WO2019040688A1

WO2019040688A1 - Systems and methods for high dynamic range microled backlighting

Info

Publication number: WO2019040688A1
Application number: PCT/US2018/047637
Authority: WO
Inventors: Dana Craig Bookbinder; Dmitri Vladislavovich Kuksenkov; Timothy James Orsley; Mark Alejandro Quesada
Original assignee: Corning Incorporated
Priority date: 2017-08-24
Filing date: 2018-08-23
Publication date: 2019-02-28
Also published as: JP2020531904A; TWI799442B; CN111247369A; TW201921007A; KR20200035316A; JP7370319B2

Abstract

Embodiments are related to systems and methods for lighting, and more particularly to systems and methods for providing light for a display.

Description

SYSTEMS AND METHODS FOR HIGH DYNAMIC RANGE

MICROLED BACKLIGHTING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 1 19 of U.S.

Provisional Application Serial No. 62/689980 filed on June 26, 2018 and U.S. Provisional Application Serial No. 62/549531 filed on August 24, 2017, the contents of each of which are relied upon and incorporated herein by reference in their entireties.

FIELD

[0002] Embodiments are related to systems and methods for lighting, and more particularly to systems and methods for providing light for a display.

BACKGROUND

[0003] In some cases, backlights are constructed using a quantum dot enhancement film (QDEF) positioned between a printed circuit board (PCB) with an array of blue light emitting diodes (LEDs) and a liquid crystal display (LCD) panel. Substantial space between the LED array and QDEF is required for expansion of light emitted from the LEDs. The required space limits how thin a display can be made.

[0004] Hence, for at least the aforementioned reasons, there exists a need in the art for advanced systems and methods for lighting a display.

SUMMARY

[0005] Embodiments are related to systems and methods for lighting, and more particularly to systems and methods for providing light for a display.

[0006] This summary provides only a general outline of some embodiments of the invention. The phrases "in one embodiment," "according to one embodiment," "in various embodiments", "in one or more embodiments", "in particular embodiments" and the like generally mean the particular feature, structure, or characteristic following the phrase is included in at least one embodiment, and may be included in more than one embodiment. Importantly, such phrases do not necessarily refer to the same embodiment. Many other embodiments of the invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

[0007] A further understanding of the various embodiments may be realized by reference to the figures which are described in remaining portions of the specification. In the figures, like reference numerals are used throughout several figures to refer to similar components. In some instances, a sub-label consisting of a lower case letter is associated with a reference numeral to denote one of multiple similar components. When reference is made to a reference numeral without specification to an existing sub-label, it is intended to refer to all such multiple similar components.

[0008] Fig. l a shows a microLED backlight including zone dividers in accordance with some embodiments;

[0009] Figs, lb-li show various processing steps that may be used either separately or in combination to manufacture a backlight in accordance with some embodiments;

[0010] Fig. lj shows a display including the backlight of Fig. 1 a;

[0011] Fig. 2a shows another microLED backlight formed without substrate region dividers in accordance with various embodiments;

[0012] Fig. 2b shows a display including the backlight of Fig. 2a;

[0013] Fig. 3a shows yet another microLED backlight using blue microLEDs, red and green quantum dots, and a volume diffuser in accordance with various embodiments;

[0014] Fig. 3b shows a display including the backlight of Fig. 3a;

[0015] Fig. 4a shows yet another microLED backlight using quantum dot enhancement film (QDEF) in accordance with one or more embodiments;

[0016] Fig. 4b shows a display including the backlight of Fig. 4a;

[0017] Fig. 5a shows yet another microLED backlight using phosphor converted white microLEDs in accordance with some embodiments;

[0018] Fig. 5b shows a display including the backlight of Fig. 5a; [0019] Fig. 6a shows yet another microLED backlight using Red/Green/Blue (RGB) microLEDs in accordance with various other embodiments;

[0020] Fig. 6b shows a display including the backlight of Fig. 6a;

[0021] Fig. 7a shows yet another microLED backlight using bottom firing RGB microLEDs in accordance with one or more embodiments;

[0022] Fig. 7b shows a display including the backlight of Fig. 7a;

[0023] Fig. 8a shows yet another microLED backlight using bottom firing blue microLEDs in accordance with some other embodiments;

[0024] Fig. 8b shows a display including the backlight of Fig. 8a;

[0025] Fig. 9 is a flow diagram showing a method for making a backlit display in accordance with various embodiments;

[0026] Fig. 10 is a flow diagram showing another method for making a backlit display in accordance with some embodiments; and

[0027] Fig. 11 shows a conventional backlit display alongside a reflective backlit display in accordance with some embodiments to demonstrate the reduction in display thickness that can be achieved using embodiments.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0028] Embodiments are related to systems and methods for lighting, and more particularly to systems and methods for providing light for a display.

[0029] Various embodiments provide LCD displays that include an LCD panel and a microLED backlight in a fixed position relative to the LCD panel. The microLED backlight includes: a reflective formation; a transparent substrate; and at least one microLED device. The microLED device is disposed in relation to the reflective formation and the transparent substrate such that light emitted from the at least one microLED device both reflects off the reflective formation and passes through the transparent substrate before reaching the LCD panel. In some cases, a heat sink is bonded to the reflective formation.

[0030] In some instances of the aforementioned embodiments, the reflective formation may be, but is not limited to: (a) a quantum dot layer formed over another substrate, and a metal layer formed over the quantum dot layer; (b) a quantum dot enhancement film; (c) a quantum dot enhancement film with a metal layer formed over one surface of the quantum dot enhancement film; (d) a metal layer; (e) a diffuse reflector disposed over a surface of the substrate; or (f) a quantum dot layer formed over a surface of the substrate, and a metal layer formed over the quantum dot layer.

[0031] In one or more instances of the aforementioned embodiments, the transparent substrate is formed of glass. In some other instances of the aforementioned embodiments, the transparent substrate is formed of translucent alumina. In particular instances of the aforementioned embodiments, the microLED is a white LED. In some such instances, the reflective formation is, but it not limited to : (a) a metal layer; or (b) a diffuse reflector disposed over a surface of the substrate. In other particular instances, the microLED is a blue LED. In some such instances, the reflective formation is, but it not limited to: (a) a quantum dot layer formed over another substrate, and a metal layer formed over the quantum dot layer; (b) a quantum dot enhancement film; (c) a quantum dot enhancement film with a metal layer formed over one surface of the quantum dot enhancement film; or (d) a quantum dot layer formed over a surface of the substrate, and a metal layer formed over the quantum dot layer. In yet other particular instances, the microLEDs include a red LED, a green LED, and a blue LED. In some such instances, the reflective formation is, but it not limited to: (a) a metal layer; and (b) a diffuse reflector disposed over a surface of the first substrate.

[0032] Other embodiments provide backlight devices that include a transparent substrate, a reflective formation, and at least one microLED. The reflective formation is formed on a first side of the transparent substrate, and the microLED is disposed over a second side of the transparent substrate. The microLED is oriented such that light emitted therefrom passes through the transparent substrate and is reflected off the reflective formation to yield reflected light. The reflected light passes through the transparent substrate before being provided as a light output from the backlight device. In some cases, the reflective formation includes a metal layer to which a heat sink is bonded.

[0033] In some instances of the aforementioned embodiments where the microLED includes a blue LED, the reflective formation includes: a quantum dot layer operable to color convert blue light emitted from the blue LED to reflect red, green and blue component light. In some such instances, the quantum dot layer is disposed on the transparent substrate, and the quantum dot layer is sealed by a metal layer. In other instances of the aforementioned embodiments where the micro LED includes a blue LED, the reflective formation includes a QDEF.

[0034] In various instances of the aforementioned embodiments where the at least one microLED includes a red LED, a green LED and a blue LED, the reflective formation includes: a diffuse reflector disposed on the transparent substrate, or metal layer disposed on the transparent substrate. In some instances of the aforementioned embodiments, the transparent substrate is made of translucent alumina. In other instances of the aforementioned embodiments, the transparent substrate is made of glass.

[0035] Yet other embodiments provide backlights that include: a lighting formation and a reflective formation. The lighting formation includes: a transparent substrate; and at least one microLED disposed on a surface of the transparent substrate. The microLED is oriented such that light emitted therefrom is directed away from the transparent substrate. The reflective formation includes a reflective layer. The reflective formation is positioned in relation to the lighting formation such that light emitted from the at least one microLED reflects off the reflective layer as reflected light, and the reflected light passes through the transparent substrate as a light output from the backlight device. In some cases the reflective formation includes a metal layer to which a heat sink is bonded.

[0036] In some instances of the aforementioned embodiments, the transparent substrate is translucent alumina. In other instances of the aforementioned embodiments, the transparent substrate is glass. In various instances of the aforementioned embodiments, the surface of the transparent substrate on which the microLED is disposed is a first surface of the transparent substrate, and the lighting formation further includes a glass volume diffuser formed on a second surface of the transparent substrate. In some instances of the aforementioned embodiments, the microLED is a blue LED. In some such instances, the reflective layer includes: a quantum dot enhancement film operable to color convert blue light emitted from the blue LED to reflect red, green and blue component light; and a metal layer deposited on the quantum dot enhancement film.

[0037] In various instances of the aforementioned embodiments the transparent substrate is a first transparent substrate, and the reflective formation includes the reflective layer disposed on a second transparent substrate, where light emitted from the at least one microLED passes through the second substrate before being reflected off the reflective layer. In some such instances where the microLED is a blue LED, the reflective layer includes a quantum dot layer formed on the second transparent substrate, and a metal layer formed over the quantum dot layer. In some cases, a zone divider is formed in the second transparent substrate. The zone divider exhibits a tapered wall extending at least part way between a first surface of the second transparent substrate and a second surface of the second transparent substrate. In some particular cases, the tapered sidewall of the second transparent substrate is covered with a metal layer. In other particular cases, the tapered sidewall of the second transparent substrate is covered with both a quantum dot layer and a metal layer.

