A cover filter for a transparent display including leds

Abstract

There is provided a cover filter for a transparent display, the transparent display comprising a transparent backplane and one or more light sources positioned on the transparent backplane. The cover filter comprises an optical filter layer positioned on or over the one or more light sources, the optical filter layer comprising one or more transparent areas and one or more absorptive areas, the one or more absorptive areas absorbing light reflected from the one or more light sources, the one or more absorptive areas configured to be positioned to cover the one or more light sources; a first transparent layer positioned on the optical filter layer; and an anti-reflection layer optionally positioned on the first transparent layer.

Description

PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253A COVER FILTER FOR A TRANSPARENT DISPLAY INCLUDING LEDSCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63 / 698214 filed on September 24, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.BACKGROUND1. Field

[0002] The present disclosure relates to a cover filter for a transparent display, more specifically a cover filter structure including of light absorptive areas for reduction of ambient light reflection and transparent areas for light transmission for transparent microLED displays.2. Description of the Related Art

[0003] Transparent display technology allows images and data to be displayed on a transparent surface, such as glass providing users with a seamless blend of both the physical and digital world. Micro-LED displays typically include arrays of microscopic light emitting diodes (LEDs), each forming an individual pixel element. These displays can offer enhanced attributes such as flexibility, reduced power consumption, increased brightness, improve contrast, sharper images, and great reliability.

[0004] However, the transparent micro-LEDs also face optical challenges, particularly the reflection of external light on the transparent display. Various methods have been employed to reduce ambient light reflection in conventional displays. For example, tinted layer films control overall transmission to minimize reflection, while circular polarizers reduce reflection by polarization of ambient light. The patterned circular polarizer on glass (PCPoG) was once considered as a cutting-edge cover solution for micro-LED displays. While these methods are effective for conventional displays, they reduce the overall transparency of the displays. Currently, there is no cover solution that adequately accommodates the form factor of transparent Micro-LEDs.PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253SUMMARY

[0005] According to an aspect, there is provided a cover filter for a transparent display, the transparent display comprising a transparent backplane and one or more light sources positioned on the transparent backplane, comprising: an optical filter layer positioned on or over the one or more light sources, the optical filter layer comprising one or more transparent areas and one or more absorptive areas, the one or more absorptive areas absorbing light reflected from the one or more light sources, the one or more absorptive areas configured to be positioned to cover the one or more light sources; a first transparent layer positioned on the optical filter layer; and an anti-reflection layer optionally positioned on the first transparent layer.

[0006] In some embodiments, the cover filter may comprise a transparent adhesive layer configured to adhere the cover filter to the one or more light sources and the portions of the transparent backplane on which the one or more light sources are not placed, the transparent adhesive layer being positioned between the optical filter layer and the one or more light sources.

[0007] In some embodiments, the polarizing layer comprises liquid crystal with certain alignment for polarizing light, and the absorptive patterned areas in the polarizing layer comprise dyed liquid crystal.

[0008] In some embodiments, the optical filter layer may comprise a patterned circular polarizer, the patterned circular polarizer comprising a polarizing layer with the one or more transparent areas and the one or more absorptive patterns. The one or more absorptive patterned areas forms the one or more absorptive areas of the optical filter layer.

[0009] In some embodiments, the optical filter layer may comprise a tinted layer, the tinted layer comprises the one or more transparent areas and the one or more absorptive tinted areas. The one or more absorptive tinted areas forms the one or more absorptive areas of the optical filter layer.

[0010] In some embodiments, the transparent adhesive layer comprises optically clear adhesive (OCA) or optically clear resin (OCR).PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253

[0011] In some embodiments, the transparent adhesive layer may comprise OCR, and wherein the one or more transparent areas of the optical filter layer are openings, which are filled with OCR.

[0012] In some embodiments, the cover filter may comprise a transparent layer between the optical filter layer and the transparent adhesive layer.

[0013] In some embodiments, the patterned circular polarizer may further comprise a retarder layer positioned between the polarizing layer and the transparent adhesive layer.

[0014] In some embodiments, the optical filter layer may further comprise a primer layer positioned between the first transparent layer and the patterned circular polarizer and, the primer layer promoting adhesion between the first transparent layer and the patterned circular polarizer. The patterned circular polarizer may further comprise an intermediate layer for planarization positioned between the polarizing layer and the retarder layer.

[0015] In some embodiments, at least one of the transparent adhesive layer and the one or more transparent areas of the optical filter layer may comprise a plurality of scattering particles.

[0016] In some embodiments, the one or more light sources may comprise a plurality of light-emitting diodes (LEDs)

[0017] According to an aspect, there is provided a transparent display that includes a transparent backplane; one or more light sources positioned on the transparent backplane; and a cover filter of any one of some embodiments above, the cover filter being positioned on or over the one or more light sources.

