WO2022098683A1

WO2022098683A1 - Optical display device with ambient contrast enhancement and method of making

Info

Publication number: WO2022098683A1
Application number: PCT/US2021/057803
Authority: WO
Inventors: Sang-Cheol Jung; Dae Youn Kim; Goo Soo Lee; Kyung-Jin Lee; Dong Keun Shin; Hong Yoon
Original assignee: Corning Incorporated
Priority date: 2020-11-06
Filing date: 2021-11-03
Publication date: 2022-05-12
Also published as: TW202226585A; JP2023548602A; CN116490988A

Abstract

An optical display device having a backplane substrate and an ambient contrast filter disposed over the backplane substrate. The backplane substrate includes a plurality of electroluminescent elements and the ambient contrast filter includes a plurality of light absorbing wedge-shaped features arranged in rows. In some embodiments, the ambient contrast filter may include a glass substrate layer.

Description

OPTICAL DISPLAY DEVICE WITH AMBIENT CONTRAST ENHANCEMENT AND

METHOD OF MAKING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S C. § 119 of Korean Patent Application Serial No. 10-2020-0147757 filed on November 06, 2020 the content of which is relied upon and incorporated herein by reference in its entirety.

FIELD

[0002] The present disclosure relates to an optical display device, and more particularly an optical display device including an ambient contrast enhancement layer configured to improve contrast in a displayed image in the presence of ambient light.

BACKGROUND

[0003] Ambient light contrast can be an issue for self-emissive electro-luminescent displays like organic light emitting diode (OLED) and micro-light emitting diode (micro-LED) displays. Display panels with surfaces that include metallic electrodes and/or other reflective materials can reflect light from solar radiation or indoor lighting. For instance, OLED panels can have almost 80% surface reflectivity, primarily from metallic electrodes. Circular polarizers are often used as an optically functional film to reduce ambient light reflection and avoid a loss of display contrast ratio. However, such polarizing films can absorb up to 50% of incident light, thereby potentially reducing display brightness.

SUMMARY

[0004] An optical display device comprising an ambient contrast enhancement layer adjacent to a backplane substrate is described. The backplane substrate can include a plurality of electroluminescent elements deposited thereon. The ambient contrast enhancement layer can include a plurality of light absorbing wedge-shaped features arranged in rows.

[0005] Accordingly, an optical display device is disclosed comprising a backplane substrate including a plurality of electroluminescent elements deposited in parallel rows thereon, each row of electroluminescent elements comprising an alignment axis. The display device further comprises an ambient contrast filter positioned over the backplane substrate, the ambient contrast filter comprising a polymer support layer and a micro-replicated thin film base layer disposed on the polymer support layer, the micro-replicated thin film base layer comprising a plurality of light absorbing wedge-shaped features arranged in parallel rows, each light absorbing wedge-shaped feature comprising a longitudinal axis. Additionally, the ambient contrast filter does not include a glass substrate layer.

[0006] The ambient contrast filter may further comprise a light absorbing layer disposed on the micro-replicated thin film base layer. A thickness of the light absorbing layer can be in a range from about 10 nm to about 1 pm.

[0007] A height Hl of the plurality of wedge-shaped features may be in a range from about 10 pm to about 100 pm, such as in a range from about 10 pm to about 40 pm.

[0008] Each wedge-shaped feature of the plurality of wedge-shaped features may comprise a first maximum cross-sectional width W1 in a range from about 5 pm to about 15 pm.

[0009] A ratio Hl/Wl can be equal to or greater than about 2, for example in a range from about 2 to about 6.

[0010] A pitch Pl of the plurality of wedge-shaped features may be in a range from about 5 pm to about 40 pm.

[0011] An angle between a base of each wedge-shaped feature of the plurality of wedge- shaped features and an adjacent side wall of each wedge-shaped feature may be in a range from about 85 degrees to less than 90 degrees.

[0012] The ambient contrast filter may comprise an anti-reflection layer. For example, the anti-reflection layer may be disposed on the light absorbing layer

[0013] The index of refraction of the plurality of wedge-shaped features is HB and an index of refraction of the micro-replicated thin film base layer is nr, and An = rn>,-ni; and -0.3 < An < 0. [0014] A method of forming an ambient contrast filter is also described, the method comprising rotating a first patterning roller in a first direction, the first patterning roller comprising a first circumferential surface including a plurality of protrusions extending therefrom. The method may further comprise rotating a first support roller in a second direction opposite the first direction, the first support roller comprising a second circumferential surface spaced from the first circumferential surface by a first gap. The method may include rotating a second support roller in the second direction, the second support roller comprising a third circumferential surface, the third circumferential surface spaced from the first circumferential surface by a second gap, the first patterning roller positioned between the first support roller and the second support roller. The method includes directing a polymer support layer into the first gap, dispensing a polymer matrix material into the first gap between the support layer and the first circumferential surface of the first patterning roller, the first patterning roller forming a plurality of recesses in the polymer matrix material, and irradiating the support layer and the polymer matrix material with a first UV light, the first UV light curing the polymer matrix material to form a micro -replicated thin film base layer bonded to the support layer, the microreplicated thin film base layer and the support layer forming a micro-replicated thin film.

[0015] The method may further comprise directing the micro-replicated thin film into a third gap between the third circumferential surface of the second support roller and a fourth circumferential surface of an application roller rotating in the first direction; dispensing a light absorbing material into the third gap between the micro-replicated thin film and the fourth circumferential surface of the application roller, the light absorbing material filling the recesses; and irradiating the light absorbing material with a second UV light to at least partially cure the light absorbing material and form a plurality of light absorbing wedge-shaped features in the micro-replicated thin film base layer. The support layer, the micro-replicated thin film base layer, and the plurality of light absorbing wedge-shaped features form an ambient contrast enhancement layer.

[0016] The method may still further comprise directing the ambient contrast enhancement layer into a fourth gap between a fifth circumferential surface of a third support roller downstream of the application roller and a sixth circumferential surface of a second patterning roller, dispensing a second polymer material into the third gap between the ambient contrast enhancement layer and the fifth circumferential surface of the third support roller, and irradiating the second polymer material with a third UV light to at least partially cure the second polymer material, the cured second polymer material forming an IR layer bonded to the ambient contrast enhancement layer.

[0017] The second patterning roller may comprise a roughened circumferential surface.

[0018] Additional features and advantages of the embodiments disclosed herein will be set forth in the detailed description that follows, and in part will be clear to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0019] Both the foregoing general description and the following detailed description present embodiments intended to provide an overview or framework for understanding the nature and character of the embodiments disclosed herein. The accompanying drawings are included to provide further understanding and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description explain the principles and operations thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a schematic view of an electroluminescent display utilizing a circular polarizer;

[0021] FIG. 2 is a schematic view of an electroluminescent display according to embodiments disclosed herein;

[0022] FIG. 3 is a top view of an exemplary pixel showing angled wedge-shaped features positioned overtop electroluminescent elements;

[0023] FIG. 4A is a cross-sectional side view of a portion of the electroluminescent display of FIG. 2 showing elements of a contrast enhancement layer;

[0024] FIG. 4B is a close-up cross-sectional view of a wedge-shaped feature depicted in FIG. 5A (without fill, for clarity);

[0025] FIG. 5 is a plot showing modeled cover plate transmittance as a function of feature width Wl;

[0026] FIG. 6 is a plot showing transmittance for varying wedge-shaped feature heights Hl as a function of LED emission angle;

[0027] FIG. 7 is a plot showing reflectance for varying wedge-shaped feature heights Hl as a function of angle of incidence;

[0028] FIG. 8 is a schematic diagram showing light emitted by an electroluminescent element intersecting a wedge-shaped feature, in accordance with embodiments disclosed herein;

[0029] FIG. 9 is a close-up view of a portion of FIG. 8;

[0030] FIG. 10 is a plot of modeled and normalized light intensity as a function of viewing angle (0v) for several values of An and compared to a Lambertian distribution;

[0031] FIG. 11 is a plot showing modeled transmittance between a cover plate comprising wedge-shaped features (WSF) 118 and a display device comprising a circular polarizer (CP);

[0032] FIG. 12 is a plot showing modeled reflectance between a cover plate comprising wedge-shaped features (WSF) 118 and a display device comprising a circular polarizer (CP);

[0033] FIG. 13 is a cross-sectional view of an ambient contrast fdter including an optional light absorbing layer positioned on an MRT base layer, e.g., between the MRT base layer and a substrate layer 112;

[0034] FIG. 14 is a plot of the natural log (In) of modeled transmittance at a wavelength of 550 nm as a function of thickness in micrometers for a light absorbing layer;

[0035] FIG. 15 is a plot of absorption at a wavelength of 550 nm as a function of thickness in micrometers for a light absorbing layer; [0036] FIG. 16 shows a theoretical prediction of optical transmittance (or absorption) of a thin absorbing layer 150 for layer thicknesses d (from 0.1 pm to 10 pm), and its extinction coefficient, k, as a function of transmittance T;

[0037] FIG. 17 is a plot of transmittance as a function of pitch Pl for various values of k and a wedge-shaped feature height Hl of 70 pm;

[0038] FIG. 18 is a graph of modeled reflectance as a function of pitch for various values of k and a wedge-shaped feature height Hl of 50 pm;

