CN116490988A

CN116490988A - Optical display device with enhanced environmental contrast and method of manufacturing the same

Info

Publication number: CN116490988A
Application number: CN202180079371.1A
Authority: CN
Inventors: 郑相澈; 金大渊; 李龟洙; 李庚珍; 申东根; 尹洪
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2020-11-06
Filing date: 2021-11-03
Publication date: 2023-07-25
Also published as: TW202226585A; JP2023548602A; WO2022098683A1

Abstract

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

Description

Optical display device with enhanced environmental contrast and method of manufacturing the same

Cross Reference to Related Applications

The present application claims priority from korean patent application No. 10-2020-0147757 filed on 11/6/2020, 35u.s.c. ≡119, the content of which is the basis of the present application and incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to optical display devices, and more particularly to optical display devices including an ambient contrast enhancement layer configured to improve display image contrast in the presence of ambient light.

Background

Ambient light is a problem for self-emissive electroluminescent displays such as Organic Light Emitting Diode (OLED) and micro light emitting diode (micro LED) displays. A display panel with a surface comprising metal electrodes and/or other reflective materials may reflect light from solar radiation or room illumination. For example, an OLED panel may have a surface reflectivity of approximately 80%, mainly due to metal electrodes. Circular polarizers are often used as optically functional films to reduce ambient light reflection and avoid display contrast ratio loss. However, such a polarizing film absorbs up to 50% of incident light, and thus may reduce display brightness.

Disclosure of Invention

An optical display device including an environmental contrast enhancement layer adjacent a backplane substrate is described herein. The backplane substrate may include a plurality of electroluminescent elements deposited thereon. The environmental contrast enhancement layer may include a plurality of light absorbing wedge-shaped features arranged in a row.

Accordingly, an optical display device is disclosed that includes a backplane substrate including a plurality of electroluminescent elements deposited thereon in parallel rows, each row of electroluminescent elements including an alignment axis. The display device further includes an environmental contrast filter disposed over the backplane substrate, the environmental contrast filter including a polymeric support layer and a microreplicated film base layer disposed on the polymeric support layer, the microreplicated film base layer including a plurality of light absorbing wedge features arranged in parallel rows, each light absorbing wedge feature including a longitudinal axis. Furthermore, the environmental contrast filter does not include a glass substrate layer.

The environmental contrast filter may further include a light absorbing layer disposed on the microreplicated film base layer. The thickness of the light absorbing layer may be about 10 nanometers (nm) to about 1 micrometer (μm).

The height H1 of the plurality of wedge-shaped features may be about 10 μm to about 100 μm, for example about 10 μm to about 40 μm.

Each wedge-shaped feature of the plurality of wedge-shaped features may include a first maximum cross-sectional width W1 of about 5 μm to about 15 μm.

The H1/W1 ratio may be equal to or greater than about 2, such as about 2 to about 6.

The pitch P1 of the plurality of wedge-shaped features may be about 5 μm to about 40 μm.

The angle between each wedge feature base of the plurality of wedge features and the respective wedge feature adjacent sidewall may be about 85 degrees to less than 90 degrees.

The environmental contrast filter may include an anti-reflective layer. For example, an anti-reflection layer may be disposed on the light absorbing layer.

The plurality of wedge-shaped features have a refractive index n _B A refractive index of the base layer of the micro-replicated film is n _F ，Δn＝n _B －n _F And-0.3<Δn<0。

Also described is a method of forming an environmental contrast filter, the method comprising rotating a first patterned roll in a first direction, the first patterned roll comprising a first circumferential surface comprising a plurality of protrusions extending therefrom. The method may further include rotating the first support roller in a second direction opposite the first direction, the first support roller including a second circumferential surface separated from the first circumferential surface by a first gap. The method may include rotating a second support roller in a second direction, the second support roller including a third circumferential surface separated from the first circumferential surface by a second gap, the first patterned roller positioned between the first support roller and the second support roller. The method includes directing a polymeric support layer into a first gap, dispensing a polymeric matrix material into the first gap between the support layer and a first circumferential surface of a first patterned roll, the first patterned roll forming a plurality of recesses in the polymeric matrix material, and irradiating the support layer and the polymeric matrix material with a first UV (ultraviolet) light that cures the polymeric matrix material to form a microreplicated film substrate layer engaging the support layer, the microreplicated film substrate layer and the support layer forming a microreplicated film.

The method may further include directing the microreplicated film into a third gap between a third circumferential surface of the second backup roll and a fourth circumferential surface of the applicator roll that rotates in the first direction; dispensing a light absorbing material into a third gap between the microreplicated film and a fourth circumferential surface of the applicator roll, the light absorbing material filling the recess; 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 features in the microreplicated film substrate layer. The support layer, the microreplicated film base layer, and the plurality of light absorbing wedge features form an environmental contrast enhancement layer.

The method may still further include directing the environmental 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 the second patterned roller, dispensing a second polymeric material into the third gap between the environmental contrast enhancement layer and the fifth circumferential surface of the third support roller, and irradiating the second polymeric material with third UV light to at least partially cure the second polymeric material, the cured second polymeric material forming an IR layer that engages the environmental contrast enhancement layer.

The second patterned roll may include a roughened circumferential surface.

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

The foregoing general description and the following detailed description are intended to provide an overview or framework to understanding the nature and character of the embodiments described herein. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings depict various embodiments of the present disclosure and are used in conjunction with the description to explain the principles and operation of the embodiments.

Drawings

FIG. 1 is a schematic diagram of an electroluminescent display employing a circular polarizer;

FIG. 2 is a schematic diagram of an electroluminescent display according to embodiments described herein;

FIG. 3 is a top view of an exemplary pixel and shows the angled wedge feature positioned atop an electroluminescent element;

FIG. 4A is a partial cross-sectional side view of the electroluminescent display of FIG. 2 and showing elements of a contrast enhancement layer;

FIG. 4B is a close-up cross-sectional view (not filled for clarity) of the wedge-shaped feature shown in FIG. 5A;

FIG. 5 is a graph showing the transmittance of a modeled cover plate as a function of feature width W1;

FIG. 6 is a graph showing the transmittance as a function of LED emission angle for different wedge feature heights H1;

FIG. 7 is a graph showing reflectance versus angle of incidence for different wedge feature heights H1;

FIG. 8 is a schematic diagram illustrating the intersection of electroluminescent element emitted light with wedge-shaped features according to embodiments described herein;

FIG. 9 is a partial close-up view of FIG. 8;

FIG. 10 is a graph of modeled and dimensionless light intensity for several Δn values as a function of viewing angle (θ _V ) The change map is compared with Lambertian distribution;

FIG. 11 is a graph showing modeled transmittance between a cover plate including wedge features (WSF) 118 and a display device including a Circular Polarizer (CP);

FIG. 12 is a graph showing modeled reflectivity between a cover plate including wedge features (WSFs) 118 and a display device including a Circular Polarizer (CP);

FIG. 13 is a cross-sectional view of an environmental contrast filter including a selective light absorbing layer disposed on the MRT base layer, for example, between the MRT base layer and the substrate layer 112;

FIG. 14 is a graph of the natural logarithm (ln) of the modeled transmittance of the light absorbing layer as a function of thickness (in microns) at a wavelength of 550 nm;

FIG. 15 is a graph of absorbance of a light absorbing layer at a wavelength of 550nm as a function of thickness (in microns);

Fig. 16 shows the theoretical prediction of the light transmittance (or light absorptivity) of the thin absorbing layer 150 for layer thickness d (0.1 μm to 10 μm) and its extinction coefficient k as a function of transmittance T;

FIG. 17 is a graph of transmittance versus pitch P1 for different k values and wedge feature heights H1 μm;

FIG. 18 is a graph of modeled reflectance versus pitch for different k values and wedge feature heights H1 50 μm;

FIG. 19 is a graph of modeled reflectance versus pitch for different k values and wedge feature heights H1 μm;

FIG. 20 shows modeled dimensionless intensity as a function of electroluminescent element emission angle with and without an absorber layer for a wedge feature height H1 50 μm;

FIG. 21 shows modeled dimensionless intensity as a function of electroluminescent element emission angle with and without an absorber layer for a wedge feature height H1 μm;

FIG. 22 is a graph showing modeled ambient contrast ratio versus total reflection for an ambient contrast filter;

FIG. 23 is a partial cross-sectional view of an environmental contrast filter including a substrate layer and an ACE layer including a plurality of wedge-shaped features of different heights buried therein;

FIG. 24 is a graph showing modeled transmittance versus pitch for an environmental contrast filter including two wedge-shaped features of different heights;

FIG. 25 is a graph showing modeled reflectivity versus pitch for an environmental contrast filter including two wedge-shaped features of different heights;