[0038] Turning to Fig. l a, microLED backlight 100 including zone dividers 140 (140a, 140b) between various zones is shown in accordance with some embodiments. MicroLED backlight 100 includes a lighting formation 121 and a reflective formation 136.

[0039] Lighting formation 121 includes a scattering surface 105 disposed over a transparent layer 110. In some embodiments, transparent layer 110 is formed of translucent alumina. Such translucent alumina acts as a circuit board connecting blue microLEDs 115 (represented as 115a, 115b, 115c) to their respective electronic power and/or control. Translucent alumina also provides a relatively high thermal conductivity (on the order of approximately 40W/m-k compared to approximately 1 W/m-k for glass). Using a material with such high thermal conductivity provides a mechanism for dissipating heat generated by blue microLEDs 115 laterally toward the edges of lighting formation 121 where a heat sink (not shown) can be mounted outside the viewing aperture. Further, the translucence of the translucent alumina helps achieve greater uniformity in RGB light reflected back by reflective formation 136 by acting as a bulk diffuser. Scattering surface 105 further enhances the diffusion caused by transparent layer 110, and as such scattering surface 105 may be any structuring or patterning of the surface of transparent layer 110 and/or material formed on the surface of transparent layer 110.

[0040] Blue microLEDs 115 (i.e., 1 15a, 115b, 115c) are connected to transparent layer 110 using conductive traces (not shown). In some cases, the conductive traces are metal traces to which blue microLEDs 115 are soldered. In various cases, the conductive traces are not straight, but rather can be zig-zag or herringbone pattern so as to reduce artefacts and undesirable Moire pattern. Blue microLEDs 115 may be any type of blue light emitting diode known in the art. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of blue light emitting diodes that may be used in relation to different embodiments. Blue microLEDs 115 are mounted such that the light they emit in operation is directed away from transparent layer 110. In some embodiments, blue microLEDs 115 are lateral devices where contacts to both the p-type material and the n-type material are located on the same side of the respective LED device. In other embodiments, blue microLEDs 115 are vertical devices where a contact to the p-type material is on one side of the device and the contact to the n-type material is on the other side of the device. For the purposes of this discussion, the aforementioned vertical devices are used.

[0041] Where such vertical devices are used the sidewalk of the respective microLEDs 115 are left open to allow for a contact with both the top and the bottom of the respective device to be formed. To avoid shorting between respective ones of blue microLEDs 115, a planarazation layer 120 is formed between respective blue microLEDs 115 such that it encapsulates the sides of blue microLEDs 115 while leaving the a top region of each of blue microLEDs 115 exposed. Planarization layer 120 is formed of any non-conductive, transparent material suitable for forming a layer that surrounds blue microLEDs 115. In some embodiments, planarization layer 120 is formed of a polymer. A transparent conductive layer 125 is formed over planarization layer 120 such that an electrically conductive connection is made between transparent conductive layer 125 and each of blue microLEDs 115. As such, assuming blue microLEDs 115 are the aforementioned vertical devices, and electrical contact is formed using transparent layer 110 to one side of each of blue microLEDs 115 and electrical contact is formed using transparent conductive layer 125 to the other side of each of blue microLEDs 115. Transparent conductive layer 125 may be made of any material that is both substantially transparent and electrically conductive. In some embodiments, transparent conductive layer 125 is formed of indium tin oxide (1TO).

[0042] Reflective formation 136 includes a reflective layer 151 that is disposed over a base substrate 135. Reflective layer 151 includes a quantum dot layer 150 disposed over base substrate 135, and a metal layer 155 disposed over quantum dot layer 150. Quantum dot layer 150 includes a number of quantum dots that operate to reflect light emitted from blue microLEDs 115. In some cases, the size and shape of the quantum dots in quantum dot layer 150 are designed such that the respective quantum dots emit light in defined frequency ranges when rays of blue light from blue microLEDs 1 15 strike the respective quantum dots. In some embodiments when the rays of blue light from blue micro LEDs 115 strike the quantum dots of quantum dot layer 150, isotropic re-emission in red or green light occurs.

[0043] Various approaches to fabricating the color conversion element identified as quantum dot layer 150 can be used, and thus quantum dot layer 150 may exhibit different compositions in different embodiments. As one example, a number of quantum dots may be mixed in a polymer suspension across a large sheet (e.g., by spray deposition, or slot die coating). Then base substrate 135 is cut or singulated into pieces matching the size of a dimming zone of reflective formation 136. Such a dimming zone may be, for example, a 50x60mm area in the case of a 65 inch display with 384 zones. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a number of dimming zone sizes that may be used in relation to different embodiments.

[0044] As shown in this embodiment, cutting base substrate includes chamfering the glass of base substrate 135 a truncated pyramids are achieved that when attached to lighting formation 121 results in triangle shaped zone dividers 140 between respective portions of base substrate 135. As the blue rays from blue microLEDs strike the quantum dots of quantum dot layer 150, the resulting re-emission is isotropic, however, the reflector redirects light in the desired direction toward the LCD panel. This means that all of the light is able to escape directly back through lighting formation 121. To avoid significant light leakage into adjacent zones which would result in undesirable cross-talk, base substrate 135 is formed in the aforementioned truncated pyramids with intervening zone dividers 140. When the re- emitted light travelling at a steep angle nearly in parallel to the converter encounters the angled sidewalls of the truncated pyramids that light is directed back toward lighting formation 121 rather than travelling on to an adjacent zone. Since some light leakage between adjacent zones may be desirable, light can be guided when passing through transparent layer 110 into adjacent zones but its scattering surface 105 promotes extraction before too much of transparent layer 110 is traversed.

[0045] In the depicted case, base substrate 135 is cut after quantum dot layer 150 is formed thereon. In other cases (not shown), base substrate 135 is cut prior to forming quantum dot layer 150 thereon. Such a pre-cutting provides an opportunity to extend quantum dot layer 150 onto sidewalls of base substrate exposed by the cutting process (i.e., quantum dot layer 150 separates base substrate 135 from intervening zone dividers 140). Having quantum dot layer 150 extended to the cut sidewalls of base layer 135 may be desirable where substantial blue light emission from blue micro LEDs 115 is expected to impinge on the sidewalls of base substrate 135.

[0046] Metal layer 155 acts both as a reflective layer and to seal the quantum dots of quantum dot layer 150. Metal layer 155 is formed after base substrate 135 is cut, and thus metal layer 155 extends to cover the cut sidewalls of base substrate 135. Where base substrate 135 was cut after the formation of quantum dot layer 150, metal layer 155 will be disposed directly on the sidewalls of base substrate 135. Alternatively, where base substrate 135 was cut before the formation of quantum dot layer 150, metal layer 155 will be disposed over quantum dot layer extended over the sidewalls of base substrate 135. Metal layer 155 may be formed of any metal that is both reflective and capable of transferring heat. In one particular embodiment, metal later 155 is a sputtered aluminum layer. Because the quantum dots of quantum dot layer 150 are used in reflection and blue light rays emitted from blue microLEDs 115 are intended to be reflected back toward lighting formation 121 , the exposed side of metal layer 155 is accessible. A heat sink (not shown) can be bonded to metal later 155 to cool the quantum dots. This cooling allows the quantum dots to be pumped harder than possible without the cooling capability, and thus increased brightness can be achieved.

[0047] As suggested above, in some cases base substrate 135 is made of glass. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of glass compositions for base substrate that may be used in relation to different embodiments.

[0048] In certain embodiments, the base substrate 135 may be formed of glass having a thickness of less than or equal to about 3 mm, for example, ranging from about 0.1 mm to about 2.5 mm, from about 0.3 mm to about 2 mm, from about 0.5 mm to about 1.5 mm, or from about 0.7 mm to about 1 mm, including all ranges and subranges therebetween. Base substrate 135 can comprise any material known in the art for use in display devices, including aluminosilicate, alkali-alumino silicate, borosilicate, alkali-borosilicate, aluminoborosilicate, alkali-aluminoborosilicate, soda lime, or other suitable glasses. Non-limiting examples of commercially available glasses suitable for use as a glass light guide include, for instance, EAGLE XG^®, Lotus™, Willow^®, Iris™, and Gorilla^® glasses from Corning Incorporated.

[0049] Some non-limiting glass compositions can include between about 50 mol % to about 90 mol% SiC , between 0 mol% to about 20 mol% AI2O3, between 0 mol% to about 20 mol% B2O3, between 0 mol% to about 20 mol% P2O5, and between 0 mol% to about 25 mol% RxO, wherein R is any one or more of Li, Na, , Rb, Cs and x is 2, or Zn, Mg, Ca, Sr or Ba and x is 1. In some embodiments, R_xO - Al₂03> 0; 0 < R_xO - AI2O3 < 15; x = 2 and R2O - A1₂0₃< 15; R₂0 - A1₂0₃< 2; x=2 and R₂0 - AI2O3 - MgO > -15; 0 < (R_xO - AI2O3) < 25, -11 < (R₂0 - AI2O3) < 11, and -15 < (R₂0 - AI2O3 - MgO) < 1 1 ; and/or -1 < (R₂0 - AI2O3) < 2 and -6 < (R2O - AI2O3 - MgO) < 1. In some embodiments, the glass comprises less than 1 ppm each of Co, Ni, and Cr. In some embodiments, the concentration of Fe is < about 50 ppm, < about 20 ppm, or < about 10 ppm. In other embodiments, Fe + 30Cr + 35Ni < about 60 ppm, Fe + 30Cr + 35Ni < about 40 ppm, Fe + 30Cr + 35Ni < about 20 ppm, or Fe + 30Cr + 35Ni < about 10 ppm. In other embodiments, the glass comprises between about 60 mol % to about 80 mol% S1O2, between about 0.1 mol% to about 15 mol% AI2O3, 0 mol% to about 12 mol% B2O3, and about 0.1 mol% to about 15 mol% R2O and about 0.1 mol% to about 15 mol% RO, wherein R is any one or more of Li, Na, K, Rb, Cs and x is 2, or Zn, Mg, Ca, Sr or Ba and x is 1.

