WO2023235154A1

WO2023235154A1 - Backlights

Info

Publication number: WO2023235154A1
Application number: PCT/US2023/022642
Authority: WO
Inventors: Kirk Richard ALLEN; Xiang-Dong Mi
Original assignee: Corning Incorporated
Priority date: 2022-05-31
Filing date: 2023-05-18
Publication date: 2023-12-07
Also published as: TW202349074A; CN117148623A

Abstract

Backlights include a plurality of light sources and a plurality of patterned reflectors disposed on a first substrate. Each patterned reflector is in registration with a corresponding light source of the plurality of light sources. A first volume diffuser plate or a diffuser apparatus is positioned between the plurality of light sources and the plurality of patterned reflectors. In aspects, the first volume diffuser plate has a first diffuser thickness of about 300 micrometers or more and a plurality of scattering particles throughout a volume of the first volume diffuser plate. In aspects, the diffuser apparatus includes a first diffusive layer disposed on a first major surface of a carrier facing the plurality of light sources. The diffuser apparatus includes a second diffusive layer disposed on a second major surface of the carrier opposite the second major surface. The carrier has a carrier thickness of about 300 micrometers or more.

Description

BACKLIGHTS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S. C. § 119 of U.S. Provisional Application Serial No. 63/347171 filed on May 31, 2022, the content of which is relied upon and incorporated herein by reference in its entirety.

FIELD

[0002] The present disclosure relates generally to backlights and, more particularly, to backlights comprising a plurality of patterned reflectors and a diffuser.

BACKGROUND

[0003] Glass sheets can be used in display applications, for example, liquid crystal displays (UCDs), electrophoretic displays (EPDs), organic light-emitting diode displays (OUEDs), and plasma display panels (PDPs). It is known to provide a backlight to illuminate displays in display applications. However, backlights can have non-uniform light (e.g., hotspots from light sources), low illuminance, and/or light lost internally leading to internal heating. Consequently, there is a need for backlights that can be used to provide substantially spatially uniform light distributions with high luminance and low light loss due to internal absorption.

SUMMARY

[0004] The following presents a simplified summary of the disclosure to provide a basic understanding of some aspects described in the detailed description. Aspects of the disclosure provide a backlight comprising a first volume difiuser plate or a difiuser apparatus that can increase a luminance of light emitted from the backlight, for example, relative to a light without a first volume difiuser plate or a difiuser apparatus. For example, positioning the first volume diffuser or the diffuser apparatus between a plurality of light sources and the plurality of patterned reflectors can redirect at least a portion of light emitted from the plurality of light sources that would otherwise be incident on the patterned reflectors, which can reduce light lost (e.g., absorption) and increase the luminance of light emitted from the backlight. This effect is more noticeably as the angular emission spectrum decreases since more light would otherwise be incident on the plurality of patterned reflectors. Providing the first volume diffuser plate or the diffuser apparatus with a corresponding thickness of about 300 micrometers or more (e.g., about 500 micrometers or more, about 1 millimeter or more) can enable the first volume diffuser plate or the diffuser apparatus to be mechanically and dimensionally stable. This allows the first volume diffuser plate or the difiuser apparatus to be physically separated from a substrate that the plurality of patterned reflectors is disposed on and the plurality of light sources (and an encapsulation layer if present). Providing a physical separation between the first volume diffuser plate or the diffuser apparatus and the plurality of light sources (and an encapsulation layer if present) allows the use of materials that do not need to be thermally stable, which can reduce materials cost of the backlight. Also, providing a physically separated first volume diffuser plate or diffuser apparatus enables flexibility in the positioning of the first volume diffuser plate or the diffuser apparatus, which allows an optimal placement of the first volume diffuser plate or the diffuser apparatus for a substantially spatially uniform distribution of light. Further, providing the first volume diffuser plate or the diffuser apparatus

[0005] Providing a thickness of the first volume diffuser or the diffuser apparatus greater than about 300 micrometers (e.g., about 500 micrometers or more, about 1 millimeter or more) provide enough spacing between scattering events within the first volume diffuser or the diffuser apparatus to achieve the substantially spatially uniform distribution. For example, the diffuser apparatus can achieve a more spatially uniform light distribution than a single diffusive layer alone (e.g., disposed on the substrate that the plurality of patterned reflectors is disposed on) since the pair of diffusive layers separated by a carrier thickness provides enough spacing between scattering events in the corresponding diffusive layers to achieve the substantially spatially uniform distribution. Further, in combination with a second volume diffuser apparatus or the third diffusive layer can further help to achieve the substantially spatially uniform distribution. Also, the ability of the first volume diffuser or the diffuser apparatus to achieve a more spatially uniform distribution enables a total backlight thickness to be decreased, which decreases the overall size of the backlight.

[0006] The first volume diffuser or the diffuser apparatus can achieve a cosine-corrected bidirectional transmittance distribution function (ccBTDF(0°,0°)) in a range from about 0.12 to about 0.27 (e.g., from about 0.14 to about 0.23) and/or a cosine-corrected bidirectional reflectance distribution function (ccBRDF(15°,0°)) in a range from about 0.08 to about 0.21 (e.g., from about 0.13 to about 0.15) can provide good hiding power of the plurality of light sources (e.g., reducing hotspots) while minimizing light loss within the backlight (e.g., absorption of internally reflected light). Providing a ccBRDF with values in the above-mentioned range over an entire range of reflectance angles (e.g., from about -20° to about 20°) can further increase the hiding power of the plurality of light sources (e.g., reducing hotspots) while minimizing light loss within the backlight (e.g., absorption of internally reflected light). Further, the first volume diffuser or the diffuser apparatus can provide a low color shift as indicated by differences in the ccBTDF(0°,0°) or ccBRDF(15°,0°) at different optical wavelengths (e.g., 550 nm versus 650 nm) by providing substantially similar ccBTDF(0°,0°) or ccBRDF(15°,0°) values.

[0007] In aspects, a backlight comprises a plurality of light sources. The backlight comprises a first volume diffuser plate comprising a first major surface facing the plurality of light sources. The first volume diffuser plate comprises a second major surface opposite the first major surface. The first volume diffuser plate comprises a first diffuser thickness of about 300 micrometers or more defined therebetween. The first volume diffuser plate comprises a plurality of scattering particles throughout a volume of the first volume diffuser plate. The backlight comprises a plurality of patterned reflectors disposed on a first substrate. Each patterned reflector in registration with a corresponding light source of the plurality of light sources. The first volume diffuser plate is positioned between the plurality of light sources and the plurality of patterned reflectors.

[0008] In further aspects, the first diffuser thickness ranges from about 0.5 millimeters to about 3 millimeters.

[0009] In further aspects, the first volume diffuser plate comprises a cosine- corrected bidirectional transmittance distribution function (ccBTDF) for the light comprising an optical wavelength of 550 nanometers incident on the first major surface at an incident angle of 0° relative to a direction normal to the first major surface. The ccBTDF comprises a value of ccBTDF(0°,0°) from about 0.12 to about 0.27 for light transmitted through the second major surface at a transmission angle of 0° relative to a direction normal to the second major surface of the first volume diffuser plate.

[0010] In even further aspects, the value of ccBTDF(0°,0°) is from about 0. 14 to about 0.23. [0011] In even further aspects, a full width at half maximum value of the ccBTDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 0° is about 90° or more.

[0012] In further aspects, the first volume diffuser plate comprises a cosine- corrected bidirectional reflectance distribution function (ccBRDF) for light comprising an optical wavelength of 550 nanometers incident on the second major surface at an incident angle of 15° relative to a direction normal to the second major surface comprising a value of ccBRDF(15°,0°) from about 0.08 to about 0.21 for light reflected at a reflectance angle of 0° relative to the direction normal to the second major surface.

[0013] In even further aspects, the value of ccBRDF(15°,0°) is from about 0.13 to about 0.15.

[0014] In even further aspects, a maximum value of the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° is at a reflectance angle from about -5° to about 5° relative to the direction normal to the second major surface.

[0015] In even further aspects, the ccBRDF for the light comprises the optical wavelength of 550 nanometers at the incident angle of 15° comprises a value from about 0.08 to about 0.21 over an entire range of reflectance angles from -20° to 20° relative to the direction normal to the second major surface.

[0016] In even further aspects, another ccBRDF for the light comprises an optical wavelength of 650 nanometers incident on the second major surface at an incident angle of 15° relative to a direction normal to the second major surface comprising another value for light reflected at a reflectance angle of 0° relative to the direction normal to the second major surface. The another value is within about 0.03 of the value of the ccBRDF(15°,0°) for light comprising the optical wavelength of 550 nanometers at the incident angle of 15° for the reflectance angle of 0°.

[0017] In even further aspects, a full width at half maximum value of the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° is about 90° or more.

[0018] In further aspects, a first minimum distance between a light source of the plurality of light sources and the first major surface of the first volume diffuser plate is about 10 micrometers or more. [0019] In even further aspects, the backlight further comprises an encapsulation layer encapsulating the plurality of light sources. A second minimum distance between the encapsulation layer and the first major surface of the first volume diffuser plate is about 10 micrometers or more.

[0020] In further aspects, a third minimum distance between the second major surface of the first volume diffuser plate and the first substrate is about 10 micrometers or more.

[0021] In even further aspects, a third major surface of the first substrate faces the plurality of light sources. The plurality of patterned reflectors is attached to a fourth major surface of the first substrate opposite the third major surface.

[0022] In even further aspects, the plurality of patterned reflectors are attached to a third major surface of the first substrate facing the plurality of light sources.

[0023] In further aspects, the second major surface of the first volume diffuser plate is attached to a third major surface of the first substrate facing the plurality of light sources. The plurality of patterned reflectors are attached to a fourth major surface of the first substrate opposite the third major surface.

[0024] In even further aspects, a thickness profile of a patterned reflector of the plurality of patterned reflectors comprises a flat section and an outwardly tapered section extending outwardly from and surrounding the flat section. The flat section varies in thickness by no more than about 20 percent of an average thickness of the flat section. The flat section comprises a size in a first plane parallel to the third major surface of the first substrate equal to or greater than a size of a projection of the corresponding light source in the first plane.

[0025] In still further aspects, the average thickness of the flat section is about 90 micrometers or less.

[0026] In further aspects, the first volume diffuser plate comprises a haze of about 90% or more.

[0027] In further aspects, the first volume diffuser plate comprises an average transmittance over optical wavelengths from 400 nanometers to 700 nanometers of about 70% or more.

[0028] In further aspects, the backlight further comprises a second volume diffuser plate comprising a plurality of scattering particles throughout a volume of the second volume diffuser plate. The plurality of patterned reflectors is positioned between the first volume diffuser plate and the second volume diffuser plate, wherein a second diffuser thickness of the second volume diffuser plate is about 200 micrometers or more.