FIG. 26 is a graph showing modeled transmittance data versus second height for a display device having two pluralities of wedge-shaped features of different heights;

FIG. 27 is a graph showing modeled reflectance data versus second height for a display device having two pluralities of wedge-shaped features of different heights;

FIG. 28 is a modeled angular emission profile of light emitted by electroluminescent elements of a display having a single (first) plurality of wedge-shaped features and a display having two (first and second) pluralities of wedge-shaped features;

FIG. 29 is a cross-sectional view of another electroluminescent display device according to the present disclosure, including a back plate substrate including a plurality of electroluminescent elements deposited thereon and an environmental contrast filter disposed over the back plate substrate, the environmental contrast filter lacking a glass substrate layer;

FIG. 30 is a side view of a first step processing apparatus configured to manufacture an MRT film comprising an MRT substrate layer and a support layer;

FIG. 31 is a side view of a second step processing apparatus for fabricating an environmental contrast filter using the MRT film fabricated by the apparatus of FIG. 30;

FIG. 32 is a side view of another processing apparatus for manufacturing an environmental contrast filter in a continuous in-line process;

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

FIG. 34 is a cross-sectional side view of another exemplary display device according to an embodiment of the present disclosure;

FIG. 35 is a cross-sectional side view of yet another exemplary display device according to an embodiment of the present disclosure;

FIG. 36 is a cross-sectional side view of yet another exemplary display device according to an embodiment of the present disclosure; and

fig. 37 is a graph showing measured light transmittance versus ambient contrast ratio of the ambient contrast filter on the apparatus shown in fig. 33 to 36.

Detailed Description

Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

The term "about" as used herein means that the amounts, dimensions, formulations, parameters, and other quantities and characteristics are not and not necessarily exact, but may be approximated and/or otherwise reflecting tolerances, conversion factors, rounding off, measurement error and the like and other factors known to those of skill in the art to be desirably greater or lesser

Ranges may be expressed herein as from "about" a particular value, and/or to "about" another particular value. In this regard, another embodiment includes from the particular value to the other particular value. Likewise, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value may constitute 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.

Directional terms used herein (e.g., up, down, right, left, front, back, top, bottom) are used with reference only to the drawings and are not intended to obscure the orientation of the bits.

Unless explicitly stated otherwise, any method mentioned herein is not intended to be construed as requiring any particular order of method steps or any equipment, particular orientation. Accordingly, no attempt is made to infer any order or orientation of elements when method claims do not actually recite an order or orientation of the steps, or any apparatus claim does not actually recite an order or orientation of the elements, or the appended claims or embodiments do not specifically point out that the steps are limited to a specific order or orientation of the elements. This applies to any possible non-explicit interpretation basis, including: step arrangement, operational flow, component order, or component orientation related logic matters; obvious meaning derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.

As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, unless the context clearly indicates otherwise, reference to "a" or "an" component includes aspects having two or more such components.

As used herein, "exemplary," "example," or various word forms are meant to be taken as examples, instances, or illustrations. Any aspect or design described herein as "exemplary" or "example" is not necessarily to be construed as preferred or advantageous over other aspects or designs. In addition, the examples are provided for illustration and understanding purposes only and are not intended to limit or restrict the objects or relevant portions of the present disclosure in any way. It should be appreciated that various additional or alternative examples of the different scope may be presented, but for simplicity, the description has been omitted.

The terms "comprising," "including," and variations thereof as used herein, are to be construed as synonymous, open-ended terms unless otherwise indicated. The list of enumerated elements following the rolling phrase "comprising" or "includes" is not a unique list, and therefore, other elements may exist in addition to the list of specifically enumerated elements.

The terms "substantially", "essentially" and variations thereof as used herein are intended to mean that the feature is equal to or nearly equal to a certain value or description. For example, a "substantially planar" surface is intended to refer to a planar or nearly planar surface. Furthermore, "substantially" is intended to mean that the two values are equal or nearly equal. In some embodiments, "substantially" may mean that the values are not more than about 10% different from each other, such as not more than about 5% different from each other or not more than about 2% different from each other.

As used herein, a "circumferential surface of a roll" is an outer surface of the roll that extends around the circumference of the roll.

Electroluminescent displays may suffer from surface reflection resulting in a reduced environmental contrast. For example, FIG. 1 shows a partial cross-sectional image of a micro LED display 10, the display 10 including a back-plate substrate 12, the back-plate substrate 12 including a plurality of electroluminescent elements 14 (e.g., LEDs) deposited thereon. The electroluminescent display 10 further comprises a cover plate 18. The cover plate 18 may include a phase retardation layer 20 and a linear polarization layer 22, which together form a circular polarizer 24. As shown in fig. 1, ambient light 26 enters the display via the cover plate 1810 at a normal to the first surface 28 at an incident angle θ _inc Incident from the first surface 28 of the back-plate substrate 12 and then at a reflection angle θ _ref Reflected from the back-plate substrate 12, as represented by ray 30. The plurality of electroluminescent elements 14 also generate and emit light, represented by light rays 32. The emitted light 32 may penetrate the cover plate 18 as an image in the direction of an outside observer 34. The reflected ambient light 30 competes with the emitted light 32 such that the contrast of the displayed image is reduced when viewed by a viewer 34. As such, the display 10 or some portion appears to be whitened to the viewer.

To avoid environmental contrast degradation, contrast enhancement layers are provided for electroluminescent display applications, including Light Emitting Diode (LED) displays, organic Light Emitting Diode (OLED) displays, or quantum dot displays, but are particularly beneficial for micro LED displays. The contrast enhancement layer may include a microreplicated contrast enhancement film configured to inhibit the reflection of ambient light competing with the light emitted by the electroluminescent element. Electroluminescent displays may have pixel dimensions on the order of tens to hundreds of microns. For example, an electroluminescent display may include red (R), green (G), and blue (B) LEDs, each set of red, green, and blue LEDs forming a pixel. The size of the micro-LEDs (e.g., along the dimension of the LED side) may be about 10 μm to about 1000 μm. For example, the LED chip may be sized to have an area of about 10 μm ² To about 1000 μm ² . In this embodiment, the light emitting area size of each LED chip may be less than about 20% of the pixel area.

The contrast enhancement layer may include elements for reducing or eliminating reflection of ambient light from the pixel or pixel component. As described herein, the elements may include a plurality of light absorbing wedge-shaped features, such as trapezoid features, arranged in rows. The wedge-shaped features may be numerically evaluated and optimized to reduce or eliminate ambient light reflected by the pixel electroluminescent elements (e.g., individual LEDs).

Fig. 2 is a cross-sectional view of an exemplary electroluminescent display device 100 according to the present disclosure, including a backplane substrate 102 including a plurality of electroluminescent elements 104 deposited thereon and an environmental contrast filter 106. The electroluminescent elements 104 may comprise individual pixel elements of an image pixel and, thus, may be configured to display different colors, such as red (R), green (G), and blue (B). The environmental contrast filter 106 may be separated from the backplate substrate 102 by an air gap 110. The air gap 110 may be about 50 μm to about 5 millimeters (mm), such as about 100 μm to about 5mm, such as about 200 μm to about 4mm, about 300 μm to about 3mm, or about 1mm to about 3mm, including all ranges and subranges therebetween.

The environmental contrast filter 106 may include a substrate layer 112, an environmental contrast enhancement (ACE) layer 114, and a selective anti-reflection (AR) layer 116. The substrate layer 112 may comprise a glass material, such as a silicate glass material, such as an aluminosilicate glass material, although the substrate layer 112 may comprise a polymer material. The AR layer 116 may be joined to the substrate layer 112 by an adhesive layer 122 (e.g., pressure sensitive adhesive).

ACE layer 114 includes a first plurality of light absorbing features, such as wedge-shaped features 118, disposed in a microreplicated film (MRT film 120). The MRT film 120 in turn includes an MRT base layer 124 disposed on a support layer 125. The support layer 125 may include a polymeric material, such as polyethylene terephthalate (PET). Wedge-shaped features 118 are separated by light transmissive regions 126 within the MRT substrate layer 124.

The first plurality of light absorbing wedge-shaped features 118 may comprise any suitable material capable of absorbing or blocking at least a portion of the visible spectrum of light. For example, the light absorbing feature may include a black colorant, such as black particles, such as carbon black. The carbon black may include a particle size equal to or less than about 500nm, such as from about 10nm to about 500nm, from about 10nm to about 400nm, from about 10nm to about 300nm, or from about 10nm to about 200nm, including all ranges and subranges therebetween. However, the light absorbing material may include colorants having other colors such as white, red, green, or yellow. The light absorbing material (e.g., carbon black, pigment or dye, or a combination thereof) may be dispersed in a suitable matrix material, such as a polymer resin.