[0039] FIG. 19 is a graph of modeled reflectance as a function of pitch for various values of k and a wedge-shaped feature height Hl of 70 pm;

[0040] FIG. 20 shows modeled normalized intensity as a function of electroluminescent element emission angle with and without a light absorbing layer for a wedge-shaped feature height Hl of 50 pm;

[0041] FIG. 21 shows modeled normalized intensity as a function of electroluminescent element emission angle with and without a light absorbing layer for a wedge-shaped feature height Hl of 70 pm;

[0042] FIG. 22 is a graph showing modeled ambient contrast ratio of an ambient contrast filter as a function of total reflectance;

[0043] FIG. 23 is a cross-sectional view of a portion of an ambient contrast filter comprising a substrate layer and an ACE layer comprising pluralities of wedge-shaped features of different heights embedded therein;

[0044] FIG. 24 is a graph showing modeled transmittance as a function of pitch for an ambient contrast filter comprising wedge-shaped features of two different heights;

[0045] FIG. 25 is a graph showing modeled reflectance as a function of pitch for an ambient contrast filter comprising wedge-shaped features of two different heights,

[0046] FIG. 26 is a plot showing modeled transmittance data for a display device having two pluralities of wedge-shaped features of different heights as a function of the second height;

[0047] FIG. 1 is a plot showing modeled reflectance data for a display device having two pluralities of wedge-shaped features of different heights as a function of the second height;

[0048] FIG. 28 is a plot of modeled angular emission profiles for light emitted from an electroluminescent element of a display with a single (first) plurality of wedge-shaped features and a display with two (first and second) pluralities of wedge-shaped features;

[0049] FIG. 29 is a cross-sectional view of another electroluminescent display device according to the present disclosure comprising a backplane substrate including a plurality of electroluminescent elements deposited thereon and an ambient contrast fdter disposed over the backplane substrate, the ambient contrast filter lacking a glass substrate layer;

[0050] FIG. 30 is a side view of a first-step processing apparatus configured to produce an MRT film comprising an MRT base layer and a support layer;

[0051] FIG. 31 is a side view of a second-step processing apparatus for producing an ambient contrast filter using the MRT film produced by the apparatus of FIG. 30;

[0052] FIG. 32 is a side view of another processing apparatus for producing an ambient contrast filer in a continuous, inline process;

[0053] FIG. 33 is a cross-sectional side view of an exemplary display device according to embodiments of the present disclosure;

[0054] FIG. 34 is a cross-sectional side view of another exemplary display device according to embodiments of the present disclosure;

[0055] FIG. 35 is a cross-sectional side view of yet another exemplary display device according to embodiments of the present disclosure;

[0056] FIG. 36 is a cross-sectional side view of still another exemplary display device according to embodiments of the present disclosure; and

[0057] FIG. 37 is a plot showing measured optical transmission and ambient contrast ratio for ambient contrast filters on the display devices of FIGS. 33-36.

DETAILED DESCRIPTION

[0058] Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. However, this disclosure can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0059] As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art.

[0060] Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value to the other particular value. Similarly, when values are expressed as approximations by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0061] Directional terms as used herein — for example, up, down, right, left, front, back, top, bottom — are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0062] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus, specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0063] As used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0064] The word “exemplary,” “example,” or various forms thereof are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” or as an “example” should not be construed as preferred or advantageous over other aspects or designs. Furthermore, examples are provided solely for purposes of clarity and understanding and are not meant to limit or restrict the disclosed subject matter or relevant portions of this disclosure in any manner. It can be appreciated that a myriad of additional or alternate examples of varying scope could have been presented but have been omitted for purposes of brevity.

[0065] As used herein, the terms “comprising” and “including,” and variations thereof, shall be construed as synonymous and open-ended, unless otherwise indicated. A list of elements following the transitional phrases comprising or including is a non-exclusive list, such that elements in addition to those specifically recited in the list may also be present. [0066] The terms “substantial,” “substantially,” and variations thereof as used herein are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, “substantially” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially” may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0067] As used herein a circumferential surface of a roller is the outer surface of the roller extending around the circumference of the roller.

[0068] Electroluminescent displays may suffer from surface reflection leading to ambient contrast degradation. For example, FIG. 1 depicts a cross-sectional image showing a portion of a micro-LED display 10 comprising a backplane substrate 12 comprising a plurality of electroluminescent elements 14, e.g., LEDs, deposited thereon. The electroluminescent display 10 further comprises a cover plate 18. Cover plate 18 can include a phase retarding layer 20 and a linear polarizing layer 22, which together form circular polarizer 24. As shown in FIG. 1, ambient light rays 26 enter display 10 through coverplate 18, are incident on first surface 28 of backplane substrate 12 at an incidence angle 9inc relative to a normal to first surface 28 and are reflected from backplane substrate 12 at a reflection angle 0_ref represented by light ray 30. The plurality of electroluminescent elements 14 also generate and emit light represented by light ray 32. The emitted light 32 can be transmitted through the cover plate 18 in a direction toward external viewer 34 as an image Reflected ambient light 30 competes with emitted light 32, which can result in the displayed image having reduced contrast as viewed by viewer 34. As such, display 10, or a portion thereof, can appear washed-out to the viewer.

[0069] To avoid ambient contrast degradation, a contrast-enhancing layer is provided for electroluminescent display applications including light emitting diode (LED) displays, organic light emitting diode (OLED) displays, or quantum dot displays, but which contrast-enhancing layer is particularly useful for micro-LED displays. The contrast-enhancing layer can comprise a micro-replicated contrast enhancement film configured to repress reflected ambient light from competing with light emitted by the electroluminescent elements. The electroluminescent display can have pixel sizes on the order of a few tens of micrometers to hundreds of micrometers. For example, an electroluminescent display may comprise red (R), green (G), and blue (B) LEDs, with each set of red, green, and blue LEDs forming a pixel. The size of a micro-LED (e.g., a dimension along one side of the LED) can range from about 10 pm to about 1000 pm. For example, LED chips can be sized with an area in a range of about 10 pm² to about 1000 pm². In such embodiments, the size of the light emitting area of each LED chip can be less than about 20% of the pixel area.

[0070] The contrast-enhancing layer can comprise elements for reducing or eliminating ambient light reflection from the pixels or components thereof. As disclosed herein, these elements can comprise a plurality of light absorbing wedge-shaped features, e.g., trapezoidalshaped features, arranged in rows. The wedge-shaped features can be numerically evaluated and optimized to reduce or eliminate ambient light reflected by the pixel electroluminescent elements (e.g., individual LEDs).

[0071] FIG. 2 is a cross-sectional view of an exemplary electroluminescent display device 100 according to the present disclosure comprising a backplane substrate 102 including a plurality of electroluminescent elements 104 deposited thereon and an ambient contrast filter 106. Electroluminescent elements 104 may comprise individual pixel elements of an image pixel, and may, accordingly, be configured to display different colors, for example red (R), green (G), and blue (B). Ambient contrast filter 106 can be spaced apart from backplane substrate 102 by an air gap 110. Air gap 110 can be in a range from about 50 pm to about 5 mm, for example in a range from about 100 pm to about 5 mm, such as in a range from about 200 pm to about 4 mm, in a range from about 300 pm to about 3 mm, or in a range from about 1 mm to about 3 mm, including all ranges and subranges therebetween.

[0072] Ambient contrast filter 106 may include a substrate layer 112, an ambient contrast enhancement (ACE) layer 114, and optionally an anti-reflection (AR) layer 116. Substrate layer 112 may comprise a glass material, for example a silicate glass material such as an aluminosilicate glass material, although substrate layer 112 may comprise a polymer material. AR layer 116 may be joined to substrate layer 112 by an adhesive layer 122, for example a pressure-sensitive adhesive.

[0073] ACE layer 114 comprises a first plurality of light absorbing features, e.g., wedge- shaped features 118 disposed in a micro-replicated thin film (MRT film 120). MRT film 120, in turn, comprises an MRT base layer 124 disposed on a support layer 125. Support layer 125 can comprise a polymer material, for example polyethylene terephthalate (PET). Wedge- shaped features 118 are separated within MRT base layer 124 by light transmissive regions 126.

[0074] First plurality of light absorbing wedge-shaped features 118 may comprise any suitable material that can absorb or block light at least in a portion of the visible spectrum. For example, the light absorbing features may include a black colorant, e.g., a black particulate such as carbon black. The carbon black can comprise a particle size equal to or less than about 500 nm, for example in a range from about 10 nm to about 500 nm, in a range from about 10 nm to about 400 nm, in a range from about 10 nm to about 300 nm, or in a range from about 10 nm to about 200 nm, including all ranges and subranges therebetween. However, the light absorbing material can include a colorant having other colors such as white, red, green, or yellow. The light absorbing material, (e.g., carbon black, a pigment or dye, or combinations thereof) can be dispersed in a suitable matrix material, e.g., a polymer resin.

[0075] FIG. 3 is a top view of a portion (e.g., a single pixel) of an electroluminescent display viewed from the viewer side of the display showing first plurality of elongate wedge-shaped features 118 arranged in parallel rows, each wedge-shaped feature of the first plurality of wedge-shaped features comprising a longitudinal axis 136. As shown, the wedge-shaped features 118 are elongate structures located between the electroluminescent elements and the viewer. As further shown, the first plurality of wedge-shaped features 118 may not be aligned with an alignment axis 138 of a row of electroluminescent elements 104, but instead can be angled across the electroluminescent elements by an angle a relative to alignment axis 138. Angle c can be in a range from about 0 to about 10 degrees, for example in a range from greater than 0 degrees to about 10 degrees.