[0029] In even further aspects, a fourth minimum distance between the second volume diffuser plate and the first substrate is about 10 micrometers or more.

[0030] In even further aspects, the second volume diffuser plate is positioned between the plurality of patterned reflectors and a color converter.

[0031] In further aspects, the backlight further comprises a diffusive layer comprising a thickness of about 100 pm or less. The plurality of patterned reflectors is positioned between the first volume diffuser plate and the diffusive layer.

[0032] In even further aspects, the diffusive layer is positioned between the plurality of patterned reflectors and a color converter.

[0033] In further aspects, the backlight further comprises a reflective layer and a light substrate. The plurality of light sources and the reflective layer are disposed on a major surface of the light substrate.

[0034] In aspects, a backlight comprises a plurality of light sources. The backlight comprises a diffuser apparatus comprising a first diffusive layer disposed on a first major surface of a carrier facing the plurality of light sources. The diffuser apparatus comprises a second diffusive layer disposed on a second major surface of the carrier opposite the first major surface. The carrier comprises a carrier thickness of about 300 micrometers or more between the first major surface and the second major surface. The backlight comprises a plurality of patterned reflectors disposed on a first substrate. Each patterned reflector in registration with a corresponding light source of the plurality of light sources. The diffuser apparatus is positioned between the plurality of light sources and the plurality of patterned reflectors.

[0035] In further aspects, the carrier thickness ranges from about 0.5 millimeters to about 3 millimeters.

[0036] In further aspects, the diffuser apparatus comprises a cosine-corrected bidirectional transmittance distribution function (ccBTDF) for light comprising an optical wavelength of 550 nanometers incident on the first diffusive layer at an incident angle of 0° relative to a direction normal to the first major surface of the carrier, the ccBTDF comprising a value of ccBTDF(0°,0°) from about 0.12 to about 0.27 for light transmitted through the second diffusive layer at a transmission angle of 0° relative to a direction normal to the second major surface of the carrier. [0037] In even further aspects, the value of ccBTDF(0°,0°) is from about 0. 14 to about 0.23.

[0038] In even further aspects, a full width at half maximum value of the ccBTDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 0° is about 90° or more.

[0039] In further aspects, the diffuser apparatus comprises a cosine-corrected bidirectional reflectance distribution function (ccBRDF) for light comprising an optical wavelength of 550 nanometers incident on the second diffusive layer at an incident angle of 15° relative to a direction normal to the second major surface of the carrier comprising a value of ccBRDF(15°,0°) from about 0.08 to about 0.21 for light reflected a reflectance angle of 0° relative to the direction normal to the second major surface.

[0040] In even further aspects, the value of ccBRDF(15°,0°) is from about 0.13 to about 0.15.

[0041] In even further aspects, a maximum value of the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° is at a reflectance angle in a range from about -5° to about 5° relative to the direction normal to the second major surface.

[0042] In even further aspects, the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° comprises a value from about 0.08 to about 0.21 over an entire range of reflectance angles from -20° to 20° relative to the direction normal to the second major surface.

[0043] In even further aspects, another ccBRDF for light comprising an optical wavelength of 650 nanometers incident on the second major surface at an incident angle of 15° relative to a direction normal to the second major surface comprising another value for light reflected at a reflectance angle of 0° relative to the direction normal to the second major surface. The another value is within about 0.03 of the value of ccBRDF(15°,0°) for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° for the reflectance angle of 0°.

[0044] In even further aspects, a full width at half maximum value of the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° is about 90° or more. [0045] In further aspects, a first thickness of the first diffusive layer is about 200 micrometers or less. A second thickness of the second diffusive layer is about 200 micrometers or less.

[0046] In further aspects, a first minimum distance between a light source of the plurality of light sources and the first diffusive layer is about 10 micrometers or more.

[0047] In even further aspects, the backlight further comprises an encapsulation layer encapsulating the plurality of light sources. A second minimum distance between the encapsulation layer and the first diffusive layer is about 10 micrometers or more.

[0048] In further aspects, a third minimum distance between the second diffusive layer and the first substrate is about 10 micrometers or more.

[0049] In even further aspects, a third major surface of the first substrate faces the plurality of light sources. The plurality of patterned reflectors are attached to a fourth major surface of the first substrate opposite the third major surface.

[0050] In even further aspects, the plurality of patterned reflectors are attached to a third major surface of the first substrate facing the plurality of light sources.

[0051] In further aspects, the second diffusive layer is attached to a third major surface of the first substrate facing the plurality of light sources. The plurality of patterned reflectors are attached to a fourth major surface of the first substrate opposite the third major surface.

[0052] In further aspects, a thickness profile of a patterned reflector of the plurality of patterned reflectors comprises a flat section and an outwardly tapered section extending outwardly from and surrounding the flat section. The flat section varies in thickness by no more than about 20 percent of an average thickness of the flat section. The flat section comprises a size in a plane parallel to the third major surface of the first substrate equal to or greater than a size of a projection of a corresponding light source in the first plane.

[0053] In even further aspects, a reflector thickness of the flat section is about 90 micrometers or less.

[0054] In further aspects, the diffuser apparatus comprises a haze of about

90% or more. [0055] In further aspects, the diffuser apparatus comprises an average transmittance over optical wavelengths from 400 nanometers to 700 nanometers of about 70% or more.

[0056] In further aspects, the backlight further comprises a volume diffuser plate comprising a plurality of scattering particles throughout a volume of the volume diffuser plate. The plurality of patterned reflectors positioned between the diffuser apparatus and the volume diffuser plate. A thickness of the volume diffuser plate is about 200 micrometers or more.

[0057] In even further aspects, a fourth minimum distance between the volume diffuser plate and the first substrate is about 10 micrometers or more.

[0058] In even further aspects, the volume diffuser plate is positioned between the plurality of patterned reflectors and a color converter.

[0059] In further aspects, the backlight further comprises a third diffusive layer comprising a third thickness of about 200 micrometers or less. The plurality of patterned reflectors positioned between the diffuser apparatus and the third diffusive layer.

[0060] In even further aspects, the third diffusive layer is positioned between the plurality of patterned reflectors and a color converter.

[0061] In further aspects, further comprising a reflective layer and a light substrate, wherein the plurality of light sources and the reflective layer are disposed on a major surface of the light substrate.

[0062] Additional features and advantages of the aspects disclosed herein will be set forth in the detailed description that follows, and in part will be clear to those skilled in the art from that description or recognized by practicing the aspects described herein, including the detailed description which follows, the claims, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description present aspects intended to provide an overview or framework for understanding the nature and character of the aspects disclosed herein. The accompanying drawings are included to provide further understanding and are incorporated into and constitute a part of this specification. The drawings illustrate various aspects of the disclosure, and together with the description explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS [0063] These and other features, aspects, and advantages are better understood when the following detailed description is read with reference to the accompanying drawings, in which:

[0064] FIG. 1 schematically illustrates an exemplary embodiment of a backlight comprising a volume diffuser plate and a second volume diffuser plate in accordance with aspects of the disclosure;

[0065] FIG. 2 schematically illustrates an exemplary embodiment of a backlight comprising two volume diffuser plates in accordance with aspects of the disclosure;

[0066] FIG. 3 schematically illustrates an exemplary embodiment of a backlight comprising a volume diffuser plate attached to a carrier in accordance with aspects of the disclosure;

[0067] FIG. 4 schematically illustrates an exemplary embodiment of a backlight comprising a diffuser apparatus and volume diffuser plate in accordance with aspects of the disclosure;

[0068] FIG. 5 schematically illustrates an exemplary embodiment of a backlight comprising a diffuser apparatus in accordance with aspects of the disclosure;

[0069] FIG. 6 schematically illustrates an exemplary embodiment of a backlight comprising a diffuser apparatus and volume diffuser plate in accordance with aspects of the disclosure;

[0070] FIGS. 7-10 schematically illustrate cosine corrected Bi-Directional Reflectance Distribution Functions (ccBRDFs) for Examples A-D;

[0071] FIGS. 11-14 schematically illustrate cosine corrected Bi-Directional Transmittance Distribution Functions (ccBTDFs) for Examples A-D;

[0072] FIGS. 15-18 schematically illustrate ccBRDFs for Comparative Examples AA-DD; and

[0073] FIGS. 19-22 schematically illustrate ccBTDFs for Comparative Examples AA-DD.

[0074] Throughout the disclosure, the drawings are used to emphasize certain aspects. As such, it should not be assumed that the relative size of different regions, portions, and substrates shown in the drawings are proportional to its actual relative size, unless explicitly indicated otherwise.

DETAILED DESCRIPTION [0075] Aspects will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary aspects are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as limited to the aspects set forth herein.

[0076] The present disclosure relates to backlights comprising a volume diffuser plate or a diffuser apparatus. For example, FIGS. 1-6 illustrate backlights 101, 201, 301, 401, 501, and 601 comprising a plurality of light sources, a plurality of patterned reflectors, and either a volume diffuser plate or a diffuser apparatus positioned therebetween. Unless otherwise noted, a discussion of features of aspects of the backlight can apply equally to corresponding features of other backlights. The backlights can be used in a direct-view display. In aspects, the backlight can be used in a wide range of display applications, for example, liquid crystal displays (LCDs), electrophoretic displays (EPDs), organic light-emitting diode displays (OLEDs), plasma display panels (PDPs), or the like. Such display applications can be incorporated, for example, into mobile phones, tablets, laptops, watches, wearables, and/or touch-capable monitors or displays.

[0077] As schematically illustrated in FIGS. 1-6, the backlight 101, 201, 301, 401, 501, and 601 comprises a plurality of light sources 109 disposed on a major surface 105 of a light substrate 103. As shown, the plurality of light sources 109 comprise light sources 108a-108c that can be arranged in a row. Although not shown, the plurality of light sources can further be arranged in a two-dimensional array. The light sources 108a-108c can comprise inorganic light-emitting diodes (LEDs), organic LEDs (OLEDs), and/or lasers. As shown in FIGS. 1-4, a light source 108a-108c of the plurality of light sources 109 comprises a width 106 extending in a direction 104, which can be the direction that the plurality of light sources 109 is arranged in a row along. For example, the width 106 can be a maximum dimension of the light source 108a-108c in a direction perpendicular to a light-emitting direction 102.

[0078] In aspects, as shown in FIGS. 1-6, a reflective layer 107 can be disposed on the major surface 105 of the light substrate 103, for example, between the plurality of light sources 109 (e.g., surrounding a periphery of each light source 108a- 108c). The reflective layer 107 can comprise a metallic material (e.g., silver, aluminum, titania) or a polyester. The reflective layer 107 can comprise a reflectance of about 60% or more, about 80% or more, or about 90% or more averaged over optical wavelengths from 400 nanometers (nm) to 700 nm. Throughout the disclosure, transmittance, and haze are measured using a HAZE-GARD PLUS available from BYK Gardner. Throughout the disclosure, reflectance is measured using an IMAGING SPHERE available from Radiant Imaging, Inc. As used herein, reflectance is measured in accordance with ASTM F1252-21 at an angle of 15° relative to a direction normal to the surface of the material. The average reflectance is calculated by averaging reflectance measurements taken at whole number wavelengths from about 400 nm to about 700 nm. Providing the reflective layer can increase a luminance of the backlight, for example, by reflecting light incident on the reflective layer so that the light can propagate through the backlight towards a viewer rather than immediately being lost as heat due to absorption.