Fig. 3 is a partial top view (e.g., a single pixel) of the electroluminescent display from the viewer side of the display and shows a first plurality of elongated wedge-shaped features 118 arranged in parallel rows, each wedge-shaped feature of the first plurality including a longitudinal axis 136. As shown, the wedge-shaped features 118 are elongated structures located between the electroluminescent element and the viewer. As also shown, the first plurality of wedge-shaped features 118 may not be aligned with the alignment axis 138 of the electroluminescent element 104, but may be at an angle σ with respect to the alignment axis 138 and the electroluminescent element. The angle σ may be in a range of about 0 degrees to about 10 degrees, such as greater than 0 degrees to about 10 degrees.

The design conditions of ACE layer 114 may be confirmed by parametric studies of the structural changes and refractive index of the wedge features. For example, in some embodiments, the maximum width W1 measured by the individual wedge-shaped features of the first plurality of wedge-shaped features in the wedge-shaped feature substrate 140 may be less than half (L (pixel)/2) of the display pixel length L (pixel) for a transmittance T greater than 50%. Transmittance is the ratio of the transmitted light power through a given geometry to the incident light power in the normal direction. For example, the maximum width W1 of the wedge-shaped feature 118 may be about 10 μm to about 100 μm. For some specific backplane substrate designs (e.g., LED chip size: 38×54 μm ² L (pixel) =432 μm, D (chip-to-chip) =100 μm), W1 may be about 5 μm to about 25 μm, e.g., about 5 μm to about 20 μm, e.g., about 5 μm to about 15 μm. L (pixels) may be about 10 μm to about 1000 μm.

Fig. 4A and 4B illustrate a portion of the environmental contrast filter 106 and show the dimensional parameters of the wedge feature 118. Each of the first plurality of wedge-shaped features 118 may include a maximum width W1 measured at the feature base 140 (see fig. 4B, which is not filled for clarity), a height H1 of the wedge-shaped feature base 140 to the opposite end 142 measured, a pitch P1 of the center-to-center spacing of the wedge-shaped features 118 immediately adjacent the wedge-shaped features 118 measured, and a wedge angle β between the base 140 of the wedge-shaped features 118 and the wedge-shaped feature adjacent side 144 measured.

In some embodiments, the wedge angle β may be about 70 degrees to less than 90 degrees, such as about 75 degrees to less than 90 degrees, such as about 80 degrees to less than 90 degrees or about 85 degrees to less than 90 degrees. As such, the maximum width W1 of the substrate 140 is greater than the narrower width of the opposite end 142. In other words, the wedge-shaped feature may comprise a trapezoidal cross-sectional shape, wherein the opposite ends 142 protrude from the substrate 140 toward the plurality of electroluminescent elements 104. This arrangement may improve ambient light reduction while providing a larger viewing angle for the electroluminescent display. Viewing angle is the angle at which the luminance of an electroluminescent display is half of the luminance measured by a viewer along the normal of the electroluminescent display (e.g., the normal of the cover plate).

Fig. 5 is a graph showing modeled ambient contrast filter transmittance as a function of feature width W1. The data shows that as the wedge feature width W1 decreases, the transmittance increases.

Fig. 6 and 7 show the transmittance and reflectance of different wedge feature heights H1 as a function of LED emission angle (fig. 6) and incident angle (fig. 7), respectively. The data shown in fig. 6 shows that as the wedge feature height H1 decreases, the transmittance desirably increases. Conversely, the data shown in FIG. 7 shows that as the wedge feature height H1 decreases, the reflectivity desirably increases. As the emission angle of the electroluminescent element increases, the transmittance decreases. As the angle of incidence of ambient light increases, the reflectivity decreases until the angle of incidence reaches about 60 °, a divergence occurs between a large height (greater than about 50 μm) and a small height (less than about 50 μm, e.g., 20 μm). For heights H1 of 20 μm and 10 μm and incident angles greater than about 60 °, the reflectivity increases but decreases at heights of about 50 μm to about 150 μm. The wedge feature height requires a trade-off between transmittance and reflectance to find the optimal height H1 for a particular display device configuration.

The height H1 may be about 10 μm to about 100 μm, such as about 10 μm to about 80 μm, about 10 μm to about 60 μm, such as about 10 μm to about 40 μm. The height to width aspect ratio H1/W1 of the wedge-shaped features 118 may be equal to or greater than about 2, such as equal to or greater than about 3. For example, the aspect ratio H1/W1 may be about 2 to about 6 or about 3 to about 5, or less than about 5 or less than about 4.

The pitch P1 of the wedge-shaped features 118 may be about 5 μm to about 500 μm, such as about 5 μm to about 200 μm, for example about 5 μm to about 100 μm, about 5 μm to about 60 μm, or about 5 μm to about 40 μm, including all ranges and subranges therebetween.

Furthermore, each wedge-shaped feature 118 may include a refractive index n _B The MRT substrate layer 124 may include a refractive index n _F . Refractive index n of wedge-shaped feature 118 _B Selectable to improve the viewing angle of the display. For example, a graph8 is a graph showing the intersection of two adjacent wedge-shaped features and the light ray 32 emitted by the electroluminescent element 104 with the side surface 146 of the wedge-shaped feature 118 and the angle θ relative to the normal 148 of the intersecting surface _B Is a schematic diagram of (a). Fig. 9 is a diagram showing θ _B Equal to or greater than theta _C Close-up view of time, θ _C Is the critical angle (theta) at which total reflection occurs _C =arcsine n _B /n _F ). Refractive index n of wedge-shaped feature 118 _B And refractive index n surrounding MRT substrate layer 124 _F Phase difference an (i.e. an=n _B －n _F ) Will produce large reflection values, e.g., θ, at high angles of incidence due to total internal reflection _B >θ _C This is shown in the modeling data of fig. 10. FIG. 10 is a graph of modeled and dimensionless light intensity for several Δn values as a function of viewing angle (θ _V ) The graph is changed and compared with the lambertian distribution. The plurality of wedge-shaped features 118 are arranged in parallel rows, and the wedge angle β, the height to width (H1/W1) aspect ratio between the wedge-shaped feature base and the adjacent sides of the wedge-shaped features, and the trapezoidal cross-sectional shape of the base and the opposing top surfaces protruding toward the plurality of electroluminescent elements all contribute to improved transmittance and viewing angle. The data shows that the refractive index n is made n by selecting the material for the wedge-shaped feature _B Less than the refractive index n of the MRT substrate layer 124 surrounding the wedge-shaped feature 118 _F The viewing angle (increase) can be improved. For example, the viewing angle may be increased to greater than 30 degrees or greater than 40 degrees or greater than 45 degrees. The MRT base layer 124 and/or wedge features 118 may be selected to provide a Δn of about-0.5 to about 0, such as about-0.3 to 0.

Figures 11 and 12 show modeled transmittance and reflectance, respectively, between a cover plate including wedge features (WSF) 118 and a display device including Circular Polarizers (CPs). The data of fig. 11 predicts an increase in transmittance of about 22% for the ambient contrast filter using the wedge feature. FIG. 12 shows that for incoming ambient light at angles of incidence of 0 and 50, the wedge feature display has a greater amount of ambient reflected light, but the display fitted with a circular polarizer is at an angle of incidence θ compared to the WSF display at the same angle of incidence _inc Exhibiting a significantly increased reflected light at 50 °. Light transmittance enhancement of WSF ambient contrast filters allows for less current injection into the electroluminescent displayThe element (e.g., micro LED) gives the same brightness as the circularly polarized cover plate. This provides additional benefits to display devices (e.g., micro LED displays), including, for example, longer display lifetime and reliability. In some embodiments, the ambient contrast filter may have a light transmittance of at least 50%, such as at least 60%, at least 70%, at least 80%, or at least 90%.

Turning now to fig. 13, ace filter layer 114 may include a selectively absorbing layer 150 disposed on MRT base layer 124, for example, between MRT base layer 124 and substrate layer 112. The light absorbing layer 150 may be formed of the same or similar material as the wedge-shaped features 118. Accordingly, the transmittance of the light absorbing layer 150 may be controlled by controlling the density of the light absorbing material disposed at the light absorbing layer 150 and/or the thickness of the light absorbing layer 150 to obtain a predetermined transmittance. For example, the light absorbing layer 150 may contain carbon particles (e.g., carbon black) or other suitable particles and have a density of about 1 wt% to about 20 wt%, such as about 5 wt% to about 15 wt%, about 5 wt% to about 10 wt%, about 5 wt% to about 9 wt%, or about 6 wt% to about 8 wt%. The percentage of carbon black may be about 7.5 weight percent. The material comprising the light absorbing layer 150 may be the same material comprising the wedge-shaped features 118. The thickness 151 of the light absorbing layer 150 can be about 10nm to about 1 micron, such as about 0.1 μm to about 10 μm. As described in more detail below, the particle density and/or thickness of the light absorbing layer 150 may be used to achieve a transmittance through the light absorbing layer 150 of at least about 60%.

