-mixing region includes a plurality of reflective surfaces that reflect a portion of the light from the coupling lightguides toward one or more lateral edges of the film before being emitted out of the film from the light-emitting region. The plurality of reflective surfaces may be linear, arrayed, or of a light transmissive material printed on the surface of the film, and may improve the uniformity of light emitted from the light emitting region.

Description

Light emitting device with a film-based light guide and an additional reflective surface

Technical Field

The subject matter disclosed herein relates generally to light guides, films, and light emitting devices, such as, but not limited to, light fixtures, backlights, frontlights, illuminated signs, passive and active displays, and components and methods of making the same.

Background

The market demands a light emitting device equipped with a very thin form factor that can produce a specific angle light output profile. Traditionally, to reduce the thickness of displays and backlights, side-lit designs using rigid light guides have been used to receive light from the edges and direct the light out of a larger area surface. These types of light emitting devices are typically housed in relatively thick rigid frames that do not allow flexibility in parts or equipment and require long lead times for design changes. These devices are still bulky and typically include a thick or large frame or bezel surrounding the device. Thick light guides (typically 2 millimeters (mm) or more) limit design configurations, production methods, and illumination modes. The ability to further reduce the thickness and overall volume of these area light emitting devices has been limited by the ability to couple sufficient luminous flux into thinner light guides. In some designs, achieving a high degree of uniformity of the light-emitting area has been problematic in some configurations due to the introduction of artifacts from the array of coupled light guides and the different desired form factors including a wider light-emitting area than the light-mixing area.

Content providing method and apparatus

In one embodiment, a light emitting device includes a light guide formed from a film having an array of coupling light guide strips extending from a light guide region of the film, the coupling light guides being folded and stacked, and a light source positioned to emit light into an edge of the stacked coupling light guides to propagate the light to a mixing region of the coupling light guides and then into a light emission region.

In one embodiment, the light-mixing region includes a plurality of linear reflective surfaces between the lateral edges of the film, wherein light emitted from the light source propagates within the array of coupling lightguides by total internal reflection to the light-mixing region, mixes within the light-mixing region upon exiting the array of coupling lightguides, reflects from one or more of the plurality of linear reflective surfaces toward one or more lateral edges of the film, and exits the film in the light-emitting region. In one embodiment, the linear reflective surfaces are parallel stripes of light transmissive material disposed on the surface of the film. In another embodiment, the plurality of linear reflective surfaces have an average length in a direction perpendicular to the array direction of the array of coupling lightguides and perpendicular to the film thickness direction of the light mixing region, the plurality of linear reflective surfaces have an average width in a direction parallel to the array direction of the array of coupling lightguides and perpendicular to the thickness direction of the film of the light mixing region, and the average length divided by the average width is greater than 5. In another embodiment, an average area of one surface of the plurality of opposing surfaces occupied by the plurality of linear reflecting surfaces is less than 40% of an area of the surface defined by the plurality of linear reflecting surfaces. In one embodiment, the plurality of linear reflective surfaces are positioned on a core layer of the film, a total cross-sectional area of the plurality of linear reflective surfaces in a plane that includes a thickness direction of the film and that is parallel to an array direction of the array of coupling lightguides being less than 40% of a total continuous cross-sectional area of the core layer of the film directly below the plurality of linear reflective surfaces. In one embodiment, the plurality of linear reflective surfaces are oriented lengthwise along a direction perpendicular to an array direction of the array of coupling light guides. In one embodiment, the plurality of linear reflective surfaces reflect less than 20% of light propagating within the light guide out of the light guide in the light mixing region. In one embodiment, the array of coupling light guides has an average pitch in an array direction of the array of coupling light guides and the plurality of linear reflective surfaces has an average pitch in an array direction of the array of coupling light guides, wherein the average pitch of the array of coupling light guides is at least 5 times greater than the average pitch of the plurality of linear reflective surfaces. In one embodiment, the light-mixing region comprises a fold such that a portion of the light-mixing region is positioned behind the light-emitting region in a thickness direction of the film. In one embodiment, at least a part of the plurality of linear reflecting surfaces is located behind the light emitting region in a thickness direction of the thin film. In one embodiment, the light emitting apparatus comprises a reflective spatial light modulator having a front view side optically coupled to the film in the light emitting area of the film, wherein light exiting the film in the light emitting area illuminates the reflective spatial light modulator from the front view side. In one embodiment, the light mixing region comprises a plurality of linear reflective surfaces affixed to a light transmissive material of the thin film; the plurality of linear reflective surfaces extend away from the array of coupling lightguides toward the light emission region, wherein light emitted from the light source propagates within the array of coupling lightguides by total internal reflection to the light mixing region, mixes in the light mixing region upon exiting the coupling lightguides, reflects from one or more of the plurality of linear reflective surfaces toward one or more of the lateral edges of the film, and exits the film in the light emission region. In one embodiment, the plurality of linear reflecting surfaces are oriented such that a portion of the plurality of linear reflecting surfaces has features parallel to a thickness direction of the film. In one embodiment, the array of coupling lightguides has an average width in an array direction of the array of coupling lightguides and the plurality of linear reflective surfaces has an average width in the array direction, wherein the average width of the array of coupling lightguides divided by the average width of the plurality of linear reflective surfaces is greater than 10. In one embodiment, the light mixing region comprises a plurality of reflective surfaces of light transmissive material printed on a surface of the opposing surface of the film; the plurality of reflective surfaces extend away from the array of coupling lightguides toward the light emission region, wherein light emitted from the light source propagates within the array of coupling lightguides by total internal reflection to the light mixing region, mixes in the light mixing region upon exiting the coupling lightguides, reflects from one or more of the plurality of reflective surfaces toward one or more of the lateral edges of the film, and exits the film in the light emission region. In one embodiment, the plurality of reflective surfaces have an average wetting contact angle of less than 20 degrees in a plane that includes a thickness direction of the film and is parallel to an array direction of the array of coupling lightguides.

In one embodiment, the plurality of reflective surfaces are surfaces of a core layer of the film formed by cutting, dicing or scribing in the core layer of the film in the light mixing region. In one embodiment, the plurality of reflective surfaces are injection molded by injection molding the reflective surfaces onto a top surface of an injection molded light guide having an average thickness of less than 0.5 millimeters.

In one embodiment, the film-based light guide includes a light-emitting region of the film that includes a light-mixing region, a light-guiding region, or a light-emitting region having an excess width region in an array direction of the array of coupling lightguides, e.g., the light-emitting region has an excess width region that extends beyond a lateral edge of the light-mixing region in a direction parallel to the array direction of the array of coupling lightguides. In one embodiment, at least one of the light-mixing region, the light-guiding region, and the light-emitting region extends beyond the array of coupling lightguides in the direction of the array of coupling lightguides, and the device includes one or more light-scattering or guiding features (e.g., internal light-guiding edges) that direct light directly toward the excess width region, or that indirectly direct light to appear to emanate from the excess width region, thereby reducing the visibility of the angular shadow region.

Brief description of the drawings

Fig. 1 is a top view of an embodiment of a light emitting device with a light input coupler arranged at one side of a light guide.

Fig. 2 is a perspective view of one embodiment of a light input-coupler with a coupling light guide folded in the-y direction.

Fig. 3 is a top view of an embodiment of a light emitting device with two light input-couplers arranged on the same side of the light guide, wherein the optical axes of the light sources are oriented substantially towards each other.

Fig. 4 is a top view of one embodiment of a light emitting device including three optical input couplers.

Fig. 5 is a cross-sectional side view of an embodiment of a light emitting device comprising a light input coupler and a light guide provided with a reflective optical element near a surface.

FIG. 6 is a perspective view of one embodiment of a light emitting device having a light mixing region surrounding a stack of relative position maintaining elements and coupling lightguides.

FIG. 7 is a top view of one embodiment of a coupling light guide in three different positions.

FIG. 8 is a top view of one embodiment of a light input-coupler comprising a film-based light guide with interleaved coupling light guides.

FIG. 9 is a top view of one embodiment of a light emitting device including coupling lightguides each having a plurality of first reflective surface edges and a plurality of second reflective surface edges.

Fig. 10 is an enlarged perspective view of the input end of the coupling light guide of fig. 9.

FIG. 11 is a top view of one embodiment of a film-based light guide including an array of tapered coupling light guides.

FIG. 12 is a top perspective view of a light emitting device of one embodiment that includes the film-based light guide of FIG. 11 and a light source.

FIG. 13 is a top view of one embodiment of a film-based light guide including an array of directional coupling light guides having tapered light collimating lateral edges adjacent to an input surface and light turning edges between the light input surface and a light mixing region of the film-based light guide.

FIG. 14 is a cross-sectional side view of one embodiment of a spatial display including a front light.

FIG. 15 is a cross-sectional side view of one embodiment of a light emitting display that includes a light guide that also serves as the top substrate for a reflective spatial light modulator.

FIG. 16 is a perspective view of one embodiment of a light emitting device that includes a thin film based light guide that also serves as the top substrate of a reflective spatial light modulator with its light source disposed on a circuit board that is physically connected to a flexible connector.

FIG. 17 is a top view of one embodiment of a film-based light guide including an array of coupling light guides with varying separation distances between adjacent coupling light guides.

FIG. 18 is a perspective view of one embodiment of a light input-coupler and light guide including relative position-retaining elements disposed near a linear fold region.

Fig. 19 is a perspective view of one embodiment of a Relative Position Maintaining Element (RPME) including a ridge and truncated angled teeth.

FIG. 20 is a top view of one embodiment of a film-based light guide including a light mixing region extending past a light emission region.

FIG. 21 is a cross-sectional side view of a portion of one embodiment of a spatial display illuminated by a front light that includes a film-based light guide optically coupled to a reflective spatial light modulator and a scratch-resistant hard coat on a hard coat substrate optically coupled to the film-based light guide.

Figure 22 is a top view of one embodiment of a light emitting device including a light source and a photodetector in two optical input couplers.

FIG. 23 is a top view of one embodiment of a film-based light guide including an array of coupling light guides and a sacrificial coupling light guide including perforated lines.

FIG. 24 is a perspective view of the film-based light guide of FIG. 23, with an array of coupling light guides and a sacrificial coupling light guide folded and stacked.

FIG. 25 is a cross-sectional side view of a portion of one embodiment of a spatial display illuminated by a front light including a color filter adhered to and optically coupled to a color reflective display such that light from the front light directly illuminates the color reflective display.

Fig. 26 is a top view of one embodiment of a light emitting device including a first light input-coupler coupling light into a sub-display light-emitting area of a film-based light guide, and a second light input-coupler and a third light input-coupler coupling light into a main display light-emitting area of the film-based light guide.

Fig. 27 is a top view of one embodiment of a light emitting device including a main display and a sub-display illuminated by the light emitting device of fig. 26.

FIG. 28 is a perspective view of one embodiment of a wrapped light guide comprising a film-based light guide, an array of coupling light guides positioned within a cavity of a light input-coupler housing, and a conformal wrapping material inserted into the cavity.

Fig. 29 is a cross-sectional side view of a portion of one embodiment of a light emitting device including a light source, a light guide, a light input coupler, and a flexible cladding layer disposed around an array of folded, stacked coupled light guides, the cladding layer including alignment guide holes at alignment guide areas and perforations at the alignment guide areas that can be used to remove the cladding layer.

Fig. 30 is a perspective view of one embodiment of a Relative Position Maintaining Element (RPME) including ridges, angled teeth, grooves in the ridge regions between the angled teeth so that the RPME can bend and/or break apart along the grooves.

Fig. 31, 32 and 33 are different perspective views of one embodiment of a relative position maintaining element including a ridge and angled teeth extending from below the ridge.

FIG. 34 is a cross-sectional side view of one embodiment of a light emitting device including low angle light directing features.

FIG. 35 is a cross-sectional side view of one embodiment of a light emitting device including light turning features.

Fig. 36 is a perspective view of one embodiment of a light emitting device including a phase compensation element.

FIG. 37 is a cross-sectional side view of one embodiment of a light emitting device including a light turning feature and a low angle directing feature.

FIG. 38 is a top view of a portion of one embodiment of a light emitting device including an array of coupled light guides and corner shaded regions formed by excess width regions.

FIG. 39 is a cross-sectional side view of one embodiment of a light emitting device including printed light scattering areas to reduce visibility of angular shadow areas.

FIG. 40 is a cross-sectional side view of one embodiment of a light emitting device including light directing features of varying depth to reduce visibility in the area of angular shading.

FIG. 41 is a top view of a portion of one embodiment of a light emitting device having an internal light guiding edge that reduces visibility of an angularly shaded region.

FIG. 42 is a top view of one embodiment of a display including a thin film based light guide having an octagonal light emitting area extending beyond a coupling light guide and an octagonal reflective spatial light modulator.

FIG. 43 is a top view of an embodiment of a display including an array of three sets of coupling lightguides and a light mixing region extending from an octagonal light emitting region positioned above an octagonal reflective spatial light modulator.

FIG. 44 is a perspective view of an embodiment of an optical input-coupler that receives different angular optical outputs from two optical sources.

FIG. 45 is a top view of one embodiment of a light emitting device including two film-based light guides with different angular light output profiles.

FIG. 46 is a top view of one embodiment of a light emitting device including a film-based light guide backlight and a second backlight.

FIG. 47 is a top view of one embodiment of a display including a film-based front light having tapered lateral edges in a light-mixing region.

FIG. 48 is a top view of one embodiment of a light emitting device including a film-based light guide including a plurality of reflective surfaces arrayed in a light mixing region.

Fig. 49 is a cross-sectional view of the light emitting apparatus shown in fig. 48.

FIG. 50 is a cross-sectional view of a thin-film based light guide in a light mixing region of one embodiment of a light emitting device that includes multiple reflective surfaces in the form of printed lines of light transmissive material.

FIG. 51 is a cross-sectional view of a film-based light guide in a light mixing region for one embodiment of a light emitting device that includes multiple reflective surfaces in the form of cutouts in a core layer of the film-based light guide.

FIG. 52 is a perspective view of one embodiment of a light emitting device comprising a film-based light guide and an array of multiple reflective surfaces optically coupled to the film-based light guide.

FIG. 53 is a perspective view of one embodiment of a light emitting device including an array of multiple reflective surfaces optically coupled to a film-based light guide over a portion of a light mixing region that is folded behind the light emitting region of the film-based light guide.

Detailed Description

Features and other details of several embodiments will now be described in more detail. It is to be understood that the specific embodiments described herein are for purposes of illustration and not limitation. The primary features may be used in various embodiments without departing from the scope of any particular embodiment. All parts and percentages are by weight unless otherwise indicated.

Definition of

An "electroluminescent display" is defined herein as a device for displaying information on which legends, messages, images or indicia are formed or made more apparent by an electrically activated source of illumination. These include luminescent cards, transparent films, pictures, printed graphics, fluorescent signs, neon signs, channel letter signs, light box signs, bus stop signs, illuminated advertising signs, EL (electroluminescent) signs, LED signs, edge lit signs, advertising displays, liquid crystal displays, electrophoretic displays, point of purchase displays, direction indicators, luminescent pictures and other information display signs. Electroluminescent displays may be self-illuminating (illuminated), back-illuminating (backlit), front-illuminating (frontlit), edge-illuminating (edge-lit), waveguide-illuminating, or other configurations in which light from a light source is directed through static or dynamic means for creating an image or indicia.

"optical coupling" is defined herein as coupling two or more regions or layers such that the luminance of light from one region to another is not substantially reduced by fresnel interface reflection losses due to differences in refractive index between the regions. "optical coupling" methods include coupling methods in which two regions coupled together have similar refractive indices, or use an optical adhesive having a refractive index substantially close to or between the refractive indices of the regions or layers. Examples of "optical coupling" include, but are not limited to, lamination using an index-matching optical adhesive, coating one region or layer onto another region or layer, or thermal lamination using applied pressure to join two or more layers or regions of substantially similar refractive index. Thermal conduction is another method that can be used to optically couple two regions of material. Forming, modifying, printing, or applying one material on the surface of another material is another example of optically coupling two materials. "optically coupling" also includes forming, adding or removing regions, features or materials of a first refractive index within a volume of material of a second refractive index such that light propagates from the first material to the second material. For example, a white light scattering ink (e.g., titanium dioxide in a methacrylate, vinyl, or polyurethane based adhesive) may be optically coupled to the surface of a polycarbonate or silicone film by ink-jet printing the ink on the surface of the polycarbonate or silicone film. Similarly, a light scattering material, such as titanium dioxide, in a solvent applied to the surface may infiltrate or adhere the light scattering material in close physical contact with the surface of the polycarbonate or silicone film, thereby optically coupling it to the film surface or volume.

"light guide" or "waveguide" refers to a region bounded by: light rays propagating at angles greater than the critical angle will reflect and remain within this region. In the light guide, if the angle (α) satisfies the condition α>sin ^-1 (n ₂ /n ₁ ) The light will be reflected or TIR (total internal reflection), where n1 is the refractive index of the medium inside the light guide and n2 is the refractive index of the medium outside the light guide. Typically, n2 is air with a refractive index n ≈ 1. However, high and low index materials may be used to form the lightguide region. A light guide need not be optically coupled to all of its components to be considered a light guide. Light can enter from any surface (or interface refractive index boundary) of the waveguide region, andand may be totally internally reflected from the same or another refractive index interface boundary. One region may serve as a waveguide or light guide as described herein, as long as the thickness is greater than the wavelength of the light of interest. For example, the light guide may be a 5 micron region or layer of film, or may be a 3 mm sheet comprising a light transmissive polymer.

"touching" and "disposed on …" are generally used to describe two articles adjacent to each other so that the entire article can function as desired. This may mean that additional material may be present between adjacent articles, as long as the object can function as desired.

As used herein, "film" refers to a thin extended region, film or layer of material.

As used herein, "bending" refers to deformation or transformation of a shape, for example, by movement of a first region of an element relative to a second region. Examples of bending include the clothes pole bending or rolling up a paper document to fit into a cylindrical mailbox when heavy clothing is hung on the clothes pole. As used herein, "fold" is one of a bend and refers to the bending or placement of one region of an element over a second region such that the first region covers at least a portion of the second region. One example of folding includes bending a letter and forming a crease to place it in the envelope. The folding does not require that all areas of the elements overlap. The bending or folding may be a change in direction along a first direction of the surface of the object. A fold or bend may or may not have a crease, and the bend or fold may occur in one or more directions or planes (e.g., 90 degrees or 45 degrees). The bending or folding may be transverse, vertical, torsional, or a combination thereof.

Light emitting apparatus

In one embodiment, a light emitting device includes a first light source, a light input-coupler, a light mixing region, and a light guide including a light emitting region having light extraction features. In an embodiment, the first light source has a first light source emitting surface, the light in-coupler comprises an input surface arranged to receive light from the first light source and to transmit the light through the light in-coupler by total internal reflection through the plurality of coupling light guides. In this embodiment, light exiting the coupling lightguide is recombined and mixed in the light mixing region and guided by total internal reflection within the lightguide or lightguide region. Within the lightguide, a portion of the incident light is guided into the light extraction region by the light extraction features to form a state where the angle of the light is less than the critical angle of the lightguide and the guided light exits the lightguide through the lightguide light emission surface.

In a further embodiment, the lightguide is a film with light extraction features below the light emitting device output surface within the film. The film is separated into coupled light guide strips, which are folded such that the coupled light guide strips form a light input coupler having a first input surface formed by a collection of edges of the coupled light guide strips.

In one embodiment, the light emitting device has an optical axis, which for a device having an output profile with one peak is defined herein as the direction of the peak luminous intensity of the light emitted from the light emitting surface or area of the device. For a light output profile having more than one peak and output symmetric about an axis, such as a profile having a "batwing" type, the optical axis of the light emitting device is the axis of symmetry of the light output. In a light emitting device having an angular luminous intensity light output profile with more than one peak that is asymmetric about an axis, the light emitting device optical axis is an angularly weighted average of the luminous intensity output. For non-planar output surfaces, the light emitting device optical axis is evaluated in two orthogonal output planes, and may be a constant direction in a first output plane, and may be a varying angle in a second output plane orthogonal to the first. For example, light emitted from a cylindrical light emitting surface may have a peak angular luminous intensity (and thus the light emitting device optical axis) in a light output plane that does not include the curved output surface profile, and the angle of the luminous intensity may be substantially constant around the axis of rotation of the cylindrical surface on the output plane that includes the curved surface profile. Thus, in this example, the peak angular intensity is a range of angles. When the light emitting device has an optical axis of the light emitting device within the angular range, the optical axis of the light emitting device includes the angular range or a selected angle within the range. The optical axis of a lens or element is the direction having a degree of rotational symmetry in at least one plane and, as used herein, corresponds to the mechanical axis. The optical axis of a region, surface, area or collection of lenses or elements may be different from the optical axis of the lens or element and, as used herein, depends on the angular and spatial profile of the incident light, for example in off-axis illumination of the lens or element.

Optical input coupler

In one embodiment, the light input-coupler comprises a plurality of coupling light guides arranged to receive light emitted from the light source and to guide the light into the light guides. In one embodiment, the plurality of coupling lightguides are strips cut from the lightguide film such that each coupling lightguide strip remains uncut on at least one edge, but can be rotated or positioned (or translated) substantially independently of the lightguide to couple light through at least one edge or surface of the strip. In another embodiment, the plurality of coupling lightguides are not cut from the lightguide film, but are optically coupled to the light source and lightguide, respectively. In another embodiment, a light emitting device includes a light input coupler having a core region of core material and a cladding region or layer of cladding material on at least one surface or edge of the core material, the cladding material having a refractive index less than the refractive index of the core material. In another embodiment, the light input-coupler comprises a plurality of coupling light guides, wherein a portion of the light from the light source incident on the surface of the at least one strip is guided into the light guides such that the light travels under waveguiding conditions. The optical input-coupler may further comprise one or more of: a strip folding device, a strip holding element and an input surface optical element.

In one embodiment, the first array of light input-couplers is positioned to input light into the light mixing region, the light emission region or the light guide region, and the separation distance between the light input-couplers is varied. In one embodiment, a light emitting device includes at least three light input couplers arranged along a side of a film, a separation distance between a first pair of input couplers along the side of the film being different from a separation distance between a second pair of input couplers along the side of the film. For example, in one embodiment, the separation distance between a first pair of input-couplers along the side of the film is greater than the separation distance between a second pair of input-couplers along the side of the film.

Light source

In one embodiment, a light emitting device comprises at least one light source selected from the group consisting of: fluorescent lamps, cylindrical cold cathode fluorescent lamps, flat fluorescent lamps, light emitting diodes, organic light emitting diodes, field emission lamps, gas discharge lamps, neon lamps, filament lamps, incandescent lamps, electroluminescent lamps, radioactive fluorescent lamps, halogen lamps, incandescent lamps, mercury vapor lamps, sodium vapor lamps, high pressure sodium lamps, metal halide lamps, tungsten lamps, carbon arc lamps, electroluminescent lamps, lasers, photonic band gap based light sources, quantum dot based light sources, high efficiency plasma light sources, microplasma lamps. The light emitting device may comprise a plurality of light sources arranged in an array on opposite sides of the light guide, on orthogonal sides of the light guide, on 3 or more sides of the light guide, or on 4 sides of the substantially planar light guide. The array of light sources may be a linear array with discrete LED packages comprising at least one LED die. In another embodiment, a light emitting device includes a plurality of light sources within a package, the plurality of light sources arranged to emit light toward a light input surface. In an embodiment, the light emitting device comprises more than 1, 2, 3, 4, 5, 6, 8, 9, 10 or 10 light sources. In another embodiment, the light emitting device comprises an organic light emitting diode configured to emit light as a light emitting film or sheet. In another embodiment, the light emitting device comprises an organic light emitting diode arranged to emit light into the light guide.

In one embodiment, a light emitting apparatus includes at least one broadband light source that emits light having a wavelength spectrum greater than 100 nanometers. In another embodiment, a light emitting device includes at least one narrow band light source that emits light at a narrow bandwidth of less than 100 nanometers. In another embodiment, a light emitting apparatus includes at least one broadband light source that emits light having a wavelength spectrum greater than 100 nanometers, and in another embodiment, a light emitting apparatus includes at least one broadband light source that emits light having a wavelength spectrum greater than 100 nanometers or at least one narrowband light source that emits narrowband light having a wavelength less than 100 nanometers. In one embodiment, a light emitting apparatus includes at least one narrow band light source having a peak wavelength in a range selected from the group consisting of: 300nm-350nm,350nm-400nm,400nm-450nm,450nm-500nm,500nm-550nm, 550nm-600nm, 600nm-650nm,650nm-700nm,700nm-750nm,750nm-800nm and 800nm-1200nm. The light sources may be selected to match the spectral characteristics of red, green and blue so that, when used in a light emitting device for use as a display, the gamut area is at least one selected from the group consisting of: 70% NTSC,80%, 90% NTSC,100% of the NTSC and standard viewer's visible CIEu ' v ' color gamut, 60%,70%,80%,90% and 95%. In one embodiment, the at least one light source is a white LED package comprising red, green and blue LEDs.

In another embodiment at least two light sources with different colors are arranged to couple light into the light guide through at least one light input coupler. In another embodiment, a light emitting device comprises at least three light input couplers, at least three light sources of different colors (e.g. red, green and blue) and at least three light guides. In another embodiment, the light source further comprises at least one selected from the group consisting of: reflective optical apparatus, mirrors, cups, collimators, primary optics, secondary optics, collimating lenses, compound parabolic collimators, lenses, reflective regions and in-coupling optics. The light source may also include optical path folding optics, such as a curved reflector, which may orient the light source (and possibly the heat sink) along different edges of the light emitting device. The light source may further comprise photonic band gap structures, nanostructures or other three-dimensional arrangements providing an angle FWHM of light output smaller than one selected from the group: 120 degrees, 100 degrees, 80 degrees, 60 degrees, 40 degrees, 20 degrees.

In another embodiment, a light emitting apparatus includes a light source that emits light at a full width at half maximum intensity of one of less than 150 degrees, 120 degrees, 100 degrees, 80 degrees, 70 degrees, 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, and 10 degrees. In another embodiment, the light source further comprises at least one selected from the group consisting of: a primary optic, a secondary optic, and a photonic band gap region, and the light source has a full width at half maximum intensity at an angle less than one selected from the group consisting of 150 degrees, 120 degrees, 100 degrees, 80 degrees, 70 degrees, 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, and 10 degrees.

LED array

In one embodiment, the light emitting device comprises a plurality of LEDs or LED packages, wherein the plurality of LEDs or LED packages comprises an array of LEDs. The array components (LEDs or electrical components) may be physically (and/or electrically) coupled to a single circuit board, or they may be coupled to multiple circuit boards that may or may not be directly physically coupled (i.e., such as not on the same circuit board). In one embodiment, the LED array is an array comprising at least two selected from the group of: red, green, blue and white LEDs. In this embodiment, white point variations due to manufacturing or component variations may be reduced. In another embodiment, the LED array comprises at least one cold white LED and one red LED. In this embodiment, the CRI or color rendering index is higher than that of cold white LED illumination alone. In one embodiment, the CRI of at least one selected from the group of: a light emitting area, a light emitting surface, a luminaire, a light emitting device, a display including a light emitting device driven in a white mode, and a symbol greater than one selected from at least one of the following groups: 70. 75, 80, 85, 90, 95 and 99. In another embodiment, the NIST Color Quality Scale (CQS) of at least one selected from the group consisting of: a light emitting area, a light emitting surface, an illumination device, a light emitting device, a display (including a light emitting device) driven in a white mode or a symbol larger than one selected from the group consisting of: 70. 75, 80, 85, 90, 95 and 99. In another embodiment, the color gamut of the display including the light emitting device is greater than 70%,80%,85%,90%,95%,100%,105%, 110%,120%, and 130% of the NTSC standard color gamut. In another embodiment, the LED array includes white, green, and red LEDs. In another embodiment, the LED array comprises at least one green and blue LED and two types of red LEDs, wherein one type has a lower luminous efficiency or wavelength than the other type of red LEDs. As used herein, a white LED may be a phosphor converted blue LED or a phosphor converted UVLED.

In another embodiment, the input array of LEDs may be arranged to compensate for non-uniform absorption of light through a longer, relatively shorter light guide. In another embodiment, absorption is compensated for by directing more light into the light input-coupler corresponding to the longer coupling light guide or longer light guide. In another embodiment, more light within the first wavelength band is absorbed by the light guide than light within the second wavelength band, and a first ratio of radiant flux coupled into the light input coupler within the first wavelength band divided by radiant flux coupled into the light input coupler within the second wavelength band is greater than a second ratio of radiant flux emitted by the light emitting area within the first wavelength band divided by radiant flux emitted by the light emitting area within the second wavelength band.

Laser

In one embodiment, the light emitting device comprises one or more lasers arranged to couple light into the surface of one or more light input couplers or one or more coupling light guides. In one embodiment, the divergence of the one or more light sources is less than a light source selected from the group consisting of: 20 mrad, 10 mrad, 5 mrad, 3 mrad and 2 mrad. In another embodiment, the light mixing region comprises a light scattering or light reflecting region that increases the angle FWHM of light from the one or more lasers within the light mixing region before entering the light emitting region or light emitting surface region of the light guide. In another embodiment, the light scattering area within the light mixing area is a volumetric or surface light scattering area, wherein the transmitted light has an angle FWHM less than one selected from the group consisting of: 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees, 5 degrees and 2 degrees, when measured perpendicular to the large area surface of the film in this region with a 532nm laser diode with a divergence of less than 5 milliradians. In another embodiment, the diffuser in the light mixing region has a haze, when measured perpendicular to the large area surface of the film (e.g., parallel to the light emission surface), that is less than a haze selected from the group consisting of: 50%,40%,30%,20%,10%,5% and 2%.

Color adjustment

In one embodiment, the light emitting device comprises two or more light sources, and the relative outputs of the two light sources are adjusted to achieve a desired color in the area of light output over the light emitting area of the light guide or over the light emitting areas comprising a plurality of light guides overlapping in that area. For example, in one embodiment, the light emitting device comprises red, green and blue LEDs arranged to couple light into the stacked light input surfaces of the coupling light guide. The light is mixed within the light guide and output in the light emitting area of the light guide. For example, by turning on the red and blue LEDs, a violet light emitting area can be achieved. In another embodiment, the relative light output of the light sources is adjusted to compensate for non-uniform spectral absorption in the optical elements of the light emitting device. For example, in one embodiment, the output of a blue LED in milliwatts is increased to a higher level than the red output in milliwatts to compensate for more blue light absorption (or blue light scattering) in the light guide so that the light emitting region has a substantially white light output in a particular region.

LED array position

In one embodiment, multiple arrays of LEDs are provided to couple light into a single light input coupler or more than one light input coupler. In yet another embodiment, a plurality of LEDs disposed on the circuit board are arranged to couple light into a plurality of light input couplers that direct light to a plurality of sides of a light emitting device that includes a light emitting area. In a further embodiment, the light emitting device comprises an array of LEDs and a light input coupler folded behind a light emitting area of the light emitting device such that the array of LEDs and the light input coupler are not visible when the center of the light emitting area is viewed at an angle perpendicular to the surface. In another embodiment, the light emitting device comprises a single LED array arranged to couple light into at least one light in-coupler arranged to direct light from a bottom region of the light emitting device into the light emitting region. In an embodiment, the light emitting device comprises a first LED array and a second LED array arranged to couple light into a first light input coupler and a second light input coupler, respectively, wherein the first light input coupler and the second light input coupler are arranged. Light is caused to enter the light emitting region from the top and bottom regions of the light emitting device, respectively. In another embodiment, a light emitting device includes a first LED array, a second LED array, and a third LED array arranged to couple light into a first light input coupler, a second light input coupler, and a third light input coupler, the first light input coupler, the second light input coupler, and the third light input coupler each arranged to direct light into the light emitting region from a bottom region, a left region, and a right region, respectively, of the light emitting device. In another embodiment, a light emitting device includes a first LED array, a second LED array, a third LED array, and a fourth LED array arranged to couple light into a first light input coupler, a second light input coupler, a third light input coupler, and a fourth light input coupler, the first light input coupler, the second light input coupler, the third light input coupler, and the fourth light input coupler being arranged to direct light into the light emitting area from a bottom region, a left region, a right region, and a top region, respectively, of the light emitting device.

Wavelength conversion material

In another embodiment, the LED is a blue or ultraviolet LED combined with a phosphor. In another embodiment, a light emitting device includes a light source having a first activation energy and a wavelength conversion material that converts a first portion of the first activation energy to a second wavelength different from the first wavelength. In another embodiment, the light emitting device comprises a wavelength converting material selected from at least one of: fluorophores, phosphors, fluorescent dyes, inorganic phosphors, photonic band gap materials, quantum dot materials, fluorescent proteins, fusion proteins, fluorophores attached to proteins, fluorophores with specific functional groups (e.g. amino groups (active esters, carboxylic esters, isothiocyanates, hydrazines), carboxyl groups (carbodiimides), thiols (maleimides, acetyl bromides), azides (by click chemistry or non-specifically (glutaraldehyde))), quantum dot fluorophores, small molecule fluorophores, aromatic fluorophores, conjugated fluorophores, fluorescent dyes and other wavelength converting materials.

In one embodiment, the light source includes a semiconductor light emitter, such as an LED, and a wavelength conversion material that converts a portion of the light from the light emitter to shorter or longer wavelengths. In another embodiment, at least one selected from the group of: the light input coupler, cladding region, coupling lightguide, input surface optics, coupling optics, light mixing region, lightguide, light extraction features or regions and light emission surface comprise a wavelength converting material.

Optical input coupler input surface

In one embodiment, the light input-coupler comprises a collection of coupling lightguides having a plurality of edges forming an input surface of the light-coupler. In another embodiment, an optical element is disposed between the light source and the at least one coupling light guide, wherein the optical element receives light from the light source through the optical coupler input surface. In some embodiments, the input surface is substantially polished, flat, or optically smooth, so that light is not scattered forward or backward from pits, bumps, or other rough surface features. In some embodiments, an optical element is disposed between the light source and the at least one coupling lightguide to provide light redirection as an input surface (when optically coupled to the at least one coupling lightguide) or as an optical element alone or optically coupled to the at least one coupling lightguide such that more light is redirected into the lightguide at an angle greater than a critical angle within the lightguide than without the optical element or with a flat input surface. The plurality of coupling lightguides may be grouped together such that edges opposite the lightguide regions are brought together to form an input surface that includes their thin edges.

Stacked strips or segments of thin film forming light input couplers

In one embodiment, the light input-coupler is a region of film comprising light guides and the light input-coupler comprises strip-like portions forming a film coupling the light guides, which are grouped together to form a light-coupler input surface. The plurality of coupling lightguides may be grouped together such that edges opposite the lightguide regions are brought together to form an input surface that includes their thin edges. A planar input surface for a light input coupler may provide beneficial refraction to redirect a portion of the input light from that surface to an angle so that it propagates at an angle greater than the critical angle of the light guide. In another embodiment, a substantially planar optically transmissive element is optically coupled to the grouped edges of the coupling light guide. One or more edges of the plurality of coupling lightguides may be polished, melted, smoothed with a caustic or solvent material, adhered with an optical adhesive, solvent welded, or otherwise optically coupled along a region of the edge surface to substantially polish, smooth, flat, or substantially planarize the surface.

In one embodiment, the lateral edges of at least one selected from the group of: the light-diverting lateral edge of the coupling lightguide, the light-collimating lateral edge of the coupling lightguide, the lateral edge of the lightguide region, the lateral edge of the light-mixing region, and the lateral edge of the light-emitting region include an optically smooth material disposed in the edge region that reduces a surface roughness of a region of the edge in at least one of a lateral direction and a thickness direction. In one embodiment, the optically smooth material fills the gaps, grooves, scratches, pits, indentations, flattens the area around the protrusion or other optical blur to allow more light to be totally internally reflected from the surface within the core area of the coupling light guide.

The light input surface may comprise a surface of an optical element, a surface of an adhesive, a surface of more than one optical element, a surface of one or more coupling edges of the light guide, or a combination of one or more of the foregoing. The light input-coupler may also include an optical element having an opening or window, wherein a portion of the light from the light source may enter the coupling light guide directly without passing through the optical element. The optical input-coupler or an element or region therein may also include a cladding material or region.

Light redirecting optical device

In one embodiment, the light redirecting optical element is configured to receive light from at least one light source and redirect the light into the plurality of coupling lightguides. In another embodiment, the light redirecting optical element is at least one selected from the group consisting of: secondary optics, mirror elements or surfaces, reflecting films, e.g. aluminized PET, e.g. Vikuiti from 3M company ^TM A giant birefringent optical film of enhanced specular reflection film, a curved mirror, a total internal reflection element, a dichroic mirror, and a dichroic mirror or film.

Optical collimating element

In one embodiment, the light input-coupler comprises a light collimating optical element. The light collimating optical element receives full width angular light at a first half maximum intensity from the light source in at least one input plane and redirects a portion of the incident light from the light source such that the full width angular light at the half maximum intensity of the light is reduced in the first input plane. In one embodiment, the light collimating optical element is one or more of: a light source primary optic, a light source secondary optic, a light input surface, and an optical element disposed between the light source and the at least one coupling lightguide. In another embodiment, the light collimating element is one or more of: injection molded optical lenses, thermoformed optical lenses and crosslinked lenses made from molds. In another embodiment, the light collimating element reduces a full width at half maximum intensity (FWHM) in the input plane and a plane orthogonal to the input plane.

In one embodiment, a light emitting device includes a light input-coupler and a thin film based light guide. In one embodiment, the light input-coupler comprises light sources and a light collimating optical element arranged to receive light from the one or more light sources and provide a light output in a first output plane, a second output plane orthogonal to the first plane, or both output planes, the light output having a full width at half maximum intensity in air that is less than one selected from the group consisting of: the optical axis of the light emitted from the autocollimation optical element is 60 degrees, 40 degrees, 30 degrees, 20 degrees and 10 degrees.

In one embodiment, the collimation or reduction of the angular FWHM intensity of the light from the light collimating element is substantially symmetric about the optical axis. In one embodiment, the light collimating optical element receives light from a light source having a substantially symmetric angular FWHM intensity about the optical axis that is greater than one selected from the group consisting of: 50. 60, 70, 80, 90, 100, 110, 120, and 130 degrees and provides output light having an angular FWHM intensity that is less than a selected one of the optical axes 60, 50, 40, 30, and 20 degrees. For example, in one embodiment, a light collimating optical element receives light from a white light LED having an angular FWHM intensity of about 120 degrees symmetric about its optical axis and provides output light at an angular FWHM intensity of about 30 degrees from the optical axis.

The full width at half maximum intensity of light propagating within the light guide can be determined by measuring the far field angular intensity output of the light guide from an optical quality end cut perpendicular to the film surface and calculating and adjusting for refraction at the air-light guide interface. In another embodiment, the full width at half maximum intensity of light extracted from one or more light extraction features of the film-based lightguide or the light extraction regions comprising the light extraction features is less than one selected from the group consisting of: 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees and 5 degrees. In another embodiment, the peak angular intensity of light extracted from the light extraction features is within 50 degrees of the surface normal of the lightguide within the region. In another embodiment, the full width at angle at far field full half maximum intensity of light extracted from the light emission region of the film-based light guide is less than one selected from the group consisting of: 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees, and 5 degrees, and the peak angular intensity is within 50 degrees of a surface normal of the light guide in the light emission region.

Coupling light guide

In one embodiment, the coupling light guide is a region within which light can propagate under waveguiding conditions, and a portion of the light input into a surface or region of the coupling light guide passes through the coupling light guide towards the light guide or light mixing region. In some embodiments, the coupling lightguide may be used to geometrically transform a portion of the flux from the light source from a first shaped region to a second shaped region different from the first shaped region. In an example of this embodiment, the light input surface of the light input coupler formed by the edges of the folded strip of planar film (the coupling light guide) has rectangular dimensions of 3 mm by 2.7 mm, and the light input coupler couples light into a planar portion of the film located in the mixing region, the planar portion having cross-sectional outer dimensions of 40.5 mm by 0.2 mm. In an embodiment, the direction of extension of the one or more coupling lightguides is the direction in which the one or more coupling lightguides extend from the common base area.

Folding and bending of coupled light guides

In one embodiment, a light emitting device includes a light mixing region disposed between a light guide and strips or segments cut to form a coupling light guide with edges of the strips or segments brought together to form a light input surface of a light input coupler, the light input coupler being disposed to receive light from a light source. In one embodiment, the light input-coupler comprises a coupling light guide, wherein the coupling light guide comprises at least one fold or bend in a plane such that at least one edge overlaps another edge. In another embodiment, the coupling light guide comprises a plurality of folds or bends, wherein the edges of the coupling light guide may be connected together in an area such that the area forms the light input surface of the light input coupler of the light emitting device. In one embodiment, at least one coupling light guide comprises a strip or segment that is bent or folded to a radius of curvature that is less than 75 times the thickness of the strip or segment. In another embodiment, the at least one coupling light guide comprises a strip or segment that is bent or folded to a radius of curvature that is greater than 10 times the thickness of the strip or segment. In another embodiment, at least one of the coupling light guides is bent or folded such that the longest dimension of a cross-section through the light emitting device or the coupling light guide in at least one plane is smaller than the dimension without folding or bending. The segments or strips may be bent or folded in more than one direction or area, and the direction of folding or bending may differ between strips or segments.

Coupling light guide lateral edges

In one embodiment, a lateral edge is defined herein as an edge of a coupling light guide that does not substantially receive light directly from a light source, and is not part of the edge of the light guide area. The lateral edges of the coupling light guide receive substantially only light from light propagating within the coupling light guide. In one embodiment, the lateral edge is at least one selected from the group consisting of: uncoated, coated with a reflective material, disposed adjacent to the reflective material, and cut with a particular cross-sectional profile. The side edges may be coated, bonded, or otherwise disposed adjacent to the specular, partially diffuse, or diffuse reflective material. In one embodiment, the edges are coated with a specularly reflective ink comprising nano-sized or micro-sized particles or flakes that substantially specularly reflect light when the coupling lightguides are brought together due to folding or bending. In another embodiment, a light reflecting element (e.g., a multilayer specular polymer film with high reflectivity) is disposed near the lateral edges of at least one region of the disposed coupling lightguide, and the multilayer specular polymer film with high reflectivity is disposed to receive light from the edges and reflect it and direct it back into the lightguide. In another embodiment, the lateral edges are rounded and reduce the percentage of incident light that is diffracted out of the light guide from the sides. One way to obtain a rounded edge is by cutting a strip, segment or coupled-light guide region from a film using a laser and rounding the edge by controlling the processing parameters (cutting speed, cutting frequency, laser power, etc.). Other methods of producing rounded edges include mechanical grinding/polishing or chemical/vapor polishing. In another embodiment, the lateral edges of the regions of the coupling lightguides are tapered, angled, serrated, or otherwise cut or shaped such that light propagating within the coupling lightguides from the light sources is reflected from the edges such that it is directed at an angle closer to the optical axis of the light sources, toward the fold or bend region, or toward the lightguide or lightguide region.

Width of coupling light guide

In one embodiment, the dimensions of the coupling lightguides are substantially equal to each other in width and thickness such that the input surface area of each edge surface is substantially the same. In another embodiment, the average width w of the coupling lightguides is determined by the following equation: w = MF W _LES /NC, wherein, W _LES Is the total width of the light emission surface in a direction parallel to the light entrance edge of the lightguide region or lightguide receiving light from the coupling lightguide, NC is the total number of coupling lightguides in a direction parallel to the light entrance edge of the lightguide region or lightguide receiving light from the coupling lightguide, and MF is the magnification factor. In one embodiment, the amplification factor is one selected from the group consisting of: 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 0.7-1.3, 0.8-1.2 and 0.9-1.1. In another embodiment, at least one selected from the group of: the coupling light guide width, the maximum width of the coupling waveguide, the average width of the coupling light guides and the width of each coupling light guide are selected from the group consisting of: 0.5mm-1mm,1mm-2mm,2mm-3mm,3mm-4mm,5mm-6mm,0.5mm-2mm, 0.5mm-25mm,0.5mm-10mm,10-37mm and 0.5mm-5mm. In one embodiment, at least one selected from the group of: the coupling light guide width, the maximum width of the coupling waveguide, the average width of the coupling light guides, and the width of each coupling light guide are less than 20 millimeters.

In one embodiment, the ratio of the average width of the coupling lightguide, which is arranged to receive light from the first light source, to the average thickness of the coupling lightguide is greater than one selected from the group consisting of: 1. 2, 4, 5, 10, 15, 20, 40, 60, 100, 150 and 200. In another embodiment, a low contact area film is placed between the lateral edge of the contact light guide and the folded portion. In another embodiment, the folded portion includes low contact area surface features such that it provides protection without significant coupling of light from the lateral and/or surface regions of the coupling light guide. In another embodiment, the coupling lightguide includes an adhesive disposed between two regions of the coupling lightguide such that the adhesive adheres to itself and wraps around the stack of coupling lightguides.

Spaces or gaps between coupled light guides

In one embodiment, two or more coupling lightguides include a gap between the lightguides in the region where it connects to the lightguide region, or mixing region. In another embodiment, the light guides are formed by a manufacturing method, wherein gaps are created between the light guides. For example, in one embodiment, the light guides are formed by die cutting a film and the coupling light guides have gaps between them. In an embodiment, the gap between the coupling lightguides is larger than one selected from the group of: 0.15, 0.25, 0.5, 1, 2, 4, 5, 10, 25 and 50 millimeters. In an embodiment, increasing the spacing or gap between the coupling lightguides can reduce the angular shadowing of the light emitting device or display. If the gap between the coupling lightguides is very large relative to the coupling lightguide width, then in some embodiments, the uniformity of the light emitting area may be reduced (with respect to luminance or color uniformity) if the mixing area of the lightguide is not long enough in the direction parallel to the optical axis of the light propagating in the lightguide because one side of the lightguide has an area where light does not enter the lightguide area from the coupling lightguide (the gap area). In one embodiment, the film-based light guide comprises two coupling lightguides, wherein the width of the coupling lightguide divided by the average of the width of the gap between the coupling lightguides is greater than one selected from the group at the area where the coupling lightguide connects the mixing region or lightguide region: 0.1, 0.5, 1, 1.5, 2, 4, 6, 10, 20, 40 and 50. In another embodiment, a thin film based light guide has large gaps between the coupling light guides and a light mixing area long enough to provide the required uniformity. In another embodiment, the film-based light guide comprises two coupling light guides, wherein a width of a gap between the two coupling light guides divided by an average width of the two coupling light guides at a region joining the light mixing region or light guide is greater than one selected from the group consisting of: 1. 1.5, 2, 4, 6, 10, 20, 40 and 50.

Varying spacing between coupled light guides

In one embodiment, the first array of coupling lightguides extends from a lightguide region or body of the film-based lightguide and a separation distance between the coupling lightguides at the lightguide region varies. In another embodiment, a separation distance between two or more coupling lightguides along a first side of a lightguide region of a film-based lightguide is greater than a separation distance between two or more coupling lightguides along the side of the lightguide region. In another embodiment, a first pair of coupling-in lightguides positioned along a side of a lightguide region of a film-based lightguide has a first average length and a first separation distance, and a second pair of coupling-in lightguides disposed along the side of the lightguide region has a second average length and a second separation distance. In one embodiment, the first average length is less than the second average length and the first separation distance is greater than the second separation distance. In another embodiment, the first average length is greater than the second average length and the first separation distance is greater than the second separation distance. In another embodiment, the separation distance between the coupling lightguides along one side of the lightguide region of the film-based lightguide decreases and the length of the coupling lightguides increases. In another embodiment, the two pairs of coupling lightguides are spaced apart by a distance, taper and/or average width that varies along the side of the lightguide region from which the two pairs of coupling lightguides extend,

Edge of light guide region and spacing of nearest coupled light guides to the edge

In one embodiment, the coupling light guide closest to the edge of the film-based light guide is spaced apart from the edge of the film adjacent the side. For example, in one embodiment, a first coupling lightguide along one film-based side is separated from an edge of the lightguide region by a distance greater than 1 mm. In another embodiment, the distance between the first coupling lightguide along the film-based side and the edge of the lightguide region is greater than one selected from the group consisting of: 0.5, 1, 2, 4, 6, 8, 10, 20 and 50 millimeters. In one embodiment, the distance along the side between the edge of the lightguide region and the first coupling lightguide improves the uniformity of the lightguide region as light from the first coupling lightguide is reflected from the lateral edge of the lightguide region.

Profiled or tapered coupling light guides

The width of the coupling lightguides may vary in a predetermined pattern. In one embodiment, when the light input edges of a plurality of coupling lightguides are arranged together to form the light input surface of a light input coupler, the observed width of the coupling lightguides varies from a large width of the central coupling lightguide to a smaller width of the lightguide away from the central coupling lightguide. In this embodiment, a light source having a substantially circular light output aperture may be coupled into a coupling lightguide such that light at higher angles to the optical axis is coupled into a strip of smaller width such that the uniformity of a light emitting surface along the edge of the lightguide or lightguide region and parallel to an input edge of the lightguide region disposed to receive light from the coupling lightguide is greater than one selected from the group consisting of: 60%,70%,80%,90% and 95%.

Other shapes of the stacked coupling light guide are envisaged, such as triangular, square, rectangular, oval etc. which provide a matching input area to the light emitting surface of the light source. The width of the coupling lightguides may also be tapered so that they redirect a portion of the light received from the light source. The lightguide may taper near the light source, in a region along the coupling lightguide between the light source and the lightguide region, near the lightguide region, or some combination thereof.

Here, the shape of the coupling light guide is referred to from the light guide region or the light emission region or the body of the light guide. One or more coupling lightguides extending from a side or region of the lightguide region may expand (widen or widen) or taper (narrow or narrow) in a direction toward the light source. In an embodiment, the coupling lightguide is tapered in one or more regions to provide redirection or partial collimation of light traveling from the light source toward the lightguide region within the coupling lightguide. In an embodiment, one or more coupling lightguides widen along one lateral edge and taper along an opposite lateral edge. In this embodiment, the net effect may be that the width remains constant. The widening or tapering may have a different profile or shape along each side for one or more of the coupling lightguides. The widening, tapering, and contouring of each lateral edge of each coupling light guide may be different, and may be different in different regions of the coupling light guide. For example, one coupling light guide in an array of coupling light guides may have a parabolic tapered profile on both sides of the coupling light guide in the region near the light source to provide partial collimation, and one side edge of the coupling light guide tapers at a linear angle at about 50% of the length of the region, while the other side includes a parabolic edge. Tapering, widening, profile shape, profile location, and number of profiles along each lateral edge may be used to provide control of one or more selected from the group consisting of: the spatial or angular color uniformity of light exiting the coupling lightguide into the light mixing region (or light emission region), the spatial or angular luminance uniformity of light exiting the coupling lightguide into the light mixing region (or light emission region), the angular redirection of light entering the light mixing region (or light emission region) of the lightguide (which may affect the angular light output profile of light exiting the light emission region as well as the shape, size, and type of light extraction features), the relative luminous flux distribution within the light emission region, and other light redirection advantages such as, but not limited to, redirecting more light to the second extended light emission region.