[0076] Conditions for a design of ACE layer 114 can be identified by parametric studies on structural variations and the refractive index of the wedge-shaped features. For example, in some embodiments, a maximum width W 1 of individual wedge-shaped features of the first plurality of wedge-shaped features, taken at a base 140 of the wedge-shaped features, can be less than one half the length L(pixel) of a display pixel (L(pixel)/2) for a transmittance T greater than 50%. Transmittance is the ratio of transmitted light power through a given geometry to injected light power along the normal direction. For example, the maximum width W1 of a wedge-shaped feature 118 can be in a range from about 10 pm to about 100 pm. For some specific backplane substrate designs (e g., LED chip size: 38x54 pm², L(pixel) = 432 pm, D(chip-to-chip) = 100 pm), W 1 can be in a range from about 5 pm to about 25 pm, for example in a range from about 5 pm to about 20 pm, such as in a range from about 5 pm to about 15 pm. L(pixel) can be in a range from about 10 pm to about 1000 pm.

[0077] FIGS. 4A and 4B illustrate a portion of ambient contrast filter 106 showing dimensional parameters of wedge-shaped features 118. Each wedge-shaped feature 118 ofthe first plurality of wedge-shaped features may comprise a maximum width W 1 taken at base 140 of the feature (see FIG. 4B, fill omitted for clarity), a height Hl taken from base 140 to the opposing end 142 of the wedge-shaped feature, a pitch Pl taken as the distance from the center of one wedge-shaped feature 118 to the center of an immediately-adjacent wedge-shaped feature 118, and a wedge angle p evaluated between base 140 of a wedge-shaped feature 118 and an adjacent side 144 of the wedge-shaped feature.

[0078] In some embodiments, wedge angle can be in a range from about 70 degrees to less than 90 degrees, for example in a range from about 75 degrees to less than 90 degrees, such as in a range from about 80 degrees to less than 90 degrees, or in a range from about 85 degrees to less than 90 degrees. As such, maximum width W1 at base 140 is greater than the narrower width at opposing end 142. In other words, the wedge-shaped feature can comprise a trapezoidal cross-sectional shape with opposing end 142 projecting from base 140 toward the plurality of electroluminescent elements 104. This arrangement can improve ambient light reduction while simultaneously providing a larger viewing angle for the electroluminescent display. The viewing angle is an angle at which the brightness of the electroluminescent display to a viewer is one half the brightness evaluated along a normal to the electroluminescent display (e.g., a normal to the cover plate).

[0079] FIG. 5 is a graph showing modeled ambient contrast filter transmittance as a function of feature width Wl. The data show that as wedge-shaped feature width W1 decreases, transmittance increases.

[0080] FIGS. 6 and 7 show, respectively, transmittance and reflectance for varying wedge- shaped feature heights Hl as a function of LED emission angle (FIG. 6) and angle of incidence (FIG. 7). The data shown in FIG. 6 show that as wedge-shaped feature height Hl decreases, transmittance desirably increases. Conversely, the data shown in FIG. 7 indicate that as wedge- shaped feature height Hl decreases, reflectance undesirably increases. As the emission angle of an electroluminescent element increases, transmittance decreases. As the angle of incidence of the ambient light increases, reflectance decreases until an angle of incidence of about 60° is reached, then there is divergent behavior between large height (greater than about 50 pm) and small heights (less than about 50 pm, e.g., 20 pm). For heights Hl of 20 pm and 10 pm and an angle of incidence greater than about 60°, reflectance increases, but decreases for heights of in a range from about 50 pm to about 150 pm. Thus, wedge-shaped feature height can involve a trade-off between transmittance and reflectance to find an optimum height Hl for a particular display device configuration. [0081] Height Hl can be in a range from about 10 jam to about 100 jam, for example in a range from about 10 pm to about 80 pm, in a range from about 10 pm to about 60 pm, such as in a range from about 10 pm to about 40 pm. The height-to-width aspect ratio Hl/Wl of a wedge-shaped feature 118 can be equal to or greater than about 2, for example equal to or greater than about 3. For example, the aspect ratio Hl/Wl can be in a range from about 2 to about 6, or from about 3 to about 5, or less than about 5, or less than about 4.

[0082] Pitch Pl of the wedge-shaped features 118 can be in a range from about 5 pm to about 500 pm, for example from about 5 pm to about 200 pm, such as in a range from about 5 pm to about 100 pm, from about 5 pm to about 60 pm, or in a range from about 5 pm to about 40 pm, including all ranges and subranges therebetween.

[0083] Additionally, each wedge-shaped feature 118 can comprise an index of refraction rm. and MRT base layer 124 can comprise an index of refraction m. The refractive index rm of the wedge-shaped features 118 can be selected to improve the viewing angle of the display. For example, FIG. 8 is a schematic diagram showing two adjacent wedge-shaped features and a light ray 32 emitted by an electroluminescent element 104 intersecting side surface 146 of a wedge-shaped feature 118 at an angle 0B relative to a normal 148 to the intersected surface. FIG. 9 is a close-up view illustrating when 0B is equal to or greater than 0_C, the critical angle at which total reflection occurs (0c = arcsin np/ni ). A difference An between the index of refraction of the wedge-shaped feature 118, nB, and the refractive index of the surrounding MRT base layer 124, nF, i.e., An = nB - m. can create large reflectance values at high incidence angles due to total internal reflection, e.g., 0B > 0c, as shown in the modeled data of FIG. 10. FIG. 10 is a plot of modeled and normalized light intensity as a function of viewing angle (0v) for several values of An and compared to a Lambertian distribution. The arrangement of the plurality of wedge-shaped features 118 into parallel rows, the wedge angle between the base of a wedge-shaped feature and an adjacent side of the wedge-shaped feature, the height to width (H/W) aspect ratio, and the trapezoidal cross-sectional shape having a base and an opposing top projecting toward the plurality of electroluminescent elements, all contribute to the improvements observed in transmittance and viewing angle. The data show viewing angle may be improved (increased) by selecting a material for the wedge-shaped features with an index of refraction nB less than the index of refraction nF for MRT base layer 124 surrounding the wedge-shaped feature 118. For example, the viewing angle may be improved to greater than 30 degrees, or greaterthan 40 degrees, or greater than 45 degrees. MRT base layer 124 and/or wedge-shaped features 118 can be selected to provide a An in a range from about -0.5 to about 0, for example in a range from about -0.3 to 0.

[0084] FIGS. 11 and 12 show, respectively, modeled transmittance and reflectance between a coverplate comprising wedge-shaped features (WSF) 118 and a display device comprising a circular polarizer (CP). The data in FIG. 11 predict an approximately 22% increase in transmittance for the ambient contrast fdter using wedge-shaped features as described herein. FIG. 12 shows that, for an incoming ambient light ray with an incidence angle of 0° and 50°, while the amount of ambient reflected light can be greater for the wedge-shaped feature display, the circular polarizer-equipped display demonstrates a significant increase in reflected light at an incidence angle 0_mc of 50° compared to the WSF display at the same incidence angle. The improved optical transmittance of the WSF ambient contrast filter can utilize a lower injection of electrical current into the electroluminescent elements (e.g., micro-LEDs) to obtain the same brightness as the circularly polarizing cover plate. This provides additional benefits for the display device (e.g., micro-LED display), including, for example, longer display lifetime and reliability. In some embodiments, the optical transmittance of an ambient contrast filter can be at least 50%, for example at least 60%, at least 70%, at least 80%, or at least 90%.

[0085] Turning now to FIG. 13, ACE filter layer 114 may comprise an optional absorbing layer 150 positioned on MRT base layer 124, e.g., between MRT base layer 124 and substrate layer 112. Light absorbing layer 150 can be formed from the same or similar material as wedge-shaped features 118. Accordingly, the transmittance of light absorbing layer 150 may be controlled by controlling a density of the light absorbing material disposed in light absorbing layer 150 and/or a thickness 151 of light absorbing layer 150 to obtain a predetermined transmittance. For example, light absorbing layer 150 can contain carbon particles (e.g., carbon black) or other suitable particles with a density in a range from about 1% by weight to about 20% by weight, for example in a range from about 5% by weight to about 15% by weight, in a range from about 5% by weight to about 10% by weight, in a range from about 5% by weight to about 9% by weight, or in a range from about 6% by weight to about 8% by weight. The percentage of carbon black can be about 7.5 percent by weight. The material comprising light absorbing layer 150 may be the same material comprising wedge-shaped features 118. Thickness 151 of light absorbing layer 150 can be in a range from about 10 nm to about 1 micrometer, for example in a range from about 0.1 pm to about 10 pm. As described in more detail below, particle density and/or thickness of light absorbing layer 150 may be used to obtain a transmittance of at least about 60% through light absorbing layer 150. [0086] FIG. 14 is a plot of the natural log (In) of modeled transmittance at a wavelength of 550 nm as a function of thickness in micrometers for a light absorbing layer 150. The plot of FIG. 14 depicts a linear fit to the data. The plot shows a decrease in transmittance can be obtained by increasing the thickness of the light absorbing layer 150. FIG. 15 is a plot of absorption of the light absorbing layer 150 at a wavelength of 550 nm, again as a function of thickness in micrometers. The plot of FIG. 15 shows an increase in absorption as the thickness of the light absorbing layer increases. This leads to a reduction in surface reflection and, as a result, the ambient contrast ratio of an ambient contrast filter including a layer of light absorbing material is improved over embodiments without a light absorbing layer. While light absorbing layer 150 may result in a small transmittance reduction for ambient contrast filter 106 compared to an ambient contrast filter with wedge-shaped features 118 but no light absorbing layer 150, the result of including a light absorbing layer 150 can be an increased contrast ratio. For example, a contrast ratio equal to or greater than about 500 may be attained by including both wedge-shaped features 118 and light absorbing layer 150.

