Backlight leakage reduction for transparent displays

Abstract

A transparent display with reduced backlight leakage and methods for its fabrication are provided herein. The display incorporates substrate layers, light-absorbing elements, and optical interfaces to control light propagation. The transparent display considers the relationship between component thicknesses and light-emitting element spacing to manage reflected light paths across various viewing angles. The transparent display may include specialized coatings, structured optical elements, and / or wire mesh configurations to further reduce backlight leakage. These elements collectively minimize unwanted backlight transmission while maintaining display quality and transparency by positioning and aligning these components to achieve backlight leakage reduction. These advancements enhance the performance, privacy, and visual quality of transparent displays across various applications.

Description

SP24-281BACKLIGHT LEAKAGE REDUCTION FOR TRANSPARENT DISPLAYSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 63 / 716848 filed on November 6, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.FIELD

[0002] Embodiments of the present disclosure relate to displays, and, more particularly, to transparent displays and methods for reducing backlight leakage in such displays.BACKGROUND

[0003] Transparent displays, including transparent micro-light emitting diode (microLED) and organic light emitting diode (OLED) displays, are emerging as promising technologies for various applications such as augmented reality, vehicle displays, transparent windows, transparent doors, public information displays, and advertising. These displays offer advantages like larger size enabling, high brightness, high transparency, low power consumption and the ability to overlay digital content on real-world scenes.

[0004] One of the issues with current transparent displays is backlight leakage. Backlight leakage occurs when light from the display’s emitters become visible from unintended angles, particularly from the back of the display. This phenomenon can result from various factors including internal reflections, scattering of light within the display structure, and imperfect light management systems. This may create problems such as privacy concerns for applications where the display content is intended to be visible only from the front side, and degradation of see-through clarity from the back side of the display.

[0005] Conventional approaches to suppress this effect typically involve adding an antireflection (AR) coating to the front surface of the display. However, it's challenging to achieve high-performance AR coating over all visible wavelengths at all incident angles. Moreover, the reflection of AR coating is normally optimized for incident angles around a normal viewing direction of the front surface. As a result, the issue of backlight leakage persists or even worsens at large back view angles.

[0006] Attempts to address this problem by reducing the overall thickness of the cover can lead to a reduction in the mechanical rigidity and strength of the display. It may also increase the difficulty and cost of the encapsulation process. Similarly, increasing the distance between pixels of the display may result in reduced display resolution.SP24-281

[0007] Therefore, there is a need for improved designs and methods to suppress backlight leakage in transparent displays, particularly at large viewing angles, without compromising the display's resolution, mechanical properties, or manufacturing feasibility.BRIEF SUMMARY

[0008] Various embodiments contemplated herein provide transparent displays with reduced backlight leakage and methods for their fabrication. These embodiments address the challenges associated with managing light paths within transparent displays to minimize unwanted light transmission while maintaining display quality and transparency.

[0009] In various aspects, the disclosed embodiments incorporate structures and configurations to control the propagation of light within the transparent display. These structures may include specially configured substrate layers, light-absorbing elements, and optimized optical interfaces. The arrangements of these components are positioned to redirect, absorb, and / or block light that would otherwise contribute to backlight leakage. Some embodiments focus on the relationship between the thickness of display components and the spacing of light-emitting elements. By controlling these parameters, the transparent display may effectively manage light paths across a wide range of viewing angles. This approach allows for the reduction of backlight leakage without compromising the transparent display's resolution or overall transparency.

[0010] Additional features in various embodiments may include specialized coatings, structured optical elements, or alternative light-absorbing configurations. These elements work in concert to provide comprehensive control over light propagation within the transparent display, addressing backlight leakage through multiple mechanisms.

[0011] Methods of designing and producing the transparent displays are also contemplated. A designer may tailor the design of the transparent display based on the design requirements for various properties such as resolution required, maximum view angle required, etc.

[0012] In an example embodiment, a transparent display defining a front and a back is provided. The transparent display comprises a first glass substrate comprising a first side and a second side and a second glass substrate comprising a first side and a second side. The transparent display comprises a first layer between the second side of the first glass substrate and the first side of the second glass substrate. The first layer comprises a plurality of pixel emitting structures, each of the plurality of pixel emitting structures comprising one or moreSP24-281 light-emitting components. The transparent display comprises a second layer positioned on the second side of the second glass substrate. The second layer comprises a plurality of lightabsorbing elements, each of the plurality of light-absorbing elements being aligned from the front to the back of the transparent display with a corresponding pixel emitting structure in the first layer, the light-absorbing elements being configured to absorb light reflected from the first glass substrate to reduce an amount of light visible from the back of the transparent display.