[0079] In aspects, as shown in FIGS. 2 and 4, an encapsulation layer 271 can encapsulate the plurality of light sources 109. As used herein, “encapsulate” means that a first material surrounds a structure such that, in combination with other structures, air cannot directly access the structure. For example, as shown, the encapsulation layer 271 surrounds the plurality of light sources 109 from above and laterally, which taken together with the reflective layer 107 (if present) and the light substrate 103 prevents air from directly accessing the plurality of light sources 109. As shown, a portion of the encapsulation layer 271 can be positioned between adjacent light sources 108a-108c and/or fully occupy the space between adjacent light sources 108a-108c. As shown, the encapsulation layer 271 is disposed on the light substrate 103 and/or the reflective layer 107. Although shown as monolithic, the encapsulation layer can also comprise a plurality of encapsulation layers with each light source encapsulated by a corresponding encapsulation layer. Although not shown, the encapsulation layer can comprise scattering particles dispersed throughout a volume of the encapsulation layer, although the encapsulation layer can be free of scattering particles in other aspects. The encapsulation layer 271 can comprise an optically clear polymer, for example, a silicone, a siloxane (e.g., poly(dimethyl siloxane) (PDMS)), an acrylate (e.g., poly(methyl methacrylate) (PMMA)), polystyrene (PS), polycarbonate (PC), a polyimide (PI), or copolymers thereof (e.g., a poly(methyl methacrylate-co-styrene)). As used herein, “optically transparent” or “optically clear” means an average transmittance of 70% or more in the wavelength range of 400 nm to 700 nm through a 1.0 mm thick piece of material, wherein the thickness is measured along the path length of light traveling through the piece of material. As used herein, an average transmittance of a material is measured by averaging over optical wavelengths in a range from 400 nm to 700 nm through a 1.0 mm thick piece of the material, which comprises measuring the transmittance of whole number wavelengths from about 400 nm to about 700 nm and averaging the measurements. Unless specified otherwise, “transmittance” of a material refers to the average transmittance of the material. In aspects, an “optically transparent material” or an “optically clear material” may have an average transmittance of 75% or more, 80% or more, 85% or more, or 90% or more, 92% or more, 94% or more, 96% or more in the wavelength range of 400 nm to 700 nm through a 1.0 mm thick piece of the material. Providing the encapsulation layer can form a hermetic seal around the light sources and/or protect the plurality of light sources from damage (e.g., from contact with another component, moisture, and/or oxygen), which can be important when the light source is an OLED. Alternatively, as shown in FIGS. 1, 3, and 5-6, the backlights 101, 301, 501, and 601 may not comprise an encapsulation layer (i.e., the light sources 108a-108c may not be encapsulated) such that there is an air gap between the plurality of light sources 109 and other structures (e.g., volume diffuser, diffuser apparatus discussed below) in the backlight in the light-emitting direction 102. Although not shown, supports can be provided to maintain a spacing between the plurality of light sources and other components of the backlights.

[0080] As shown in FIGS. 1-6, the backlight 101, 201, 301, 401, 501, and 601 comprises a plurality of patterned reflectors 121 disposed on a first substrate 113. In aspects, as shown in FIGS. 2 and 5, the plurality of patterned reflectors 121 is disposed on and/or contacts the third major surface 115 of the first substrate 113. In aspects, as shown in FIGS. 1, 3-4, and 6, the plurality of patterned reflectors 121 is disposed on and/or contacts the fourth major surface 117 of the first substrate 113. As shown, the third major surface 115 faces the plurality of light sources 109, and the third major surface 115 can extend along a first plane 116. As shown, the fourth major surface 117 is opposite the third major surface 115, and the fourth major surface 117 can extend along a second plane 118 that can be parallel to the first plane 116. A first substrate thickness 119 of the first substrate 113 is defined between the third major surface 115 and the fourth major surface 117 as the distance between the first plane 116 and the second plane 118. In aspects, the first substrate thickness 119 can be about 10 micrometers (pm) or more, about 25 pm or more, about 100 pm or more, about 300 pm or more, about 5 millimeters (mm) or less, about 3 mm or less, about 1 mm or less, or about 500 pm or less. In aspects, the first substrate thickness 119 can range from about 10 pm to about 5 mm, from about 25 pm to about 3 mm, from about 100 pm to about 1 mm, from about 300 pm to about 500 pm, or any range or subrange therebetween. In aspects, the first substrate can comprise an optically clear polymer (as discussed above), a glass-based material, a ceramic -based material, or combinations thereof.

[0081] As used herein, “glass” refers to an amorphous material comprising at least 30 mole percent (mol %) of silica (SiC ). Amorphous materials (e.g., glass) may be strengthened. As used herein, the term “strengthened” may refer to a material that has been chemically strengthened, for example, through ion exchange of larger ions for smaller ions in the material. However, other strengthening methods, for example, thermal tempering, or utilizing a mismatch of the coefficient of thermal expansion between portions of the sheet to create compressive stress and central tension regions, may be utilized to form strengthened sheets. Exemplary glass materials, which may be free of lithia or not, can comprise soda-lime glass, alkali aluminosilicate glass, alkali- containing borosilicate glass, alkali-containing aluminoborosilicate glass, alkali- containing phosphosilicate glass, and alkali -containing aluminophosphosilicate glass. Glass materials can comprise an alkali-containing glass or an alkali-free glass, either of which may be free of lithia or not. In aspects, the glass material can be alkali-free and/or comprise a low content of alkali metals (e.g., R2O of about 10 mol% or less, wherein R2O comprises at least one of Li2O Na2O, or IGO).

[0082] As used herein, “ceramic” refers to a crystalline phase. A ceramic sheet comprises one or more crystalline phase(s) constituting at least a combined 50 wt% of the ceramic sheet. Ceramic materials may be strengthened (e.g., chemically strengthened). In aspects, a ceramic material can be formed by heating a substrate comprising a glass material to form ceramic (e.g., crystalline) portions. In aspects, ceramic materials may comprise one or more nucleating agents that can facilitate the formation of crystalline phase(s). The ceramic materials can comprise one or more oxides, nitrides, oxynitrides, carbides, borides, and/or silicides.

[0083] As shown in FIGS. 1 and 4, the patterned reflectors 122a-122c of the plurality of patterned reflectors 121 comprise outer surfaces 123a-123c. A thickness profile with the thickness in a direction of the first substrate thickness 119 (e.g., parallel to the light-emitting direction 102) between the outer surfaces 123a-123c and the corresponding major surface (e.g., third major surface 115 or fourth major surface 117) that the patterned reflector is disposed on, and the profile taken in the direction 104. As shown, the thickness profiles of the patterned reflectors 122a-122c comprise a flat section 124a-124c and an outwardly tapered section 128a-128c extending outwardly from and surrounding the corresponding flat section 124a-124c. In aspects, an average thickness 129 of a flat section 124a, 124b, or 124c can be about 5 pm or more, about 50 pm or more, about 90 pm or more, about 100 pm or more, about 120 pm or less, about 150 pm or less, or about 110 pm or less. For example, the average thickness 129 can range from about 5 pm to about 150 pm, from about 50 pm to about 120 pm, from about 90 pm to about 110 pm, or any range or subrange therebetween. As used herein, the flat section 124a-124c comprises a continuous portion of the thickness profile, where a local thickness on the thickness profile varies by no more than about 20% of the average thickness 129 of the flat section 124a, 124b, or 124c for the entire flat section 124a, 124b, or 124c. For example, a local thickness for the entire flat section 124a-124c can vary by less than 15%, less than 10%, or less than 5% of the average thickness 129 of the flat section 124a, 124b, or 124c. As shown in FIGS. 1 and 4, a local thickness across the entire flat section 124a, 124b, or 124c can be substantially uniform with the outer surfaces 123a-123c in the flat sections 124a-124c substantially parallel to the corresponding major surface of the first substrate 113. As used herein, the “tapered section” refers to a section that smoothly (e.g., without sharp changes in thickness) transitions from the average thickness of the flat section and 0 thickness. In aspects, as shown in FIGS. 1 and 4, the outwardly tapered sections 128a-128c can comprise a substantially linear thickness profile with a flat outer surface, although the outwardly tapered section can comprise a curved surface with a curvilinear thickness profile (e.g., a local thickness decreases more near the flat section and then decreases less as a distance from the flat section increases) in other aspects. Providing the plurality patterned reflectors can reduce hotspots in a distribution of light emitted from the backlight by reflecting at least a portion of the light emitted from the corresponding light source (that the patterned reflector is in registration with).

[0084] As shown in FIGS. 1 and 4, each patterned reflector 122a-122c of the plurality of patterned reflectors 121 is in registration with a corresponding light source 108a, 108b, or 108c of the plurality of light sources 109. As used herein, a patterned reflector is in registration with a light source if at least a portion of a projection of the light source in a plane that the patterned reflector is disposed on overlaps the region occupied by the patterned reflector. For example, with reference to FIG. 1, the patterned reflector 122a is in registration with the light source 108a because at least a portion of a projection of the light source 108a in the second plane 118 that the patterned reflector 122a is disposed on overlaps the region occupied by the patterned reflector 122a. In aspects, as shown in FIGS. 1-4, a projection of each light source 108a-108c can be entirely within a region occupied by the corresponding patterned reflector 122a-122c in a plane (e.g., second plane 118) that the patterned reflectors 122a-122c are disposed on.

[0085] As shown in FIGS. 1 and 4, a size 126 of the flat section 124a of the patterned reflector 122a is a maximum dimension of the flat section 124a in the direction 104. For example, if the flat section comprises a circular cross-section taken parallel to the first plane 116 (or the second plane 118), then the size 126 is equal to the diameter of the circular cross-section. In aspects, the cross-section taken parallel to the first plane 116 (or the second plane 118) can be circular, rectangular, hexagonal, or another polygonal shape. In aspects, as shown in FIGS. 1 and 4, the size 126 of the flat section 124a in a plane parallel to the third major surface 115 and/or the fourth major surface 117 is equal to or greater than the width 106 of the corresponding light source 108a (e.g., a size of a projection of the corresponding light source 108a in the plane). In further aspects, the size 126 of the flat section 124a can be about 1.5 times or more, about 2 times or more, about or 3 times or more times the width 106 of the corresponding light source 108a. Each patterned reflector 122a-122c is configured to reflect at least a portion of the light emitted from the corresponding light source 108a, 108b, or 108c. The flat sections 124a-124c may be more reflective than the outwardly tapered sections 128a-128c, and the outwardly tapered sections 128a-128c may be more transmissive than the flat sections 124a-124c. Each substantially flat section can be large enough such that each patterned reflector can be aligned to the corresponding light source and small enough to achieve suitable luminance uniformity and color uniformity.