[0018] According to an aspect, there is provided a method of manufacturing a transparent display. The method may comprise forming one or more light sources on a transparent backplane; forming an optical filter layer configured to be positioned on or over the one or more light sources so that the optical filter layer comprises one or more transparent areas and one or more absorptive areas for absorbing reflected light from the one or more light sources, the one or more absorptive areas configured to be positioned to cover the one or more light sources; forming a first transparent layer on the optical filter layer; and optionally forming an anti-reflection layer on the first transparent layer.

[0019] In some embodiments, the method may further comprise: forming a transparent adhesive layer between the optical filter layer and the one or more light sources so thatPCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 the transparent adhesive layer adheres the cover filter to the one or more light sources and the portions of the transparent backplane on which the one or more light sources are not placed.

[0020] In some embodiments, the method may further comprise: forming a second transparent layer between the optical layer and the transparent adhesive layer.

[0021] In some embodiments, the optical filter layer may comprise a patterned circular polarizer, the patterned circular polarizer comprising a polarizing layer with one or more transparent areas and one or more absorptive patterned areas, the one or more absorptive patterned areas forming the one or more absorptive areas of the optical filter layer.

[0022] In some embodiments, the optical filter layer may comprise a tinted layer, the tinted layer comprising one or more transparent areas and one or more absorptive tinted areas, the one or more absorptive tinted areas forming the one or more absorptive areas of the optical filter layer.

[0023] In some embodiments, the one or more light sources may comprise a plurality of light-emitting diodes (LEDs), and the transparent backplane may comprise a glass substrate.

[0024] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0026] FIG 1 shows a perspective view of a transparent display 100, comprising a plurality of tiles 104, according to some embodiments of the present disclosure;

[0027] FIG. 2 shows an enlarged view of one tile 104 from the plurality of tiles depicted FIG. 1 according to some embodiments of the present disclosure;

[0028] FIG. 3 shows a further enlarged view of area 'A' of the tile from FIG. 2, comprising a plurality of pixels 200 according to some embodiments of the present disclosure;PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253

[0029] FIG. 4 shows an enlarged view of a single pixel 200 from FIG. 3, displaying a plurality of chips 202 (e.g., LED chips);

[0030] FIG. 5a provides a cross-sectional view of a section of the transparent display 100, which is taken along the line 'B-B' of FIG. 4 according to some embodiments of the present disclosure;

[0031] FIG. 5b is a perspective view of the same section of the transparent display 100 shown in FIG. 5a;

[0032] FIG. 6 illustrates perspective views of exemplary absorptive areas with different shapes, according to some embodiments of the present disclosure;

[0033] FIG. 7 illustrates a cross-sectional view of a transparent featuring a cover filter that includes a patterned circular polarizer covering LEDs 702a, 702b, 702c, according to some embodiments of the present disclosure.

[0034] FIG. 8 illustrates a cross-sectional view of a transparent display with a cover filter that includes a patterned circular polarizer 803, 811 , 812, 813, 814, covering LEDs 802a, 802b, 802c, according to some embodiments of the present disclosure.

[0035] FIG. 9 shows a cross-sectional view of a transparent display with a cover filter that includes a patterned circular polarizer 903, 911 , 912, 913, 914, 915, covering LEDs 902a, 902b, 902c, according to some embodiments of the present disclosure.

[0036] FIG. 10 illustrates a cross-sectional view of a transparent display with a cover filter that includes a tinted layer 1003 as a polarizer layer.

[0037] FIG. 11 illustrates a cross-sectional view of a transparent display with a cover filter that includes a tinted layer 1103 as a polarizer layer.

[0038] FIG. 12 illustrates a cross-sectional view of a transparent display with a cover filter that includes scattering agents in a patterned circular polarizer, according to some embodiments of the present disclosure.

[0039] FIG. 13 illustrates a cross-sectional view of a transparent display with a cover filter that includes scattering agents in a patterned circular polarizer, according to other embodiments of the present disclosure.

[0040] FIG. 14 shows a graph illustrating the optical performance of estimated overall reflectance on micro-LED pixels of various cover solutions (a) to (g) for micro LED displays, as detailed in Table 1 .PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253

[0041] FIG.15 shows a graph illustrating the optical performance of estimated overall transmission, according to some embodiments of the present disclosure of various cover solutions (a) to (g) for micro LED displays, as detailed in Table 1.DETAILED DESCRIPTION

[0042] The disclosure will now be described more fully with reference to the accompanying drawings, in which some embodiments are shown. The subject matter of the disclosure may, however, be embodied in many different forms and should not be construed as being limited to some embodiments set forth herein. Rather, these embodiments are provided so that the disclosure will convey the subject matter to those skilled in the art. In the drawings, the thicknesses of layers and regions may be exaggerated for clarity. Wherever possible, like reference numerals in the drawings will denote like elements. Therefore, the disclosure is not limited by relative sizes or intervals as shown in the accompanied drawings.

[0043] 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 and / or to the other particular value. Similarly, when values are expressed as approximations, for example 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. 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.