Inner light guide edge

In one embodiment, one or more of the inner region of the coupling light guide, the light mixing region, the light guide region or the light emission region comprises one or more inner light guiding edges. The inner light guiding edge may be formed by cutting or otherwise removing an inner region of the coupling light guide, light mixing region, light guiding region or light emission region. In one embodiment, the inner light guiding edge redirects a first portion of light within the coupling light guide, light mixing region, light guide region, or light emission region. In one embodiment, the inner light guiding edge provides an additional level of control for guiding light within the coupling light guide, light mixing region, light guide region, or light emission region, and may provide flux redistribution within the coupling light guide, light mixing region, light guide region, and/or light emission region to achieve a predetermined light output pattern (e.g., higher uniformity or higher flux output) within a particular region.

In one embodiment, at least one inner light guiding edge is located within the coupling light guide, light mixing region, light guide region, or light emission region to receive light propagating within the coupling light guide, light mixing region, light guide region, or interior. The light emitting regions are each within a first angular range from the optical axis of light propagating within the coupling lightguide or region and direct light into a different second angular range propagating within the coupling lightguide or region. In one embodiment, the first angular range is selected from the group consisting of: 70-89, 70-80, 60-80, 50-80, 40-80, 30-80, 20-80, 30-70, and 30-60 degrees; and the second angular range is selected from the group of: 0-10 degrees, 0-20 degrees, 0-30 degrees, 0-40 degrees, 0-50 degrees, 10-40 degrees and 20-60 degrees. In an embodiment, the plurality of inner light guide edges are formed after the coupling light guides are stacked. In another embodiment, one or more of the coupling lightguide, the light mixing region, the lightguide region, and the light emitting region have internal lightguide edges that form channels that spatially separate light propagating within the coupling lightguide. In one embodiment, the length of the optical axis of light traveling along the coupling lightguide, light mixing region, lightguide region, or light emitting region by the one or more inner lightguide edges is greater than one selected from the group consisting of: 20%,30%,40%, 50%,60%,70%,80% and 90%. In another embodiment, the inner light guide edge is positioned within one selected from the group of: 1, 5, 7, 10, 15, 20, 25 millimeters from an input surface of the coupling lightguide, a boundary where the coupling lightguide intersects a lightguide region or a lightguide mixing region, or a boundary between a lightguide mixing region and a light emitting region of the film-based lightguide. In one embodiment, one or more of the coupling lightguides has an inner lightguide edge positioned within a selected one of the group: 1, 5, 7, 10, 15, 20, 25 millimeters from the light input surface of the one or more coupling lightguides. In another embodiment, the one or more coupling lightguides have at least one inner lightguide edge with a width in a direction parallel to the fold line that is greater than one selected from the group consisting of: 5%, 10%, 15%, 20%,25%, 30%,35%,40%,45%,50% and 60% of the width of the coupling lightguide at the lightguide region. In another embodiment, the at least one coupling lightguide has two adjacent inner lightguide edges, wherein the average spacing between the inner lightguide edges in a direction parallel to the fold line is greater than one selected from the group consisting of: 5%, 10%, 15%, 20%,25%, 30%,35%,40%,45%,50% and 60% of the width of the coupling lightguide at the lightguide region.

In another embodiment, at least one of the coupling lightguides, the light mixing region, the lightguide region, or the light emitting region includes a plurality of channels defined by at least one inner lightguide edge and a lateral edge of the coupling lightguide or the light coupling region. In another embodiment, the coupling light guide, the light mixing region, the light guiding region or the light emission region comprises a channel defined by a first inner light guide edge and a second inner light guide edge. In one embodiment, one or more channels defined by the internal light-directing edges and/or lateral edges of the coupling light guide, light-mixing region, light guide region, or light emission region divide the angular range of light from the light source into a plurality of spatially separable channels that transfer the spatial separation to the light guide region, light emission region, or light emission region. In one embodiment, the channels are parallel to the direction of extension of the array of coupling lightguides. In another embodiment, the light sources comprise a plurality of light emitting diodes formed in an array such that the optical axis of a first light source enters a first channel defined in the coupling light guide and the optical axis of a second light source enters a second channel defined in the coupling light guide. In another embodiment, one or more inner light guiding edges extend from inside the one or more coupling lightguides into a lightguide region of the lightguide. In another embodiment, the lightguide region has one or more inner lightguide edges. In another embodiment, the lightguide region has one or more interior lightguide edges and the one or more coupling lightguides include one or more interior lightguide edges. In another embodiment, one or more inner light guide edges extend from inside the one or more coupling light guides into the light emission area of the light guide. In this embodiment, for example, light sources comprising red, green and blue light emitting diodes in a linear array, respectively adjacent to the first, second and third channels of the plurality of coupling lightguides, may be directed to alternating first, second and third pixel regions within the light emission area to create a repeating spatial arrangement of red, green, blue, red, green, blue color pixels in the light emission area of the color display or color marker. In another embodiment, the inner region of the light-mixing region or the light-guiding region comprises at least one inner light-guiding edge.

Coupling light guide orientation angles

In another embodiment, at least a portion of the array of coupling lightguides is disposed at a first coupling lightguide orientation angle, at least one coupling lightguide orientation angle guiding light into an edge of the mixing region and the light emitting region. The coupling light guide orientation angle is defined as the angle between the coupling light guide axis and the direction parallel to the major component of the direction of the coupling light guide to the light emission area of the light guide. The main component of the direction of the coupling lightguides to the light emission area of the lightguide is orthogonal to the array direction of the array of coupling lightguides at the light mixing area (or lightguide area if they extend directly from the light emission area). In one embodiment, the orientation angle of the coupling light guide or the average orientation angle of the plurality of coupling light guides is at least one selected from the group consisting of: 1-10 degrees, 10-20 degrees, 20-30 degrees, 30-40 degrees, 40-50 degrees, 60-70 degrees, 70-80 degrees, 1-80 degrees, 10-70 degrees, 20-60 degrees, 30-50 degrees, greater than 5 degrees, greater than 10 degrees, and greater than 20 degrees.

Unfolded coupling light guide

In another embodiment, a film-based light guide includes an unfolded coupling light guide that is configured to receive light from a light input surface and direct the light to a light guide region without turning the light. In an embodiment, the unfolded light guide is used in conjunction with one or more light turning optical elements, light coupling optical elements, coupling light guides with light turning edges, or coupling light guides with collimating edges. For example, the light turning optical element may be disposed above or below the unfolded coupling light guide such that light from the first portion of the light source substantially maintains its optical axis direction as it passes through the unfolded coupling light guide and the mirror, while light from the light source received by the light turning optical element is turned into the stack of arrays of coupling light guides. In another embodiment, the array stack of coupling lightguides comprises a folded coupling lightguide and an unfolded coupling lightguide.

In another embodiment, the unfolded coupling light guide is arranged near an edge of the light guide. In one embodiment, the unfolded coupling light guide is arranged in the middle area of the edge of the light guide area. In a further embodiment, an unfolded coupling light guide is disposed along one side of the light guide region at a region between the lateral sides of the light guide region. In one embodiment, unfolded coupling light guides are provided at each region along one edge of the light guide region, wherein a plurality of light input couplers are used to guide light to one side of the light guide region.

In another embodiment, the folded coupling light guide has a light collimating edge, a substantially linear edge, or a light turning edge. In one embodiment, at least one selected from the group consisting of: the array of folded coupling lightguides, the light turning optical element, the light collimating optical element, and the light source are physically coupled to the unfolded coupling lightguide. In another embodiment, the folded coupling lightguides are physically coupled to each other and to the unfolded coupling lightguides by the pressure sensitive adhesive cladding layer, and the unconstrained lightguide film comprising the light-emissive region and the array of coupling lightguides has a thickness less than one of: 1.2 times, 1.5 times, 2 times, and 3 times the thickness of the array of coupling lightguides. By only bonding the folded coupling lightguide to itself, the coupling lightguide (when unconstrained) typically bends upward and increases the thickness of the array since the folded coupling lightguide is not physically coupled to a fixed or relatively constrained region. By physically coupling the folded coupling lightguide to the unfolded coupling lightguide, the array of coupling lightguides is physically coupled to a separate area of the film, which increases stability, thus reducing the ability of the stored elastic energy to be released due to bending.

Coupling light guide stack

In one embodiment, light is emitted from a film-based light sourceThe coupling lightguides extending from the lightguide region in the lightguide are folded at a 90 degree fold angle and their ends are stacked. In this embodiment, the radius of curvature of each coupling light guide is different due to the different thickness of each coupling light guide. In this embodiment, the radius of curvature of the nth coupling light guide is determined by the following equation:

where R1 is the initial (minimum radius) coupling lightguide radius and t is the thickness of the coupling lightguide.

The coupling light guide may configure the coupling light guide stack in a variety of ways to compensate for different radii of curvature. In one embodiment, the coupling light guide has one or more compensation features selected from the group consisting of: interleaved light input surfaces; coupling light guides angularly oriented with respect to each other; different transverse fold positions; coupling light guides angled in a directional stack; uneven tension or torsion; the radius of curvature of the folds of the stack is constant, and other compensation techniques or features.

Sacrificial coupling light guide

In one embodiment, the light input-coupler comprises an array stack of coupling lightguides comprising at least one sacrificial coupling lightguide. In another embodiment, a film-based light guide includes a sacrificial coupling light guide on one or both ends of an array of coupling light guides extending from a light guide region of a film. In one embodiment, the sacrificial coupling light guide is folded, stacked and positioned to couple into the coupling light guide under total internal reflection conditions, the percentage of total luminous flux of the light source from the light input-coupler being selected from the group consisting of: 0%, less than 1%, less than 2%, less than 5% and less than 10%. In this embodiment, for example, the envelope, housing, RPME or other element of the light emitting device may be physically or optically coupled to the sacrificial lightguide such that the light output of the light emitting device is not significantly reduced by absorption of light in the stack of coupling lightguides or scattering of light into the top or bottom coupling lightguides. In one embodiment, one or both of the sacrificial coupling light guides are cut to a length such that when the array of coupling light guides is folded and stacked, the distance along the length of the fold, stack, to the input surface of the remaining coupling light guides in the array of coupling light guides of the end of the one or both sacrificial coupling light guides is greater than one of: 1. 2, 5, 10, 15, 20, 40, 50, 100 and 200 millimeters. In this embodiment, the light input surface formed by the end edges of the remaining, non-sacrificial coupling light guides can be positioned to receive light from the light sources, and one or both sacrificial coupling light guides and/or the position of light blocking elements disposed between the ends of one or more sacrificial coupling light guides and the light sources, prevent a significant amount of flux (e.g., greater than 5%) from entering the sacrificial coupling light guides under total internal reflection conditions. In one embodiment, one or both sacrificial coupling lightguides do not substantially "wet out" (optically couple across the interface such that the total internal reflection condition is transferred from the first region to the second region) with its adjacent coupling lightguides in the stack. In this embodiment, an air gap between one or both sacrificial coupling lightguides can prevent the sacrificial coupling lightguide from transferring or decoupling light from its adjacent coupling lightguides, so that the housing, RPME, or light absorbing wrap can be physically coupled to the sacrificial coupling lightguide (e.g., a light absorbing black tape wrapped around the coupling lightguide stack, causing it to adhere to the top and bottom sacrificial coupling lightguides) without concern for light absorption, since light from the light source does not substantially propagate through the sacrificial coupling lightguide. In one embodiment, the width of the sacrificial coupling light guide is greater than the width of the intermediate coupling light guide in the coupling light guide stack. In this embodiment, the wider width of the sacrificial coupling light guide can allow the adhesive wrap to extend around and over the top and side cover regions of the sacrificial light guide without contacting one or more lateral edges of the intermediate coupling light guide (leaving an air gap between the wrap and the lateral edges) so that it does not absorb or decouple light from the top coupling light guide and the side edges of the one or more intermediate coupling light guides, because the adhesive of the wrap does not contact the top surface of the top coupling light guide (which may be in contact with the top sacrificial coupling light guide that does not include significant light flux, if any) or the lateral edge surfaces of the coupling light guide. In one embodiment, the width of the sacrificial coupling light guide is greater than the width of the intermediate coupling light guide in the stack of coupling light guides, and portions of one or both sacrificial coupling light guides are bent towards the lateral edges of the remaining coupling light guides. For example, in this embodiment, the curved regions of the sacrificial coupling lightguide may help prevent wetting, decoupling, or absorption of light from the top coupling lightguide outer surface and the lateral edges of the middle coupling lightguide stack by providing an intermediate non-wetting layer that may prevent the lateral edges from optically coupling with an element, such as the light absorbing layer comprising an adhesive, RPME, housing, or other element. In one embodiment, the wider sacrificial coupling light guide is perforated in one region (e.g., a linear region defined laterally by the lateral edges of the stack of intermediate coupling light guides) so that the sacrificial coupling light guide can be easily bent and its side-covered region of the film surface is substantially parallel to the lateral edge surface of the intermediate coupling light guide. In an embodiment, one or more surfaces of the sacrificial coupling light guides may be roughened or include surface relief features, regions, or layers such that the surface relief features are positioned between lateral edges of the one or two sacrificial coupling light guides and the intermediate coupling light guide, or outer (non-lateral edge) surfaces of outer intermediate coupling light guides adjacent to the one or two sacrificial coupling light guides.

Light mixing region

In one embodiment, a light emitting device includes a light mixing region disposed on an optical path between a light input coupler and a light guide region. The light mixing regions may provide for mixing together of the light output from the respective coupled light guides and improve any combination of spatial luminance uniformity, spatial color uniformity, angular luminance uniformity, angular luminous intensity uniformity in a region of at least one of the light guides or in a region of a surface or output of the light emitting region or light emitting device. In one embodiment, the width of the light mixing area is selected from the range of 0.1mm (for small displays) to greater than 10 feet (for large billboards). In one embodiment, the light-mixing region is a region disposed along the optical path near an end region of the coupling lightguides where light from two or more coupling lightguides can mix with each other and then propagate to the light-emitting region of the lightguide. In an embodiment, the light-mixing region is formed of the same composition or material as at least one of the light guide, the light guide region, the light input-coupler and the coupling light guide.

Width of array of mixing regions or coupling light guides

In one embodiment, the length of the array of coupling lightguides and/or light mixing regions is longer than the light emission region or lightguide region in a direction parallel to the array direction of the coupling lightguides (perpendicular to the extension direction of the array of coupling lightguides). In one embodiment, the array of coupling lightguides and/or light-mixing regions extends in a direction parallel to the array direction of the coupling lightguides (perpendicular to the extension direction of the coupling lightguides) over a distance of a lateral side of the light-emitting region: greater than 1 millimeter; greater than 2 mm; greater than 4 mm; greater than 6 mm; greater than 10 mm; greater than 15 mm; greater than 20 mm; greater than 50% of the average width of the coupling lightguides; greater than 100% of the average width of the coupling lightguides; and greater than 1%,2%,5% or 10% of the length of the light emitting area in a direction parallel to the alignment direction of the coupling lightguides. In one embodiment, the array of coupling lightguides or light mixing regions extends beyond the lateral edge of the light emitting region opposite the folding direction. In another embodiment, the array of coupling lightguides or light mixing regions extends beyond the lateral sides of the light emitting region in the folding direction. In one embodiment, more light can be introduced into the edge region (defined as within 10% of the lateral edge of the area of the light-emitting region) by extending the array of coupling lightguides past the lateral edge of the light-emitting region and/or extending the light-mixing region past the lateral edge of the light-emitting region. In another embodiment, a lateral edge of the light-mixing region, a lateral edge of one or more coupling lightguides, or an internal light-guiding edge, is oriented at a first extended orientation angle to the direction of extension of the coupling lightguides to direct light from an extended region or light-mixing region of the array of coupling lightguides toward a light-emitting region of the film-based lightguide. In one embodiment, the first extended orientation angle is greater than one selected from the group consisting of: 0 degrees, 2 degrees, 5 degrees, 10 degrees, 20 degrees, 30 degrees, 45 degrees, and 60 degrees. For example, in one embodiment, the array of coupling lightguides comprises coupling lightguides extending beyond the distal lateral edge of the light-emitting region (the edge furthest from the light source), and the light-mixing region comprises a lateral edge having an extended orientation angle of 30 degrees. In this embodiment the length of the remote coupling light guide is longer, so more light is absorbed by the material. One way to compensate for the difference in light flux to the distal edge region of the light emission region due to the longer path length of light propagating towards the distal edge region of the light emission region is to add an additional coupling lightguide that can receive the distributed portion of light from the light source and then direct it to the distal edge region of the light emission region by extending the angled lateral or internal light guiding edge of the coupling lightguide, the light mixing region, or both.

Housings or holding arrangements for optical input-couplers

In one embodiment, a light emitting apparatus includes a housing or holding device that holds or includes at least a portion of a light input coupler and a light source. The housing or holding means may contain or comprise at least one selected from the group consisting of: a light input coupler, a light source, a coupling light guide, a light guide, an optical component, an electrical component, a heat sink or other thermal component, an attachment mechanism, an alignment mechanism, a folding mechanism device, and a frame. The housing or holding means may comprise a plurality of components or any combination of the aforementioned components. The housing or holding means may serve one or more of the following functions: preventing contamination by dust and debris, providing an airtight seal, providing a watertight seal, containing or housing a component, providing a safety enclosure component for electrical or optical, assisting in folding or bending of a coupling lightguide, assisting in aligning or maintaining the position of a lightguide, a coupling lightguide, a light source or light input coupler relative to another component, maintaining the arrangement of coupling lightguides, recycling light (such as internal walls with reflectivity), providing an attachment mechanism for connecting a light emitting device to an external object or surface, providing an opaque receptacle so that stray light does not exit through a particular area, providing a translucent surface for displaying indicia or providing illumination for an object external to the light emitting device, including connectors for releasing and interchanging components, and providing latches or connectors that can be connected to other holding devices or enclosures.

In one embodiment, the housing or holding means comprises at least one selected from the group consisting of: connectors, pins, clips, latches, adhesive regions, clamps, attachment mechanisms, and other connecting or mechanical means of connecting or holding a housing to hold the housing or holding device to another housing or fixture, a light guide, a coupling light guide, a film, a strip, a cassette, one or more parts that are movable, an exterior surface (e.g., a window or an automobile), a light source, an electronic or electrical component, a circuit board for an electronic device or a light source such as an LED, a heat sink or other thermal control element, a frame of a light emitting device, and other parts of a light emitting device.

In another embodiment, the input end and the output end of the coupling light guide are held in physical contact with the relative position holding element by at least one selected from the group consisting of: magnetic grips, mechanical grips, clamps, screws, mechanical adhesion, chemical adhesion, dispersion adhesion, diffusion adhesion, electrostatic adhesion, vacuum holding power or adhesives.

Curved or flexible casings

In another embodiment, the housing includes at least one curved surface. Curved surfaces may allow the use of non-linear shapes or devices, or facilitate the incorporation of non-planar or curved light guides or coupling light guides. In one embodiment, a light emitting device includes a housing having at least one curved surface, where the housing includes a curved or bent coupling light guide. In another embodiment, the housing is flexible such that it can be temporarily, permanently or semi-permanently bent. For example, by using a flexible housing, the light emitting device may be bent such that the light emitting surface is curved together with the housing, e.g. the light emitting area may be curved around a bend in a wall or corner. In one embodiment, the housing or light guide may be temporarily bent such that the original shape is substantially restored (e.g., bending an elongated housing to pass through a door). In another embodiment, the housing or light guide may be permanently or semi-permanently bent such that the bent shape is substantially maintained after release (e.g., when it is desired to have a bent light emitting device to provide a bent sign or display).

Low contact area cover

In one embodiment, a low contact area cover is disposed between the at least one coupling light guide and the exterior of the light emitting device. The low contact area cover or wrap provides a low contact surface area in contact with the light guide or the region coupling the light guide, and may further provide at least one selected from the group consisting of: anti-fingerprint, anti-dust or air contamination, protection from moisture, protection from internal objects that may decouple or absorb more light than a low contact area cover when an internal or external object is in contact with one or more coupling lightguides in one or more areas, providing a means for holding or including at least one coupling lightguide, holding the relative position of one or more coupling lightguides, reflecting light back into the lightguide, and preventing the coupling lightguides from unfolding into a larger volume or contacting a surface that may decouple or absorb light.

Coating layer

In one embodiment, at least one of the light input-coupler, the coupling lightguide, the light mixing region, the lightguide region, and the lightguide comprises a cladding layer optically coupled to at least one surface. As used herein, a cladding region is a layer optically coupled to a surface, where the cladding layer comprises an index of refraction n _clad Refractive index n of a material smaller than a surface to which it is optically coupled _m The material of (1). In an embodiment, the average thickness of one or both cladding layers of the light guide is less than one selected from the group consisting of: 100 microns, 60 microns, 30 microns, 20 microns, 10 microns, 6 microns, 4 microns, 2 microns, 1 micron, 0.8 microns, 0.5 microns, 0.3 microns, and 0.1 microns. In one embodiment, the cladding layer includes an adhesive, such as a silicon-based adhesive, an acrylate-based adhesive, an epoxy, a radiation-curable adhesive, a UV-curable adhesive, or other light-transmissive adhesive. Fluoropolymer materials may be used as the low index cladding material. In one embodiment, the cladding region is optically coupled to one or more of: a light guide, a light guide region, a light mixing region, one surface of the light guide, two surfaces of the light guide, a light input coupler, a coupling light guide, and an outer surface of the film. In another embodiment, the package is packagedThe cladding layer is disposed in optical contact with the light guide, the light guide region, or one or more layers optically coupled to the light guide, and the cladding material is not disposed on the one or more coupling light guides.

In one embodiment, the coating layer is one selected from the group consisting of: methyl-based silicone pressure sensitive adhesives, fluoropolymer materials (applied using a coating comprising a fluoropolymer substantially dissolved in a solvent), and fluoropolymer films. The cladding layer may be incorporated to provide a separating layer between the core or core portion of the lightguide region and the outer surface to reduce unwanted out-coupling from the core or core portion region of the lightguide region (e.g., frustrating total internal reflection light by contacting the film with an oily finger). Components or objects that are in direct or optical contact with the core or core region of the light guide, such as additional films, layers, objects, fingers, dust, etc., may couple light out of the light guide, absorb light, or transfer totally internally reflected light into a new layer. By adding a cladding layer with a lower refractive index than the core, a portion of the light will be totally internally reflected at the core-cladding layer interface. The cladding layer may also be used to provide at least one of the following advantages: increased stiffness, increased flexural modulus, increased impact resistance, antiglare properties, providing an intermediate layer to combine with other layers, such as a tie layer or substrate which in the case of the function of a cladding layer is an antireflective coating, a substrate for an optical component, such as a polarizer, a liquid crystal material, increased scratch resistance, providing other functions (e.g. low tack adhesive for bonding a lightguide region to another component, window "cling" films, such as highly plasticized PVC). The cladding layer may be an adhesive, such as a low index silicone adhesive, that is optically coupled to another element of the device, the light guide region, the light mixing region, the light input coupler, or a combination of one or more. In one embodiment, the cladding layer is optically coupled to a rear polarizer in a backlit liquid crystal display. In another embodiment, the cladding layer is optically coupled to a polarizer or a front-lit display, such as an electrophoretic display, an electronic book display, an electronic reader display, a MEMs type display, an electronic paper display, such as the E-Ink display of E Ink corporation, a reflective or partially reflective LCD display, a cholesteric display, or other display capable of being illuminated from the front. In another embodiment, the cladding layer is an adhesive that bonds the lightguide or lightguide region to an element such as a substrate (glass or polymer), an optical element (such as a polarizer, a retardation film, a diffuser film, a brightness enhancement film, a protective film (e.g., a protective polycarbonate film)), a light input coupler, a coupling lightguide or other element of a light emitting device, and the like. In one embodiment, the cladding layer is separated from the light guide or the core layer of the light guide region by at least one additional layer or adhesive.

In one embodiment, the cladding regions are optically coupled to one or more surfaces of the light mixing region to prevent light from being outcoupled from the light guide when the light guide is in contact with another component. In this embodiment, the cladding layer also enables the cladding layer and the light mixing region to be physically coupled to another component.

Position of the cladding layer

In one embodiment, the cladding region is optically coupled to at least one selected from the group consisting of: a light guide, a light guide region, a light mixing region, one surface of the light guide, two surfaces of the light guide, a light input coupler, a coupling light guide, and an outer surface of the film. In another embodiment, the cladding layer is disposed in optical contact with the light guide, the light guide region, or one or more layers optically coupled to the light guide, and no cladding material is disposed on the one or more coupling light guides. In one embodiment, the coupling lightguides do not include cladding layers between core regions in the region proximate the light input surface or light source. In another embodiment, the core regions may be pressed together or held together after stacking or assembly, and the edges may be cut and/or polished to form a light input surface or light turning edge that is flat, curved, or a combination thereof. In another embodiment, the cladding layer is a pressure sensitive adhesive, and a release liner for the pressure sensitive adhesive is selectively removed in areas of one or more of the coupling lightguides that are stacked or aligned together in an array, such that the cladding layer helps to maintain the position of the coupling lightguides relative to each other. In another embodiment, the protective liner is removed from the inner cladding region of the coupling light guide and left on one or both outer surfaces of the out-coupling light guide.

In one embodiment, the cladding layer is disposed on one or both opposing surfaces of the light emitting region and is not disposed between two or more coupling lightguides at the light input surface. For example, in one embodiment, a masking layer is applied to the film-based light guide corresponding to the end region of the coupling light guide that will form the light input surface (and possibly the coupling light guide) after cutting, and a low-index coating is applied to one or both sides of the film. In this embodiment, when the mask is removed and the coupling lightguides are folded (e.g., using relative position-retaining elements) and stacked, the light input surface may include a core layer without a cladding layer, and the light emitting region may include a cladding layer (and the light mixing region may also include a cladding layer and/or a light absorbing region), which may be advantageous for optical efficiency (light is directed into the cladding layer at the input surface) and in applications such as reflective or reflective film-based front light applications where a cladding layer may be required in the light emitting region.

In another embodiment, the protective lining of at least one outer surface of the outcoupling light guide is removed, so that the stack of coupling light guides can be bonded to one of: a circuit board, an unfolded coupling light guide, a collimating optical element, a light turning optical element, a light coupling optical element, a flexible connector or substrate for a display or touch screen, a second array of stacked coupling light guides, a light input coupler housing, a light emitting device housing, a heat transfer element, a heat sink, a light source, an alignment guide or component including a window for a light input surface, and any suitable element disposed on and/or physically coupled to a light input surface or an element of a light emitting device. In one embodiment, none of the coupling lightguides includes a cladding region on a planar side, and optical losses at bends or folds in the coupling lightguides are reduced. In another embodiment, the coupling lightguide does not include a cladding region on either planar side and the light input surface in-coupling efficiency is improved due to the light input surface area having a higher concentration of the lightguide receiving surface relative to a lightguide with at least one cladding layer.

In one embodiment, a cladding layer is applied (e.g., coated or co-extruded) on at least one surface of the light guide, and the cladding layer on the coupling light guide is subsequently removed. In another embodiment, the cladding layer applied on the surface of the light guide (or the light guide applied on the surface of the cladding layer) is such that the region corresponding to the coupling light guide is free of the cladding layer. For example, the cladding material may be extruded or coated onto the light guide film in the central region, where the outside of the film will include the coupling light guide. Similarly, there may be no cladding layer on the coupling lightguides in the areas disposed proximate to the one or more light sources or the light input surface.

In one embodiment, the two or more core regions of the coupling lightguides are disposed at less than one distance selected from the group consisting of: the cladding regions were excluded between the core regions in the region of the coupling lightguides 1 mm, 2 mm, 4 mm, 8 mm from the edge of the light input surface of the coupling lightguides. In another embodiment, the two or more core regions of the coupling lightguide are disposed at less than one distance selected from the group consisting of: the cladding regions are excluded between core regions in regions of the coupling lightguides that are spaced 10%,20%,50%,100%,200%, and 300% of the combined thickness of the cores of the coupling lightguides that receive light from the light source from the light input surface edge of the coupling lightguides. In one embodiment, the coupling lightguides in the region near the light input surface do not include cladding layers between the core regions (but may include cladding layers on the outer surfaces of the collection of coupling lightguides), and the coupling lightguides are optically coupled together with an index-matching adhesive or material, or the coupling lightguides are optically bonded, fused, or thermo-mechanically welded together by the application of heat and pressure. In another embodiment, the light source is at a distance from the light input surface of the coupling light guide that is less than one selected from the group consisting of: 0.5 mm, 1 mm, 2 mm, 4 mm and 6 mm, and a dimension of the light input surface in a first direction parallel to a thickness direction of the coupling light guide is larger than one selected from the group of: the light emitting surface of the light source has a dimension in the first direction of 100%,110%,120%,130%,150%,180%, and 200%. In another embodiment, an index matching material is disposed between the core regions of the coupling lightguide or the coupling lightguides are optically coupled or joined together in a region proximate the light source, the light optically coupled into the coupling lightguide being more than the light coupler with the cladding region extending substantially to the light input edge of the coupling lightguide by at least one selected from the group consisting of: 10%,20%, 30%,40% and 50%. In one embodiment, the index of refraction of the index-matching binder or material differs from the core region by less than 0.1, 0.08, 0.05, and 0.02. In another embodiment, the index-matching adhesive or material has an index of refraction greater than the core region by less than one selected from the group consisting of 0.1, 0.08, 0.05, and 0.02. In another embodiment, cladding regions are disposed between the core regions of the first set of coupling lightguides for the second set of coupling lightguides, index matching regions are disposed between the core regions of the coupling lightguides, or they are fused together. In a further embodiment, a coupling lightguide arranged to receive light from a geometric center of a light emitting region of a light source within a first angle of the optical axis of the light source has cladding regions arranged between core regions, and the core regions at angles greater than the first angle provide index matching regions between or blend together the core regions of the coupling lightguide. In one embodiment, the first angle is selected from the group of: 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees and 60 degrees. In the foregoing embodiments, the cladding region may be a low refractive index material or air. In another embodiment, the total thickness of the coupling lightguides in the area arranged to receive light from a light source to be coupled into the coupling lightguides is less than n times the thickness of the lightguide area, where n is the number of coupling lightguides. In another embodiment, the total thickness of the coupling light guide in the area arranged to receive light from the light source to be coupled into the coupling light guide is substantially equal to n times the thickness of the light guide layer within the light guide area.

Thickness of clad layer

In one embodiment, the average thickness of one or both cladding layers of the light guide is less than one selected from the group consisting of: 100 microns, 60 microns, 30 microns, 20 microns, 10 microns, 6 microns, 4 microns, 2 microns, 1 micron, 0.8 microns, 0.5 microns, 0.3 microns, and 0.1 microns.

Under total internal reflection conditions, evanescent wave light penetrates from a denser region to a sparser medium at a depth λ e from an interface where the amplitude of the light in the sparser medium is 1/e of the amplitude at the boundary, given by the equation:

where λ 0 is the wavelength of light in vacuum, ns is the refractive index of the denser medium (core region), ne is the refractive index of the sparse medium (cladding layer), and θ i is the angle of incidence to the interface in the dense medium. The equation for penetration depth indicates that for many ranges of angles above the critical angle, light propagating within the light guide does not require very thick cladding layer thicknesses to maintain the light guide conditions. For example, light propagating within a visible wavelength range of 400 nanometers to 700 nanometers in a core region of a silicone film having a refractive index of 1.47 of a fluoropolymer clad material having a refractive index of 1.33 has a critical angle at about 65 degrees, and light propagating between 70 degrees and 90 degrees has a 1/e penetration depth λ e of less than about 0.3 microns. In this example, the cladding region may be about 0.3 microns thick, and the light guide will significantly maintain transmission of visible light under light guide conditions from the interface normal to between about 70 and 90 degrees. In another embodiment, the ratio of the thicknesses of the core layer and the one or more cladding layers is greater than one selected from the group consisting of: 2. 4, 6, 8, 10, 20, 30, 40, and 60 to 1. In one embodiment, a high core-to-cladding layer thickness ratio, with the cladding layer extending over the light emission region and the coupling light guide, allows more light to be coupled into the core layer at the light input surface because the cladding region occupies a lower percentage of the area of the light input surface.

In one embodiment, the cover layer includes an adhesive, such as a silicone-based adhesive, an acrylate-based adhesive, an epoxy, a radiation-curable adhesive, a UV-curable adhesive, or other light-transmissive adhesive.

Covering material

Fluoropolymer materials can be used as low index cladding materials and can be broadly classified in one of two basic categories. The first class includes those amorphous fluoropolymers comprising interpolymerized units derived from vinylidene fluoride (VDF) and Hexafluoropropylene (HFP) and, optionally, tetrafluoroethylene (TFE) monomers. Examples of this are Dyneon ^TM Fluoroelastomers FC2145 and FT2430 are commercially available from 3M company. Another amorphous fluoropolymer that may be used in embodiments is, for example, VDF-chlorotrifluoroethylene copolymer. One such VDF-chlorotrifluoroethylene copolymer is commercially known as Kel-F ^TM 3700, commercially available from 3M company. As used herein, an amorphous fluoropolymer is a material that contains substantially no crystallinity or does not have a significant melting point, as determined, for example, by Differential Scanning Calorimetry (DSC). For the purposes of this discussion, a copolymer is defined as a polymeric material resulting from the simultaneous polymerization of two or more different monomers, and a homopolymer is a polymeric material resulting from the polymerization of a single monomer.

A second broad class of fluoropolymers useful in one embodiment are homopolymers and copolymers based on fluorinated monomers such as TFE or VDF having crystalline melting points, such as polyvinylidene fluoride (PVDF, available as Dyneon from 3M company ^TM Commercially available in the form of PVDF, or more preferably TFE thermoplastic copolymers such as those based on the crystalline microstructure of TFE-HFP-VDF. Examples of such polymers are those available under the trade name Dyneon from 3M ^TM FluoroplasticsTHV ^TM 200 parts of a commercially available polymer.

In one embodiment, the cladding material is birefringent and has a refractive index in at least a first direction that is less than the refractive index of the light guiding region, the light guiding core, or a material optically coupled thereto.

The intensity of collimated light propagating through a material may be reduced due to scattering (scattering loss factor), absorption (absorption factor) or a combination of scattering and absorption (attenuation factor). In one embodiment of the present invention,the cladding layer comprises a material having an average absorption coefficient for aligned direct light in the visible wavelength range from 400 nm to 700 nm that is less than one selected from the group consisting of: 0.03cm ^-1 、0.02cm ^-1 、0.01cm ^-1 And 0.005cm ^-1 . In another embodiment, the cladding layer comprises an average scattering loss coefficient of less than 0.03cm selected for aligning direct light over a spectral range of visible wavelengths from 400 nm to 700 nm ^-1 、0.02cm ^-1 、0.01cm ^-1 And 0.005cm ^-1 A material of one of (1). In another embodiment, the cladding layer comprises a material having an average attenuation coefficient less than from 0.03cm aligned with straight light over the visible wavelength spectrum from 400 nm to 700 nm ^-1 、0.02cm ^-1 、0.01cm ^-1 And 0.005cm ^-1 A selected one of them.

In another embodiment, the light guide includes a hard cladding layer that substantially protects a soft core layer (e.g., soft silicone or silicone elastomer).

In one embodiment, a light guide comprises: a core material having a Shore A hardness (JIS) of less than 50; and at least one coating layer having a Shore A hardness (JIS) of more than 50. In one embodiment, a lightguide includes a core material having a Young's modulus at 25 degrees Celsius of ASTM D638-10 of less than 2MPa and at least one cladding layer having a Young's modulus at 25 degrees Celsius of greater than 2MPa in ASTM D638-10. In another embodiment, a lightguide includes a core material having a Young's modulus at 25 degrees Celsius of ASTM D638-10 of less than 1.5MPa and at least one cladding layer having a Young's modulus at 25 degrees Celsius of greater than 2MPa with ASTM D638-10. In another embodiment, a lightguide includes a core material having a Young's modulus at 25 degrees Celsius of ASTM D638-10 of less than 1MPa and at least one cladding layer having a Young's modulus at 25 degrees Celsius of greater than 2MPa with ASTM D638-10.

In one embodiment, a lightguide includes a core material having an ASTM D638-10 Young's modulus at 25 degrees Celsius of less than 2MPa, and a lightguide film having an ASTM D638-10 Young's modulus at 25 degrees Celsius of greater than 2 MPa. In another embodiment, a lightguide includes a core material having a Young's modulus at 25 degrees Celsius of ASTM D638-10 of less than 1.5MPa and a lightguide film having a Young's modulus at 25 degrees Celsius of greater than 2MPa according to ASTM D638-10. In one embodiment, the lightguide includes a core material having a Young's modulus at 25 degrees Celsius of less than 1MPa in ASTM D638-10, and a lightguide film having a Young's modulus of greater than 2MPa in ASTM D638-10.

In another embodiment, the cladding layer comprises a material having an effective refractive index less than that of the core layer due to the micro-or nanostructures. In another embodiment, the cladding layer includes a porous region comprising air or other gas or material having an index of refraction less than 1.2 such that the effective index of refraction of the cladding layer is greater than the effective index of refraction of the material surrounding the porous region. For example, in one embodiment, the cladding layer is an arrangement of aerogel or nanostructured material disposed on the core layer, which forms a cladding layer having an effective refractive index less than the core layer. In one embodiment, the nanostructured material comprises fibers, particles or domains having an average diameter or size in a plane parallel to or perpendicular to the surface of the core layer that is less than one selected from the group consisting of: 1000. 500, 300, 200, 100, 50, 20, 10, 5, and 2 nanometers. For example, in one embodiment, the cladding layer is a coating comprising nanostructured fibers comprising a polymeric material such as, but not limited to, cellulose, polyester, PVC, PTFE, polystyrene, PMMA, PDMS, or other light transmissive or partially light transmissive material. In another embodiment, materials that would normally scatter too much light in bulk (e.g., HDPE or polypropylene) are used as the core or cladding layer for light guides greater than 1 meter in length (e.g., greater than 10% of the light scattered out of the light guide over a 1 meter length) in the form of nanostructures. For example, in one embodiment, when formed into a bulk solid form, the nanostructure clad material on a thin film-based light guide (e.g., a 200 micron thick homogeneous film formation without mechanically forming physical structures on the volume or surface under designed film processing conditions to substantially minimize haze) has an ASTM haze of greater than 0.5%.

In another embodiment, the microstructured or nanostructured cladding material includes structures that "wet-out" or optically couple light to light extraction features disposed in physical contact with the microstructured or nanostructured cladding material. For example, in one embodiment, the light extraction features comprise nanostructured surface features that couple light from the cladding regions when in close proximity or contact with the nanostructured cladding regions. In one embodiment, the microstructured or nanostructured cladding material has complementary structures to the light extraction features, such as male and female portions or other simple or complex complementary structures, such that the effective refractive index in the region including both structures is greater than the cladding region without the light extraction features.

Layers or regions on both sides of a light guide of higher and lower refractive index materials

In one embodiment, the light emitting region of the film-based light guide comprises: a first layer or coating of a first material having a first index of refraction optically coupled to a first surface of the thin film-based light guide in the light-emitting region. A second layer or coating of a second material having a second index of refraction optically coupled to an opposing surface of the film-based light guide in the light-emitting region, the second index of refraction being higher than the first index of refraction, the second index of refraction and the first index of refraction being less than the index of refraction of the material in the core region of the light guide. In this embodiment, light propagating within the core layer or region of the thin film light guide in the light emission region undergoing low angle light redirection will preferentially leak or exit the light guide from the sides having the second index of refraction, for example, through the low angle guiding features, since the second index of refraction is higher than the first index of refraction and the critical angle is higher. In this embodiment, light that deviates from angles above the critical angle to smaller angles in the thickness direction of the film will first pass through the total internal reflection interface on the side of the core layer or region that is optically coupled to the cladding layer or region with a higher refractive index.

Light guide configuration and Properties

In one embodiment, the thickness of the film, light redirecting optical element, reflective display, lightguide and/or lightguide region is in the range of 0.005mm to 0.5mm. In another embodiment, the film or light guide has a thickness in the range of 0.025mm (0.001 inch) to 0.5mm (0.02 inch). In another embodiment, the thickness of the film, light guide and/or light guide region is in the range of 0.050mm to 0.175 mm. In one embodiment, the thickness of the film, light guide or light guide region is less than 0.2mm or less than 0.5mm. In one embodiment, one or more of the thickness, maximum thickness, average thickness, and overall thickness greater than 90% of the film, light guide, and light guide regions are less than 0.2 millimeters.

Optical characteristics of light guides or light transmissive materials

With respect to the optical properties of the light guides, light redirecting optical elements or regions, light extraction films or regions, or light transmissive materials of certain embodiments, the optical properties specified herein may be general properties of the light guide, core, cladding layer, or combinations thereof, or they may correspond to particular regions (e.g., light emitting regions, light mixing regions, or light extraction regions), surfaces (light input surfaces, diffusing surfaces, planar surfaces), and directions (e.g., measured perpendicular to the surface or along the direction of light through the light guide).

Refractive index of light transmissive material

In one embodiment, the core material of the light guide has a higher refractive index than the cladding material. In one embodiment, the core is composed of a refractive index (n) _D ) Material formation of greater than one selected from the group of: 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4,2.5, 2.6, 2.7, 2.8, 2.9 and 3.0. In another embodiment, the refractive index (n) of the cladding material _D ) Less than one selected from the group consisting of: 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4 and 2.5.

Edge of light guide

In one embodiment, the edges of the light guide or light guide regions are coated, bonded to or disposed adjacent to the specular, partially diffuse, or diffuse reflective material. In one embodiment, the edges of the light guide are coated with a specularly reflective ink comprising nano-sized or micro-sized particles or flakes that substantially specularly reflect light. In another embodiment, a light reflecting element (e.g., a specularly reflective multilayer polymer film having a high reflectivity) is disposed near the edge of the light guide and is configured to receive light from the edge and reflect it and direct it back into the light guide. In another embodiment, the light guide edges are rounded and the percentage of light diffracted from the edges is reduced. One way to achieve rounded edges is by cutting the light guide from the film using a laser and by controlling the processing parameters (cutting speed, cutting frequency, laser power, etc.) to achieve edge rounding. In another embodiment, the edges of the light guide are tapered, angled serrated, or otherwise cut or formed such that light from the light source propagates within the coupling light guide, reflects from the edges, and is directed to an angle closer to the optical axis, with the light source facing the fold region, facing the bend region, facing the light guide region, or facing the optical axis of the light emitting device. In another embodiment, two or more light sources are provided, each coupling light into two or more coupling light guides, the two or more coupling light guides comprising a light redirecting area for each of the two or more light sources, the light redirecting area comprising first and second reflective surfaces that direct a portion of the light from the light sources to an angle closer to the optical axis of the light sources, toward the fold or bend area, toward the light guide area, or toward the optical axis of the light emitting device. In one embodiment, one or more edges of the coupling light guide, light mixing region, or light guide region include a curved or arced profile in an intersection region between two or more surfaces of the film in that region.

Shape of light guide

In one embodiment, the light guide shape or at least a portion of the light guide surface is substantially planar, curved, cylindrical, shaped by a substantially planar film, spherical, partially spherical, angled, twisted, circular, having a quadratic surface, spherical, cuboid, parallelepiped, triangular prismatic, rectangular prismatic, elliptical, oval, pyramidal, wavy, and/or other known suitable geometric entity or shape. In one embodiment, the light guide is a film formed into a shape by thermoforming or other suitable forming techniques. In another embodiment, the film or region of the film is tapered in at least one direction. In another embodiment, a light emitting device includes a plurality of light guides and a plurality of light sources (e.g., tiled in a 1x2 array) physically coupled or disposed together. In another embodiment, the surface shape of the light guiding region of the film is substantially polygonal, triangular, rectangular, square, trapezoidal, diamond, oval, circular, semicircular, segments or sectors of a circle, crescent, oval, ring, alphanumeric character shape (e.g., "U-shaped" or "T-shaped"), or a combination of one or more of the foregoing shapes. In another embodiment, the shape of the light-guiding region of the film is substantially a polyhedron, annular polyhedron, curved polyhedron, spherical polyhedron, rectangular cuboid, cube, orthocube, star, prism, pyramid, cylinder, cone, frustoconical, ellipsoid, paraboloid, hyperboloid, sphere, or a combination of one or more of the foregoing shapes.

Thickness of the light guide

In one embodiment, the thickness of the film, lightguide region and/or light emitting region is in the range of 0.005mm to 0.5mm. In another embodiment, the film or light guide has a thickness in the range of 0.025mm (0.001 inch) to 0.5mm (0.02 inch). In another embodiment, the thickness of the film, light guide and/or light guide region is in the range of 0.050mm to 0.175 mm. In one embodiment, the thickness of the film, light guide or light guide region is less than 0.2mm or less than 0.5mm. In one embodiment, one or more of the thickness, the maximum thickness, the average thickness, and the thickness greater than 90% of the entire thickness of the film, the light guide, and the light guide region are less than 0.2 millimeters. In an embodiment, the spacing between the two surfaces of the core layer of the light guide or the region of the light guide in the light emission region deviates from the average spacing by less than one of the group of 30%,20%,10% and 5%. In another embodiment, the separation distance between the two surfaces defining the total internal reflection surface of the light guide within the light emission area deviates from the average separation distance by less than one of the group of 30%,20%,10% and 5% of the average separation distance. In one embodiment, the average angle between two surfaces defining the total internal reflection surface of the light guide within the light emission area is less than one selected from the group consisting of 10, 8, 6, 5, 4, 3, 2, 1 and 0.5 degrees.

In one embodiment, the light emitting region tapers along the direction of propagation of light within the core region or layer of the light guide in the light emitting region from a first thickness at a first side of the light emitting region that receives light from the light mixing region and/or the light input coupler to a second thickness less than the first thickness at an opposite side of the light emitting region. In one embodiment, the average angle of taper, the average angle between two opposing layer surfaces or regions of the core layer of the light guide from the first side to the second side, is less than one selected from the group of 10, 8, 6, 5, 4, 3, 2, 1, and 0.5 degrees.

In another embodiment, the light-emitting region includes one or more regions or layers optically coupled to a core region of the film-based light guide that increase the effective thickness of the light guide defined by interfaces that define total internal reflection of light propagating in the light-emitting region from a first end of the light guide to an opposite end. In another embodiment, a ratio of an average thickness of the light-emitting region defined by the interface defining total internal reflection of light propagating from the first end to the opposite end of the light-emitting region to an average thickness of the light-mixing region is greater than or equal to one or more of: 1. 2, 5, 10, 15, 20, 25, 30, 40 and 50. In another embodiment, the light-emitting region comprises one or more regions or layers optically coupled to the core region of the thin-film based light guide that increase the effective thickness of the light guide defined by the interface that defines total internal reflection of light propagating from a first end of the light-emitting region to an opposite end.

In another embodiment, a light emitting device (e.g., for reflecting front light of a display) includes a film-based light guide, where a surface of the film defines a first light guide, and the first light guide is optically coupled to a light redirecting optical element or other film, and one or more surfaces of the light redirecting optical element or other film in combination with the surface of the first light guide define a second light guide, where the second light guide may include the first light guide. In this embodiment, the ratio of the average thickness of the light-emitting region defined by the interface defining total internal reflection of light propagating from the first end to the other end of the light-emitting region of the second light guide or the first light guide to the average thickness of the mixing region or the film is greater than or equal to one or more selected from the group consisting of: 1. 2, 5, 10, 15, 20, 25, 30, 40 and 50. In another embodiment, the ratio of the largest dimension of the light emission area of the first or second light guide in a plane orthogonal to the thickness direction of the light emission surface or an area of the light emission surface (parallel to the surface of the core layer) to the average thickness of the first or second light guide in the light emission area is greater than one or more selected from the group consisting of: 1. 2, 5, 10, 15, 20, 25, 30, 40, 50.100, 200, 300, 500, 700, 1000, and 2000.

In one embodiment, a reflective display includes a lightguide in which total internal reflection light within a core layer is frustrated by a plurality of light extraction features, increasing an effective thickness of the lightguide bounded by total internal reflection interfaces such that it passes through a first cladding layer and is totally internally reflected at one of the total internal reflection interfaces of a light redirecting optical element. In another embodiment, a light emitting apparatus includes: a first light guide having a core layer with a thickness between opposing surfaces of the core layer of no greater than about 0.5 millimeters; a first light guide defined by the opposing surface to guide light by total internal reflection; and a second light guide comprising the core layer, the second light guide defined by a second portion of the first light guide that is frustrated total internal reflection light that propagates by total internal reflection between a surface of the first light guide and a surface area of the light redirecting optical element between the light redirecting features. In another embodiment, a light guide includes a first light guide and a second light guide including a core layer, the second light guide defined by a portion of frustrated total internal reflection light from the first light guide that propagates by total internal reflection between a surface of the first light guide and a surface area of a light redirecting optical element. Wherein the light redirecting features of the light redirecting optical element occupy less than 50% of the surface of the light redirecting optical element, the surface area of the light redirecting element being defined between the light redirecting features and reflecting by total internal reflection a second portion of the frustrated total internal reflection light from the light extraction features back, through the first cladding layer and into the core layer, which reflects from the surface of the first light guide and is subsequently reflected by the light redirecting features towards the reflective spatial light modulator.