[0086] In aspects, as shown in FIGS. 1-3, the backlights 101, 201, and 301 comprise a first volume diffuser plate 143 comprising a plurality of scattering particles 144 disposed in a volume of the first volume diffuser plate 143. As used herein, a median particle size is measured using a scanning electron microscope (SEM) to image a cut cross-section of the volume diffuser plate. A median particle size of the plurality of scattering particles 144 can be about 1 pm or more, about 2 pm or more, about 5 pm or more, about 20 pm or less, about 15 pm or less, about 10 pm or less, about 8 pm or less, or about 4 pm or less. For example, the median particle size of the plurality of scattering particles 144 can range from about 1 pm to about 20 pm, from about 2 pm to about 15 pm, from about 5 pm to about 10 pm, from about 5 pm to about 8 pm, or any range or subrange therebetween. In further aspects, the plurality of scattering particles 144 can comprise a gas (e.g., air, nitrogen, oxygen, argon) or an evacuated space corresponding to a void internal to the first volume diffuser plate. In further aspects, the plurality of scattering particles 144 can comprise a glass-based material, a ceramic-based material, or a polymeric material comprising a different refractive index than a matrix material 146 that the plurality of particles are embedded in. The matrix material 146 can comprise a glass-based material, a ceramic-based material, or an optically transparent polymer, for example, a silicone, an acrylate (e.g., poly(methyl methacrylate) (PMMA)), polystyrene (PS), polycarbonate (PC), or a polyimide (PI). Also, the plurality of scattering particles 144 can comprise ceramic-based materials crystallized from a glass-based matrix material 146 in a ceramming (e.g., heating) process. Throughout the disclosure, a refractive index of a material is measured in accordance with ASTM E1967-19, where the first wavelength comprises 589 nm. In further aspects, an absolute value of a difference between the refractive index of the plurality of scattering particles 144 and the refractive index of the matrix material 146 can be about 0.1 or more, about 0.2 or more, about 0.25 or more, about 1 or less, about 0.5 or less, about 0.4 or less, or about 0.3 or less. For example, the absolute value of the difference between the refractive index of the plurality of scattering particles 144 and the refractive index of the matrix material 146 can range from about 0.1 to about 1, from about 0.2 to about 0.5, from about 0.25 to about 0.4, from about 0.25 to about 0.3, or any range or subrange therebetween. In even further aspects, the refractive index of the plurality of scattering particles 144 can be greater than the refractive index of the matrix material 146. Providing the plurality of scattering particles throughout the volume of the first volume diffuser can provide enough spacing between scattering events by light at scattering particles within the first volume diffuser achieve a substantially spatially uniform distribution of light.

[0087] As shown in FIGS. 1-3, a first diffuser thickness 149 of the first volume diffuser plate 143 is defined as an average distance between a first major surface 145 facing the plurality of light sources 109 and a second major surface 147 opposite the first major surface 145. The first diffuser thickness 149 can be about 300 pm or more, about 500 pm or more, about 1 mm or more, about 2 mm or more, about 5 mm or less, about 3 mm or less, about 2 mm or less, or about 1 mm or less. For example, the first diffuser thickness 149 can range from about 300 pm to about 5 mm, from about 500 pm to about 3 mm, from about 1 mm to about 2 mm, or any range or subrange therebetween. Providing the first diffuser thickness within one or more of the above-mentioned ranges can enable the first volume diffuser plate or the diffuser apparatus to be mechanically and dimensionally stable. This allows the first volume diffuser plate or the diffuser apparatus to be physically separated from a substrate that the plurality of patterned reflectors is disposed on and the plurality of light sources (and an encapsulation layer if present). Providing a physical separation between the first volume diffuser plate or the diffuser apparatus and the plurality of light sources (and an encapsulation layer if present) allows the use of materials that do not need to be thermally stable, which can reduce a materials cost of the backlight.

[0088] As shown in FIGS. 1-3, the first volume diffuser plate 143 is positioned between the plurality of light sources 109 and the plurality of patterned reflectors 121. As shown, a first minimum distance 161 is defined as a minimum distance between a light source 108a-108c of the plurality of light sources 109 and the first major surface 145 of the first volume diffuser plate 143 in the light-emitting direction 102. The first minimum distance 161 can be about 10 pm or more, about 20 pm or more, about 30 pm or more, about 500 pm or less, about 100 pm or less, or about 50 pm or less. For example, the first minimum distance 161 can range from about 10 pm to about 500 pm, from about 20 pm to about 100 pm, from about 30 pm to about 50 pm, or any range or subrange therebetween. In aspects, as shown in FIG. 2, a second minimum distance 281 can be defined between an outer surface 275 of the encapsulation layer 271 and the first major surface 145 of the first volume diffuser plate 143 in the light-emitting direction 102. When the encapsulation layer 271 is present, the second minimum distance 281 can be within one or more of the ranges discussed above for the first minimum distance 161. Providing a physically separated first volume diffuser plate or diffuser apparatus enables flexibility in the positioning of the first volume diffuser plate or the diffuser apparatus, which allows an optimal placement of the first volume diffuser plate or the diffuser apparatus for a substantially spatially uniform distribution of light. Further, providing a physically separated first volume diffuser plate or diffuser apparatus can reduce light lost within the backlight by reducing internal reflections.

[0089] In aspects, as shown in FIG. 3, the second major surface 147 of the first volume diffuser plate 143 can be attached (e.g., bonded, contacts) to the third major surface 115 of the first substrate 113, and the plurality of patterned reflectors 121 can be disposed on the fourth major surface 117 of the first substrate 113. Alternatively, in aspects, as shown in FIGS. 1-2, a third minimum distance 163 is defined as a minimum distance between the second major surface 147 and the third major surface 115 of the first substrate 113 in the light-emitting direction 102. The third minimum distance 163 can be within one or more of the ranges discussed above for the first minimum distance 161. In further aspects, as shown in FIG. 1, the plurality of patterned reflectors 121 can be disposed on the fourth major surface 117 of the first substrate 113. In further aspects, as shown in FIG. 2, the plurality of patterned reflectors 121 can be disposed on the third major surface 115 of the first substrate 113. In further aspects, as shown in FIG. 2, a sixth minimum distance 267 is defined as a minimum distance between the outer surfaces 123a-123c and the second major surface 147 of the first volume diffuser plate 143 can within one or more of the ranges discussed above for the first minimum distance 161.

[0090] In aspects, as shown in FIGS. 4-6, the backlights 401, 501, and 601 comprise a diffuser apparatus 451 comprising a first diffusive layer 473 and a second diffusive layer 483. The first diffusive layer 473 has a first thickness 479 defined as an average thickness between a first exterior surface 475 and a first contact surface 477 (e.g., in the light-emitting direction 102), and the second diffusive layer 483 has a second thickness 489 defined as an average thickness between a second exterior surface 487 and a second contact surface 485 (e.g., in the light-emitting direction 102). The first thickness 479 and/or the second thickness 489 can be about 200 pm or less, about 150 pm or less, about 120 pm or less, about 100 pm or less, about 80 pm or less, about 50 pm or less, about 1 pm or more, about 10 pm or more, or about 20 pm or more, or about 30 pm or more. For example, the first thickness 479 and/or the second thickness 489 can range from about 1 pm to about 200 pm, from about 10 pm about 150 pm, from about 20 pm to about 100 pm, from about 30 pm to about 80 pm, from about 30 pm to about 50 pm, or any range or subrange therebetween. In aspects, the first thickness 479 can be substantially equal to the second thickness 489. In aspects, the first diffusive layer 473 or the second diffusive layer 483 can be a surface diffusive layer.

[0091] As shown in FIGS. 4-6, the diffuser apparatus 451 comprises a carrier 453 with the first contact surface 477 of the first diffusive layer 473 disposed on (e.g., attached, bonded, contacting) a first major surface 455 of the carrier 453, and the first major surface 455 facing the plurality of light sources 109. As shown, the second contact surface 485 of the second diffusive layer 483 is disposed on (e.g., attached, bonded, contacts) a second major surface 457 of the carrier 453 opposite the first major surface 455. A carrier thickness 459 of the carrier 453 is defined as an average thickness between the first major surface 455 facing the plurality of light sources 109 and the second major surface 457 opposite the first major surface 455 (e.g., in the light-emitting direction 102). The carrier thickness 459 can be about 300 pm or more, about 500 pm or more, about 1 mm or more, about 2 mm or more, about 5 mm or less, about 3 mm or less, about 2 mm or less, or about 1 mm or less. For example, the carrier thickness 459 can range from about 300 pm to about 5 mm, from about 500 pm to about 3 mm, from about 1 mm to about 2 mm, or any range or subrange therebetween. Providing the diffuser apparatus with a carrier thickness within one or more of the above-mentioned ranges can achieve a more spatially uniform light distribution than a single diffusive layer alone (e.g., disposed on the substrate that the plurality of patterned reflectors is disposed on) or two diffusive layers directly contacting one another since the pair of diffusive layers separated by a carrier thickness provides enough spacing between scattering events in the corresponding diffusive layers to achieve the substantially spatially uniform distribution.

[0092] As shown in FIGS. 4-6, the carrier 453 is positioned between the plurality of light sources 109 and the plurality of patterned reflectors 121. As shown, a first minimum distance 461 is defined as a minimum distance between a light source 108a-108c of the plurality of light sources 109 and the first exterior surface 475 of the first diffusive layer 473 in the light-emitting direction 102. The first minimum distance 461 can be within one or more of the ranges discussed above for the first minimum distance 161. In aspects, as shown in FIG. 4, a second minimum distance 481 can be defined between an outer surface 275 of the encapsulation layer 271 and the first exterior surface 475 of the first diffusive layer 473 in the light-emitting direction 102. When the encapsulation layer 271 is present, the second minimum distance 481 can be within one or more of the ranges discussed above for the first minimum distance 161.

[0093] In aspects, as shown in FIG. 6, the second exterior surface 487 of the second diffusive layer 483 can be attached to the third major surface 115 of the first substrate 113 (e.g., the second exterior surface 487 of the second diffusive layer 483 can contact and/or be bonded to the third major surface 115 of the first substrate 113), and the plurality of patterned reflectors 121 can be disposed on the fourth major surface 117 of the first substrate 113. Alternatively, in aspects, as shown in FIGS. 4- 5, a third minimum distance 463 is defined as a minimum distance between the second exterior surface 487 of the second diffusive layer 483 and the third major surface 115 of the first substrate 113 in the light-emitting direction 102. The third minimum distance 463 can be within one or more of the ranges discussed above for the first minimum distance 161. In further aspects, as shown in FIG. 4, the plurality of patterned reflectors 121 can be disposed on the fourth major surface 117 of the first substrate 113. In further aspects, as shown in FIG. 5, the plurality of patterned reflectors 121 can be disposed on the third major surface 115 of the first substrate 113. In even further aspects, as shown, a sixth minimum distance 567 is defined as a minimum distance between the outer surfaces 123a-123c of the plurality of patterned reflectors 121 and a second exterior surface 487 of the second diffusive layer 483 of the diffuser apparatus 451.