[0044] 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.PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253This 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.

[0045] As used herein, the singular forms “a,” “an” and “the” include plural referents 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.

[0046] When a certain embodiment may be implemented differently, a specific process order may be performed differently from the described order. For example, two consecutively described processes may be performed substantially at the same time or performed in an order opposite to the described order.

[0047] As used herein, the term “transparent” refers to a material or layer having an optical transmittance of at least about 30 percent over a length of 500 millimeters in the visible region of the spectrum (about 420-750 nanometers).

[0048] As used herein, the term “non-transparent” refers to a material or layer having an optical transmittance of less than about 1 percent over a length of 500 millimeters in the visible region of the spectrum (about 420-750 nanometers).

[0049] As used herein, the term “anti-reflective” refers to a material, layer, or coating having a refractive index of greater than about 1 .0 and less than about 1 .4.

[0050] As used herein, the term “tinted” refers to a material, layer, or coating that has been treated with an additional material, layer, or coating such that the transmission of light through the material, layer, or coating is less than the transmission of light through the same material, layer, or coating that has not been treated with the additional material, layer, or coating.

[0051] As used herein, the term “a material with transformable transparency” refers to a material that undergoes a change in light transparency upon exposure to heat and / or light.

[0052] As used herein, the term “reflectance value” refers to the fraction or percentage of light emitted from light sources of a display area that is reflected back to the light sources.

[0053] FIG 1 shows a perspective view of a transparent display 100, comprising a plurality of tiles 104, according to some embodiments of the present disclosure. As shown in FIG.PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-2531 , plurality of tiles 104 are positioned in a MXN array on base plate 102. Tiles 104 can, for example, be components of a mirco-LED display while FIG. 1 shows a display area 100 comprising 20 tiles 104, embodiments disclosed herein include display areas comprising any number of tiles 104.

[0054] FIG. 2 shows an enlarged view of one tile 104 of the plurality of tiles of FIG. 1 according to some embodiments of the present disclosure. While not limited to any particular geometry, in certain exemplary embodiments, tile can have a rectangular shape.

[0055] FIG. 3 shows a further enlarged view of area 'A' of the tile from FIG. 2, comprising a plurality of pixels 200 according to some embodiments of the present disclosure. A lateral distance between immediately adjacent pixels 200 (shown as distance 'P' in FIG. 3) is defined as a pixel pitch P.

[0056] FIG. 4 illustrates an enlarged view of a single pixel 200 from FIG. 3, showing a plurality of chips 202 (e.g., LED chips). The chips 202 may, for example, comprise red- green-blue (RGB) chips (e.g., a RGB LED chip). As shown in FIG. 4, the display area 100 can extend around a chip 202. While FIG. 4 shows display area 100 extending around one chip 202, embodiments disclosed herein include those in which display area 100 extends around a plurality of chips 202.

[0057] FIG. 5a provides a cross-sectional view of a section of the transparent display 100, which is taken along the line 'B-B' of FIG. 4 according to some embodiments of the present disclosure. The transparent display may comprise a transparent backplane 201 , one or more light sources 202 positioned on the transparent backplane 201 , and a cover filter 203, 204, 205, 206 positioned on or over the one or more light sources 202. The transparent backplane 201 may be a transparent substrate, such as a glass substrate or light emitters. However, the transparent substrate is not limited to a glass substrate or light emitters if it is optically transparent. The one or more light sources 202 may be lightemitting diodes (LEDs) or micro-LEDs, but are not limited to these options.

[0058] The cover filter may comprise an optical filter layer 203 that includes one or more transparent areas 203a and one or more absorptive areas 203b. Transmission rate of the absorptive areas 203b may be, for example, from about 30 % to about 90%. Thickness of the optical filter layer 203 may be, for example, from about 1 m to about 20 pm. External light passes through the optical filter layer 203 and is reflected on any reflective objectsPCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 within the transparent display, such as the one or more light sources 202a, 202b, 202c, electrodes, and lines. The reflected light then passes back through the optical filter layer 203 and exits the transparent display. The one or more absorptive areas 203b absorb light reflected from the one or more light sources 202. The one or more absorptive areas 203b may be configured to be positioned to cover the one or more light sources 202. The one or more transparent areas 203a may be optically transparent portions or openings in the optical filter layer 203. The optical filter layer 203 extends over the plurality of chips 202.

[0059] In some embodiments, the optical filter layer 203 may comprise a patterned circular polarizer for reflection reduction. The patterned circular polarizer comprises one or more transparent areas 203a and one or more absorptive patterned areas 203b. The patterned circular polarizer can significantly reduce reflections from the one or more light sources 202 by polarizing the light.

[0060] Alternatively, in some embodiments, the optical filter layer 203 may comprise a tinted layer for controlling transmission. The tinted layer may comprise one or more transparent areas 203a and one or more absorptive tinted areas 203b. The tined layer has advantages in controlling transparency of 50% to 90%.