[0050] In other embodiments, the glass composition can comprise between about 65.79 mol % to about 78.17 mol% S1O2, between about 2.94 mol% to about 12.12 mol% AI2O3, between about 0 mol% to about 1 1.16 mol% B2O3, between about 0 mol% to about 2.06 mol% L12O, between about 3.52 mol% to about 13.25 mol% Na20, between about 0 mol% to about 4.83 mol% K2O, between about 0 mol% to about 3.01 mol% ZnO, between about 0 mol% to about 8.72 mol% MgO, between about 0 mol% to about 4.24 mol% CaO, between about 0 mol% to about 6.17 mol% SrO, between about 0 mol% to about 4.3 mol% BaO, and between about 0.07 mol% to about 0.11 mol% Sn02.

[0051] In additional embodiments, the base substrate 135 can comprise glass having an RXO/AI2O3 ratio between 0.95 and 3.23, wherein R is any one or more of Li, Na, , Rb, Cs and x is 2. In further embodiments, the glass may comprise an RXO/AI2O3 ratio between 1.18 and 5.68, wherein R is any one or more of Li, Na, , Rb, Cs and x is 2, or Zn, Mg, Ca, Sr or Ba and x is 1. In yet further embodiments, the glass can comprise an R_xO - AI2O3 - MgO between -4.25 and 4.0, wherein R is any one or more of Li, Na, , Rb, Cs and x is 2. In still further embodiments, the glass may comprise between about 66 mol % to about 78 mol% S1O2, between about 4 mol% to about 1 1 mol% AI2O3, between about 4 mol% to about 11 mol% B2O3, between about 0 mol% to about 2 mol% L12O, between about 4 mol% to about 12 mol% Na20, between about 0 mol% to about 2 mol% K2O, between about 0 mol% to about 2 mol% ZnO, between about 0 mol% to about 5 mol% MgO, between about 0 mol% to about 2 mol% CaO, between about 0 mol% to about 5 mol% SrO, between about 0 mol% to about 2 mol% BaO, and between about 0 mol% to about 2 mol% Sn02.

[0052] In additional embodiments, the glass substrate can comprise a glass material including between about 72 mol % to about 80 mol% S1O2, between about 3 mol% to about 7 mol% AI2O3, between about 0 mol% to about 2 mol% B2O3, between about 0 mol% to about

2 mol% L12O, between about 6 mol% to about 15 mol% Na20, between about 0 mol% to about 2 mol% K2O, between about 0 mol% to about 2 mol% ZnO, between about 2 mol% to about 10 mol% MgO, between about 0 mol% to about 2 mol% CaO, between about 0 mol% to about 2 mol% SrO, between about 0 mol% to about 2 mol% BaO, and between about 0 mol% to about 2 mol% Sn02. In certain embodiments, the glass can comprise between about 60 mol % to about 80 mol% S1O2, between about 0 mol% to about 15 mol% AI2O3, between about 0 mol% to about 15 mol% B2O3, and about 2 mol% to about 50 mol% _xO, wherein R is any one or more of Li, Na, , Rb, Cs and x is 2, or Zn, Mg, Ca, Sr or Ba and x is 1, and wherein Fe + 30Cr + 35Ni < about 60 ppm.

[0053] In some embodiments, the base substrate 135 can comprise a color shift Ay less than 0.05, such as ranging from about -0.005 to about 0.05, or ranging from about 0.005 to about 0.015 (e.g., about -0.005, -0.004, -0.003, -0.002, -0.001 , 0, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.01 1, 0.012, 0.013, 0.014, 0.015, 0.02, 0.03, 0.04, or 0.05). In other embodiments, the glass substrate can comprise a color shift less than 0.008. According to certain embodiments, the glass substrate can have a light attenuation on (e.g., due to absorption and/or scattering losses) of less than about 4 dB/m, such as less than about

3 dB/m, less than about 2 dB/m, less than about 1 dB/m, less than about 0.5 dB/m, less than about 0.2 dB/m, or even less, e.g., ranging from about 0.2 dB/m to about 4 dB/m, for wavelengths ranging from about 420-750 nm.

[0054] Attenuation may be characterized by measuring light transmission Τι_(λ) of an input source through a transparent substrate of length L and normalizing this transmission by the source spectrum Το(λ). In units of dB/m the attenuation is given by α(λ) =- 10/Ι_*Ιθ9ιο(Τι_(λ)/Τι_(λ)) where L is the length in meters and Τι_(λ) and Τι_(λ) are measured in radiometric units. [0055] Base substrate 135 may, in some embodiments, comprise glass that is chemically strengthened, e.g., by ion exchange. During the ion exchange process, ions within a glass sheet at or near the surface of the glass sheet may be exchanged for larger metal ions, for example, from a salt bath. The incorporation of the larger ions into the glass can strengthen the sheet by creating a compressive stress in a near surface region. A corresponding tensile stress can be induced within a central region of the glass sheet to balance the compressive stress.

[0056] Ion exchange may be carried out, for example, by immersing the glass in a molten salt bath for a predetermined period of time. Exemplary salt baths include, but are not limited to, KNO3, L1NO3, NaN⁽¾, RbN⁽¾, and combinations thereof. The temperature of the molten salt bath and treatment time period can vary. It is within the ability of one skilled in the art to determine the time and temperature according to the desired application. By way of a non- limiting example, the temperature of the molten salt bath may range from about 400°C to about 800°C, such as from about 400°C to about 500°C, and the predetermined time period may range from about 4 to about 24 hours, such as from about 4 hours to about 10 hours, although other temperature and time combinations are envisioned. By way of a non-limiting example, the glass can be submerged in a KNO3 bath, for example, at about 450°C for about 6 hours to obtain a -enriched layer which imparts a surface compressive stress.

[0057] Reflective formation 136 is attached to lighting formation 121 using an optically clear adhesive 130 between a surface of base substrate 135 and transparent conductive layer 125. Optically clear adhesive 130 maybe made of any adhesive material that is capable of holding reflective formation 136 to lighting formation 121. In some embodiments, optically clear adhesive 130 is an acrylic-based liquid that is UV cured.

[0058] Turning to Figs, lb-li, various processing steps that may be used either separately or in combination to manufacture a backlight similar to microLED backlight 100 are shown in accordance with some embodiments. The processes of Figs. lb-Id are used to manufacture reflective formation 136, and the processes of Figs, le-l i are used to manufacture lighting formation 121.

[0059] Turning to Fig. lb, a view 160 of base substrate 135 is shown prior to cutting to form intervening zone dividers 140. Quantum dot layer 150 is formed over a surface of base substrate 135 using any process known in the art for forming a layer of quantum dots.

Turning to Fig. lc, the glass material of base substrate 135 is chamfered to create inverted pyramid shapes with intervening zone dividers 140. Turning to Fig. Id, a metal or other heat conducting material is deposited over the remaining portions of quantum dot layer 150 and the sides exposed by cutting base substrate 135.

[0060] Turning to Fig. l e, transparent layer 110 is provided, and conductive traces (not shown) are formed on a surface of transparent layer 110. Turning to Fig. If, blue microLEDs 115 are attached to transparent layer 110 by, for example, soldering to the conductive traces. Turning to Fig. lg, planarization layer 120 is formed between blue microLEDs 115 leaving a surface of each of microLEDs 115 exposed. Turning to Fig. lh, transparent conductive layer 125 is formed over planarization layer 120. Turning to Fig. li, scattering surface 105 is formed in and/or on the surface of transparent layer 110. At this juncture, a clear adhesive is used to bond reflective formation 136 to lighting formation 121 to make microLED backlight 100.

[0061] Turning to Fig. lj, a display 190 including microLED backlight 100 is shown in accordance with one or more embodiments. As shown, microLED backlight 100 directs component red, green and blue light rays 160 (i.e., represented as lines 160a, 160b, 160c, 160d, 160e, 160f, 160g, 160h, 160i, 160j) each represent one of a red, green or blue light ray depending upon which type of quantum dot in quantum dot layer 150 reflected the light) toward a liquid crystal display (LCD) panel 180. LCD display panel 180 may be any device known in the art that is capable of selectively gating and/or color filtering received light at respective pixel locations. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of LCD panels that may be used in relation to different embodiments.

[0062] As shown, power is applied to microLED backlight 100 causing blue microLEDs 115 to emit blue light rays (represented as lines 165a, 165b, 165c, 166a, 166b, 166c, 167a, 167b, 167c) toward reflective formation 136 where the blue light rays are reflected off of quantum dots in quantum dot layer 150. Depending upon which type of quantum dot in quantum dot layer 150 that reflects the respective blue light ray, a red or green light ray 160 is reflected or a blue light ray scattered without being color converted. A continuum of blue light rays reflecting off of quantum dot layer 150 that includes a large number of quantum dots for each of the respective red, green and blue colors results in a continuum of red, green and blue light rays 160 being reflected back toward lighting formation 121. Red, green and blue light rays 160 pass through the various transparent layers of lighting formation 121 and on to LCD panel 180. Due to the diffusion capability of transparent layer 110 and other layers, shadows resulting from blue microLEDs 115 and other non-transparent elements in the transmission path of red, green and blue light rays 160 are largely eliminated resulting in substantially uniform distribution of red, green and blue component light across the surface of LCD panel 180. LCD panel 180 can then be operated as is known in the art to pass through light of selected colors at the various pixel locations across the display.