[0094] The first volume diffuser plate 143 and/or the diffuser apparatus 451 can comprise an average transmittance over optical wavelengths from 400 nm to about 700 nm of about 70% or more, about 75% or more, about 80% or more, about 85% or more, or about 90% or more. The first volume diffuser plate 143 and/or the diffuser apparatus 451 can comprise a haze of about 90% or more, about 95% or more, about 98% or more, or about 99% or more. As used herein, haze refers to transmission haze that is measured through the first volume diffuser plate 143 or the diffuser apparatus 451 in accordance with ASTM D1003-21 at 0° relative to a direction normal to the first major surface 145 or 455. Haze is measured using a HAZE-GARD PLUS available from BYK Gardner with an aperture over the source port. The aperture has a diameter of 8 mm. A CIE C illuminant is used as the light source for illuminating the first volume diffuser plate 143 or the diffuser apparatus 451. [0095] Throughout the disclosure, a cosine corrected Bi-Directional Transmittance Distribution Function (ccBTDF) and a cosine corrected Bi-Directional Reflectance Distribution Function (ccBRDF) are measured using an IMAGING SPHERE available from Radiant Imaging, Inc. Unless otherwise stated, the ccBTDF and ccBRDF are measured for light comprising an optical wavelength of 550 nm. As used herein, the ccBTDF is measured by transmitting light that is incident on the first major surface (of the first volume diffuser plate 143 or the carrier 453 of the diffuser apparatus 451) at an incidence angle 0i of 0° relative to a direction normal to the first major surface, measuring the distribution of light flux as a function of a transmitted angle 0T that is measured relative to a direction normal to the second major surface, and then multiplying the distribution of light flux by COS(0T) to obtain the ccBTDF. Light flux refers to the light intensity of light (e.g., in lumens) per unit area (e.g., meters squared) at a location that the area is centered. For simplicity, the value of the ccBTDF for an incidence angle 0i and a transmitted angle 0T will be referred to as ccBTDF(0i, 0T). For example, ccBTDF(0°,0°) refers to the value of the ccBTDF for light incident on the first major surface at an incidence angle 0i of 0° relative to a direction normal to the first major surface and transmitted through the second major surface at a transmission angle 0T of 0° relative to a direction normal to the second major surface. Without wishing to be bound by theory, the Bi-Directional Transmittance Distribution Function (BTDF) is a ratio of transmitted light to incident light, and the ccBTDF(0i, 0T) = BTDF(0i, 0T) * COS(0T). Without wishing to be bound by theory, the ccBTDF may better reflect how the transmitted light is perceived by the human eye (e.g., viewer) relative to the BTDF.

[0096] The value of the ccBTDF(0°,0°) corresponds to the ratio of light that makes it to a viewer viewing the backlight in a direction normal to the first volume diffuser plate 143 and/or the diffuser apparatus 451 relative to the light incident to the first volume diffuser plate 143 and/or the diffuser apparatus 451. The first volume diffuser plate 143 and/or the diffuser apparatus 451 can comprise a value of the ccBTDF(0°,0°) of about 0.10 or more, about 0.12 or more, about 0.14 or more, about 0. 17 or more, about 0.20 or more, about 0.30 or less, about 0.27 or less, about 0.23 or less, about 0.20 or less, or about 0.17 or less. The value of the ccBTDF(0°,0°) can range from about 0.10 to about 0.30, from about 0.12 to about 0.27, from about 0.14 to about 0.23, from about 0.14 to about 0.20, from about 0.17 to about 0.20, or any range or subrange therebetween. Without wishing to be bound by theory, when a value of the ccBTDF(0°,0^o) is about 0.27 or more, the first volume diffuser plate 143 and/or the diffuser apparatus 451 can have low hiding power, which either leads to hotspots, requires a thicker diffuser, or requires additional diffusers. Without wishing to be bound by theory, when a value of the ccBTDF(0°,0°) is about 0.12 or less, the first volume diffuser plate 143 and/or the diffuser apparatus 451 can reflect additional light that can be lost to internal absorption and reducing the luminance of the backlight.

[0097] The first volume diffuser plate 143 and/or the diffuser apparatus 451 can comprises another ccBTDF for light comprising an optical wavelength of 650 nm (CCBTDF₆₅O) (rather than the ccBTDF for light at an optical wavelength of 550 nm (CCBTDF550) discussed above). In aspects, the value of the ccBTDF65o(O°,O°) can be within about 0.05, about 0.04, about 0.03, or about 0.02 of the value of the CCBTDF55O(O°,O°). AS used herein, “within X” means that a magnitude (i.e., absolute value) of the difference between the values is equal to or less than X. The first volume diffuser plate 143 and/or the diffuser apparatus 451 can comprises an additional ccBTDF for light comprising an optical wavelength of 450 nm (ccBTDF 450) (rather than the CCBTDF550 or ccBTDFeso discussed above). In aspects, the value of the CCBTDF45O(O°,O°) can be within about 0.05, about 0.04, about 0.03, or about 0.02 of the value of the ccBTDF55o(O°,O°). Providing the first volume diffuser or the diffuser apparatus can provide a low color shift as indicated by differences in the ccBTDF(0°,0°) or ccBRDF(15°,0°) at different optical wavelengths (e.g., 550 nm versus 650 nm) by providing substantially similar ccBTDF(0°,0°) or ccBRDF(15°,0°) values.

[0098] As used herein, the ccBRDF is measured by impinging light on the second major surface (of the first volume diffuser plate or the substrate of the diffuser apparatus) at an incidence angle 0i of 15° relative to a direction normal to the second major surface, measuring the distribution of light flux as a function of a reflectance angle 0R that is measured relative to a direction normal to the second major surface, and then multiplying the distribution of light flux by COS(0R) to obtain the ccBRDF. For simplicity, the value of the ccBRDF for an incidence angle 0i and a reflectance angle 0R will be referred to as ccBRDF(0i, 0T). For example, ccBRDF(15°,0°) refers to the value of the ccBTDF for light incident on the second major surface at an incidence angle 0i of 15° relative to a direction normal to the second major surface and reflected at a reflectance angle 0R of 0° relative to a direction normal to the second major surface. The Bi-Directional Reflectance Distribution Function (BRDF) is a ratio of reflected light to incident light, and the ccBRDF(0i, 0R) = BRDF(0i, 0R) * COS(0R). The ccBRDF may better reflect how the reflected light is perceived by the human eye (e.g., viewer) relative to the BRDF.

[0099] The first volume diffuser plate 143 and/or the diffuser apparatus 451 can comprise a value of the ccBRDF(15°,0°) of about 0.05 or more, about 0.08 or more, about 0.10 or more, about 0.13 or more, about 0. 14 or more, about 0.25 or less, about 0.21 or less, about 0.18 or less, or about 0.15 or less. The value of the ccBRDF(15°,0°) can range from about 0.05 to about 0.25, from about 0.08 to about 0.21, from about 0.10 to about 0.18, from about 0.13 to about 0.15, from about 0.14 to about 0.15, or any range or subrange therebetween. When a value of the ccBRDF(15°,0°) is about 0.08 or less, the first volume diffuser plate 143 and/or the diffuser apparatus 451 can have low hiding power, which either leads to hotspots or requires additional diffusers. When a value of the ccBRDF(15°,0°) is about 0.21 or more, the first volume diffuser plate 143 and/or the diffuser apparatus 451 can reflect additional light that can be lost to internal absorption and reducing the luminance of the backlight.

[00100] In aspects, the ccBRDF for light at an incident angle of 15° can be within one or more of the above-mentioned ranges for the value of ccBRDF(15°,0°) over an entire range of reflectance angles from -5° to 5°, from -10° to -10°, from -15° to -15°, or from -20° to about -20°. In aspects, a maximum value of the ccBRDF for light at the incident angle of 15° can be at a reflectance angle from about -5° to about 5°. Providing a maximum value of the ccBRDF at a reflectance angle of about 0° (e.g., from about -5° to about 5°) can increase a luminance of the backlight as perceived by a viewer viewing the backlight at a direction normal to the second major surface of the first volume diffuser plate or the diffuser apparatus.

[00101] As used herein, a full width at half maximum (FWHM) refers to a width of a curve measured at half of the maximum height of the curve. In aspects, the ccBRDF(15°, 0R) and/or ccBTDF(0°, 0T) can be about 60° or more, about 75° or more, about 90° or more, about 95° or more, about 100° or more, or about 105° or more. In aspects, the ccBRDF(15°, 0R) and/or ccBTDF(0°, 0T) can range from about 60° to about 150°, from about 75° to about 140°, from about 90° to about 130°, from about 95° to about 125°, from about 100° to about 122°, from about 105° to about 120°, or any range or subrange therebetween. [00102] The first volume diffuser plate 143 and/or the diffuser apparatus 451 can comprises another ccBRDF for light comprising an optical wavelength of 650 nm (CCBRDF₆₅O) (rather than the ccBRDF for light at an optical wavelength of 550 nm (ccBRDFsso) discussed above). In aspects, the value of the ccBRDF65o(15°,O°) can be within about 0.05, about 0.04, about 0.03, or about 0.02 of the value of the CCBRDF55O(15°,O°). The first volume diffuser plate 143 and/or the diffuser apparatus 451 can comprises an additional ccBRDF for light comprising an optical wavelength of 450 nm (CCBRDF450) (rather than the CCBRDF550 or ccBRDFeso discussed above). In aspects, the value of the ccBRDF45o(15°,O°) can be within about 0.05, about 0.04, about 0.03, or about 0.02 of the value of the ccBRDF55o(15°,O°).