[0061] The cover filter may further comprise a first transparent layer 204 positioned on the optical filter layer 203; and an anti-reflective layer 205 positioned on the first transparent layer 204. The first transparent layer 204 may comprise, for example, at least one material selected from glass materials, polymeric materials, ceramic materials, and sapphire, which may or may not be tinted and / or have transformable transparency. Transmission rate of the first transparent layer 204 may be, for example, from about 60% to about 95%. Thickness of the first transparent layer 204 may be, for example, from about 20 m to about 2 mm.

[0062] The anti-reflective layer 205 may comprise anti-reflective material that comprises, for example, at least one selected from magnesium fluoride, fluoropolymers, mesoporous silica nanoparticles, thin interference films, and layers with engineered surfaces, such as nanopatterned glasses. For example, AR film or coating may be applied on first transparent layer to reduce surface reflection as anti-reflective layer 205. TransmissionPCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 rate of the anti-reflective layer 205 may be, for example, more than 90%. Thickness of the anti -reflective layer 205 may be, for example, not more than 100 m.

[0063] The cover filter may further comprise a transparent adhesive layer 206 for adhering the cover filter to the one or more light sources 202 and the portions of the transparent backplane 201 on which the one or more light sources 202 are not placed. The transparent adhesive layer 206 can be integrated with LED displays through lamination. It may be positioned between the optical filter layer 203 and the one or more light sources 202. The transparent adhesive layer 206 may comprise optically clear adhesive (OCA) or optically clear resin (OCR). If the transparent adhesive layer 206 comprises OCR, the one or more transparent areas 203a of the optical filter layer 203 may be also filled with OCR.

[0064] According to some embodiments of the present disclosure, a method of manufacturing a transparent display in FIG. 5a may comprise forming one or more light sources on a transparent backplane; forming an optical filter layer configured to be positioned on or over the one or more light sources so that the optical filter layer comprises one or more transparent areas and one or more absorptive areas for absorbing reflected light from the one or more light sources, the one or more absorptive areas configured to be positioned to cover the one or more light sources; forming a first transparent layer on the optical filter layer; and forming an anti-reflection layer on the first transparent layer. The method may further comprise: forming a transparent adhesive layer between the optical filter layer and the one or more light sources so that the transparent adhesive layer adheres the cover filter to the one or more light sources and the portions of the transparent backplane on which the one or more light sources are not placed. The method may further comprise: forming a second transparent layer between the optical layer and the transparent adhesive layer.

[0065] The optical filter layer may comprise a patterned circular polarizer, the patterned circular polarizer comprising a polarizing layer with one or more transparent areas and one or more absorptive patterned areas, the one or more absorptive patterned areas forming the one or more absorptive areas of the optical filter layer. The optical filter layer may comprise a tinted layer, the tinted layer comprising one or more transparent areas and one or more absorptive tinted areas, the one or more absorptive tinted areas forming the one or more absorptive areas of the optical filter layer. The one or more light sourcesPCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 may comprise a plurality of light-emitting diodes (LEDs), and the transparent backplane may comprise a glass substrate.

[0066] FIG. 5b is a perspective view of the same section of the transparent display 100 shown in FIG. 5a. In FIG. 5b, the absorptive areas 203b cover the one or more light sources 202a, 202b, 202c so that the absorptive areas 203b can absorb light reflected from the one or more light sources 202a, 202b, 202c. The cover filter structure shown in FIG. 5a is distinct from uniform optical films, such as conventional tinted film or circular polarizer films, due to its inclusion of open areas. While previous open window approaches, like the Black matrix (BM) or Patterned Circular Polarizer on Glass (PCPoG), feature open areas covering light sources, the cover filter structure in some embodiments, as illustrated in FIGs. 5a and 5b, positions the absorptive areas 203b to cover the one or more light sources 202a, 202b, 202c. Cover filters in the prior art are suitable for conventional micro-LEDs that favor black or neutral tones with high luminous efficiency. In contrast, the cover filter structure according to some embodiments of the present disclosure ensures high optical transmittance and manageable reflectance by selectively positioning the absorptive areas 203b over the light sources 202a, 202b, 202c within pixels.

[0067] FIG. 6 illustrates perspective views of exemplary absorptive areas with different shapes, according to some embodiments of the present disclosure: (a) absorptive areas 203b separately covering individual R, G, B light sources 202a, 202b, 202c; (b) an absorptive area 203b’ collectively covering a set of R, G, B light sources 202a, 202b, 202c; and (c) an absorptive area 203b” covering individual R, G, B light sources 202a, 202b, 202c, as well as electrodes (not shown) and lines 220, 230. However, the shape of the absorptive area is not limited to (a) to (c) of FIG. 6.