Light guide material

In one embodiment, a light emitting device includes a light guide or light guide region formed from at least one light transmissive material. In one embodiment, the light guide is a film comprising at least one core region and at least one cladding region, each core region and at least one cladding region comprising at least one light transmissive material. In one embodiment, the light transmissive material is a thermoplastic, thermoset, rubber, polymer, high transmission silicone, glass, composite, alloy, blend, silicone or other suitable light transmissive material or combination thereof. In one embodiment, the components or regions of the light emitting device comprise a suitable light transmissive material, such as one or more of the following: cellulose derivatives (for example, cellulose ethers such AS ethyl cellulose and cyanoethyl cellulose, cellulose esters such AS cellulose acetate), acrylic resins, styrene resins such AS polystyrene, resins of the polyethylene series [ for example, poly (vinyl esters) such AS polyvinyl acetate, poly (vinyl halides) such AS poly (vinyl chloride), polyvinyl alkyl ethers or polyether-series resins such AS poly (vinyl methyl ether), poly (vinyl isobutyl ether) and poly (vinyl t-butyl ether) ], resins of the polycarbonate series (for example, aromatic polycarbonates such AS bisphenol A type polycarbonate), resins of the polyester series (for example, homopolyesters such AS polyalkylene terephthalate such AS polyethylene terephthalate and polybutylene terephthalate, polyalkylene naphthalate corresponding to polyalkylene terephthalate; comprising alkylene terephthalate and/or alkylene naphthalate AS a main component; homopolymers of lactones such AS polycaprolactone), resins of the polyamide series (for example, nylon 6, nylon 66, nylon 610), resins of the urethane series (for example, thermoplastic polyurethane resins), copolymers of monomers forming the above resins [ for example, styrene copolymers and the like [ for example, AS methyl methacrylate copolymers ], styrene-acrylonitrile-styrene copolymers (AS styrene-co-copolymers), acrylonitrile-styrene copolymers (AS styrene copolymers, acrylonitrile-co-styrene copolymers (AS styrene copolymers), vinyl acetate-vinyl chloride copolymer, vinyl alkyl ether-maleic anhydride copolymer. Incidentally, the copolymer may be any of a random copolymer, a block copolymer or a graft copolymer.

Light guide material with adhesive properties

In another embodiment, the light guide comprises a material having at least one selected from the group consisting of: chemical adhesion, dispersion adhesion, electrostatic adhesion, diffusion adhesion, and mechanical adhesion to at least one element of the light-emitting device (e.g., a coated carrier film, an optical film, a rear polarizer in an LCD, a brightness enhancement film, another region of a light guide, a coupling light guide, a heat transfer element, such as an aluminum-containing foil or a white reflective film). In another embodiment, at least one of the core material or the cladding material of the light guide is an adhesive material. In another embodiment, at least one selected from the group consisting of: the core material, the cladding material and the material provided on the cladding material of the light guide are at least one selected from the group consisting of: pressure sensitive adhesives, contact adhesives, hot glues, adhesives, dry adhesives, multi-part reactive adhesives, one-part reactive adhesives, natural adhesives, and synthetic adhesives. In another embodiment, the first core material of the first coupling light guide is adhered to the second core material of the second coupling light guide due to the adhesive properties of the first core material, the second core material, or a combination thereof. In another embodiment, the cladding material of the first coupling light guide is adhered to the core material of the second coupling light guide due to the adhesive properties of the cladding material. In another embodiment, the first cladding material of the first coupling light guide adheres to the second cladding material of the second coupling light guide due to the adhesive properties of the first cladding material, the second cladding material, or a combination thereof. In one embodiment, the core layer is an adhesive and is coated on at least one selected from the group consisting of: a cladding layer, a removable support layer, a protective film, a second adhesive layer, a polymer film, a metal film, a second core layer, a low contact area cap, and a planarization layer. In another embodiment, the cladding or core material has adhesive properties and, when adhered to a component of a light emitting device, such as but not limited to a cladding layer, a core layer, a low contact area cap, a circuit board or a housing, has an ASTM D3330 peel strength greater than one selected from the group consisting of: 8.929, 17.858, 35.716, 53.574, 71.432, 89.29, 107.148, 125.006, 142.864, 160.722, 178.580 kg/m combined width.

In another embodiment, a tie layer, primer or coating is used to promote adhesion between at least one selected from the group consisting of: core materials and cladding materials, light guides and housings, core materials and components for light emitting devices, cladding materials and components for light emitting devices. In one embodiment, the tie layer or coating comprises dimethylsiloxane or a variant thereof and a solvent. In another embodiment, the bonding layer comprises a phenyl-based primer, such as a primer for bridging a phenylsiloxane-based silicone with the substrate material. In another embodiment, the tie layer comprises a platinum catalyzed addition cure silicone primer, such as a primer for bonding a plastic film substrate and a silicone pressure sensitive adhesive.

In another embodiment, at least one region of the core or cladding material has adhesive properties and is optically coupled to a second region of the core or cladding material such that the ASTM D1003 light transmission through the interface is at least one selected from the group consisting of: the amount of transmission is 1%,2%,3% and 4% greater than in the case where the same two materials are passed through the same region with an air gap provided therebetween.

In one embodiment, the core material of the light guide comprises a material having a critical surface tension less than that selected from the group consisting of: 33. 32, 30, 27, 25, 24 and 20mN/m. In another embodiment, the core material has a critical surface tension less than one selected from the group consisting of: 33. 30, 27, 25, 24 and 20mN/m and is surface treated to increase the critical surface tension to more than one selected from the group consisting of: 27. 30, 33, 35, 37, 40 and 50. In one embodiment, the surface treatment comprises exposing the surface to at least one selected from the group consisting of: plasma, flame and bond coat materials. In one embodiment, the surface tension of the core material of the light guide is reduced to reduce light extraction from the contacted surfaces due to "wetting out" and optical coupling. In another embodiment, the surface tension of the surface of the light guide

Multilayer light guide

In one embodiment, the light guide comprises at least two layers or coatings. In another embodiment, the layer or coating serves as at least one selected from the group consisting of: core layers, cladding layers, tie layers (to promote adhesion between the other two layers), layers to increase flexural strength, layer impact strength (e.g., izod, charpy, gardner) to increase layers, and carrier layers. In another embodiment, at least one layer or coating includes microstructures, surface relief patterns, light extraction features, lenses or other non-planar surface features that redirect a portion of incident light from within the light guide to an angle such that the light exits the light guide in a region near the feature. For example, the carrier film may be a silicone film with embossed light extraction features arranged to receive a thermoset polycarbonate resin core region comprising a thermoset material.

In one embodiment, the thermoset material is coated onto the thermoplastic film, wherein the thermoset material is the core material and the cover material is the thermoplastic film or material. In another embodiment, a first thermoset material is coated onto a film comprising a second thermoset material, wherein the first thermoset material is a core material and the cover material is a second thermoset.

Light extraction method

In one embodiment, one or more of the lightguide, lightguide region, and light emitting region includes at least one light extraction feature or region. In an embodiment, the light extraction regions may be raised or recessed surface patterns or volumetric regions. Raised and recessed surface patterns include, but are not limited to, scattering materials, raised lenses, scattering surfaces, pits, grooves, surface modulations, microlenses, lenses, diffractive surface features, holographic surface features, photonic band gap features, wavelength conversion materials, holes, edges, or layers (e.g., regions where cladding layers are removed from overlying core layers), pyramidal shapes, prismatic shapes, and other geometric shapes having flat surfaces, curved surfaces, random surfaces, quasi-random surfaces, and combinations thereof. The bulk scattering region within the light extraction region may include dispersed phase domains, voids, the absence of other materials or regions (gaps, voids), air gaps, boundaries between layers and regions and other refractive index discontinuities or inhomogeneities within its volume other than a coplanar layer with parallel interface surfaces.

In one embodiment, the light extraction features are substantially directional and include one or more of: angled surface features, curved surface features, rough surface features, random surface features, asymmetric surface features, scribed surface features, cut surface features, non-planar surface features, stamped surface features, molded surface features, compression molded surface features, thermoformed surface features, milled surface features, extruded mixtures, blended materials, material alloys, composites of symmetrically or asymmetrically shaped materials, laser ablated surface features, embossed surface features, coated surface features, injection molded surface features, extruded surface features, and one of the above features disposed in a light guide volume. For example, in one embodiment, the directional light extraction features are 100 micron long, 45 degree angled facet grooves formed by UV curing an embossed coating on a light guide film that substantially directs a portion of the incident light within the light guide toward a direction at 0 degrees from the light guide surface normal.

In one embodiment, the light extraction features are reflective materials that are specular, diffuse, or a combination thereof. For example, the light extraction features may be a substantially specularly reflective ink disposed at an angle (e.g., coated onto the grooves), or the light extraction features may be a substantially diffusely reflective ink, such as an ink including titanium dioxide particles in a methacrylate agent-based binder. In one embodiment, a thin lightguide film allows smaller features to be used for the light extraction features, or the light extraction surface features are spaced further apart due to the thinness of the lightguide. In one embodiment, the average maximum dimension of the light extraction surface features in a plane parallel to the light emission surface corresponding to the light emission area of the light emitting device is less than one of 3mm,2mm,1mm,0.5mm,0.25mm,0.1mm, 0.080, 0.050mm,0.040mm,0.025mm and 0.010mm.

In another embodiment, the fill factor of the light extraction features, light turning features, or low angle guiding features, defined as a percentage of the area comprising square centimeter features in the light emitting region, surface, or layer of the lightguide or film, is selected from one of the group of less than 80%, less than 70%, less than 60%, less than 50%, less than 40%, less than 30%, less than 20%, and less than 10%. The fill factor can be measured over the full light emitting square centimeter surface area or area of the light guide or film (the area bounded by the regions being the direction of all light emitted in the plane of the light guide) or can be the average of the light emitting area of the light guide. The fill factor can be measured when the light emitting device is in an on state or an off state (no light emission), where in the off state the light extraction features are defined as the visual discontinuities normally seen by a person with average visual acuity at a distance of less than 10 centimeters.

The light extraction region may include a volumetric scattering region with dispersed phase domains, voids, the absence of other materials or regions (gaps, voids), air gaps, boundaries between layers and regions, and other refractive index discontinuities within its volume other than coplanar layers with parallel interface surfaces. In one embodiment, the light extraction region includes angled or curved surfaces or volumes of light extraction features that redirect a first redirection percentage of light to within 5 degrees of a normal to a light emission surface of the light emitting device or within 80-90 degrees or 85-90 degrees of a direction perpendicular to the light emission surface of the light emitting device. In another embodiment, the first redirection percentage is greater than one selected from the group of 5, 10, 20, 30, 40, 50, 60, 70, 80, and 90. In one embodiment, the light extraction features are light redirecting features, light extraction regions or light out-coupling features.

In one embodiment, the lightguide or lightguide region includes light extraction features in multiple regions. In one embodiment, the light guide or light guide region comprises light extraction features on or in at least one selected from one of an outer surface, two outer surfaces, two outer opposing surfaces, two outer surfaces and at least one region disposed between the two outer surfaces, an outer surface within two different volumetric regions within a plurality of volumetric planes, two different volumetric regions substantially within two different volumetric planes parallel to the at least one outer surface or light emission surface or plane, within the plurality of volumetric surfaces. In another embodiment, a light emitting device includes a light emitting region on a lightguide region of a lightguide that includes more than one light extraction feature region. In another embodiment, one or more light extraction features are disposed on top of another light extraction feature. For example, the grooved light extraction features may include light scattering hollow microspheres that may increase the amount of light extracted from the lightguide or the light scattering hollow microspheres may further scatter or redirect the light extracted by the grooves. More than one type of light extraction feature may be used within the volume of the lightguide or lightguide region, on their surface, or a combination thereof.

In one embodiment, a first lightguide comprising a thin film layer includes light extraction features, a second lightguide is defined by a surface of a light redirecting optical element and a surface of the first lightguide, and the light redirecting optical element includes light redirecting or light turning features that are also light extraction functions of the second lightguide.

In another embodiment, the light extraction features are grooves, indentations, curved or angled features that redirect a portion of light incident in a first direction to a second direction within the same plane by total internal reflection. In another embodiment, the light extraction features redirect a first portion of light incident at a first angle to a second angle greater than the critical angle in a first output plane and increase the full width at half maximum intensity in a second output plane orthogonal to the first output plane. In another embodiment, the light extraction features are regions comprising grooves, indentations, curved or angled features, and further comprising substantially symmetric or isotropic light scattering regions of a material such as dispersed voids, beads, microspheres, substantially spherical regions, or a collection of randomly shaped regions in which the average scattering profile is substantially symmetric or isotropic. In another embodiment, the light extraction features are regions comprising grooves, indentations, curved or angled features, and further comprise substantially anisotropic or asymmetric light scattering regions of a material such as dispersed elongated voids, stretched beads, asymmetrically shaped elliptical particles, fibers, or a collection of shaped domains wherein the average scattering profile is substantially asymmetric or anisotropic. In one embodiment, the bi-directional scattering distribution function (BSDF) of the light extraction features is controlled to create a predetermined light output profile of the light emitting device or a light input profile to the light redirecting element.

In one embodiment, the at least one light extraction feature is an array, pattern or arrangement of wavelength converting materials selected from fluorophores, phosphors, fluorescent dyes, inorganic phosphors, photonic band gap materials, wavelength converting materials for quantum dots, fluorescent proteins, fusion proteins, fluorophores with specific functional groups attached to proteins, quantum dot fluorophores, small molecule fluorophores, aromatic fluorophores, conjugated fluorophores and fluorescent dye scintillators, phosphors (e.g., cadmium sulfide), doped rare earth phosphors and other known wavelength converting materials.

In one embodiment, the light extraction features are reflective materials that are specular, diffuse, or a combination thereof. For example, the light extraction features may be substantially specularly reflective ink (e.g., coated on a groove) disposed at an angle, or substantially diffusely reflective ink, such as an ink comprising titanium dioxide particles in a methacrylate-based binder (white paint). Alternatively, the light extraction features may be a partially diffusely reflective ink, such as an ink with small silver particles (micron or submicron, spherical or non-spherical, plate or non-plate or silver (or aluminum) coated onto the platelet) that also contains titanium dioxide particles. In another embodiment, the degree of diffuse reflection is controlled to optimize at least one of the angular output of the device, the degree of collimation of the light output, and the percentage of light extracted from the region.

The pattern or arrangement of light extraction features may vary in size, shape, pitch, position, height, width, depth, shape, orientation in the x, y or z direction. Patterns and formulas or equations that help determine the arrangement to achieve spatial luminance or color uniformity are known in the art of edge-lit backlights. In one embodiment, a light emitting device includes a thin film based lightguide including light extraction features disposed below micro-cylinders (lenses), wherein the light extraction features are disposed substantially in the form of dashed lines below the micro-cylinders such that light extracted from the line features has a lower angular FHWM intensity after being redirected from a cylindrical lens array light redirecting element and the length of the dashed lines can be varied to aid uniformity of light extraction. In another embodiment, the dashed pattern of light extraction features varies in the x and y directions (where the z direction is the optical axis of the light emitting device). Similarly, a two-dimensional microlens array film (either a close-packed or regular array) or arrangement of microlenses may be used as the light redirecting elements, and the light extraction features may include regular, irregular, or other arrangements of circles, ovals, or sizes, shapes, or positions in the x-direction, y-direction, or combinations thereof, possibly in other patterns or shapes that differ. In one embodiment, the pitch, a first dimension of a feature in a first direction perpendicular to a thickness direction of the film, a second dimension of a feature in a second direction perpendicular to the first direction and perpendicular to the thickness direction, a dimension of a feature in the thickness direction; at least one of the density of features in the first direction and/or the second direction varies in the first direction and/or the second direction. In one embodiment, the non-uniform spacing of the low angle guiding features in the first and/or second directions, the feature size or density being used to direct light to an angle less than the critical angle of one or more interfaces of the core region, has a spatially uniform luminous flux such that light coupled through a cladding layer or region of higher refractive index than cladding layers or regions on opposing surfaces of the core region of the light guide is incident on one or more light turning features that can direct light into a range of angles of thirty degrees from the thickness direction of the light guide in the light emitting region. In one embodiment, varying the pitch, feature size or density of the low-angle directing features in the first direction and/or the second direction enables spatial control of the light flux redirected towards the light-turning features, where the low-angle directing features do not moire interfere with an object illuminated by the light-emitting device (e.g., a reflective or transmissive liquid crystal display). Thus, in this example, the pitch of the light turning features can be selected to be a constant pitch at which moire interference does not occur, and uniformity of light reaching the illuminated object can be achieved by spatially varying the pitch, feature size, or density of the low angle directing features. In one embodiment, a method of providing uniform illumination for an object includes providing multiple types of light directing features (e.g., low angle directing features and light turning features), wherein uniformity is provided by varying a pitch, size, or density of a first type of features, and redirecting light away from the light guide to illuminate the object is achieved by a second type of features having a substantially constant pitch, size, and/or density such that a moire contrast between the light directing features and the illuminating object is less than one selected from the group of 50%,40%,30%,20%, and 10%. The low angle guide features may be formed on the surface or within the volume of the material, and the material may be a thermoplastic, thermoset or adhesive material. In one embodiment, the low angle guiding features are light extraction features. In another embodiment, the low angle guiding features are light extraction features for the first lightguide and the second lightguide. In another embodiment, the light emitting device includes low angle guiding features in two or more layers or regions in the light output direction of the light emitting device.

Width of light emitting region

In one embodiment, the total width of the array of coupling lightguides at which they meet the light mixing region, lightguide region or light emission region is less than the average width, maximum width or width of the light emission region or lightguide in a direction parallel to the array direction of the coupling lightguides (perpendicular to the direction of extension of the array of coupling lightguides). For example, in one embodiment, the total width of the array of coupling lightguides in the array direction is 15 millimeters, and the width of the light emitting area on the side of the light emitting area, which is 22 millimeters wide, is set to receive light from the light mixing area. In another example, the total width of the array of coupling light guides in the array direction where it meets the light mixing region is 15 mm, the width of the light guide region where it meets the light mixing region in the array direction is 15 mm, and the width of the light emitting region in the array direction extends in a direction perpendicular to the array direction such that the maximum width of the light emitting region in the array direction is 28 mm. The wider active area may be the result of, for example, the size and/or shape of the light redirecting or collimating optical element individually selecting the coupling light guide width and light guide (optionally with cladding layer) thickness to collect light from a particular light source emitting area size and/or to receive light from a light source. In one embodiment, the total width of the array of coupling lightguides (optionally including gaps therebetween) in the direction of the array where the coupling lightguides meet the light mixing region, lightguide region or light emitting region is less than one or more selected from the group: an average width of the light emitting region in a direction parallel to the array direction of the coupling lightguides, a width of a lateral side of the light emitting region positioned to receive light from the coupling lightguides and/or the light mixing region, and a maximum width of the light emitting region, a small value being selected from one of: at least 1 mm; at least 2 mm; greater than 4 mm; greater than 6 mm; greater than 10 mm; greater than 15 mm; greater than 20 mm; greater than 50% of the average width of the coupling lightguides; greater than 100% of the average width of the coupling lightguides; and greater than 1%,2%,5%, or 10% of the average width of the light emission area in the array direction of the coupling lightguides. In another embodiment, the average width of the light emission areas, the maximum width of the light emission areas, the width of the light emission areas along the side of the coupling lightguides closest to the light mixing area or the array direction, or the area of the lightguide comprising the light emission areas is at least 5%,10%,15%,20%,25%,30%, 35%,40%,50%,60%,70%,80%,90%,100%,125%,150%,200% larger than the total width (optionally including the gap) of the coupling lightguides in a direction parallel to the array direction of the coupling lightguides (perpendicular to the extension direction of the coupling lightguides) where the coupling lightguides intersect the light mixing area, the lightguide area, or the light emission areas.

Low angle guide feature

In one embodiment, at least one of the coupling light guide, the light mixing region or the light emitting region comprises two or more low angle guiding features. As used herein, a low angle guiding feature is a refractive, total internal reflection, diffractive or scattering surface, feature or interface that redirects light propagating within the total internal reflection light guide at a first angle into the thickness direction of the film in the core region; redirected to a second angle in the core region of the light guide, the second angle being smaller than the first angle, and having a total average deviation angle of less than 20 degrees. In another embodiment, the low angle directing feature redirects the incident light to a second angle having an average total divergence angle less than one selected from the group consisting of: from incident angles 18, 16, 14, 12, 10, 8, 6, 5, 4, 3, 2, and 1 degree. In one embodiment, the low angle guide features are defined by one or more reflective surfaces of a reflective spatial light modulator. For example, in one embodiment, the rear reflective surface of the reflective spatial light modulator includes low angle guiding features, and the reflective spatial light modulator is optically coupled to the light guide in the light emitting area. In another example, the reflective pixels of the reflective spatial light modulator are low angle guiding features and the reflective spatial light modulator is optically coupled to the light guide in the light emitting area.

In one embodiment, the pitch, a first dimension of a feature in a first direction perpendicular to a thickness direction of the film, a second dimension of a feature in a second direction perpendicular to the first direction and perpendicular to the thickness direction of the film; a dimension of the feature in a thickness direction; the density of features in the first direction and/or the second direction varies in the first direction and/or the second direction. In one embodiment, a non-uniform pitch, feature size or density is used to direct light at a spatially uniform luminous flux to an angle less than the critical angle of one or more interfaces of the core region of the light guide, such that light coupled through a cladding layer or region having a higher index of refraction than cladding layers or regions on opposing surfaces of the core region of the light guide is incident on one or more light turning features that direct the light to a range of angles within 30 degrees of the thickness direction of the light guide in the light emission region. In one embodiment, varying the pitch, feature size or density of the low-angle directing features in the first direction and/or the second direction enables spatial control of the light flux redirected towards the light turning features, where the low-angle directing features do not cause moire interference with an object illuminated by the light emitting device (e.g., a reflective or transmissive liquid crystal display). Thus, in this example, the pitch of the light turning features can be selected to be a constant pitch that does not produce moire interference, and achieving luminance uniformity of the light of the illuminated object is achieved by spatially varying the pitch, feature size, or density of the low angle directing features. In one embodiment, a method of providing uniform illumination for an object includes providing multiple types of light directing features (e.g., low angle light directing features and light turning features), wherein uniformity is provided by varying pitch, size or density of a first type of feature, and illuminating an object (e.g., a reflective or transmissive LCD) by redirecting light to an angle such that the light exits the light guide is achieved by providing a second type of feature having a substantially constant pitch, size and/or density such that a moire contrast between the light directing features and the illuminated object is less than one selected from the group of 50%,40%,30%,20% and 10%. The low angle guide features may be formed on the surface or within a volume of the material, and the material may be a thermoplastic, thermoset or adhesive material. In one embodiment, the low angle guiding features are light extraction features. In another embodiment, the light redirecting features are low angle redirecting features. In another embodiment, the low angle guiding features are light extraction features for the first lightguide and the second lightguide. In another embodiment, the light emitting device comprises low angle guiding features in two or more layers or regions in the light output direction of the light emitting device.

In one embodiment, the refractive index of the light redirecting element is less than or equal to the refractive index of the core layer of the film-based light guide. For example, in one embodiment, a reflective display includes a front light having light redirecting elements formed in a polycarbonate material having a refractive index of about 1.6 optically coupled to a polycarbonate light guide having a refractive index of about 1.6 using an adhesive having a refractive index of about 1.5 as a cladding layer, where the light guide contains low angle guiding features that are light extraction features of a thin film based light guide, and where the light guide is optically coupled to a reflective spatial light modulator on a side opposite the light redirecting optical elements using an adhesive having a refractive index of about 1.42 as a cladding layer.

In one embodiment, a light emitting device includes a film-based light guide comprising a core layer having a thickness between opposing surfaces of no greater than about 0.5 millimeters, wherein light propagates by total internal reflection between the opposing surfaces; a first cladding layer having a first side optically coupled to the core layer and an opposite second side; an array of coupling lightguides continuous with the lightguide region of the lightguide, each coupling lightguide of the array of coupling lightguides terminating at a boundary edge, and each coupling lightguide folded in a fold region such that the boundary edges of the array of coupling lightguides are stacked; a light-emitting region comprising a plurality of light extraction features arranged in a spatially varying pattern in the light-emitting region, the plurality of light extraction features frustrating total internal reflection light propagating within the core layer such that light exits from the core layer of the light-emitting region into the first cladding layer; a light source positioned to emit light toward the boundary edge of the stack, the light propagating within the array of coupling lightguides to the lightguide region, the light from each coupling lightguide merging and totally internally reflecting within the lightguide region; a light redirecting optical element optically coupled to the second side of the first cladding layer, the light redirecting optical element comprising light redirecting features that direct frustrated total internal reflection light from the light extraction features to the reflective spatial light modulator, the light redirecting features occupying less than 50% of a surface of the light redirecting optical element in a light emission region, and wherein the core layer has an average thickness in the light emission region, the light emission region has a maximum dimension in a plane of the light emission region perpendicular to a thickness direction of the core layer, the maximum dimension of the light emission region divided by the average thickness of the core layer in the light emission region is greater than 100, the light extraction features are low angle directing features, light exiting the light source has a full angular width at a first half maximum intensity in a plane perpendicular to the thickness direction of the film, light exiting the light emission device has a full angular width at a second half maximum intensity in a second plane parallel to the thickness direction, and light exiting the light source has a full angular width at a third half maximum intensity in a third plane parallel to the thickness direction of the film and perpendicular to the second plane. In one embodiment, the full angular width at the first half maximum intensity is less than one selected from the group consisting of: 1. 2, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45 and 50 degrees. In another embodiment, the full angular width at the second half maximum intensity is less than one selected from: 1. 2, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45 and 50 degrees. In another embodiment, the full angular width at the third half maximum intensity is less than one selected from the group consisting of: 1. 2, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45 and 50 degrees. In another embodiment, the first, second and third full angular widths are less than one selected from 1, 2, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45 and 50 degrees, respectively. In one embodiment, the light exiting the light source has a full angular width at half maximum intensity in a plane parallel to the thickness direction of the film that is greater than the first full angular width. For example, in one embodiment, in the light emission region, the light source is substantially collimated in a plane perpendicular to the thickness direction of the light guide, film or coupling light guide stack (or has an angular width at a first half maximum intensity of less than 10 degrees) and is not collimated at half maximum intensity or has a greater full angular width in a plane parallel to the thickness direction of the film or coupling light guide stack. In one embodiment, light from a light source passes through the coupling lightguide and into the lightguide region, it is redirected by the low angle directing component, passes through the first cladding layer, is redirected by the light redirecting optical element, and may have a small (e.g., less than 10 degrees) full angular width at the second half maximum intensity and a small (e.g., less than 10 degrees) full angular width at the third half maximum intensity due to collimation of the light source output (e.g., by the primary and/or secondary lenses or mirrors) due to collimation resulting from a combination of the low angle directing features, the refractive index difference between the two cladding layers, and the light redirecting features of the light redirecting optical element.

Reflective low angle guide feature

In one embodiment, a thin film-based light guide includes a light emitting region having low angle guiding features defined by an angled or curved interface between two materials having different refractive indices. In this embodiment, the difference in refractive indices may cause at least a portion of the incident light to be reflected at an average total deviation angle of less than 20 degrees below the incident angle. In one embodiment, light propagates within a core region of a light guide formed of a first core material having a first core refractive index, adjacent to the core region having a second refractive index less than the first refractive index, the light interacts with and is reflected by angled surface features embossed in the second and material such that at least a portion of the incident light is reflected with an average total deviation angle of less than 20 degrees from the incident angle. In one embodiment, the reflection at the angled or curved surface features is total internal reflection. For example, in one embodiment, a film-based light guide includes a light-emitting region having low-angle guiding features defined by an arrangement of linear surface features that make an average of 4 degrees with a direction parallel to the film surface (or core region layer interface) in the light-emitting region (making an average of 86 degrees with the surface normal of the film in the light-emitting region). In this example, a surface may be formed in the material of the core layer (e.g. by scribing or embossing) and a material with a lower refractive index may be placed near the surface such that a portion of the light incident on the surface is reflected at a total off-angle of 8 degrees (low angle guiding).

Refractive low angle guide feature

In another example, a film-based light guide includes a light-emitting region having low-angle guiding features defined by an arrangement of surfaces, wherein light passing through the surfaces is refracted (and optionally reflected) at least once to a new angle having an average total deviation angle of less than 20 degrees from the incident angle. In this example, a surface may be formed in the core material and have a material of lower refractive index adjacent to the surface, such that a portion of light incident on the surface is refracted at the interface (low angle guiding), reflected back through the lower refractive index material out of the second interface, back through the lower refractive index material, and through the light guide where it may exit the light guide at the opposite surface interface and then redirected by the light turning features.

Diffractive low angle steering features

In another example, a film-based light guide includes a light-emitting region having low-angle guiding features defined by an arrangement of diffractive features or surfaces, wherein light passing through the features or surfaces is at least diffracted (and optionally reflected) to a new angle, with an average total divergence angle from the incident angle of less than 20 degrees. For example, in one embodiment, one surface of the film-based light guide in the light emission area of the film includes a binary grating or blazed diffraction grating that redirects light incident at a first angle within a first angular bandwidth to a second angle different from the first angle, the second angle having an average total angular deviation from the incident angle of less than 20 degrees. In one embodiment, the pitch, size, length dimension, depth or angle of the one or more diffractive features or surfaces varies along a first direction from a first side of the light-emissive region to an opposite side in the direction of light propagation within the light-emissive region. For example, in one embodiment, the core region of the light guide in the light emission region includes a plurality of diffraction gratings having a repeating array of first, second, and third pitches, the plurality of diffraction gratings configured to diffract the average angle of incident light into an average total angular deviation of less than 20 degrees for blue, green, and red light, respectively.

Scattering low angle steering features

In another example, a film-based light guide includes a light emitting region having low angle guiding features defined by a layer or region with light scattering features, domains, or particles, wherein light passing through the light scattering layer or region is scattered at least once to a new angle having an average total divergence angle from the incident angle of less than 20, 15, 10, 8, 6, 4, 3, 2, or 1 degrees. In one embodiment, the light scattering layer or region may be formed adjacent to, above, below, or within a region of the core layer material. In this example, the light scattering layer or region may comprise or be defined by a light scattering interface having a regular or irregular surface structure on a first material having a first refractive index in contact with a second surface of a second material having a higher or lower refractive index than the first material, the second surface of the second material conforming to the first material surface such that a portion of light incident on the interface is scattered (forward and/or backward scattered) so as to leave the light guide at the surface interface and subsequently be redirected by the light turning features. In another embodiment, the film-based light guide includes low angle scattering features defined by a dispersed phase of a first material in a second matrix material (e.g., dispersed beads within a coating matrix). In this embodiment, incident light is scattered or refracted from one or more domain matrix interfaces such that the average total divergence and incidence angle of the incident light is less than 20 degrees. In one embodiment, the low angle guide features gradually redirect the light such that the light is deflected into an angle such that all or a portion of the light escapes the internal total internal reflection condition in the light guide.

Polarization dependent low angle steering features

In one embodiment, the low angle directing features redirect light having a first polarization more than light having a second polarization different from the first polarization. In another embodiment, the proportion of light having the first polarization that is redirected is greater than the proportion of light having the second polarization that is redirected, i.e. the polarization-guiding ratio, than one selected from the group consisting of: 1. 2, 3, 4, 5, 10, 15, 20, 30 and 50. For example, in one embodiment, the first polarization is s-polarized light and the second polarization is p-polarized light. In an embodiment, the low angle guiding feature or surface, or the material optically coupled to the low angle guiding feature or surface, comprises a substantially isotropic material, a birefringent material, or a tri-refractive material. In one embodiment, structured low angle directing features in the birefringent material are used to redirect light of the first polarization such that the average total divergence and incidence angles of the incident light are less than 20 degrees. For example, in one embodiment, light of a first polarization, e.g., s-polarized light, is directed at a low angle such that its angle is less than the critical angle of the side of the light guide optically coupled to a cladding layer having a higher index of refraction than the cladding layer on the opposite side. Thus, in this example, light of the desired polarization state, i.e., s-polarized light, is preferentially extracted by the low-angle directing features. In another embodiment, one or more layers or regions optically coupled to the light guide comprise a waveplate, birefringent material, tri-refractive material, or anisotropic material that converts light remaining in the light guide to a desired polarization state so that it can be redirected through the intersection of a second or subsequent polarization-dependent low-angle guiding feature.

Light turning feature

In one embodiment, the light emitting region of the light guide includes or is optically coupled to a layer or region having light turning features. As used herein, a light-turning feature is a refractive, total internal reflection, diffractive or scattering surface, feature or interface that redirects at least a portion of light incident within a first range of angles to a second range of angles different from the first range of angles, wherein the second range of angles is within 30 degrees of the thickness direction of the film in the light-emitting region. For example, in one embodiment, a polycarbonate film having grooves on a first outer surface is optically coupled to a film-based light guide using a pressure sensitive adhesive on a second surface of the polycarbonate film opposite the first outer surface. In this embodiment, light escaping to the light guide through the pressure sensitive adhesive (e.g., through the low angle guide features) is totally internally reflected at the groove-air interface in the polycarbonate film and is directed at an angle within 30 degrees of the thickness direction of the film in the light emission region, which further passes through the light guide to illuminate an object, such as a reflective LCD, and may optionally pass back through the light guide. In one embodiment, the light turning features receive light from the low angle directing features and redirect the light in the light emitting region at an angle of less than 30 degrees from the thickness direction. The light turning features may be formed on the surface or within a volume of the material, and the material may be a thermoplastic, thermoset or adhesive material. In one embodiment, the light turning features are embossed (UV cured or thermo-mechanically embossed) surface features in a light turning film that is optically coupled (e.g., by using a pressure sensitive adhesive) to a film-based light guide in the light emitting area. In one embodiment, a light turning film including light turning features on a first surface of the film is optically coupled to a light guide on a second surface opposite the first surface, the light turning features include recessed regions or grooves in the first surface, and the first surface is adhered to the second film in regions between the recessed regions or grooves using a pressure sensitive adhesive that leaves air gaps in the recessed regions or grooves. In this embodiment, the large refractive index difference between the polymeric light turning film and the air within the recessed regions or grooves increases the percentage of total internal reflected light at the interface compared to using an adhesive to effectively planarize the surface effectively with the tape by adhesive filling at the recesses or grooves. In another embodiment, the light turning film or region or layer including the light turning features extends to less than one of the group of 30%,20%,10%, and 5% of the light mixing area of the film-based light guide.

Size and shape of light turning features

In one embodiment, a light emitting device includes a film-based light guide that provides front illumination, such as front light for a reflective display, and the density of light turning features in the light emitting area of the film (or in the light emitting device or in a film optically coupled to the light emitting area) is less than about 50% to reduce unwanted second light aberrations (e.g., unwanted reflections) of light reflected from an illuminated object and back through the light guide and a layer or area containing the light turning features. In one embodiment, the areal density or density along the first direction of the light turning features in the light emitting region of the light guide is a first density selected from the group consisting of: less than 50%; less than 50%; less than 50%; less than 50%; less than 50%. Less than 40%; less than 30%; between 1% and 50%; between 1% and 40%; between 1% and 30%; between 5% and 30%; between 5% and 20%. In another embodiment, the density and/or size of the light turning features in the first direction and/or the second direction is less than the first density and the light turning features are not visible from a distance of 18 inches or more for a person with 1 arc of vision. In another embodiment, the angle subtended by the dimensions of the light turning features in the first direction and/or the second direction is less than 1 arc minute at a distance of 18 inches. In another embodiment, the area density in a plane including the first direction and the second direction of the light turning features is less than the first density, and the light turning features redirect less than one selected from the group consisting of: 50%,40%,30%,20% and 10% of the light reflected back to the illumination object from the illumination object (e.g., a reflective display). Thus, in this embodiment, the density and/or size of the light turning features may be configured to reduce light reflected back towards the subject, which may reduce the visible luminance contrast of the subject.

In another embodiment, the average depth of the light turning features in the thickness direction of the layer or region of the film comprising the light turning features is one or more selected from the group consisting of: between 1 and 500 microns, between 3 and 300 microns, between 5 and 200 microns, greater than 2 microns, less than 500 microns, less than 200 microns, less than 100 microns, less than 75 microns, less than 50 microns, and less than 10 microns.

In another embodiment, the average width of the light-turning features in the direction of propagation of light from the first input side of the light-emitting region of the light guide to the opposite side of the light-emitting region of the light guide is one or more of the group selected from: between 2 and 500 microns, between 5 and 300 microns, between 10 and 200 microns, greater than 5 microns, less than 500 microns, less than 200 microns, less than 100 microns, less than 75 microns, less than 50 microns, less than 25 microns, and less than 10 microns.

In one embodiment, the light turning features include one or more of: angled surface features, curved surface features, rough surface features, random surface features, asymmetric surface features, scored surface features, cut surface features, non-planar surface features, stamped surface features, molded surface features, compression molded surface features, thermoformed surface features, milled surface features, composite features of symmetrically or asymmetrically shaped materials, laser ablated surface features, embossed surface features, coated surface features, injection molded surface features, extruded surface features, and one of the foregoing features positioned in a light guide volume.

In one embodiment, a reflective display includes a light emitting device with a thin film based light guide and a reflective spatial light modulator. In this embodiment, the light emitting device includes a light redirecting optical element with light redirecting or turning features that have a dimension in a plane orthogonal to the thickness direction of the film-based light guide that is greater than the average dimension of the pixels of the reflective spatial light modulator, or greater than 2, 3, 4, 5, 7, 10, 20, 30, or 50 pixels of the average dimension.

In another embodiment, the ratio of the average pitch between the light redirecting or light turning features to the average size of the light redirecting or light turning features in a direction orthogonal to the thickness direction of the thin-film based light guide is greater than a selected one of 1, 1.5, 2, 3, 4, 5, 7, 10, 15, 20, 30, 40, 50, 70, and 100.

Pitch of light turning features

In one embodiment, the average pitch or spacing between the light redirecting or turning features is constant. In one embodiment, the average pitch of the light-turning features in the direction of light propagation from the first input side of the light-emitting region of the light guide to the opposite side of the light-emitting region of the light guide (e.g., the direction of the average propagation angle of the light guide within the light-emitting region) is one or more of the group of: between 5 and 500 microns, between 10 and 300 microns, between 20 and 200 microns, greater than 5 microns, less than 500 microns, less than 200 microns, less than 100 microns, less than 75 microns, and less than 50 microns. In an embodiment, the pitch of the light turning features is substantially constant. In one embodiment, the pitch of the light turning features or light redirecting features is set to reduce the moire contrast with regularly spaced elements of the illuminated object (e.g., reflective or transmissive LCDs).

In a light emitting device such as a display, visibility of a moire interference pattern may visually distract and luminance uniformity is reduced. The visibility or luminance contrast of the moire pattern is defined as LMmax-LMmin/(LMmax + LMmin), where LMmax and LMmin are the maximum and minimum luminance, respectively, along a cross section substantially perpendicular to the repeating moire pattern when the element is illuminated. In one embodiment, the light emitting device including the light turning features or the light redirecting features has a lower moire contrast such that the moire contrast is less than selected from 50%, 40%,30%,20% and 10%. Moire contrast can be reduced by switching the pitch of the light turning features or light redirecting features relative to the regular features of the illuminated object so that the moire contrast is small enough to be invisible to the naked eye or invisible without close scrutiny. Moir contrast may be reduced or eliminated altogether by one or more of the following methods: adjusting the pitch of the light turning features or light redirecting features, rotating the light turning features or light redirecting feature illumination relative to a regular array of features in the object, randomizing the pitch of the light turning features or light redirecting features, or increasing the spacing between the light turning features or light redirecting features and the illuminated object.

In another embodiment, the light redirecting or turning features are separated from the pixels of the spatial light modulator by a first distance, wherein the first distance is greater than one selected from the group consisting of: 0.05, 0.1, 0.2, 0.3,0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, and 2 millimeters. In another embodiment, a light emitting apparatus includes a lens positioned to receive light redirected by a light redirecting feature or a light turning feature reflected or transmitted through a spatial light modulator, wherein a modulation transfer function of the lens is less than 0.5 at a first distance or location of the light turning feature or the light redirecting feature and the modulation transfer function of the lens is greater than 0.7 on a plane containing pixels of the spatial light modulator. For example, in one embodiment, a head-mounted display includes a film-based light guide, a light redirecting element, a reflective spatial light modulator, and a lens (or combination of lenses) to magnify a pixel of the reflective spatial light modulator, wherein a light redirecting feature of the light redirecting element is a first distance from the pixel of the reflective spatial light modulator such that a modulation transfer function of the light redirecting feature is less than 0.5 and the light redirecting feature is unrecognizable or nearly unrecognizable to a person with an average vision of 1 arc minute. Similarly, in a projection system, the modulation transfer function of the lens for the location of the light turning feature or the light redirecting feature may be less than 0.5.

By adjusting the pitch of the light turning features, the moire contrast can be reduced when the light turning features are substantially parallel to the features in the illuminated object. In one embodiment, the ratio between the pitch between the array of light turning features and the pitch of conventional features in the illuminated object (e.g., pixels in a display) is equal to 1/(N + 0.5), where N is an integer, and moire contrast is reduced or eliminated. The pitch ratio from 0.9/(N + 0.5) to 1.1/(N + 0.5) has a lower moire visibility. In one embodiment, the pitch of the light turning features and the pitch of the regular array of elements on the illuminated object (the regular array of pixels in a reflective LCD) are according to the above equation and have an acceptable level of moire visibility. In one embodiment, a light emitting apparatus includes light turning features having a first pitch P1, the light turning features positioned to redirect light to an angle within 30 degrees from the thickness direction of the film toward an illuminated object, the illuminated object having a regular array of elements (e.g., pixels in a reflective LCD) having a second pitch P2, where 0.9/(N + 0.5) < P2/P1< 1.1/(N + 0.5), where N is an integer.

Polarization dependent light turning features

In one embodiment, the light turning features redirect light having a first polarization more than light having a second polarization different from the first polarization. In another embodiment, the proportion of light having the first polarization that is redirected is greater than the proportion of light having the second polarization that is redirected, i.e. the polarization-guiding ratio, than one selected from the group consisting of: 1. 2, 3, 4, 5, 10, 15, 20, 30 and 50. For example, in one embodiment, the first polarization is s-polarized light and the second polarization is p-polarized light. In an embodiment, the light turning features or surfaces, or the material optically coupled to the light turning features or surfaces, comprise a substantially isotropic material, a birefringent material, or a tri-refractive material. In one embodiment, structured light turning features in the birefringent material are used to redirect light of the first polarization such that the average total divergence and incidence angle of the incident light is less than 20 degrees. For example, in one embodiment, light from a low angle directing feature, e.g., s-polarized light, incident on a light turning feature of a first polarization is directed in the light emitting region at less than 30 degrees from the thickness direction of the film so that it can escape the film-based light guide in the light emitting region, e.g., to illuminate a reflective display, and can optionally return through the light guide. Light of the second polarization may pass through the light turning features and be totally internally reflected at interfaces further away from the core region of the light guide. In this example, light of the second polarization may be changed to the first polarization state and recycled within the light guide and optionally the layers optically coupled to the light guide. Thus, in this example, light of a desired polarization state, e.g., s-polarized light, is preferentially directed to an angle such that it can be transmitted out of the light guide and layers by the light-turning features. The light turning features may directly couple light out of the light guide without returning through the core region of the light guide, or the light turning features may direct light to an opposite side of the light guide, toward the subject for front illumination. In another embodiment, one or more layers or regions optically coupled to the light guide comprise a waveplate, birefringent material, tri-refractive material, or anisotropic material that converts light remaining in the light guide to a desired polarization state such that it can be redirected through the intersection of a second or subsequent polarization-dependent light-turning feature.

Multiple light guides

In one embodiment, a light emitting apparatus includes more than one light guide to provide one or more of: color sequential display, local dimming backlight, red, green and blue light guides, animation effects, multiple messages of different colors, NVIS and daylight mode backlights (e.g., one for NVIS and one for daylight), tiled light guides or backlights, and large area light emitting devices including smaller light emitting devices. In another embodiment, a light emitting device includes a plurality of light guides optically coupled to one another. In another embodiment, at least one of the light guides or parts thereof comprises an area with anti-blocking features, so that the light guides do not directly couple light into each other due to contact.

Multiple light guides providing pixelated colors

In one embodiment, a light emitting device includes a first light guide and a second light guide arranged to receive light from a first light source and a second light source, respectively, through two different optical paths, wherein the first light source and the second light source emit light of different colors, and light emitting areas of the first and second light guides include pixelated areas that include a spatial separation in a plane of a light output plane of the light emitting device at the pixelated areas (e.g., a separation in a thickness direction of the thin film based light guide). In one embodiment, the colors of the first and second pixelated light-emissive regions are perceived without magnification by an observer with a visual sensitivity of 1 arc minute at a distance of twice the diagonal (or diameter) of the light-emissive region as an additive color to be combined as a sub-pixel. For example, in one embodiment, the colors in different spatial regions of the display are spatially controlled to achieve different colors in different regions, similar to liquid crystal displays using red, green, and blue pixels and LED signage using a combination of red, green, and blue LEDs. For example, in one embodiment, a light emitting device includes a red light emitting light guide optically coupled to a green light emitting light guide coupled to a blue light guide. The respective regions and light output of the light guide of the present embodiment are explained below. In a first light emission region of the light emitting device, the blue and green light guides do not have light extraction features, while the red light guide has light extraction features such that the first light emission region emits red in one or more directions (e.g., towards or from a spatial light modulator of the light emitting device). In a second light emitting region of the light emitting device, the red and green light guides do not have light extraction features, while the blue light guide has light extraction features such that the second light emitting region emits blue light in one or more directions. In a third light emitting area of the light emitting device, the blue and red light guides have light extraction features, while the green light guide does not have any light extraction features, such that the third light emitting area emits violet light in one or more directions. In a fourth light emitting region of the light emitting device, the blue, green and red light guides have light extraction features such that the fourth light emitting region emits white light in one or more directions. Thus, by using a plurality of light guides to create light emitting areas emitting light of different colors, for example, the light emitting device, display or sign may be multi-colored, while the different areas emit different colors simultaneously or sequentially. In another embodiment, the light-emitting region includes light extraction features of appropriate size and density on the plurality of lightguides to reproduce, for example, full color graphics, images, indicia, logos, or photographs.

Stacked light guide

In one embodiment, a light emitting apparatus includes at least one thin film light guide or light guide region for receiving and transmitting light transmitted from a second thin film light guide or light guide region such that light from the second light guide improves luminance uniformity, increases illumination uniformity, improves color uniformity, increases illumination of the light emitting region or provides a spare light emitting region when a component failure causes light from the first light guide to fall short of an indicator (e.g., color uniformity, luminance uniformity or luminance) in an overlap region.

Light guide folded around a component

In one embodiment, at least one is selected from the group consisting of: the light guide, the light guide regions, the light mixing region, the plurality of light guides, the coupling light guide and the light input coupler are bent or folded such that a part of the light emitting device is hidden from view, is located behind another part or the light emitting region, is partially or completely closed. Such components around which they may be bent or folded include components of the light emitting device such as light sources, electronics, drivers, circuit boards, heat transfer elements, spatial light modulators, displays, housings, holders or other components such that these components are disposed behind a folded or bent light guide or other area or component. In one embodiment, a front light for a reflective display includes a light guide, a coupling light guide, and a light source, where one or more regions of the light guide are folded and the light source is disposed substantially behind the display. In one embodiment, the light mixing region comprises a fold, and the light source and/or the coupling lightguide are disposed substantially on a side of the film-based lightguide opposite a light emitting region of the device or the reflective display. In one embodiment, a reflective display includes a lightguide folded such that an area of the lightguide is disposed behind a reflective spatial light modulator of the reflective display. In an embodiment, the fold angle in one plane is between 150 and 210 degrees. In another embodiment, the fold angle is substantially 180 degrees in one plane. In one embodiment, the fold angles are substantially 150 degrees and 210 degrees in a plane parallel to an optical axis of light propagating in the film-based light guide. In one embodiment, more than one input coupler or component is folded behind or around the light guide, light mixing region or light emitting region. In this embodiment, for example, two light input couplers from opposite sides of the light emitting area of the same film may be arranged adjacent to each other or utilize a common light source and folded behind the spatial light modulator of the display. In another embodiment, tiled light emitting devices include light input couplers folded behind each other and adjacent to or physically coupled to each other, using the same or different light sources. In one embodiment, the light source or the light emitting area of the light source is arranged in a volume bounded by an edge of the light emitting area and a normal to the light emitting area, the light emitting area being located on a side of the light guide opposite to the viewing side. In another embodiment at least one of the light source, the light input coupler, the coupling light guide or the region of the light mixing region is arranged behind the light emission region (on the side of the light guide opposite the viewing side) or within a volume bounded by an edge of the light emission region and a normal to the light emission region of the side of the light guide opposite the viewing side.

In another embodiment, the light guide region, light mixing region or light guide body extends across at least a portion of the array of coupling light guides or light emitting device components. In another embodiment, the light guide region, light mixing region or light guide body extends on a first side of the array of coupling light guides or a first side of the light emitting device component. In another embodiment, the light guide region, light mixing region, or light guide body extends over the first and second sides of the array of coupling light guides. For example, in one embodiment, the body of the film-based light guide extends through both sides of a stack of coupling-in light guides having a substantially rectangular cross-section. In one embodiment, the array stack of coupling lightguides is oriented in a first orientation direction substantially parallel to its stack surface and towards a light propagation direction within the coupling lightguides, and the light emission area is oriented in a second orientation parallel to an optical axis of light propagating within the light emission area, wherein the orientation difference angle is an angular difference between the first direction and the second direction. In one embodiment, the orientation difference angle is selected from the group consisting of: 0 degrees, greater than 0 degrees and less than 90 degrees, between 70 degrees and 110 degrees, between 80 degrees and 100 degrees, greater than 0 degrees. Less than 180 degrees, between 160 and 200 degrees, between 170 and 190 degrees, and greater than 0 and less than 360 degrees.

In one embodiment, at least one selected from the group of: the light guide, the light guide region, the light mixing region, the plurality of light guides, the coupling light guide and the light input coupler are bent or folded such that they wrap more than once around the components of the light emitting device. For example, in one embodiment, the light guide is wrapped around the coupling light guide two, three, four, five, or more times. In another embodiment, the light guide, light guide region, light mixing region, plurality of light guides, coupling light guide or light input coupler may be bent or folded such that it wraps completely around the components of the light emitting device and partially wraps around it again. For example, the light guide may be wrapped 1.5 times (once around, half around) around the relative position holding element. In another embodiment, the light guide region, light mixing region or light guide body further extends across a third, fourth, fifth or sixth side of the array of coupling light guides or light emitting device components. For example, in one embodiment, the light-mixing region of the film-based light guide extends completely around four sides of the relative position-holding element, and again across the side (fifth side). In another example, the light-mixing region is wrapped more than three times around the coupling light guide stack and the relative position maintaining element.