[0063] Turning to Fig. 2a, another microLED backlight 200 is shown in accordance with various embodiments. In contrast to MicroLED backlight 100 discussed above in relation to Figs, l a-lb, microLED backlight 200 is formed without the zone dividers. MicroLED backlight 200 includes a lighting formation 221 and a reflective formation 236.

[0064] Lighting formation 221 includes a scattering surface 205 disposed over a transparent layer 210. In some embodiments, transparent layer 210 is formed of translucent alumina. Such translucent alumina acts as a circuit board connecting blue microLEDs 215 (represented as 215a, 215b, 215c) to their respective electronic power and/or control. Translucent alumina also provides a relatively high thermal conductivity (on the order of approximately 40W/m-k compared to approximately 1 W/m-k for glass). Using a material with such high thermal conductivity provides a mechanism for dissipating heat generated by blue microLEDs 215 laterally toward the edges of lighting formation 221 where a heat sink (not shown) can be mounted outside the viewing aperture. Further, the translucence of the translucent alumina helps achieve greater uniformity in RGB light reflected back by reflective formation 236 by acting as a bulk diffuser. Scattering surface 205 further enhances the diffusion caused by transparent layer 210, and as such scattering surface 205 may be any structuring or patterning of the surface of transparent layer 210 and/or material formed on the surface of transparent layer 210.

[0065] Blue microLEDs 215 (i.e., 215a, 215b, 215c) are connected to transparent layer 210 using conductive traces (not shown). In some cases, the conductive traces are metal traces to which blue microLEDs 215 are soldered. In various cases, the conductive traces are not straight, but rather can be zig-zag or herringbone pattern so as to reduce artefacts and undesirable Moire pattern. Blue microLEDs 215 may be any type of blue light emitting diode known in the art. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of blue light emitting diodes that may be used in relation to different embodiments. Blue microLEDs 215 are mounted such that the light they emit during operation is directed away from transparent layer 210. In some embodiments, blue microLEDs 215 are lateral devices where contacts to both the p-type material and the n-type material are located on the same side of the respective LED device. In other embodiments, blue microLEDs 215 are vertical devices where a contact to the p-type material is on one side of the device and the contact to the n-type material is on the other side of the device. For the purposes of this discussion, the aforementioned vertical devices are used.

[0066] Where such vertical devices are used the sidewalk of the respective microLEDs 215 are left open to allow for a contact with both the top and the bottom of the respective device to be formed. To avoid shorting between respective ones of blue microLEDs 215, a planarazation layer 220 is formed between respective blue microLEDs 215 such that it encapsulates the sides of blue microLEDs 215 while leaving the a top region of each of blue microLEDs 215 exposed. Planarization layer 220 is formed of any non-conductive, transparent material suitable for forming a layer that surrounds blue microLEDs 215. In some embodiments, planarization layer 220 is formed of a polymer. A transparent conductive layer 225 is formed over planarization layer 220 such that an electrically conductive connection is made between transparent conductive layer 225 and each of blue microLEDs 215. As such, assuming blue microLEDs 215 are the aforementioned vertical devices, and electrical contact is formed using transparent layer 210 to one side of each of blue microLEDs 215 and electrical contact is formed using transparent conductive layer 225 to the other side of each of blue microLEDs 215. Transparent conductive layer 225 may be made of any material that is both substantially transparent and electrically conductive. In some embodiments, transparent conductive layer 225 is formed of 1TO.

[0067] Reflective formation 236 includes a reflective layer 251 that is disposed over a base substrate 235. Reflective layer 251 includes a quantum dot layer 250 disposed over base substrate 235, and a metal layer 255 disposed over quantum dot layer 250. Quantum dot layer 250 includes a number of quantum dots that operate to reflect light emitted from blue microLEDs 215. In some cases, the size and shape of the quantum dots in quantum dot layer 250 are designed such that the respective quantum dots emit light in defined frequency ranges when rays of blue light from blue microLEDs 215 strike the respective quantum dots. In some embodiments when the rays of blue light from blue microLEDs 215 strike the quantum dots of quantum dot layer 250, isotropic re-emission in red, green or blue light occurs. Of note, quantum dots do not convert blue light. Rather, scattering particles such as Ti02 are included in the polymer in which the quantum dots are suspended. Some of the incoming blue light is scattered out without being color converted by quantum dots. In this way, RGB is generated.

[0068] Various approaches to fabricating the color conversion element identified as quantum dot layer 250 can be used, and thus quantum dot layer 250 may exhibit different compositions in different embodiments. As one example, a number of quantum dots may be mixed in a polymer suspension across a large sheet (e.g., by spray deposition, or slot die coating). In this embodiment, base substrate 235 is not cut or singulated into pieces matching the size of a dimming zone of reflective formation 236, rather because base substrate 235 is planar a coating of the underside is perfomed to yield the dimming zone. Such a dimming zone may be, for example, a 50x60mm area in the case of a 65-inch display with 384 zones. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a number of dimming zone sizes that may be used in relation to different embodiments.

Having quantum dot layer 250 extended to the cut sidewalls of base layer 235 may be desirable where substantial blue light emission from blue microLEDs 215 is expected to impinge on the sidewalls of base substrate 235. As another example, the color conversion element may be formed by coating a metal layer (i.e., layer 255) with quantum dots and then sealing the quantum dots the metal layer using sputtered glass, oxide or other film to yield quantum dot layer 250. The combination of quantum dot layer 250 and metal layer 255 can then be bonded to base substrate 235 using a clear adhesive. As yet another example, the quantum dots are first deposited on an underside of base substrate 235, then those quantum dots are sealed by sputtering metal on the same underside of base substrate 235 to yield the combination of quantum dot layer 250 and metal layer 255. Such a process does not require the aforementioned bonding process.

[0069] Metal layer 255 may be formed of any metal that is both reflective and capable of transferring heat. In one particular embodiment, metal later 255 is a sputtered aluminum layer. Because the quantum dots of quantum dot layer 250 are used in reflection and blue light rays emitted from blue micro LEDs 215 are intended to be reflected back toward lighting formation 221, the exposed side of metal layer 255 is accessible. A heat sink (not shown) can be bonded to metal later 255 to cool the quantum dots. This cooling allows the quantum dots to be pumped harder than possible without the cooling capability, and thus increased brightness can be achieved.

[0070] In some embodiments, base substrate 235 is made of glass. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of glass compositions for base substrate that may be used in relation to different embodiments. Some examples of such glass compositions are discussed above in relation to Fig. la. Reflective formation 236 is attached to lighting formation 221 using an optically clear adhesive 230 between a surface of base substrate 235 and transparent conductive layer 225. Optically clear adhesive 230 may be made of any adhesive material that is capable of holding reflective formation 236 to lighting formation 221. In some embodiments, optically clear adhesive 230 is an acrylic -based liquid that is UV cured.

[0071] Turning to Fig. 2b, a display 290 including microLED backlight 200 is shown in accordance with one or more embodiments. As shown, microLED backlight 200 directs component red, green and blue light rays 260 (i.e., represented as lines 260a, 260b, 260c, 260d, 260e, 260f, 260g, 260h, 260i, 260j) each represent one of a red, green or blue light ray depending upon which type of quantum dot in quantum dot layer 250 reflected the light) toward a liquid crystal display (LCD) panel 280. LCD display panel 280 may be any device known in the art that is capable of selectively gating and/or color filtering received light at respective pixel locations. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of LCD panels that may be used in relation to different embodiments.

[0072] As shown, power is applied to microLED backlight 200 causing blue microLEDs 215 to emit blue light rays (represented as lines 265a, 265b, 265c, 266a, 266b, 266c, 267a, 267b, 267c) toward reflective formation 236 where the blue light rays are reflected off of quantum dots in quantum dot layer 250. Depending upon which type of quantum dot in quantum dot layer 250 that reflects the respective blue light ray, a red, green or a blue light ray 260 is reflected. A continuum of blue light rays reflecting off of quantum dot layer 250 that includes a large number of quantum dots for each of the respective red, green and blue colors results in a continuum of red, green and blue light rays 260 being reflected back toward lighting formation 221. Red, green and blue light rays 260 pass through the various transparent layers of lighting formation 221 and on to LCD panel 280. Due to the diffusion capability of transparent layer 210 and other layers, shadows resulting from blue microLEDs 215 and other non-transparent elements in the transmission path of red, green and blue light rays 260 are largely eliminated resulting in substantially uniform distribution of red, green and blue component light across the surface of LCD panel 280. LCD panel 280 can then be operated as is known in the art to pass through light of selected colors at the various pixel locations across the display.

[0073] Turning to Fig. 3a, yet another microLED backlight 300 is shown that includes blue microLEDs 315, red and green quantum dots incorporated in a quantum dot layer 350, and a volume diffuser 305 in accordance with various embodiments. MicroLED backlight 300 includes a lighting formation 321 and a reflective formation 336 that are mechanically separated by a gap 320. Gap 320 may be filled with any gas or mixture thereof that is capable of allowing light to pass.