[0068] Referring to FIG. 6, the absorptive areas can be determined by selecting reflective parts, pattern shape and size. In Example (a) of FIG. 6, the absorptive areas 203b cover only the one or more light sources 202a, 202b, 202c, increasing the transparent area 203a of the optical filter area, which results in higher display transparency while minimizing low reflection of ambient light. In Example (a) of FIG. 6, the absorptive areas 203b may be slightly smaller or larger than each light source 202a, 202b, 202c (forPCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 example R, G, B LEDs), accounting for pattern capabilities and providing a buffer for misalignment.

[0069] In Example (b) of FIG. 6, a single absorptive area 203b’ covering a set of R, G, B light sources 202a, 202b, 202c offers advantages in pattern resolution as it simplifies the patterning process by making it easier to pattern the single absorptive area 203b’ during display fabrication. However, this cover solution reduces the transparent areas 203a of the optical filter layer 203. This reduction leads to a decrease in the transmission of the transparent display 100.

[0070] In Example (c) of FIG. 6, the absorptive area 203b” covers not only the R, G, B light sources 202a, 202b, 202c but also the electrodes (not shown) and lines 220, 230. This cover solution may fully block light reflected from electrodes and lines as well as light sources. However, this cover solution leads the transparent areas 203a in the optical filter layer to be minimized, overall transparency of the display will decrease despite reduction of ambient light reflection. Consequently, the transmission of the transparent display will drop.

[0071] Different types of optical filter on micro LEDs result in varying estimated reflectance levels in the LED area covered by absorptive areas 203b and affect the percentage of open area formed by transparent areas, as illustrated in example of Table 1 below.

[0072]

[0073] Estimated reflectance of LED and open area of various types of optical filter with micro LED

[0075] Example (a) of Table 1 shows that a transparent micro-LED with R, G, B LEDs, without absorptive areas, has a 60 % reflectance of in the LED area and a 93% open area. The reflectance in the LED parts indicates ambient light reflection. Even if LEDs cover a small area, ambient light reflection on the LED parts can hinder the viewer’s perception of the display. In Example (b) of Table 1 , a transparent micro-LED using TintedPCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 film (transmission rate: 50) has a 16% of reflectance in the LED area, while transmission rate of the open area is 0%. Example (c) of Table 1 shows that a transparent micro-LED using a circular polarizer on the micro-LEDs has a 2% reflectance in the LED area, with a 0% transmission rate in the open area, as the Circular Polarizer significantly reduces reflection by polarizing ambient light.

[0076] In Example (d) of Table 1 , a transparent micro-LED using Black Matrix with an open window to the LEDs has a 51 % reflectance in the LED area and a 0% transmission rate in the open area. Example (e) of Table 1 shows that a transparent micro-LED using Patterned Circular Polarizer with an open window to the LEDs also has a 51 % reflectance in the LED area and a 0% transmission rate in the open area. Examples (a) to (c) use uniform film layers, such as tined film or circular polarizer, providing uniform optical characteristics. While Examples (b) to (c) significantly reduce reflection in the LED parts, there is no open area in these methods. On the other hand, Examples (d) and (e) feature an open window for the LEDs while covering the other area with Black matrix or Circular Polarizer. Examples (d) and (e) nearly decrease reflection in the LED area, and they don’t have open area either.

[0077] In Example (f) of Table 1 , a transparent micro-LED using a Patterned Circular Polarizer with absorptive areas covering the LEDs, according to some embodiments of the present disclosure, has a 2% reflectance in the LED area and an 84% transmission rate in the open area. Example (g) of Table 1 shows that a transparent micro-LED using a Patterned Circular Polarizer with absorptive areas covering the LEDs according to some embodiments of the present disclosure has 16% of reflectance of LED area and the transmission rate of open area is 84%. Therefore, compared to conventional cover solutions (a) to (e), (f) and (g) showing the embodiments of the present disclosure can decrease LED reflection (2%, 16% respectively), and they have large open area (84%) comparable to open area of (a) micro LED (93%). Accordingly, Examples (f) and (g) lead to remarkably improved transparency of the transparent display 100.

[0078] FIG. 7 illustrates a cross-sectional view of a transparent featuring a cover filter that includes a patterned circular polarizer covering LEDs 702a, 702b, 702c, according to some embodiments of the present disclosure. The cover filter is positioned on or over the one or more light sources 702a, 702b, 702c which are placed on a transparent backplanePCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253701 . The cover filter comprises a transparent adhesive layer 706 between the transparent backplane 701 and the patterned circular polarizer layer.

[0079] The cover filter comprises the patterned circular polarizer 703, 711 , 712, 713, and 714, a first transparent layer 704 positioned on the patterned circular polarizer, and an anti-reflective layer 705 positioned on the first transparent layer 704. The cover filter may further comprise a transparent adhesive layer 706 under the patterned circular polarizer. The patterned circular polarizer may further comprise a polarizing layer 703 including transparent areas 703a and absorptive patterned areas 703b covering light sources 702a, 702b, 702c, according to some embodiments of the present disclosure. The patterned circular polarizer consists of polarizer (light absorptive part) which can be patterned by various printing methods (for example, photolithography, Inkjet printing, screen printing, etching process, etc.). The polarizing layer 703 may comprise dyed liquid crystal with certain alignment for polarizing light. The absorptive patterned areas 703b in the polarizing layer 703 are formed as dyed liquid crystal part, using for example, polymer, but not limited to this option.