[00103] As shown in FIGS. 1-2, 4, and 6, the backlights 101, 201, 401, and 601 can further comprise a second volume diffuser plate 153 comprising a plurality of scattering particles 154 disposed in a volume of the second volume diffuser plate 153. The plurality of scattering particles 154 can comprise a median particle size within one or more of the ranges discussed above for the median particle size of the plurality of scattering particles 144 in the first volume diffuser plate 143. The second volume diffuser plate 153 comprises a matrix material 156 that the plurality of particles are embedded in, and the matrix material 156 can be within one or more of the materials discussed above for the matrix material 146. A relationship between a refractive index of the plurality of scattering particles 154 and a refractive index of the matrix material 156 can be within one or more of the relationships discussed above for the first volume diffuser plate 143. A second diffuser thickness 159 of the second volume diffuser plate 153 is defined as an average distance between a fifth major surface 155 facing the plurality of light sources 109 and a sixth major surface 157 opposite the fifth major surface 155 (e.g., in the light-emitting direction 102). The second diffuser thickness 159 can be about 200 pm or more, about 300 pm or more, about 500 pm or more, about 1 mm or more, about 2 mm or more, about 5 mm or less, about 3 mm or less, about 2 mm or less, or about 1 mm or less. For example, the second diffuser thickness 159 can range from about 200 pm to about 5 mm, from about 300 pm to about 3 mm, from about 500 pm to about 3 mm, from about 1 mm to about 2 mm, or any range or subrange therebetween. As shown in FIGS. 1, 4, and 6, a fourth minimum distance 167 or 467 is defined between the fourth major surface 117 of the first substrate 113 and the fifth major surface 155 of the second volume diffuser plate 153 in the direction of the first substrate thickness 119 (e.g., parallel to the light- emitting direction 102) can be within one or more of the ranges discussed above for the first minimum distance 161. Alternatively, as shown in FIG. 2, the fifth major surface 155 of the second volume diffuser plate 153 can be attached (e.g., bonded, contacts) the fourth major surface 117 of the first substrate 113. In aspects, as shown in FIGS. 1, 4, and 6, a fifth minimum distance 165 and 465 is defined as a minimum distance between the outer surfaces 123a-123c of the plurality of patterned reflectors 121 and the fifth major surface 155 of the second volume diffuser plate 153. The fifth minimum distance 165 and 465 can be within one or more of the ranges discussed above for the first minimum distance 161. In aspects, as shown in FIGS. 1-2, the plurality of patterned reflectors 121 can be positioned between the first volume diffuser plate 143 and the second volume diffuser plate 153. In aspects, as shown in FIGS. 4 and 6, the plurality of patterned reflectors 121 can be positioned between the diffuser apparatus 451 and the second volume diffuser plate 153.

[00104] As shown in FIGS. 3 and 5, the backlights 301 and 501 can further comprise a third diffusive layer 353. In aspects, the third diffusive layer 353 can be a surface diffusive layer. A third diffusive thickness 359 is defined as an average distance between a fifth major surface 355 facing the plurality of light sources 109 and a sixth major surface 357 opposite the fifth major surface 355. The third diffusive thickness 359 can be within one or more of the ranges discussed above for the first thickness 479 and/or the second thickness 489. In aspects, as shown in FIG. 5, the third diffusive layer 353 can be attached to the first substrate 113 (e.g., the fifth major surface 355 can contact the fourth major surface 117), and the plurality of patterned reflectors 121 can be attached to the third major surface 115 of the first substrate 113. In aspects, as shown in FIG. 3, a fourth minimum distance 367 is defined between the fourth major surface 117 of the first substrate 113 and the fifth major surface 355 of the third diffusive layer 353 in the direction of the first substrate thickness 119 (e.g., parallel to the light-emitting direction 102) can be within one or more of the ranges discussed above for the first minimum distance 161. In aspects, as shown in FIG. 3, the plurality of patterned reflectors 121 can be positioned between the first volume diffuser plate 143 and the third diffusive layer 353. In aspects, as shown in FIG. 5, the plurality of patterned reflectors 121 can be positioned between the diffuser apparatus 451 and the third diffusive layer 353. In aspects, as shown in FIG. 3, a seventh minimum distance 365 is defined as a minimum distance between the outer surfaces 123a-123c of the plurality of patterned reflectors 121 and the fifth major surface 355 of the third diffusive layer 353 can be within one or more of the ranges discussed above for the first minimum distance 161.

[00105] In aspects, as shown in FIGS. 1 and 6, the backlight 101 or 601 can further comprise a display stack 130 comprising one or more of a color converter 131, a prismatic film 133, a reflective polarizer 135, and/or a display panel 137. In further aspects, as shown in FIGS. 1 and 6, the second volume diffuser plate 153 can be positioned between the color conversion layer 131 and the first substrate 113. In further aspects, although not shown, the third diffusive layer can be positioned between the color conversion layer and the first substrate.

[00106] As shown in FIGS. 1-2, 4, and 6, a total backlight distance 169, 269, 469, and 669 is defined as a minimum distance between a light source 108a-108c of the plurality of light sources 109 and the sixth major surface 157 of the second volume diffuser plate 153 in the light-emitting direction 102. As shown in FIGS. 3 and 5, a total backlight distance 369 and 569 is defined as a minimum distance between a light source 108a-108c of the plurality of light sources 109 and the sixth major surface 357 of the third diffusive layer 353 in the light-emitting direction 102. The total backlight distance 169, 269, 369, 469, 569, or 669 can be about 1 mm or more, about 2 mm or more, about 3 mm or more, about 4 mm or more, about 30 mm or less, about 20 mm or less, about 10 mm or less, or about 7 mm or less. For example, the total backlight distance 169, 269, 369, 469, 569, or 669 can range from about 1 mm to about 30 mm, from about 2 mm to about 20 mm, from about 3 mm to about 10 mm, from about 4 mm to about 7 mm, or any range or subrange therebetween. The ability of the first volume diffuser or the diffuser apparatus to achieve a more spatially uniform distribution enables a total backlight thickness to be decreased, which decreases the overall size of the backlight. It is to be understood that any of the minimum distances shown in FIGS. 1-6 can be minimized while still leaving a gap between adjacent components in order to minimize the resulting total backlight distance.

EXAMPLES

[00107] Various aspects will be further clarified by the following examples. Table 1 presents the values of ccBTDF(0°,0°), ccBRDF(15°,0°), and the reflectance angle 0R of the maximum value of CCBRDF(15°,0R) that were measured for Examples A-D and Comparative Examples AA-EE comprised using an IMAGING SPHERE available from Radiant Imaging, Inc. for light having an optical wavelength of 550 nm, as described above. Also, Table 1 presents the absolute value of the difference between ccBRDFeso (15°, 0°) and ccBRDFsso (15°, 0°) that are measured as described above. The thickness of Examples A-D and Comparative Examples AA-EE is presented in Table 1. Comparative Examples AA and BB comprised prisms on the first major surface while Comparative Examples CC-DD comprised prisms on the second major surface. Examples A-D and Comparative Example EE comprised planar major surfaces.

Table 1: Results of Examples A-D and AA-DD

[00108] As shown in Table 1, Examples A-D comprised a value of ccBTDF(0°,0°) in a range from about 0.12 to about 0.27. Examples A-C comprised a value of ccBTDF(0°,0°) in a range from about 0.14 to about 0.23. In contrast, Comparative Examples AA-EE comprised a value of ccBTDF(0°,0°) greater than 0.3, greater than 0.5, and greater than 0.6. As such, Comparative Examples AA-EE (having the high value of ccBTDF(0°,0°)) have low hiding power, which either leads to hotspots, requires a thicker diffuser, or requires additional diffusers to produce a substantially spatially uniform light distribution while Examples A-D do not have such problems. Also, Examples A-D comprise an absolute value of the difference between ccBTDF65o(O°,O°) and ccBTDF55o(O°,O°) less than about 0.03, and Examples B-C comprise an absolute value of the difference between ccBTDF65o(O°,O°) and CCBTDF55O(O°,O°) less than about 0.02. In contrast, Comparative Examples AA-DD comprise an absolute value of the difference between ccBTDF65o(O°,O°) and CCBTDF55O(O°,O°) of about 0.03 or more, and Comparative Examples CC-DD comprise an absolute value of the difference between ccBTDF65o(O°,O°) and CCBTDF55O(O°,O°) of about 0.04 or more or about 0.05 or more.

[00109] As shown in Table 1, Examples A-D comprised a value of ccBRDF(15°,0°) in a range from about 0.08 to about 0.21. Examples A-B comprised a value of ccBRDF(15°,0°) in a range from 0.13 to about 0.15 (e.g., about 0.14). In contrast, Comparative Examples AA-DD comprised a value of ccBRDF(15°,0°) greater than 0.18. Comparative Examples AA-CC comprised a value of ccBRDF(15°,0°) greater than 0.30. As such, Comparative Examples AA-CC (having the high value of ccBRDF(15°,0°)) reflect additional light that can be lost to internal absorption and reducing the luminance of the backlight compared to Examples A-D. As noted above, comparative Example DD comprises a value of ccBTDF(0°,0°) is greater than 0.3, greater than 0.5, or greater than 0.6.

[00110] As shown in Table 1, Examples A-D and Comparative Examples DD-EE comprise a maximum value of the ccBRDF for light comprising the optical wavelength of 550 nanometers at the incident angle of 15° is at a reflectance angle in a range from about -5° to about 5° (e.g., from about -2° to about 2°, about 0°). In contrast, Comparative Examples AA-CC comprise a maximum value of the ccBRDF for light comprising the optical wavelength of 550 nm at the incident angle of 15° is at a reflectance more than 10° away from 0°. Consequently, Examples A-D can provide maximum luminance directed a viewer viewing the backlight at a direction normal to the backlight. Also, Examples A-D comprise an absolute value of the difference between ccBRDF65o(15°,O°) and ccBRDF55o(15°,O°) is less than about 0.03 (e.g., less than about 0.02, less than about 0.01).

[00111] As shown in Table 1, Examples A-D comprised a FWHM of ccBTDF (0°, 0T) of about 75° or more, about 90° or more, about 95° or more, about 100° or more, or about 105° or more. In contrast, Comparative Examples AA-DD comprised a FWHM of ccBTDF(0°, 0T) of about 60° or less. As shown in Table 1, Examples A-D comprised a FWHM of ccBRDF (0°, 0R) of about 75° or more or about 90° or more, and Examples A-B and D further comprised ccBRDF (15°, 0R) of about 95° or more, about 100° or more, or about 105° or more. In contrast, Comparative Examples AA-DD comprised a FWHM of ccBRDF(15°, 0R) of about 60° or less.

[00112] In FIGS. 7-22, curves 709, 809, 909, 1009, 1109, 1209, 1309, 1409, 1509, 1609, 1709, 1809, 1909, 2009, 2109, and 2209 corresponding to incident light comprising an optical wavelength of 450 nm were smoothed to eliminate noise. FIGS. 7-10 schematically illustrate ccBRDFs for Examples A-D, respectively. In FIGS. 7-10, the horizontal axis 701 (i.e., x-axis) is the reflectance angle in degrees. The vertical axes 703, 803, 903, and 1003 (i.e., y-axis) represent the value of the ccBRDF at the corresponding reflectance angle. Curves 707, 807, 907, and 1007 correspond to ccBRDF55o(1 °, OR); curves 705, 805, 905, and 1005 correspond to ccBRDF65o(1 °, OR); and curves 709, 809, 909, and 1009 correspond to ccBRDF45o(1 °, OR). The ccBRDFs of Examples A-D comprised a unimodal distribution with a maximum value at about 0°. The curves 707, 807, and 907 corresponding to the ccBRDFs of Examples A-C shown in FIGS. 7-9 have values from about 0.08 to about 0.21 over an entire range of reflectance angles from about - 20° to 20°, from about -30° to about 30°, or from about -40° to about 40°. As shown in FIGS 7-8 and 10, the curves 705, 805, and 1005 corresponding to ccBRDF65o(1 °, OR) substantially superimpose with the curves 707, 807, and 1007 corresponding to CCBRDF₅₅₀(15^O, OR).