In one embodiment, wrapping a lightguide, lightguide region, light mixing region, plurality of lightguides, coupling lightguides, or light input couplers around a component provides a compact method for extending the length of a region of a lightguide. For example, in one embodiment, the light mixing region is wrapped around the stack of coupling lightguides to increase the light mixing distance within the light mixing region such that the spatial color uniformity or luminous flux uniformity of the light entering the light emission region is improved.

In one embodiment, the wrapped or extended region of the light guide is operably coupled to a stack of coupled light guides or a component of a light emitting device. In one embodiment, the wrapped or extended region of the light guide is held by an adhesive to a stack of coupled light guides or a component of the light emitting device. For example, in one embodiment, the light-mixing region includes a layer of pressure sensitive adhesive cladding that extends or wraps around and adheres to one or more surfaces of one or more coupling lightguides or components of a light-emitting device. In another embodiment, the light-mixing zone comprises a layer of pressure sensitive adhesive adhered to at least one surface of the relative position-retaining element. In another embodiment, a portion of the film-based light guide includes a layer that extends or wraps to one or more surfaces of one or more coupling light guides or components of the light emitting device. In another embodiment, the wrapped or extended region of the light guide extends across one or more surfaces or sides, or is wrapped around one or more light sources. The wrapping or extension of the light guide or light guide region across one or more sides or surfaces of the stack of coupling light guides or a component of the light emitting device may occur by physically translating or rotating the light guide or light guide region, or may be accomplished by rotating the stack of coupling light guides or the component. Thus, the physical construction does not require a particular method to accomplish the wrapping or extending.

Light absorbing regions or layers

In one embodiment, the one or more cladding layers, the adhesive, the layers disposed between the light guide and the light guide region and the outer light emitting surface of the light emitting device, the patterned region on one or more surfaces of the film or within a volume of the film, the printed region, and the extruded region comprise a light absorbing material that absorbs a first portion of light in a first predetermined wavelength range.

Adhesive properties of light guides, films, cladding layers, or other layers

In one embodiment, one or more of the light guide, core, light transmissive film, cladding material and layers disposed in contact with the film layer have one or more of the following adhesive properties or comprise a material having one or more of the following: chemical bonding, dispersion bonding, electrostatic bonding, diffusion bonding and mechanical bonding of at least one component of the light-emitting device (for example a coated carrier film, an optical film, a rear polarizer in an LCD, a brightness enhancement film, another area of the light guide, a coupling light guide, a heat transfer component such as a foil comprising aluminum, or a white reflective film) or a component external to the light-emitting device, for example a window, a wall or a ceiling.

Light redirecting elements for redirecting light from a light guide

In one embodiment, a light emitting device includes a light guide having light redirecting elements disposed on or within the light guide and light extraction features disposed in a predetermined relationship relative to one or more of the light redirecting elements. In another embodiment, the first portion of the light redirecting element is disposed over the light extraction features in a direction substantially perpendicular to the light emission surface, the lightguide, or the lightguide region.

In another embodiment, the light redirecting element is arranged to redirect light redirected from the light extraction feature such that light exiting the light redirecting element is selected from a group that is more collimated than a similar light guide having a substantially planar surface; a full angular width at half maximum intensity in the first light output plane of less than 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees, or 5 degrees; in a first light output plane and a second light output plane orthogonal to the first light output plane, the half maximum intensity has a full angular width of less than 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees, or 5 degrees; and has a full angular width of less than 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees or 5 degrees at half maximum intensity in all planes parallel to the optical axis of the light emitting device.

In one embodiment, the lightguide includes a substantially linear array of micro-cylindrical mirrors disposed on at least one surface opposite the substantially linear array of light extraction features, wherein the light redirecting element collimates a first portion of the light extracted from the lightguide through the extraction features. In another embodiment, a light emitting device includes a cylindrical lens film light guide further including a coupling light guide, wherein the coupling light guide is disposed substantially parallel to the micro-cylindrical mirrors at the light guide region or the light mixing region, and the cylindrical lens film further includes linear regions of reflective ink light extraction features disposed substantially opposite the micro-cylindrical mirrors on opposite surfaces of the cylindrical lens film light guide and collimating light exiting the light emitting device. In another embodiment, the light extraction features are light redirecting features (e.g., TIR grooves or linear diffraction gratings) that redirect light incident in one plane much more than light incident from a plane orthogonal to the first plane. In one embodiment, the cylindrical lens film includes grooves on opposing surfaces of the micro-cylinder that are oriented at a first angle greater than 0 degrees relative to the micro-cylinder.

In another embodiment, a light emitting device includes a microlens array thin film light guide having a microlens array on one surface, and the film further includes regions that reflect ink light extraction features disposed substantially opposite the microlenses on the opposite surface of the cylindrical lenses, the thin film light guide and light emitted from the light emitting device being substantially collimated or having an angular FWHM luminous intensity less than 60 degrees. For example, the microlens array film can collimate light from the light extraction features in a radially symmetric direction. In one embodiment, the microlens array film is separated from the light guide by an air gap.

The width of the light extraction features (the reflected lines of ink in the cylindrical lens light directing film embodiment described above) will contribute to the degree of collimation of the light exiting the light emitting device. In one embodiment, the light redirecting element is disposed substantially opposite the light extraction features, and an average width of the light extraction features in the first direction divided by an average width of the light redirecting element in the first direction is less than one selected from the group consisting of: 1. 0.9, 0.7, 0.5, 0.4, 0.3, 0.2 and 0.1. In another embodiment, a focal point of collimated visible light incident on the light redirecting element in a direction opposite the surface including the light extraction features is within one selected from the group consisting of no more than 5%,10%, 20%,30%,40%,50% and 60% of a width of the light redirecting element from the light extraction features. In another embodiment, the focal length of the at least one light redirecting element or the average focal length of the light redirecting elements is less than one selected from the group of 1 millimeter, 500 microns, 300 microns, 200 microns, 100 microns, 75 microns, 50 microns, and 25 microns when illuminated with collimated light from a direction opposite the light guide.

In one embodiment, the focal length of the light redirecting element divided by the width of the light redirecting element is less than one selected from the group of 3, 2, 1.5, 1, 0.8 and 0.6. In another embodiment, the optical f-number of the light redirecting element is less than one selected from the group consisting of 3, 2, 1.5, 1, 0.8, and 0.6. In another embodiment, the light redirecting element is a linear Fresnel lens array having a refractive Fresnel structure in cross-section. In another embodiment, the light redirecting element is a linear Fresnel-TIR hybrid lens array having a cross-section of refractive Fresnel structures and total internal reflection structures.

In another embodiment, the light redirecting element is arranged to redirect light redirected from the light extraction feature such that a portion of the light exiting the light redirecting element is redirected with an optical axis at an angle greater than 0 degrees from a direction perpendicular to the light emission area, the light guide or the light emission surface. In another embodiment, the light redirecting element is arranged to redirect light redirected from the light extraction features such that light exiting the light redirecting element is redirected to an optical axis substantially parallel to a direction perpendicular to the light emission area, the light guiding area, the light guide or the light emission surface. In another embodiment, the light redirecting element reduces the full angular width at half maximum intensity of light incident on the area of the light redirecting element and redirects the optical axis of light incident on the area of the redirecting element at a first angle to a second angle different from the first angle.

In another embodiment, the angular spread of light redirected by the light extraction features is controlled to optimize the light control factor. One light control factor is the percentage of light that reaches adjacent light redirecting elements that will redirect the light to an undesirable angle. This may cause side lobes or cause light to be output to an undesired area. For example, a strong diffusely reflected scattered light extraction feature located directly under a micro-cylinder in a cylindrical lens array may scatter light into an adjacent micro-cylinder, such that there is one side lobe at a higher angular intensity, which is undesirable in applications where a collimated light output is required. Similarly, light extraction features that redirect light over a large angular range, such as hemispherical domes with relatively small radii of curvature, can also redirect light into adjacent micro-lenticules and create side lobes. In one embodiment, a bi-directional scattering distribution function (BSDF) of the light extraction features is controlled to direct a first portion of incident light in a first angular range into the light redirecting element in a second angular range to produce a predetermined third angular range of light exiting the light emitting device.

Light redirecting element

As used herein, a light redirecting element is an optical element that redirects a portion of light of a first wavelength range that is incident within a first angular range into a second angular range that is different from the first angular range. In one embodiment, the light redirecting element comprises at least one element selected from the group consisting of: refractive features, total internal reflection features, reflective surfaces, prism surfaces, microlens surfaces, diffractive features, holographic features, diffraction gratings, surface features, volume features, and lenses. In another embodiment, the light redirecting element comprises a plurality of the foregoing elements. The plurality of elements may be a 2-D array (e.g., a grid of microlenses or a close-packed array of microlenses), a one-dimensional array (e.g., an array of cylindrical lenses), a random arrangement, a predetermined irregular spacing, a semi-random arrangement, or other predetermined arrangement. The elements may include different features, have different surface or volume features or interfaces, and may be disposed at different thicknesses within the volume of the light redirecting element, light guide or light guide region. The individual elements may vary in the x, y or z direction by at least one selected from the group consisting of: height, width, thickness, position, angle, radius of curvature, spacing, direction, pitch, cross-sectional profile and position in the x, y or z axis. In an embodiment, the light redirecting element includes a light turning feature.

In one embodiment, the light redirecting element is optically coupled to the light guide in at least one region. In another embodiment, the light redirecting elements, films or layers comprising the light redirecting elements are separated by air gaps in a direction perpendicular to the light guide, the light guide region or the light emission surface of the light guide. In another embodiment, the light guide region or the light emission surface of the light guide is disposed substantially between two or more light redirecting elements. In another embodiment, a cladding layer or cladding region is disposed between the light guide or light guide region and the light redirecting element. In another embodiment, the light guide or light guide region is arranged between two light redirecting elements, wherein light is extracted from the light guide or light guide region from both sides and redirected by the light redirecting elements. In this embodiment, the backlight may be designed to emit light in opposite directions to illuminate both displays, or the light emitting device may be designed to eject light emitted from the light guide in opposite directions back through the light guide from the other side, by adding reflective elements.

In another embodiment, the average or maximum dimension of the light redirecting elements in at least one output plane of the light redirecting elements is equal to or less than one selected from the group of 100%,90%,80%,70%,60%,50%,40%,30%,20% and 10% of the average or maximum dimension of a pixel or sub-pixel of the spatial light modulator or display. In another embodiment, the backlight includes a light redirecting element that redirects light toward within 30 degrees FWHM of the display, where each pixel or sub-pixel of the display receives light from two or more light redirecting elements.

In another embodiment, the light redirecting element is a collection of prisms arranged to refract and totally internally reflect light towards the spatial light modulator. In one embodiment, the set of prisms is a linear array of prisms having apex angles between 50 and 70 degrees. In another embodiment, the set of prisms is a linear array of prisms having apex angles between 50 and 70 degrees, a light transmissive material has been applied or disposed in regions between the prisms and the light guide or regions of the light guide such that the film effectively planarizes the prisms in these regions, and the set of prisms is now a two-dimensionally varying arrangement of prisms (and thus no longer appears as a linear array on the surface). In one embodiment, other forms of light redirecting elements, inverse prisms, mixing elements or combinations thereof having refractive or total internal reflection characteristics may be used. Modifications of elements such as "wavy" variations, variations in size, dimensions, shape, spacing, pitch, curvature, direction and structure in the x, y or z direction, combinations of curved and straight portions, and the like are known in the art. Such elements are known in the art of backlights and Optical films for displays and are included in the "Optical film to Optical cosmetic applications and brightness in liquid crystal displays" published by Lee et al in OPTICS EXPRESS,2007, 7/9, vol.15, no. 14, pages 8609-8618; aoyama et al, in "Hybrid normal-reverse prism coupler for light-emitting diode backlight systems" published "in" applied optics ", no. 10/1 2006, vol.45, no. 28, pp.7273-7278; japanese patent application No.2001190876, entitled "optical sheet", filed by Kamikita Masakazu; U.S. patent application Ser. No. 11/743,159; U.S. Pat. Nos. 7,085,060, 6,545,827, 5,594,830, 6,151,169, 6,746,130, and 5,126,882. In another embodiment, the at least one light extraction feature is centered on a first plane offset from the axis of the light redirecting element. In this embodiment, a portion of the light extraction features may intersect the optical axis of the light extraction features, or may be disposed sufficiently far from the optical axis such that it does not intersect the optical axis of the light extraction features. In another embodiment, the distance between the centers of the light extraction features and the respective light redirecting elements in the first plane varies across the array or arrangement of light redirecting elements.

In one embodiment, the positions of the light extraction features vary in at least a first plane relative to the positions of the respective light redirecting elements, and the optical axes of light emitted from different regions of the light emission surface vary relative to the direction of the light redirecting elements. In this embodiment, for example, light from two different areas of the planar light emitting surface may be directed in two different directions. In another example of this embodiment, light from two different regions (e.g. a bottom region and a side region) of a luminaire having a convex curved light emitting surface that is curved downwards is directed in the same direction (the optical axis of each region is directed downwards towards the nadir, wherein the optical axis of the light redirecting elements in the bottom region is substantially parallel to the nadir and the optical axis of the light redirecting elements in the side region is at an angle, e.g. 45 degrees, to the nadir). In another embodiment, the position of the light extraction features is further from the optical axis of the respective light redirecting element in an outer region of the light emission surface in a direction perpendicular to the micro-cylinder than in a central region of the light extraction area substantially on the axis, and the axis and the light emitted from the light emitting device are more collimated. Similarly, if the light extraction features are located farther from the optical axis of the light redirecting element than in a direction orthogonal to the micro-cylinder from the first edge of the light emission surface, the light emitted from the light emission surface may be directed substantially off-axis. Other combinations of the position of the light extraction features relative to the light redirecting element can be readily envisaged including varying the distance of the light extraction features from the optical axis of the light redirecting element in a non-linear manner, moving closer to the axis then away from the axis then closer to the axis in a first direction, moving away from the axis then closer to the axis then further in a first direction, the upper and lower apexes of the curved region of the light emitting surface having a sinusoidal cross-section having a (wavy) profile of the light extraction features substantially on the axis and the walls of the profile having light extraction features remote from the optical axis of the light redirecting element, regular or irregular variations in the separation distance of the light extraction features from the optical axis of the light redirecting element, etc.

Angular width control

In one embodiment, the widths of the light extraction features vary in at least a first plane relative to the respective widths of the light redirecting elements, and the full angular width at half maximum intensity of light emitted from the light redirecting elements varies across at least the first plane. For example, in one embodiment, a light emitting device includes a cylindrical lens array light directing film in which a central region of a light emitting surface in a direction perpendicular to micro-cylindrical mirrors includes light extraction features having an average width that is about 20% of the average width of the micro-cylindrical mirrors. An outer region of the light emission surface in a direction perpendicular to the micro-cylinder includes light extraction features having an average width of about 5% of the average width of the micro-cylinder, and a full width at half maximum intensity of light emitted from the central region is greater than a full width at half maximum intensity of light emitted from the outer region.

Off-axis light redirection

In another embodiment, the light redirecting element is arranged to receive light from the electro-optical element, wherein the optical properties in one or more regions can be selectively or globally changed by applying a voltage or current to the device. In one embodiment, the light extraction features are regions of polymer dispersed liquid crystal material in which light scattered from the light guide in a diffuse state is redirected by the light redirecting element. In another embodiment, the light extraction features have small inactive areas and larger active areas that are configured to change from substantially transparent to substantially transmissive diffusion (forward scattering) such that when used in conjunction with the light redirecting element, the display can be changed from a narrow display angle to a larger display angle by applying or removing a voltage or current to or from the electro-optic area or material. For example, lines of grooved light extraction features are disposed adjacent (x, y or z direction) a film comprising a wider line Polymer Dispersed Liquid Crystal (PDLC) material that is configured to change from substantially transparent to substantially diffuse upon application of a voltage between the electrodes. Other electro-optic materials may also be used, such as electrophoresis, electrowetting, electrochromic, liquid crystal electro-active, MEMS devices, smart materials and other materials whose optical properties can be altered by the application of a voltage, current or electromagnetic field.

Angular shadow visibility reduction

In some embodiments, the total width of the array of coupling lightguides where they meet the light mixing region, lightguide region or light emission region is less than the average width, maximum width or width of the light emission region or lightguide region in the direction of the array of coupling lightguides (perpendicular to the direction of extension of the array of coupling lightguides). In these embodiments with a larger light mixing area, light emission area or light guide area, the spatial and angular flux distribution of the light may create visible shadows, darker bands or darker angular bands due to the lower luminous flux incident on a particular area from a particular angular range. Thus, enlargement of the light mixing region, light guide region, and/or light emission region relative to the input region (the overall width of the coupling light guide inputting light into the light mixing region, light guide region, or light emission region along the array direction of the coupling light guide) may create a visible shadow region (e.g., a band of reduced luminance) on a display incorporating a front or backlight of a film-based light guide. The visible band is caused by the smaller luminous flux with a certain angular range originating from or appearing to originate (e.g. reflect) from an extra-wide area in the array direction of the array of coupling light guides of the light mixing area, the light guide area or the light emission area. This is particularly evident when the light extraction features or light redirecting features are sensitive to the angle of incidence, for example when the linear array of grooves is oriented such that the angle in the array direction of the linear array of grooves is greater than 0 degrees from the array direction of the array of coupling lightguides. In one embodiment, the angular shadow reduction method directs a first portion of incident light to a location within the light mixing region, light guide region, or light emission region that will receive less than 80%,70%,60%,50%,40%,30%,20%, and 10% of the total luminous flux exiting the array of coupling light guides without angular shadow reduction. In one embodiment, the width of the array of coupling lightguides in the array direction where the coupling lightguides meet the light mixing regions, the lightguide regions or the light emitting regions, respectively, is smaller than the mixing regions, the width of the array of coupling lightguides of the lightguide regions or the light emitting regions where the coupling lightguides meet the respective regions in the array direction, and the angular shadowing is reduced by an angular shadowing reduction method. The reduction in angular shading can be measured using a measure of spatial luminance uniformity. Angular shading is measured using a spatial luminance uniformity measurement across the light emitting area and is represented by dark (relatively low luminance) bands or dark stripes. In one embodiment, the luminance uniformity of light emitted from the light guide in the light-emitting area (or from a display that reflects light from the light-emitting area) along the length or width of the light-emitting area (or display) is greater than one selected from the group consisting of 60%,65%,70%,75%,80%, and 85%. Where the measurement includes light leaving the light emitting area (or display) corresponding to light that appears to come from an area of unwanted width, either directly or indirectly (actually occurring through reflection or scattering). The excess width region is a region of the light mixing region, the light guide region and/or the light emission region that extends beyond the total width of the array of coupling lightguides (or the total width of the light mixing region, wherein the total width of the light mixing region at the light emission region is the total width of the array of coupling lightguides) in the array direction of the array of coupling lightguides where the array of coupling lightguides meets the light mixing region, the light guide region or the light emission region, respectively. In this embodiment, light that directly appears to come from the extra-width region includes light that passes through or reflects from the element or feature (e.g., a light-mixing region of the film, a lateral edge of a light-guiding region or light-emitting region, or an internal light-guiding edge from the extra-width region, a light-scattering material or a light-reflecting or scattering surface). In another embodiment, it indirectly appears that the light emitted from the extra-width region comprises light reflected from elements or features of the light-emitting region other than the light-mixing region, the light-guiding region or the extra-width region (e.g. internal light-guiding edges, light-scattering material or light-reflecting or scattering surfaces) that correspond to the position and direction of the light that would be the same if the light were emitted from the extra-width region and propagated towards the light-emitting region.

The method of reducing the occurrence of angular shadowing, banding or banding may comprise one or more selected from the group consisting of: reducing the width of the excess width region; adding a wide-angle reflection or wide-angle light scattering feature on the light turning feature element; adding a wide-angle reflection or wide-angle light scattering feature to the light turning feature; increasing/increasing the amount of scattering in the light turning feature region; redirecting light in the light mixing region; adding a separate diffusing layer or material; adding additional turning features in the light emitting region that have a different refractive index than adjacent regions; using an internal light guiding edge or guide to direct light into a particular spatial location having a particular angular profile; and increasing the spacing or gap between the coupling lightguides.

Reducing the region of excess width

In one embodiment, the width of the light-mixing and/or light-guiding regions where the array of coupling lightguides meets the light-mixing and/or light-guiding region, respectively, is reduced or tapered to meet the overall width of the array of coupling lightguides in the array direction. This reduction in the width of the extra-width region increases the reflection of the lateral edge of the film in the region of the lightguide or light mixing region in the region near the array of coupling lightguides. In one embodiment, the width of the light guide region and/or the light mixing region (in a direction parallel to the array direction of the coupling light guides of the light guide region and/or the light mixing region) transitions in angular, curvilinear or stepwise increments from where the coupling light guides meet the light guide region and/or the light mixing region and the light emission region.

Adding wide-angle reflection or wide-angle scattering to light-turning features

In one embodiment, wide-angle reflective or wide-angle light-turning features are added to the light-turning feature elements (elements that include light-turning features), such as films with parallel grooves (light-turning films). In order to diffuse the incident light significantly in the lateral direction of the light guide (lateral direction in a plane perpendicular to the light emission surface of the light guide or the normal of the light emission surface), or specifically in the array direction of the array of coupling light guides, to reduce angular shadowing. In one embodiment, a light scattering material is printed or added to the light turning film that scatters incident light in a lateral direction. For example, in one embodiment, a disperse phase having a different index of refraction than the material of the substrate or surface is added to the volume of the light turning film (in the feature or substrate) to increase scattering. Similarly, a dispersed phase (e.g., a second polymeric material blended in an adhesive matrix material) can be added to the adhesive between the light guide and the light turning film. In another embodiment, printed patterns are added to one or more surfaces of the light turning film to increase the spread or reflected light of the light in the lateral direction toward the extra-width region to create a new virtual origin and direction of light reflection from the reflection of the scattered patterns to redirect the light so that it appears indirectly therebetween as if it came from the extra-width region and reduces the visibility of the angular shadow (increasing the relative luminance in the shadow region). The size and location of these printed areas may vary depending on the location and angular profile of the light in the light guide area, the light mixing area and/or the light emitting area. Other methods, materials, shapes, structures, and characteristics of printed scattering elements or volumetric or surface scattering elements for light turning elements to reduce angular shadowing can be the same as those of the light extraction features disclosed herein.

In one embodiment, the wide angle reflective or wide angle light turning features are masked by a light absorbing material on the viewer side. For example, in one embodiment, a white reflective ink is printed on the upper surface of the light turning film in a pattern of dots or other pattern or area, wherein the printed white dots have an average largest dimension in the plane of the film that is less than one or more selected from the group of 200 microns, 100 microns, 75 microns, 50 microns, 40 microns, 30 microns, 20 microns, 15 microns, 10 microns, and 8 microns. In another embodiment, a black light absorbing ink of substantially the same size (or larger) as the white dots or areas is printed over the white dots or areas (on the viewing side). In this embodiment, the black overprinting prevents reflective scattering of ambient light from the black printed dots, which can reduce the contrast of the display. Also, in another embodiment, the bottom surface (display side) of the light turning film may be printed with a pattern of black dots or areas, with a pattern of white dots (which may be smaller than the pattern of black dots or areas) being overprinted, so that, as shown in the previous example, the black dots or areas are on the viewing side, and therefore most, if not all, of the ambient light is absorbed before reaching the white dot pattern (or absorbed after passing through the light absorbing areas, reflected from the white dots or patterns, and after passing back through the light absorbing areas). Similar to white ink light scattering material in white dots or areas, a combination of black over silver (specular reflection) or black over light gray (partially specular reflection, partially diffuse reflection) (or silver over black, or light gray over black) may be used to achieve certain angular characteristics of reflectively scattered light, such as reduced visibility of angular shadows.

In another embodiment, silver printed dots or areas are printed between the printed white scattering dots or areas and the black dots or areas. In this configuration, the silver printed areas or dots reflect light scattered forward from the white printed dots or areas so that it does not pass through the black dots or areas but is absorbed. In this embodiment, less light is absorbed and less light is wasted than if black printed dots or areas were provided over white printed dots or areas. In one embodiment, the black, white, light gray, or silver printed dots or areas may have an average largest dimension in the plane of the film of less than or equal to one or more selected from the group of 200 microns, 100 microns, 75 microns, 50 microns, 40 microns, 30 microns, 20 microns, 15 microns, 10 microns, and 8 microns, and may have substantially the same size, or black dots or areas, or the black and silver printed dots or areas may be slightly larger than the printed white dots or areas. In one embodiment, the use of very small printed dots or areas prevents the viewer from distinguishing the dots individually and from actually seeing them to the naked eye.

In one embodiment, the light turning features comprise grooves in the film, and the visibility of the angular shadows is reduced by adding wide-angle reflective or wide-angle scattering features to one or more portions of the light turning features. For example, in one embodiment, a light scattering material, such as a light scattering ink, is added to the interior of the recess and fills or partially fills the recess. The carrier material (e.g., ink or uv curable thermoset material) may provide a higher refractive index to allow light propagating through the light turning element containing the light turning features to pass to the light scattering material (e.g., titanium dioxide particles, barium sulfate particles, polymer beads, etc.) to scatter (scatter, diffuse) the light at wider angles rather than undergoing "mirror-like" (specular) total internal reflection at the boundary between the groove material and the air within the groove. One advantage of this approach is that scattering can be added only to the grooves and not to the entire surface of the film by scratching or scraping the light scattering material into the grooves, if desired. By adding only light scattering to the grooves, the total internal reflection of the rest of the light diverting element can be maintained (or there is substantially no deviation of light propagating over the entire surface to another total internal reflection surface due to the absence of scattering material) and light can propagate further with less reduction in contrast due to the reflective scattering of ambient light over large surface areas. As in the above embodiments for the surface of the light turning features, the ink or scattering material may be white (diffuse reflection without significant absorption), silver (specular reflection, e.g., ink with reflective material nanoparticles), or light gray (partially diffuse and partially specular).

In one embodiment, the surface of the light turning features includes primary light turning features that redirect light to a desired output angle and secondary light scattering features that increase the angular or lateral scattering of incident light around the general angle of redirection. For example, in one embodiment, the tool used to create the light turning features has grooves with 40 degree angled surfaces. After the tool having the primary features with a smooth surface is fabricated, the tool may then be acid (or otherwise) etched to produce a micron-scale roughness (with undulations of about 2 microns to about 100 microns) on the grooves and the tool surface outside the grooves. The non-recessed regions may optionally be masked, for example with a photoresist material. In embodiments where the etching occurs over the entire surface (both on the grooved and non-grooved surfaces), a pressure sensitive adhesive (e.g., a hardcoat, touch screen film or protective film or other film for subsequent lamination onto the adhesive) may be applied over the grooved surface to effectively index match the undulations over the non-grooved areas, while still presenting air gaps in the grooved areas. By matching the refractive index (or reducing the refractive index difference) between the light-turning feature material and the binder, scattering due to etched surface relief in the non-recessed areas can be minimized, back scattering of ambient light reduced, and optical blurring of the displayed image reduced.

In another embodiment, the angle of the light turning features is modulated or contoured such that the angle of the surface varies along the length of the groove and the total reflection angle increases (reflected light is spread over a larger angle). These modulations or undulations can be created in the production of the tool by changing the relative depth of the diamond tool in a master element such as a master shim or metal roller (e.g., a copper or nickel alloy shim, metal roller, or other master die), or for example, by translating the diamond tool in a plane parallel to the surface of the shim (or metal roller) (or other master element surface) using fast servo. In any of these configurations, the diamond tool may move in a modulated or undulating manner relative to the shim or roller (or other main element) or the shim or roller (or other main element) may move in a modulated or undulating manner relative to the diamond tool. For example. In another embodiment, other tools, such as electron beam lithography, micro EDM, silicon V-groove etching or other etching methods, or additive or subtractive micro 3D printing methods, may be configured to create light turning features with modulation or undulations and/or create modulation or undulations in the master tool for making replicas or directly producing (e.g., via UV curing imprinting) light turning features and/or thin films. Methods of producing modulated or undulating linear features are known in the optical film industry and include methods such as those disclosed in U.S. Pat. No. 5,771,328 and U.S. Pat. No. 6,354,709.

Light redirection in light mixing regions

In one embodiment, a light transmissive material is added to the surface of the light guide in the light mixing region to create regions that direct or reflect light in sub-regions of the light mixing region to reduce angular shadowing. For example, in one embodiment, clear parallel stripes are printed on the surface of the light mixing region parallel to the optical axis of the light (or perpendicular to the array direction of the coupling lightguides) to create additional total internal reflection lightguides for light entering the sub-regions. These sub-areas can be used to independently direct a part of the light into the light-mixing area by "tapping" the light rays into the printed sub-areas, and the shape and length of the sub-areas determine the location to which the light is directed. The added light transmission region may be a thick line, a curved line, a dotted pattern, parallel regions such as lines that are parallel to each other, lines or features that are angled to each other, or lines or regions that direct more light toward light of an extra-width region (where it may be subsequently reflected toward the light emission region) or toward features that reflect light, so that light indirectly appears from a particular direction to be emitted from the extra-width region.

Multiplicity of reflecting surfaces between transverse edges

In one embodiment, the film-based light guide includes a plurality of reflective surfaces (e.g., linear reflective surfaces) in at least a portion of a light mixing region of the film-based light guide of the light emitting device between the lateral edges of the film. In an embodiment, one or more of the plurality of reflective surfaces direct light towards one or more lateral edges of the film by total internal reflection, and may provide additional spatial mixing of light and/or redirection of light from the coupling lightguides at a light mixing region in a direction parallel to the array direction of the array of coupling lightguides. The reflective surface may be disposed on or in a film-based light guide, such as on a film having an average thickness of less than 250 micrometers. The plurality of reflection surfaces may be formed, for example, by printing or evaporating a light transmissive material on one or more surfaces of a thin film-based light guide, by forming a film in such a manner that the film is scribed or cut to form cuts that may or may not pass through the film with a component in the thickness direction, or by embossing or forming a thin film with reflection surfaces that form a plurality of reflection surfaces.

In one embodiment, the plurality of reflective surfaces increases spatial luminance uniformity in the light mixing region and thus in the light emitting region in a direction parallel to the array direction of the array of coupling lightguides due to propagation of light from the light mixing region to the light emitting region. The multiple reflective surfaces can increase this uniformity by creating additional reflective surfaces with features in the thickness direction and in a direction orthogonal to the array direction of the array of coupling lightguides with a pitch greater than the pitch of the array of coupling lightguides. In one embodiment, one or more regions where adjacent coupling lightguides connect to the light-mixing region (when the coupling lightguides are laid flat and unfolded or before folding) comprise more than one selected from the group consisting of: 30 50, 100, 200, 500, 1,000 and 2,000 micrometers, and/or they comprise a facet having an angled portion greater than one selected from the group consisting of: at 5, 10, 15, 20, 30 and 45 degrees from perpendicular to the array direction of the array of coupling lightguides or parallel to the lateral edges of the coupling lightguides in two adjacent coupling lightguides. In one embodiment, the radius of curvature and/or the angular facet contributes to light and/or dark regions in the light emission area at the same pitch as the coupling lightguides in a direction parallel to the array direction of the coupling lightguides and the array, while the reflective surface reflects and mixes light from the coupling lightguides in the light mixing area in a direction parallel to the array direction of the array of coupling lightguides and increases the uniformity (e.g. luminance uniformity) in that direction.

In one embodiment, the film-based light guide includes a plurality of reflective surfaces in the light-mixing region, wherein the plurality of reflective surfaces are located between the core layer and the cladding layer of the film-based light guide, for example, by printing the plurality of reflective surfaces on a surface of the film in the light-mixing region, and laminating a pressure sensitive adhesive cladding layer on the plurality of reflective surfaces. In one embodiment, the light emitting device comprising a thin film based light guide with multiple reflective surfaces in the mixing region is a front light for a reflective spatial light modulator, such as a reflective LCD.

A film surface added to the light transmission region in the light guide mixing region to form multiple reflecting surfaces

In one embodiment, additional reflective surfaces (e.g., total internal reflection surfaces) are provided on at least one surface of the film in the light-mixing region of the light guide by adding light-transmissive material to the film surface or core layer to create additional reflective surfaces, the reflective surfaces having features in the thickness direction of the film that reflect light from the coupling light guide in a direction parallel to the array direction of the coupling array to the lateral edges of the light guide in the light-mixing region and/or to an excess width region toward the light-mixing region or light-emission region. The plurality of reflective surfaces may be printed stripes, ribs, linear regions, sub-regions, gratings, thick lines, curves, dot patterns of constant width or increasing or decreasing width towards the light emitting region, parallel regions such as lines, lines or features angled to each other, or lines or regions that direct more light towards the excess width regions of the film and/or the lateral edges of the film in the light mixing region. In one embodiment, the light transmissive material added to the thin film of the plurality of reflective surfaces formed in the light mixing region has a wetting contact angle (or average wetting contact angle) on the surface of the thin film in the light mixing region in a plane parallel to the array direction of the array of coupling lightguides that has a magnitude less than one selected from the group consisting of when the light transmissive material is hardened, cured, solidified, or otherwise fixed or used in a light emitting device, as measured using a contact angle goniometer: 50. 40, 30, 20, 10, 8 and 5 degrees.

In one embodiment, the difference in refractive index between the light transmissive material added to the film to define the plurality of reflective surfaces and the film material positioned in contact with the light transmissive material (e.g., the core material of the film) is less than one selected from the group consisting of: 0.001, 0.002, 0.005, 0.008, 0.01, 0.02, 0.05 and 0.1. In one embodiment, the refractive index of the light-transmissive material added to the thin film is less than 0.001, 0.002, or 0.005 greater than the refractive index of the thin film material positioned in contact with the light-transmissive material, and/or the refractive index of the light-transmissive material added to the thin film is less than 0.01, 0.001, 0.002, or 0.005 less than the refractive index of the thin film material positioned in contact with the light-transmissive material. In one embodiment, the index of refraction of the light transmissive material added to the film is substantially index matched to the film material positioned in contact with the light transmissive material.

The inner light-guiding edge forms a plurality of reflecting surfaces

In one embodiment, a plurality of reflective surfaces (e.g., total internal reflection surfaces) are formed in an interior region of the film in the light mixing region of the light guide by dicing, cutting, etching, ablating, removing material, embossing, or molding (e.g., injection molding), the reflective surfaces having features in the thickness direction of the film that reflect light from the coupling light guides in a direction parallel to the array direction of the coupling array toward lateral edges of the light guide in the light mixing region, and/or toward an area of excess width of the light mixing region or light emission region. In one embodiment, the internal light reflecting surface extends through the thickness of the core region of the film, through an average portion of the film thickness, the average wave portion being greater than one selected from the group consisting of: 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, and 90 percent of the film thickness at the inner reflective surface, or an average portion extending through the film thickness that is less than one selected from the group consisting of: 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, and 90 percent film thickness of the internal reflective surface. In an embodiment, the plurality of reflective surfaces in the inner region of the film (e.g., within the core layer or region) form lateral reflective edges that reflect light toward the lateral edges of the film in the light mixing region, thereby increasing the uniformity of light emitted from the film in the light emission region in a direction parallel to the array direction of the array of coupling lightguides.

Position of multiple reflecting surfaces

In one embodiment, a plurality of reflective surfaces are positioned at least in a portion of a light mixing region of a thin film based light guide. In one embodiment, all or a portion of the plurality of reflective surfaces extend into the light-emitting area. In one embodiment, at least a portion of the plurality of reflective surfaces are positioned along the film between the coupling light guide and the light-emitting region of the film. In another embodiment, at least a portion of the plurality of reflective surfaces extend into a lateral edge region of the film in a light-mixing region of the film that extends beyond a light-emitting region of the film. In further embodiments, at least a portion of the plurality of reflective surfaces are located on a first surface of the film-based light guide that is closer to the reflective spatial light modulator, on a second surface of the film-based light guide that is further from the reflective spatial light modulator, and/or on two opposing extended surfaces of the film-based light guide. In embodiments having groups of multiple reflective surfaces on different locations, regions, or opposing surfaces, different groups may have different reflective surface characteristics, such as added light transmissive material type, internal light directing edge type, pitch, height, depth, width, cross-sectional shape, orientation, or curvature. In one embodiment, all or a part of the plurality of reflection surfaces is located on a first part of the light mixing region folded behind a second part of the light mixing region different from the first part or folded behind the light emission region in a thickness direction of the film of the second part of the light mixing region (or a reflective spatial light modulator).

Orientation of multiple reflecting surfaces

In one embodiment, the plurality of reflective surfaces are oriented substantially in the same plane parallel to the surface of the film in the light mixing region. In one embodiment, the plurality of reflective surfaces are oriented in such a way that a portion of the plurality of reflective surfaces has features parallel to a thickness direction of the film. In another embodiment, all or a portion of the plurality of reflective surfaces are oriented at a first reflective surface orientation angle in a plane perpendicular to the thickness direction of the film, the first reflective surface orientation angle making one of the following group of angles with a direction from perpendicular to the array of coupling lightguides: 0 degrees, less than 5 degrees, less than 10 degrees, less than 20 degrees, greater than 5 degrees, greater than 10 degrees, greater than 20 degrees, greater than 30 degrees, and greater than 45 degrees. For example, in one embodiment, the plurality of reflective surfaces are printed lines of light transmissive material on the surface of the thin film based light guide in a light mixing region that is oriented parallel to a direction perpendicular to the alignment direction of the coupling light guide and the first reflective surface orientation angle is 0 degrees. In another embodiment, all or a portion of the plurality of reflective surfaces are oriented in a plane parallel to the thickness direction of the film at a second reflective surface orientation angle that is one of the following group of angles from a direction normal to a surface of the film-based light guide or a core layer of the film: 0. degree, less than 5 degrees, less than 10 degrees, less than 20 degrees, greater than 5 degrees, greater than 10 degrees, greater than 20 degrees, greater than 30 degrees, and greater than 45 degrees. For example, in one embodiment, the plurality of reflective surfaces are inner light guide edges formed by slitting a surface of the core layer of the film-based light guide in the light mixing region, wherein the slits are oriented parallel to a direction perpendicular to the surface of the core layer of the film-based light guide, with a second reflective surface orientation angle of 0 degrees. In one embodiment, the plurality of reflective surfaces are linear and include curved or angled regions such that two or more portions of the linear reflective surfaces are oriented at different orientation angles.

Number of multiple reflecting surfaces

In one embodiment, the film-based light guide includes a plurality of reflective surfaces in a light mixing region between the lateral edges of the film that is greater than one selected from the group consisting of: 1. 2, 5, 10, 20, 50, 75, 100, 150, 200, 500, 1,000, and 5000. In one embodiment, the number of the plurality of reflective surfaces divided by the number of the coupling lightguides is greater than one selected from the group consisting of: 5. 10, 20, 50, 100 and 500.

Pitch of reflecting surface

In one embodiment, a pitch of the plurality of reflective surfaces in a direction parallel to the array direction of the array of coupling lightguides and perpendicular to a thickness direction of the core layer in the light mixing region of the thin film based lightguide is less than one or more pitches selected from the group consisting of: less than the pitch of the array of coupling lightguides, less than one fifth of the pitch of the array of coupling lightguides, less than 5 millimeters, less than 3 millimeters, less than 1 millimeter, less than 0.5 millimeters, less than 0.3 millimeters, less than 0.1 millimeters, less than 75 micrometers, less than 50 micrometers, less than 40 micrometers, and less than 30 micrometers.

Width of multiple reflecting surfaces

As used herein, the average width or width of each of the plurality of reflective surfaces is defined in a direction parallel to the array direction of the array of coupling light guides and perpendicular to the thickness direction of the core layer. In one embodiment, an average width or width of each of the p plurality of reflective surfaces is constant in a direction orthogonal to an array direction of an array of coupling light guides across the plurality of reflective surfaces in the thin-film light guide-based light mixing region. In one embodiment, an average width or width of each of the plurality of reflective surfaces is less than a pitch of the array of coupling lightguides, less than one fifth of the pitch, less than 5 millimeters, less than 3 millimeters, less than 1 millimeter, less than 0.5 millimeters, less than 0.3 millimeters, less than 0.1 millimeters, less than 75 micrometers, less than 50 micrometers, less than 40 micrometers, and less than 30 micrometers in all or at least a portion of the light mixing region. In one embodiment, in all or part of the light mixing region, an average width or width of each of the plurality of reflective surfaces is less than one selected from the group consisting of: 1. 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, 0.01, 0.005, 0.001 times the width of the light-mixing region in a direction parallel to the array direction of the array of coupling lightguides and perpendicular to the thickness direction of the core layer of the light-mixing region of the thin-film based lightguide. In another embodiment, in all or part of the light mixing region, an average width or width of each of the plurality of reflective surfaces is less than one selected from the group consisting of: 1. 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, 0.01, 0.005, 0.001 times the average width of the coupling lightguides in a direction parallel to the array direction of the array of coupling lightguides and perpendicular to the thickness direction of the core layer of the light mixing region of the thin film-based lightguide. In another embodiment, in all or part of the light mixing region, the average width w0 of each of the plurality of reflective surfaces and the average pitch p0 of the plurality of reflective surfaces are set such that w0 divided by p0 results in one selected from the group consisting of: 1. 0.7, 0.5, 0.4, 0.3, 0.2, 0.1 and 0.05. In one embodiment, the plurality of reflective surfaces are printed lines of light transmissive material on the core layer of the thin film based light guide, wherein the printed lines have an average width w0 and an average pitch p0 in a direction parallel to the array direction of the array of coupling light guides and perpendicular to the thickness direction of the core layer in the light mixing region of the thin film based light guide, such that the duty cycle dc of the lines is equal to w0 divided by p0. In one embodiment, the duty cycle of the line is less than one selected from: 1. 0.7, 0.5, 0.4, 0.3, 0.2, 0.1 and 0.05.

Multiple lengths of reflective surface

As used herein, the average length or length of each of the plurality of reflective surfaces is defined in a direction perpendicular to the array direction of the array of coupling light guides and perpendicular to the thickness direction of the core layer of the film. In one embodiment, an average length or length of each of the plurality of reflective surfaces in the light mixing region of the film-based light guide is limited to the light mixing region of the film-based light guide. In an embodiment, lengths of the plurality of reflective surfaces extend into the one or more coupling light guides and/or into the light emission area. In another embodiment, the average length or length of each of the plurality of reflective surfaces is less than one selected from the group consisting of: 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.1 times the length of the light-mixing region in a direction perpendicular to the array direction of the array of coupling lightguides and perpendicular to the thickness direction of the core layer in the light-mixing region of the film-based lightguide. In another embodiment, the average length or length of each of the plurality of reflective surfaces is greater than one selected from the group consisting of: 0.8, 0.7, 0.6, 0.5, 0.4, and 0.3 times the length of the light-mixing region in a direction perpendicular to the array direction of the array of coupling-in light guides and perpendicular to the thickness direction of the core layer in the light-mixing region of the thin-film based light guide. In one embodiment, the average length or length of each of the plurality of reflective surfaces in the light mixing region of the film-based light guide is greater than one selected from the group consisting of: 1. 2, 4, 5, 10, 20, 30, 40, 50, 60, 70, 80, and 90 millimeters, and/or less than one selected from the group consisting of: 2. 4, 5, 10, 20, 30, 40, 50, 60, 70, 100 and 200 millimeters. In another embodiment, the average length or length of each of the plurality of reflective surfaces is greater than one selected from the group consisting of: 2. 4, 5, 8, 10, 15, 20, 30, 40, 50 and 100 times the width of the plurality of reflective surfaces (in a direction parallel to the array direction of the array of coupling light guides and perpendicular to the thickness direction of the core layer of the light guides) in the light mixing region.

Height of multiple reflecting surfaces

As used herein, the average height or height of each of the plurality of reflective surfaces is defined in a direction parallel to the thickness direction of the core layer of the light guide. In one embodiment, the average height or height of each of the plurality of reflective surfaces in the light-mixing region of the thin-film based light guide is limited within the core layer of the thin-film based light guide in the light-mixing region of the thin-film based light guide. In another embodiment, the average height or height of each of the plurality of reflective surfaces is less than one selected from the group consisting of: 0.6, 0.5, 0.4, 0.3, 0.2, 0.015, 0.1, 0.07, 0.05, and 0.02 times the thickness of the core layer of the film in the light-mixing region in a direction parallel to the thickness direction of the core layer in the light-mixing region of the thin-film based light guide. In another embodiment, the average height or height of each of the plurality of reflective surfaces is one or more selected from the group consisting of: less than 50 microns, less than 20 microns, less than 10 microns, less than 5 microns, less than 1 micron, greater than 0.2 microns, greater than 0.3 microns, greater than 0.5 microns, greater than 1 micron, greater than 2 microns, greater than 3 microns, and greater than 5 microns in a direction parallel to a thickness direction of the core layer in a light-mixing region of the film-based light guide.

Cross-sectional shape of multiple reflecting surfaces

In one embodiment, a cross-sectional shape of each of the plurality of reflective surfaces in a cross-sectional plane parallel to the array direction of the array of coupling light guides and parallel to the thickness direction of the core layer of the film-based light guide in the light mixing region comprises all or a portion of one or more shapes selected from the group consisting of: circular, oval, square, rectangular, triangular, parallelogram, truncated triangular, isosceles trapezoid, acute trapezoid, quadrilateral, and polygonal. In one embodiment, the lateral walls of the plurality of reflective surfaces are oriented at an angle that is less than one of 30 degrees, 20 degrees, 10 degrees, 8 degrees, 5 degrees, and 2 degrees from a direction perpendicular to the surface of the core layer in the light mixing region of the thin-film based light guide. In one embodiment, the plurality of reflective surfaces are defined by a material added to a core layer or surface of the thin film based light guide, and a total cross-sectional area of the plurality of reflective surfaces (e.g., the plurality of linear light reflective surfaces) is selected from one of the following group: 50%,40%,30%,20%,15% and 10% of the total continuous cross-sectional area of the core layer of the thin film directly below (or above) the area defined by the plurality of reflective surfaces in a plane that includes the thickness direction of the film and that is parallel to the array direction of the array of coupling lightguides. In one embodiment, a surface of the plurality of reflective surfaces opposite the core layer of the thin film based light guide is parallel to a surface of the core layer at the plurality of reflective surfaces in the light mixing region. In one embodiment, a cross-sectional shape of each of the plurality of reflective surfaces in a cross-sectional plane parallel to the array direction of the array of coupling light guides and parallel to a thickness direction of a core layer of the thin film based light guide in the light mixing region is curved, the shape of which is a line of material printed on the surface with a wetting contact angle of less than 40 degrees.

Losses due to the addition of multiple reflecting surfaces

In one embodiment, the total loss of light propagating out of the thin film based light guide having a plurality of reflective surfaces in the light mixing region is less than one selected from the group consisting of: 50%, 40%, 30%, 20% and 10% of the light flux entering the light-mixing region is determined by collecting light emitted from the surface of the film in the light-mixing region in an integrating sphere and comparing the light entering the light-mixing region by cutting the film at the end of the coupling light guide of the film at the beginning of the light-mixing region. In one embodiment, the loss due to the addition of the plurality of reflective surfaces is primarily due to the end faces of the plurality of reflective surfaces (as the plurality of reflective surfaces extend from the coupled-in light guide to the light-emitting region) having an orientation angle in the light-mixing region, one component of the angle being in a thickness direction of a core layer of the thin-film based light guide and one component being in a direction parallel to an array direction of the array of coupled-in light guides. The angular or physical extent of the end faces of the plurality of reflective surfaces relative to the angular or physical extent of light in a plane parallel to the direction of alignment of the array of coupling lightguides and parallel to the thickness direction by the core layer in the film-based lightguide results in light loss because the end faces reflect a portion of the light back into the coupling lightguides and/or reflect the core layer (and/or film) in the light-mixing region (and thus, for example, exit the film-based lightguide before the designed light-emitting region with the light extraction features and/or before the reflective spatial light modulator). In general, the greater the physical and/or angular extent of the end faces of the multiple reflective surfaces, the more light is directed out of the core layer and/or film in the light mixing region of the film-based light guide.

In one embodiment, the plurality of reflective surfaces are total internal reflection surfaces that increase the uniformity of light exiting the light emission region by reflecting a portion of the incident light from the core layer toward the lateral edges of the film in the light mixing region, the larger the end face of the end of the plurality of reflective surfaces, the greater the degree of angle reflected by the end face, and the greater the light loss. In some embodiments, it is desirable to increase light mixing by increasing the area of the lateral surfaces of the plurality of light reflecting surfaces that reflect light toward the lateral edges of the film in the light mixing region and minimizing the area of the end faces of the plurality of light reflecting surfaces to reduce light loss. For some substantially linear multiple reflection surfaces, the lateral surface area of the multiple reflection surfaces is twice the length of the multiple reflection surfaces times the height of the multiple reflection surfaces, and the end face area of the end face of the reflection surface is the height of the multiple reflection surfaces times the width of the multiple reflection surfaces (assuming a constant cross-section along the length in the light mixing region from the coupling light guide to the light emission region). Therefore, in the present embodiment, it is possible to increase the mixing of light and minimize the light loss by increasing the lengths of the plurality of reflection surfaces and decreasing the widths of the plurality of reflection surfaces. In some embodiments, the height of the plurality of reflective surfaces is reduced to reduce light loss by reducing the surface area of the plurality of reflective surfaces, and the length of the plurality of reflective surfaces is increased in order to increase light mixing. In an embodiment, an average length of the plurality of reflective surfaces divided by an average width of the plurality of reflective surfaces is greater than one selected from the group consisting of: 5. 10, 20, 50, 80, 100, 500, 1,000, 5,000, 10,000, 15,000, 150,000 and 200,000.

In another embodiment, the light mixing region includes an internal light directing edge that redirects a portion of incident light by total internal reflection to reduce angular shadowing. These inner light guiding edges may be made, for example, by laser cutting, die stamping, laser ablation, etc., and may be configured as discussed elsewhere herein. In one embodiment, the inner light guiding edge reflects more light towards the extra-width region or towards features that reflect the light (e.g., other inner light guiding edges, lateral film edges, or light scattering materials), thereby indirectly appearing to originate from the extra-width region from a particular direction and reducing the visibility of angular shadows.