[0080] The patterned circular polarizer may further comprise a primer layer 714 positioned on the polarizing layer 703. The primer layer 714 promote adhesion between the polarizing layer 703 and the first transparent layer 704. The patterned circular polarizer may further comprise a retarder layer 711 , a second primer layer 712, and an intermediate layer 713. The retarder layer 711 is positioned between the transparent adhesive layer 706 and the primer layer 712, and comprises liquid crystal with certain alignment for retardation of light reflected from the one or more light sources 702a, 702b, 702c. In FIG. 7, external light entering the transparent display is polarized as it passes through the polarizing layer 703. Then, it becomes circularly polarized upon passing through the retarder layer 711 , making it difficult for the circularly polarized light to pass back through the polarizing layer 703. This process effectively minimizes the reflection of external light.

[0081] The second primer layer 712 is positioned on the retarder layer 711 , and promotes adhesion between the intermediate layer 713 and the retarder layer 711. The intermediate layer 713 is positioned between the second primer layer 712 and the polarizing layer 703. The intermediate layer 713 planarizes the second primer layer 712, providing a smooth surface for applying the liquid crystal to form the polarizing layer 703. The materialsPCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 forming the circular polarizer, including the polarizing layer, consist of liquid crystals arranged in a specific direction. As a result, the surface is non-uniform, and the cured state of the liquid crystals is relatively weak, necessitating planarization as separate layers.

[0082] TFIG. 8 illustrates a cross-sectional view of a transparent display with a cover filter that includes a patterned circular polarizer 803, 811 , 812, 813, 814, covering LEDs 802a, 802b, 802c, according to some embodiments of the present disclosure. The stacking configuration of the pattern circular polarizer in FIG. 8 is similar to that of the pattern circular polarizer in FIG. 7, except that openings are formed through overall thickness of the pattern circular polarizer 803, 811 , 812, 813, 814 in the portions corresponding to the transparent areas 703a of FIG. 7. In FIG. 8, a transparent adhesive layer 806 is formed between a retarder layer 811 in the patterned circular polarizer and the transparent backplane 801 on which LEDs 802a, 802b, 802c are positioned. The transparent adhesive layer 806 may comprise OCR, with which the openings in the patterned circular polarizer are also filled. In this case, when the patterned circular polarizer is integrated into the LEDs 802a, 802b, and 802c on the transparent backplane 801 , several processes - such as separate formation of transparent areas 803a, coating the patterned circular polarizer, and bonding between the polarizer and the LEDs - can be eliminated.

[0083] FIG. 9 shows a cross-sectional view of a transparent display with a cover filter that includes a patterned circular polarizer 903, 911 , 912, 913, 914, 915, covering LEDs 902a, 902b, 902c, according to some embodiments of the present disclosure. The stacking configuration of the pattern circular polarizer in FIG. 9 is similar to that of the pattern circular polarizer in FIG. 7, except that a second transparent layer 911 is formed as a bottom layer of the patterned circular polarizer on the transparent adhesive layer 906. The materials forming the circular polarizer, including the polarizing layer 903, consist of liquid crystals arranged in a specific direction. Consequently, the surface is non-uniform, and the cured state of the liquid crystals is relatively weak, which may necessitate the second transparent layer 911 as a protective film as well as an intermediate layer 914 for planarization, as separate layers. The transparent layer addresses material deformation in two ways: by improving flatness and providing protection / buffering from external substances. In FIG. 9, the transparent areas 903a in the polarizing layer 903 may bePCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 formed as openings. A transparent adhesive layer 906 in FIG. 9 may comprise OCA, placed between the patterned circular polarizer and the transparent backplane 901 , on which LEDs 902a, 902b, 902c are positioned.

[0084] FIG. 10 illustrates a cross-sectional view of a transparent display with a cover filter that includes a tinted layer 1003 as an optical filter layer. The cover filter is positioned on or over the one or more light sources 1002a, 1002b, 1002c which are positioned on a transparent backplane 1001. The cover filter comprises a transparent adhesive layer 1006 between the tinted layer 1003 and the transparent backplane 1001 on which the one or more light sources 1002a, 1002b, 1002c are placed. The transparent adhesive layer 1006 may comprise, for example, OCR or OCA, but is not limited to them. The cover filter comprises the tinted layer 1003, a first transparent layer 1004 positioned on the tinted layer 1003, and anti-reflective layer 1005 positioned on the first transparent layer 1004.