[0087] An extinction coefficient k of light absorbing layer 150 may be selected to match a target transmittance, for example, a transmittance equal to or greater than 60%. The extinction coefficient k is the imaginary component of the complex refractive index (n + ik) and can be varied by selecting particle density and or thickness of light absorbing layer 150, which can determine absorption level. The extinction coefficient k can be calculated from the following equation, T = c^/ (4nk/X)d. where T represents transmittance, d represents the thickness of the film, and n is refractive index (^A indicates exponent). FIG. 16 shows a theoretical prediction of optical transmittance (or absorption) of a thin absorbing layer 150 for layer thicknesses d (from 0.1 pm to 10 pm), and its extinction coefficient, k, as a function of transmittance T (equal to 1- A, where A represents absorbance).

[0088] The performance impact of light absorbing layer 150 was numerically evaluated by ray-optic simulation, the results of which analysis are shown in FIGS. 17-19. The pitch Pl (spatial period) of wedge-shaped features 118 was one of the geometric parameters studied, together with k. For this analysis, it was assumed reflectance at backplane substrate 102 was 10% of the incident ambient light. The target transmittance and reflectance of the ambient contrast filter was 60% and 70%, respectively. FIG. 17 is a plot of transmittance as a function of pitch Pl for various values of k and a wedge-shaped feature height Hl of 70 pm. The data show that as k increases (light absorbing layer 150 becomes more absorptive), for example greater than 0.05, transmittance decreases (since reflectance is inversely proportional to ambient contrast ratio (ACR), optical transmittance and ACR are in an opposing relationship). ACR is calculated as l+I_o/(Iamb-Ramb), where I_o is an intensity of light emitted by the electroluminescent element in an “on” state, Iamb is the intensity of the ambient light, and Ramb is the reflectance of the ambient light from backplane substrate 102. To satisfy both transmittance and reflectance needs, k can be selected to be in a range from about 0.05 to about 1. The choice of k can also depend on the thickness of light absorbing layer 150.

[0089] In addition, the height Hl of wedge-shaped features 118 was evaluated over a range from about 50 pm to about 70 pm. FIG. 18 is a graph of modeled reflectance as a function of pitch for various values of k and a wedge-shaped feature height Hl of 50 pm, and FIG. 19 is a graph of modeled reflectance as a function of pitch for various values of k and a wedge-shaped feature height Hl of 70 pm. The data show that as k increases, reflectance decreases, but conversely, as pitch increases reflectance increases. Testing has shown that reducing the height Hl of the wedge-shaped features can make both patterning of recesses defining the geometry of the wedge-shaped features and processes for filling those recesses with a light absorbing material more reliable. These behaviors may be used to find an appropriate trade-off between pitch, wedge-shaped feature height, and k that minimizes reflectance. Interestingly, the data for a large value of k, in both simulations, e.g., k = 0.5, shows a low reflectance sensitivity for both pitch and height, a trend evident in the lesser values of k. That is, the data show that at high values of k, reflectance varies little as a consequence of changes in wedge-shaped feature pitch and height.

[0090] Angular emission profiles of LED light emited from a display (e g., from ambient contrast filter 106) in the presence of light absorbing layer 150 was also analyzed, since the emission profile can help determine electroluminescent display viewing angle. The cases of Hl = 50 pm (FIG. 18) and 70 pm (FIGS. 17 and 19) were again evaluated and compared to a ambient contrast filter without light absorbing layer 150. FIGS. 20 and 21 present modeled and normalized intensity as a function of electroluminescent element emission angle. This analysis confirmed the presence of light absorbing layer 150 in addition to wedge-shaped features 118 can provide increased viewing angle compared to an ambient contrast filter without light absorbing layer 150. The data show that an ambient contrast filter comprising both wedge-shaped features 118 and light absorbing layer 150, exhibiting an extinction ratio in a range from about 0.01 to about 0.1, can provide an ACR in excess of 500 in micro-LED displays. [0091] FIG. 22 is a graph showing modeled ambient contrast ratio as a function of total reflectance. The data present a prediction of ambient contrast ratio (ACR) under different levels of ambient illumination, in nits, and the achievable ACR. For example, axis 153 represents a display device comprising a plurality of wedge-shaped features and a light absorbing layer 150 as disclosed herein, whereas axis 155 represents the same display with wedge-shaped features 118 but without light absorbing layer 150. As a comparison, axis 157 represents the same display without wedge-shaped features 118 and without light absorbing layer 150. The amount of ambient light reflectance from the backplane substrate was assumed to be 10% The data show that an ACR greater than 500 is achievable by a display device having an ambient contrast filter with both light absorbing wedge-shaped features 118 combined with light absorbing layer 150.

[0092] Shown in FIG. 23 is still another embodiment of an ambient contrast filter 106, wherein the ambient contrast filter can comprise alternating rows of wedge-shaped features of differing heights and differing widths. FIG. 23 depicts a cross-sectional view of a portion of ambient contrast filter 106 comprising substrate layer 112 and ACE layer 114 comprising pluralities of wedge-shaped features embedded therein, the first plurality of wedge-shaped features 118 and a second plurality of wedge-shaped features 160. The first plurality of wedge- shaped features 118 can be arranged as rows of elongate wedge-shaped features with maximum width W1 and a height Hl as previously described. The second plurality of wedge-shaped features 160 can also be arranged as parallel rows of elongate wedge-shaped features with a maximum width W2 at the base of the wedge-shaped features 160 and a height H2, where the height H2 is evaluated from the base of wedge-shaped features 160 to the opposing end (the end farthest from substrate layer 112) in the same manner as wedge-shaped features 118. The second plurality of wedge-shaped features 160 may be arranged in an alternating arrangement with the first plurality of wedge-shaped features 118. Height H2 of wedge-shaped features 160 of the second plurality of wedge-shaped features may be less than the height Hl of wedge- shaped features 118 of the first plurality of wedge-shaped features. The maximum width W2 of wedge-shaped features 160 of the second plurality of wedge-shaped features may be less than the maximum width W1 of wedge-shaped features 118 of the first plurality of wedge- shaped features. Accordingly, both height H2 and maximum width W2 may be less than the height Hl and the maximum width W1 of wedge-shaped features 118 of the first plurality of wedge-shaped features, respectively. An aspect ratio defined as Hl/Wl may be equal to or greater than about 3, for example, in a range from about 3 to about 6. [0093] Referring still to FIG. 23, the first plurality of wedge-shaped features 118 may be periodically spaced with a pitch P 1 defining a separation distance between the adjacent wedge- shaped features as measured from a center one of wedge-shaped feature 118 to the center of the adjacent wedge-shaped feature 118. Pitch Pl of the first plurality of wedge-shaped features may be in a range from about 50 pm to about 200 pm, for example in a range from about 60 pm to about 150 pm, from about 60 pm to about 100 pm, or in a range from about 60 pm to about 90 pm. Additionally, wedge-shaped features 160 may also be periodically spaced, with a pitch P2 defining a separation distance between adjacent wedge-shaped features 160 as measured from a center of one wedge-shaped feature 160 to the center of another, adjacent, wedge-shaped feature 160. Each wedge-shaped feature 160 may be positioned half-way between adjacent wedge-shaped features 118 such that P2 is equal to P 1. That is, the second plurality of wedge-shaped features 160 can be equally spaced between the first plurality of wedge-shaped features 118. Thus, a distance between the center of a wedge-shaped feature 118 and an adjacent wedge-shaped feature 160 can be (Pl)/2.

[0094] FIGS. 24 and 25 present modeled data showing transmittance (FIG. 24) and reflectance (FIG. 25) as a function of pitch Pl and assuming P2 = Pl. The data show a comparison of a display with a single plurality of wedge-shaped features compared to a display with two pluralities of wedge-shaped features, wherein a height of the second plurality of wedge-shaped features is different than a height of the first plurality of wedge-shaped features. The data further show that a display with two pluralities of wedge-shaped features of two different heights, respectively, and with a larger pitch P 1 (e.g., 90 pm) can have similar optical performance as a display with a single plurality of wedge-shaped features of the same height and a short pitch (e.g., 60 pm) while maintaining a transmittance over 60% and a reflectance below 8%. Although the addition of the second plurality of wedge-shaped features can make the overall pattern of wedge-shaped features denser when viewed from a viewer’s perspective, the additional plurality of wedge-shaped features with a low aspect ratio does not significantly deteriorate viewing angle for a human observer and can provide an absorptive geometry that helps ambient light rejection.