[0074] Lighting formation 321 includes volume diffuser 305 disposed over a transparent layer 310. In some embodiments, transparent layer 310 is formed of translucent alumina. In other embodiments, transparent layer is formed of glass. Where translucent alumina is used, it acts as a circuit board connecting blue microLEDs 315 (represented as 315a, 315b, 315c) to their respective electronic power and/or control. Translucent alumina also provides a relatively high thermal conductivity (on the order of approximately 40 W/m-k compared to approximately 1 W/m-k for glass). Using a material with such high thermal conductivity provides a mechanism for dissipating heat generated by blue microLEDs 315 laterally toward the edges of lighting formation 321 where a heat sink (not shown) can be mounted outside the viewing aperture. Of note, the translucence of the translucent alumina helps achieve greater uniformity in RGB light reflected back by reflective formation 336 by acting as a bulk diffuser, however, such a bulk diffuser is not needed in this embodiment as the diffusion function is performed by volume diffuser 305. Volume diffuser 305 may be formed of any translucent material that provides for diffusing light passing through it. In some

embodiments, volume diffuser 305 is made of a polymer such as, for example, PMMA or polycarbonate having microscopic inclusions therein that scatter light. In some cases, the inclusions are zirconia, alumina and/or titania. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of volume diffusers and materials that may be used in relation to different embodiments.

[0075] Blue microLEDs 315 (i.e., 315a, 315b, 315c) are connected to transparent layer 310 using conductive traces (not shown). In some cases, the conductive traces are metal traces to which blue microLEDs 315 are soldered. In various cases, the conductive traces are not straight, but rather can be zig-zag or herringbone pattern so as to reduce artefacts and undesirable Moire pattern. Blue microLEDs 315 may be any type of blue light emitting diode known in the art. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of blue light emitting diodes that may be used in relation to different embodiments. Blue microLEDs 315 are mounted such that the light they emit during operation is directed away from transparent layer 310. In some embodiments, blue microLEDs 315 are lateral devices where contacts to both the p-type material and the n-type material are located on the same side of the respective LED device. In other embodiments, blue microLEDs 315 are vertical devices where a contact to the p-type material is on one side of the device and the contact to the n-type material is on the other side of the device. In either case, an electrical connection is made to both the p-type material and the n-type material of blue microLEDs 315.

[0076] Reflective formation 336 includes a reflective layer 351 that is disposed over a base substrate 335. Reflective layer 351 includes a quantum dot layer 350 disposed over base substrate 335, and a metal layer 355 disposed over quantum dot layer 350. Quantum dot layer 350 includes a number of quantum dots that operate to reflect light emitted from blue microLEDs 315. In some cases, the size and shape of the quantum dots in quantum dot layer 350 are designed such that the respective quantum dots emit light in defined frequency ranges when rays of blue light from blue microLEDs 315 strike the respective quantum dots. In some embodiments when the rays of blue light from blue microLEDs 315 strike the quantum dots of quantum dot layer 350, isotropic re-emission in red, green or blue light occurs.

[0077] Various approaches to fabricating the color conversion element identified as quantum dot layer 350 can be used, and thus quantum dot layer 350 may exhibit different compositions in different embodiments. As one example, a number of quantum dots may be mixed in a polymer suspension across a large sheet (e.g., by spray deposition, or slot die coating). In some cases, an underside of base substrate 335 is coated with quantum dots which are then sealed by sputtering metal over the underside of base substrate 335 to seal the quantum dots to make a combination of metal layer 355 and quantum dot layer 350. In addition to sealing the quantum dots, metal layer 355 acts as a reflective layer. Metal layer 355 may be formed of any metal that is both reflective and capable of transferring heat. In one particular embodiment, metal later 355 is a sputtered aluminum layer. Because the quantum dots of quantum dot layer 350 are used in reflection and blue light rays emitted from blue microLEDs 315 are intended to be reflected back toward lighting formation 321, the exposed side of metal layer 355 is accessible. A heat sink (not shown) can be bonded to metal later 355 to cool the quantum dots. This cooling allows the quantum dots to be pumped harder than possible without the cooling capability, and thus increased brightness can be achieved.

[0078] In some embodiments, base substrate 335 is made of glass. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of glass compositions for base substrate that may be used in relation to different embodiments. Some examples of such glass compositions are discussed above in relation to Fig. la. Again, reflective formation 336 is mechanically suspended a defined distance from lighting formation 321. This physical separation between reflective formation 336 and lighting formation 321 may be created using structural elements (not shown) toward the edges of microLED backlight 300 such that they are outside the viewing aperture.

[0079] Turning to Fig. 3b, a display 390 including microLED backlight 300 is shown in accordance with one or more embodiments. As shown, microLED backlight 300 directs component red, green and blue light rays 360 (i.e., represented as lines 360a, 360b, 360c, 360d, 360e, 360f, 360g, 360h, 360i, 360j) each represent one of a red, green or blue light ray depending upon which type of quantum dot in quantum dot layer 350 reflected the light) toward a liquid crystal display (LCD) panel 380. Where blue microLEDs are used, the quantum dot layer 350 would have both red quantum dots and green quantum dots plus scattering particles. The wavelength reemitted (or scattered) would depend upon what was struck by the incoming blue light. LCD display panel 380 may be any device known in the art that is capable of selectively gating and/or color filtering received light at respective pixel locations. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of LCD panels that may be used in relation to different embodiments.

[0080] As shown, power is applied to microLED backlight 300 causing blue microLEDs 315 to emit blue light rays (represented as lines 365a, 365b, 365c, 366a, 366b, 366c, 367a, 367b, 367c) toward reflective formation 336 where the blue light rays are reflected off of quantum dots in quantum dot layer 350. Depending upon which type of quantum dot in quantum dot layer 350 that reflects the respective blue light ray, a red, green or a blue light ray 360 is reflected. A continuum of blue light rays reflecting off of quantum dot layer 350 that includes a large number of quantum dots for each of the respective red, green and blue colors results in a continuum of red, green and blue light rays 360 being reflected back toward lighting formation 321. Red, green and blue light rays 360 pass through the various transparent layers of lighting formation 321 and on to LCD panel 380. Due to the diffusion capability of volume diffuser 305, shadows resulting from blue microLEDs 315 and other non-transparent elements in the transmission path of red, green and blue light rays 360 are largely eliminated resulting in substantially uniform distribution of red, green and blue component light across the surface of LCD panel 380. LCD panel 380 can then be operated as is known in the art to pass through light of selected colors at the various pixel locations across the display.

[0081] Turning to Fig. 4a, yet another microLED backlight 400 that is similar to microLED backlight 300 of Figs. 3a-3b above, except that quantum dot enhancement film (QDEF) 435 used in microLED backlight 400 instead of quantum dot layer 350 and base substrate 335 of microLED backlight 300. MicroLED backlight 400 includes lighting formation 321 that was previously described and a reflective formation 436 that are mechanically separated by a gap 420. Gap 420 may be filled with any gas or mixture thereof that is capable of allowing light to pass.

[0082] Reflective formation 436 includes a metal layer 455 dispose over QDEF 435. As one example, QDEF 435 is QDEF commercially available from 3M™ and described in "3M™ Quantum Dot Enhancement Film (QDEF)" by John Van Derlofsek et al. (undated) which is available at http://multimedia.3m.com/mws/media/9853750/3mtm-quantum-dot- enhancement-film-qdef-white-paper.pdf. The entirety of the aforementioned reference is incorporated herein by reference for all purposes. It should be noted that another material with similar properties to that of the aforementioned 3M™ product can be used.

[0083] In one particular embodiment, metal later 455 is a sputtered aluminum layer.

Because QDEF 435 is used in reflecting blue light rays emitted from blue micro LEDs 315 back toward lighting formation 321, the exposed side of metal layer 455 is accessible. A heat sink (not shown) can be bonded to metal later 455 to cool the quantum dots. This cooling allows the quantum dots to be pumped harder than possible without the cooling capability, and thus increased brightness can be achieved. Similar to that discussed above in relation to Fig. 3 a, reflective formation 436 is mechanically suspended a defined distance from lighting formation 321. This physical separation between reflective formation 436 and lighting formation 321 may be created using structural elements (not shown) toward the edges of microLED backlight 400 such that they are outside the viewing aperture.

[0084] Turning to Fig. 4b, a display 490 including microLED backlight 400 is shown in accordance with one or more embodiments. As shown, microLED backlight 400 directs component red, green and blue light rays 460 (i.e., represented as lines 460a, 460b, 460c, 460d, 460e, 460f, 460g, 460h, 460i, 460j) each represent one of a red, green or blue light ray depending upon which type of quantum dot in quantum dot layer 450 reflected the light) toward a liquid crystal display (LCD) panel 480. LCD display panel 480 may be any device known in the art that is capable of selectively gating and/or color filtering received light at respective pixel locations. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of LCD panels that may be used in relation to different embodiments.

[0085] As shown, power is applied to microLED backlight 400 causing blue microLEDs 415 to emit blue light rays (represented as lines 465a, 465b, 465c, 466a, 466b, 466c, 467a, 467b, 467c) toward reflective formation 436 where the blue light rays are reflected off of quantum dots in quantum dot layer 450. Depending upon which type of quantum dot in quantum dot layer 450 that reflects the respective blue light ray, a red, green or a blue light ray 460 is reflected. A continuum of blue light rays reflecting off of quantum dot layer 450 that includes a large number of quantum dots for each of the respective red, green and blue colors results in a continuum of red, green and blue light rays 460 being reflected back toward lighting formation 421. Red, green and blue light rays 460 pass through the various transparent layers of lighting formation 321 and on to LCD panel 480. Due to the diffusion capability of volume diffuser 305, shadows resulting from blue microLEDs 315 and other non-transparent elements in the transmission path of red, green and blue light rays 460 are largely eliminated resulting in substantially uniform distribution of red, green and blue component light across the surface of LCD panel 480. LCD panel 480 can then be operated as is known in the art to pass through light of selected colors at the various pixel locations across the display.