[0085] The tinted layer 1003 comprises transparent areas 1003a and absorptive tinted areas 1003b, according to some embodiments of the present disclosure. The absorptive areas 1003b cover the light sources 1002a, 1002b, 1002c so that the light reflected from the light sources 1002a, 1002b, 1002c can be absorbed upon passing through the absorptive areas. Unlike the patterned circular polarizer in FIGs. 7 through 9, the tined layer 1003 is assumed to be formed as a single layer and merely absorb external light and / or reflected light. For example, if a tinted layer 1003 absorbs 50% of light, then 50% of the external light will pass through the absorptive areas 1003b of the tinted layer 1003. When this light is reflected, 50% of the reflected light will be absorbed by the absorptive areas 1003b. As a result, 25% of the external light will pass through the absorptive areas 1003b.

[0086] FIG. 11 illustrates a cross-sectional view of a transparent display with a cover filter that includes a tinted layer 1103 as an absorptive layer. The tinted layer in FIG. 11 is similar to that of the tinted layer in FIG. 10, except that a second transparent layer 1107 is positioned between the tinted layer 1103 and the transparent adhesive layer 1106. The second transparent layer 1107 further protects the tinted layer 1103, and thus improves reliability of the transparent display. In FIG. 11 , a transparent adhesive layer 1106 may comprise, for example, OCR or OCA, but not limited to them.PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253

[0087] FIG. 12 illustrates a cross-sectional view of a transparent display with a cover filter that includes scattering agents in a patterned circular polarizer, according to some embodiments of the present disclosure. The stacking configuration of the pattern circular polarizer 1203, 1211 , 1212, 1213, 1214 in FIG. 12 is similar to that of the pattern circular polarizer in FIG. 7, except that at least one transparent portion of the patterned circular polarizer, such as transparent areas 1203a, an intermediate layer 1213, and / or a transparent adhesive layer 1206, may include scattering agents 1215. However, other portions of the cover filter may include the scattering agents, depending on the specific needs of scattering functions.

[0088] The scattering agents may be for example scattering particles such as silica, glass, and / or polymer beads (e.g., polystyrene, epoxy). The particles may have a size (e.g., diameter) in a range from about 10 nanometers to about 2 micrometers. The scattering agent may include gexafluro-iso-prophy metacrylate, 2,2,2 trifluroethyl metacrylate, N- benzylmetahcrylamide, and / or benzyl methacrylate. The scattering agent may be present in an amount from about 0 wt.% to about 10 wt.% in the transparent portions.

[0089] FIG. 13 illustrates a cross-sectional view of a transparent display with a cover filter that includes scattering agents in a patterned circular polarizer, according to other embodiments of the present disclosure. The stacking configuration of the pattern circular polarizer 1303, 1311 , 1312, 1313, 1314, 1315 in FIG. 13 is similar to that of the pattern circular polarizer in FIG. 9, except that at least one transparent portion of the patterned circular polarizer, such as transparent areas 1303a, an intermediate layer 1313, and / or a second transparent layer 1311 , may comprise scattering agents 1316.

[0090] FIGs. 14 and 15 depict the optical performances of various cover solutions (a) to (g) for micro LED displays, as detailed in Table 1. FIG. 14 shows a graph illustrating the optical performance of estimated overall reflectance on micro-LED pixels of various cover solutions (a) to (g) for micro LED displays, as detailed in Table 1. FIG.15 shows a graph illustrating the optical performance of estimated overall transmission of various cover solutions (a) to (g) for micro LED displays, as detailed in Table 1.

[0091] Referring to Table 1 and FIG. 14, even if reflectance of LED is 60% in Table 1 , the overall reflectance of micro LED is 9% due to the small LED areas, as shown by a first bar from the left end in FIG. 14. All previous cover filters (bars other than the two barsPCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 from the right end in FIG. 14 according to some embodiments of the present disclosure), regardless of the concepts, have non-transparent cover solution (less than 50% of overall transmission). However, the transparent displays with a patterned circular polarizer or a tinted layer (as shown by the two bars from the right end in FIG. 14) exhibit high overall transmission with low reflection. This is because the methods involving small absorptive areas on LED and large open area (transparent areas) proportional to overall transmission. A patterned Circular Polarizer on Glass (PCPoG) mentioned in Background focuses on the luminous efficiency of micro-LED displays. However, the layer characteristics of such cover solutions do not meet the high transparency requirements of transparent micro-LED displays. In contrast, the PCPoG with absorptive patterned areas, according to some embodiment of the present disclosure, is configured to have an inverse layer structure, as compared to the conventional PCPoG, thereby reducing reflection and increasing transparency for transparent micro displays.

[0092] While the disclosure has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.

Claims

PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253WHAT IS CLAIMED IS:

1. A cover filter for a transparent display, the transparent display comprising a transparent backplane and one or more light sources positioned on the transparent backplane, comprising: an optical filter layer positioned on or over the one or more light sources, the optical filter layer comprising one or more transparent areas and one or more absorptive areas, the one or more absorptive areas absorbing light reflected from the one or more light sources, the one or more absorptive areas configured to be positioned to cover the one or more light sources; and a first transparent layer positioned on the optical filter layer;.