[0095] FIGS. 26 and 27 present modeled data for a display having two pluralities of wedge- shaped features of different heights and show transmittance (FIG. 26) and reflectance (FIG. 27) as a function of height H2. With H2 ranging from 10 pm to 70 pm, the result is different from the trend observed with pitch variation. However, the impact of H2 is not so considerable, giving a change in transmittance less than 10% and a change in reflectance less than 1% under the assumption that the light absorbing material is highly absorption, e.g., comprises an extinction coefficient k greater than 0.1.

[0096] The data show that a greater height H2 gives rise to greater transmittance and a lower reflectance. Transmittance increases according to a greater height H2 because surface area inducing total internal reflection widens. However, reflectance decreases due to an increased aspect ratio of the second plurality of wedge-shaped features.

[0097] FIG. 28 is a plot of modeled angular emission profiles for light emitted from an electroluminescent element with a single (first) plurality of wedge-shaped features and a display with two (first and second) pluralities of wedge-shaped features. The plot of FIG. 28 shows light intensity as a function of viewing angle for the emitted light. In this comparison, the display with a single plurality of wedge-shaped features and the display with two pluralities of wedge-shaped features have pitches (Pl, P2) of 60 pm and 90 pm, respectively. The data show a display with two pluralities of wedge-shaped features with different aspect ratios can have an improved viewing angle compared to a display with a single plurality of wedge-shaped features, without sacrificing basic optical performance.

[0098] Ambient contrast filter 106 may be employed without a glass substrate layer 112. For example, FIG. 29 is a cross-sectional view of another exemplary electroluminescent display device 100 according to the present disclosure comprising a backplane substrate 102 including a plurality of electroluminescent elements 104 deposited thereon and an ambient contrast filter 106 disposed over backplane substrate 102. Electroluminescent elements 104 comprises individual pixel elements of an image pixel, and may, accordingly, be configured to display different colors, for example red (R), green (G), and blue (B). However, in the embodiment of FIG. 29, ambient contrast filter 106 lacks a substrate layer 112, e.g., a glass substrate layer. Thus, in various embodiments, ambient contrast filter 106 can be formed by ACE layer 114 comprising support layer 125, MRTbase layer 124, wedge-shaped features 118 (and optionally wedge-shaped features 160) and light absorbing layer 150. ACE layer 114 can be attached directly to backplane substrate 102 directly and/or to electroluminescent elements 104, by an adhesive layer 122, and therefore without an air gap between the electroluminescent elements 104 and ambient contrast filter 106. Adhesive layer 122 can be, for example, an optically clear adhesive. Ambient contrast filter 106 can include at least one AR layer 116, for example an AR layer 116 disposed overtop light absorbing layer 150.

[0099] Advantageously, an ambient contrast filter that does not include a glass substrate layer can be applied directly to the electroluminescent display panel, e.g., backplane substrate 102, allowing the display device to be considerably thinner than embodiments utilizing a glass substrate layer. Moreover, display panels that include a glass substrate layer are typically manufactured by forming multiple display panels on a single backplane “motherboard,” and attaching a cover plate including a glass substrate layer to the backplane before dicing the motherboard into individual display panels. This requires cutting not only the backplane but the glass substrate layer as well, thereby increasing cutting difficulty and adding to display panel cost. Elimination of the glass substrate layer can make cutting display panels from larger display motherboards easier and less costly. Additionally, elimination of the glass substrate layer can reduce transportation and installation costs. Display panels utilizing a film-type ambient contrast filter without a glass substrate layer are easier to handle due to their small size and light weight. For film-type solutions, the manufacturing can be done in a roll-to-roll process, from patterning the MRT base layer to filling recesses with light absorbing material to low reflection patterning, processes suitable for large volume production

[0100] Accordingly, an apparatus 200 for forming ambient contrast filter 106 is shown in FIGS. 30-31. Turning first to FIG. 30, apparatus 200 may include a first-step processing apparatus 202 configured to produce MRT film 120 comprising MRT base layer 124 and support layer 125. First-step processing apparatus 202 comprises patterning roller 204, first support roller 206, second support roller 208, first dispensing nozzle 210, and first curing apparatus 212. Patterning roller 204 is an elongate roller with a generally circular cross section comprising a plurality of protrusions 214 (e.g., teeth) disposed about a first circumferential surface 216 of the patterning roller and extending along the length of the patterning roller, the protrusions 214 corresponding to wedge-shaped features 118. The plurality of protrusions 214 may be periodically spaced. For example, each protrusion 214 can be spaced from an adjacent protrusion around first circumferential surface 216 an equal distance such that the angular distance between each protrusion is equally divided. For purposes of description and not limitation, if patterning roller 204 has 60 protrusions, the 60 protrusions can be angularly spaced every 1° about the circumferential surface of the patterning roller. If patterning roller 204 has 120 protrusions, the 120 protrusions can be spaced every 0.5°. Of course, it should be recognized that in practical applications, spacing between protrusions are on the order of micrometers, e.g., equivalent to produce the period Pl desired for the wedge-shaped features 118. That is, appropriate to produce a period for wedge-shaped features 118 and/or 160 in a range from about 40 pm to about 500 pm, for example from about 50 pm to about 200 pm, such as in a range from about 60 pm to about 150 pm, from about 60 pm to about 100 pm, or in a range from about 60 pm to about 90 pm, including all ranges and subranges therebetween. [0101] However, protrusions 108 can be differently spaced such that the angular distance between one pair of adjacent protrusions is different than the angular distance between another pair of adjacent protrusions. For example, the angular distance can increase from one pair of adjacent protrusions to the next pair of adjacent protrusions relative to a predetermined direction of rotation about the patterning roller. Again, by way of example and not limitation, consider four sequentially arranged protrusions, a first protrusion, a second protrusion adjacent the first protrusion, a third protrusion adjacent the second protrusion, and a fourth protrusion adjacent the third protrusion. An angular distance between the first protrusion and the adjacent second protrusion can be 1°, for example going in a clockwise direction. An angular distance between the second protrusion and the third protrusion can be 1.01°. An angular distance between the third protrusion and the fourth protrusion can be 1.02°, and so on, each protrusion angularly spaced from the preceding protrusion by an additional 0.01°. Of course, the angular distance between adjacent protrusions returns to 1° when one again reaches the first and second protrusions. It should be apparent that patterning roller 204 can comprise sub-patterns of protrusions, wherein the repetition upon return to the first protrusion occurs, for example, every 10 protrusions Indeed, one may provide the protrusions in any predetermined pattern including any angular or circumferential distance between protrusions as desired or needed to produce a similar pattern of wedge-shaped features.

[0102] Patterning roller 204 comprises and is rotatable about first axis of rotation 218. Protrusions 214 can extend along a length of patterning roller parallel with each other. For example, each protrusion can be an elongate structure extending above first circumferential surface 216 by height Hl. Protrusions 214 may be parallel with first axis of rotation 218, but alternatively, protrusions 214 may be arranged helically about first axis of rotation 218 on first circumferential surface 216. In some embodiments, a height of protrusions 214 relative to first circumferential surface 216 along a line normal to first circumferential surface 216 may vary. For example, as previously described, two different heights, Hl and H2, may be provided, corresponding to the heights of wedge-shaped features 118 and 160, respectively, although additional numbers of heights, e.g., greater than two heights, corresponding to further pluralities of wedge-shaped features, may be provided.

[0103] First support roller 206 comprises a second circumferential surface 220 disposed around and rotatable about second axis of rotation 222. Second circumferential surface 220 can be a smooth surface. Second axis of rotation 222 may be parallel with first axis of rotation 218. Second circumferential surface 220 may be spaced from first circumferential surface 216 by a first predetermined distance 224. That is, first circumferential surface 216 may be separated from second circumferential surface 220 by a first gap 226. First predetermined distance 224 is greater than a maximum height of protrusions 214, e.g., greater than Hl.

[0104] Second support roller 208 comprises a third circumferential surface 228 disposed around and rotatable about a third axis of rotation 230. Like first support roller 206, third circumferential surface 228 can be a smooth surface . Third axis of rotation 230 may be parallel with first axis of rotation 218. Third circumferential surface 228 may be spaced from first circumferential surface 216 by a second predetermined distance 232. That is, first circumferential surface 216 is separated from third circumferential surface 228 by a second gap 234. Second predetermined distance 232 is greater than a maximum height of protrusions 214, e.g., greater than Hl. First axis of rotation 218, second axis of rotation 222, and third axis of rotation 230 may be coplanar, i.e., lie in the same plane.

[0105] First dispensing nozzle 210 is configured to dispense a matrix material 236 into first gap 226 between patterning roller 204 and first support roller 206. Additionally, first curing apparatus 212 is configured to cure matrix material 236 to form MRT base layer 124. First curing apparatus 212 comprises a curing device 238, for example a UV lighting device, configured to direct a first UV light 240 into first gap 226.