Adding a separate diffusing layer or material

In one embodiment, one or more layers of a light emitting display or light emitting device include a diffusing layer or film optically coupled to at least one of a light mixing region, a light guiding region, and a light emitting region. The diffusing layer or film may spread more light laterally into the excess angular width region, and then may reflect back into the light emitting region from edges or features within the excess width region (e.g., internal light guiding edges, lateral edges, light scattering material, or light reflecting or scattering surfaces within the excess width region), or it may redirect light rays so that it indirectly appears to be emitted from the out-of-width region from a particular angle. In this embodiment, the diffusing layer or material may direct light to a light mixing region outside the excess width region, an element or feature of the light emitting region of the light guiding region (e.g., an internal light guiding edge, a light scattering material, or a light reflecting or scattering surface) where it is reflected from a location of the element or feature to a direction that is the same as the location and direction of light if the light emanates from the excess width region and propagates toward the light emitting region. In one embodiment, one or more diffusing layers or films are located on or between two or more elements, films or layers selected from the group consisting of: a protective overcoat with a hardcoat, a touch screen film, a light turning film comprising light turning features, an adhesive layer, a cladding layer on the visible side of the display, a film-based light guide, a core layer of the film-based light guide, a cladding layer on the display side of the core layer of the film-based light guide, and a reflective spatial light modulator. In one embodiment, the in-situ diffusing layer in the light emitting device or display has an angular full width at half maximum intensity of less than 0.5, 1, 2, 3, 4, 5, 7, 10, 15, or 20 degrees, as measured with a photometer measuring 1/3 degrees or less, e.g., from a Konika Menten colorimeter CS-160, using a laser light of 532 nanometers (divergence less than or equal to 1.5 milliradians) perpendicularly incident to the surface of the diffusing film or diffusing layer. In one embodiment, the diffuser film or layer is measured before being integrated with or after being extracted from the light emitting device or display.

Adding additional turning features in the light-emitting region that differ in refractive index from adjacent regions

In one embodiment, the light emitting region of the film-based light guide includes light turning features in the form of grooves, dimples, holes or surface relief in one or more cladding layers and/or a core layer, and an adhesive is laminated, printed, coated or otherwise applied to the light turning features, wherein the refractive index between the adhesive material and the surface material of the one or more cladding layers and/or the core layer at the sodium wavelength is greater than 0.005,0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and 0.1, respectively. In this embodiment, by maintaining the refractive index difference between the materials at the interface, the first portion of light at higher angles will undergo total internal reflection, which may be directed to the excess width region or indirectly appear to originate from the excess width region (as described in the preceding paragraphs). Large refractive index differences, such as between a common polymer material film or substrate material and air, may result in excessive scattering or backscattering, thereby reducing the contrast of the display. By using a smaller refractive index difference, incident light of a large angle may be selected to be totally internally reflected or refracted to or appear to come from the excess width region, such as by reflecting (e.g., internal light guiding edges, light scattering material or light reflecting or scattering surfaces) from elements or features of the light guiding or light emitting region outside the excess width region corresponding to the same position and direction of light as the light of the light emitted from the excess width region and propagating toward the light emitting region.

Internal light-guiding edges or guides for guiding light in light-guiding or light-emitting regions

In one embodiment, the light guide region and/or the light emission region include one or more internal light guiding edges and/or light transmission guides (e.g., printed sub-regions of light transmissive material as disclosed above with respect to the light mixing region) to reflect light into specific spatial locations with specific angular profiles, such that they reflect more light toward the extra-width region (which may then be reflected toward the light emission region) or reflective features (e.g., other internal light guiding edges, lateral film edges, or light scattering material) such that it appears indirectly that light originates from the extra-width region. For example, in one embodiment, a cut is made through the core layer (and optionally one or more cladding layers) in the light-emitting region to direct light output near the outer coupling light guide to an excess width region along the array direction of the array of coupling light guides. These cuts may form guides that direct light into the excess width regions, and the same cuts or different cuts may be made to reflect light from locations within the excess width regions back toward the light emission region.

Increasing the spacing or gap between coupled light guides

In one embodiment, the two or more coupling lightguides comprise a space or gap between the two or more coupling lightguides where they connect to the lightguide region, the light mixing region or the light emitting region. In one embodiment, for a particular thin film based light guide, the width of the particular coupling light guide and the number of coupling light guides are used to match the output area of the light source (e.g., light emitting diode), and by spacing the coupling light guides apart in the array of coupling light guides, the light output from the array of coupling light guides can extend further in the width direction (the array direction of the coupling light guides) when entering the light mixing area, the light guide area, or the light emission area, and reduce the visibility of angular shadows.

The region of excess width being a larger light-emitting region or display region

In one embodiment, the excess width region includes a portion of the light emitting region. For example, the total width of the coupling lightguides and the width of the light mixing area may be the same in the array direction of the array of coupling lightguides, and they may both be smaller than the width of the light emitting area or of a display comprising the light emitting area. For example, in one embodiment, the light emitting area of the film-based light guide is a front light for a reflective spatial light modulator, wherein the reflective spatial light modulator is octagonal, and is a display for a watch, wherein the width of the light emitting area in the direction of the array of coupling light guides is greater than the total width of the array of coupling light guides. This can be done, for example, to easily fold the light-mixing region behind the reflective spatial light modulator so that the fold is along one of the eight sides of the display. Where the excess width includes a portion of the light-emitting region, angular shading reduction techniques may be used to direct or reflect light to specific spatial locations within the light-emitting region or the excess width region having a specific angular profile such that they reflect more light toward different regions of the excess width region or toward features that reflect light (e.g., other internal light-directing edges, lateral film edges, or light-scattering materials) such that the light indirectly appears to originate from the excess width region. As with the light mixing or guiding regions, the light emitting region may have an inner light guiding edge, a lateral film edge, a printed guide plate or a light scattering material that reflects or guides light to an excess width region representing an area of the array of coupling lightguides over which the display or light emitting region extends in the array direction of the array of coupling lightguides. In one embodiment, the shape of the display or light emitting area is a shape selected from one or more of the following: circular, oval, square, rectangular, triangular, parallelogram, pentagonal, hexagonal, heptagonal, octagonal, nonagonal, decagonal, undecengonal, dodecagonal, tridecapental, tetradecapental, pentadecagonal, polygonal, and combinations of two or more polygons. In another embodiment, the total width of the array of coupling lightguides in the array direction divided by the active area of the reflective spatial light modulator, the maximum width of the active area of the display or the light emission area in the array direction of the array of coupling lightguides is less than one of the group: 95%,90%,85%,80%,75%,70%,65%,60%,50%,40%,30% and 20%. In another embodiment, the maximum width of the active area, the active area of the display or the light emitting area of the reflective spatial light modulator in the array direction of the array of coupling lightguides is larger than the total width of the array of coupling lightguides in the array direction by one selected from the group consisting of: 2. 5, 7, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, 100, 150, 300, 500, and 1000 millimeters. The method for reducing the visibility of angular shadows may also be used to direct light into an excess width area of the light emission area, which may correspond to a larger display width than the total width of the array of coupling light guides in the display in the array direction. Thus, for example, an internal light guiding edge, a scattering region, a printed guide of light transmissive material, adding a wide angle reflective scattering feature in the light turning feature element, adding a wide angle reflective or wide angle light scattering feature to the light turning feature, adding/increasing the amount of scattering in the region of the light turning feature, redirecting light in the light mixing region, adding a separate diffusing layer or material, adding an additional turning feature in a light emitting region with a different index of refraction than the adjacent region, using an internal light guiding edge or guide to guide light to a particular spatial location with a particular angular profile, or increasing the spacing or gap between coupling light guides to guide light to a wider light emitting region or a wider display in the array direction of the array of coupling light guides can be used.

Illuminating the light-emitting area from many directions

In one embodiment, the light emitting area and/or the display is illuminated from a coupling light guide or light mixing area extending from the light emitting area, the opposite side of the light guide area or the display, the adjacent side or along the light emitting area or the light guide area of a curved or other side, such that the coupling light guide and/or the light mixing area along these sides is folded behind the display. For example, in one embodiment, the watch includes an octagonal display, and the light guides have octagonal light emitting areas, where the light mixing regions of the film extend from the light emitting area (or the light guide area including the light emitting area) along four adjacent sides, and fold behind the display at different fold angles, where each light mixing region may include an array of coupling light guides, optionally folded behind the display at an angle corresponding to the side of the display. Similarly, a circular or oval light emitting area and/or display may have an arcuate portion of light mixing area or portion of coupling light guide along the light emitting area or light guide area that may be folded and optionally stacked behind an optional single light source, such as a light emitting diode.

In another embodiment, the light emitting area and/or the display is illuminated from an elongated coupling light guide or one or more elongated light mixing areas extending from opposite sides of the light emitting area or the display, adjacent sides or along the light emitting area or light guide area of a bend or other side, such that the coupling light guide and/or light mixing areas along these sides are stretched and optionally folded behind the display. For example, in one embodiment, the thin film based light guide includes a high refractive index silicone based core layer, wherein one or more portions of the thin film based light guide are stretched around the back surface of the reflective spatial light modulator and the light emitting area is positioned over the active area of the reflective spatial light modulator. In this example, the stretched portions may be light mixing regions or coupling lightguides, and may be subdivided into an array of coupling lightguides or a subset of an array of coupling lightguides, respectively, and optionally folded and stacked such that their ends define a light input surface positioned to receive light from a light source such as a light emitting diode.

Position of film-based light guide

In one embodiment, the core region of the film-based light guide is positioned between two layers selected from the group consisting of: a hardcoat substrate, layer or adhesive; an anti-glare or anti-reflective layer, substrate, or adhesive; a color filter material, layer, substrate or adhesive; a first cladding layer of light guides; a second cladding layer of the light guide; a clad substrate or adhesive; a film-based light guide adhesive; an electro-optic layer (e.g., a liquid crystal layer or an electrophoretic layer); a viewer-side substrate of an electro-optic layer; a substrate for the electro-optic layer on the non-viewer side; an adhesive or substrate for the electro-optic layer; a reflective material, film, layer or substrate or a binder for the reflective layer; polarizer layer substrates or polarizer adhesives; a light redirecting layer; a light extraction functional sheet; impacting the protective layer; an inner coating; a conformal coating; a circuit board; a flexible connector; a thermally conductive film, layer (e.g., a stainless steel, copper or aluminum foil layer), substrate or adhesive; a sealant layer, film substrate or adhesive; an air gap layer; an isolation layer or a substrate for an isolation layer; a conductive layer (transparent or opaque), substrate or adhesive; an anode layer, substrate, or anode layer binder; a cathode layer, a substrate or binder for the cathode layer; an active matrix layer, a substrate of the active matrix layer or an adhesive; a passive matrix layer, a substrate of the passive matrix layer or an adhesive; a touch screen layer, a touch screen substrate, or a touch screen layer adhesive. In another embodiment, a thin film based light guide is used as one or more of the above layers in addition to propagating light under waveguiding conditions.

In one embodiment, a thin film based light guide is positioned between a color filter layer and an electro-optic layer such that parallax effects due to high angle light are minimized (resulting in higher contrast, greater resolution, or higher brightness). In another embodiment, the thin film based light guide is a substrate of a color filter material or layer. In another embodiment, the film-based lightguide is a substrate for an electro-optic material or layer.

In one embodiment, the distance between the light extraction features and the color filters in a multicolor display is minimized by positioning the thin-film based lightguide within the display or using the thin-film based lightguide as a substrate for the materials or layers of the display (e.g., a substrate for a color filter layer, a transparent conductor layer, an adhesive layer, or a layer of electro-optic material). In one embodiment, the light emitting device includes a plurality of light-absorbing adhesive regions adhered to one or more layers of a display or film-based lightguide (e.g., on a cladding layer of the film-based lightguide or on a layer of electro-optic material).

In one embodiment, a light emitting device includes a film-based light guide and a force-sensitive touch screen, where the film-based light guide is sufficiently thin to allow the force-sensitive touch screen to function by finger pressure on a display.

In one embodiment, a thin film based light guide front light is disposed between a touch screen film and a reflective spatial light modulator. In another embodiment, a touch screen film is disposed between a thin film based light guide and a reflective spatial light modulator. In another embodiment, the reflective spatial light modulator, the film-based light guide front light, and the touch screen are film-based devices, and the films may be laminated together. In another embodiment, a light transmissive conductive coating for a touch screen device or display device is coated on a film-based light guide front light. In another embodiment, the film-based light guide is physically coupled to a flexible electrical connector of a display or touch screen. In one embodiment, the flexible connector is a "flexible cable," "flex cable," "ribbon cable," or "flexible harness," including rubber films, polymer films, polyimide films, polyester films, or other suitable films.

In one embodiment, a reflective display includes one or more film-based lightguides disposed within or proximate to one or more regions selected from the group consisting of: a region between the touch screen layer and the reflective light-type modulation pixels, a viewing-side region of the touch screen layer, a region between the diffusion layer and the reflective light-type modulation pixels, a viewing side of the diffusion layer in the reflective display, a region between the diffusion layer and the light-modulation pixels, a region between the diffusion layer and the reflective elements, a region between the light-modulation pixels and the reflective elements, a component or a substrate of the light-modulation pixels, a viewing side of the reflective display, between the color filter and the spatial light-modulation pixels, a viewing side of the color filter, between the color filter and the reflective elements, a substrate for the color filter, a substrate for the light-modulation pixels, between the touch screen substrate, a region between the protective lens and the reflective display, a region between the light extraction layer and the light-modulation pixels, a viewing-side region of the light extraction layer, a region between the adhesive and a component of the reflective display; and the area between two or more components of a reflective display, as is known in the art. In the foregoing embodiments, the film-based lightguide may include volumetric or light extraction features on one or more surfaces of the lightguide, and the lightguide may include one or more lightguide regions, one or more cladding regions, or one or more adhesion regions.

In one embodiment, the thin-film based light guide is folded around a first edge of an active area of the reflective spatial light modulator behind the reflective spatial light modulator, and one or more selected from the group consisting of: the touch screen connector, the touch screen film substrate, the reflective spatial light modulator connector and the reflective spatial light modulator film substrate are folded to the rear of a first edge, a second edge substantially orthogonal to the first edge or an edge opposite the first edge. In the foregoing embodiments, a portion of the light guide region, the light mixing region, or the coupling light guide includes a folded bend region and may extend beyond the reflective spatial light modulator flexible connector, the reflective spatial light modulator substrate, the touch screen flexible connector, or the touch screen flexible substrate.

Light orientation within a display

In one embodiment, a thin-film based light guide illuminator illuminates a spatial light modulator at a display illumination angle (from a viewer side, from a side opposite the viewer, or from within the display) within a layer or material adjacent to a layer of electro-optic material or spatial light modulator in a first illumination plane. As used herein, a display illumination angle is defined as the angle at which the peak intensity from the surface normal of a spatial light modulating component or layer (on the viewer side) is measured (or calculated) within the layer or material adjacent to the spatial light modulating component or layer in a first illumination plane (e.g., an electro-optic element of an electrophoretic display or a liquid crystal layer in a liquid crystal display). In one embodiment, the display illumination angle is less than one selected from the group consisting of: 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees and 5 degrees. In one embodiment, the first illumination plane is parallel to the extension direction of the coupling light guide. In another embodiment, the first illumination plane is perpendicular to the extension direction of the coupling light guide.

In another embodiment, the film-based light guide illumination device illuminates the color filter layer or material at a color filter illumination angle (from the viewer side, the side opposite the viewer, or from within the display) inside of the layer adjacent to the color filter layer or material in a first illumination plane. A color filter illumination angle is defined as the angle at which the peak intensity from the surface normal of the filter material or layer is measured (or calculated) within the layer or material (on the viewer side) adjacent to the filter material or layer in a first illumination plane (e.g., the red, green, and blue arrays of color filter materials in an electrophoretic display). In one embodiment, the color filter illumination angle is less than one of the angles selected from: 70 degrees, 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees, and 5 degrees.

As used herein, the light guide illumination angle in the first illumination plane is the peak angular intensity of light exiting the film-based (due to extraction features) light guide from the normal to the surface of the light emitting device (or normal to the surface of the film-based light guide) measured or calculated in the core layer (or within the cladding layer, if present). In one embodiment, the lightguide illumination angle is less than one of the angles selected from: 70 degrees, 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees, and 5 degrees. In one embodiment, the light guide illumination angle is the same as the display illumination angle or the color filter illumination angle.

In another embodiment, the angular bandwidth illumination angle is the full angular width at half maximum intensity of light exiting the film-based light guide due to extraction features measured or calculated in the core layer (or cladding layer, if present) in a first illumination plane from the normal to the light-emitting device surface. In one embodiment, the angular bandwidth illumination angle is less than one selected from the group consisting of: 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees and 5 degrees.

By reducing the full angular width at half maximum intensity of light exiting the thin film based lightguide due to the extraction features, or redirecting the light using the extraction features such that the lightguide illumination angle, the display illumination angle, or the color filter illumination angle is near zero degrees, the resolution, contrast, and/or brightness of the display may be improved by reducing the higher angle light that may pass through two light modulating pixels or color filters in the display.

In one embodiment, a light emitting device includes a light collimating optical element that reduces a full angular width of light exiting a film-based light guide at a half maximum intensity by reducing the full angular width at the half maximum intensity of light incident to one or more light extraction functions. In another embodiment, the thickness of the thin film based light guide is increased to allow greater collimation in the plane perpendicular to the film surface by using larger light collimating optical elements to direct light into the light input surface. In another embodiment, at least one of the size, spacing, shape, depth, width, location, and density of the light extraction features is adjusted to reduce the full angular width at half maximum intensity of light exiting the thin film based light guide or light, or to direct the light guide illumination angle, display illumination angle, or color filter illumination angle to near zero degrees.

In one embodiment, light extraction features on a film-based light guide define concave (concave) or convex (convex) features on the film surface, and a light absorbing material on the viewer side of the concave or convex features absorbs stray light that is directly reflected, refracted, or diffracted from the features, thereby absorbing light that does not pass through the display that would reduce the contrast of the display. In an embodiment, the light extraction features are refractive surfaces, diffractive surfaces, total internal reflection surfaces or a combination of one or more of these surfaces. In one embodiment, the light extraction features are defined by a plurality of facets, for example two, three or four linear facets per groove, linear feature, two-dimensionally arranged feature or three-dimensionally arranged feature. In another embodiment, the light extraction features are defined in a separate layer or material and optically coupled to the lightguide. In one embodiment, a light absorbing material having a first refractive index that is less than the refractive index of the core material is optically coupled to the core or cladding layer such that higher angles of light are absorbed by the light absorbing material. In one embodiment, the higher angle light is light propagating within a core region of the light guide at an angle relative to an optical axis of the light guide that is greater than one selected from the group of 40 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, and 85 degrees.

In one embodiment, illumination from two or more sides of the light-emitting region of the film-based light guide interacting with the light extraction features reduces the full angular width at half maximum intensity of light exiting the film-based light guide, or directs the illumination angle of the light guide, the illumination angle of a display, or the illumination angle of a color filter to near zero degrees.

In another embodiment, the adhesive layer adjacent to the recessed light extraction features allows for a low index of refraction gas or air cavity that causes total internal reflection of light propagating within the lightguide (or the material or layer in which the extraction features are formed) at the interface between the lightguide (or the material or layer in which the extraction features are formed) and the gas or air cavity at the light extraction features. For example, in one embodiment, a pressure sensitive adhesive layer is laminated to a film-based lightguide that includes a fluted cavity in a core region of the lightguide such that an air gap exists at the extraction feature-air cavity interface for total internal reflection of light within the lightguide. In another embodiment, the thickness of the adhesive layer adjacent to the one or more cavity-based light extraction features is less than one selected from the group of 2 times, 1.5 times, 1, 0.75 times, 0.5 times, 0.2 times, and 0.1 times the depth of the light extraction features in the thickness direction of the film. In another embodiment, the adhesive adjacent to the one or more cavity-based light extraction features has a thickness less than one selected from the group of 200, 175, 150, 125, 100, 75, 60, 50, 40, 30, 20, and 10 microns. In another embodiment, the cladding layer adjacent to the one or more cavity-based light extraction features has a thickness less than one selected from the group of 200, 175, 150, 125, 100, 75, 60, 50, 40, 30, 20, and 10 microns.

In one embodiment, a full angular width at half maximum intensity of light from the light source that is emitted from the coupling light guide in a first plane including a thickness direction of the film is greater than a full angular width at half maximum intensity of light from the light source that is emitted from the coupling light guide in a second plane including a direction perpendicular to the thickness direction. In one embodiment, the light output profile from the light source is rotated such that the collimation or plane including the lowest divergence rotates or switches within the light mixing region, light guide region or light emission region. In one embodiment, light propagating in the thin film based light guide is redirected by the light redirecting features, the inner light guiding edge or the optical element, such that a full angular width at half maximum intensity of light from the light source incident on the one or more light extraction features is greater in the second plane than in the first plane.

Light emitting apparatus

In one embodiment, a light emitting apparatus includes: a film-based light guide of light guide material having a light guide refractive index nDL, comprising a body having a first surface and an opposing second surface; a plurality of coupling lightguides extending from the body, each of the plurality of coupling lightguides having an end, the plurality of coupling lightguides folded and stacked such that the ends of the plurality of coupling lightguides define a light input surface; the body of the film comprises: a first cladding layer comprising a first material having a first refractive index nD1, a second cladding layer comprising a second material having a second refractive index nD2, wherein nDL > nD2> nD1; a plurality of low angle guiding features optically coupled to a body of the light guide; a plurality of light turning features optically coupled to the lightguide, wherein light propagating at the first angle within the lightguide under total internal reflection is redirected by the low angle directing features to a second angle less than a critical angle for an interface between the core light guiding layer and the second layer, a portion of the redirected light propagating through the interface and being redirected by the light turning features to an angle within 30 degrees of a thickness direction of the film.

In this embodiment, light propagating within the core layer or region of the film-based light guide in the light emission region that experiences low angle light redirection, for example, through the low angle directing features, will preferentially leak or exit the core layer or region of the light guide from the side having the second index of refraction because it is higher than the first index of refraction and higher than the critical angle. In this embodiment, light that is deflected from angles above the critical angle to a smaller angle from the normal to the film surface (or core interface) will first pass through the critical angle boundary on one side of the core or region that is optically coupled to a cladding layer or region having a higher refractive index than the refractive index of the core region or cladding layer or region on the opposite side of the core.

In one embodiment, the low angle directing features are configured to direct light at less than a maximum first total divergence angle θ _f Deviates from the incident angle, following the equation: theta _f ＝θ _c2 -θ _c1 Wherein theta _c2 Is the critical angle between the core layer or region and the second cladding layer or region, which may also be expressed as θ _c2 ＝sin ^-1 (n _D2 /n _DL )，θ _c1 Is the critical angle between the core layer or region and the first cladding layer or region, and may be expressed as θ _c1 ＝sin ^-1 (n _D1 /n _DL ).. In another embodiment, a low angle guide The features are configured to provide a maximum total deviation angle θ _max ，θ _max Less than 110% or theta of the maximum first total divergence angle _max <1.1xθ _f . In another embodiment, the low angle guide features are configured to provide an average first total divergence angle θ _fave At an angle of incidence of theta _fave ＝θ _c2 -θ _c1 . In another embodiment, the low angle guide features are configured to provide an average total deviation angle θ of less than 110% of the average first total deviation angle _ave Or θ _ave <1.1xθ _fave 。

For example, in one embodiment, the first material has a refractive index of nD1=1.4, the second material has a refractive index of nD 2= 1.5, and the core or region material has a refractive index of nDL = 1.6. In this example, the low angle light guiding features include an angled reflective surface, where the angle of the surface results in a small total light differential of θ f, thereby causing light to preferentially exit the core layer of the light guide through the higher index cladding layer or region. In this example, θ c1=61 degrees, θ c2=70 degrees, and thus the maximum first total deviation angle for optimal coupling to the second cladding region is less than 9 degrees. Since the total divergence angle of light reflected from the angled surface is twice the angle of the feature, the angle of the feature with respect to a direction perpendicular to the thickness direction of the film at the feature is selected to be less than 4.5 degrees

In one embodiment, the average angle from a direction perpendicular to the thickness direction of the film at a feature of the surface of a reflective low angle guide feature that receives light propagating within the light guide is less than

Degree or less than 1.1 times

And (4) degree. In another embodiment, the core layer or region of the film-based light guide has a thickness of less than 100 microns and the low angle guiding features are oriented in a single interaction (e.g., single reflection or single refraction)Less than one selected from the group of 100%,80%,60%,40%,30%,20%,10% and 5% of the incident light is directed (e.g., such as by reflection or refraction). In another embodiment, light propagating within the light guide that interacts with the low angle light directing features and propagates to the light turning features interacts with low angle directing features that are, on average, greater than 1, 2, 3, 4, 5, 10, 15, or 20 before reaching the light turning function.

In one embodiment, the ratio of the length of the light emitting region in the direction of light propagating from the first side to the second side of the light emitting region to the average thickness of the light emitting region is greater than a value selected from the group consisting of: 300. 500, 1000, 5,000, 7,000, 10,000, 15,000 and 20,000.

Backlight or frontlight

In one embodiment, the film-based light guide illuminates the display, forming an electroluminescent display. In one embodiment, the film-based light guide is a front light for a reflective or transflective display. In another embodiment, the thin film based light guide is a backlight for a transmissive or transflective display. Typically, for displays comprising a light-emitting light guide for illumination, the position of the light guide will determine whether it is to be considered as backlight or frontlight for an electroluminescent display, where traditionally frontlight light guides are those arranged on the viewing side of the display (or light modulator) and backlight light guides are those arranged on the other side of the display (or light modulator) opposite to the viewing side. However, depending on the definition of the display or display component, the terms frontlight or backlight used in the industry may differ, particularly where the illumination comes from components internal to the display or spatial light modulator (such as where the light guide is disposed between a liquid crystal cell and a color filter or between a liquid crystal material and a polarizer in a liquid crystal display). In some embodiments, the lightguide is thin enough to be arranged within a spatial light modulator, such as between light modulating pixels and reflective elements in a reflective display. In this embodiment, light may be directed to the light modulating pixels directly or indirectly by directing the light to the reflective elements such that the light is reflected towards the spatial light modulating pixels and passes through the light guide. In one embodiment, the light guide emits light from one or both sides and has one or two light distribution profiles, which facilitate "front" and/or "back" illumination of the light modulating component. In embodiments disclosed herein in which the light-emitting area of the lightguide is disposed between the spatial light modulator (or the electro-optic area of a pixel, sub-pixel or pixel element) and the reflective component of the reflective display, light from the light-emitting area may propagate directly towards the spatial light modulator or indirectly by directing the light towards the reflective element such that the reflected light returns through the lightguide and into the spatial light modulator. In this particular case, the terms "front light" and "backlight" as used herein may be used interchangeably.

In one embodiment, a backlight or frontlight for a light emitting display includes a light source, a light input coupler, and a light guide. In one embodiment, the front light or backlight illuminates a display or spatial light modulator selected from the group consisting of: transmissive displays, reflective displays, liquid crystal displays (LCD's), MEM-based displays, electrophoretic displays, cholesteric displays, time-division multiplexed optical shutter displays, color sequential displays, interferometric modulator displays, bistable displays, electronic paper displays, LED displays, TFT displays, OLED displays, carbon nanotube displays, nanocrystal displays, head-mounted displays, head-up displays, segmented displays, passive matrix displays, active matrix displays, twisted nematic displays, in-plane switching displays, advanced fringe field switching displays, vertically aligned displays, blue phase mode displays, zenith bistable devices, reflective LCDs, transmissive LCDs, electrostatic displays, electrowetting displays, TN displays, microcup EPD displays, grating aligned zenith displays, photonic crystal displays, galvanic displays and electrochromic displays.

LCD backlight or frontlight

In one embodiment, a backlight or frontlight suitable for use with a liquid crystal display panel includes at least a light source, a light input coupler, and a light guide. In one embodiment, the backlight or frontlight comprises a single light guide, wherein the illumination of the liquid crystal panel is white. In another embodiment, the backlight or frontlight comprises a plurality of light guides arranged to receive light from at least two light sources having two different color spectra such that they emit light of two different colors. In another embodiment, the backlight or frontlight comprises a single light guide arranged to receive light from at least two light sources having two different color spectra such that they emit light of two different colors. In another embodiment, the backlight or frontlight comprises a single light guide arranged to receive light from red, green and blue light sources. In one embodiment, the light guide comprises a plurality of light input couplers, wherein the light input couplers emit light into the light guide with different wavelength spectra or colors. In another embodiment, light sources emitting light of two different colors or wavelength spectra are arranged to couple light into a single light input coupler. In this embodiment, more than one light input coupler may be used, and the color may be directly controlled by modulating the light source.

In another embodiment, the backlight or frontlight comprises a light guide arranged to receive light from a blue or ultraviolet light emitting source and further comprises an area comprising a wavelength converting material, e.g. a phosphor film. In another embodiment, the backlight includes three layers of thin film light guides, wherein each light guide illuminates the display with substantially uniform luminance when the corresponding light source is turned on. In this embodiment, the color gamut may be increased by reducing the requirements of the color filters, and the display may be operated in a color sequential mode or a full color simultaneous on mode. In another embodiment, the backlight or frontlight comprises a three-layer thin-film light guide having three spatially distinct light-emitting regions that include light extraction features, where each light extraction region for a particular light guide corresponds to a set of color pixels in the display. In this embodiment, by aligning the light extraction features (or areas) to corresponding red, green and blue pixels (for example) in the display panel, then a color filter is not necessary and the display is more efficient. However, in this embodiment, color filters may be used to reduce crosstalk.

In another embodiment, a light emitting device comprises a plurality of light guides (e.g., red, green and blue light guides) arranged to receive light from a plurality of light sources that emit light having different wavelength spectra (and thus different colors) and emit light from substantially different regions corresponding to different color sub-pixels of a spatial light modulator (e.g., an LCD panel), and a plurality of light redirecting elements arranged to redirect light from the light guides to the spatial light modulator. For example, each lightguide may include a cladding region between the lightguide and the spatial light modulator where light redirecting elements such as microlenses are disposed between the lightguide and the light extraction features on the spatial light modulator and direct light toward the spatial light modulator with a FWHM less than 60 degrees, the spatial light modulator with a FWHM less than 30 degrees, the spatial light modulator with an optical axis that emits light within 30 degrees of a normal to an output surface of the spatial light modulator, or the spatial light modulator with an optical axis that emits light within 10 degrees of a normal to an output surface of the spatial light modulator. In another embodiment, the light redirecting elements are arranged in regions between the plurality of light guides and the spatial light modulator to reduce the FWHM of light emitted from the plurality of light guides. Light redirecting elements disposed in regions on a surface such as a thin film layer may have similar or dissimilar light redirecting features. In one embodiment, the light redirecting element is designed to redirect light from the light extraction features of the plurality of light guides into a FWHM angle or optical axis that is within 10 degrees of each other. For example, a backlight including red, green, and blue based thin lightguides may include a microlens array having different focal lengths substantially near the three depths of the light extraction features on the three lightguides. In one embodiment, a light guide film less than 100 microns thick enables the light redirecting elements to be closer to the light extraction features on the light guide and thus capture more light from the light extraction features. In another embodiment, light redirecting elements, such as microlens arrays, having substantially the same light redirecting features (e.g., the same radius of curvature) may be used with thin light guides having light extraction features of different depths because the distance in the thickness direction between the closest and farthest corresponding light extraction features is small relative to the diameter (or size) of the light redirecting element, pixel, or sub-pixel.

Reflective display

In one embodiment, a method of manufacturing a display includes: forming an array of coupling lightguides from a lightguide region of the film comprising the core region and the cladding region by separating the coupling lightguides from each other such that they remain continuous with the lightguide region of the film and comprise a boundary edge at an end of the coupling lightguides; folding the plurality of coupling lightguides such that the boundary edges are stacked; directing light from the light source to a boundary edge of the stack such that the light from the light source propagates through the coupling lightguide and the lightguide region of the film by total internal reflection within the core region of the film; forming light extraction features on or within the core layer in a light emission region of a light guiding region of the film; disposing a light extraction region on or optically coupling the light extraction region to the cladding region in a light mixing region coupling the lightguide region between the lightguide and the light emitting region; and disposing the light emitting region near the reflective spatial light modulator.

The light guides disclosed herein may be used to illuminate reflective displays. In one embodiment, a reflective display includes a first reflective surface and a film-based light guide including a plurality of coupling light guides. In this embodiment, the reflective display may be a diffusely reflective spatial light modulator or a specularly reflective spatial light modulator. For example, the diffusely reflective spatial light modulator may comprise a reflective display, such as an electrophoretic particle-based reflective display, and the specularly reflective spatial light modulator may comprise a reflective LCD with a specularly reflective back electrode. The components of the reflective spatial light modulator, the light emitting device or the light guide or the coating or layer located therein may comprise light scattering or diffusing surfaces or volume light scattering particles or areas.

In one embodiment, the light emitting device is a front light for a watch comprising a reflective display. In another embodiment, the largest dimension in a plane orthogonal to the thickness direction of the display of the light guide or light emission area is less than one selected from the group of 100, 75, 50, 40, 30 and 25 millimeters.

Modes of light emitting devices

In another embodiment, the light emitting device comprises one or more modes selected from the group of: the normal mode of watching, the mode of watching daytime, the hi-lite mode, the low-light mode, the mode of watching night, night vision or NVIS compatible mode, the dual display mode, monochromatic mode, the grey scale mode, transparent mode, panchromatic mode, the high color gamut mode, the color correction mode, the redundant mode, the touch-sensitive screen mode, the 3D mode, the field sequential color mode, the privacy mode, the video display mode, the photo display mode, the alarm mode, the night-light mode, emergency lighting/sign mode. The daytime viewing mode may include driving a device (e.g., a display or a lighting device) at a high brightness (e.g., greater than 300Cd/m 2), and may include using two or more light guides, two or more light input couplers, or driving additional LEDs on one or more light input couplers to generate increased brightness. The night viewing mode may include driving the device at a low brightness (e.g., less than 50Cd/m 2). The dual display mode may include a backlight (or frontlight) in which the light guide illuminates more than one spatial light modulator or display. For example, in a cell phone with two displays in a flipped configuration, each display may be illuminated by the same thin film light guide that emits light to each display. In the transparent mode, the light guide may be designed to be substantially transparent so that a person can see through the display or the backlight. In another embodiment, a light emitting device comprises at least one light guide for a first mode, and a second backlight for a second mode different from the first mode. For example, a transparent mode backlight light guide on a device may have a lower density of light extraction features, but may still be seen through. For high brightness mode on the same device, the second lightguide may provide higher display luminance relative to the transparent mode. The increased color gamut mode may provide an increased color gamut (e.g., greater than 100% ntsc) by using one or more spectrally narrow color LEDs or light sources. These LEDs used in high gamut mode can provide increased color gamut by illuminating through the same or different light guides or light input couplers. The color correction pattern may compensate for changes in light source color over time (e.g., phosphor variations), LED color differences, or changes due to temperature or environment. The touch screen mode may allow one or more light guides to act as a touch screen based on optically hindered TIR. The redundant backlight mode may include one or more light guides or light sources that may operate in the event of a failure or other need. The 3D mode of the light emitting device may include a display and light redirecting elements, or a display and polarization based, LC shutter based or spectrally selective glasses to achieve stereoscopic display. The mode may, for example, include one or more of a separate film-based backlight light guide or film-based light guide for the 3D mode and a display configured to display images stereoscopically. The privacy mode may for example comprise a switchable region of polymer dispersed liquid crystal disposed below the light redirecting element to increase or decrease the viewing angle by switching to a substantially diffuse mode or a substantially clear mode, respectively. In another embodiment, the light emitting device further comprises a video display mode or a photo display mode, wherein the color gamut is increased in this mode. In another embodiment, the light emitting device comprises an alarm mode, wherein one or more light guides are opened to draw attention to the area or display. For example, a light guide formed around or part of the exterior of the cell phone may be illuminated when the cell phone rings to "light" the cell phone when the cell phone rings. By using a film-based light guide, the light guide film can be formed into a phone housing (e.g., thermoformed), or its film can be insert molded into the interior (translucent or transparent housing) or exterior of the housing. In another embodiment, the light emitting device has an emergency mode, wherein at least one light guide is illuminated to provide notification (e.g., display the illuminated word "EXIT") or illumination (e.g., emergency illumination of a hallway). The illumination in one or more modes may be of different colours to provide greater visibility through smoke (e.g. red).

NVIS compatible mode

Night vision or NVIS modes may include illuminating one or more light guides, two or more light input couplers, or driving additional LEDs on one or more light input couplers to produce the desired luminance and spectral output. In this mode, the LED spectrum for NVIS mode may be compatible with U.S. military specification MIL-STD-3009, for example, in applications requiring NVIS compatible mode, LEDs or other light sources with different colors may be used in combination to achieve the desired color and compatibility in day and night mode. For example, a daytime mode may incorporate white LEDs and blue LEDs, while a nighttime or NVIS mode may incorporate white, red, and blue LEDs, where the relative output of one or more LEDs may be controlled. These white or colored LEDs may be arranged on the same light input-coupler or on different light input-couplers, on the same light guide or on different light guides, on the same side of the light guide, or on different sides of the light guide. Thus, each light guide may comprise a single color or a mixture of colors, and a feedback mechanism (e.g. a photodiode or LED used in reverse mode) may be used to control the relative output or compensate for changes in color over time or background (ambient) lighting conditions. The light emitting device may further comprise an NVIS compatible filter to minimize undesired light output, such as a white film based backlight light guide with a multi-layer dielectric NVIS compatible filter, wherein the white light guide is illuminated by white LEDs or white LEDs and red LEDs. In another embodiment, the backlight includes one or more light guides that are illuminated by light from LEDs of one or more of the following colors: red, green, blue, warm white, cold white, yellow and amber. In another embodiment, the backlight further comprises an NVIS compatible filter disposed between the backlight or light guide and the liquid crystal display.

Field sequential color mode

In another embodiment, the backlight or front light comprises: the light redirecting element includes a light guide including light extraction features, and a light redirecting element arranged to receive a portion of light extracted from the light guide and direct the portion of light into a predetermined angular range. In another embodiment, the light redirecting element substantially collimates a portion of the light from the light guide, reduces the full width at half maximum intensity to 60 degrees, reduces the full width at half maximum intensity to 30 degrees, reduces the full width at half maximum intensity to 20 degrees, or reduces the full width at half maximum intensity to 10 degrees, and reduces the percentage of crosstalk light from one light extraction region to reach an undesired adjacent pixel, subpixel, or color filter. When controlling the relative positions of the light extraction features, the light redirecting elements, and the pixels, sub-pixels, or color filters, light from the predetermined light extraction features can be controlled such that little light leaks into adjacent pixels, sub-pixels, or color filters. This is useful in a backlight or frontlight, such as a color sequential backlight, where three light guides (for each of red, green and blue) extract light in a pattern such that no color filters are required (or included to improve color quality, contrast or gamut), since the light is substantially collimated and light extracted from the light guides by light extraction features on the red light guides below the pixel corresponding to the red pixel is not directed to an adjacent blue pixel or only a small portion of the light is directed to an adjacent blue pixel. In one embodiment, the light emitting device is a reflective display comprising a front light comprising three light guides, each light guide having a set of light extraction areas, wherein the three light extraction areas are substantially non-overlapping when viewed at magnification from a viewing side of the display and the light extraction areas are substantially aligned with respective light modulating pixels on the light emitting display. In this embodiment, no color filter is required, whereby the efficiency of the light guide and the light emitting device can be improved. In one embodiment, each lightguide includes a plurality of light extraction regions including substantially one light extraction feature substantially aligned over a light modulating pixel in a reflective spatial light modulator. In another embodiment, each lightguide includes a plurality of light extraction regions, each light extraction region including a plurality of light extraction features, wherein each light extraction region is substantially aligned over a light modulating pixel in the reflective spatial light modulator. In one embodiment, a light emitting display includes a reflective or transmissive spatial light modulator and a thin film based light guide comprising, for each spatial light modulating pixel, when viewed from a normal to a light emitting surface of the display, from: 1. 2, 5, 10, 20, 50, greater than 1, greater than 2, greater than 5, greater than 10, greater than 20, and greater than 50.

In another embodiment, the light emitting device is a reflective display comprising a reflective spatial light modulator and a front or back light comprising three light guides, each light guide comprising a set of light extraction areas, wherein the uniformity of light emitted from the first, second and third light guides when illuminated individually is greater than the uniformity of light emitted from: 60%,70%,80% and 90%. In this embodiment, the intensity of the light source directing light into each light guide may be modulated to provide sequential color illumination for the reflective spatial light modulator.

Single or multiple colour modes

In an embodiment, the light emitting device comprises a first light guide and a second light guide arranged to receive light from a first light source and a second light source, respectively, under light guiding conditions, wherein the color difference Δ u 'v' is greater than a first light source from the second light source of more than 0.004. In another embodiment, the light emitting device comprises three light guides arranged to receive light from three light sources under light guiding conditions, wherein the color difference Δ u 'v' of each of the three light sources is larger than 0.004. For example, in one embodiment, a reflective display includes a front light comprising first, second and third light guides arranged to receive light from red, green and blue LEDs, and each light guide emits light toward a reflective spatial light modulator where it is spatially modulated and the spatial luminance uniformity of the light emission pattern of each light guide is greater than a value selected from the group consisting of: 60%,70%,80% and 90% of the groups.

Multicolour or panchromatic display

In one embodiment, the light emitting device comprises at least one monochromatic light source (e.g., red light emitting diodes) and a white light source (e.g., white light emitting diodes). In another embodiment, a light emitting device includes a light emitting region having a first color light emitting region that emits light from a first light source and a second color light emitting region that emits light from a second light source. In one embodiment, the first color light emitting area is spatially separated from the second color light emitting area. For example, in one embodiment, the light emitting device is a display that includes a monochrome (first color) display area for icons or buttons within or near the display area and a full color display area for viewing full color content. In another embodiment, the first colored light emissive area overlaps at least a portion of the second colored light emissive area. For example, in one embodiment, the light emitting device is a display including a first color light emitting area for icons or buttons within or near the display area and a second color light emitting display area for viewing full color content. In this embodiment, the first color light emitting region may be illuminated by monochromatic light (e.g., in a low power mode) or full color light (e.g., in a higher color gamut mode). In another embodiment, the first colored light emissive area overlaps the second colored light emissive area. For example, in one embodiment, a light emitting device includes a display having a light emitting area including a white illumination light guide configured to receive light from at least one white LED, wherein the white illumination light guide is above or below a full color illumination light guide arranged to receive light from at least one red, green, and blue LED. In this embodiment, the display may be operated in a high brightness, low color saturation mode by turning one or more white LEDs to illuminate, or may be operated in a high color saturation, reduced brightness mode. In one embodiment, two or more light sources having different colors (e.g., white, red, green and blue) are placed to illuminate the same light input surface of the stack of coupling light guides, such that the light emitted from the light emission area may be in a first color mode (e.g., white only) or in a multi-color mode (e.g., red, green and blue modes). For example, in this embodiment, the display may be illuminated from a single film-based light guide, and may be driven using a single color mode, using a full color, high saturation mode of light from red, green, and blue LEDs, or using a lower saturation, full color, higher brightness mode of red, green, blue, and white LEDs.

In one embodiment, the display includes a color filter. In one embodiment, a display including a color filter has a first color gamut when illuminated by a white light source (e.g., a white-emitting LED including a Yttrium Aluminum Garnet (YAG) phosphor having a correlated color temperature between 3700K and 4000K) and a second color gamut different from the first color gamut when illuminated by one or more monochromatic light sources (e.g., red, green and blue LEDs). In one embodiment, the first color gamut is selected from: less than 60%, less than 70%, less than 80%, less than 90%, less than 100%, greater than 60%, greater than 70%, greater than 80%, greater than 90%, and greater than 100% of a National Television Systems Committee (NTSC) color gamut, the second color gamut being selected from the group consisting of: less than 70%, less than 80%, less than 90%, less than 100%, greater than 70%, greater than 80%, greater than 90%, greater than 100%, greater than 110%, and greater than 120% of the group of National Television Systems Committee (NTSC) color gamuts.

In one embodiment, the light emitting device directly or indirectly monitors the intensity or color of one or more light sources. In another embodiment, the light emitting device monitors the intensity or color of the light emitting area. The intensity or color can be monitored in real time using a photodetector, such as a photodiode, photocell or light emitting diode used in reverse mode, to detect light within a particular wavelength range. In an embodiment, the light emitting device monitors color and/or intensity to adjust for degradation of ambient light conditions or components. For example, in one embodiment, the light emitting device includes a light emitting diode positioned to receive light from the plurality of light sources and as the light output decreases over time, the current increases such that the light output remains substantially the same. In another embodiment, the relative light output of two light sources, such as red and blue LEDs, is monitored so that the relative light output can be maintained and the color remains substantially the same. In this embodiment, the light emitting device may comprise a plurality of light guides illuminated by a plurality of monochromatic light sources such that the light emitting device is in a color sequential mode. In another embodiment, the light emitting device monitors the light after it has passed through the light guide area. In one embodiment, a light emitting device includes a first light input coupler positioned to receive light from a first light source and a second light input coupler positioned to receive light from a second light source. In this embodiment, the light passing through the light guide region is monitored by measuring the relative intensity of light passing through the first array of coupling light guides in the first light input coupler, the light guide region, and the second array of coupling light guides in the second light input coupler comprising the second array of at least one LED driven in a reverse mode to detect the intensity of light exiting the coupling light guides at the light input surface. In this embodiment, degradation of one or more components of the light guide or light guide optical system may be monitored for degradation, such as yellowing due to ultraviolet exposure, and the relative output of the light source may be increased (e.g., increasing the light output from the blue LED to preserve color). In one embodiment, one or more light sources in the first input-coupler are turned on and light sources in the second input-coupler are turned off so that a photodiode or light emitting diode in the second optical input-coupler can measure light from one or more light sources in the first input-coupler that passes through the input-coupler and the light guide. This may be performed in a test mode, before or during the display being turned on, or in a viewing mode. In one embodiment, the light transmissive material of the core and/or cladding regions of the thin film based light guide has an absorption coefficient α (absorption) that is greater than a value selected from the group consisting of: 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8 per inch. In one embodiment, the light transmissive material of the core and/or cladding regions of the thin film based light guide has an attenuation coefficient α (attenuation), resulting in absorption and scattering, greater than that selected from the group consisting of: 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8 per inch. Attenuation or absorption coefficients can be measured by sequentially measuring the light output from a length of light guide material, using a "reduction" method similar to that used to estimate the attenuation of an optical fiber, including cutting the material and then fitting the data to a curve model.

In one embodiment, the intensity of light from a first monochromatic first light source is increased to adjust absorption and/or attenuation losses within the light transmissive material over a range of wavelengths. For example, in one embodiment, a light emitting device includes at least one red, green, and blue LED light source, the light transmissive material of the core layer of the light guide absorbs more blue light than red light, and the light intensity from the blue light emitting diode is at least a first intensity adjustment percentage greater than the intensity required to meet at least 70%,80%, or 90% of the NTSC color gamut at a particular luminance (e.g., 50, 100, 200, or 300 candelas per square meter)) if the light is not absorbed or attenuated by the light transmissive material in the film-based light guide. This comparison may be made by directly measuring (without passing through the light guide) the color gamut of the light of the red, green, and blue LEDs and the light exiting the light-emitting region of the film-based light guide. For example, in one embodiment, to meet the 80% NTSC gamut at 300 candelas/m 2 in the light emission area of the display, the first intensity adjustment percentage of the increase in intensity of the light from the blue LEDs is 20% of the intensity required to reach the 80% NTSC gamut, since the film-based light guide is not used but is directly illuminated by the LEDs. In one embodiment, the first intensity adjustment percentage is greater than a value selected from: 5%, 10%,20%,30%,40%,50%,60%,70%,80%,90% and 100%.

In one embodiment, the color filter array includes one or more color filters of colors selected from the group consisting of: red, green, blue, cyan, magenta, yellow, orange and violet. In one embodiment, the light emitting device is a color display comprising at least one color filter having a first wavelength transmission bandwidth with a transmittance at normal incidence of greater than 60% and at least one light source having a peak wavelength output within the first wavelength transmission bandwidth. In another embodiment, the light emitting device is a display comprising a color filter array including a first color filter, a second color filter, and a third color filter having first, second, and third wavelength bandwidths, respectively. In this embodiment, the display further comprises first, second and third light sources emitting light within the first, second and third wavelength bandwidths, respectively, or emitting light having peak intensities within the first, second and third wavelength bandwidths.

In one embodiment, the light emitting device comprises one or more monochromatic light sources, and the light extraction features are diffractive in nature. For example, in one embodiment, the light extraction features are diffractive elements positioned to directly (by transmission) or indirectly (by reflection) diffract incident light out of the light guide such that the light exits the light guide on a side of the light guide opposite the diffractive elements). In an embodiment, the diffractive element comprises a linear blazed grating. In one embodiment, a light emitting device includes a lightguide having a first diffractive element light extraction feature and a second diffractive element light extraction feature different from the first diffractive element light extraction feature, a first light source emitting light having a first peak wavelength, a second light source emitting light having a second peak wavelength different from the first peak wavelength, wherein the first diffractive element light extraction feature diffracts light from the first light source out of the lightguide (directly or indirectly from an opposite side) without diffracting incident light emitted from the second light source out of the lightguide (directly or indirectly). In another embodiment, the second diffractive element light extraction features diffract light from the second light source out of the light guide (directly or indirectly from the opposite side) without diffracting incident light from the first light source out of the light guide (directly or indirectly). In another embodiment, the full width at half maximum intensity within the light guide of light incident on the diffractive element light extraction features within the light guide is less than one selected from the group of 100, 90, 80, 70, 60, 50, 40, 30, 20, and 10 degrees in one or more illumination planes.

Automatic or user-controlled color adjustment

In one embodiment, the light emitting device may operate in a monochrome mode (such as a blue-only mode). In another embodiment, a user of the light emitting device may selectively select the color of light emitted from the display or the light emitting device. In another embodiment, the user may choose to change the mode and relative light output intensity from one or more light sources. For example, in one embodiment, the user may switch from a full color 2D display using only front light to a stereoscopic 3D display mode. In one embodiment, a user can adjust the color temperature of the white point of a display by adjusting the light output of red LEDs relative to white LEDs, the display comprising a film-based light guide and a light input coupler arranged to couple light from the red LEDs and the white LEDs into a coupling light guide of the light guide. In another embodiment, a user may switch the reflective display from a fixed white point color temperature front light only mode to an automatic white color temperature adjusting front light and ambient light mode that automatically adjusts the light output of the red LEDs relative to the white LEDs (or the relative intensities of the blue, green, and red LEDs, etc.) to maintain the color temperature of the display white point under various ambient spectral conditions, such as fluorescent "cold" light and incandescent "warm" light. In another embodiment, the user may select to change from a full color RGB display mode to an NVIS compatible display mode with less red output. In another embodiment, the user may select a monochrome mode that changes from RGB illumination of the light of the red, green, and blue LEDs to light of the white LED.