2. The cover filter of claim 1 , further comprising a transparent adhesive layer configured to adhere the cover filter to the one or more light sources and the portions of the transparent backplane on which the one or more light sources are not placed, the transparent adhesive layer being positioned between the optical filter layer and the one or more light sources.

3. The cover filter of claim 1 , wherein the optical filter layer comprises a patterned circular polarizer, the patterned circular polarizer comprising a polarizing layer with the one or more transparent areas and the one or more absorptive patterned areas, and wherein the one or more absorptive patterned areas forms the one or more absorptive areas of the optical filter layer.

4. The cover filter of claim 3, wherein the polarizing layer comprises liquid crystal with certain alignment for polarizing light, and wherein the absorptive patterned areas in the polarizing layer comprise dyed liquid crystal.

5. The cover filter of claim 1 , wherein the optical filter layer comprises a tinted layer, and wherein the tinted layer comprises one or more transparent areas and onePCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 or more absorptive tinted areas, and wherein the one or more absorptive tinted areas forms the one or more absorptive areas of the optical filter layer.

6. The cover filter of claim 2, wherein the transparent adhesive layer comprises optically clear adhesive (OCA) or optically clear resin (OCR).

7. The cover filter of claim 6, wherein the transparent adhesive layer comprises OCR, and wherein the one or more transparent areas of the optical filter layer are openings, which are filled with OCR.

8. The cover filter of claim 2, further comprising a transparent layer between the optical filter layer and the transparent adhesive layer.

9. The cover filter of claim 3, wherein the patterned circular polarizer further comprises a retarder layer positioned between the polarizing layer and the transparent adhesive layer.

10. The cover filter of claim 9, wherein the optical filter layer further comprises a primer layer positioned between the first transparent layer and the patterned circular polarizer and, the primer layer promoting adhesion between the first transparent layer and the patterned circular polarizer, and wherein the patterned circular polarizer further comprises an intermediate layer for planarization positioned between the polarizing layer and the retarder layer.11 .The cover filter of claim 2, wherein at least one of the transparent adhesive layer and the one or more transparent areas of the optical filter layer comprise a plurality of scattering particles.

12. The cover filter of any one of claims 1 to 11 , wherein the one or more light sources comprise a plurality of light-emitting diodes (LEDs).

13. The cover filter of any one of claims 1 to 12, further comprising an anti-reflection layer positioned on the first transparent layer.PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-25314. The cover filter of any one of claims 1 to 13, further comprising one or more electrodes or lines positioned on the transparent backplane, wherein the one or more absorptive areas are configured to be positioned to cover the one or more electrodes or lines.

15. A transparent display comprising: a transparent backplane; one or more light sources positioned on the transparent backplane; and a cover filter of any one of claims 1 to 11 , the cover filter being positioned on or over the one or more light sources.

16. The transparent display of claim 15, wherein the one or more light sources comprise a plurality of light-emitting diodes (LEDs), and wherein the transparent backplane comprises a glass substrate.

17. A method of manufacturing a transparent display, comprising: forming one or more light sources on a transparent backplane; forming an optical filter layer configured to be positioned on or over the one or more light sources so that the optical filter layer comprises one or more transparent areas and one or more absorptive areas for absorbing reflected light from the one or more light sources, the one or more absorptive areas configured to be positioned to cover the one or more light sources; and forming a first transparent layer on the optical filter layer.

18. The method of claim 17, further comprising: forming a transparent adhesive layer between the optical filter layer and the one or more light sources so that the transparent adhesive layer adheres the cover filter to the one or more light sources and the portions of the transparent backplane on which the one or more light sources are not placed.

19. The method of claim 17, further comprising:PCT / US25 / 46522 16 September 2025 (16.09.2025)SP24-253 forming a second transparent layer between the optical layer and the transparent adhesive layer.

20. The method of claim 17, wherein the optical filter layer comprises a patterned circular polarizer, the patterned circular polarizer comprising a polarizing layer with one or more transparent areas and one or more absorptive patterned areas, the one or more absorptive patterned areas forming the one or more absorptive areas of the optical filter layer.

21. The method of claim 17, wherein the optical filter layer comprises a tinted layer, the tinted layer comprising one or more transparent areas and one or more absorptive tinted areas, the one or more absorptive tinted areas forming the one or more absorptive areas of the optical filter layer.

22. The method of any one of claims 17 to 21 , wherein the one or more light sources comprise a plurality of light-emitting diodes (LEDs), and wherein the transparent backplane comprises a glass substrate.

23. The method of any one of claims 17 to 22, further comprising forming an antireflection layer on the first transparent layer.

24. The method of any one of claims 17 to 23, further comprising forming one or more electrodes or lines on the transparent backplane, wherein the one or more absorptive areas are configured to be positioned to cover the one or more electrodes or lines.

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