[0086] Turning to Fig. 5a, yet another microLED backlight 500 using phosphor converted white microLEDs 515 (represented as 515a, 515b, 515c) is shown in accordance with other embodiments. MicroLED backlight 500 includes lighting formation 521 and a reflector layer 555. Reflector layer may formed of any material capable of reflecting light emitted from phosphor converted white microLEDs 515. Additionally, in those embodiments where reflector layer 555 is a stand alone layer without other structural support, the material used to form reflector layer 555 should be strong enough to be self supporting. In some

embodiments, reflector layer 555 is made of metal. In one particular embodiment, reflector layer 555 is made of aluminum. Lighting formation 521 and reflector layer 555 are mechanically separated by a gap 520. Gap 520 may be filled with any gas or mixture thereof that is capable of allowing light to pass.

[0087] Lighting formation 521 includes volume diffuser 505 disposed over a transparent layer 510. In some embodiments, transparent layer 510 is formed of translucent alumina. In other embodiments, transparent layer is formed of glass. Where translucent alumina is used, it acts as a circuit board connecting phosphor converted white microLEDs 515 to their respective electronic power and/or control. Translucent alumina also provides a relatively high thermal conductivity (on the order of approximately 40W/m-k compared to

approximately 1 W/m-k for glass). Using a material with such high thermal conductivity provides a mechanism for dissipating heat generated by blue microLEDs 515 laterally toward the edges of lighting formation 521 where a heat sink (not shown) can be mounted outside the viewing aperture. Of note, the translucence of the translucent alumina helps achieve greater uniformity in RGB light reflected back by reflective formation 536 by acting as a bulk diffuser, however, such a bulk diffuser is not needed in this embodiment as the diffusion function is performed by volume diffuser 505. Volume diffuser 505 may be formed of any translucent material that provides for diffusing light passing through it. In some embodiments, volume diffuser 505 is made of a polymer such as, for example, PMMA or polycarbonate having microscopic inclusions therein that scatter light. In some cases, the inclusions are zirconia, alumina and/or titania. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of volume diffusers and materials that may be used in relation to different embodiments.

[0088] Phosphor converted white microLEDs 515 (i.e., 515a, 515b, 515c) are connected to transparent layer 510 using conductive traces (not shown). In some cases, the conductive traces are metal traces to which phosphor converted white microLEDs 515 are soldered. In various cases, the conductive traces are not straight, but rather can be zig-zag or herringbone pattern so as to reduce artefacts and undesirable Moire pattern. Phosphor converted white microLEDs 515 may be any type of white light emitting diode known in the art. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of white light emitting diodes that may be used in relation to different embodiments. Phosphor converted white microLEDs 515 are mounted such that the light they emit during operation is directed away from transparent layer 510. In some embodiments, phosphor converted white microLEDs 515 are lateral devices where contacts to both the p-type material and the n-type material are located on the same side of the respective LED device. In other embodiments, phosphor converted white microLEDs 515 are vertical devices where a contact to the p-type material is on one side of the device and the contact to the n-type material is on the other side of the device. In either case, an electrical connection is made to both the p-type material and the n-type material of phosphor converted white microLEDs 515.

[0089] Similar to that discussed above in relation to Fig. 5a, reflector layer 555 is mechanically suspended a defined distance from lighting formation 521. This physical separation between reflector layer 555 and lighting formation 521 maybe created using structural elements (not shown) toward the edges of microLED backlight 500 such that they are outside the viewing aperture.

[0090] Turning to Fig. 5b, a display 590 including microLED backlight 500 is shown in accordance with one or more embodiments. As shown, microLED backlight 500 directs white light rays 560 (i.e., represented as lines 560a, 560b, 560c, 560d, 560e, 560f, 560g, 560h, 560i, 560j) reflected off reflector layer 555 toward a liquid crystal display (LCD) panel 580. LCD display panel 580 may be any device known in the art that is capable of selectively gating and/or color filtering received light at respective pixel locations. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of LCD panels that may be used in relation to different embodiments.

[0091] As shown, power is applied to micro LED backlight 500 causing phosphor converted white microLEDs 515 to emit white light rays (represented as lines 565a, 565b, 565c, 566a, 566b, 566c, 567a, 567b, 567c) toward reflector layer 555 where the white light rays are reflected back toward lighting formation 521. White light rays 560 pass through the various transparent layers of lighting formation 521 and on to LCD panel 580. Due to the diffusion capability of volume diffuser 505, shadows resulting from phosphor converted white microLEDs 315 and other non-transparent elements in the transmission path of white light rays 560 are largely eliminated resulting in substantially uniform distribution of light across the surface of LCD panel 580. LCD panel 580 can then be operated as is known in the art to pass through light of selected colors at the various pixel locations across the display.

[0092] Turning to Fig. 6a, yet another microLED backlight 600 using RGB microLEDs 615 (represented as 615a, 615b, 615c) is shown in accordance with other embodiments. MicroLED backlight 600 includes lighting formation 621 and a reflector layer 655. Reflector layer may formed of any material capable of reflecting light emitted from RGB microLEDs 615. Additionally, in those embodiments where reflector layer 655 is a stand alone layer without other structural support, the material used to form reflector layer 655 should be strong enough to be self supporting. In some embodiments, reflector layer 655 is made of metal. In one particular embodiment, reflector layer 655 is made of aluminum. Lighting formation 621 and reflector layer 655 are mechanically separated by a gap 620. Gap 620 may be filled with any gas or mixture thereof that is capable of allowing light to pass.

[0093] Lighting formation 621 includes volume diffuser 605 disposed over a transparent layer 610. In some embodiments, transparent layer 610 is formed of translucent alumina. In other embodiments, transparent layer is formed of glass. Where translucent alumina is used, it acts as a circuit board connecting RGB microLEDs 615 to their respective electronic power and/or control. Translucent alumina also provides a relatively high thermal conductivity (on the order of approximately 40W/m-k compared to approximately 1 W/m-k for glass). Using a material with such high thermal conductivity provides a mechanism for dissipating heat generated by blue microLEDs 615 laterally toward the edges of lighting formation 621 where a heat sink (not shown) can be mounted outside the viewing aperture. Of note, the translucence of the translucent alumina helps achieve greater uniformity in RGB light reflected back by reflective formation 636 by acting as a bulk diffuser, however, such a bulk diffuser is not needed in this embodiment as the diffusion function is performed by volume diffuser 605. Volume diffuser 605 may be formed of any translucent material that provides for diffusing light passing through it. In some embodiments, volume diffuser 605 is made of a polymer such as, for example, PMMA or polycarbonate having microscopic inclusions therein that scatter light. In some cases, the inclusions are zirconia, alumina and/or titania. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of volume diffusers and materials that may be used in relation to different embodiments.

[0094] RGB micro LEDs 615 (i.e., 615a, 615b, 615c) are connected to transparent layer 610 using conductive traces (not shown). In some cases, the conductive traces are metal traces to which RGB microLEDs 615 are soldered. In various cases, the conductive traces are not straight, but rather can be zig-zag or herringbone pattern so as to reduce artefacts and undesirable Moire pattern. RGB microLEDs 615 may be any type of white light emitting diode known in the art. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of white light emitting diodes that may be used in relation to different embodiments. RGB microLEDs 615 are mounted such that the light they emit during operation is directed away from transparent layer 610. In some embodiments, RGB microLEDs 615 are lateral devices where contacts to both the p-type material and the n-type material are located on the same side of the respective LED device. In other embodiments, RGB microLEDs 615 are vertical devices where a contact to the p-type material is on one side of the device and the contact to the n-type material is on the other side of the device. In either case, an electrical connection is made to both the p-type material and the n-type material of RGB microLEDs 615.

[0095] Similar to that discussed above in relation to Fig. 6a, reflector layer 655 is mechanically suspended a defined distance from lighting formation 621. This physical separation between reflector layer 655 and lighting formation 621 maybe created using structural elements (not shown) toward the edges of microLED backlight 600 such that they are outside the viewing aperture. [0096] Turning to Fig. 6b, a display 690 including microLED backlight 600 is shown in accordance with one or more embodiments. As shown, microLED backlight 600 directs component red, green and blue light rays light rays 660 (i.e., represented as lines 660a, 660b, 660c, 660d, 660e, 660f, 660g, 660h, 660i, 660j) reflected off reflector layer 655 toward a liquid crystal display (LCD) panel 680. LCD display panel 680 may be any device known in the art that is capable of selectively gating and/or color filtering received light at respective pixel locations. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of LCD panels that may be used in relation to different embodiments.

[0097] As shown, power is applied to microLED backlight 600 causing RGB microLEDs 615 to respectively emit component red, green or blue light rays (represented as lines 665a, 665b, 665c, 666a, 666b, 666c, 667a, 667b, 667c) toward reflector layer 655 where the component red, green or blue light rays are reflected back toward lighting formation 621. Component red, green and blue light rays 660 pass through the various transparent layers of lighting formation 621 and on to LCD panel 680. Due to the diffusion capability of volume diffuser 605, shadows resulting from RGB microLEDs 615 and other non-transparent elements in the transmission path of white light rays 660 are largely eliminated resulting in substantially uniform distribution of light across the surface of LCD panel 680. LCD panel 680 can then be operated as is known in the art to pass through light of selected colors at the various pixel locations across the display.

[0098] Turning to Fig. 7a, another microLED backlight 700 is shown using bottom firing RGB microLEDs 715 (represented as 715a, 715b, 715c) in accordance with various embodiments. MicroLED backlight 700 includes a transparent substrate 720. In some embodiments, transparent substrate 720 is formed of glass, translucent alumina, or some other transparent material.