Fig. 14 is a natural log (ln) plot of modeled transmittance of light absorbing layer 150 as a function of thickness (in microns) at a wavelength of 550 nm. Fig. 14 plots the linear data intended to be combined. It is shown that the transmittance can be reduced by increasing the thickness of the light absorbing layer 150. Fig. 15 is a graph of the absorbance of the light absorbing layer 150 at a wavelength of 550nm, again as a function of thickness (in microns). Fig. 15 shows that as the light absorption layer thickness increases, the absorption rate increases. This will result in reduced surface reflection and thus a higher ambient contrast ratio for an ambient contrast filter comprising a layer of light absorbing material than for an embodiment without a light absorbing layer. Although the light absorbing layer 150 may cause a slight decrease in the transmittance of the environmental contrast filter 106 compared to an environmental contrast filter having the wedge-shaped features 118 but no light absorbing layer 150, the inclusion of the light absorbing layer 150 may result in an increase in contrast ratio. For example, a contrast ratio of equal to or greater than about 500 may be achieved by including both the wedge-shaped features 118 and the light absorbing layer 150.

The extinction coefficient k of the light absorbing layer 150 may be selected to match a target transmittance, e.g., a transmittance equal to or greater than 60%. The extinction coefficient k is the imaginary part of the complex refractive index (n+ik) and can be varied by selecting the particle density and/or the thickness of the light absorbing layer 150, which can determine the amount of absorption. The extinction coefficient k can be calculated from the following equation, T=e++4 nk/λ) d, where T represents the transmittance, d represents the film thickness, and n is the refractive index (++represents the index). Fig. 16 shows the theoretical prediction of the variation of the light transmittance (or light absorptivity) and its extinction coefficient k with the transmittance T (equal to 1-a, where a represents light absorptivity) for a thin absorbing layer 150 for a layer thickness d (0.1 μm to 10 μm).

The performance impact of the light absorbing layer 150 can be estimated numerically by ray-optic modeling, and the analysis results are shown in fig. 17 to 19. The pitch P1 (spatial period) and k of the wedge-shaped features 118 are one of the geometric parameters studied. For this analysis, it is assumed that the back-plate substrate 102 has a reflectivity of 10% of the incident ambient light. The target transmittance and reflectance of the ambient contrast filter were 60% and 70%, respectively. FIG. 17 is a graph of transmittance as a function of pitch P1 for different k values and wedge feature heights H1 μm. The data shows that as k increases (light absorbing layer 150 becomes more absorptive), for example greater than 0.05, the transmittance decreases (since the reflectance is inversely proportional to the environmental contrast ratio (ACR), the light transmittance is inversely related to ACR). ACR is I1+I _o /(I _amb －R _amb ) Calculation of I _o Is the intensity of light emitted by the electroluminescent element in the "on" state, I _amb Is the intensity of ambient light, R _amb Is the reflectance of ambient light from the back plate substrate 102. To meet the transmittance and reflectance requirements, k may be selected to be about 0.05 to about 1. The choice of k may also depend on the thickness of the light absorbing layer 150.

Further, the height H1 of the wedge-shaped feature 118 is estimated to be about 50 μm to about 70 μm. FIG. 18 is a plot of modeled reflectance versus pitch for different k values and wedge feature heights H1 50 μm, and FIG. 19 is a plot of modeled reflectance versus pitch for different k values and wedge feature heights H1 70 μm. The data shows that as k increases, the reflectivity decreases, but conversely, as pitch increases, the reflectivity increases. Tests have shown that reducing the wedge feature height H1 can make the process of patterning the recesses defining the wedge feature geometry and filling the recesses with light absorbing material more reliable. These characteristics can be used to find a suitable trade-off between pitch, wedge feature height and k to minimize reflectivity. Surprisingly, in both models, data with a larger k value (e.g., k=0.5) shows low reflection sensitivity for both pitch and height, with a trend being evident with smaller k values. I.e., the data shows that the change in reflectivity due to the change in pitch and height of the wedge-shaped features is small at higher values of k.

Since the emission profile helps determine the viewing angle of the electroluminescent display, the angular emission profile of the LED light emitted by the display (e.g., by the ambient contrast filter 106) in the presence of the light absorbing layer 150 is also analyzed. The examples of h1=50 μm (fig. 18) and 70 μm (fig. 17 and 19) were again estimated and compared with the environmental contrast filter without the light absorbing layer 150. Fig. 20 and 21 present modeled and dimensionless intensity variations with the emission angle of the electroluminescent element. This analysis demonstrates that the presence of the light absorbing layer 150 provides a greater viewing angle than the ambient contrast filter without the light absorbing layer 150, except for the wedge-shaped features 118. The data shows that an ambient contrast filter comprising both wedge features 118 and light absorbing layer 150 exhibits an extinction ratio of about 0.01 to about 0.1, providing an ACR in excess of 500 in a micro LED display.

Fig. 22 is a graph showing modeled ambient contrast ratio as a function of total reflection. The data are presented in terms of environmental contrast ratio (ACR) predictions, nits, and achievable ACR at different ambient illumination levels. For example, axis 153 represents a display device comprising a plurality of wedge-shaped features and the light absorbing layer 150, while axis 155 represents the same display with wedge-shaped features 118 but without light absorbing layer 150. In contrast, axis 157 represents the same display without wedge feature 118 and without light absorbing layer 150. The reflection amount of ambient light from the back plate substrate is assumed to be 10%. The data shows that an ACR of greater than 500 can be achieved with a display device that incorporates the light absorbing wedge feature 118 in combination with an ambient contrast filter of the light absorbing layer 150.

Fig. 23 illustrates yet another embodiment of an environmental contrast filter 106, where the environmental contrast filter may include alternating wedge-shaped feature columns of different heights and different widths. Fig. 23 depicts a partial cross-sectional view of an environmental contrast filter 106 including a substrate layer 112 and an ACE layer 114, the ACE layer 114 including a plurality of wedge-shaped features buried therein: a first plurality of wedge features 118 and a second plurality of wedge features 160. The first plurality of wedge-shaped features 118 may be arranged in an elongated wedge-shaped feature column having a maximum width W1 and a height H1 as previously described. The second plurality of wedge-shaped features 160 may also be arranged in parallel rows of elongated wedge-shaped features and have a maximum width W2 at the base of the wedge-shaped features 160 and a height H2, wherein the height H2 is estimated base-to-end (furthest from the substrate layer 112) of the wedge-shaped features 160 in the same manner as the wedge-shaped features 118. The second plurality of wedge features 160 may alternate with the first plurality of wedge features 118. The height H2 of the wedge features 160 of the second plurality of wedge features may be less than the height H1 of the wedge features 118 of the first plurality of wedge features. The maximum width W2 of the wedge-shaped features 160 of the second plurality of wedge-shaped features may be less than the maximum width W1 of the wedge-shaped features 118 of the first plurality of wedge-shaped features. Accordingly, the height H2 and the maximum width W2 may be less than the height H1 and the maximum width W1, respectively, of the wedge-shaped features 118 of the first plurality of wedge-shaped features. The aspect ratio, defined in terms of H1/W1, may be equal to or greater than about 3, such as about 3 to about 6.

With continued reference to fig. 23, the first plurality of wedge-shaped features 118 may be periodically spaced by a pitch P1, the pitch P1 defining the separation distance between adjacent wedge-shaped features, which is the distance from the center of a wedge-shaped feature 118 to the center of an adjacent wedge-shaped feature 118. The pitch P1 of the first plurality of wedge-shaped features may be about 50 μm to about 200 μm, for example about 60 μm to about 150 μm, about 60 μm to about 100 μm, or about 60 μm to about 90 μm. In addition, the wedge features 160 may also be periodically spaced by a pitch P2, the pitch P2 defining the separation distance between adjacent wedge features 160, which is the distance from the center of one wedge feature 160 to the center of another adjacent wedge feature 160. Each wedge feature 160 may be positioned at a midpoint between adjacent wedge features 118 such that P2 is equal to P1. That is, the second plurality of wedge-shaped features 160 may be equally spaced between the first plurality of wedge-shaped features 118. The distance between the center of the wedge feature 118 and the adjacent wedge feature 160 may be (P1)/2.

Fig. 24 and 25 present modeling data showing the transmittance (fig. 24) and reflectance (fig. 25) as a function of the pitch P1, and assume p2=p1. The data shows a comparison of a display having a single plurality of wedge features with a display having two pluralities of wedge features, wherein the height of the second plurality of wedge features is different from the height of the first plurality of wedge features. The data further shows that a display with two pluralities of wedge features each having two different heights and a larger pitch P1 (e.g., 90 μm) can have optical performance similar to a display with a single plurality of wedge features and a short pitch (e.g., 60 μm) having the same height while maintaining a transmittance of more than 60% and a reflectance of less than 8%. While adding the second plurality of wedge-shaped features may result in a denser overall wedge-shaped feature pattern from the perspective of the viewer, the additional plurality of wedge-shaped features with low aspect ratios may not significantly degrade the viewing angle of the human viewer, but may also provide absorption geometry that may contribute to ambient light suppression.