[0106] As depicted in FIG. 30, support layer 125, such as a pre-formed polymer film e.g., PET, is guided into first-step processing apparatus 202 over first support roller 206 and directed into first gap 226. Support layer 125 compnses a first major surface 242 and a second major surface 244 opposite first major surface 242. With second major surface 244 of support layer 125 in contact with and supported by second circumferential surface 220 of first support roller 206, matrix material 236 is dispensed into first gap 226 in liquid form by first dispensing nozzle 210 from above first gap 226 and is deposited between first major surface 242 of support layer 125 and first circumferential surface 216 of patterning roller 204. Matrix material 236 may be, for example, a polymer resin, e.g., a UV-curable acrylate monomer, multifunctional acrylate oligomer, photoinitiator, and any additional additives as needed. A radical-type polymerization photoinitiator for base resin can be, for example, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, alpha-hydroxyphenylketone, 2,2-dimethoxy-2-phenyl-acetophenone, triarylphosphine oxide, or bisacylphosphine oxide.

[0107] A viscosity of matrix material 236 as the matrix material is dispensed from first dispensing nozzle 210 can be in a range from about 50 millipascal seconds (mPa-s) to about 1000 mPa-s, for example in a range from about 75 mPa-s to about 300 mPa-s. Protrusions 214 displace matrix material 236 in first gap 226 as patterning roller 204 and first support roller 206 rotate. For example, in the embodiment depicted in FIG. 30, the process runs from right to left, wherein patterning roller 204 is shown rotating in a clockwise direction and first support roller 206 is rotating in a counterclockwise direction. As the liquid matrix material 236 leaves first gap 226 adhered to first major surface 242 of support layer 125, the matrix material is cured by first curing apparatus 212 positioned below first gap 226 and/or patterning roller 204. For example, matrix material 236 may be an ultraviolet (UV) light-curable polymer material. Accordingly, first UV lighting device 238 emits first UV light 240 upward into first gap 226 and/or the underside of patterning roller 204 and through support layer 125, thereby curing matrix material 236 into MRT film 120 including support layer 125 and MRT base layer 124, MRT film 120 comprising a plurality of recesses 246 that mimic protrusions 214. That is, recesses 246 are the negative of protrusions 214. A refractive index of the cured MRT base layer 124 may be in a range from about 1.45 to about 1.65.

[0108] As further illustrated in FIG. 30, as patterning roller 204 rotates in the clockwise direction, MRT film 120 travels around and under first circumferential surface 216, with protrusions 214 engaged in recesses 246. MRT film 120 then wraps over second support roller 208 such that second major surface 244 of support layer 125 is in contact with third circumferential surface 228 of second support roller 208 and recesses 246 face outward, away from third circumferential surface 228. While not shown, MRT film 120 may be collected downstream of second support roller 208, rolled, and stored for later use or provided to a second apparatus that performs a second process step.

[0109] Accordingly, referring now to FIG. 31, apparatus 200 may further comprise a second- step processing apparatus 250. Second-step processing apparatus 250 includes application roller 302, third support roller 304, fourth support roller 306, second dispensing nozzle 308, second curing apparatus 310, and optionally a third curing apparatus 312.

[0110] Application roller 302 comprises a fourth circumferential surface 314 disposed and rotatable about fourth axis of rotation 316. Unlike patterning roller 204, fourth circumferential surface 314 can be a smooth surface.

[oni] Third support roller 304 comprises a fifth circumferential surface 318 disposed and rotatable about a fifth axis of rotation 320. Fifth circumferential surface 318 can be a smooth surface. In embodiments, fifth axis of rotation 320 is parallel with fourth axis of rotation 316. Fifth circumferential surface 318 can be spaced from fourth circumferential surface 314 by a third predetermined distance 322. That is, fourth circumferential surface 314 is separated from fifth circumferential surface 318 by a third gap 324. [0112] Fourth support roller 306 comprises a sixth circumferential surface 326 disposed and rotatable about sixth axis of rotation 328. Sixth circumferential surface 326 can be a smooth surface. In embodiments, sixth axis of rotation 328 is parallel with fourth axis of rotation 316. Sixth circumferential surface 326 can be spaced from fourth circumferential surface 314 by a fourth predetermined distance 330. That is, sixth circumferential surface 326 is separated from fourth circumferential surface 314 by a fourth gap 332.

[0113] As depicted in FIG. 31, MRT film 120 is guided into third gap 324 by third support roller 304, wherein MRT film 120 is captured in third gap 324 between third support roller 304 and application roller 302 (note that support layer 125 is not separately shown in FIG. W but is nonetheless included). For example, in the embodiment depicted in FIG. 32, the process runs from right to left, wherein application roller 302 rotates in a clockwise direction and third support roller 304 rotates in a counterclockwise direction. MRT film 120 advances over third support roller 304 with recesses 246 facing outward, away from fifth circumferential surface 318, and enters third gap 324. As MRT film 120 enters third gap 324 between application roller 302 and third support roller 304, recesses 246 are facing fourth circumferential surface 314 of application roller 302. Light absorbing material 334 is dispensed by second dispensing nozzle 308 into third gap 324 between application roller 302 and MRT film 120 and forced into recesses 246 by application roller 302. Light absorbing material 334 may be, for example, a polymer material comprising a light absorbing additive such as carbon black, wherein the carbon black is dispersed in the polymer material. A particle size of the carbon black particles can be in a range from about 10 nanometers (nm) to about 500 nm, for example in a range from about 10 nm to about 400 nm, such as in a range from about 10 nm to about 300 nanometers, or in a range from about 10 nm to about 200 nm. The carbon black particles may be present in the light absorbing material in an amount in a range from about 5 weight percent to about 10 weight percent, for example in a range from about 6 weight percent to about 8 weight percent. In some embodiments, the carbon black particles may be present in the light absorbing material in an amount of 7.5 weight percent. A viscosity of the light absorbing material dispensed from second dispensing nozzle 308 can be in a range from about 75 mPa- to about 300 mPa s.

[0114] Light absorbing material 334 is at least partially cured by second curing apparatus 310, thereby forming ACE layer 114. For example, light absorbing material 334 may be an ultraviolet (UV) light-curable polymer material. Accordingly, second curing apparatus 310 may comprise a UV light source 338 positioned below third gap 324 and/or application roller 302 and arranged to direct a second UV light 340 into third gap 324 and/or toward ACE layer 114 on application roller 302. Because the first curing of light absorbing material 334 is performed through the back side of MRT film 120 (the side opposite recesses 246), curing may be impeded by the thickness ofthe MRT film 120. Accordingly, optional third curing apparatus 312 may be positioned above fourth gap 332 and/or over fourth support roller 306. Third curing apparatus 312 comprises third UV light source 346 arranged to direct a third UV light 348 onto MRT film 120 and the light absorbing material 334. For example, as MRT film 120 advances around application roller 302 (e.g., a bottom portion of application roller 302), MRT film 120 is guided through fourth gap 332 and over fourth support roller 306 as fourth support roller 306 rotates in a counterclockwise direction. In this configuration, recesses 246, now filled with at least partially cured light absorbing material 334 are facing outward, away from sixth circumferential surface 326 such that light absorbing material 334 can be directly impinged by third UV light 348, thereby providing the desired cure. A refractive index difference between the cured MRT film 120 (e.g., MRT base layer 124) and the cured light absorbing material can be in a range from 0 to about 0.08, for example in a range from 0 to about 0.06, such as in a range from about 0 to about 0.05, in a range from about 0 to 0.04, or in a range from about 0 to about 0.03. For example, the refractive index of the cured light absorbing material may be in a range from about 1.45 to about 1.51. The resultant ambient contrast filter 106 may then be used in the manufacture of ambient contrast enhanced electroluminescent displays as disclosed herein.

[0115] While not shown, an additional second application roller and fifth support roller, as well as a third dispensing nozzle may be positioned downstream of fourth support roller 306 and a fourth curing apparatus, wherein the additional rollers, dispensing apparatus, and curing apparatus can be used to deposit a light absorbing layer 150 to the ACE layer 114. An AR layer 116 may be similarly added. However, light absorbing layer 150 may be applied simultaneously with recesses 246 using third support roller 304 and application roller 302 by adjusting the distance 322 between fourth circumferential surface 314 and fifth circumferential surface 318.

[0116] The apparatus described above in respect of FIGS . 30-31 provides a process in which the formation of the MRT film 120 with recesses and subsequent filling of the MRT film recesses with light absorbing material are conducted as separate, discrete processes. However, these processes need not be performed separately. That is, as described above, the MRT film 120 can be stored prior to being filled with light absorbing material. However, the steps described in respect of FIGS. 30-31 may be performed sequentially and continuously, one after the other, in an inline process. [0117] Accordingly, FIG. 32 depicts an inline process for forming an ACE layer 114. For purposes of description and not limitation, the process apparatus of FIG. 32 is arranged from right to left.

[0118] In accordance with FIG. 33, an apparatus 400 configured for inline manufacture of an ambient contrast filter 106 is shown. Apparatus 400 comprises a first support roller 402, a first dispensing nozzle 404, a first curing device 406, a first patterning roller 408, a second support roller 410, an application roller 412, a second dispensing nozzle 414, a second curing device 416, and a third support roller 418. Apparatus 400 may further include a third dispensing nozzle 420, a second patterning roller 422, a third curing device 424, and a fourth support roller 426.