[00113] FIGS. 15-18 schematically illustrate ccBRDFs for Comparative Examples AA-DD, respectively. In FIGS. 15-18, the horizontal axis 1501 (i.e., x- axis) is the reflectance angle in degrees. The vertical axes 1503, 1603, 1703, and 1803 represent the value of the ccBRDF at the corresponding reflectance angle. Curves 1507, 1607, 1707, and 1807 correspond to ccBRDF55o(1 °, OR); curves 1505, 1605, 1705, and 1805 correspond to ccBRDF65o(1 °, OR); and curves 1509, 1609, 1709, and 1809 correspond to ccBRDF45o(1 °, OR). Comparative Examples AA-CC comprised bimodal distributions with local maxima at about +20° and -20°. As discussed above, Comparative Examples AA and CC comprise a value of ccBRDF(15°,0°) (see curves 1507 and 1707) less than 0.08, less than 0.06, less than 0.05, and less than 0.04. Comparative Example CC (see curve 1707) comprised a value of ccBRDF(15°,0°) greater than 0.3 with larger values in a range of reflectance angles from about -25° to about 25°. Consequently, Examples A-C increase the hiding power of the plurality of light sources (e.g., reducing hotspots) while minimizing light loss within the backlight (e.g., absorption of internally reflected light) relative to comparative Examples AA-CC.

[00114] In FIGS. 11-14, the horizontal axis 1101 (i.e., x-axis) is the transmittance angle in degrees, respectively. The vertical axes 1103, 1203, 1303, and 1403 (i.e., y-axis) represent the value of the ccBTDF at the corresponding transmittance angle. Curves 1107, 1207, 1307, and 1407 correspond to

CCBTDF₅₅O(15°, 0_T); curves 1105, 1205, 1305, and 1405 correspond to

CCBTDF65O(15°, 0T); and curves 1109, 1209, 1309, and 1409 correspond to CCBTDF45O(15°, 0T). The ccBTDFs of Examples A-D comprised a unimodal distribution with a maximum value at about 0°. Curves 1107, 1207, and 1407 corresponding to the ccBTDFs of Examples A-B and D have values from about 0.12 to about 0.25 over an entire range of reflectance angles from about -20° to 20°, from about -30° to about 30°, or from about -40° to about 40°. As shown in FIGS 12-14, the curves 1205, 1305, and 1405 corresponding to ccBTDF65o(O°, 0T) are within 0.03 or less of the curves 1207, 1307, and 1407 corresponding to ccBTDFs5o(15⁰, 0T) for the same 0T across the entire range shown.

[00115] In FIGS. 19-22, the horizontal axis 1901 (i.e., x-axis) is the transmittance angle in degrees, respectively. The vertical axis 1903 (i.e., y-axis) is the value of the ccBTDF at the corresponding transmittance angle. Curves 1907, 2007, 2107, and 2207 correspond to ccBTDF5so(1 °, 0T); curves 1905, 2005, 2105, and 2205 correspond to ccBTDF65o(1 °, 0T); and curves 1909, 2009, 2109, and 2209 correspond to ccBTDF4so(1 °, 0T). The ccBTDFs of Comparative Examples AA-DD comprised a unimodal distribution with a maximum value at about 0°. Curves 1907, 2007, 2107, and 2207 are strongly peaked with maximum values of about 0.6 or more. Consequently, Examples AA-DD have low hiding power, which either leads to hotspots, requires a thicker diffuser, or requires additional diffusers. As shown in FIGS 19-22, the curves 1905, 2005, 2105, and 2205 corresponding to ccBTDF65o(O°, 0T) substantially and the curves 1907, 2007, 2107, and 2207 corresponding to CCBTDF₅₅O(0⁰, 0T) are separated by about 0.03 or more at one or more transmittance angles, and the curves 2105 and 2205 corresponding to ccBTDFe5o(O°, 0T) and curves 2107 and 2207 are separated by about 0.05 or more at one or more transmittance angles.

[00116] Overall, Comparative Examples AA-DD (comprising a diffuser thickness of about 250 pm or less) cannot achieve the benefit of Examples A-D (comprising a diffuser thickness of about 300 pm or more, about 500 pm or more, or about 1 mm or more).

[00117] Aspects of the disclosure provide a backlight comprising a first volume diffuser plate or a diffuser apparatus that can increase a luminance of light emitted from the backlight, for example, relative to a light without a first volume diffuser plate or a diffuser apparatus. For example, positioning the first volume diffuser or the diffuser apparatus between a plurality of light sources and the plurality of patterned reflectors can redirect at least a portion of light emitted from the plurality of light sources that would otherwise be incident on the patterned reflectors, which can reduce light lost (e.g., absorption) and increase the luminance of light emitted from the backlight. This effect is more noticeably as the angular emission spectrum decreases since more light would otherwise be incident on the plurality of patterned reflectors. Providing the first volume diffuser plate or the diffuser apparatus with a corresponding thickness of about 300 micrometers or more (e.g., about 500 micrometers or more, about 1 millimeter or more) can enable the first volume diffuser plate or the diffuser apparatus to be mechanically and dimensionally stable. This allows the first volume diffuser plate or the diffuser apparatus to be physically separated from a substrate that the plurality of patterned reflectors is disposed on and the plurality of light sources (and an encapsulation layer if present). Providing a physical separation between the first volume diffuser plate or the diffuser apparatus and the plurality of light sources (and an encapsulation layer if present) allows the use of materials that do not need to be thermally stable, which can reduce materials cost of the backlight. Also, providing a physically separated first volume diffuser plate or diffuser apparatus enables flexibility in the positioning of the first volume diffuser plate or the diffuser apparatus, which allows an optimal placement of the first volume diffuser plate or the diffuser apparatus for a substantially spatially uniform distribution of light. Further, providing the first volume diffuser plate or the diffuser apparatus

[00118] Providing a thickness of the first volume diffuser or the diffuser apparatus greater than about 300 micrometers (e.g., about 500 micrometers or more, about 1 millimeter or more) provide enough spacing between scattering events within the first volume diffuser or the diffuser apparatus to achieve the substantially spatially uniform distribution. For example, the diffuser apparatus can achieve a more spatially uniform light distribution than a single diffusive layer alone (e.g., disposed on the substrate that the plurality of patterned reflectors is disposed on) since the pair of diffusive layers separated by a carrier thickness provides enough spacing between scattering events in the corresponding diffusive layers to achieve the substantially spatially uniform distribution. Further, in combination with a second volume diffuser apparatus or the third diffusive layer can further help to achieve the substantially spatially uniform distribution. Also, the ability of the first volume diffuser or the diffuser apparatus to achieve a more spatially uniform distribution enables a total backlight thickness to be decreased, which decreases the overall size of the backlight.

[00119] The first volume diffuser or the diffuser apparatus can achieve a cosine-corrected bidirectional transmittance distribution function (ccBTDF(0°,0°)) in a range from about 0.12 to about 0.27 (e.g., from about 0.14 to about 0.23) and/or a cosine-corrected bidirectional reflectance distribution function (ccBRDF(15°,0°)) in a range from about 0.08 to about 0.21 (e.g., from about 0.13 to about 0.15) can provide good hiding power of the plurality of light sources (e.g., reducing hotspots) while minimizing light loss within the backlight (e.g., absorption of internally reflected light). Providing a ccBRDF with values in the above-mentioned range over an entire range of reflectance angles (e.g., from about -20° to about 20°) can further increase the hiding power of the plurality of light sources (e.g., reducing hotspots) while minimizing light loss within the backlight (e.g., absorption of internally reflected light). Further, the first volume diffuser or the diffuser apparatus can provide a low color shift as indicated by differences in the ccBTDF(0°,0°) or ccBRDF(15°,0°) at different optical wavelengths (e.g., 550 nm versus 650 nm) by providing substantially similar ccBTDF(0°,0°) or ccBRDF(15°,0°) values.

[00120] As used herein, the terms “the,” “a,” or “an,” mean “at least one,” and should not be limited to “only one” unless explicitly indicated to the contrary. Thus, for example, reference to “a component” comprises aspects having two or more such components unless the context clearly indicates otherwise.

[00121] As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. When the term “about” is used in describing a value or an endpoint of a range, the disclosure should be understood to comprise the specific value or endpoint referred to. If a numerical value or endpoint of a range in the specification recites “about,” the numerical value or endpoint of a range is intended to comprise two aspects: one modified by “about,” and one not modified by “about.” It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint and independently of the other endpoint. [00122] The terms “substantial,” “substantially,” and variations thereof as used herein are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, as defined above, “substantially similar” is intended to denote that two values are equal or approximately equal. In aspects, “substantially similar” may denote values within about 10% of each other (e.g., within about 5% of each other, or within about 2% of each other).

[00123] As used herein, the terms “comprising” and “including,” and variations thereof, shall be construed as synonymous and open ended, unless otherwise indicated. A list of elements following the transitional phrases comprising or including is a non-exclusive list, such that elements in addition to those specifically recited in the list may also be present.

[00124] While various aspects have been described in detail with respect to certain illustrative and specific aspects thereof, the present disclosure should not be considered limited to such, as numerous modifications and combinations of the disclosed features are possible without departing from the scope of the following claims.

Claims

What is claimed is:

1. A backlight comprising : a plurality of light sources; a first volume diffuser plate comprising a first major surface facing the plurality of light sources, a second major surface opposite the first major surface, and a first diffuser thickness of about 300 micrometers or more defined therebetween, the first volume diffuser plate comprising a plurality of scattering particles throughout a volume of the first volume diffuser plate; a plurality of patterned reflectors disposed on a first substrate, each patterned reflector in registration with a corresponding light source of the plurality of light sources; and wherein the first volume diffuser plate is positioned between the plurality of light sources and the plurality of patterned reflectors.

2. The backlight of claim 1, wherein the first diffuser thickness ranges from about 0.5 millimeters to about 3 millimeters.

3. The backlight of any one of claims 1-2, wherein the first volume diffuser plate comprises a cosine-corrected bidirectional transmittance distribution function (ccBTDF) for light comprising an optical wavelength of 550 nanometers incident on the first major surface at an incident angle of 0° relative to a direction normal to the first major surface, the ccBTDF comprising a value of ccBTDF(0°,0°) from about 0.12 to about 0.27 for light transmitted through the second major surface at a transmission angle of 0° relative to a direction normal to the second major surface of the first volume diffuser plate.