Fig. 26 and 27 present modeled data for displays having two pluralities of wedge-shaped features of different heights, and show that the transmittance (fig. 26) and reflectance (fig. 27) vary with height H2. When H2 is 10 μm to 70 μm, the result is different from the pitch change observation trend. However, the effect of H2 is not so great, and assuming that the light absorbing material is highly absorptive, including for example an extinction coefficient k greater than 0.1, the transmittance changes by less than 10% and the reflectance changes by less than 1%.

The data show that a higher height H2 results in greater transmittance and less reflectance. As the surface area causing total internal reflection becomes wider, the transmittance increases with an increase in the height H2. However, the reflectivity decreases as the aspect ratio of the second plurality of wedge-shaped features increases.

FIG. 28 is a modeled angular emission profile of light emitted by an electroluminescent element having a single (first) plurality of wedge-shaped features and a display having two (first and second) pluralities of wedge-shaped features. Fig. 28 shows the light intensity of the emitted light as a function of viewing angle. In this comparison, the pitch (P1, P2) of a display with a single plurality of wedge features and a display with two pluralities of wedge features are 60 μm and 90 μm, respectively. Data shows that displays with two multiple wedge features of different aspect ratios can have improved viewing angles without sacrificing basic optical performance compared to displays with a single multiple wedge feature.

The environmental contrast filter 106 may be used without the 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, including a backplane substrate 102 including a plurality of electroluminescent elements 104 deposited thereon and an environmental contrast filter 106 disposed over the backplane substrate 102. The electroluminescent elements 104 comprise individual pixel elements of an image pixel and thus may be configured to display different colors, such as red (R), green (G), and blue (B). However, in the embodiment of fig. 29, the environmental contrast filter 106 lacks a substrate layer 112, such as a glass substrate layer. Thus, in various embodiments, the environmental contrast filter 106 may be formed from the ACE layer 114 including the support layer 125, the MRT base layer 124, the wedge features 118 (and the optional wedge features 160), and the light absorbing layer 150. ACE layer 114 may be directly attached to back substrate 102 and/or electroluminescent element 104 using adhesive layer 122 so that there is no air gap between electroluminescent element 104 and environmental contrast filter 106. The bonding layer 122 may be, for example, an optically clear adhesive. The environmental contrast filter 106 may include at least one AR layer 116, such as the AR layer 116 disposed atop the light absorbing layer 150.

Advantageously, the environmental contrast filter, which does not include a glass substrate layer, can be applied directly to an electroluminescent display panel, such as the backplane substrate 102, so that the display device is much thinner than embodiments employing a glass substrate layer. Further, display panels comprising glass substrate layers are typically manufactured by forming a plurality of display panels on a single backplane "motherboard" and attaching a cover plate comprising glass substrate layers to the backplane before cutting the motherboard into individual display panels. This not only requires cutting the back plate, but also the glass substrate layer, so that the cutting difficulty is increased and the cost of the display panel is increased. Eliminating the glass substrate layer may make it easier and less costly to cut the display panel from a larger display motherboard. In addition, eliminating the glass substrate layer may reduce transportation and installation costs. Due to the small size and light weight, display panels employing thin film environments without glass substrate layers are easier to handle than optical filters. As for film-type solutions, fabrication can be accomplished in a roll-to-roll process, from patterning the MRT substrate layer to filling the recesses with light absorbing material, to low reflection patterning, is a process suitable for mass production.

Thus, an apparatus 200 for forming the environmental contrast filter 106 is depicted in FIGS. 30-31. Turning first to fig. 30, the apparatus 200 may include a first step processing apparatus 202 configured to fabricate an MRT film 120 including an MRT base layer 124 and a support layer 125. The first step processing apparatus 202 includes a patterned roll 204, a first support roll 206, a second support roll 208, a first dispensing nozzle 210, and a first curing apparatus 212. The patterned roll 204 is an elongated roll having a generally circular cross-section and includes a plurality of protrusions 214 (e.g., teeth) disposed about a first circumferential surface 216 of the patterned roll and extending along the length of the patterned roll, the protrusions 214 corresponding to the wedge features 118. The plurality of protrusions 214 may be periodically spaced. For example, each protrusion 214 may be equally spaced from adjacent protrusions around the first circumferential surface 216 such that the angular separation between the protrusions is equal. For purposes of illustration and not limitation, if patterned roll 204 has 60 protrusions, 60 protrusions may be spaced every 1 ° angle around the circumferential surface of the patterned roll. If the patterned roll 204 has 120 protrusions, the 120 protrusions may be spaced every 0.5 °. It should be appreciated that in practice, the inter-tab spacing is on the order of microns, corresponding to, for example, the predetermined period P1 for the fabrication of the wedge-shaped features 118. I.e., a period suitable for fabricating the wedge-shaped features 118 and/or 160 is about 40 μm to about 500 μm, such as about 50 μm to about 200 μm, for example about 60 μm to about 150 μm, about 60 μm to about 100 μm, or about 60 μm to about 90 μm, including all ranges and subranges therebetween.

However, the protrusions 108 may be spaced differently such that the angular separation between one pair of adjacent protrusions is different from the angular separation between the other pair of adjacent protrusions. For example, the angular separation may increase from one pair of abutment projections to the next pair of abutment projections relative to a predetermined direction of rotation about the patterned roll. Also, by way of example, and not limitation, four sequentially arranged protrusions may be considered: the first protrusion, the second protrusion adjacent to the first protrusion, the third protrusion adjacent to the second protrusion, and the fourth protrusion adjacent to the third protrusion. The angular distance between the first projection and the adjacent second projection may be 1 deg., for example, moving in a clockwise direction. The angular distance between the second protrusion and the third protrusion may be 1.01 °. The angular separation between the third and fourth protrusions may be 1.02 deg., and so on, with each protrusion increasing 0.01 deg. from the angular separation of the front protrusion. Of course, when the first and second protrusions are reached again, the angular distance between the adjacent protrusions returns to 1 °. It should be appreciated that patterned roll 204 may include a sub-pattern of protrusions wherein the first protrusion is repeated, for example, every 10 protrusions, when returned. In fact, any predetermined pattern of protrusions, including any angular or circumferential distance between protrusions, may be provided as desired or required to produce a similar wedge-shaped feature pattern.

The patterned roll 204 includes and is rotatable about a first axis of rotation 218. The protrusions 214 may extend along the length of the patterned roll parallel to each other. For example, each tab may be an elongated structure that extends a height H1 above the first circumferential surface 216. The tab 214 may be parallel to the first axis of rotation 218, or the tab 214 may be helically arranged about the first axis of rotation 218 of the first circumferential surface 216. In some embodiments, the height of the tab 214 relative to the first circumferential surface 216 along a normal to the first circumferential surface 216 may be different. For example, as previously described, two different heights H1 and H2 may be provided, which correspond to the heights of the wedge-shaped features 118 and 160, respectively, although additional numbers of heights, e.g., greater than two heights, may also be provided corresponding to other pluralities of wedge-shaped features.

The first support roller 206 includes a second circumferential surface 220 disposed thereabout and is rotatable about a second axis of rotation 222. The second circumferential surface 220 may be a smooth surface. The second axis of rotation 222 may be parallel to the first axis of rotation 218. The second circumferential surface 220 may be spaced a first predetermined distance 224 from the first circumferential surface 216. I.e. the first circumferential surface 216 is separated from the second circumferential surface 220 by a first gap 226. The first predetermined distance 224 is greater than the maximum height of the tab 214, e.g., greater than H1.

The second support roller 208 includes a third circumferential surface 228 disposed about and rotatable about a third axis of rotation 230. Like the first backup roll 206, the third circumferential surface 228 may be a smooth surface. The third axis of rotation 230 may be parallel to the first axis of rotation 218. The third circumferential surface 228 may be spaced a second predetermined distance 232 from the first circumferential surface 216. I.e., the first circumferential surface 216 is separated from the third circumferential surface 228 by a second gap 234. The second predetermined distance 232 is greater than the maximum height of the tab 214, e.g., greater than H1. The first rotation axis 218, the second rotation axis 222, and the third rotation axis 230 may be coplanar, i.e., located in the same plane.