[0119] As shown in FIG. 31, first patterning roller 408 is an elongate roller comprising a plurality of protrusions 430 (e.g., teeth) disposed about a first circumferential surface 432 of first patterning roller 408 and extending along a length of the first patterning roller. The plurality of protrusions 430 may be periodically spaced between adjacent protrusions or between groups of protrusions. For example, similar to patterning roller 204, each protrusion 430 of first patterning roller 408 can be spaced from an adjacent protrusion an equal distance such that the angular distance between each protrusion is equally divided. However, protrusions 430 may be differently spaced such that the angular distance between one pair of adjacent protrusions is different than the angular distance between another pair of adjacent protrusions. Protrusions 430 may be arranged in any predetermined pattern including any predetermined angular or circumferential distance between protrusions as desired.

[0120] First patterning roller 408 is rotatable about first axis of rotation 434. In various embodiments, protrusions 430 can extend along a length of first patterning roller 408 parallel with each other. For example, each protrusion 430 can be an elongate structure extending outward, away from first circumferential surface 432 a predetermined height Hl. Protrusions 430 may extend parallel with first axis of rotation 434. Alternatively, protrusions 430 may be arranged helically on first circumferential surface 432. Protrusions 430 may be arranged as necessary to obtain a distance between adjacent wedge-shaped features produced by the process in a range from about 40 pm to about 500 pm, for example from about 50 pm to about 200 pm, such as in a range from about 60 pm to about 150 pm, from about 60 pm to about 100 pm, or in a range from about 60 pm to about 90 pm, including all ranges and subranges therebetween. The height of protrusions 430 relative to first circumferential surface 432 along a line normal to first circumferential surface 432 may vary. For example, some protrusions may have a height H2 different than Hl, for example less than Hl .

[0121] First support roller 402 is an elongate roller comprising a second circumferential surface 436 and is rotatable about second axis of rotation 438. Second circumferential surface 436 can be a smooth surface. Second axis of rotation 438 may extend parallel with first axis of rotation 434. Second circumferential surface 436 may be spaced from first circumferential surface 432 by a first predetermined distance 440. That is, first circumferential surface 432 is separated from second circumferential surface 436 by a first gap 442. First predetermined distance 440 may be equal to or greater than a maximum height of protrusions 430.

[0122] Second support roller 410 is an elongate roller comprising a third circumferential surface 444 and is rotatable about third axis of rotation 446. Third circumferential surface 444 can be a smooth surface. In embodiments, third axis of rotation 446 may extend parallel with first axis of rotation 434. Third circumferential surface 444 can be spaced from first circumferential surface 432 by a second predetermined distance 448. That is, first circumferential surface 432 is separated from third circumferential surface 444 by a second gap 450. Second predetermined distance 448 may be equal to or greater than a maximum height of protrusions 430. First axis of rotation 434, second axis of rotation 438, and third axis of rotation 446 may be coplanar.

[0123] First dispensing nozzle 404 is configured to direct matrix material 452 into first gap 442 between first patterning roller 408 and first support roller 402. For example, dispensing nozzle 404 may be in fluid communication with a source of matrix material 452 in liquid form and positioned above first gap 442. Matrix material 452 can be pumped to first dispensing nozzle 404.

[0124] As depicted in FIG. 33, as support layer 125 is fed into first gap 442, matrix material 452 is also dispensed into first gap 442 in liquid form by first dispensing nozzle 404 from above first gap 442, wherein the matrix material 452 is captured in first gap 442 between first patterning roller 408 and first support roller 402, and more specifically, between support layer 125 and first patterning roller 408. Protrusions 430 displace matrix material 452 in first gap 442 as first patterning roller 408 and first support roller 402 rotate. For example, as depicted in FIG. 33, the process runs from right to left, wherein first patterning roller 408 rotates in a clockwise direction and first support roller 402 rotates in a counterclockwise direction. As matrix material 452 leaves first gap 442, matrix material 452 is cured by first curing device 406 positioned below first gap 442 and/or first patterning roller 408 and becomes MRT base layer 124 bonded to support layer 125 to form MRT film 120. Matrix material 452 may be an ultraviolet (UV) light-curable polymer material. Accordingly, first curing device 406 may comprise a UV lighting device 454 arranged to emit a first UV light 456 upward into first gap 442 and/or toward support layer 125 beneath first patterning roller 408, thereby curing the matrix material 452 into MRT film 120 comprising MRTbase layer 124 comprising a plurality of recesses 460 that mimic protrusions 430 and support layer 125. Recesses 460 are the negative of protrusions 430.

[0125] As further illustrated in FIG. 32, as first patterning roller 408 rotates in the clockwise direction, MRT film 120 travels under first patterning roller 408, with protrusions 430 engaged in recesses 460. MRT film 120 is then guided into second gap 450 and wraps over second support roller 410 such that recesses 460 face outward, away from third circumferential surface 444.

[0126] Third circumferential surface 444 of second support roller 410 is separated from fourth circumferential surface 462 of application roller 412 by a predetermined distance 464. That is, third circumferential surface 444 of second support roller 410 is separated from fourth circumferential surface 462 of application roller 412 by a third gap 466. MRT film 120 travels over third circumferential surface 444 of second support roller 410 and is directed into third gap 466. MRT film 120 advances over second support roller 410 with recesses 460 facing outward, away from third circumferential surface 444. As MRT film 120 enters third gap 466 between application roller 412 and second support roller 410, recesses 460 are facing fourth circumferential surface 462 of application roller 412. Light absorbing material 468 is dispensed in liquid form by second dispensing nozzle 414 into third gap 466 and forced into recesses 460 by application roller 412. Predetermined distance 464 may be adjusted such that, in addition to filling recesses 460 with light absorbing material 468, the light absorbing material may form a continuous layer over MRT film 120. As MRT film 120 exits third gap 466, light absorbing material 468 (including a light absorbing layer 150 if applied) is cured by second curing apparatus 416 to form wedge-shaped features 118 (and/or wedge-shaped features 160 and/or light absorbing layer 150). For example, light absorbing material 468 may be an ultraviolet (UV) light-curable polymer material. Accordingly, second curing apparatus 416 may comprise a UV light emitting device 470 arranged to direct a second UV light 472 into third gap 466, wherein light absorbing material 468 is at least partially cured by second curing apparatus 416 to form wedge-shaped features 118 and optionally light absorbing layer 150, e g , ACE layer 114. Application roller 412 is configured to rotate about fourth axis of rotation 472, and as application roller 412 rotates, ACE layer 114 is guided around at least a portion of application roller 412 (e.g., beneath the application roller) and into contact with fifth circumferential surface 480 of third support roller 418.

[0127] Third support roller 418 is rotatable about fifth axis of rotation 478. Fifth circumferential surface 480 may be a smooth surface. Fifth axis of rotation 478 may be parallel with first axis of rotation 434. As shown in FIG. 32, ACE layer 114 rides over third support roller 418 and may be collected from third support roller 418. For example, in some embodiments, ACE layer 114 including the at least partially cured light absorbing material may be directed to downstream equipment (not shown) configured to process (e.g., roll) ACE layer 114 for later use. Elowever, additional layers may be added to ACE layer 114. For example, apparatus 400 may further include second patterning roller 422 rotatable about a sixth circumferential surface 482 rotatable about a sixth axis of rotation 484. Sixth circumferential surface 482 may be spaced from fifth circumferential surface 480 by a third predetermined distance 486. That is, sixth circumferential surface 482 is separated from fifth circumferential surface 480 by a fourth gap 488. As ACE layer 114 leaves fifth circumferential surface 480 of third support roller 418, ACE layer 114 is directed into fourth gap 488. Third dispensing nozzle 420 can be arranged to direct a flow of polymer resin 490 into fourth gap 488 between second patterning roller 422 and ACE layer 114. Polymer resin 490 may comprise, for example, functional acrylates such as 1,6 hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA) or functional methacrylates like trimethylolpropane trimethacrylate (TMPTMA), or any combination thereof. In some instances, the Sixth circumferential surface 482 is a textured surface, for example a roughened surface, having a predetermined roughness. Referring to FIG. 32, ACE layer 114 is oriented such that polymer resin 490 comes into contact with wedge-shaped features 118 (and/or wedge- shaped features 160) or light absorbing layer 150 if applied, thereby forming AR layer 116. Because polymer resin 490 is contacted by sixth circumferential surface 482, the texture present on sixth circumferential surface 482 is impressed on the outward facing surface of the polymer resin. Third curing apparatus 424 is positioned below fourth gap 488 and/or second patterning roller 422 and comprises a UV lighting device 494 configured to direct a third UV light 496 through ACE layer 114 to at least partially cure polymer resin 490 and forming ambient contrast filter 106. In some instances, AR layer 116 can be an inorganic layer, for example SiCh. AR layer 490 shouldhave a transparency of at least 90% at the applied thickness. [0128] It should be apparent from the present disclosure that the various rollers of apparatus 400 can be interchanged such that different layers of ambient contrast filter 106 can be arranged differently compared to the arrangement provided by the embodiment of FIG. 33. In other words, the various paterning rollers, dispensing nozzles, and curing apparatus can be arranged as appropriate to produce ambient contrast filters with various number and orders of layers.