In another embodiment, a film-based light guide is configured to receive light from a substantially white light source and a red light source. For example, by coupling light from white and red LEDs, the color temperature of the display can be adjusted. This may be altered by the user (e.g., for color preference) or automatically, for example. For example, in one embodiment, a light emitting device includes a reflective display and a photosensor (e.g., one or more photodiodes with oppositely operating color filters or LEDs) that detects the color or spectral intensity of light within one or more wavelength bandwidths and adjusts the overall and/or relative light output intensity of the front light (or LEDs that couple light into a single front light) to increase or decrease the luminance and/or adjust the combined color of light emitted from the reflective display. In another embodiment, the light detector (or photosensor) used to detect the color or spectral intensity of light within one or more wavelength bandwidths also determines the relative brightness of the ambient light, and the intensity of light from the front light is increased or decreased based on a predetermined or user-adjusted setting. In one embodiment, the photosensor includes one or more photosensors, such as LEDs used in a reverse mode. In one embodiment, the photosensors are disposed in one or more locations selected from the group consisting of: the display is behind the display, behind the front light, between the light emitting area of the display and the bezel, bezel or frame of the display, within the frame of the display, behind the housing or housing of the display or light emitting device or the housing or light transmissive window of the housing, and in an area of the light emitting device separate from the display area. In another embodiment, the photosensor includes red, green, and blue LEDs that are back-driven to detect the relative intensities of the red, green, and blue spectral components of the ambient light. In another embodiment, the photosensor is arranged at an input surface of an arrangement of coupling lightguides arranged to transmit light from the one or more light sources to a light emitting area of the film-based lightguide or to an output surface of an out-coupling lightguide extending from the film-based lightguide. In this embodiment, the photosensor can effectively collect the average intensity of light incident on the display and the film-based light guide front light and can compare it to the relative output of light from the light source in the device. In this embodiment, due to the large area of the light collection sensor, which is due to the large spatial area comprising the light extraction features, which effectively operate as in-coupling features in the reverse mode, coupling a part of the ambient light into the light guide under waveguide conditions towards the photosensor of the photosensor.

One or more modes of the light emitting device may be configured to automatically turn on in response to an event. The event may be user-oriented, such as turning on a high-gamut mode when the handset is used in a video mode, or in response to an environmental condition, such as a thin-film based emergency light electrically coupled to a smoke detection system (internal or external to the device) turning on when smoke is detected, or automatically turning on a high-brightness display mode when a high ambient light level is detected.

In another embodiment, the display mode may be changed from a lower luminance, higher color gamut mode (e.g., a mode using red, green, and blue LEDs for display illumination) to a higher luminance, lower color gamut mode (e.g., using white LED illumination). In another embodiment, the display may be switched (automatically or by user control) from a higher color gamut mode (e.g., a light emitting device emitting light from red, green, and blue LEDs) to a lower color gamut mode (e.g., using white phosphor LEDs). In another embodiment, the display is switched automatically or by user control from a high electrical power mode (e.g., a light emitting device emitting light from red, green and blue LEDs) to a relatively low electrical power mode (e.g., a mode using only substantially white LEDs) to obtain equal display luminance.

In yet another embodiment, the display is switched, either automatically or by user control, from a color sequential or field sequential color mode front-light or back-lighting mode to an ambient lighting mode in which the light output from the front-light is turned off or substantially reduced and the ambient light accounts for more than 50% of the flux leaving the display screen.

In one embodiment, a display includes a film-based light guide having a light input-coupler arranged to receive light from one or more light sources emitting light having a color selected from one or more of the group consisting of: red, green, blue, cyan, magenta, and yellow. For example, in one embodiment, a display includes a film-based light guide that includes one or more light input couplers positioned to receive light from red, green, blue, cyan, and yellow LEDs. In this embodiment, the color gamut of the display may be significantly increased compared to a display comprising only red, green and blue illumination LEDs. In one embodiment, the LEDs are arranged in one optical input coupler. In another embodiment, two or more LEDs of two different colors are provided to input light into the arrangement of coupling lightguides. In another embodiment, the first light input-coupler comprises one or more LEDs having a first spectral output profile of light entering the thin-film based light guide; and a second light input-coupler, light having a second spectral output profile different from the first spectral output profile being incident into the film-based light guide, and the coupling light guides in the first light input-coupler and the first or second light input-coupler are arranged to receive light from LEDs having a first peak wavelength and an output wavelength bandwidth of less than 100nm on the input surface, while the coupling light guides in the other light input-couplers are not arranged to receive light from LEDs having a substantially similar peak wavelength and a substantially similar output wavelength bandwidth at the input surface. In another embodiment, a light emitting device includes two or more light input couplers including different configurations of different color LEDs. In another embodiment, a light emitting device includes two or more light input couplers comprising substantially identical configurations of different color LEDs.

Stereoscopic or multi-picture display mode

In another embodiment, a display capable of operating in a stereoscopic display mode includes a backlight or frontlight, wherein at least one light guide or light extraction region is disposed within or above a film-based light guide, wherein at least two sets of light emission regions can be individually controlled to produce at least two sets of images in conjunction with the stereoscopic display. The 3D display may further include a light redirecting element, a parallax barrier, a cylindrical lens element, or other optical components to effectively convert the spatially separated light regions into angularly separated light regions before or after spatially modulating the light.

In another embodiment, a light emitting device comprises at least one first light guide emitting light in a first angular range and at least one second light guide emitting light in a second angular range. By employing a light guide emitting light in two different angular ranges, viewing angle dependent properties may be created, such as a dual view display or a stereoscopic display or a backlight. In one embodiment, the optical axis of the first light guide emission is at substantially +45 degrees to the normal of the light output surface, while the optical axis of the second light guide emission is at substantially-45 degrees to the normal of the light output surface. For example, a display used in a car display dashboard between a driver and a passenger may display different information to each person, or the display may more efficiently direct light to two viewers rather than wasting light by directing it perpendicular to the surface.

In another embodiment, the light emitting device comprises two or more backlights, wherein each backlight emits light having an off-axis light output profile with one or two peaks corresponding to the eyes of the viewer, such that the display is viewable in a stereoscopic mode. In another embodiment, light from two or more backlights is emitted in two different directions in at least one output plane (e.g. 0 degrees and 30 degrees in the horizontal viewing plane, or +30 degrees and-30 degrees in the horizontal viewing plane), respectively, so that two viewers of the same display may see two different videos with high contrast (lower percentage of ghosting, where one image penetrates into the viewing area of the other viewer, similar to the term used in stereoscopic displays) when the images on the display are synchronized with the backlight output. In this example, the left-side viewer's image (e.g., viewing a first movie) is displayed at 120Hz (using a display with a refresh rate of at least 240 Hz) and is illuminated by a first backlight with a peak luminous intensity of-30 degrees, the right-side viewer's image (e.g., viewing a television program) is displayed at a frequency of 120Hz and is illuminated by a second backlight with a peak luminous intensity of +30 degrees, wherein the left-and right-viewer's images are alternately displayed across the display and the light output from the first and second backlights is turned on and off accordingly. In this embodiment, the full pixel count (pixel format) of the display may be used for both viewers. In another embodiment, three or more backlights are used, for example backlights with peak angular luminous intensities at-30 degrees, 0 degrees and +30 degrees, which are extended to three or more viewing zones. Similarly, in another embodiment, the display may include four viewing zones (e.g., -30, -10, +10, and + 30), where four different videos may be displayed for four different viewers (e.g., each video displayed at a 60Hz refresh rate for a display having a refresh rate of 240 Hz), and/or a backlight having a higher luminance may be selected by a viewer sitting or standing at a particular location (thus, for example, there is greater flexibility where a viewer may sit and watch television). In another embodiment, a display including two or more backlights includes two or more audio channel decoders and two or more corresponding wireless transmitters (such as bluetooth or infrared) to transmit different audio channels to two or more viewers using headphones.

In another embodiment, the first light guide emits light corresponding to light of the display illuminating a first area (or a first time period of the display) corresponding to the left image, and the second light guide emits light corresponding to light of the display illuminating a second area corresponding to the right image (or a second time period of the display) such that the display is a stereoscopic 3D display.

In one embodiment, a first lightguide emits substantially white light in a direction from a first set of light extraction features at a first angle, and a second lightguide below the first lightguide emits substantially white light in a direction from a second set of light extraction features at a second angle. In another embodiment, the first set of light extraction features is arranged below a first set of pixels corresponding to a left display image, and the second set of light extraction features is substantially spatially separated from the first set and arranged below a second set of pixels corresponding to a right display image, and the display is autostereoscopic. In another embodiment, the autostereoscopic display further comprises a third light guide that emits light towards the first and second sets of pixels and is illuminated at full resolution in the 2D display mode.

In one embodiment, a light emitting display includes a thin film based light guide and a reflective spatial light modulator, wherein light reflected by the reflective spatial light modulator is from light incident from the light guide due to light extracted from the light guide traveling in a first direction that is substantially non-overlapping with light reflected at the reflective spatial light modulator from light incident from the light guide that is extracted from light traveling in a second direction different from the first direction. In one embodiment, a light emitting display includes a reflective spatial light modulator having diffuse reflective properties, wherein a full width at half maximum intensity of the diffusely reflected light is less than an angle selected from the group consisting of: one of the group of 50 degrees, 40 degrees, 30 degrees, 20 degrees and 10 degrees. In one embodiment, a diffusely reflective spatial light modulator receives light propagating within a film-based light guide from two peak directions, exiting the light guide, with the optical axis oriented substantially in opposite directions. For example, in this embodiment, light propagating in a first direction within the light guide may be extracted from the light guide such that it is incident on the reflective spatial light modulator at a peak luminous intensity angle of +20 degrees from the normal of the reflective spatial light modulator having a full width at half maximum intensity at the first output plane at 10 degrees, and light propagating in a second direction opposite to the first direction within the light guide may be extracted from the light guide such that it is incident on the reflective spatial light modulator at a peak luminous intensity angle of-20 degrees from the normal of the reflective spatial light modulator having a full width at half maximum intensity at 10 degrees at the first output plane. In this embodiment, light originally propagating in the light guide in the first direction is output at an angle of peak luminous intensity of about-20 degrees from the display normal, and light originally propagating in the light guide in the second direction is output from the display at an angle of about +20 degrees from the display normal in the first output plane. By modulating the light output (e.g., alternating the light from two white light LEDs coupled to two in-coupling light guides on opposite sides of the light emission area) and synchronizing it with the reflective spatial light modulator, the alternating images from the display can be directed to +20 and-20 degrees directions for the viewer to see a stereoscopic 3D image, indicia, graphics, or video. In another embodiment, the angle of peak intensity of light from the first and second directions varies across the front light such that the light is focused towards two "eyeboxes" corresponding to a range of viewing positions of an ordinary viewer's eyes at a particular viewing distance. In one embodiment, the peak luminous intensity at the center of the display is at an angle to light initially propagating with its optical axis in the first direction of the thin-film based light guide within a range selected from the group consisting of: -40 to-30 degrees, -30 to-20 degrees, -20 to-10 degrees and-10 to-5 degrees from the normal to the display surface in the first output plane; and the peak luminous intensity at the center of the display is at an angle to light originally propagating with its optical axis in a second direction of the film-based light guide within a range selected from: from the normal to the display surface in the first output plane, +40 degrees to +30 degrees, +30 degrees to +20 degrees, +20 degrees to +10 degrees, and 10 degrees to +5 degrees. In another embodiment, the first output plane is substantially parallel to the first direction and the second direction.

In one embodiment, a light emitting display includes cylindrical lenses arranged to direct light into two or more viewing areas to display images, videos, information, or indicia stereoscopically, and is or includes a film-based light guide. In this embodiment, the thickness of the stereoscopic display may be reduced by incorporating a film-based light guide into the lenticular lens film. In a further embodiment, stray light reflections from front light at the air-micro-cylinder surface are reduced by directing light from the cylinder lens towards the reflective display without passing through the micro-cylinder-air surface until after reflection from the reflective spatial light modulator.

Privacy mode or variable angle output mode using two or more backlights

In another embodiment, a light emitting device includes a first backlight (e.g., an edge-lit backlight, a direct-lit backlight, or a film-based lightguide backlight) and a second backlight including a film-based lightguide having a light emitting area positioned over the light emitting area of the first backlight on an observation (output) side of the first backlight. In another embodiment, the angular light output from the first backlight is different from the angular light of the second lightguide. In one embodiment, a Full Angular Width (FAWHMLI) at half maximum luminous intensity along one or both light output planes orthogonal to the light emission surface of the first backlight or the second backlight is greater than one selected from the group consisting of: 40. 50, 60, 70, 80, 90, 100, 110 and 115 degrees ("higher FAWHMLI"). In another embodiment, the FAWHMLI along one or both light output planes orthogonal to the light emission surface of the first backlight and the second backlight is less than one selected from the group consisting of: 5. 10, 15, 20, 30, 40, 50, 60, 70 and 80 degrees ("lower FAWHMLI"). In these embodiments, "lower FAWHMLI" and "higher FAWHMLI" are relative to their FAWHMLI of each other. For example, one backlight may have a privacy mode with a lower FAWHMLI less than 15 degrees and a wider viewing mode with a higher FAWHMLI greater than 60 degrees. Also, in another embodiment, one backlight may have a privacy mode with a lower FAWHMLI of less than 60 degrees and a wider viewing mode with a higher FAWHMLI of 115 degrees. In one embodiment, light output from the light-emitting region second film-based light guide backlight is substantially collimated and suitable for use in privacy mode applications. In another embodiment, the FAWHMLI of light output from the first backlight along one or two light output planes orthogonal to the light emitting surface of the first backlight is less than or more than light output from the second backlight in the same output plane is selected from one of the following groups: 5. 10, 15, 20, 30, 40, 50, 60, 70, 80 and 90 degrees. For example, in one embodiment, the first backlight is an edge-lit backlight using an acrylic sheet waveguide and optionally one or more diffusing or brightness enhancing films, and has a FAWHMLI greater than 60 degrees in the horizontal light output plane (optionally, and/or in the vertical output plane), and the light emission area of the second backlight (e.g., a thin film based light guide backlight comprising one or more light input couplers and one or more LEDs) is located above the light emission area of the first backlight, wherein the angular output of the second backlight is less than 60 degrees in the horizontal direction (optionally and/or in the vertical direction). In this embodiment, when the first backlight is lit, the viewing angle of the display located above the first and second backlights has a wide horizontal viewing angle (higher level FAWHMLI) when only the first backlight is lit (and optionally both the first backlight and the second backlight are lit); when the second backlight is lit, the display has a lower horizontal viewing angle (privacy mode, lower horizontal FAWHMLI) when only the second backlight is lit. In another embodiment, adding a light-emitting region of a second backlight (e.g., a film-based lightguide) over a light-emitting region of a first backlight, when only the first backlight is emitting light, causes the FAWHMLI light output of the device along one or both light output planes orthogonal to the light-emitting surface to change by less than one selected from the group of 2, 5, 10, 15, 20, and 30 degrees. In one embodiment, the film-based light guide of the second backlight has a light-emitting area that does not substantially redirect or alter light output from the first backlight when placed over (or in the path of) the light-emitting area of the first backlight on the light-emitting side of the first backlight. For example, the second film-based light guide backlight may include a layer or region having light-turning features, wherein the light-turning features occupy less than 40%,30%,20%, or 10% of the surface area of the light-emitting region. In embodiments where the light redirecting elements (and optionally the light extraction features) occupy a low percentage of the surface area of the light emission area, light from the first backlight may propagate through the second backlight substantially without deviation. In another embodiment, when only the first backlight emits light and the light emission region of the second backlight is located above the light emission region of the first backlight, the percentage of the total luminous flux emitted from the light emission device including the first backlight and the second backlight is greater than, selected from one of the following groups: 75%, 80%,85%,90%,92%,92%,94%,96% and 98% of the total luminous flux leaving only the first backlight when only the first backlight is lit and the second backlight is not located above the first backlight. In another embodiment, a second film-based light guide backlight includes light extraction features that occupy less than 40%,30%,20%, 10%,5% of the surface area of the light emission region. In one embodiment, the second film-based light guide is backlit between a light guide sheet or diffuser (backlight for direct illumination) and one or more diffuser films and/or brightness enhancement films (e.g., linear prism films). In one embodiment, due to the use of low angle guiding features in the light guide and light turning features in another layer or region, a lower FAWHMLI for the second backlight is achieved in a first output plane (e.g., a horizontal output plane or a vertical output plane); due to the collimation (or reduction of FAWHMLI) in the input plane of light from one or the light sources at the light input surface perpendicular to the thickness direction of the film (and/or the stacked coupling lightguides) before entering the light input plane (e.g., by using light collimating optics that collimate the light in at least one plane of incidence), a lower FAWHMLI for the second backlight is optionally achieved in a second output plane orthogonal to the first output plane, or alternatively achieved by collimating (or reducing FAWHMLI) within the coupling lightguide or light mixing region (e.g., by shaping or tapering the coupling lightguide or internal light guiding edges). In another embodiment, a light emitting device includes two or more backlights having different FAWHMLI light outputs in one or more light output planes, and the relative light outputs from the two or more backlights can be adjusted to achieve a FAWHMLI profile between providing the respective FAWHMLI of the two or more backlights in the one or more light output planes. For example, in one embodiment, in a horizontal viewing plane, a first backlight has a light output with a FAWHMLI of 115 degrees, a second backlight positioned above the first backlight has a light output with a FAWHMLI of 40 degrees, and when the first backlight is driven at 40% luminous flux output and the second backlight is driven at 90% luminous flux output, the combination of the first backlight (and optionally the display) has a FAWHMLI of 60 degrees. In another embodiment, the angular light output profile of the one or more backlights does not have an angular luminous intensity peak at 0 degrees. For example, in one embodiment, the first backlight may have a FAWHMLI of 40 degrees centered at 0 degrees with respect to the normal to the light emission surface (in the horizontal and/or vertical light output plane), and the second backlight may have two luminous intensity peaks centered at +50 and-50 degrees. In this embodiment, for example, a first backlight may be used in the front low viewing angle mode, and when the viewer wishes to extend the viewing mode, a second backlight may be turned on to 100% power (or less than 100%,90%, 80%,70%,60%,50% and 40%, for example) to increase the viewing angle accordingly.

Privacy mode or variable angle output mode using two or more light sources

In one embodiment, a light emitting device includes a plurality of light sources positioned to emit light into a first light input surface defined by one or more stacks of a plurality of coupling lightguides, wherein light from one or more first light sources in a light input coupler for a thin-film based lightguide has a lower FAWHMLI before entering at least the first light input surface in an input plane orthogonal to a thickness direction of the coupling lightguide and light from one or more second light sources has a higher FAWHMLI before entering at least the first light input surface in the input plane orthogonal to the thickness direction of the coupling lightguide. In this embodiment, for example, a light collimating optical element (e.g., a total internal reflection lens or a metallized collimating lens or mirror) is positioned to receive light from the one or more first light sources and output light of a lower FAWHMLI that is less than one of the group of 5, 10, 15, 20, 30, 40, 50, 60, 70 degrees, and 80 degrees in at least a light input plane at a light input surface perpendicular to a thickness direction of a coupling lightguide of the thin-film based lightguide. In this embodiment, the one or more second light sources emit light such that a FAWHMLI in at least a light input plane at a light input surface orthogonal to a thickness direction of a coupling lightguide of the film-based lightguide is greater than one selected from the group consisting of: 40. 50, 60, 70, 80, 90, 100, 110 and 115 degrees. Thus, by selectively turning on only the first light source due to the light collimating optical element, the light output from the light emitting area of the light emitting device (and optionally the display) has a lower FAWHMLI in the light output plane from the light emitting area parallel to the array direction of the array of coupling lightguides; and when only the second light source is switched on, the light output from the light emitting area of the light emitting device has a higher FAWHMLI from the light output plane of the light emitting area parallel to the array direction of the array of coupling light guides. In this embodiment, light corresponding to a lower FAWHMLI (narrow viewing angle or privacy mode) is emitted in one plane by the first light source, and by turning off the first light source and turning on the second light source, light from the second light source is emitted from the light emission area in an output plane parallel to the array direction in a wider FAWHMLI (wide viewing angle or non-privacy mode). In another embodiment, the light emitting device comprises two or more light sources having different corresponding FAWHMLI light outputs in one or more light output planes, and the relative light output from the two or more light sources can be adjusted to achieve a FAWHMLI profile between the respective FAWHMLIs of the two or more light sources in the one or more light output planes. For example, in one embodiment, in a horizontal viewing plane, the light output from the backlight has a FAWHMLI of 115 degrees when illuminated by only the first light source, and the backlight has a FAWHMLI of 40 degrees when illuminated by only the second light source, and the light output of the backlight (and optionally the display) has a FAWHMLI of 60 degrees when the first light source is driven at 40% luminous flux output and the second light source is driven at 90% luminous flux output.

In the case of a backlight or display illuminated by the first light source, the FAWHMLI of light output in a light output plane parallel to the array direction of the array of coupling lightguides may be less than one selected from the group of: 5. 10, 15, 20, 30, 40, 50, 60, 70 and 80 degrees. In the case of a first and second light source illuminated backlight or display, the FAWHMLI of light output in a light output plane parallel to the array direction of the array of coupling lightguides may be greater than one selected from the group of 40, 50, 60, 70, 80, 90, 100, 110 and 115 degrees. In one embodiment, the light collimating element may be positioned to receive and collimate (or reduce FAWHMLI) light output from two or more light sources. In another embodiment, one or more light sources having respective light collimating elements are placed near and/or between two or more light sources that do not have respective light collimating elements positioned to receive a light output. In one embodiment, the one or more light sources corresponding to the lower FAWHMLI light output from the light emitting device and the one or more light sources corresponding to the higher FAWHMLI light output from the light emitting device are both located on the same circuit board or flexible printed circuit.

Other apparatus

In one embodiment, the film-based light guide illuminates a display, a phase modulation device, a component of an optical communication device, a component of a medical device, or a component of an analytical device. In another embodiment, an apparatus includes a film-based light guide, and one or more light sources emit light having a constant phase wavefront, light having a uniform phase wavefront, light having a predetermined phase wavefront, light having a compensated phase wavefront, or light having a phase-adjustable wavefront, over an entire area or one or more sub-regions of a light input surface area of a light input coupler for the film-based light guide. In one or more embodiments, light exiting the light emitting region of the light emitting device is reflected from or transmitted through the spatial modulation device (phase and/or amplitude) and may or may not pass through one or more regions of the light guide (e.g., the light emitting region). If light from the modulation device returns through the light guide, the modulation element may pre-compensate for phase or amplitude variations due to passage through the light guide to produce a predetermined phase or amplitude output (e.g., a uniform constant phase wavefront).

Spatially varying display

In one embodiment, a display device includes a thin film based light guide in which light output from a light emitting region provides illumination to an amplitude or phase spatial light modulator. In this embodiment, the light output from the light emitting region of the light guide may have one or more selected from the group of: a constant phase wavefront, a uniform phase wavefront, a predetermined phase wavefront, a random phase wavefront, a compensated phase wavefront, or a phase modifiable wavefront over the entire area or spatially varying over the entire light emitting area. For example, in one embodiment, the light emitting region emits light that is directed onto a Liquid Crystal On Silicon (LCOS) phase modulation device. The LCOS device may spatially modulate the phase of light reflected from the modulation device to create a diffraction pattern that forms a near-field or far-field spatial image, a phase wavefront, or an amplitude wavefront. By illuminating a spatial light modulator (phase or amplitude modulator) with light from light sources having different peak luminous intensity wavelengths (e.g., red, green and blue LEDs or red, green and blue lasers), the transmitted light or reflected light from the spatial light modulator can form a far field image, video or phase wavefront. In this embodiment, light from light sources having different peak intensities may be directed through the same input-coupler, different input-couplers on the same film, or input-couplers on multiple film-based light guides. Light sources emitting light having wavelengths outside the visible spectrum (e.g., infrared or ultraviolet wavelengths) may be used to provide displays for specific applications, such as night vision compatible displays or wavelength conversion displays that include one or more fluorophores, phosphors, quantum dots, up-conversion materials or other materials that convert light of a first spectral range of wavelengths to a second spectral range different from the first spectral range of wavelengths.

By spatially modulating the phase of the light from the LCOS device, the phase (or amplitude) change received from the output of the light emitting region of the light guide can be compensated and further modulated to produce a spatially varying phase (or amplitude) wavefront. In one embodiment, the display is a head-mounted display, a head-up display (e.g., for use in a vehicle or aircraft), a projection display, a pico projector, a near-eye display, a wedge projection display, a digital holographic display, a direct view display, a virtual display, an integrated display based on a microlens array, or a light field display. In one embodiment, the spatial light modulator is positioned to spatially modulate (amplitude or phase) light prior to entering the light input surface of the light input coupler of the light emitting device, wherein the modulated light propagates through the light mixing region to the light emitting region and is emitted from the light emitting region in the form of a two-dimensional array of light emission locations. In this embodiment, the light from the light emitting region may form a direct view display, a virtual display or a light field display. Light may be guided from the light emitting region of the light guide using one or more selected from the group consisting of: light extraction features, light redirecting features, low angle orientation features, light turning features, high index regions or layers, low index regions or layers, and light redirecting optical elements.

In another embodiment, a spatial light modulator is positioned to spatially modulate (amplitude or phase) light received from a light-emitting region of a thin film based light guide, where the modulated light can be transmitted through the spatial light modulator (transmissive spatial light modulator) or reflected from the spatial light modulator (reflective spatial light modulator). For a reflective spatial light modulator, the thin film based light guide may be positioned such that light that is spatially modulated and reflected by the spatial light modulator returns through the thin film based light guide (e.g., returns through the light emitting area of the thin film based light guide).

Head Mounted Display (HMD)

In one embodiment, a Head Mounted Display (HMD) includes a thin film based light guide in which light output from a light emitting region illuminates an amplitude or phase spatial light modulator. In one embodiment, light from the light emitting region is used as front light or backlight to provide illumination to the amplitude or phase spatial light modulator. In another embodiment, spatially modulated light from an amplitude or phase spatial light modulator is directed onto an input surface of a light input coupler, propagates through a light guide film, is emitted from a light guide, and is directed to one or more eyes of a viewer wearing a head-mounted display. In one embodiment, the eyewear frame or one or more arms of the frame comprise one or more selected from the group consisting of: light mixing regions of the light guide, inactive regions of the light guide, spatial light modulators, light sources, and electronics. In one embodiment, the light-emitting region of the film-based light guide is positioned on the surface of the eyewear or within the lens. In another embodiment, the head mounted display is an accessory that may be permanently or removably attached to eyewear such as sunglasses or prescription eyeglasses. In this embodiment, the light-emitting region may be a film that may be pressed, laminated, glued, placed adjacent, physically coupled or optically coupled to or placed near the eyewear or eyewear frame. In one embodiment, the array of coupling lightguides extends along a side of the eyewear in a range selected from 5%,10%,15%,15%,20%,30%,40%,50%,60%, and 70% of the length of the eyewear platform. In another embodiment, the light-mixing region of the light guide extends along a side of the eyewear in a range selected from 5%,10%,15%,20%,30%,40%,50%,60%, and 70% of the length of the eyewear platform.

Head-up display (HUD)

In one embodiment, a head-up display (HUD) system includes a film-based light guide in which light output from a light-emitting region provides illumination to an amplitude or phase spatial light modulator. In one embodiment, the light emitting region of the film-based light guide is positioned on a surface or window or light transmissive substrate. A head-up display including a film-based light guide may be configured to be substantially transparent when not displaying information or images, and/or substantially transparent in a non-light-emitting region based on an image being displayed. In another embodiment, the HUD is an accessory that may be permanently or removably attached to a window or mirror of an automobile, vehicle, or aircraft. In this embodiment, the light-emitting region may be a film that may be extruded, laminated, glued, adjacent, physically coupled or optically coupled to or adjacent to a window, substrate, lens or light transmissive material.

Multiple light-emitting areas or displays

In one embodiment, the light emitting device comprises two or more light emitting areas or displays defined by regions having one or more properties selected from the group consisting of: emitting a different color gamut; emitting light in different functional areas of the display; emitting light having different angular characteristics; illuminating to illuminate a button, key, keypad area or other user interface area; have different sizes or shapes; and on different sides or surfaces of the device. In one embodiment, the light emitting device comprises two or more light emitting areas with different usage patterns or different illumination patterns. The different illumination modes may comprise one or more different light output properties selected from the group of: the illumination times of the "on" state or the "off state are different; different illumination frequencies; different illumination durations; illumination of different colors; a different color gamut; different angular light output profiles; different spatial light output profiles; different spatial luminance uniformity; have different colors, luminances or luminous intensities under specific angles. For example, in one embodiment, the light emitting device illuminates the main display and the sub-display. The main display and the sub-display may be two light emitting areas defined by the same spatial light modulator or two light emitting areas defined by two independent spatial light modulators. In one embodiment, each light emitting region or display may be illuminated by the same or different light guides and/or light sources. For example, in one embodiment, a light emitting device has a high-gamut light guide positioned to front illuminate a main display of a device having a main display and a secondary display with light from monochromatic red, green, and blue LEDs in a first mode. In this embodiment, the secondary display may be illuminated by a second light guide that emits only white light to reduce the power required to illuminate the secondary display (which may, for example, include icons or keys) to the same brightness. In another embodiment, the first display area includes an array of color filters and the second display area does not include an array of color filters. For example, in one embodiment, the secondary display may be designed without an array of color filters, so that a monochromatic secondary display illuminated by a white (or monochromatic) light source may operate at significantly lower power, yet achieve the same illumination as the primary light source with the array of color filters, since the light is not absorbed by the array of color filters.

In one embodiment, the device comprises two or more light guides spatially separated in the plane of the active area of the light emitting device such that they can be illuminated independently. In this embodiment, for example, the edge of one or more light guides opposite the side of the light guide with the light input-coupler may comprise a light-reflecting or absorbing coating to prevent light from leaving this light guide and entering an adjacent light guide. In an embodiment, the spatially separated light guides allow the light emitting display device to have a substantially uniform thickness.

Light emitting device assembly

In one embodiment, the film-based light guide is adhered to a display, a component of a display, or other component of a light emitting device using lamination and/or one or more of the following: pressure increase, heat increase, laminating coated layers or areas, laminating to the relative position retaining element, and applying adhesive to the substrate or component and joining one component to another.

In one embodiment, the adhesive acts as a cladding layer between the core region of the lightguide and another component and reduces the light flux absorbed by the RPME due to the lightguide contacting the RPME. In another embodiment, the pressure sensitive adhesive increases the yield strength or impact strength (e.g., izod or charpy impact strength) of the film-based light guide, light emitting device, and/or display. In one embodiment, an adhesive is placed between the light guide and the reflective film, the surface of the opposing position-retaining element, or the optical component arranged to receive light from the light source and direct it into the input surface of the coupling light guide stack.

Luminance uniformity of backlight, frontlight or light emitting devices

In another embodiment, the light sources emitting light into the array of coupling lightguides comprise two or more differently colored light sources (e.g. red, green and blue LEDs), and the spatial color unevenness Δ u 'v' measured on a 1976 u ', v' uniform chromaticity scale described in VESA flat panel display measurement standard version 2.0, 6/1/2001, (appendix 201, page 249) is less than one selected from the group of 0.2, 0.1, 0.05, 0.01 and 0.004 along a line parallel to the array of coupling lightguides or perpendicular to the optical axis of light traveling along the length of the coupling lightguides on a side of the tapered surfaces within the coupling lightguides proximal to the coupling light sources. In an embodiment, the color difference Δ u 'v' of the two light sources arranged to emit light into the light input surface is larger than 0.1, and the spatial color unevenness Δ u 'v' of the light from the two light sources in the coupling light guide is smaller than 0.1 before entering the tapered region.

By cutting the coupling light guide in a direction orthogonal to the optical axis of light propagating within the coupling light guide and placing a spectrometer (or input to a spectrometer, such as a fiber optic collector) along the cut edge in a direction oriented along the optical axis of light exiting the coupling light guide, the spatial color non-uniformity of light traversing the coupling light guide at a particular location along the coupling light guide can be measured.

In one embodiment, a light emitting device comprises a light source, a light input coupler, and a thin film based light guide, wherein a 9-spot spatial luminance uniformity of a light emitting surface of the light emitting device measured according to VESA panel display metrics version 2.0 (6/1/2001) is greater than a luminance uniformity value selected from the group consisting of: 60%,70%,80%,90% and 95%. In another embodiment, a display comprises a spatial light modulator and a light emitting device comprising a light source, a light input coupler and a thin film based light guide, wherein a 9-spot spatial luminance uniformity (measured by placing a white reflective standard surface, such as Spectralon manufactured by Labsphere, inc., at a position where the spatial light modulator would receive light from the light guide and measuring light reflected from the standard surface on 9 spots according to VESA Flat Panel display Standard version 2.0, 6/1/2001) is greater than one selected from the group consisting of 60%,70%,80%,90% and 95%. In another embodiment, a display comprises a spatial light modulator and a light emitting device comprising a light source, a light input coupler and a thin film based light guide, wherein the 9-spot spatial luminance uniformity of the display measured according to VESA flat panel display measurement Standard version 2.0 (6.1/6/2001) is greater than one selected from the group consisting of 60%,70%,80%,90% and 95%.

Color uniformity of backlight, frontlight or light emitting devices

In one embodiment, a light emitting device comprises a light source, a light input coupler, and a thin film based light guide, wherein 9 spot sample spatial color non-uniformities Δ u 'v' of the light emitting surface of the light emitting device measured on a 1976 u ', v' uniform chromaticity scale described in VESA flat panel display measurement standard version 2.0, 6/1/2001, (appendix 201, page 249) are less than one selected from the group of 0.2,0.1,0.05,0.01, and 0.004 when measured using a spectrometer based spot colorimeter. In another embodiment, a display comprises a spatial light modulator and a light emitting device comprising a light source, a light input coupler and a thin film based light guide, wherein a 9-spot sampled spatial color non-uniformity Δ u 'v' of light reaching the spatial light modulator (measured by placing a white reflective standard surface, such as Spectralon, at the location of the spatial light modulator to receive light from the light guide and according to the vasa flat panel display measurement standard version 2.0, year 2001, 6, month 1, (appendix 201, page 249) the 1976 u ', v' uniform chromaticity scale described) is less than a value selected from the group consisting of: 0.2,0.1,0.05,0.01 and 0.004. In another embodiment, a display comprises a spatial light modulator and a light emitting device comprising a light source, a light input coupler and a thin film based light guide, wherein the 9-point sampled spatial color non-uniformity Δ u 'v' of the display is measured according to the 1976 u ', v' uniform chromaticity scale described in VESA Flat Panel display measurement Standard version 2.0, 6.1.2001, (appendix 201, page 249) is less than one selected from the group of 0.2,0.1,0.05,0.01 and 0.004 when measured using a spectrometer based spot colorimeter.

Angular profile of light emitted by a light emitting device

In one embodiment, the light emitted from at least one surface of the light emitting device has an angular half maximum intensity full angular width (FWHM) less than one selected from the group consisting of: 120 degrees, 100 degrees, 80 degrees, 60 degrees, 40 degrees, 20 degrees, and 10 degrees. In another embodiment, the light emitted from at least one surface of the light emitting device has at least one angular peak of intensity within at least one angular range selected from: from the normal of the light emitting surface 0-10 degrees, 20-30 degrees, 30-40 degrees 40-50 degrees, 60-70 degrees, 70-80 degrees, 80-90 degrees, 40-60 degrees, 30-60 degrees and 0-80 degrees. In another embodiment, the light emitted from at least one surface of the light emitting device has two peaks in one or more of the above angular ranges, and the light output is similar to a "batwing" type profile known in the lighting industry to provide uniform illumination over a predetermined angular range. In another embodiment, the light emitting device emits light from two opposing surfaces within one or more of the above-mentioned angular ranges, and the light emitting device is one selected from the group consisting of: a backlight that illuminates two displays on both sides of the backlight, a lamp that provides upper and lower light, illuminates a front light of the display, and outputs light on a viewing side of the front light, the light not being reflected from a modulating component of the reflective spatial light modulator, and a peak angle of luminance being greater than 40 degrees, 50 degrees, or 60 degrees. In another embodiment, the optical axis of the light emitting device is within an angular range selected from the group consisting of: from 0-20, 20-40, 40-60, 60-80, 80-100, 100-120, 120-140, 140-160, 160-180, 35-145, 45-135, 55-125, 65-115, 75-105 and 85-95 degrees from the normal of the light emitting surface. In another embodiment, the light guide is substantially tubular in shape and light propagates through the tube substantially in a direction parallel to the longer (length) dimension of the tube and exits the tube, wherein at least 70% of the light output flux is contained within an angular range of 35 degrees to 145 degrees from the light emission surface. In another embodiment, the light emitting device emits light from a first surface and a second surface opposite to the first surface, wherein the light fluxes respectively emitted from the first surface and the second surface are selected from: 5-15% and 85-95%,15-25% and 75-85%,25-35% and 65-75%,35-45% and 65-75%, 45-55% and 45-55%. In another embodiment, the first light emission surface emits light substantially in a downward direction and the second light emission surface emits light substantially in an upward direction. In another embodiment, the first light emitting surface emits light substantially in an upward direction and the second light emitting surface emits light substantially in a downward direction.

Method for manufacturing optical input/output coupler

In one embodiment, the light guide film and the light input or light coupler are formed from a light transmissive film by forming segments in the film that correspond to the coupling light guides and translating and bending the segments so that the segments overlap. In another embodiment, the input surfaces of the coupling lightguides are arranged to produce a collective light input surface by translation of the coupling lightguides to produce at least one bend or fold.

Film production

In one embodiment, the film or light guide is one selected from the group consisting of: extruded films, coextruded films, cast films, solvent cast films, UV cast films, pressed films, injection molded films, scratch coated films, spin coated films, and coated films. In one embodiment, one or two cladding layers are coextruded on one or both sides of the light guiding region. In another embodiment, a tie layer, adhesion promoting layer, material or surface modification is provided on or between the cladding layer and the surface of the light guiding layer. In one embodiment, the coupling lightguides or core regions thereof formed during the film formation process are continuous with the lightguide region of the film. For example, a coupling lightguide formed by slicing regions of a film at spaced intervals may form a coupling lightguide that is continuous with the lightguide region of the film. In another embodiment, a film-based light guide having coupling light guides continuous with a light guide region may be formed by injection molding or casting a material in a mold comprising the light guide region with the coupling light guide region, the mold comprising the light guide region with the coupling light guide region with a space between the coupling light guides. In one embodiment, the region between the coupling light guide and the light guide region is homogenous and free of interfacial transitions such as, but not limited to, air gaps, small changes in refractive index, discontinuities in shape or input-output area, and small changes in molecular weight or material composition.

In another embodiment, at least one selected from the group of: a light guide layer, light transmissive film, cladding regions, adhesive regions, adhesion promoting regions, or scratch resistant layer is coated on one or more surfaces of the film or light guide. In another embodiment, the light guide or cladding region is coated, extruded, or otherwise disposed on a carrier film. In one embodiment, the carrier film allows at least one selected from the group consisting of: ease of handling, fewer static issues, ability to use conventional paper or packaging folding equipment, surface protection (scratches, dust, creases, etc.), helping to obtain a flat edge of the light guide during cutting, ultraviolet absorption, shipping protection, and use of winding and film equipment with a wider range of tension and flatness or alignment adjustments. In one embodiment, the carrier film is removed before the film is applied, before the coupling lightguide is bent, after the coupling lightguide is folded, before the light extraction features are added, after the light extraction features are added, before printing, after printing, before or after the conversion process (further lamination, bonding, die cutting, punching, packaging, etc.), before being ready for installation, after installation (when the carrier film is the outer surface), and during the removal of the lightguide from installation. In one embodiment, one or more additional layers are laminated to the core region (or layers coupled to the core region) in segments or regions such that the presence of the film is absent from the area of the one or more additional layers. For example, in one embodiment, an optical adhesive used as a cladding layer is optically coupled to a touch screen substrate; and optically coupling the touch screen substrate to a light emitting area of the thin film based light guide using an optical adhesive, thereby leaving the coupling light guide free of cladding layers to improve input coupling efficiency.

In another embodiment, the carrier film is cut or removed over the area where the light guide is coupled. In this embodiment, the coupling light guide may be bent or folded to a smaller radius of curvature after the carrier film is removed from the linear fold region.

Relative position holding member

In one embodiment, the at least one relative position maintaining element substantially maintains the relative position of the coupling lightguides in the region of the first linear fold region, the second linear fold region, or both the first and second linear fold regions. In one embodiment, the relative position maintaining element is disposed adjacent to the first linear fold region of the array of coupling lightguides such that the combination of the relative position maintaining element and the coupling lightguides provides sufficient stability or stiffness to substantially maintain the relative position of the lightguide element within the first linear fold region during translational movement of the first linear fold region relative to the second linear fold region that produces the overlapping set of bends in the coupling lightguide and the coupling lightguide. The relative position maintaining elements may be adhered, clamped, arranged in contact, arranged against the linear fold region or arranged between the linear fold region and the light guide region. The relative position maintaining element may be a polymer or metal component adhered or maintained on the surface of the coupling light guide, light mixing region, light guide region or film at least during one of the translatory steps. In one embodiment, the relative position maintaining element is a polymeric strip having flat or serrated teeth attached to either side of the film adjacent the first linear fold region, the second linear fold region, or both the first and second linear fold regions of the light guide. By using serrated teeth, the teeth may facilitate or facilitate bending by providing an angled guide. In another embodiment, the relative position holding element is a mechanical device having a first clamp and a second clamp that hold the coupling light guide in a relative position in a direction parallel to the clamps parallel to the first linear fold region and translate the positions of the clamps relative to each other such that the first linear fold region and the second linear fold region translate relative to each other to create the overlapping coupling light guide and bend in the coupling light guide. In another embodiment, a relative position maintaining element maintains the relative position of the coupling light guide in the first linear fold region, the second linear fold region, or both the first linear fold region and the second linear fold region and provides a mechanism to apply a force onto the end of the coupling light guide to translate the coupling light guide in at least one direction.

In another embodiment, the relative position maintaining element comprises angled teeth or regions that redistribute the force when the at least one coupling light guide is bent or maintain a uniform distribution of the force after the at least one coupling light guide is bent or folded. In another embodiment, the relative position maintaining elements redistribute the forces from bending and pulling the one or more coupling lightguides from the corners to the length of the substantially angled lightguide. In another embodiment, the angled guide edges are rounded.

In another embodiment, the relative position maintaining elements redistribute the forces from bending during the bending operation and provide a resistance to maintain the force required to maintain a low profile (short dimension in the thickness direction) of the coupling light guide. In one embodiment, the relative position maintaining element comprises a low contact area region, material or surface relief region that acts as a low contact area cover or region, wherein one or more surface relief features are in physical contact with the region of the light guide during the light guide folding operation and/or during use of the light emitting device. In one embodiment, low contact area surface relief features on the relative position maintaining elements reduce decoupling of light from the coupling light guide, the light mixing region, the light guide region, or the light emitting region.

In another embodiment, the relative position maintaining element is also a heat transfer element. In one embodiment, the relative position maintaining element is an aluminum component with angled guides or teeth that is thermally coupled to the LED light source.

In another embodiment, a method of making a light guide and a light input-coupler comprising a light transmissive film having a light guide region that is successively coupled to each coupling light guide in an array of coupling light guides, wherein the array of coupling light guides comprises a first linear fold region and a second linear fold region that is substantially parallel to the first fold region, comprises the steps of: (a) An array of coupling lightguides in a light-transmissive film physically coupled to lightguide regions is formed by physically separating at least two regions of the light-transmissive film in a first direction. (b) Increasing a distance between a first linear fold region and a second linear fold region of the array of coupling lightguides in a direction perpendicular to a surface of the light transmissive film at the first linear fold region; (c) Reducing a distance between a first linear fold region and a second linear fold region of the array of coupling lightguides in a direction substantially perpendicular to the first linear fold region and parallel to a surface of the light-transmissive film at the first linear fold region; (d) Increasing a distance between a first linear fold region and a second linear fold region of the array of coupling lightguides in a direction substantially parallel to the first linear fold region and parallel to a surface of the light-transmissive film at the first linear fold region; and (e) reducing a distance between the first linear fold region and the second linear fold region of the array of coupling lightguides in a direction perpendicular to the surface of the light-transmissive film at the first linear fold region; such that the coupling lightguides are curved, substantially stacked on top of each other, and aligned substantially parallel to each other.

In another embodiment, the aforementioned method further comprises the steps of: the overlapping coupling lightguides are cut through to provide an array of input edges of the coupling lightguides, the array of input edges terminating in a plane substantially orthogonal to the surface of the light-transmissive film. The coupling lightguides can be formed by cutting a film into lines to form slits in the film. In another embodiment, the above method of manufacturing further comprises forming an array of coupling lightguides in the light transmissive film by cutting substantially parallel lines in the light transmissive film. In one embodiment, the slits are substantially parallel and equally spaced. In another embodiment, the slits are not substantially parallel or have a non-constant spacing.

In another embodiment, the aforementioned method further comprises the steps of: holding the overlapping arrays of coupling lightguides in a fixed relative position by at least one selected from the group consisting of: clamping them together, constraining motion by providing walls or housings around one or more surfaces of the overlapping arrays of coupling lightguides, and bonding them together or adhering to one or more surfaces.

In another embodiment, the input ends and the output ends of the array of coupling lightguides are respectively placed in physical contact with the relative position maintaining elements during steps (a), (b), (c) and (d) above.

In one embodiment, a relative position maintaining element disposed proximal to a first linear fold region of an array of coupling lightguides has an input cross-sectional edge in a plane parallel to the light-transmissive film, the input cross-sectional edge being substantially linear and parallel to the first linear fold region; and the relative position maintaining element disposed proximal to the second linear fold region of the array of coupling lightguides at the second linear fold region of the array of coupling lightguides has a cross-sectional edge in a plane parallel to the light transmissive film at the second linear fold region, the light transmissive film being substantially linear and parallel to the linear fold region.

In another embodiment, the cross-sectional edges of the relative position maintaining elements disposed proximal to the first linear fold region of the array of coupling lightguides and the cross-sectional edges of the relative position maintaining elements disposed proximal to the second linear fold region of the array of coupling lightguides remain substantially parallel during steps (a), (b), (c), and (d).

In another embodiment, a method of making a light guide and a light input-coupler comprising a light transmissive film having a light guide region optically and physically coupled to each coupling light guide in an array of coupling light guides, wherein a first fold region and a second fold region are defined in the array of coupling light guides, comprises the steps of: (a) Translating the first fold region and the second fold region away from each other in a direction substantially perpendicular to the surface of the film at the first fold region such that they move toward each other in a plane parallel to the surface of the film at the first fold region, and (b) translating the first fold region and the second fold region away from each other in a direction parallel to the first fold region such that the first fold region and the second fold region move toward each other in a direction substantially perpendicular to the surface of the film at the first fold region, thereby bending and substantially overlaying the coupling lightguides onto each other.

Angled teeth

In another embodiment, the relative position maintaining element disposed proximal to the first linear fold region has a cross-sectional edge in a plane parallel to a surface of the light transmissive film disposed proximal to the first linear fold region, the cross-sectional edge including a substantially linear portion oriented at an angle greater than 10 degrees to the first linear fold region of the at least one coupling light guide. In another embodiment, the relative position maintaining elements have serrated teeth that are oriented at substantially 45 degrees with respect to the linear fold region of the coupling light guide. In one embodiment, the cross-sectional edges of the opposing position-maintaining elements form guiding edges to guide the bending of the at least one coupling light guide. In another embodiment, the relative position maintaining element is thicker than the coupling light guide folded around or near the relative position maintaining element, such that the relative position maintaining element (or regions such as teeth or angled extension regions) does not cut or provide a narrow region for local stresses that may cut, crack or induce stress on the coupling light guide. In another embodiment, the ratio of the thickness of the relative position-maintaining elements or features (e.g., angled teeth) to the average thickness of the coupling light guide that is contacted during or after folding is greater than one selected from the group consisting of: 1. 1.5, 2, 3, 4, 5, 10, 15, 20 and 25. In one embodiment, the relative position maintaining element (or a component thereof) in contact with the coupling lightguide during or after folding is greater than one selected from the group consisting of: 0.05, 0.1, 0.2, 0.3, 0.5, 0.6, 0.7, 0.8, 0.9 and 1 mm.

In one embodiment, the array of angled teeth in the RPME includes a first tooth edge oriented at a first tooth edge angle to the direction of extension of the teeth (direction of extension of the teeth from the ridge, perpendicular to the array direction of the teeth) and a second tooth edge oriented at a second tooth edge angle to the direction of extension of the teeth, wherein the first tooth edge angle and the second tooth edge angle are each greater than 0 degrees. In one embodiment, the light input coupler comprises an RPME, wherein the direction of extension of the teeth is parallel to the direction of extension of the array of coupling lightguides and the direction of the array of teeth is parallel to the direction of the array of coupling lightguides. In one embodiment, the first edge tooth angle is in a range selected from the group consisting of: 40 to 50 degrees; 35 degrees and 55 degrees; 30 degrees and 60 degrees; 25 degrees and 65 degrees; 20 degrees and 65 degrees; 15 degrees and 70 degrees. In another embodiment, the second edge tooth angle is in a range selected from one of the following groups: 0 degree, greater than 5 degrees, greater than 10 degrees, greater than 20 degrees, greater than 25 degrees, greater than 0 degrees and less than or equal to 5 degrees, greater than 0 degrees and less than or equal to 10 degrees, greater than 0 degrees and less than or equal to 15 degrees; greater than 0 degrees and less than or equal to 20 degrees, and between 1 and 20 degrees.