[0099] RGB microLEDs 715 (i.e., 715a, 715b, 715c) are connected to transparent layer 710 using conductive traces (not shown). In some cases, the conductive traces are metal traces to which RGB microLEDs 715 are soldered. In various cases, the conductive traces are not straight, but rather can be zig-zag or herringbone pattern so as to reduce artefacts and undesirable Moire pattern. RGB microLEDs 715 may be any type of red, green or blue light emitting diode known in the art. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of RGB light emitting diodes that may be used in relation to different embodiments. RGB micro LEDs 715 are mounted such that the light they emit during operation is directed toward a diffuse reflector 755 formed on an opposite surface of transparent substrate 720. In some embodiments, RGB micro LEDs 715 are lateral devices where contacts to both the p-type material and the n-type material are located on the same side of the respective LED device. In other embodiments, RGB microLEDs 715 are vertical devices where a contact to the p-type material is on one side of the device and the contact to the n-type material is on the other side of the device.

[00100] Use of translucent alumina transparent substrate 720 provides some advantages as its conductivity provides an ability to operate as a circuit board connecting RGB microLEDs 715 (represented as 715a, 715b, 715c) to their respective electronic power and/or control. Translucent alumina also provides a relatively high thermal conductivity (on the order of approximately 40W/m-k compared to approximately 1 W/m-k for glass). Using a material with such high thermal conductivity provides a mechanism for dissipating heat generated by RGB microLEDs 715 laterally toward the edges of microLED backlight 700 where a heat sink (not shown) can be mounted outside the viewing aperture. Further, the translucence of the translucent alumina helps achieve greater uniformity in RGB light reflected back by diffuse reflector 755. Diffuse reflector 755 may be formed of any material capable of reflecting light emitted from RGB microLEDs 715 back through transparent substrate 720. In one particular embodiment, diffuse reflector 755 is made of sputtered aluminum on a roughened substrate.

[00101] Turning to Fig. 7b, a display 790 including microLED backlight 700 is shown in accordance with one or more embodiments. As shown, microLED backlight 700 directs component red, green and blue light rays 760 (i.e., represented as lines 760a, 760b, 760c, 760d, 760e, 760f, 760g, 760h, 760i, 760j) reflected off reflector layer 655 toward a liquid crystal display (LCD) panel 680. LCD display panel 680 may be any device known in the art that is capable of selectively gating and/or color filtering received light at respective pixel locations. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of LCD panels that may be used in relation to different embodiments.

[00102] As shown, power is applied to microLED backlight 700 causing RGB microLEDs 715 to emit component red, green and blue light rays (represented as lines 765a, 765b, 765c, 766a, 766b, 766c, 767a, 767b, 767c), respectively toward diffuse reflector 755. This results in a continuum of red, green and blue light rays 760 being reflected back through translucent substrate 720 and toward LCD panel 780. LCD panel 780 can then be operated as is known in the art to pass through light of selected colors at the various pixel locations across the display.

[00103] Turning to Fig. 8a, another microLED backlight 800 is shown using bottom firing blue microLEDs 815 (represented as 815a, 815b, 815c) in accordance with various embodiments. MicroLED backlight 800 includes a transparent substrate 820. In some embodiments, transparent substrate 820 is formed of glass, translucent alumina, or some other transparent material. A reflector formation 836 is disposed on one side of transparent substrate and includes a quantum dot layer 850 and a metal layer 855.

[00104] Blue microLEDs 815 (i.e., 815a, 815b, 815c) are connected to transparent layer 810 using conductive traces (not shown). In some cases, the conductive traces are metal traces to which blue microLEDs 815 are soldered. In various cases, the conductive traces are not straight, but rather can be zig-zag or herringbone pattern so as to reduce artefacts and undesirable Moire pattern. Blue microLEDs 815 may be any type of blue light emitting diode known in the art. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of blue light emitting diodes that may be used in relation to different embodiments. Blue microLEDs 815 are mounted such that the light they emit during operation is directed toward reflector formation 836 disposed on an opposite surface of transparent substrate 820. In some embodiments, blue microLEDs 815 are lateral devices where contacts to both the p-type material and the n-type material are located on the same side of the respective LED device. In other embodiments, blue microLEDs 815 are vertical devices where a contact to the p-type material is on one side of the device and the contact to the n-type material is on the other side of the device.

[00105] Use of translucent alumina for transparent substrate 820 provides some advantages as its conductivity provides an ability to operate as a circuit board connecting blue microLEDs 815 (represented as 815a, 815b, 815c) to their respective electronic power and/or control. Translucent alumina also provides a relatively high thermal conductivity (on the order of approximately 40W/m-k compared to approximately 1 W/m-k for glass). Using a material with such high thermal conductivity provides a mechanism for dissipating heat generated by blue microLEDs 815 laterally toward the edges of microLED backlight 800 where a heat sink (not shown) can be mounted outside the viewing aperture. Further, the translucence of the translucent alumina helps achieve greater uniformity in RGB light reflected back by quantum dots included in quantum dot layer 850.

[00106] Quantum dot layer 850 includes a number of quantum dots that operate to reflect light emitted from blue microLEDs 315. In some cases, the size and shape of the quantum dots in quantum dot layer 850 are designed such that the respective quantum dots emit light in defined frequency ranges when rays of blue light from blue microLEDs 815 strike the respective quantum dots. In some embodiments when the rays of blue light from blue microLEDs 815 strike the quantum dots of quantum dot layer 850, isotropic re-emission in red, green or blue light occurs. Various approaches to fabricating the color conversion element identified as quantum dot layer 850 can be used, and thus quantum dot layer 850 may exhibit different compositions in different embodiments. As one example, a number of quantum dots may be mixed in a polymer suspension across a large sheet (e.g., by spray deposition, or slot die coating).

[00107] Metal layer 855 acts both as a reflective layer and to seal the quantum dots of quantum dot layer 850. Metal layer 855 is formed after base substrate 820 is cut, and thus metal layer 855 extends to cover the cut sidewalls of base substrate 820. Metal layer 855 may be formed of any metal that is both reflective and capable of transferring heat. In one particular embodiment, metal later 855 is a sputtered aluminum layer. Because the quantum dots of quantum dot layer 850 are used in reflection and blue light rays emitted from blue microLEDs 815 are intended to be reflected back through transparent layer 820, the exposed side of metal layer 855 is accessible. A heat sink 895 can be bonded to metal later 855 to cool the quantum dots. This cooling allows the quantum dots to be pumped harder than possible without the cooling capability, and thus increased brightness can be achieved.

[00108] Turning to Fig. 8b, a display 890 including microLED backlight 800 is shown in accordance with one or more embodiments. As shown, microLED backlight 800 directs component red, green and blue light rays 860 (i.e., represented as lines 860a, 860b, 860c, 860d, 860e, 860f, 860g, 860h, 860i, 860j) reflected off reflector formation 836 toward a liquid crystal display (LCD) panel 680. LCD display panel 680 may be any device known in the art that is capable of selectively gating and/or color filtering received light at respective pixel locations. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of LCD panels that may be used in relation to different embodiments.

[00109] As shown, power is applied to microLED backlight 800 causing blue microLEDs 815 to emit component blue light rays (represented as lines 865a, 865b, 865c, 866a, 866b, 866c, 867a, 867b, 867c), respectively toward reflector formation 836 where the blue light rays are reflected off of quantum dots in quantum dot layer 850. Depending upon which type of quantum dot in quantum dot layer 850 that reflects the respective blue light ray, a red, green or a blue light ray 860 is reflected. A continuum of blue light rays reflecting off of quantum dot layer 850 that includes a large number of quantum dots for each of the respective red, green and blue colors results in a continuum of red, green and blue light rays 360 being reflected back through transparent substrate 820 and on to LCD panel 880. LCD panel 880 can then be operated as is known in the art to pass through light of selected colors at the various pixel locations across the display.

[00110] Turning to Fig. 9, a flow diagram 900 shows a method for making a backlit display in accordance with various embodiments. Following flow diagram 900, a substrate having a first side and a second side is provided (block 905). The substrate is formed of a transparent material such as, for example, glass or translucent alumina.

[00111] A reflective material is formed on the substrate (block 910). In some embodiments, the reflective material includes a color converter such as, for example, a quantum dot layer made of a suspension of quantum dots in a polymer. In such a case, forming the quantum dot layer includes spray deposition or slot die coating of the suspension on a surface of the substrate. In other embodiments, the reflective material is a QDEF bonded to the substrate. In yet other embodiments, the reflective material is a metal that may be, for example, sputtered onto a surface of the substrate. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of materials that may be applied to a surface of the substrate to form a reflective layer. In some cases, the reflective material is a combination of material layers including, for example, a quantum dot layer and a metal layer, or a QDEF and a metal layer.

[00112] An electrically conductive material is formed on a portion of an opposite surface of the substrate (block 915). This electrically conductive material provides locations to which microLEDs can be bonded to the substrate. In some embodiments, the electrical material is a metal formed over the substrate using a deposition and lithography process. A number of microLEDs are bonded to the substrate at locations where the aforementioned electrical material exists such that some of the electrical material operates as contacts to the microLEDs (block 920). The microLEDs are bonded to the substrate in an orientation where light emitted from the microLEDs is directed through the substrate toward the reflective material on the opposite side of the substrate. At this juncture, a lighting formation or light source has been made. This lighting formation or light source is assembled relative to an LCD panel such that light reflected from the reflective material back through the substrate impinges on the LCD panel (block 925). While not shown, in some cases a heat sink may be bonded to the reflective layer and/or to sides of the substrate outside the aperture of the resulting display.

[00113] Turning to Fig. 10, a flow diagram 1000 shows another method for making a backlit display in accordance with some embodiments. Following flow diagram 1000, a substrate having a first side and a second side is provided (block 1005). The substrate is formed of a transparent material such as, for example, glass or translucent alumina.

[00114] A light diffuser is formed over one side of the substrate (block 1010), and an electrically conductive material is formed over the opposite side of the substrate (block 1015). This electrically conductive material provides locations to which microLEDs can be bonded to the substrate. In some embodiments, the electrical material is a metal formed over the substrate using a deposition and lithography process. A number of microLEDs are bonded to the substrate at locations where the aforementioned electrical material exists such that some of the electrical material operates as contacts to the microLEDs (block 1020). The microLEDs are bonded to the substrate in an orientation where light emitted from the microLEDs is directed away from the substrate.