The first dispensing nozzle 210 is configured to dispense the matrix material 236 into the first gap 226 between the patterned roll 204 and the first support roll 206. Further, the first curing apparatus 212 is configured to cure the matrix material 236 to form the MRT base layer 124. The first curing apparatus 212 includes a curing device 238, such as a UV illumination device, configured to direct first UV light 240 into the first gap 226.

As shown in fig. 30, a support layer 125 (e.g., a preformed polymer film, such as PET) is directed to the first step processing equipment 202 over the first support roller 206 and into the first gap 226. The support layer 125 includes a first major surface 242 and a second major surface 244 opposite the first major surface 242. With the second major surface 244 of the support layer 125 in contact and supported by the second circumferential surface 220 of the first support roller 206, the liquid matrix material 236 may be dispensed from above the first gap 226 into the first gap 226 and deposited between the first major surface 242 of the support layer 125 and the first circumferential surface 216 of the patterned roller 204 by the first dispensing nozzle 210. The matrix material 236 may be, for example, a polymer resin, such as a UV curable acrylate monomer, a multifunctional acrylate oligomer, a photoinitiator, and any desired additional additives. The radical polymerization photoinitiator for the base resin may be, for example, diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide, α -hydroxyphenylketone, 2-dimethoxy-2-phenylacetophenone, triarylphosphine oxide, or bisacylphosphine oxide.

The viscosity of the matrix material 236 may be about 50 millipascal-seconds (mPa-s) to about 1000 mPa-s, such as about 75 mPa-s to about 300 mPa-s, when the matrix material is dispensed from the first dispensing nozzle 210. The patterned roll 204 and the first support roll 206 rotate and the protrusions 214 move away from the matrix material 236 in the first gap 226. For example, in the embodiment shown in fig. 30, the process is run from right to left, wherein patterned roll 204 is shown rotating in a clockwise direction and first support roll 206 is rotating in a counter-clockwise direction. As the liquid matrix material 236 adhering to the first major surface 242 of the support layer 125 exits the first gap 226, the matrix material is cured by the first curing apparatus 212 disposed below the first gap 226 and/or the patterned roll 204. For example, the matrix material 236 may be an Ultraviolet (UV) light curable polymeric material. Thus, the first UV illumination device 238 emits first UV light 240 upward to the first gap 226 and/or the underside of the patterned roll 204 and then through the support layer 125, thereby curing the matrix material 236 into an MRT film 120 comprising the support layer 125 and the MRT base layer 124, the MRT film 120 comprising a plurality of recesses 246 mimicking the protrusions 214. I.e., the recess 246 is the negative of the protrusion 214. The refractive index of the cured MRT base layer 124 may be between about 1.45 and about 1.65.

As further shown in fig. 30, as the patterned roll 204 rotates in a clockwise direction, the MRT film 120 travels around and under the first circumferential surface 216 and the protrusions 214 engage the recesses 246. The MRT film 120 is then wound over the second support roller 208 such that the second major surface 244 of the support layer 125 contacts the third circumferential surface 228 of the second support roller 208 and the recesses 246 face outwardly away from the third circumferential surface 228. Although not shown, the MRT film 120 may be collected, rolled up and stored downstream of the second support roller 208 for later use or provided to a second apparatus that performs a second process step.

Thus, referring now to fig. 31, the apparatus 200 may further comprise a second step processing apparatus 250. The second stage treatment apparatus 250 includes an application roller 302, a third support roller 304, a fourth support roller 306, a second dispensing nozzle 308, a second curing apparatus 310, and an optional third curing apparatus 312.

The application roller 302 includes a fourth circumferential surface 314 disposed for rotation about a fourth axis of rotation 316. Unlike patterned roll 204, fourth circumferential surface 314 may be a smooth surface.

The third support roller 304 includes a fifth circumferential surface 318 disposed for rotation about a fifth axis of rotation 320. The fifth circumferential surface 318 may be a smooth surface. In an embodiment, the fifth axis of rotation 320 is parallel to the fourth axis of rotation 316. Fifth circumferential surface 318 may be spaced a third predetermined distance 322 from fourth circumferential surface 314. I.e., fourth circumferential surface 314 is separated from fifth circumferential surface 318 by third gap 324.

The fourth support roller 306 includes a sixth circumferential surface 326 disposed for rotation about a sixth axis of rotation 328. The sixth circumferential surface 326 may be a smooth surface. In an embodiment, the sixth axis of rotation 328 is parallel to the fourth axis of rotation 316. The sixth circumferential surface 326 may be spaced a fourth predetermined distance 330 from the fourth circumferential surface 314. I.e., sixth circumferential surface 326 is separated from fourth circumferential surface 314 by fourth gap 332.

As shown in fig. 31, the MRT film 120 is guided by the third support roller 304 into a third gap 324, wherein the MRT film 120 occupies the third gap 324 between the third support roller 304 and the application roller 302 (note that the support layer 125 is not shown separately, but is included). For example, in the embodiment shown in fig. 32, the process is a right-to-left operation in which the application roller 302 rotates in a clockwise direction and the third support roller 304 rotates in a counterclockwise direction. The MRT film 120 advances past the third support roller 304 with the recesses 246 facing outwardly away from the fifth circumferential surface 318, and then into the third gap 324. When the MRT film 120 enters the third gap 324 between the application roller 302 and the third support roller 304, the recess 246 faces the fourth circumferential surface 314 of the 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 pushed into recess 246 by application roller 302. The light absorbing material 334 may be, for example, a polymeric material including a light absorbing additive, such as carbon black, wherein the carbon black is dispersed in the polymeric material. The carbon black particles may have a particle size of about 10 nanometers (nm) to about 500nm, such as about 10nm to about 400nm, such as about 10nm to about 300nm or about 10nm to about 200nm. The carbon black particles may be present in the light absorbing material in an amount of from about 5 wt% to about 10 wt%, for example from about 6 wt% to about 8 wt%. In some embodiments, the carbon black particles may be present in the light absorbing material in an amount of about 7.5 wt.%. The viscosity of the light absorbing material dispensed by the second dispensing nozzle 308 may be from about 75 mPa-s to about 300 mPa-s.

The second curing device 310 at least partially cures the light absorbing material 334 to form the ACE layer 114. For example, the light absorbing material 334 may be an Ultraviolet (UV) light curable polymeric material. Accordingly, the second curing apparatus 310 may include a UV light source 338, the UV light source 338 being disposed below the third gap 324 and/or the application roller 302 and configured to direct the second UV light 340 into the third gap 324 and/or toward the ACE layer 114 on the application roller 302. Since the first curing of the light absorbing material 334 occurs through the back side (opposite side of the recess 246) of the MRT film 120, the thickness of the MRT film 120 may prevent curing. Thus, an optional third curing device 312 may be provided above the fourth gap 332 and/or above the fourth backup roll 306. The third curing apparatus 312 includes a third UV light source 346 configured to direct third UV light 348 to the MRT film 120 and the light absorbing material 334. For example, as the MRT film 120 advances around the application roller 302 (e.g., the bottom of the application roller 302), the MRT film 120 is guided through the fourth gap 332 and over the fourth support roller 306 as the fourth support roller 306 rotates in a counterclockwise direction. In this configuration, the recesses 246 now filled with at least partially cured light absorbing material 334 face outwardly away from the sixth circumferential surface 326 such that the light absorbing material 334 can be directly illuminated by the third UV light 348 to provide the predetermined cure. The refractive index difference between the cured MRT film 120 (e.g., the MRT base layer 124) and the cured light absorbing material may be from 0 to about 0.08, such as from 0 to about 0.06, such as from about 0 to about 0.05, from about 0 to about 0.04, or from about 0 to about 0.03. For example, the refractive index of the cured light absorbing material may be about 1.45 to about 1.51. The resulting ambient contrast filter 106 may then be used to fabricate the ambient contrast enhanced electroluminescent display described herein.

Although not shown, additional second and fifth support rollers and third dispensing nozzles may be provided downstream of the fourth support roller 306 and fourth curing apparatus, wherein additional rollers, dispensing apparatus, and curing apparatus may be used to deposit the light absorbing layer 150 to the ACE layer 114. The AR layer 116 may also be added. However, with the third support roller 304 and the application roller 302, the light absorbing layer 150 and the recess 246 can be applied simultaneously by adjusting the distance 322 between the fourth circumferential surface 314 and the fifth circumferential surface 318.

The apparatus described above with respect to fig. 30-31 provides for the formation of the recessed MRT film 120 and subsequent filling of the MRT film recesses with light absorbing material to be performed as a separate, discrete process. However, these processes are not necessarily performed separately. That is, as described above, the MRT film 120 may be stored prior to filling with the light absorbing material. However, the steps described in fig. 30-31 may be performed sequentially one after the other in an in-line process.

Thus, fig. 32 depicts an in-line process for forming ACE layer 114. For purposes of illustration and not limitation, the processing device of fig. 32 is arranged from right to left.