In one embodiment, the light input-coupler includes a folded and stacked array of first and second coupling lightguides extending from the film body, and a radius of curvature of the first coupling lightguide at the first fold is less than a radius of curvature of the second coupling lightguide at the second fold. In this embodiment, the RPME includes first and second teeth positioned within the folds of the first and second coupling lightguides, respectively, and an average thickness of the first teeth at the first fold is less than an average thickness of the second teeth at the second fold. The tooth thickness direction is a direction perpendicular to a plane including a direction in which the teeth extend from the ridge and an arrangement direction of the tooth array. In this embodiment, the larger radius of curvature of the second coupling light guide allows the second tooth to be thicker and the second coupling light guide to have a larger contact area at the first edge of the second tooth. The larger contact area may distribute the force from the tension over a larger area during or after the folding operation and reduce the likelihood of the coupling light guide tearing or creasing. In another embodiment, the RPME includes a first tooth and a second tooth, and a first average thickness of a first edge of the first tooth is less than an average thickness of a first edge of the second tooth. In this embodiment, the angled edges may be thicker than other regions of the teeth to reduce the weight and/or volume of the RPME.

In one embodiment, the angled teeth of the RPME include two linear edges having a curved region with a first radius of curvature between the two linear edges. In one embodiment, the first radius of curvature is greater than one selected from the group consisting of: 0.1, 0.5, 1, 2, 4, 8, 10, 20, 30, 40, 50, 100, 200, and 500 millimeters. In this embodiment, the curved region is less likely to cut or tear the coupling light guide during folding, application to the light guide, or alignment operations than a sharp intersection of the edges.

In one embodiment, the angled teeth of the RPME are truncated at the base (the region where the teeth connect to the ridge of the RPME). For example, in one embodiment, the angled teeth comprise two intersecting linear edges (or curved regions with a radius of curvature between them), and on opposite ends of these edges comprise truncated linear regions that may be substantially parallel to the direction of extension of the array of coupling light guides.

In one embodiment, one or more angled teeth in the RPME are truncated at the junction of the angled teeth and the ridge or between the first edge and the second edge. In one embodiment, the length of the first edge of the angled tooth is less than the width of the corresponding coupling light guide folded around the tooth, and the angled tooth is truncated to allow flexibility in the self-alignment of the coupling light guides along the first edge during the folding and/or stacking steps. In another embodiment, the angled teeth are truncated and the ratio of the length of the first edge to the width of the coupling light guide folded around the edge for one or more teeth and coupling light guide is one selected from: less than 1, less than 0.9, less than 0.8, less than 0.7, less than 0.6, less than 0.5, greater than 1, greater than 1.1, greater than 1.2, greater than 1.3, greater than 1.4, greater than 1.5, between 0.1 and 2 and more than 2. In this embodiment, the reduced first edge length and/or the truncated teeth reduce the likelihood of uneven stress or tension on the coupling light guide, reduce the likelihood of creasing or tearing the coupling light guide, increase the positional tolerance of the coupling light guide before or after folding, or increase the folding or rotational tolerance of the coupling light guide. In another embodiment, the ridge of the RPME comprises one or more protrusions, guides or standoffs positioned to contact the lateral edges of the plurality of folded and stacked coupling lightguides to limit their position in the first direction of extension. In one embodiment, a protrusion, guide or abutment on the RPME aligns the light guide in the direction of extension while reducing the length (and area) of the lateral edge of the coupling light guide that contacts the RPME ridge. In one embodiment, the ridge comprises one or more protrusions, guides or standoffs that contact one or more lateral edges of the stacked array of coupling light guides at a first contact percentage of a total area of the lateral edges of the one or more lateral edges of the stacked array of coupling light guides in a region from the folded end to the light input surface. In one embodiment, the first contact percentage is selected from: less than 100 percent, less than 90 percent, less than 80 percent, less than 70 percent, less than 60 percent, less than 50 percent, less than 40 percent, less than 30 percent, less than 20 percent, less than 10 percent, less than 5 percent, less than 2 percent, and less than 1 percent. In one embodiment, the reduced contact area reduces light extraction and/or light absorption of light reaching the lateral edges from the interior of the coupling lightguide.

Ridge of RPME

In one embodiment, the RPME includes a ridge configured to support an array of aligned, leading or angled teeth. In another embodiment, the ridge of the RPME is connected to an array of angled teeth, wherein the ridge does not extend beyond the angled teeth portion of the RPME. In this embodiment, when the array of coupling lightguides is folded 90 degrees and stacked, the lateral edges of the stacked coupling lightguides may be translated from the fold point by a first fold distance in a plane parallel to the light emitting film such that the angled teeth couple together in the upper region of the ridge (the region of the RPME fold side) without extending beyond the angled teeth of the RPME. In this embodiment, the total volume of the RPME may be reduced, thereby reducing the total volume of the input coupler. In one embodiment, the first folding distance is a translation distance Dn. In one embodiment, the width of the ridge region is less than or equal to the translation distance Dn. In another embodiment, the angled teeth or guides of the RPME physically couple within the volume of the fold region of the array of coupling lightguides defined between overlapping portions of the array of coupling lightguides. In another embodiment, the angled teeth or guides of the RPME are physically coupled by a ridge that does not extend beyond the volume defined between the overlapping portions of the array of coupling lightguides in the folded region. In another embodiment, the angled teeth or guides of the RPME are physically coupled by ridges that do not extend beyond the lateral edges of the array of folded and stacked coupling lightguides. In another embodiment, the ridge extends along a side (e.g., a folded side in a folding direction from a light guide region of the film-based light guide) such that the angled teeth or guides intersect the ridge at that side. In another embodiment, the ridges do not extend beyond the angled teeth of the RPME.

In one embodiment, the RPME includes alignment guides, such as holes, ribs, openings, teeth, protrusions, or connectors, on one, two, three, or four sides of the RPME. For example, in one embodiment, the RPME is longer in a first direction than a second orthogonal direction and includes one or more alignment holes near both ends along the longer direction. In one embodiment, the one or more alignment guides are positioned on a side of the RPME opposite the teeth in the second orthogonal direction.

Folding and assembling

In one embodiment, the heat-coupling light guide is heated to soften the light guide during the folding or bending step. In another embodiment, the coupling light guide is folded when its temperature is higher than a temperature selected from one of the following groups: 50 degrees celsius, 70 degrees celsius, 100 degrees celsius, 150 degrees celsius, 200 degrees celsius, and 250 degrees celsius.

Folding device

In one embodiment, the coupling light guide is folded or bent using opposing folding mechanisms. In another embodiment, grooves, guides, pins, or other counterparts facilitate bringing together opposing folding mechanisms so that the folds or bends in the coupling lightguides are folded correctly. In another embodiment, alignment guides, grooves, pins or other counterparts are provided on the folder to hold in place or guide one or more coupling light guides or light guides during the folding step.

Sequence of assembly

In one embodiment, the film-based light guide includes an array of coupling light guides, and the array of coupling light guides is folded prior to physically or optically coupling the film-based light guide to a light emitting device, a display, or a component thereof. In another embodiment, the array of coupling lightguides is folded after physically or optically coupling the film-based lightguide to a light emitting device, display, or component thereof. In another embodiment, a light emitting device or display comprises a light input coupler comprising an array of folded, stacked, coupled light guides, and the light input coupler is assembled before or after laminating the film-based light guide to the display. In one embodiment, the display is used as a relative position holding element, and during a subsequent folding operation, a film-based light guide is adhered to the display to hold the relative position of the coupling light guides.

The following is a more detailed description of various embodiments depicted in the accompanying drawings.

Fig. 1 is a top view of one embodiment of a light emitting device 100 comprising a light input-coupler 101 arranged on one side of a film-based light guide. The light input-coupler 101 comprises a coupling light guide 104 and a light source 102, the light source 102 being arranged to guide light into the coupling light guide 104 through a light input surface 103 comprising an input edge of the coupling light guide 104. In one embodiment, each coupling light guide 104 terminates at a boundary edge. Each coupling light guide is folded such that the boundary edges of the coupling light guides are stacked to form the light input surface 103. The light emitting device 100 further comprises a light guiding region 106, which light guiding region 106 comprises a light mixing region 105, a light guide 107 and a light emitting region 108. Light from the light source 102 exits the light input coupler 101 and enters the light guiding region 106 of the film. As the light propagates through the light guide 107, it is spatially mixed with light from the different coupling light guides 104 in the light mixing region 105. In one embodiment, light is emitted from the light guide 107 in the light emitting region 108 due to light extraction features (not shown).

Fig. 2 is a perspective view of one embodiment of a light input-coupler 200 in which the coupling lightguides 104 are folded in the-y direction. Light from the light source 102 is guided to the light input surface 103 through or along the light input edge 204 of the coupling light guide 104. A portion of the light from the light source 102 propagates within the coupling light guide 104, where a directional component in the + y direction will be reflected in the + x and-x directions from the lateral edges 203 of the coupling light guide 104, and will be reflected in the + z and-z directions from the top and bottom surfaces of the coupling light guide 104. Light propagating within the coupling light guide is redirected by folds 201 in the coupling light guide 104 into the-x direction.

Fig. 3 is a top view of an embodiment of a light emitting device 500, wherein two light input couplers 101 are arranged on the same side of the light guiding area 106. In this embodiment, the light sources 102 are directed light substantially opposite each other in the + y and-y directions.

FIG. 4 is a top view of one embodiment of a light emitting backlight 1000 configured to emit red, green, and blue light. The light emitting backlight 1000 comprises a red light input coupler 1001, a green light input coupler 1002 and a blue light input coupler 1003 arranged to receive light from a red light source 1004, a green light source 1005 and a blue light source 1006, respectively. Light from each of the light in-

couplers

1001, 1002 and 1003 is emitted from the light emitting region 108 due to light extraction features 1007 which redirect a portion of the light to an angle closer to the surface normal within the light guide region 106 so that the light therefore does not remain within the light guide 107 but leaves the light emitting backlight 1000 in the light emitting region 108. The pattern of light extraction features 1007 can have different sizes, spaces, spacings, pitches, shapes, and locations throughout the thickness of the lightguide in the xy-plane or z-direction.

Fig. 5 is a cross-sectional side view of one embodiment of a light emitting device 1100 comprising a light input-coupler 101 and a light guide 107, wherein a reflective optical element 1101 is disposed adjacent to the cladding region 602 and a light source 1102 having an optical axis in the + y direction is disposed to direct light into the coupling light guide 104. Light from the light source 1102 propagates through the coupling lightguide 104 within the light input coupler 101, through the light mixing region 105, and through the core layer 601 of the lightguide 107 within the light emitting region 108 of the lightguide region 106. Referring to fig. 5, a first portion of light 1104 that reaches light extraction features 1007 is redirected toward reflective optical element 1101 at an angle less than the critical angle so that the light can exit light guide 107, reflect from reflective optical element 1101, return through light guide 107, and exit light guide 107 through light emission surface 1103 of light emission region 108. A second portion of light 1105 reaching the light extraction features 1007 is redirected at an angle less than the critical angle toward the light emission surface 1103, out of the light guide 107, and out of the light guide 107 through the light emission surface 1103 of the light emission region 108.

Fig. 6 is a perspective view of an embodiment of a light emitting device 1500 in which the light mixing region 105 of the light guide 107 encloses a relative position holding element 1501 and a stack of a plurality of coupling light guides 104 extending from the light guide 107 and stacked in the y-direction. Relative position maintaining elements 1501 substantially maintain the relative position of coupling lightguides 104 during and/or after folding. The light source 102 is operably coupled to the relative position maintaining element 1501 and directs light into the light input edge 204 of the coupling lightguide 104 such that the light propagates through the coupling lightguide 104, propagates through the light mixing region 105 encased in the coupling lightguide 104, and exits the lightguide 107 in the light emitting region 108. The light source 102 may be operatively coupled to the relative position holding element 1501, for example, by adhesion, clamping, physical restraint, or another suitable physical coupling device or method. Similarly, one or more of

coupling lightguides

104, 107 or regions of lightguides 107, such as light mixing region 105, may be adhered or otherwise operably coupled to relative position-holding element 1501. Operably coupling one or more elements of the light emitting device 1500 can reduce the overall volume of the device, reduce the likelihood of contaminants entering the area between the components, and prevent the one or more elements from being unwrapped or unfolded. In one embodiment, the light guide 107 is adhered to itself in the area of the wrapping material using an adhesive, such as a suitable pressure sensitive adhesive, which may be a cladding layer. In another embodiment, the light emitting device comprises one or more tapered, angled or unfolded coupling light guides, and the light sources 102 are located between the planes defined by the lateral edges 1502 of the light guides 107 (parallel to the x-y plane in fig. 6)) to reduce the size of the device in the z-direction.

FIG. 7 is a top view of one embodiment of coupling lightguides 1610a,1610b, and 1610c in three

different positions

1601, 1602, and 1603, respectively. FIG. 7 shows the translation distance of the folded coupled lightguides 1610b,1610c in the extension direction 1614 from the fold line 1609 when folding is initiated at 90 degrees from the fold point 1608 for two different radii. In this embodiment, the fold line 1609 is a line that includes a fold point 1608 where the coupling light guides (e.g., 1610b,1610 c) begin to fold, and in this embodiment, perpendicular to the direction of extension 1614 of the coupling light guides 1610b,1610c for a 90 degree fold. In this embodiment, reduced widths of the

coupling lightguides

1610a,1610b,1610c are shown for illustrative purposes and clarity. Coupling lightguide 1610a extends from lightguide 107 in extension direction 1614 (parallel to the-x direction) in unfolded position 1601 (shown in dashed lines). The coupling light guide 1610b in the second position 1602 is folded in the + z-direction and the + y-direction to a first radius of curvature to result in a 90 degree fold (coupling light guide axis 1612 is 90 degrees from the extension direction 1614). In the second position 1602 (shown in dashed lines), the coupling light guide 1610b has a first radius of curvature R1. In the third position 1603, the coupling light guide 1610c has a second radius of curvature R2, the second radius of curvature R2 being greater than the first radius of curvature R1. For the second position 1602, a first translation distance D1 in the direction of extension of the midpoint 1606 of the coupling light guide 1610b (in the x-y plane) is:

For the third position 1603, at midpoint 1 of the coupling light guide 1610c604 (in the x-y plane) is:

with a larger radius of curvature R2, the coupling light guide 1610c at the third position 1603 is translated a greater distance (D2) from the fold line 1609>D1 ). The array of coupling lightguides extending in the extension direction 1614 and positioned along the fold line is staggered in the lateral direction (x-direction) by a line 1609 in the + y-direction from the fold point 1608 due to the change in radius of curvature.

FIG. 8 is a top view of one embodiment of a light input-coupler 1700 comprising a film-based light guide 107 with staggered coupling light guides 1701, 1702, 1703, 1704, and 1705. In this embodiment, the coupling light guides 1701, 1702, 1703, 1704 and 1705 extend from the light guide 107 in an extension direction 1614 (parallel to the-x direction) and fold in the + z and-y directions around the 45 degree angled teeth 1707 of the oppositely positioned holding element 3301. The

coupling lightguides

1701, 1702, 1703, 1704 and 1705 are folded along fold line 1609, shown for clarity to extend across cut line 1706 where the coupling lightguides would normally be cut (or the film-based lightguides would be cut from film-based lightguide 107 first during the manufacturing process). In this embodiment, the

coupling lightguides

1701, 1702, 1703, 1704 and 1705 have staggered light input surfaces 1708 that translate in a direction 1614 of extension perpendicular to the fold line 1609. The first coupling light guide 1701 translates a first translation distance D1 from the fold line 1609. The fifth coupling light guide 1705 is translated a fifth translation distance D5 from the fold line 1609. Because the radius of curvature of the fifth coupling light guide 1705 is greater than the radius of curvature of the first coupling light guide 1701, the fifth translation distance D5 is greater than the first translation distance D1.

FIG. 9 is a top view of one embodiment of a light emitting device 2300 including a plurality of coupling light guides 104, each coupling light guide 104 having a plurality of first reflective surface edges 3908 and a plurality of second reflective surface edges 3907 within each coupling light guide 104. In the embodiment shown in fig. 9, three light sources 102 are disposed to couple light into each light input edge 204 defined at least in part by each first and second reflective surface edges 3908 and 3907.

FIG. 10 is an enlarged perspective view of the coupling light guide 104 of FIG. 9 with the light input edge 204 disposed between the first reflective surface edge 3908 and the second reflective surface edge 3907. The light source 102 is omitted from fig. 10 for clarity.

FIG. 11 is a top view of one embodiment of a film-based light guide 4900 that includes an array of | taper | [ c1] coupling light guides 4902 formed by cutting regions in light guide 107. The array of tapered coupling light guides 4902 forms an array dimension length d1 in the first direction (the y-direction as shown) that is less than the parallel dimension length d2 of the light emission region 108 of the light guide 107. Compensation region 4901 is defined within film-based light guide 4900 and does not include a tapered coupling light guide 4902 extending therefrom. In this embodiment, the compensation region 4901 provides a volume in the y-direction of sufficient length to place a light source (not shown) so that the light source does not extend beyond the lower edge 4903 of the light guide 107. The light-emitting region 108 may have a higher density of light extraction features (not shown) to compensate for the lower input flux received directly into the light-emitting region 108 from the tapered coupling light guide 4902. In one embodiment, although the light extraction features within the compensation region 4901 of the light emission region 108 receive a lower level of luminous flux, a substantially uniform illumination or luminous flux output per unit area in the light emission region 108 is achieved, for example, by increasing the light extraction efficiency or area ratio of the light extraction feature area to the area of the region without light extraction features within one or more of the compensation regions 4901, increasing the width of the light mixing region 105 between the tapered coupling light guide 4902 and the light emission region 108, decreasing the light extraction efficiency or average area ratio of the light extraction features to the area without light extraction features in one or more of the light emission regions 108 outside of the compensation region 4901, or any suitable combination thereof.

Fig. 12 is a perspective top view of one embodiment of a light emitting device 5000, the light emitting device 5000 comprising the film-based light guide 4900 and light source 102 shown in fig. 11. In this embodiment, the tapered coupling light guide 4902 is folded in the y-direction towards the light source 102 such that the light input edge 204 of the tapered coupling light guide 4902 is arranged to receive light from the light source 102. Light from light source 102 propagates through tapered coupling light guide 4902, exits tapered coupling light guide 4902, and enters light emission region 108 which generally propagates in the + x direction while expanding in the + y and-y directions. In this embodiment, the light sources 102 are arranged in regions that do not include the tapered coupling light guide 4902, and the light sources 102 do not extend beyond the lower edge 4903 of the light emitting device 5000 in the y-direction. The light emitting device 5000 has a shorter overall width in the y-direction as it does not extend beyond the lower edge 4903. Further, when the tapered coupling light guide 4902 and light source 102 are folded along fold (or curved) line 5001 below the light emission region 108 (the-z direction then the + x direction), the light emitting device 5000 may remain shorter in the y direction (shown in fig. 12) by dimension d3.

FIG. 13 is a top view of one embodiment of a film-based light guide 5800 that includes an array of directionally coupled light guides 5801 that are parallel to a first direction 5806 that makes an angle with a second direction 5807 that is a coupled light guide orientation angle 5808 that is perpendicular to the direction of the array of directionally coupled light guides 5801 at a light mixing region 5805 (the y-direction). The array of directionally coupled light guides 5801 includes tapered light collimating lateral edges 5803 adjacent to the light input surface 5804 and light turning lateral edges 5802 between the light input surface and the light mixing region 5805 of the film-based light guide 107. In this embodiment, when the array of directional coupling lightguides 5801 is folded, light from a light source (not shown) arranged to emit light into the light input surface 5804, during propagation, has its optical axis parallel to the first direction 5806 of the array of directional coupling lightguides 5801, and the optical axis is turned by the light turning lateral edge 5802 such that the optical axis is substantially parallel to the second direction 5807, which is perpendicular to the direction (y-direction) of the array of directional coupling lightguides 5801 at the light mixing region 5805. In this embodiment, when the directionally coupled light guide 5801 is folded, then the light source may be positioned between planes that include the lateral edges (5809, 5810) of the light guide 107 (parallel to the z-direction), such that a device or display that includes a light emitting apparatus having a film-based light guide 5800 does not require a large frame or border area that extends significantly beyond the lateral edges (5809, 5810) of the film-based light guide in the y-direction (folded once or when the array of directionally coupled light guides 5801 is folded and the light source, the array of directionally coupled light guides 5801, and the light mixing area 5805 are folded behind the light emitting area 108 of the film-based light guide 107). The array of directional coupling lightguides 5801 allows the light sources to be located between planes that include lateral edges (5809, 5810) of the film-based lightguide, and the light turning lateral edges 5802 redirect the optical axis of the light toward a second direction 5807 that is perpendicular to the direction of the array of directional coupling lightguides 5801 (the y-direction) on the light mixing region 5805, such that when light is extracted by the light extraction features, the optical axis of the light is oriented substantially parallel to the second direction 5807 (not shown) and the light redirecting surface is oriented substantially parallel to the array direction of the array of directional coupling lightguides 5801 (the y-direction).

FIG. 14 is a cross-sectional side view of one embodiment of a spatial display 3600, the spatial display 3600 including front light 3603 optically coupled to a reflective spatial light modulator 3601. Front light 3603 includes a film-based light guide 3602 having light extraction features 1007 that direct light to a reflective spatial light modulator 3601 at an angle near the surface normal of reflective spatial light modulator 3601. In one embodiment, reflective spatial light modulator 3601 is an electrophoretic display, a micro-electromechanical systems (MEMS) based display, or a reflective liquid crystal display. In an embodiment, light extraction features 1007 direct one of 50%,60%,70%,80%, and 90% of the light exiting front light 3603 to reflective spatial light modulator 3601 at an angle in the range of 60 to 120 degrees from the light emitting surface of front light 3603.

FIG. 15 is a cross-sectional side view of one embodiment of a light emitting display 1550 having a film-based light guide 1551 physically coupled to a flexible display connector 1556. In this embodiment, reflective spatial light modulator 1559 comprises bottom substrate 1554 and thin film based light guide 1551 is a top substrate. Light 1552 emitted by light source 102 physically coupled to flexible display connector 1556 enters thin film based light guide 1551 and is redirected by light extraction features 1561 to active layer 1553 where light 1552 is reflected and passes through thin film based light guide 1551 and overclad layer 1557 and exits light emitting display 1550.

FIG. 16 is a perspective view of one embodiment of a light emitting apparatus 3800 comprising a film-based light guide 3802 physically coupled to a flexible display connector 1556 for a reflective spatial light modulator 1559, and a light source 102 disposed on a circuit board 3805 physically coupled to the flexible display connector 1556. In this embodiment, the reflective spatial light modulator 1559 includes an active layer 1553 located between a bottom substrate 1554 and a top substrate 1650. The top substrate 1650 of the reflective spatial light modulator 1559 is optically coupled to the thin film based light guide 3802 using an adhesive cladding layer 3806.

FIG. 17 is a top view of one embodiment of a thin-film based light guide 3900 comprising an array of coupling light guides 3901, 3902, 3903, 3904, 3905 extending from a light guide region 106 of a light guide 107. The first coupling light guide 3901 has an edge separation distance (Es) from a lateral edge 3906 of an adjacent side of the thin-film based light guide 3900. In this embodiment, the separation distances (Cs 1, cs2, cs3, cs 4) of the coupling lightguides along the sides of the film-based lightguide are different. A first coupling light-guide separation distance (Cs 1) between the first and second coupling light-

guides

3901 and 3902 is greater than a second separation distance (Cs 2) between the second and third coupling light-

guides

3902 and 3903. The third coupling light-guide separation distance (Cs 3) between the third coupling light-guide 3903 and the fourth coupling light-guide 3904 is greater than the fourth separation distance (Cs 4) between the fourth coupling light-guide 3904 and the fifth coupling light-guide 3905. As shown in fig. 17, cs1> Cs2> Cs3> Cs4, however, the varying pitch need not decrease continuously along the sides of the film-based light guide 107, and other increasing, decreasing, or varying spacing distances may be used in other embodiments.

Fig. 18 is a perspective view of one embodiment of a light input coupler and light guide 3300, the light guide 3300 including a relative position-retaining element 3301 disposed proximal to a linear fold region 2902. In this embodiment, the relative position maintaining element 3301 has a cross-sectional edge 2971 for the at least one coupling light guide 104 in a plane (the xy plane as shown) parallel to the light transmissive film surface 2970 disposed proximate to the linear fold region 2902, the linear fold region 2902 including a substantially linear portion 3303 for the at least one coupling light guide 104 oriented at an angle 3302 greater than 10 degrees from a direction 2906 parallel to the linear fold region direction 2906. In one embodiment, the substantially linear portion 3303 is disposed at an angle of about 45 degrees from parallel to the linear fold region 2902.

Fig. 19 is a perspective view of one embodiment of a relative position retaining element (RPME) 9100, the relative position retaining element 9100 comprising a ridge 9101 defined within a ridge region 9122 and angled teeth 9107 extending from the ridge 9101 in a tooth extension direction 9109 (parallel to the + x direction) orthogonal to the alignment direction 9111 (parallel to the y direction) of the angled teeth 9107. In this embodiment, the angled teeth 9107 include a first edge 9108 oriented at a first tooth edge angle 9110 from a tooth extension direction 9109. A second edge 9105 oriented in the xy-plane at a second tooth edge angle 9104 relative to the tooth extension direction 9109. The first edge 9108 and the second edge 9105 have a curved edge profile 9102 in the z-direction. The curved edge profile 9102 may reduce the likelihood of tearing the coupling light guide (not shown), for example, by eliminating acute angles between the first and

second edges

9108, 9105 and the top and

bottom surfaces

9112, 9113 of RPME 9100. The curved edge profile 9102 allows for a larger contact surface area (curved edge profile 9102) for a coupling light guide (not shown) folded around the edge, thereby distributing the force generated by the tension over a larger area than a 90 degree flat edge (where the force is generally concentrated along a linear edge interface between the surfaces) and thus the coupling light guide is less likely to tear. The intersection between the first edge 9108 and the second edge 9105 is a curved intersection 9103 in a cross-section parallel to the x-y plane. The curved intersection 9103 prevents sharp intersections between the first edge 9108 and the second edge 9105 that may cause tears in the coupling light guide during assembly, folding, or stacking. In the embodiment shown in fig. 19, the angled teeth 9107 have a truncated portion 9106 between the ridge 9101 and the first edge 9108. The truncated portions 9106 of the angled teeth 9107 provide a higher angular and/or positional tolerance for the coupling lightguides (not shown) to position themselves against the first edge 9108 as they are folded about the angled teeth 9107. For example, in this embodiment, the intersections between the first and

second edges

9108, 9105 and the coupling light guides do not form corners, and the coupling light guides can slide along the first edge 9108 and over the first edge 9108 (toward the ridge 9101) without being stopped by the corners of the intersection between the first and

second edges

9108, 9105 at the ridge 9101.

Fig. 20 is a top view of one embodiment of a film-based light guide 9000, which includes coupled light guides 9001, 9002, 9003, 9004, 9005, 9006, 9007, and 9008 cut from light guide 107 and separated from light emission region 108 by light mixing region 9010. The light mixing region 9010 extends beyond the distal lateral edge 9014 of the light emitting region 108 in a first direction 9013 orthogonal to the direction of extension 9012 of the coupling light guides 9001, 9002, 9003, 9004, 9005, 9006, 9007, and 9008. Light 9015 propagating through the eighth coupling light guide 9008 (shown as light 9015 propagating before the coupling light guides 9001, 9002, 9003, 9004, 9005, 9006, 9007, and 9008 folded in the + z and-y directions for clarity) is reflected from the angled light mixing region lateral edge 9011 toward the light emission region 108. The angled light mixing region lateral edge 9011 is oriented at a first extended orientation angle 9019 from the extension direction 9012 to direct light 9015 from the light mixing region 9010 to the light emission region 108 of the light guide 107. In this embodiment, the light 9015 is totally internally reflected from an inner light guiding edge 9016 formed by the cut in the light guide 107 to be guided to a more distal region 9017 of the distal lateral edge 9014 of the light emission region 108 that is closer to the light emission region (a region that is further from the light input surfaces (not shown) of the coupling light guides 9001, 9002, 9003, 9004, 9005, 9006, 9007 and 9008 that are folded and stacked in the + z and-y directions). In this embodiment, the eighth coupling light guide 9008 may direct more light to the far region 9017 of the light emission region 108 to increase the luminous flux to the far region to compensate for the reduced luminous flux relative to the near region 9018 of light due to more flux absorbed in the longer coupling light guides (e.g., the eighth and seventh coupling light guides 9008, 9007) as compared to the shorter coupling light guides (e.g., the first and second coupling light guides 9001, 9002).

Fig. 21 is a side cross-sectional view of a portion of one embodiment of a spatial display 9200 illuminated by a front light 9211 that includes a film-based light guide 9210 optically coupled to a reflective spatial light modulator 3601 within an active area 9208 of the reflective spatial light modulator 3601 using an adhesive 9206 (e.g., an acrylate-based pressure sensitive adhesive). After exiting the light source (not shown) and folding the stacked coupling light guide (not shown), light 9212 exits light mixing regions 9209 of thin-film based light guide 9210 and is reflected from light extraction features 1007 on the surface of thin-film based light guide 9210 toward reflective spatial light modulator 3601 at an angle close to surface normal 9202 of reflective spatial light modulator 3601. Light 9212 reflects back from the reflective spatial light modulator 3601 and passes through the thin film based light guide 9210 and back to the spatial display 9200. A scratch-resistant hardcoat 9204 on hardcoat substrate 9203 protects the outer top surface 9207 of spatial display 9200 and is optically coupled to thin film based light guide 9210 using adhesive 9205 (e.g., silicone based pressure sensitive adhesive). In this embodiment, the adhesive 9205 between the hard coat substrate 9203 and the thin film based light guide 9210 and the adhesive 9206 between the thin film based light guide 9210 and the reflective spatial light modulator 3601 also serve as cladding layers for the thin film based light guide 9210 and are shown as being partially coated in areas extending in the active area of the display, but not completely coated over the light mixing areas 9209 of the thin film based light guide 9210.

Fig. 22 is a top view of an embodiment of a light emitting device 9250 in which a first light input coupler 9255 and a second light input coupler 9256 are positioned on opposite sides of the light guide 107. The first light input coupler 9255 includes a first stacked array of coupling light guides 9261. The first light input coupler 9255 further comprises a first light source 9251, the first light source 9251 being arranged to emit light to the first light input surface 9259 of the first stacked array of coupling light guides 9261, and a first photodetector 9252 for receiving light from the first light input surface 9259. The second light input coupler 9256 includes a second stacked array of coupling light guides 9262, the second light input coupler 9256 further includes a second light source 9253, the second light source 9253 positioned to emit light to a second light input surface 9260 of the second stacked array of coupling light guides 9262, and a second photodetector 9254 positioned to receive light from the second light input surface 9260. In this embodiment, the second photodetector 9254 may detect light from the first light source 9251 that propagates through the first stacked array of coupling light guides 9261, the first light mixing region 9257, the light emitting region 108, the second light mixing region 9258, and the second stacked array of coupling light guides 9262. Similarly, the first photodetector 9252 may detect light from the second light source 9253 that propagates through the second stacked array of coupling light guides 9262, the second light mixing region 9258, the light emitting region 108, the first light mixing region 9257, and the first stacked array of coupling light guides 9261. For example, in one embodiment, the first light source 9251 is turned on briefly while the second light source 9253 is turned off, and the second photodetector 9254 measures the intensity of the received light after passing through the region of the light guide 107. By comparing the relative intensity of light over time, the power provided to the first light source 9251 may be increased to account for degradation in light output of the first light source 9251 and/or an increase in light absorption by the film-based light guide 107 (e.g., the film turning yellow over time), such that the light output from the light-emitting region 108 of the light-emitting device 9250 remains substantially constant (e.g., a constant luminance or a constant luminous intensity of the light-emitting region 108 at zero degrees from a surface of the light-emitting region 108 perpendicular to the surface). Similarly, the relative intensity of light reaching the first photodetector 9252 from the second light source 9253 may be evaluated, and the power provided to the second light source 9253 may be adjusted accordingly to maintain a substantially constant light output from the light emitting region 108 of the light emitting device 9250. In one embodiment, the first light source 9251 comprises a light emitting diode that emits light at a first wavelength bandwidth; the second light source 9253 includes light emitting diodes that emit light of a second wavelength bandwidth. In another embodiment, the first photodetector 9252 comprises a light emitting diode driven in a reverse mode to detect light intensity within a second wavelength bandwidth; and/or the second photodetector 9254 comprises a light emitting diode driven in a reverse mode to detect light intensity within the first wavelength bandwidth.

Fig. 23 is a top view of one embodiment of a thin film based light guide 9300 comprising an array of coupling light guides 9301, 9302, 9303, 9304, 9305, 9306, and 9307 in an array direction 9313 extending from the light guide 107, extending in an extension direction 9312 from the light guide 107 and separated from the light emitting region 108 by a light mixing region 9310. The film-based light guide 9300 also includes a sacrificial coupling light guide 9308, the sacrificial coupling light guide 9308 including perforated lines 9351, the perforated lines 9351 being defined by a linear array of perforations 9350 cut out from the light guide 107. Perforated line 9351 separates top cover region 9353 from side cover region 9352. In this embodiment, the distal lateral edge 9354 of the sacrificial coupling light guide 9308 extends beyond the lateral edge 9356 of the light emitting region 108 and includes an angled edge 9355. Furthermore, the sacrificial coupling light guide 9308 does not extend beyond the seventh coupling light guide 9307 in the direction of extension 9312.

Fig. 24 is a perspective view of the film-based light guide 9300 of fig. 23, with an array of coupling light guides 9301, 9302, 9303, 9304, 9305, 9306, and 9307 folded and stacked in the-y direction and in the + z direction to form a light input surface 9382 to receive light from a light source (not shown). Sacrificial coupling light guides 9308 are also folded in the-y and + z directions such that the capping region 9353 is positioned above the stack of coupling light guides 9301, 9302, 9303, 9304, 9305, 9306, and 9307. The side cover region is curved 9352 in the-z direction along perforated line 9351 such that side cover region 9352 is positioned adjacent to lateral edges 9381 of coupling light guides 9301, 9302, 9303, 9304, 9305, 9306, and 9307. Since the light guide 9308 does not extend beyond the seventh coupling light guide 9307 in the direction of extension 9312 prior to folding (as shown in fig. 23), the sacrificial coupling light guide 9308 does not extend to the light input surface 9382 after folding and does not receive a significant amount of light from a light source (not shown) located near the light input surface 9382. Light that is intentionally or unintentionally coupled into the sacrificial coupling light guide 9308 can be guided to the light emitting region 108 by total internal reflection from the angled edge 9355. The angled edge 9355 of the sacrificial coupling light guide 9308 allows the side cap region 9352 to fold down (-z direction) without interfering with the folded region 9383 of the sacrificial coupling light guide 9308. In this embodiment, the sacrificial coupling light guide 9308 can protect the top of the coupling light guides 9301, 9302, 9303, 9304, 9305, 9306, and 9307, the seventh coupling light guide 9307, and the lateral edges 9381. In another embodiment, a wrap (not shown) extends around the top cover region 9353 and the side cover region 9352 of the sacrificial coupling light guide 9308 such that the wrap does not couple light out of the top of the coupling light guides 9301, 9302, 9303, 9304, 9305, 9306, and 9307, the seventh coupling light guide 9307, or the lateral edge 9381.

Fig. 25 is a cross-sectional side view of a portion of one embodiment of a spatial display 9600 illuminated by front light 9604 including a film-based light guide 9610. The film-based light guide 9610 is optically coupled to a color reflective display 9622, which includes a color filter substrate 9606, a color filter layer 9611, and a reflective spatial light modulator 9621. In this embodiment, the film-based light guide 9610 is adhered and optically coupled to the color reflective display 9622 using a light transmissive adhesive 9620 (e.g., an optically clear pressure sensitive adhesive) to adhere the film-based light guide 9610 to the color filter substrate 9606 in the active area 9608 of the color reflective display 9622. The color filter layer 9611 includes an array of first and

second color filters

9601 and 9602 separated by non-active areas 9603 (areas without the first or second color filters 9601 or 9602) of the color filter layer 9611. Light 9623 after exiting the light source (not shown) and the folded stack-coupling light guide (not shown) propagates through the front light 9604, exits the film-based light guide 9610 by reflecting from light extraction features 1007 on the surface of the film-based light guide 9610 toward the color reflective display 9622 at an angle near the surface normal 9607 of the color reflective display 9622. Due to the physical and optical characteristics (e.g., position and facet angle) of the light extraction features 1007, the light 9623 is directed toward the first color filter 9601 and the second color filter 9602. In one embodiment, the light 9623 does not pass through the non-active areas 9603 of the color filter layer 9611. In another embodiment, by aligning the light extraction features 1007 with the first and

second color filters

9601 and 9602 and directing the light 9623 through the first and

second color filters

9601 and 9602 at an angle near the surface normal 9607 of the color reflector 9622, the light 9623 is not directed to inactive areas 9603 of the color filter layer 9611 where it may be absorbed. In the embodiment shown in fig. 25, a scratch-resistant hardcoat 9204 on hardcoat substrate 9203 protects the outer top surface 9207 of spatial display 9600 and is optically coupled to film-based light guide 9610 using an adhesive 9205 (e.g., silicone, pressure sensitive adhesive-based). In an embodiment, the adhesive 9205 between the hard coat substrate 9203 and the thin film based light guide 9610 and the light transmissive adhesive 9620 between the thin film based light guide 9610 and the color filter substrate 9606 also serve as cladding layers for the thin film based light guide 9610 in the active area 9608 of the color reflective display 9622.

Fig. 26 is a top view of one embodiment of a light emitting device 9400 that includes a first light input coupler 9407 that couples light into a secondary display light emitting region 9402 of a thin film based light guide 107. The light emitting device 9400 also includes a second 9408 and a third 9409 light input coupler that couple light into the main display light emitting area 9401 of the thin film based light guide 107. An inner light guide edge 9410 defined by a cut 9412 in the light guide 107 is located between the secondary display light emitting region 9402 and the primary display light emitting region 9401 to reflect a portion of light that would otherwise travel from the secondary display light emitting region 9402 to the primary display light emitting region 9401 or from the primary display light emitting region 9401 to the secondary display light emitting region 9402. In another embodiment, a light absorbing material is optically coupled to the film-based light guide 107 in the region between the secondary display light emission region 9402 and the primary display light emission region 9401 to absorb light to be coupled between the regions. For example, in one embodiment, a black plastic strip or a reflective aluminum strip is positioned within the cut 9412.

Fig. 27 is a top view of one embodiment of a light emitting device 9500 including a primary display 9501 and a secondary display 9502 illuminated by the light emitting device 9400 of fig. 26. In this embodiment, the sub-display 9502 may provide information having different usage patterns or illumination patterns. For example, in one embodiment, the secondary display 9502 provides

icons

9503 and 9504, which may be illuminated for a shorter period of time than the primary display 9501, or may be illuminated by a single white light emitting diode in the first light input coupler 9407, as opposed to, for example, red, green, and blue light emitting diodes providing greater gamut illumination in the second light input coupler 9408 and the third light input coupler 9409. In another embodiment, the primary display and the secondary display are illuminated using a first film-based light guide and a second film-based light guide (separated at least in their light emission regions), respectively.

Figure 28 is a perspective view of one embodiment of a wrapped light guide 9900 including a film-based light guide 107 and a light input coupler 9901, the light input coupler 9901 including an array of coupling light guides 9906 extending from the light guide 107, the array of coupling light guides 9906 folded and stacked defining a light output surface 9903. The coupling light guide 9906 is located within a cavity 9905 of the light input coupler housing 9902. Conformal wrapping material 9904 is inserted into the cavity 9905, which hardens or solidifies to hold their relative positions, protects the coupling light guide 9906, and provides a low index cladding layer for the coupling light guide 9906. In one embodiment, after the light input-coupler housing 9902 is positioned around the coupling light guide 9906, a conformal wrapping material 9904 is injected into the cavity 9905 of the light input-coupler housing 9902. Also in this embodiment, the light input surface 9903 of the coupling light guide 9906 extends through the opening 9907 of the light input coupler housing 9902 so that the light input surface 9903 can receive light input.

Fig. 29 is a cross-sectional side view of a portion of one embodiment of a light emitting device 10000 comprising a light source 102, a light guide 107 and a light input coupler 10009. The light input coupler 10009 includes an array of coupling lightguides 104 extending from the lightguide 107 that are folded around RPME10008 and stacked together to define with the ends of the coupling lightguides 104 a light input surface 10003 positioned to receive light from the light source 102. The coupling lightguides 104 are aligned laterally (x-direction) against the ridge edge 10018 of RPME 10008. The light emitting device 10000 further comprises a flexible wrapper 10001, the flexible wrapper 10001 being positioned around the array of folded, stacked coupling light guides 104. In one embodiment, the flexible wrap 10001 can physically protect the coupling light guide 104 from scratches or contamination, maintain the relative position of the coupling light guide 104 (e.g., hold it in a compressed stack to occupy a small volume), couple light propagating within the cladding layer of the light guide 107 out of the light guide 107, or prevent stray light from exiting the light input coupler 10009. The wrap 10001 comprises an alignment guide hole 10002 in the alignment guide area 10017, which alignment guide hole 10002 can be used to position the wrap 10001 in a folding device (not shown) such that it can be aligned with a component of the light guide 107, the optical input coupler 10009 or the optical input coupler 10009 during assembly. The wrap 10001 also includes perforations 10016 that can be used to remove an alignment guide area 10017 of the wrap 10001 that includes an alignment guide aperture 10002. For example, in one embodiment, the alignment guide area 10017 of the wrap 10001 is removed after the wrap is adhered. The light emitting apparatus 10000 further includes: a first surface 10011 of the light guide 107, on a side of the light guide 107 opposite the stack of coupling light guides 104, a surface 10012, comprising a lateral edge 10010 of the coupling light guide 104; a third surface 10013 comprising an outer surface of the coupling light guide 104 in the stack of coupling light guides 104 furthest from the light guide 107; and a fourth surface 10014 of the light guide 107 on the same side of the light guide 107 as the stack of coupling light guides 104. In one embodiment, the flexible wrap 10001 comprises a tape having an adhesive on the inner surface 10015 that adheres to one or more surfaces selected from the group consisting of: a first surface 10011, a second surface 10012, a third surface 10013, and a fourth surface 10014. In one embodiment, the wrap 10001 adheres to the first surface 10011 and the fourth surface 10014 and holds the coupling light guide 104 together and towards the light guide 107 in the z-direction. In one embodiment, the wrap 10001 does not contact the second surface 10012 and there is an air gap between the lateral edges 10010 of the coupling light guide 104 such that the wrap 10001 does not couple light out of the lateral edges 10010 of the coupling light guide 104.

FIG. 30 is a perspective view of one embodiment of a relative position retaining element (RPME) 9800, the relative position retaining element 9800 including a ridge 9801 defined within a ridge region 9822 and angled teeth 9807 extending from the ridge 9801 in a tooth extension direction 9809 (parallel to the (+ x direction) with the tooth extension direction 9809 orthogonal to the direction of arrangement 9811 (parallel to the y direction) of the angled teeth 9807. The RPME9800 includes a notch 9823 parallel to the tooth extension direction 9809 in the ridge region 9822 between the angled teeth 9807 such that the RPME9800 can be broken or fractured along the notch 9823. In another embodiment, the RPME9800 includes one or more separation mechanisms defined by perforations (not shown) in the ridge region 9822 of the RPME9800 such that the RPME9800 can be broken or fractured along the one or more perforations.

Fig. 31, 32 and 33 are perspective views of one embodiment of a Relative Position Maintaining Element (RPME) 10100, the relative position maintaining element 10100 including a ridge 10106 and angled teeth 10101 extending in a tooth extension direction 10109 (parallel to the + y direction) orthogonal to an array direction 10110 (parallel to the x direction) of the angled teeth 10101. The angled teeth 10101 include a first edge 10104 and a second edge 10105. The first edge 10104 has a curved edge profile in the z-direction. In this embodiment, the angled teeth 10101 extend from the ridges 10106 that connect them together, and are positioned below the ridges 10106 (best shown in FIG. 33, where the angled teeth 10101 can be seen to extend beyond the ridges in the x-y plane). By starting with the angled tooth 10101 from below the ridge 10106, the volume of RPME10100 is reduced because the length of RPME10100 in the y-direction is reduced relative to the tooth 10101 extending from the transverse edge 10108 of the ridge 10106 at an angle. In this embodiment, the angled teeth 10101 ridges 10106 of RPME10100 are physically coupled without the ridges extending beyond the angled teeth 10101 in the xy plane. RPME10100 further includes a land region 10102 on which one or more elements of a light emitting device (e.g., a coupling light guide, a light source, collimating optics, and a reflective film) may be adhered to RPME10100.

FIG. 34 is a cross-sectional side view of one embodiment of a light emitting device 3400 comprising a light input coupler 101, a thin film based light guide 107, the thin film based light guide 107 comprising a core layer 601 optically having a core index of refraction nDL coupled to a reflective spatial light modulator 3408 using a first pressure sensitive adhesive layer 3407 comprising a first material having a first index of refraction nD 1. A light source 1102 having an optical axis parallel to the + y direction (into the page) is positioned to emit light into the folded stack of coupling lightguides 104. The film-based light guide 107 has a plurality of low angle guiding features 3503 on a lower surface 3413 of the core layer 601 of the film-based light guide 107 and is optically coupled to the light turning film 3403 on an upper surface 3414 of the core layer 601 using a second pressure sensitive adhesive layer 3412 of a second material having a second index of refraction nD 2. The light turning film 3403 includes a plurality of light turning features 3401 on a top surface 3415 of the light turning film 3403 opposite the second pressure sensitive adhesive layer 3412. A third pressure sensitive adhesive layer 3405 optically couples a cover layer 3406 (e.g., a protective PET film or a touch screen film) to the light guiding film 3403 on a portion of the top surface 3415, forming air gaps 3416 over the light turning features 3401. The light-mixing region 105 is located between the light input-coupler 101 and the light-emitting region 108 of the light-emitting device 3400. The opaque layer 3411 is optically coupled to the film-based light guide 107 in the light mixing region 105 using a second pressure sensitive adhesive layer 3412. In this embodiment, the opaque layer 3411 is a light absorbing layer that absorbs at least 70% of the light in the wavelength range of 400 nanometers to 700 nanometers that reaches the opaque layer through the second pressure sensitive adhesive layer 3412. In this embodiment, first light 3409 and second light 3410 from light source 1102 propagate through coupling light guide 104 within light input coupler 101, are totally internally reflected within core layer 601 of film-based light guide 107, and propagate through light mixing region 105 and into light emission region 108 of film-based light guide 107. The first light 3409 is reflected from the low angle guiding features 3503 into the core layer 601 of the light guide at a second angle that is less than the angle of incidence, with an average total divergence angle that is less than 20 degrees. In this embodiment, the second angle is less than the critical angle of the interface between the core layer 601 and the second pressure sensitive adhesive layer 3412. In this embodiment, nDL > nD2> nD1, such that because the refractive index nD2 of the second pressure sensitive adhesive layer 3412 is greater than the refractive index nD1 of the first photosensitive adhesive layer 3407, the first light 3409 and the second light 3410 preferentially escape the total internal reflection conditions within the core layer 601 of the film-based light guide 107 at the upper surface 3414 of the core layer 601. After transmission from the core layer 601 into the second pressure sensitive adhesive layer 3412, the first light 3409 propagates into the light turning film 3403 and is totally internally reflected from the light turning features 3401 inside the light turning film 3403 to an angle within 30 degrees of the thickness direction (parallel to the z-direction in this embodiment) of the film-based light guide 107. The first light 3409 then propagates back through the light turning film 3403, the second pressure sensitive adhesive layer 3412, the core layer 601, and the first pressure sensitive adhesive layer 3407, reflects off the reflective spatial light modulator 3408, passes through the above layers in reverse order, does not interact with the light turning features 3401 a second time, but is emitted from the light emitting region 108 of the light emitting device 3400.

After being redirected by the low angle directing features 3503, the second light 3410 travels from the core layer 601 into the second pressure sensitive adhesive layer 3412 and the light turning film 3403. The second light 3410 does not intersect the light turning features 3401 on the first pass, and is totally internally reflected from the top surface 3415 of the light turning film 3403 between the light turning features 3401, and through the light turning film 3403, through the second pressure sensitive adhesive layer 3412, back through the core layer 601, and totally internally reflected at the interface between the core layer 601 and the first pressure sensitive adhesive layer 3407, through the layers in reverse order, and totally internally reflected from the light turning components 3401 in the light turning film 3403 to an angle of 30 degrees from the thickness direction (parallel to the z-direction in this embodiment) of the film based light guide 107. The second light 3410 is further transmitted back through the light turning film 3403, the second pressure sensitive adhesive layer 3412, the core layer 601, and the first pressure sensitive adhesive layer 3407, reflected from the reflective spatial light modulator 3408, and passed through the above layers in reverse order, and emitted from the light emitting device 3400 in the light emitting region 108.

FIG. 35 is a cross-sectional side view of one embodiment of a light emitting apparatus 3500 comprising a light input coupler 101 and a film-based light guide 107, the film-based light guide 107 comprising a core layer 601 of a core material having a core refractive index nDL optically coupled to a reflective spatial light modulator 3408 using a first pressure sensitive adhesive layer 3407 comprising a first material having a first refractive index nD 1. A light source 1102 with an optical axis parallel to the + y direction (into the page) is positioned to emit light into the folded stack of coupling lightguides 104. Film-based light guide 107 includes a plurality of low-angle light directing features 3503 on an upper surface 3414 of its core layer 601, and is optically coupled to light turning film 3403 on the upper surface 3414 of core layer 601 using a second pressure sensitive adhesive layer 3412 of a second material including a second index of refraction nD 2. The light turning film 3403 includes a plurality of light turning features 3401 on a top surface 3415 of the light turning film 3403 opposite the second pressure sensitive adhesive layer 3412. The third pressure sensitive adhesive layer 3405 optically couples a cover layer 3406 (e.g., a protective PET film or a touch screen film) to the light guiding film 3403 on a portion of the top surface 3415, forming air gaps 3416 over the light turning features 3401. The light-mixing region 105 is located between the light input-coupler 101 and the light-emitting region 108 of the light-emitting device 3400. The opaque layer 3411 is optically coupled to the film-based light guide 107 in the light mixing region 105 using a second pressure sensitive adhesive layer 3412. In this embodiment, the opaque layer 3411 is a light absorbing layer that absorbs at least 70% of the light in the wavelength range of 400 nm to 700 nm that reaches the opaque layer 3411 through the second pressure sensitive adhesive layer 3412. In this embodiment, first light 3501 and second light 3502 from light source 1102 propagate through coupling light guide 104 within light input coupler 101, are totally internally reflected within core layer 601 of film-based light guide 107, and propagate through light mixing region 105 and into light emission region 108 of film-based light guide 107. The first light 3501 is refracted at the low angle guiding features 3503 to a new angle that is less than the incident angle, with an average total divergence angle that is less than 20 degrees so that the light propagates out of the core layer 601 of the light guide. In this embodiment, a portion of light from within the core layer 601 that intersects the low angle guidance features 3503 may be transmitted through the low angle guidance features 3503 and a portion may be reflected from the low angle guidance features 3503. In this embodiment, nDL > nD2> nD1, such that a portion of light reflected from low-angle directing features 3503 can be reflected at an overall off-angle of less than 20 degrees, such that it is reflected from the boundary between the core layer 601 and the first pressure sensitive adhesive layer 3407, and exits the core layer 601 at the upper surface 3414 of the core layer 601. After passing through the interface between the core layer 601 and the second pressure sensitive adhesive, the first light 3501 then propagates through the second pressure sensitive adhesive layer 3412 into the light turning film 3403 and is totally internally reflected from the light turning features 3401 in the light turning film 3403 to an angle within 30 degrees of the thickness direction (parallel to the z-direction in this embodiment) of the film-based light guide 107. The first light 3501 then propagates back through the light turning film 3403, the second pressure sensitive adhesive layer 3412, the core layer 601, and the first pressure sensitive adhesive layer 3407, reflects from the reflective spatial light modulator 3408, passes through the above layers in reverse order, does not interact with the light turning features 3401 a second time, and is emitted from the light emitting region 108 of the light emitting device 3500.