[00115] In addition, a reflective layer is provided (block 1040). The reflective layer may be, for example, a substrate made of a reflective material such as metal. Alternatively, the reflective layer may be a glass substrate to which a reflective color converter and/or a metal layer have been bonded. The aforementioned color converter may be, for example, a quantum dot layer or a QDEF. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of reflective layers that may be used in relation to different embodiments. [00116] The substrate (including the microLEDs) is assembled relative to the reflective layer such that the microLEDs on the substrate emit light toward the reflective layer (block 1050). This assembly may include, for exam le, bonding the substrate to the reflective layer. As another example, the aforementioned assembly may include attaching structural elements outside the aperture of the resulting lighting formation. Based upon the disclosure provided herein, one of ordinary skill in the art will recognize a variety of ways in which the substrate may be assembled relative to the reflective layer. At this juncture, a lighting formation or light source has been made. This lighting formation or light source is assembled relative to an LCD panel such that light reflected from the reflective material back through the substrate impinges on the LCD panel (block 1050). While not shown, in some cases a heat sink may be bonded to the reflective layer and/or to sides of the substrate outside the aperture of the resulting display.

[00117] Turning to Fig. 11 , a conventional backlit display 1101 is shown alongside a reflective backlit display 1100 in accordance with some embodiments to demonstrate the reduction in display thickness that can be achieved using embodiments. It should be noted that the demonstrated reduction in display thickness is applicable to any of the display embodiments discussed herein.

[00118] As shown, conventional backlit display 1 101 has a backlight substrate 1121 to which a microLED 1116 is attached, and an LCD panel 1181. In order to achieve a dispersion width (shown as W) of light (1106a, 1106b) emitted from microLED 1 116 at an angle 1130, LCD panel 1181 must be placed a distance (shown as D3) away from the surface of backlight substrate 1 121 to which microLED 11 16 is attached. This results in an overall display thickness of D 1.

[00119] Reflective backlit display 1 100 has a backlight substrate 1 120 to which a microLED 1115 is attached, and an LCD panel 1180. MicroLED is oriented such that it emits light through backlit substrate toward a reflective layer 1150 on the opposite side of backlight substrate 1120. In such an orientation, light (1105a, 1105b) emitted from microLED 1115 at an angle 1130 passes through substrate 1120 and is reflected off of reflective layer 1150 as light 1110a, 1110b. In order to achieve the same dispersion width (shown as W) as that of conventional backlit display 1101 for light (1110a, 1 110b) re-emitted off reflective layer 1120. LCD panel 1180 only has to be placed a distance (shown as D4) away from the surface of backlight substrate 1 120 to which microLED 11 16 is attached. Of note, D4 is considerably less than D3. This results in an overall display thickness of D2 which is similarly much less than Dl . Thus, as one of many advantages achievable by using embodiments disclosed herein is the capability of producing thinner LCD displays.

[00120] In conclusion, the invention provides novel systems, devices, methods and arrangements for providing lighting. While detailed descriptions of one or more

embodiments of the invention have been given above, various alternatives, modifications, and equivalents will be apparent to those skilled in the art without varying from the spirit of the invention. For example, reflective layers are often described as being implemented in metal, but could be implemented in other materials including, but not limited to, white paint.

Therefore, the above description should not be taken as limiting the scope of the invention, which is defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. An LCD display apparatus, the apparatus comprising: an LCD panel; and

a micro light emitting diode (microLED) backlight in a fixed position relative to the LCD panel, wherein the microLED backlight includes:

a reflective formation;

a transparent substrate; and

at least one microLED device, wherein the at least one microLED device is disposed in relation to the reflective formation and the transparent substrate such that light emitted from the at least one microLED device both reflects off the reflective formation and passes through the transparent substrate before reaching the LCD panel.

2. The apparatus of claim 1, wherein the apparatus further comprises: a heat sink bonded to the reflective formation.

3. The apparatus of claim 1, wherein the transparent substrate is a first transparent substrate, and wherein the reflective formation is selected from a group consisting of:

(a) a quantum dot layer formed over a second substrate, and a metal layer formed over the quantum dot layer;

(b) a quantum dot enhancement film;

(c) a quantum dot enhancement film with a metal layer formed over one surface of the quantum dot enhancement film;

(d) a metal layer;

(e) a diffuse reflector disposed over a surface of the first substrate; and

(f) a quantum dot layer formed over a surface of the first substrate, and a metal layer formed over the quantum dot layer.

4. The apparatus of claim 1, wherein the transparent substrate is formed of a material selected from a group consisting of: glass, and translucent alumina.

5. The apparatus of claim 1, wherein the at least one micro LED is a white LED, and wherein the reflective formation is selected from a group consisting of:

(a) a metal layer;

(b) a diffuse reflector disposed over a surface of the substrate; and

(c) white paint.

6. The apparatus of claim 1, wherein the substrate is a first substrate, wherein the at least one microLED is a blue LED, and wherein the reflective formation is selected from a group consisting of:

(b) a quantum dot enhancement film;

(c) a quantum dot enhancement film with a metal layer formed over one surface of the quantum dot enhancement film; and

(d) a quantum dot layer formed over a surface of the first substrate, and a metal layer formed over the quantum dot layer.

7. The apparatus of claim 1, wherein the at least one microLED includes a red LED, a green LED, and a blue LED, and wherein the reflective formation is selected from a group consisting of:

(a) a metal layer;

(b) a diffuse reflector disposed over a surface of the substrate; and

(c) white paint.

8. A backlight device, the device comprising:

a transparent substrate;

a reflective formation formed on a first side of the transparent substrate; at least one micro light emitting diode (microLED) disposed over a second side of the transparent substrate, wherein the at least one microLED is oriented such that light emitted from the at least one microLED passes through the transparent substrate and is reflected off the reflective formation to yield reflected light, and wherein the reflected light passes through the transparent substrate before being provided as a light output from the backlight device.

9. The device of claim 7, wherein the reflective formation includes a metal layer, and wherein the device further includes:

a heat sink bonded to the metal layer.

10. The device of claim 7, wherein the at least one micro LED includes a blue LED, and wherein the reflective formation includes:

a quantum dot layer operable to color convert blue light emitted from the blue LED to reflect red, green and blue component light.

11. The device of claim 10, wherein the quantum dot layer is disposed on the transparent substrate, and wherein the quantum dot layer is sealed by a metal layer.

12. The device of claim 7, wherein the at least one microLED includes a red LED, a green LED and a blue LED, and wherein the reflective formation includes:

a diffuse reflector disposed on the transparent substrate.

13. The device of claim 7, wherein the at least one microLED includes a blue LED, and wherein the reflective formation includes:

a quantum dot enhancement film operable to color convert blue light emitted from the blue LED to reflect red, green and blue component light.

14. The device of claim 7, wherein the transparent substrate is made of translucent alumina.

15. The device of claim 7, wherein the transparent substrate is made of glass.

16. A backlight device, the device comprising:

a lighting formation, the lighting formation including: a transparent substrate; and

at least one micro light emitting diode (microLED) disposed on a surface of the transparent substrate, wherein the at least one microLED is oriented such that light emitted from the at least one microLED is directed away from the transparent substrate; and

a reflective formation including a reflective layer, and wherein the reflective formation is positioned in relation to the lighting formation such that light emitted from the at least one microLED reflects off the reflective layer as reflected light, and wherein the reflected light passes through the transparent substrate as a light output from the backlight device.

17. The device of claim 16, wherein the reflective formation includes a metal layer, and wherein the device further includes:

a heat sink bonded to the metal layer.

18. The device of claim 16, wherein the transparent substrate is translucent alumina.

19. The device of claim 16, wherein the transparent substrate is glass.

20. The device of claim 16, wherein surface of the transparent substrate on which the at least one microLED is disposed is a first surface of the transparent substrate, and wherein the lighting formation further includes a glass volume diffuser formed on a second surface of the transparent substrate.

21. The device of claim 16, wherein the at least one microLED is a blue LED, and wherein the reflective layer includes:

a quantum dot enhancement film operable to color convert blue light emitted from the blue LED to reflect red, green and blue component light; and

a metal layer deposited on the quantum dot enhancement film.

22. The device of claim 16, wherein the transparent substrate is a first transparent substrate, and wherein the reflective formation comprises: the reflective layer disposed on a second transparent substrate, wherein light emitted from the at least one microLED passes through the second substrate before being reflected off the reflective layer.

23. The device of claim 22, wherein the at least one microLED is a blue LED, and wherein the reflective layer includes a quantum dot layer formed on the second transparent substrate, and a metal layer formed over the quantum dot layer.

24. The device of claim 23, wherein a zone divider is formed in the second transparent substrate, wherein the zone divider exhibits a tapered wall extending at least part way between a first surface of the second transparent substrate and a second surface of the second transparent substrate.

25. The device of claim 24, wherein the tapered sidewall of the second transparent substrate is covered with a metal layer.

26. The device of claim 25, wherein the tapered sidewall of the second transparent substrate is covered with both a quantum dot layer and a metal layer.

27. The device of claim 16, wherein the at least one microLED includes a red LED, a green LED, and a blue LED, and wherein the reflective layer is selected from a group consisting of:

(a) a metal layer;

(b) a diffuse reflector; and

(c) white paint.

28. The device of claim 16, wherein the at least one microLED is a white LED, and wherein the reflective layer is selected from a group consisting of:

(a) a metal layer;

(b) a diffuse reflector disposed over a surface of the substrate; and

(c) white paint.