4. The backlight of claim 3, wherein the value of ccBTDF(0°,0°) is from about 0.14 to about 0.23.

5. The backlight of any one of claims 3-4, wherein a full width at half maximum value of the ccBTDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 0° is about 90° or more.

6. The backlight of any one of claims 1-2, wherein the first volume diffuser plate comprises a cosine-corrected bidirectional reflectance distribution function (ccBRDF) for light comprising an optical wavelength of 550 nanometers incident on the second major surface at an incident angle of 15° relative to a direction normal to the second major surface comprising a value of ccBRDF(15°,0°) from about 0.08 to about 0.21 for light reflected at a reflectance angle of 0° relative to the direction normal to the second major surface.

7. The backlight of claim 6, wherein the value of ccBRDF(15°,0°) is from about 0.13 to about 0.15.

8. The backlight of any one of claims 6-7, wherein a maximum value of the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° is at a reflectance angle from about -5° to about 5° relative to the direction normal to the second major surface.

9. The backlight of any one of claims 6-8, wherein the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° comprises a value from about 0.08 to about 0.21 over an entire range of reflectance angles from -20° to 20° relative to the direction normal to the second major surface.

10. The backlight of any one of claims 6-9, wherein another ccBRDF for light comprising an optical wavelength of 650 nanometers incident on the second major surface at an incident angle of 15° relative to a direction normal to the second major surface comprising another value for light reflected at a reflectance angle of 0° relative to the direction normal to the second major surface, and the another value is within about 0.03 of the value of the ccBRDF(15°,0°) for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° for the reflectance angle of 0°.

11. The backlight of any one of claims 6-10, wherein a full width at half maximum value of the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° is about 90° or more.

12. The backlight of any one of claims 1-11, wherein a first minimum distance between a light source of the plurality of light sources and the first major surface of the first volume diffuser plate is about 10 micrometers or more.

13. The backlight of claim 12, further comprising an encapsulation layer encapsulating the plurality of light sources, and a second minimum distance between the encapsulation layer and the first major surface of the first volume diffuser plate is about 10 micrometers or more.

14. The backlight of any one of claims 1-13, wherein a third minimum distance between the second major surface of the first volume diffuser plate and the first substrate is about 10 micrometers or more.

15. The backlight of claim 14, wherein a third major surface of the first substrate faces the plurality of light sources, and the plurality of patterned reflectors are attached to a fourth major surface of the first substrate opposite the third major surface.

16. The backlight of claim 14, wherein the plurality of patterned reflectors are attached to a third major surface of the first substrate facing the plurality of light sources.

17. The backlight of any one of claims 1-13, wherein the second major surface of the first volume diffuser plate is attached to a third major surface of the first substrate facing the plurality of light sources, and the plurality of patterned reflectors are attached to a fourth major surface of the first substrate opposite the third major surface.

18. The backlight of any one of claims 15-17, wherein a thickness profile of a patterned reflector of the plurality of patterned reflectors comprises a flat section and an outwardly tapered section extending outwardly from and surrounding the flat section, the flat section varying in thickness by no more than about 20 percent of an average thickness of the flat section, and the flat section comprising a size in a first plane parallel to the third major surface of the first substrate equal to or greater than a size of a projection of the corresponding light source in the first plane.

19. The backlight of claim 18, wherein the average thickness of the flat section is about 90 micrometers or less.

20. The backlight of any one of claims 1-19, wherein the first volume diffuser plate comprises a haze of about 90% or more.

21. The backlight of any one of claims 1-20, wherein the first volume diffuser plate comprises an average transmittance over optical wavelengths from 400 nanometers to 700 nanometers of about 70% or more.

22. The backlight of any one of claims 1-21, further comprising a second volume diffuser plate comprising a plurality of scattering particles throughout a volume of the second volume diffuser plate, the plurality of patterned reflectors positioned between the first volume diffuser plate and the second volume diffuser plate, and a second diffuser thickness of the second volume diffuser plate is about 200 micrometers or more.

23. The backlight of claim 22, wherein a fourth minimum distance between the second volume diffuser plate and the first substrate is about 10 micrometers or more.

24. The backlight of any one of claims 22-23, wherein the second volume diffuser plate is positioned between the plurality of patterned reflectors and a color converter.

25. The backlight of any one of claims 1-21, further comprising a diffusive layer comprising a thickness of about 100 pm or less, the plurality of patterned reflectors positioned between the first volume diffuser plate and the diffusive layer.

26. The backlight of claim 25, wherein the diffusive layer is positioned between the plurality of patterned reflectors and a color converter.

27. The backlight of any one of claims 1-26, further comprising a reflective layer and a light substrate, and the plurality of light sources and the reflective layer are disposed on a major surface of the light substrate.

28. A backlight comprising: a plurality of light sources; a diffuser apparatus comprising: a first diffusive layer disposed on a first major surface of a carrier facing the plurality of light sources; and a second diffusive layer disposed on a second major surface of the carrier opposite the first major surface, the carrier comprising a carrier thickness of about 300 micrometers or more between the first major surface and the second major surface; and a plurality of patterned reflectors disposed on a first substrate, each patterned reflector in registration with a corresponding light source of the plurality of light sources, and the diffuser apparatus positioned between the plurality of light sources and the plurality of patterned reflectors.

29. The backlight of claim 28, wherein the carrier thickness ranges from about 0.5 millimeters to about 3 millimeters.

30. The backlight of any one of claims 28-29, wherein the diffuser apparatus comprises a cosine-corrected bidirectional transmittance distribution function (ccBTDF) for light comprising an optical wavelength of 550 nanometers incident on the first diffusive layer at an incident angle of 0° relative to a direction normal to the first major surface of the carrier, the ccBTDF comprising a value of ccBTDF(0°,0°) from about 0.12 to about 0.27 for light transmitted through the second diffusive layer at a transmission angle of 0° relative to a direction normal to the second major surface of the carrier.

31. The backlight of claim 30, wherein the value of ccBTDF(0°,0°) is from about 0.14 to about 0.23.

32. The backlight of any one of claims 30-31, wherein a full width at half maximum value of the ccBTDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 0° is about 90° or more.

33. The backlight of any one of claims 28-29, wherein the diffuser apparatus comprises a cosine-corrected bidirectional reflectance distribution function (ccBRDF) for light comprising an optical wavelength of 550 nanometers incident on the second diffusive layer at an incident angle of 15° relative to a direction normal to the second major surface of the carrier comprising a value of ccBRDF(15°,0°) from about 0.08 to about 0.21 for the light reflected a reflectance angle of 0° relative to the direction normal to the second major surface.

34. The backlight of claim 33, wherein the value of ccBRDF(15°,0°) is from about 0.13 to about 0.15.

35. The backlight of any one of claims 33-34, wherein a maximum value of the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° is at a reflectance angle in a range from about -5° to about 5° relative to the direction normal to the second major surface.

36. The backlight of any one of claims 33-35, wherein the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° comprises a value from about 0.08 to about 0.21 over an entire range of reflectance angles from -20° to 20° relative to the direction normal to the second major surface.

37. The backlight of any one of claims 33-36, wherein another ccBRDF for light comprising an optical wavelength of 650 nanometers incident on the second major surface at an incident angle of 15° relative to a direction normal to the second major surface comprising another value for light reflected at a reflectance angle of 0° relative to the direction normal to the second major surface, and the another value is within about 0.03 of the value of ccBRDF(15°,0°) for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° for the reflectance angle of 0°.

38. The backlight of any one of claims 33-37, wherein a full width at half maximum value of the ccBRDF for the light comprising the optical wavelength of 550 nanometers at the incident angle of 15° is about 90° or more.

39. The backlight of any one of claims 29-38, wherein a first thickness of the first diffusive layer is about 200 micrometers or less, and a second thickness of the second diffusive layer is about 200 micrometers or less.

40. The backlight of any one of claims 29-39, wherein a first minimum distance between a light source of the plurality of light sources and the first diffusive layer is about 10 micrometers or more.

41. The backlight of claim 40, further comprising an encapsulation layer encapsulating the plurality of light sources, and a second minimum distance between the encapsulation layer and the first diffusive layer is about 10 micrometers or more.

42. The backlight of any one of claims 29-41, wherein a third minimum distance between the second diffusive layer and the first substrate is about 10 micrometers or more.

43. The backlight of claim 42, wherein a third major surface of the first substrate faces the plurality of light sources, and the plurality of patterned reflectors are attached to a fourth major surface of the first substrate opposite the third major surface.

44. The backlight of claim 42, wherein the plurality of patterned reflectors are attached to a third major surface of the first substrate facing the plurality of light sources.

45. The backlight of any one of claims 29-41, wherein the second diffusive layer is attached to a third major surface of the first substrate facing the plurality of light sources, and the plurality of patterned reflectors are attached to a fourth major surface of the first substrate opposite the third major surface.

46. The backlight of any one of claims 29-45, wherein a thickness profile of a patterned reflector of the plurality of patterned reflectors comprises a flat section and an outwardly tapered section extending outwardly from and surrounding the flat section, the flat section varying in thickness by no more than about 20 percent of an average thickness of the flat section, and the flat section comprising a size in a plane parallel to the third major surface of the first substrate equal to or greater than a size of a projection of a corresponding light source in the first plane.

47. The backlight of claim 46, wherein a reflector thickness of the flat section is about 90 micrometers or less.

48. The backlight of any one of claims 29-47, wherein the diffuser apparatus comprises a haze of about 90% or more.

49. The backlight of any one of claims 29-48, wherein the diffuser apparatus comprises an average transmittance over optical wavelengths from 400 nanometers to 700 nanometers of about 70% or more.

50. The backlight of any one of claims 29-49, further comprising a volume diffuser plate comprising a plurality of scattering particles throughout a volume of the volume diffuser plate, the plurality of patterned reflectors positioned between the diffuser apparatus and the volume diffuser plate, and a thickness of the volume diffuser plate is about 200 micrometers or more.

51. The backlight of claim 50, wherein a fourth minimum distance between the volume diffuser plate and the first substrate is about 10 micrometers or more.

52. The backlight of any one of claims 50-51, wherein the volume diffuser plate is positioned between the plurality of patterned reflectors and a color converter.

53. The backlight of any one of claims 50-52, further comprising a third diffusive layer comprising a third thickness of about 200 micrometers or less, the plurality of patterned reflectors positioned between the diffuser apparatus and the third diffusive layer.

54. The backlight of claim 53, wherein the third diffusive layer is positioned between the plurality of patterned reflectors and a color converter.

55. The backlight of any one of claims 29-54, further comprising a reflective layer and a light substrate, and the plurality of light sources and the reflective layer are disposed on a major surface of the light substrate.