According to fig. 33, an apparatus 400 for in-line manufacturing of environmental contrast filter 106 is schematically illustrated. The apparatus 400 includes a first support roll 402, a first dispensing nozzle 404, a first curing device 406, a first patterned roll 408, a second support roll 410, an application roll 412, a second dispensing nozzle 414, a second curing device 416, and a third support roll 418. The apparatus 400 may further include a third dispensing nozzle 420, a second patterned roll 422, a third curing device 424, and a fourth backup roll 426.

As shown in fig. 31, the first patterned roll 408 is an elongated roll that includes a plurality of protrusions 430 (e.g., teeth) disposed about a first circumferential surface 432 of the first patterned roll 408 and extending along a length of the first patterned roll. The plurality of projections 430 may be periodically spaced between adjacent projections or groups of projections. For example, like patterned roll 204, each protrusion 430 of first patterned roll 408 may be equally spaced from an adjacent protrusion such that the angular spacing between protrusions is equal. However, the projections 430 may be spaced differently such that the angular separation between one pair of adjacent projections is different from the angular separation between the other pair of adjacent projections. The protrusions 430 may be arranged in any desired pattern, including any desired angular or circumferential distance between the protrusions.

The first patterned roll 408 can rotate about a first axis of rotation 434. In various embodiments, the protrusions 430 may extend along the length of the first patterned roll 408 that are parallel to each other. For example, each tab 430 may be an elongated structure extending outwardly from the first circumferential surface 432 a predetermined height H1. The tab 430 may extend parallel to the first axis of rotation 434. Alternatively, the protrusion 430 may be spirally arranged on the first circumferential surface 432. The protrusions 430 may be arranged as desired such that the distance between adjacent wedge-shaped features is made from about 40 μm to about 500 μm, such as from about 50 μm to about 200 μm, for example from about 60 μm to about 150 μm, from about 60 μm to about 100 μm, or from about 60 μm to about 90 μm, including all ranges and subranges therebetween. The height of the tab 430 relative to the first circumferential surface 432 along the normal to the first circumferential surface 432 may be different. For example, some of the protrusions may have a height H2 different from H1, e.g., less than H1.

The first support roller 402 is an elongated roller comprising a second circumferential surface 436 and is rotatable about a second axis of rotation 438. The second circumferential surface 436 may be a smooth surface. The second axis of rotation 438 may extend parallel to the first axis of rotation 434. The second circumferential surface 436 may be spaced a first predetermined distance 440 from the first circumferential surface 432. I.e. the first circumferential surface 432 is separated from the second circumferential surface 436 by a first gap 442. The first predetermined distance 440 may be equal to or greater than the maximum height of the protrusion 430.

The second support roller 410 is an elongated roller comprising a third circumferential surface 444 and is rotatable about a third axis of rotation 446. The third circumferential surface 444 may be a smooth surface. In an embodiment, the third axis of rotation 446 may extend parallel to the first axis of rotation 434. The third circumferential surface 444 may be spaced from the first circumferential surface 432 by a second predetermined distance 448. I.e. the first circumferential surface 432 is separated from the third circumferential surface 444 by a second gap 450. The second predetermined distance 448 may be equal to or greater than the maximum height of the protrusion 430. The first rotation axis 434, the second rotation axis 438, and the third rotation axis 446 may be coplanar.

The first dispensing nozzle 404 is configured to dispense the matrix material 452 into the first gap 442 between the first patterned roll 408 and the first support roll 402. For example, the dispensing nozzle 404 may be in communication with a source of liquid matrix material 452 and positioned above the first gap 442. The matrix material 452 may be pumped to the first dispensing nozzle 404.

As shown in fig. 33, as the support layer 125 is fed into the first gap 442, liquid matrix material 452 is also dispensed from above the first gap 442 into the first gap 442 by the first dispensing nozzle 404, wherein the matrix material 452 occupies the first gap 442 between the first patterned roll 408 and the first support roll 402, and more particularly, between the support layer 125 and the first patterned roll 408. As the first patterned roll 408 and the first support roll 402 rotate, the protrusions 214 move away from the matrix material 452 in the first gap 442. For example, as shown in fig. 33, the process is running from right to left, in which the first patterning roller 408 rotates in a clockwise direction and the first support roller 402 rotates in a counterclockwise direction. As the matrix material 452 exits the first gap 442, the matrix material 452 is cured by a first curing device 406 disposed below the first gap 442 and/or the first patterned roll 408 to become an MRT base layer 124, the MRT base layer 124 engaging the support layer 125 to form the MRT film 120. The matrix material 452 may be an Ultraviolet (UV) light curable polymeric material. Thus, the first curing device 406 may include a UV illumination device 454, the UV illumination device 454 configured to emit first UV light 456 upward into the first gap 442 and/or toward the support layer 125 under the first patterned roll 408, thereby curing the matrix material 452 into the MRT film 120 including the MRT base layer 124 and the support layer 125, the MRT base layer 124 including a plurality of recesses 460 mimicking the protrusions 430. The recess 460 is the negative of the protrusion 430.

As further shown in fig. 32, as the first patterned roll 408 rotates in a clockwise direction, the MRT film 120 travels under the first patterned roll 408 and the protrusions 430 engage the recesses 460. The MRT film 120 is then directed to the second gap 450 and wound over the second support roller 410 with the recess 460 facing outwardly away from the third circumferential surface 444.

The third circumferential surface 444 of the second support roller 410 is separated from the fourth circumferential surface 462 of the application roller 412 by a predetermined distance 464. I.e., the third circumferential surface 444 of the second backup roll 410 is separated from the fourth circumferential surface 462 of the applicator roll 412 by a third gap 466. The MRT film 120 travels over the third circumferential surface 444 of the second support roller 410 and is directed to the third gap 466. The MRT film 120 advances past the second support roller 410 and the recess 460 faces outwardly away from the third circumferential surface 444. When the MRT film 120 enters the third gap 466 between the application roller 412 and the second support roller 410, the recess 460 faces the fourth circumferential surface 462 of the application roller 412. The liquid light absorbing material 468 is dispensed into the third gap 466 by the second dispensing nozzle 414 and pushed into the recess 460 by the application roller 412. The predetermined distance 464 may be adjusted so that in addition to filling the recess 460 with the light absorbing material 468, the light absorbing material may also form a continuous layer over the MRT film 120. As the MRT film 120 exits the third gap 466, the light absorbing material 468 (including the light absorbing layer 150 (if applied)) is cured by the second curing apparatus 416 to form the wedge-shaped features 118 (and/or the wedge-shaped features 160 and/or the light absorbing layer 150). For example, the light absorbing material 468 may be an Ultraviolet (UV) light curable polymer material.

The third support roller 418 is rotatable about a fifth axis of rotation 478. The fifth circumferential surface 480 may be a smooth surface. Fifth axis of rotation 478 may be parallel to first axis of rotation 434. As shown in fig. 32, ACE layer 114 spans third support roll 418 and may be collected from third support roll 418. For example, in some embodiments, the ACE layer 114 comprising at least partially cured light absorbing material may be directed to a downstream device (not shown) configured to process (e.g., roll up) the ACE layer 114 for later use. However, additional layers may be added to ACE layer 114. For example, the apparatus 400 may further include a second patterned roll 422 rotatable about a sixth circumferential surface 482, the sixth circumferential surface 482 being rotatable about a sixth axis of rotation 484. The sixth circumferential surface 482 may be spaced a third predetermined distance 486 from the fifth circumferential surface 480. I.e., sixth circumferential surface 482 is separated from fifth circumferential surface 480 by fourth gap 488. As ACE layer 114 exits fifth circumferential surface 480 of third support roller 418, ACE layer 114 is directed into fourth gap 488. The third dispensing nozzle 420 may be arranged to direct the flow of polymer resin 490 into the fourth gap 488 between the second patterned roll 422 and the ACE layer 114. The polymer resin 490 may beIncluding, for example, functionalized acrylates such as 1, 6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), trimethylol propane triacrylate (TMPTA) or functionalized methyl acrylates such as trimethylol propane triacrylate (TMPTMA) or any combination of the above. In some cases, sixth circumferential surface 482 is a textured surface, such as a roughened surface having a predetermined roughness. Referring to fig. 32, ace layer 114 is oriented such that polymer resin 490 contacts wedge feature 118 (and/or wedge feature 160) or light absorbing layer 150 (if applied), thereby forming AR layer 116. As the polymer resin 490 contacts the sixth circumferential surface 482, the sixth circumferential surface 482 presents a texture that will print onto the outer facing surface of the polymer resin. The third curing apparatus 424 is positioned below the fourth gap 488 and/or the second patterned roll 422 and includes a UV illuminator 494 configured to direct third UV light 496 through the ACE layer 114, at least partially curing the polymer resin 490 to form the environmental contrast filter 106. In some cases, the AR layer 116 may be an inorganic layer, such as SiO ₂ . The AR layer 490 should have a transparency of at least 90% at the applied thickness.