After being redirected by the low angle directing features 3503, the second light 3502 propagates through the second pressure sensitive adhesive layer 3412 and into the light turning film 3403. The second light 3502 does not intersect the light turning features 3401 in the first direction on the first pass, passes between the light turning features 3401 from the top surface 3415 of the light turning film 3403 and is totally internally reflected, and passes through the light turning film 3403, through the second pressure sensitive adhesive layer 3412, propagates back through the core layer 601 and is totally internally reflected at the interface between the core layer 601 and the first pressure sensitive adhesive layer 3407, passes back through the above layers in reverse order, and is totally internally reflected from the light turning components 3401 in the light turning film 3403 to within 30 degrees of the thickness direction (parallel to the z-direction in this embodiment) of the film-based light guide 107. The second light 3502 then propagates through the light turning film 3403, the second pressure sensitive adhesive layer 3412, the core layer 601, and the first pressure sensitive adhesive layer 3407, reflects from the reflective spatial light modulator 3408, and propagates back through the above layers in reverse order, and is emitted from the light emitting device 3400 in the light emitting region 108.

FIG. 36 is a perspective view of one embodiment of a light emitting device 3691 including an optical input-coupler 200 having a coupling light guide 104 folded in the-y direction. Light 3692 from light source 102 is directed through phase-compensating optical element 3690, through or along light input edge 204 of coupling light guide 104, and into light input surface 103. A portion of the light from the light source 102 propagates within the coupling light guide 104 and a directional component in the + y direction will be reflected in the + x and-x directions from the lateral edges 203 of the coupling light guide 104 and will be reflected in the + z and-z directions from the coupled upper and lower surfaces. Light propagating within the coupling light guide is redirected by folds 201 in the coupling light guide 104 towards the-x direction and the light emitting area 108 of the light guide 107. In this embodiment, the phase compensating optical element 3690 pre-compensates for phase shifts of light propagating through the coupling light guide 104 and the light guide 107 such that a uniform or predetermined spatial phase output profile of light emitted from the light emitting region 108 of the light emitting device 3691 is achieved.

FIG. 37 is a cross-sectional side view of one embodiment of a light emitting device 3700 that includes a light input coupler 101, a film-based light guide 107, the film-based light guide 107 including a core layer 601 of optically core material having a core refractive index nDL, coupled to a light turning film 3403 on a portion of a top surface 3704 of the light turning film 3403 (such that air gaps 3416 are formed at the light turning features 3401) using a second pressure sensitive adhesive layer 3412, the second pressure sensitive adhesive layer 3412 including a second material having a second refractive index nD 2. The reflective spatial light modulator 3408 is optically coupled to the light turning film 3403 using a third pressure sensitive adhesive layer 3405. The light turning film 3403 includes a plurality of light turning features 3401 on a top surface 3705 of the light turning film 3403 opposite the third pressure sensitive adhesive layer 3405. A light source 1102 having an optical axis parallel to the + y direction (into the page) is positioned to emit light into the folded stack of coupling lightguides 104. Film-based light guide 107 includes low-angle guiding features 3503 on a top surface 3705 of core layer 601 of the plurality of film-based light guides 107 and is optically coupled to cover layer 3406 (e.g., a protective PET film or a touch screen film) using a first pressure sensitive adhesive layer 3407 including a first material having a first index of refraction nD 1.

The light mixing region 105 is located between the light input coupler 101 and the light emitting region 108 of the light emitting device 3700. The opaque layer 3411 is optically coupled to the film-based light guide 107 in the light mixing region 105 using the first pressure sensitive adhesive layer 3407. In this embodiment, the opaque layer 3411 is a light absorbing layer that absorbs at least 70% of the light in the wavelength range between 400 nanometers and 700 nanometers that reaches the opaque layer 3411 through the first pressure sensitive adhesive layer 3407. In this embodiment, first light 3701 from light source 1102 propagates through coupling light guide 104 within light input coupler 101, is totally internally reflected within core layer 601 of film-based light guide 107 and propagates through light mixing region 105 and into light emission region 108 of film-based light guide 107. The first light 3701 is reflected from the low angle guiding features 3503 into the core 601 of the light guide at a second angle less than the angle of incidence, which has an average total divergence angle of less than 20 degrees. In this embodiment, the second angle is less than the critical angle of the interface between the core layer 601 and the second pressure sensitive adhesive layer 3412. In this embodiment, nDL > nD2> nD1, because the refractive index nD2 of second pressure sensitive adhesive layer 3412 is greater than the refractive index nD1 of first pressure sensitive adhesive layer 3412, first light 3701 is caused to preferentially escape the total internal reflection conditions within core layer 601 of film-based light guide 107 from lower surface 3706 of core layer 601. After transmission from the core layer 601 into the second pressure sensitive adhesive layer 3412, the first light 3409 propagates into the light turning film 3403 and is totally internally reflected from the light turning features 3401 in the light turning film 3403 to an angle within 30 degrees of the thickness direction (parallel to the z-direction in this embodiment) of the film-based light guide 107. The first light 3409 then propagates through the third pressure sensitive adhesive layer 3405 and reflects from the reflective spatial light modulator 3408, passes back through the above layers in reverse order, does not interact a second time with the light turning features 3401, and is emitted from the light emitting region 108 of the light emitting device 3400.

FIG. 38 is a top view of a portion of one embodiment of a light emitting device 5600 including an array of coupling lightguides 104 extending from a film-based lightguide 107 (before being folded to receive light from a light source (not shown)) in an extension direction 9312 perpendicular to an array direction 9313 of a linear array of coupling lightguides 104. Note that the coupling lightguides are aligned in an array, and as used herein, "array direction" may refer to the direction in which a side or region moves from a shorter coupling lightguide to a longer coupling lightguide, from a longer coupling lightguide to a shorter coupling lightguide, or from a coupling lightguide at one end to a coupling lightguide at the other end as a linear array along an edge. Thus, array direction 9313 can be one or both of opposite directions (e.g., + y direction and/or-y direction in the example shown in FIG. 38). The light emitting device 5600 further comprises a light guiding region 106, the light guiding region 106 comprising a light mixing region 105, a light guide 107 and a light emitting region 108. The array of coupling lightguides 104 includes an overall width w1 where w1 intersects the lightguide region 106 in an array direction 9313 of the array of coupling lightguides 104. In this embodiment, the light guide 107, the light mixing region 105, the light guide region 106 and the light emitting region 108 include two excess width regions 5601 that extend beyond the coupling light guides 104 in the array direction 9313. Due to the contribution of the excess width region 5601, the light guide 107, the light mixing region 105, the light guide region 106, and the light emitting region 108 have an overall width w2 in the array direction 9313 of the array of coupling light guides that is greater than the overall width w1 of the array of coupling light guides 104 along the array direction 9313 of the coupling light guides 104. The light guide 107 is positioned above the reflective spatial light modulator 3408 and below a light turning film 3403, the light turning film 3403 including an array of light turning features 3401 in the form of grooves (only a few grooves are shown for clarity). Other adhesive layers, cladding layers [ c2], protective layers, etc. as described elsewhere herein may be included, but are not shown in this figure for clarity. The

light

5602, 5603 represents light from similar angles in the coupling lightguide 104, which is less intense (e.g., 10% of the peak intensity) because the light propagating at larger angles to the light emitting region 108 is reduced in intensity as it propagates at about the same angle, extracts light at similar angles from the core layer of the lightguide 107, and reflects the light toward the light turning features 3401 of the film 3403 (as shown in FIG. 37). However, light 5602 travels directly to the light emission region 108 without being reflected from the lateral edge 1502 of the light guide 107, while light 5603 is reflected from the lateral edge 1502 of the light guide 107 and travels to the light emission region 108. As can be seen from fig. 38, the angle hatching is represented as an angle hatching region 5605 in which the luminance of a viewing angle (e.g., perpendicular to the external light emission surface of the display, the + z direction in fig. 38) is lower than that of an adjacent region of the light emission region 108 due to the absence of light (represented by arrow 5604) propagating at an angle similar to that of the

lights

5602 and 5603 from the extra-width region 5601.

FIG. 39 is a cross-sectional side view of one embodiment of a light emitting device 5700 comprising a light input coupler 101, a film-based light guide 107, the film-based light guide 107 comprising a core layer 601 of a core material having a core refractive index nDL optically coupled to a reflective spatial light modulator 3408 using a first pressure sensitive adhesive layer 3407 comprising a first material having a first refractive index nD 1. A light source 1102 having an optical axis parallel to the + y direction (into the page) is positioned to emit light into the folded stack of coupling lightguides 104. Film-based light guide 107 has a plurality of low angle guiding features 3503 on a lower surface 3413 of core layer 601 of film-based light guide 107, optically coupled to light turning film 3403 on an upper surface 3414 of core layer 601 using a second pressure sensitive adhesive layer 3412 film-based light guide comprising a second material having a second index of refraction nD 2. The light turning film 3403 includes a plurality of light directing features 3401 on a top surface 3415 of the light turning film 3403 opposite the second pressure sensitive adhesive layer 3412. The light turning film 3403 further includes a plurality of printed black areas 5702 printed with black patterns that are overprinted on the plurality of white reflective areas 5701 on the lower surface 5703 of the light turning film 3403 in the light emitting region 108. The white reflection region 5701 increases the diffusion of light in the lateral direction ((direction of entering into the page plane (+ y direction) direction of coming out of the page plane (-y direction)) toward an extra-width region (as shown in fig. 38), or reflects light to create a new virtual starting point and a direction of light reflection from the white reflection region 5701, making it indirectly appear to be emitted from the extra-width region, and reduces the visibility of angular shadows (increases relative luminance in the shadow region).

The third pressure sensitive adhesive layer 3405 optically couples a cover layer 3406 (e.g., such as a protective PET film or a touch screen film) to the light turning film 3403 on a portion of the top surface 3415, thereby forming air gaps 3416 at the light turning features 3401. The light-mixing region 105 is located between the light input-coupler 101 and the light-emitting region 108 of the light-emitting device 3400. The opaque layer 3411 is optically coupled to the thin film based light guide 107 in the light mixing region 105 using a second pressure sensitive adhesive layer 3412. In this embodiment, the opaque layer 3411 is a light absorbing layer that absorbs at least 70% of the light in the wavelength range between 400 nanometers and 700 nanometers that passes through the second pressure sensitive adhesive layer 3412 to the opaque layer. In this embodiment, light 5704 from light source 1102 propagates through coupling lightguide 104 within light input coupler 101, is totally internally reflected within core layer 601 of film-based lightguide 107, and propagates through light mixing region 105 and into light emitting region 108 of film-based lightguide 107. The second angle at which light 5704 is reflected from the low angle guiding features 3503 into the core layer 601 of the light guide is less than the angle of incidence by less than the average total deviation angle (e.g., less than 20 degrees therefrom). In this embodiment, the second angle is less than the critical angle of the interface between the core layer 601 and the second pressure sensitive adhesive layer 3412. In this embodiment, nDL > nD2> nD1, light 5704 preferentially escapes the total internal reflection conditions in core layer 601 of film-based light guide 107 on upper surface 3414 of core layer 601 because second refractive index nD2 of second pressure sensitive adhesive layer 3412 is greater than refractive index nD1 of first pressure sensitive adhesive layer 3407. After transmission from the core layer 601 into the second pressure sensitive adhesive layer 3412, the light 5704 is more reflectively scattered in the y-direction (transverse direction) so that a portion of the light 5704 is directed to an extra-width region (as shown in fig. 38). The light 5704 also passes back through the second pressure sensitive adhesive layer 3412 and the core layer 601, and reflects back into the core layer from the interface between the core layer 601 and the first pressure sensitive adhesive layer 3407, propagates into the light turning film 3403, and is totally internally reflected from the light turning features 3401 in the light turning film 3403 to the angle of the film-based light guide 107 (e.g., within 30 degrees from the thickness direction parallel to the z-direction). The light 5704 then propagates through the light turning film 3403, the second pressure sensitive adhesive layer 3412, the core layer 601, and the first pressure sensitive adhesive layer 3407, reflects from the reflective spatial light modulator 3408, and propagates back through the layers in reverse order, does not interact with the light turning features 3401 a second time, and is emitted from the light emitting region 108 in the light emitting device 3400. In another embodiment, alternatively or additionally, a plurality of printed black regions 5702 superimposed on a plurality of white reflective regions 5701 overlying the lower surface 5703 of the light turning film 3403 in the light emitting region 108, the light emitting device 5700 can comprise a light scattering material, such as a thin white ink coating inside the light turning features 3401 (e.g., grooves) of the light guiding film 3403. As with the plurality of printed black regions 5702 overprinted on the plurality of white reflective regions 5701, the light scattering material in the light turning feature 3401 may also increase the diffusion or reflection of light in the lateral direction of the light ((direction into the page plane (+ y direction) and direction out of the page plane (-y direction)) toward the extra width region (as shown in fig. 38) to create a new virtual light origin and direction of light reflected from the white reflective regions 5701 to redirect the light to indirectly appear to originate from the extra width region and reduce the visibility of angular shadows (increase the relative luminance of the shadow regions).

Fig. 40 is a side cross-sectional view of one embodiment of a light emitting device 5900 that includes a depth-varying grooved light turning feature 5901 that varies in depth (the depth-varying grooved light turning feature 5901 in the z-direction has a depth relief or modulation in the z-direction). The light emitting device 5900 is otherwise similar to the light emitting device 5700 of fig. 39, except that the printed white and dark regions (as shown in fig. 39) are replaced, for example, with a varying depth groove light turning feature 5901 as a means of reducing the visibility of angular shadows. Light 5902 reflects in the-z direction from the varying depth grooved light turning feature 5901 toward the reflective spatial light modulator 3408 and also reflects at a larger angle in the xy plane towards the y direction ((light 5902 further diffused in the lateral y direction (into the page of fig. 40)) due to the angle of the surface of the varying depth grooved light turning feature 5901 created by varying the depth of the z direction along the length of the varying depth grooved light turning feature 5901 in the y direction the more light is directed towards the y direction the extra width region (as shown in fig. 38) by diffusing more light in the + y and/or-y direction in the example shown, more light is directed towards the extra width region (as shown in fig. 38) or light can reflect from the varying depth grooved light turning feature 5901 creating a new virtual light origin and direction that makes it appear directly as if it is coming from the extra width region and reducing the visibility of the angular shadow (increasing the relative luminance in the shadow region).

Fig. 41 is a top view of a portion of one embodiment of a light emitting device 6000 including an array of coupling light guides 104 extending from the light guide 107 in an extension direction 9312 perpendicular to an array direction 9313 of the linear array of coupling light guides 104 (before being folded to receive light from a light source (not shown)). The light emitting device 5600 further includes a light guide region 106 that includes a light mixing region 105, a light guide 107 and a light emitting region 108. The coupling lightguides 104 have an overall width w1 and meet the lightguide region 106 in the array direction 9313 of the array of coupling lightguides 104. In this embodiment, the light guide 107, the light mixing region 105, the light guide region 106 and the light emission region 108 include two regions of excess width 5601 extending beyond the coupling light guide 104 in the array direction 9313. Due to the contribution of the excess width region 5601, the light guide 107, the light mixing region 105, the light guide region 106, and the light emitting region 108 have an overall width w2 in the array direction 9313 of the array of coupling lightguides 104 that is greater than the overall width w1 of the array of coupling lightguides 104 in the array direction 9313 of the coupling lightguides 104. The light guide 107 is positioned above the reflective spatial light modulator 3408 and below a light turning film 3403, the light turning film 3403 including an array of light turning features 3401 in the form of grooves (only a few grooves are shown for clarity). The light emitting device 6000 may include other layers described elsewhere herein that are not shown for clarity, such as adhesive layers, cladding layers, and the like. The light 5602, 5603 represents light from a similar angle in the coupling lightguide 104 with a lower intensity (e.g., 10% of peak intensity) because the light at approximately the same angle propagates at a larger angle to the light emitting region 108, is extracted from the core layer of the lightguide 107, and reflects off the light turning features 3401 (shown in FIG. 37) of the light turning film 3403 with a drop in intensity. However, light 5603 travels directly to the light emission region 108 without reflecting from the lateral edge 1502 of the light guide 107, while light 5602 reflects from the lateral edge 1502 of the light guide 107 and travels to the light emission region 108. As can be seen from fig. 41, the potential corner hatching is represented as a corner hatching region 5605, the luminance of which is lower than that of the adjacent region of the light emission region 108 due to the absence of light (represented by an arrow 5604) from the excess width region 5601 traveling at an angle similar to that of the

lights

5602 and 5603. However, the light emitting device 6000 of fig. 41 includes two methods of reducing the visibility of angular shadows. A first method of reducing the visibility of the corner shadow region 5605 includes: a first internal light guiding edge 6001 is added in the light-mixing region 105 outside the extra width region 5601, and a second internal light guiding edge 6002 is added in the light-mixing region 105 within the extra width region 5601. Light 6005 exits the coupling light guide 104 and reflects from a first inner light guiding edge 6001 in a light mixing region outside the excess width region 5601 towards a second inner light guiding edge 6002 in an excess width region 5601 in the light mixing region. The light 6005 then reflects from the second inner light guiding edge 6002 towards the light emission region where it increases the luminance intensity (and reduces visibility) of the corner shaded region 5605. In this first method, light 6005 is directly reflected from the inside of the excess width region 5601 and propagates toward the light emission region, thus increasing the illumination intensity in the angular shaded region. A second method of reducing the visibility of the corner shaded region 5605 includes adding a third internal light guiding edge 6003 outside of the region of excess width 5601 in the light emission region 108 and a fourth internal light guiding edge 6004 outside of the region of excess width 5601 in the light mixing region 105. The light 6006 exits the coupling light guide 104, propagates through the light mixing region 105, and then reflects from the third inner light guide edge 6003 in the light emission region 108 towards the fourth inner light guide edge 6004. The light 6006 then reflects from the fourth inner light guiding edge 6004 towards the light emission region, where it increases the luminous intensity (and reduces visibility) of the corner shaded region 5605. The light 6006 indirectly looks like the position and direction (indicated by the direction of arrow 5604) of the same light emitted from the extra-width region 5601 and corresponding to that originating from the extra-width region 5601 and propagating toward the light emitting region 108.

Figure 42 is a top view of one embodiment of a display 6100 that includes an array of coupling lightguides 104 extending from a film-based lightguide 107 along an extension direction 9312 that is perpendicular to an array direction 9313 of a linear array of coupling lightguides 104 (before being folded to receive light from a light source (not shown)). The film-based light guide 107 also includes a light guide region 106 that includes the light mixing region 105, the light guide 107, and the light emitting region 108. In the present embodiment, the sectional shapes of the light emitting region 108 and the reflective spatial light modulator 3408 in a plane parallel to the xy plane are substantially octagonal. The array of coupling lightguides 104 comprises a total width w1 where they meet the lightguide region 106 in the array direction 9313 of the array of coupling lightguides 104. In this embodiment, the light emitting region 108 extends into two excess width regions 6104 that extend beyond the coupling light guide 104 in the array direction 9313. The reflective spatial light modulator 3408 extends into an excess width region 6104 with respect to the coupling light guide 104 in an array direction 9313 of the array of coupling light guides 104. Due to the contribution of the excess width region 6104, the total width w3 of the light emitting region 108 in the array direction 9313 is greater than the total width w1 of the array of coupling light guides 104 in the array direction 9313. The light guide 107 is positioned above the reflective spatial light modulator 3408 and below a light turning film (not shown) that includes an array of light turning features. The display 6100 may include other layers described elsewhere herein that are not shown for clarity, such as adhesive layers, cladding layers, and the like. In this embodiment, light 6101 from a light source (not shown) propagating through the coupling light guide 104 exits the coupling light guide 104, passes through the light mixing region 105 and reflects from a first inner light guiding edge 6102 positioned in the light emission region 108. After reflecting from the first inner light guide edge 6102, the light 6101 passes through the excess width region 6104 and reflects from the lateral edge 6103 of the light guide 107 in the excess width region 6104. In this embodiment, the first inner light guide edge 6102 laterally spreads the light 6101 in the y-direction to provide illumination in a region of the reflective spatial light modulator 3408 (an excess width region of the reflective spatial light modulator 3408) that extends beyond the width of the array of coupling light guides 104 in the array direction 9313.

FIG. 43 is a top view of one embodiment of a display 6200, the display 6200 comprising

arrays

6201, and 6203 of three sets of coupled light guides 104 extending from a light-emitting region 108 of an octagonal thin-film based light guide 107 in a first direction of extension 6204, a second direction of extension 6205, and a third direction of extension 6205, respectively, wherein the first direction of extension 6204, the second direction of extension 6205, and the third direction of extension 6205 are orthogonal to adjacent sides of a reflective spatial light modulator 3408, wherein adjacent sides of the reflective spatial light modulator 3408 may be orthogonally shaped and/or comprise orthogonally shaped active regions where each set 6201, 6202, and 6303 will illuminate the reflective spatial light modulator as front light, such as shown in FIG. 34. In this embodiment, the display 6200 includes a light turning film (not shown for clarity) over the film-based light guide 107, and the light mixing region 105 and the coupling light guide 104 may be folded behind the reflective spatial light modulator 3408, and the array of coupling light guides 104 may be folded and stacked with their stacked ends positioned to receive light from one or more light sources (not shown), such as light emitting diodes. In similar embodiments, other polygonal shapes (or circular or elliptical) may be used for one or more sides (or arcs), one or more sets of arrays of coupling light guides and light mixing regions, and the direction of extension may be orthogonal to the sides (or arc portions) of the polygon (or circle or ellipse). In this embodiment, the one or more light-mixing regions may be folded a first time at the fold edge substantially parallel to the edge of the reflective spatial light modulator, and they may be folded more than once, wherein the second fold and optional additional folds may be angled rather than parallel to the edge of the reflective spatial light modulator. In one embodiment, the use of multiple folds in an array of one or more sets of light-mixing regions and/or one or more sets of coupling lightguides may cause the ends of the light-mixing regions and/or coupling lightguides of each set to overlap (not necessarily oriented at the same angle) so that they may receive light from a single light source or multiple light sources. The ends of the array of coupling lightguides may be aligned or gathered using origami-type manner light mixing regions and/or other folds of coupling lightguides, and the lengths of the light mixing regions and/or coupling lightguides between groups or within a group may be different to accommodate the longer lengths that may be needed to gather the ends together.

Fig. 44 is a perspective view of one embodiment of a light input coupler 4400 with a coupling light guide 104 folded in the-y direction. Light 4403 from the second light source 4402 is guided into the light input surface 103 through the light input edge 204 of the coupling light guide 104 and has a higher FAWHMLI, e.g., 120 degrees FAWHMLI, at the light input surface 103. Light 4404 from the first light source 4401 is guided into the light collimating element 4405 and exits the light collimating element 4405 through the light input edge 204 of the coupling light guide 104 towards the light input surface 103 and has a lower FAWHMLI, e.g., 40 degrees. In this embodiment, light output from the backlight or display using the light input-coupler 4400 of the thin-film based light guide has a lower FAWHMLI in the y-z output plane when the first light source 4401 emits light and the second light source 4402 does not emit light; light output from the backlight or display using the light input-coupler 4400 of the thin film based light guide has a higher FAWHMLI in the y-z output plane when the second light source 4402 emits light and the first light source 4401 does not emit light. In this embodiment, the FAWHMLI from the light emitting areas of the respective film-based light guides comprising the light input-couplers 4400 can be varied by varying the relative light fluxes output from the first and second

light sources

4401 and 4402.

Fig. 45 is a top view of one embodiment of a light emitting device 4500 that includes a first thin film-based light guide 4501 having a first angular light output profile 4505, the first angular light output profile 4505 being located above a second thin film-based light guide 4502 having a second angular light output profile 4506. The first thin film based light guide 4501 is illuminated by light from a first light source 4503, and the second thin film based light guide 4502 is illuminated by light from a second light source 4504. In this embodiment, the angular light output profile of the light emitting device can be controlled by varying the relative luminous flux output from the first film-based light guide 4501 via the first light source 4503 and the second film-based light guide 4502 via the second light source 4504.

Fig. 46 is a top view of one embodiment of a light emitting device 4600 including a first backlight 4606, the first backlight 4606 having a film-based light guide 4601 with a first angular light output profile 4603 with a lower FAWHMLI in the x-z plane, the first backlight being positioned above a second backlight 4604 with a second angular output profile 4605 and a higher FAWHMLI in the xz plane (e.g., using an edge-lit backlight with a 2 mm thick sheet light guide). Film-based light guide 4601 is illuminated by light from first light source 4602. In this embodiment, the angular light output profile of the light emitting device 4600 (e.g., a backlight including two sub-backlights or a display including two backlights) may be controlled by varying the relative luminous flux output from the first backlight 4606 and from the second backlight 4604 via the first light source 4602.

FIG. 47 is a top view of one embodiment of a display 4700 that includes an array of coupling lightguides 104 (prior to folding to receive light from a light source (not shown)) extending from a film-based lightguide 107 along an extension direction 9312 that is perpendicular to an array direction 9313 of a linear array of coupling lightguides 104. The film-based light guide also includes a light guide region 106 that includes a light mixing region 105, a light guide 107, and a light emission region 108. In the present embodiment, the sectional shapes of the light emitting region 108 and the reflective spatial light modulator 3408 in a plane parallel to the x-y plane are substantially octagonal. In this embodiment, the total width w4 of the light-mixing region 105 at the light-emitting region 108 is less than the total width w1 of the array of coupling lightguides, and the excess width region 4705 is a width that exceeds the total width w4 of the light-mixing region 105 closest to the light-emitting region 108. The array of coupling lightguides 104 includes an overall width w1 where the coupling lightguides 104 meet the lightguide region 106 in the direction 9313 of the array. In the present embodiment, the light emitting region 108 and a portion of the reflective spatial light modulator extend to two excess width regions 4705, the two excess width regions 4705 extending beyond the width w4 of the light mixing region 105 at the light emitting region 108 in the array direction 9313. Due to the contribution of the excess width region 4705, the total width w3 of the light emitting region 108 in the array direction 9313 is larger than the total width w4 of the light mixing region 105 at the light emitting region in the array direction 9313. The light guide 107 is positioned above the reflective spatial light modulator 3408 and below a light turning film (not shown) that includes an array of light turning features. The display may include other layers as described elsewhere herein, such as adhesive layers, cladding layers, etc., which are not shown in fig. 47 for clarity. In this embodiment, light 4704 from a light source (not shown) propagates through the coupling lightguide 104, exits the coupling lightguide 104, enters the light mixing region 105, and is reflected from tapered lateral edges 4701 of the light mixing region 105. Light rays 4704, after reflecting from tapered lateral edges 4701, pass through light mixing region 105 and propagate into excess width region 4705. In this embodiment, the tapered lateral edge 4701 of the light-mixing region 105 spreads the light 4704 laterally in the y-direction to provide illumination for the area of the reflective spatial light modulator 3408 (the portion of the reflective spatial light modulator 3408 in the excess width region 4705) that extends beyond the total width of the light-mixing region 105 at the light-emitting region 108 in the array direction 9313. Similarly, light 4703 from a light source (not shown) propagates through the coupling lightguide 104, exits the coupling lightguide 104, enters the light mixing region 105 and reflects from the tapered lateral edge 4702 of the light mixing region 105. After reflecting from tapered lateral edge 4702, light 4703 passes through light mixing region 105 and propagates into excess width region 4705. In this embodiment, the tapered lateral edge 4701 of the light-mixing region 105 spreads the light 4703 laterally in the y-direction to provide illumination for a region of the reflective spatial light modulator 3408 (a portion of the excess width of the reflective spatial light modulator 3408) that extends beyond the total width of the light-mixing region 105 at the light-emitting region 108 in the array direction 9313. In another embodiment, the lateral edges may be arcuate, tapered, stepped in width, or a combination thereof.

FIG. 48 is a top view of one embodiment of a light emitting device 4800 comprising a thin film based light guide 107, the thin film based light guide 107 comprising a plurality of reflective surfaces 4801 arranged in an array in a light mixing region 105 of the thin film based light guide 4805. The light input-coupler 101 comprises an array of coupling light guides 104 arranged in an array direction 9313 (parallel to the + y-axis), and a light source 102, the light source 102 being arranged to guide light into the coupling light guides 104 through a light input surface 103 comprising input edges of the coupling light guides 104. In this embodiment, each coupling light guide 104 terminates at a boundary edge, and each coupling light guide is folded such that the boundary edges of the coupling light guides are stacked to form the light input surface 103. The light emitting device 4800 also comprises a light guiding region 106, the light guiding region 106 comprising a light mixing region 105 and a light emitting region 108. Light 4802 from light source 102 exits light input coupler 101 and enters light mixing region 105 of thin film based light guide 4805. This light 4802 is spatially mixed with light from the different coupling lightguides 104, and a portion 4803 of the light 4802 is reflected from one or more of the plurality of reflective surfaces 4801 toward the lateral edge 1502 of the thin-film based lightguide 4805 in the light emission region 108. Portion 4803 of reflected light 4802 propagates into light-transmitting zone 108 with non-reflected portion 4808 of light 4802 and exits thin film based light guide 4805 of light-transmitting zone 108 due to light extraction features (not shown). The additional reflection of light 4802 from the array of coupling lightguides 104 by the plurality of reflective surfaces 4801 increases the uniformity of light emitted from the light emitting region 108 in the array direction 9313 of the array (parallel to the + y direction). A surface 4809 of thin film-based light guide 4805 includes a region 4804 defined by a plurality of reflective surfaces 4801, where the plurality of reflective surfaces 4801 extend away from the array of coupling light guides 104 toward the light emission region 108. The plurality of reflective surfaces 4801 may include linear light reflective surfaces 4915 (as shown in fig. 49), or may be linear sub-regions of light transmissive material added to surface 4809 of thin film based light guide 4805. The array of coupling lightguides 104 comprises a pitch 4806 in an array direction 9313 of the array of coupling lightguides 104, and the plurality of reflective surfaces 4801 has a pitch 4911 (as in fig. 49), wherein the pitch 4806 (or average pitch) of the array of coupling lightguides 104 is at least five times the pitch 4911 (or average pitch) of the plurality of reflective surfaces 4801. The plurality of reflective surfaces 4801 (which may be linear total internal reflection surfaces) has a length 4807 in a direction 4810 perpendicular to the array direction 9313 of the array of coupling lightguides 104 and perpendicular to the thickness direction 4913 of the light mixing region 105 (parallel to + in direction as shown in fig. 49). The reflective surface 4801 is lengthwise oriented in a direction 4810 perpendicular to the array direction 9313 of the array of coupling lightguides 104.

Fig. 49 is a cross-sectional view of the light emitting device 4800 in the y-z plane as shown in fig. 48. The plurality of reflective surfaces 4801 have a pitch 4911 (or average pitch) and a width 4912 (or average width) in a direction parallel to the array direction 9313 of the array of coupling lightguides and perpendicular to the thickness direction 4913 of the thin film based lightguide 4805 in the light mixing region 105. A length 4807 (or average length) of the plurality of reflective surfaces 4801 divided by a width 4912 (or average width) of the plurality of reflective surfaces 4801 can be greater than one hundred. The plurality of reflective surfaces 4801 have a height 4916 (or average height) in a thickness direction 4913 of the core layer 4919 in the light-mixing region 105 of the thin-film based light guide 4805. The plurality of reflective surfaces 4801 has a cross-sectional area 4917 and the thin-film based light guide includes an overall continuous cross-sectional area 4918 of core layer 4919 of thin-film based light guide 4805 directly below (or in some embodiments above) an area 4804 defined by the plurality of reflective surfaces. An overall cross-sectional area 4917 of the plurality of reflective surfaces 4801 is less than 40% of an overall continuous cross-sectional area 4918 of a core layer 4919 of the thin film-based light guide in a plane (parallel to the y-z plane) that includes a thickness direction 4913 of the thin film-based light guide and is parallel to an array direction 9313 of the array of coupling light guides that is directly below the plurality of reflective surfaces 4801. A portion 4803 of light 4802 reflected from one or more of the plurality of reflective surfaces 4801 is reflected toward lateral edge 1502 of thin film based light guide 4805. In some embodiments, the plurality of reflective surfaces 4801 can include a single curved reflective surface, such as a curved surface of stripes of light transmissive material printed on the core layer 4919 of the thin film based light guide 4805. The film-based light guide 4805 can include a cladding layer (and optionally another cladding layer below the core layer 4919) over the plurality of reflective surfaces 4801 and over the core layer 4919, such as a pressure sensitive adhesive having a refractive index less than the core layer 4919.

Fig. 50 is a cross-sectional view in a plane parallel to the array direction of the array of coupling lightguides and parallel to the thickness direction of the film, in the light mixing region of a thin-film based lightguide 5002 (e.g., similar to that shown in fig. 48) of one embodiment of a light emitting device in which a plurality of reflective surfaces 5004 are formed in printed lines 5003 of light transmissive material on a core layer 4919 of the thin-film based lightguide. In this embodiment, the film-based light guide includes an adhesive cladding layer 3806 that is located over the plurality of reflective surfaces 5004 and over the core layer 4919 (and optionally another cladding layer (not shown) below the core layer 4919), such as a pressure sensitive adhesive having a refractive index that is less than that of the core layer 4919. The plurality of reflective surfaces 5004 has a width 5005 (or an average width) in a direction parallel to an array direction 9313 of an array of coupling light guides (not shown, see fig. 48) and perpendicular to a thickness direction 4913 of the thin film-based light guide in the light mixing region.

Fig. 51 is a cross-sectional view in the light mixing region of a film-based light guide 5102 of an embodiment of a light emitting device in a plane parallel to the array of coupling light guides and parallel to the thickness direction of the film (e.g., similar to the one shown in fig. 48) in which the plurality of reflective surfaces 5101 are cutouts formed in the core layer 4919 of the film-based light guide. The film-based light guide 5202 includes an adhesive cladding layer 3806 over the plurality of reflective surfaces 5101 and over the core layer 4919 (and optionally another cladding layer below the core layer 4919), such as a pressure sensitive adhesive having a refractive index less than that of the core layer 4919.

Fig. 52 is a perspective view of one embodiment of a light emitting apparatus 5200 that includes a thin film based light guide 107, an array of multiple reflective surfaces 5201 optically coupled to the thin film based light guide 107, a reflective spatial light modulator 1559, and a light source 102. In this embodiment, the reflective spatial light modulator 1559 includes an active layer 1553 located between a bottom substrate 1554 and a top substrate 1650. The top substrate 1650 of the reflective spatial light modulator 1559 is optically coupled to the film-based light guide 107 using the adhesive cladding layer 3806. A portion of the light-mixing region 105 of the thin-film based light guide 107 (the region of the thin-film based light guide between the light-emitting region 108 and the array of coupling light guides 104 along the optical path of the light) is folded behind the light-emitting region 108 of the thin-film based light guide 107 in the thickness direction (z-direction). In one embodiment, the plurality of reflective surfaces 5201 are located at a portion of the light mixing area 105 of the thin-film based light guide 107 that does not extend behind the light emitting area 108 of the thin-film based light guide 107 in the thickness direction (the z-direction). In one embodiment, the light emitting device 5200 is a front-lit reflective display. In this embodiment, the plurality of reflective surfaces 5201 may be optically coupled to the thin film based light guide 107 by, for example, printing a linear light transmissive material on the thin film based light guide 107.

Fig. 53 is a perspective view of one embodiment of a light emitting device 5300 including a thin film-based light guide 107, an array of multiple reflective surfaces 5301 optically coupled to the thin film-based light guide 107, a reflective spatial light modulator 1559, and a light source 102. In this embodiment, the reflective spatial light modulator 1559 includes an active layer 1553 located between a bottom substrate 1554 and a top substrate 1650. The top substrate 1650 of the reflective spatial light modulator 1559 is optically coupled to the thin film based light guide 107 using the adhesive cladding layer 3806. A portion of the light-mixing region 105 of the film-based light guide 107 (the region of the film-based light guide between the light-emitting region 108 and the array of coupling light guides 104 along the optical path of the light) is folded behind the light-emitting region 108 of the film-based light guide 107 in the thickness direction (z-direction). In this embodiment, the plurality of reflective surfaces 5301 are positioned on a portion of the light mixing region 105 of the film-based light guide 107 that extends behind the light emission region 108 of the film-based light guide 107 in the thickness direction (z-direction). In some embodiments, the plurality of reflective surfaces are on both sides of the folded portion of the light mixing region 105, but do not extend behind the light emission area of the film-based light guide. In one embodiment, the light emitting device 5300 is a front lit reflective display.

In one embodiment, a light emitting device (e.g., such as a front light for a reflective display) includes a film-based light guide, where a surface of the film defines a first light guide that is optically coupled to a light redirecting optical element or other film, and where the combination of the surface of the first light guide and one or more surfaces of the light redirecting optical element or other film define a second light guide, where the second light guide may include the first light guide. In one embodiment, a reflective display includes a lightguide in which an effective thickness of the lightguide bounded by total internal reflection interfaces is increased such that total internal reflection light within the core layer is frustrated by a plurality of light extraction features such that it passes through the first cladding layer and is totally internally reflected at one of the total internal reflection interfaces of the light redirecting optical element. In another embodiment, the first light guide and the second light guide comprise the core layer, the second light guide being defined by propagation of a portion of the frustrated total internal reflection light from the first light guide by total internal reflection between a surface and an area of the first light guide, wherein light redirecting features of the light redirecting optical element occupy less than 50% of the surface of the light redirecting optical element, the area of the surface of the light redirecting element being defined between the light redirecting features and reflect a second portion of the frustrated total internal reflection light from the light extraction features back by total internal reflection to the first cladding layer and into the core layer of the first light guide where it is totally internally reflected from the surface of the first light guide and subsequently reflected by the light redirecting features towards the reflective spatial light modulator.

In one embodiment, a light emitting device includes: a thin film light guide of light guide material having a refractive index of nDL comprising a body having a first surface and an opposing second surface; a plurality of coupling lightguides extending from the body, each coupling lightguide of the plurality of coupling lightguides having an end, the plurality of coupling lightguides folded and stacked such that the ends of the plurality of coupling lightguides define a light input surface; the body of the film comprises a first core layer comprising a first material having a first refractive index nD1 and a second core layer comprising a second material having a second refractive index nD2, wherein nDL > nD2> nD1; a plurality of low angle guiding features optically coupled to the body of the light guide; a plurality of light turning features optically coupled to the light guide; wherein light propagating at the first angle within the light guide under total internal reflection is redirected by the low angle guiding features to a second angle less than a critical angle of an interface between the core light guiding layer and the second layer, a portion of the redirected light propagating through the interface and redirected by the light turning features to an angle within 30 degrees of a thickness direction of the film.

In one aspect, a light emitting device including a film having a coupling lightguide extending therefrom includes a coupling lightguide relative position retaining element (RPME) including a connected angled tooth or a ridge region of a guide array. In another aspect, the angled teeth or guides of the RPME are physically coupled by a ridge extending without extending beyond the volume defined between the overlapping portions of the array of coupling lightguides in the folded region. In another aspect, the array of angled teeth in the RPME includes a first edge oriented at a first tooth edge angle with respect to a direction of extension of the teeth (direction of extension of the teeth from the ridge, perpendicular to the array direction of the array of teeth), and a second edge oriented at a second tooth edge angle with respect to the direction of extension of the teeth, wherein the first tooth edge angle and the second tooth edge angle are greater than 0 degrees.

In another aspect, the light guide, cladding layer, or adhesive optically coupled to the light guide comprises a flexible or impact absorbing material. In another aspect, the light transmissive light guide, adhesive or component physically and/or optically coupled to the light guide has an ASTM D2240 shore a hardness of greater than or equal to 5, 10, 20, 30, 40, 50, 60, 70, and 80.

In one aspect, a light input-coupler for a light emitting device comprises a wrapper surrounding a stack of coupled light guides, wherein the wrapper comprises a film having a young's modulus less than one selected from the group consisting of: 10. 8, 6, 4, 2, 1, 0.5 and 0.1 gigapascals. In another aspect, the wrap includes perforations or aligned holes. In another aspect, the wrapper material is a conformal material that is coated or injected into a cavity or region that includes the coupling lightguides.

Exemplary embodiments of light emitting devices and methods of making or fabricating the same are described above in detail. The apparatus, components, and methods are not limited to the specific embodiments described herein, but rather, apparatus, components of apparatus, and/or steps of the methods may be utilized independently and separately from other apparatus, components, and/or steps described herein. Further, the described devices, components, and/or method steps may also be defined in or used in combination with other devices and/or methods, and are not limited to practice with only the devices and methods as described herein.

While the disclosure includes various specific embodiments, those skilled in the art will recognize that these embodiments can be practiced with modification within the spirit and scope of the disclosure and claims.

It is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

Reference throughout this specification to "one embodiment" or "an embodiment" may mean that a particular feature, structure, or characteristic described in connection with the particular embodiment may be included in at least one embodiment of claimed subject matter. Thus, the appearances of the phrase "in one embodiment" or "an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment or to any one particular embodiment described. Furthermore, it is to be understood that the particular features, structures, or characteristics described may be combined in various ways in one or more embodiments. Of course, in general, these and other issues may vary depending on the particular context of use. Thus, the particular context of description or use of these terms may provide useful guidance regarding inferences to be drawn for that context.

Equivalents of the same

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this disclosure. Various substitutions, alterations, and modifications may be made to the embodiments without departing from the spirit and scope of the disclosure. Other aspects, advantages, and modifications are within the scope of the disclosure. This disclosure is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Unless otherwise indicated, all numbers expressing feature sizes, quantities, and physical properties used in the specification and claims are to be understood as being modified by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. Unless indicated to the contrary, all tests and performance were measured at ambient temperature at 25 degrees celsius or at ambient temperature inside or near the device when turned on (when displayed) at constant ambient room temperature at 25 degrees celsius. Unless otherwise indicated, the refractive indices referred to herein are measured at the yellow bimodal sodium D line, with a wavelength of 589 nanometers. Elements in the figures are not drawn to scale.

Claims

1. A light emitting device comprising:

a. a light guide formed from a film having lateral edges and opposing surfaces and a thickness therebetween of no more than 0.5 millimeters, the light guide having an array of coupling light guides in the form of strips of the film extending from and continuous with a light guide region of the film, wherein

i) Each coupling light guide in the array of coupling light guides terminates at an edge; and is

ii) each coupling lightguide is folded in a folding region such that the array of coupling lightguides and its edges are stacked;

b. a light source positioned to emit light into the stacked edge of the array of coupling lightguides;

c. a light-emitting region within the light-guiding region of the film, the light-emitting region including a plurality of light extraction features that frustrate totally internally reflected light propagating within the film such that light exits the film in the light-emitting region; and

d. a light-mixing region of the lightguide defined between the array of coupling lightguides and the light-emitting region of the film, the light-mixing region comprising a plurality of linear reflective surfaces between the lateral edges of the film;

wherein light emitted from the light source propagates in the array of coupling lightguides by total internal reflection to the light-mixing region, mixes in the light-mixing region upon exiting the array of coupling lightguides, reflects from one or more of the plurality of linear reflective surfaces toward one or more of the lateral edges of the film, and exits the film in the light-emitting region.

2. The light emitting device of claim 1, wherein the plurality of linear reflective surfaces are parallel stripes of light transmissive material disposed on a surface of the film in the light mixing region.

3. The light emitting device of claim 2, wherein the plurality of linear reflective surfaces have an average length in a direction perpendicular to an array direction of the array of coupling lightguides and perpendicular to a thickness direction of the thin film in the light mixing region; the plurality of linear reflective surfaces have an average width in a direction parallel to an array direction of the array of coupling light guides and perpendicular to a thickness direction of the film in the light mixing region, and the average length divided by the average width is greater than 5.

4. The light emitting device of claim 1, wherein an average area of surfaces of the opposing surfaces occupied by the plurality of linear reflective surfaces, among areas of the surfaces defined by the plurality of linear reflective surfaces, is less than 40%.

5. The light emitting device of claim 1, wherein the plurality of linear reflective surfaces are positioned on a core layer of the film, a total cross-sectional area of the plurality of linear reflective surfaces in a plane that includes a thickness direction of the film and is parallel to an array direction of the array of coupling lightguides being less than 40% of a total continuous cross-sectional area of the core layer of the film directly below the plurality of linear reflective surfaces.

6. The light emitting device of claim 1, wherein the plurality of linear reflective surfaces are oriented lengthwise along a direction perpendicular to an array direction of the array of coupling light guides.

7. The light emitting device of claim 1, wherein the plurality of linear reflective surfaces reflect less than 20% of light propagating within the light guide out of the light guide in the light mixing region.

8. The light emitting device of claim 1, wherein the array of coupling light guides has an average pitch in an array direction of the array of coupling light guides and the plurality of linear reflective surfaces has an average pitch in an array direction of the array of coupling light guides, wherein the average pitch of the array of coupling light guides is at least 5 times greater than the average pitch of the plurality of linear reflective surfaces.

9. The light emitting device of claim 1, wherein the plurality of linear reflective surfaces have an average length in a direction perpendicular to the array direction of the array of coupling light guides and perpendicular to a thickness direction of the film in the light mixing region, the plurality of linear reflective surfaces have an average width in a direction parallel to the array direction of the array of coupling light guides and perpendicular to the thickness direction of the film in the light mixing region, and the average length divided by the average width is greater than 5.

10. The light emitting device of claim 1, wherein the light mixing region comprises a fold such that a portion of the light mixing region is positioned behind the light emitting region in a thickness direction of the film.

11. The light emitting apparatus of claim 10, wherein at least a portion of the plurality of linear reflective surfaces is located behind the light emitting region in a thickness direction of the thin film.

12. The light emitting apparatus of claim 1, further comprising a reflective spatial light modulator having a front-view side optically coupled to the film in the light-emitting area of the film, wherein light exiting the film in the light-emitting area illuminates the reflective spatial light modulator from the front-view side.

13. A light emitting device comprising:

a. a light guide made from a film having lateral edges and opposing surfaces and a thickness therebetween of no more than 0.5 mm, the light guide comprising an array of coupling light guides extending from and continuous with a light guide region of the film in the form of strips of the film in an array direction, wherein

c. a light emission region within the light guiding region of the film comprising a plurality of light extraction features that frustrate total internal reflection light propagating within the film such that light exits the film in the light emission region; and

d. a light-mixing region of the light guide defined between the array of coupling light guides and the light-emitting region of the film, the light-mixing region comprising a plurality of linear reflective surfaces affixed to a light-transmissive material of the film; the plurality of linear reflective surfaces extend away from the array of coupling light guides towards the light emission area,

wherein light emitted from the light source propagates within the array of coupling lightguides by total internal reflection to the light mixing region, mixes in the light mixing region upon exiting the coupling lightguides, reflects from one or more of the plurality of linear reflective surfaces toward one or more of the lateral edges of the film, and exits the film in the light emission region.

14. The light emitting device of claim 13, wherein the plurality of linear reflective surfaces are oriented such that a portion of the plurality of linear reflective surfaces have features parallel to a thickness direction of the film.

15. The light emitting device of claim 13, wherein the coupling light guide array has an average pitch and the plurality of linear reflective surfaces have an average pitch, wherein the average pitch of the coupling light guide array is at least 5 times greater than the average pitch of the plurality of linear reflective surfaces.

16. The light emitting device of claim 13, wherein the array of coupling light guides has an average width in an array direction of the array of coupling light guides and the plurality of linear reflective surfaces has an average width in the array direction, wherein the average width of the array of coupling light guides divided by the average width of the plurality of linear reflective surfaces is greater than 10.

17. The light emitting device of claim 13, wherein the plurality of linear reflective surfaces have an average length in a direction perpendicular to an array direction of the array of coupling light guides and perpendicular to a thickness direction of the film in the light mixing region, the plurality of linear reflective surfaces have an average width in a direction parallel to the array direction of the array of coupling light guides and perpendicular to the thickness direction of the film in the light mixing region, and the average length divided by the average width is greater than 5.

18. A light emitting device comprising:

d. a light-mixing region of the lightguide defined between the array of coupling lightguides and the light-emitting region of the film, the light-mixing region comprising a plurality of reflective surfaces of light-transmissive material printed on surfaces of the opposing surfaces of the film; the plurality of reflective surfaces extend away from the array of coupling lightguides toward the light emission region,

Wherein light emitted from the light source propagates within the array of coupling lightguides by total internal reflection to the light mixing region, mixes in the light mixing region upon exiting the coupling lightguides, reflects from one or more of the plurality of reflective surfaces toward one or more of the lateral edges of the film, and exits the film in the light emission region.

19. The light emitting device of claim 18, wherein the plurality of reflective surfaces have an average wetting contact angle of less than 20 degrees in a plane that includes a thickness direction of the film and is parallel to an array direction of the array of coupling light guides.

20. The light emitting device of claim 18, wherein the plurality of reflective surfaces have an average length in a direction perpendicular to an array direction of the array of coupling light guides and perpendicular to a thickness direction of the film in the light mixing region, the plurality of reflective surfaces have an average width in the direction parallel to the array direction of the array of coupling light guides and perpendicular to the thickness direction of the film in the light mixing region, and the average length divided by the average width is greater than 5.