[0129] Non-limiting examples of display devices having an ambient contrast filter 106 with various arrangements of layers can be seen in FIG. 33-36. FIG. 33 depicts an exemplary display device 100 comprising a backplane substrate 102 including a plurality of electroluminescent elements 104 disposed thereon, display device 100 including an ambient contrast filter 106 disposed overtop the backplane substrate 102. Ambient contrast filter 106 comprises, from botom to top, an ACE layer 114 including a support layer 125 and an MRT base layer 124, MTR base layer 124 comprising a plurality of wedge-shaped features 118 disposed therein. A light absorbing layer 150 is disposed overtop the MRT base layer 124. Ambient contrast filter 106 may be atached to backplane substrate 102 by an adhesive layer 122. In the embodiment of FIG. 33, the ambient contrast filter 106 does not include a glass substrate layer (e.g., glass substrate layer 112), and the ambient contrast filter is attached directly to the backplane substrate 102 and/or the electroluminescent elements 104. That is, the display device of FIG. 33 does not include a glass cover plate over the backplane and electroluminescent elements.

[0130] FIG. 34 depicts another exemplary display device 100 comprising a backplane substrate 102 including a plurality of electroluminescent elements 104 disposed thereon, display device 100 including an ambient contrast filter 106 disposed overtop the backplane substrate 102. The ambient contrast filter 106 of FIG. 35 is similar to the ambient contrast filter 106 of FIG. 34, except that the ambient contrast filter of FIG. 34 further comprises an antireflection layer overtop the light absorbing layer 150. The ambient contrast filter 106 of FIG. 34 may be atached to backplane substrate 102 by an adhesive layer 122. Similar to the display device of FIG. 33, the ambient contrast filter 106 of FIG. 34 does not include a glass substrate layer, and the ambient contrast filter is attached directly to the backplane substrate 102 and/or the electroluminescent elements 104. That is, the display device of FIG. 35 does not include a glass cover plate over the backplane and electroluminescent elements.

[0131] FIG. 35 depicts still another exemplary display device 100 comprising a backplane substrate 102 including a plurality of electroluminescent elements 104 disposed thereon, display device 100 including an ambient contrast filter 106 disposed overtop the backplane substrate 102. The ambient contrast filter 106 of FIG. 35, from bottom to top, comprises a light absorbing layer 150, an MRT base layer comprising a plurality of wedge-shaped features 118 disposed therein, and a support layer 125 disposed overtop the MRT base layer. The ambient contrast filter 106 of FIG. 35 may be atached to backplane substrate 102 by an adhesive layer 122. Similar to the display devices of FIG. 33 and 34, the ambient contrast fdter 106 of FIG. 35 does not include a glass substrate layer, and the ambient contrast fdter is attached directly to the backplane substrate 102 and/or the electroluminescent elements 104. That is, the display device of FIG. 35 does not include a glass cover plate over the backplane and electroluminescent elements.

[0132] FIG. 36 depicts yet another exemplary display device 100 comprising a backplane substrate 102 including a plurality of electroluminescent elements 104 disposed thereon, display device 100 including an ambient contrast fdter 106 disposed overtop the backplane substrate 102. The ambient contrast fdter 106 of FIG. 36, from bottom to top, comprises an AR layer 116, a support layer 125, an MRT base layer comprising a plurality of wedge-shaped features 118 disposed therein, a light absorbing layer 150, and a second AR layer 116 disposed overtop the light absorbing layer, and a support layer 125 disposed overtop the MRT base layer. The ambient contrast fdter 106 of FIG. 36 may be attached to backplane substrate 102 by an adhesive layer 122. Similar to the display devices of FIG. 33-35, the ambient contrast fdter 106 of FIG. 36 does not include a glass substrate layer, and the ambient contrast fdter is attached directly to the backplane substrate 102 and/or the electroluminescent elements 104. That is, the display device of FIG. 36 does not include a glass cover plate over the backplane and electroluminescent elements.

[0133] FIG. 37 is a plot showing several optical characteristics of the structures shown in FIGS. 33-36. Transmission (T) was measured by spectrometer and ACR (Ambient Contrast Ratio) was measured based on IEC 62341-6-2 using a plasma display panel. T and ACR can be adjusted by changing structure and material selection. The data show that an AR layer overtop the wedge-shaped features showed little increase of transmission, with similar ACR, when compared with the No AR case. On the other hand, an AR layer disposed on the support layer side showed an optical transmission of 43.6%, similar to the No-AR case. However, ACR increased to 140. It is believed the reason the percent transmission remained the same as the No-AR case, or even lower, is that transmission was decreased by reversing the orientation of the wedge-shaped feature pattern wherein the bottom side light inlet is decreased by the reversal. The double-sided AR structure showed the highest transmission of the four cases, with a similar level of ACR as the first and second cases.

[0134] It will be apparent to those skilled in the art that various modifications and variations can be made to embodiments of the present disclosure without departing from the spirit and scope of the disclosure . Thus, it is intended that the present disclosure cover such modifications and variations provided they come within the scope of the appended claims and their equivalents.

Claims

CLAIMS What is claimed is:

1. An optical display device, comprising: a backplane substrate comprising a plurality of electroluminescent elements deposited in parallel rows thereon, each row of electroluminescent elements comprising an alignment axis; an ambient contrast filter positioned over the backplane substrate, the ambient contrast filter comprising a polymer support layer and a micro-replicated thin film base layer disposed on the polymer support layer, the micro-replicated thin film base layer comprising a plurality of light absorbing wedge-shaped features arranged in parallel rows, each light absorbing wedge-shaped feature comprising a longitudinal axis; and wherein the ambient contrast filter does not include a glass layer.

2. The optical display device of claim 1, wherein the ambient contrast filter further comprises a light absorbing layer disposed on the micro-replicated thin film base layer.

3. The optical display device of claim 2, wherein a thickness of the light absorbing layer is in a range from about 10 nm to about 1 pm.

4. The optical display device of claim 1, wherein a height Hl of the plurality of wedge-shaped features is in a range from about 10 pm to about 100 pm.

5. The optical display device of claim 4, wherein Hl is in a range from about 10 pm to about 40 pm.

6. The optical display device of claim 5, wherein each wedge-shaped feature of the plurality of wedge-shaped features comprises a maximum cross-sectional width W1 in a range from about 5 pm to about 15 pm.

7. The optical display device of claim 6, wherein Hl/Wl is equal to or greater than about 2.

32

8. The optical display device of claim 7, wherein Hl/Wl is in a range from about 2 to about

6.

9. The optical display device of claim 1, wherein a pitch Pl of the plurality of wedge-shaped features is in a range from about 5 pm to about 40 pm

10. The optical display device of claim 1, wherein an angle between a base of each wedge- shaped feature of the plurality of wedge-shaped features and an adjacent side wall of each wedge-shaped feature is in a range from about 85 degrees to less than 90 degrees.

11. The optical display device of claim 1, wherein the ambient contrast filter comprises an anti-reflection layer.

12. The optical display device of claim 2, wherein the ambient contrast filter comprises an anti-reflection layer disposed on the light absorbing layer.

13. The optical display device of claim 1, wherein an index of refraction of the plurality of wedge-shaped features is nn and an index of refraction of the micro-replicated thin film base layer is nr, An = im-nr. and -0.3 < An < 0.

14. A method of forming an ambient contrast filter, comprising: rotating a first patterning roller in a first direction, the first patterning roller comprising a first circumferential surface comprising a plurality of protrusions extending therefrom; rotating a first support roller in a second direction opposite the first direction, the first support roller comprising a second circumferential surface spaced from the first circumferential surface by a first gap; rotating a second support roller in the second direction, the second support roller comprising a third circumferential surface, the third circumferential surface spaced from the first circumferential surface by a second gap, the first patterning roller positioned between the first support roller and the second support roller; directing a polymer support layer into the first gap; dispensing a polymer matrix material into the first gap between the support layer and the first circumferential surface of the first patterning roller, the first patterning roller forming a plurality of recesses in the polymer matrix material; and

33 irradiating the support layer and the polymer matrix material with a first UV light, the first UV light curing the polymer matrix material to form a micro-replicated thin film base layer bonded to the support layer, the micro-replicated thin film base layer and the support layer forming a micro-replicated thin film.

15. The method of claim 14, further comprising directing the micro-replicated thin film into a third gap between the third circumferential surface of the second support roller and a fourth circumferential surface of an application roller rotating in the first direction, dispensing a light absorbing material into the third gap between the micro-replicated thin film and the fourth circumferential surface of the application roller, the light absorbing material filling the recesses, and irradiating the light absorbing material with a second UV light to at least partially cure the light absorbing material and form a plurality of light absorbing wedge-shaped features in the micro-replicated thin film base layer, the support layer, the micro -replicated thin film base layer, and the plurality of light absorbing wedge-shaped features forming an ambient contrast enhancement layer.

16. The method of claim 15, further comprising directing the ambient contrast enhancement layer into a fourth gap between a fifth circumferential surface of a third support roller downstream of the application roller and a sixth circumferential surface of a second patterning roller, dispensing a second polymer material into the third gap between the ambient contrast enhancement layer and the fifth circumferential surface of the third support roller, and irradiating the second polymer material with a third UV light to at least partially cure the second polymer material, the cured second polymer material forming an IR layer bonded to the ambient contrast enhancement layer.

17. The method of claim 16, wherein the second patterning roller comprises a roughened circumferential surface.

18. The method of claim 14, wherein a viscosity of the polymer matrix material during the dispensing is in a range from about 50 mPa-s to about 1000 mPa-s.