It will be appreciated from the present disclosure that the various rollers of apparatus 400 may be interchanged such that the different layer arrangement of environmental contrast filter 106 is different from the arrangement provided by the embodiment of fig. 33. In other words, various patterned rolls, dispensing nozzles, and curing equipment may be suitably arranged to produce environmental contrast filters having different numbers of layers and sequences.

Examples of non-limiting display devices with different layer arrangements of ambient contrast filters 106 can be seen in fig. 33-36. Fig. 33 shows an exemplary display device 100 comprising a backplane substrate 102, the backplane substrate 102 comprising a plurality of electroluminescent elements 104 disposed thereon, the display device 100 comprising an ambient contrast filter 106 disposed atop the backplane substrate 102. The environmental contrast filter 106 includes, from bottom to top, an ACE layer 114 including a support layer 125 and an MRT base layer 124, the MRT base layer 124 including a plurality of wedge feature 118 layers 124 disposed therein. The light absorbing layer 150 is disposed atop the MRT base layer 124. The environmental contrast filter 106 may be attached to the backplate substrate 102 by an adhesive layer 122. In the embodiment of fig. 33, the environmental contrast filter 106 does not include a glass substrate layer (e.g., glass substrate layer 112), and the environmental contrast filter is directly attached to the backplane substrate 102 and/or the electroluminescent element 104. I.e. the display device of fig. 33 does not comprise a glass cover plate over the back plate and the electroluminescent element.

Fig. 34 shows another exemplary display device 100 including a backplane substrate 102, the backplane substrate 102 including a plurality of electroluminescent elements 104 disposed thereon, the display device 100 including an environmental contrast filter 106 disposed atop the backplane substrate 102. The environmental contrast filter 106 of fig. 35 is similar to the environmental contrast filter 106 of fig. 34 except that the environmental contrast filter 106 of fig. 34 further includes an anti-reflective layer atop the light absorbing layer 150. The environmental contrast filter 106 of fig. 34 may be attached to the backplate substrate 102 by an adhesive layer 122. Similar to the display device of fig. 33, the environmental contrast filter 106 of fig. 34 does not include a glass substrate layer, and the environmental contrast filter is directly attached to the back plate substrate 102 and/or the electroluminescent element 104. I.e. the display device of fig. 35 does not comprise a glass cover plate over the back plate and the electroluminescent element.

Fig. 35 shows yet another exemplary display device 100 comprising a backplane substrate 102, the backplane substrate 102 comprising a plurality of electroluminescent elements 104 disposed thereon, the display device 100 comprising an ambient contrast filter 106 disposed atop the backplane substrate 102. The environmental contrast filter 106 of fig. 35 includes, from bottom to top, a light absorbing layer 150, an MRT base layer including a plurality of wedge-shaped features 118 disposed therein, and a support layer 125 disposed atop the MRT base layer. The environmental contrast filter 106 of fig. 35 may be attached to the backplate substrate 102 by an adhesive layer 122. Similar to the display devices of fig. 33 and 34, the environmental contrast filter 106 of fig. 35 does not include a glass substrate layer, and the environmental contrast filter is directly attached to the back-plane substrate 102 and/or the electroluminescent element 104. I.e. the display device of fig. 35 does not comprise a glass cover plate over the back plate and the electroluminescent element.

Fig. 36 shows yet another exemplary display device 100 comprising a backplane substrate 102, the backplane substrate 102 comprising a plurality of electroluminescent elements 104 disposed thereon, the display device 100 comprising an ambient contrast filter 106 disposed atop the backplane substrate 102. The environmental contrast filter 106 of fig. 36 includes, from bottom to top, an AR layer 116, a support layer 125, an MRT base layer including a plurality of wedge-shaped features 118 disposed therein, a light absorbing layer 150, a second AR layer 116 disposed atop the light absorbing layer, and a support layer 125 disposed atop the MRT base layer. The environmental contrast filter 106 of fig. 36 may be attached to the backplate substrate 102 by an adhesive layer 122. Similar to the display devices of fig. 33-35, the environmental contrast filter 106 of fig. 36 does not include a glass substrate layer, and the environmental contrast filter is directly attached to the back-plane substrate 102 and/or the electroluminescent element 104. I.e. the display device of fig. 36 does not comprise a glass cover plate over the back plate and the electroluminescent element.

Fig. 37 is a diagram showing several optical characteristics of the structures shown in fig. 33 to 36. Transmittance (T) is measured with a spectrometer and ACR (environmental contrast ratio) is measured using a plasma display panel according to IEC 62341-6-2. T and ACR can be adjusted by changing the structure and material selection. The data shows that the AR layer on top of the wedge-shaped features shows little increase in transmittance and has ACR-like properties compared to the AR-free example. On the other hand, the AR layer disposed on the support layer side showed light transmittance of 43.6%, like the no AR example. However, ACR increases to 140. It is believed that the percent transmission is still the same or even lower than the AR-free example because the wedge-shaped feature pattern is reversed in orientation, resulting in a decrease in transmission, with the bottom side light entering being reduced by the reversal. The double-sided AR structure shows the highest transmittance among the four examples, and the ACR level is similar to the first and second example.

Those skilled in the art will appreciate that various modifications and changes can be made to the embodiments of the disclosure without departing from the spirit and scope thereof. It is therefore intended that the present disclosure cover all modifications and variations as fall within the scope of the appended claims and their equivalents.

Claims

1. An optical display device comprising:

a backplane substrate comprising a plurality of electroluminescent elements deposited thereon in parallel rows, each row of electroluminescent elements comprising a pair of alignment axes;

an environmental contrast filter positioned over the back plate substrate, the environmental contrast filter comprising a polymeric support layer and a microreplicated film base layer disposed on the polymeric support layer, the microreplicated film base layer comprising a plurality of light absorbing wedge features arranged in parallel rows, each light absorbing wedge feature comprising a longitudinal axis; and is also provided with

Wherein the environmental contrast filter does not include a glass layer.

2. The optical display device of claim 1, wherein the environmental contrast filter further comprises a light absorbing layer disposed on the microreplicated film base layer.

3. The optical display device of claim 2, wherein the light absorbing layer has a thickness of about 10nm to about 1 μm.

4. The optical display device of claim 1, wherein the plurality of wedge-shaped features have a height H1 of about 10 μιη to about 100 μιη.

5. The optical display device of claim 4, wherein the H1 is about 10 μιη to about 40 μιη.

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 of about 5 μιη to about 15 μιη.

7. The optical display device of claim 6, wherein the H1/W1 is equal to or greater than about 2.

8. The optical display device of claim 7, wherein the H1/W1 is about 2 to about 6.

9. The optical display device of claim 1, wherein a pitch P1 of the plurality of wedge-shaped features is about 5 μιη to about 40 μιη.

10. The optical display device of claim 1, wherein an angle between a base of each wedge feature of the plurality of wedge features and an adjoining sidewall of each wedge feature is about 85 degrees to less than 90 degrees.

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

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

13. The optical display device of claim 1, wherein the plurality of wedge-shaped features have a refractive index nB and the microreplicated film base layer has a refractive index nF, Δn = nB-nF, and-0.3 < Δn <0.

14. A method of forming an environmental contrast filter, comprising:

rotating a first patterned roll in a first direction, the first patterned roll 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 including a second circumferential surface separated from the first circumferential surface by a first gap;

rotating a second support roller in the second direction, the second support roller including a third circumferential surface separated from the first circumferential surface by a second gap, the first patterned roller positioned between the first support roller and the second support roller;

directing a polymeric 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 patterned roll, the first patterned roll forming a plurality of recesses in the polymer matrix material; and

The support layer and the polymer matrix material are irradiated with a first UV light that cures the polymer matrix material to form a microreplicated film base layer that engages the support layer, the microreplicated film base layer and the support layer forming a microreplicated film.

15. The method of claim 14, further comprising directing the microreplicated film into a third gap between the third circumferential surface of the second backup roll and a fourth circumferential surface of an application roll rotating in the first direction, dispensing a light absorbing material into the third gap between the microreplicated film and the fourth circumferential surface of the application roll, 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 features in the microreplicated film base layer, the backup layer, the microreplicated film base layer, and the plurality of light absorbing wedge features forming an environmental contrast enhancement layer.

16. The method of claim 15, further comprising directing the environmental 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 patterned roller, dispensing a second polymeric material into the third gap between the environmental contrast enhancement layer and the fifth circumferential surface of the third support roller, and irradiating the second polymeric material with third UV light to at least partially cure the second polymeric material, the cured second polymeric material forming an IR layer that engages the environmental contrast enhancement layer.

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

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