[0013] In some embodiments, the first glass substrate comprises an anti-reflective coating on the first side of the first glass substrate.

[0014] In some embodiments, the transparent display comprises a third glass substrate. The third glass substrate comprising a first side and a second side. The third glass substrate is positioned adjacent the second layer on the second side of the second glass substrate. The transparent display comprises a third layer comprising a plurality of light-absorbing elements. The third layer is positioned on the second side of the third glass substrate.

[0015] In some embodiments, the third glass substrate is configured as a back cover.

[0016] In some embodiments, each pixel emitting structure of the plurality of pixel emitting structures comprises a non-transmissive region. The non-transmissive region includes the one or more light-emitting components and an area surrounding the one or more light-emitting components. Furthermore, in some embodiments, a surface area of each of the plurality of light-absorbing elements is substantially equal to a surface area of the non- transmissive region of the corresponding pixel emitting structure. The surface area being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display. Additionally, in some embodiments, a surface area of each of the plurality of lightabsorbing elements is less than a surface area of the non-transmissive region of the corresponding pixel emitting structure. The surface area being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display. In some embodiments, a surface area of each of the plurality of light-absorbing elements is greater than a surface area of the non-transmissive region of the corresponding pixel emitting structure. The surface area being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display.

[0017] In some embodiments, the one or more light-emitting components comprise micro-LEDs. Furthermore, in some embodiments, the one or more light-emitting components comprise OLEDs.SP24-281

[0018] In some embodiments, a thickness of the first glass substrate is selected relative to a horizontal spacing of the plurality of pixel emitting structures relative to each other. The horizontal spacing being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display. The thickness is configured to cause light emitted from a first pixel emitting structure at a first range of reflection angles off the first glass substrate to be reduced by a non-transmissive region of one or more pixel emitting structures of the plurality of pixel emitting structures. Furthermore, in some embodiments, the first range of reflection angles includes angles extending from 55 degrees to 90 degrees relative to a viewing direction of the transparent display.

[0019] In some embodiments, a thickness of the second glass substrate is selected to position the plurality of light-absorbing elements to absorb light at a second range of angles. The second range of angles being from approximately 1 degree to 90 degrees relative a viewing direction of the transparent display. The positioning of the plurality of lightabsorbing elements is determined relative to the horizontal spacing of the plurality of pixel emitting structures relative to each other.

[0020] In some embodiments, the first glass substrate comprises an anti-reflective coating on the first side of the first glass substrate. The anti -reflective coating on the first side of the first glass substrate configured to reduce reflection of light at a third range of reflection angles. The third range of reflection angles is from 0 degrees to approximately 70 degrees relative to the viewing direction of the transparent display.

[0021] In some embodiments, the second layer has a thickness ranging from 0.5 micrometers to 0.5 millimeters.

[0022] In some embodiments, the light-absorbing elements comprise a wire mesh structure. The wire mesh structure comprises a plurality of interconnected wires arranged in a grid pattern. The intersections of the grid pattern align from the front to the back of the transparent display with the corresponding pixel emitting structure.

[0023] In another example embodiment, a transparent display defining a front and a back is provided. The transparent display comprises a first glass substrate comprising a first side and a second side and a second glass substrate comprising a first side and a second side. The transparent display comprises a first layer between the second side of the first glass substrate and the first side of the second glass substrate. The first layer comprises a plurality of pixel emitting structures, each pixel emitting structure of the plurality of pixel emitting structures comprising one or more light-emitting components and a non-transmissive region. The non-SP24-281 transmissive region includes the one or more light-emitting components and an area surrounding the one or more light-emitting components. The plurality of pixel emitting structures are arranged with a horizontal spacing between adjacent pixel emitting structures, the horizontal spacing being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display. Furthermore, a thickness of the first glass substrate and the horizontal spacing between adjacent pixel emitting structures are each configured such that a portion of light emitted from the one or more light-emitting components of a first pixel emitting structure that reflects off the first glass substrate is blocked by the non-transmissive region of an adjacent second pixel emitting structure. This reduces an amount of light leakage viewable from the back of the transparent display.

[0024] In some embodiments, the reduction in the amount of light leakage viewable from the back of the transparent display occurs at a function of a view angle,. The function of view angle is determined by: 0; = sin-1wherein tf is the thickness of the first glass substrate, p is the horizontal spacing between adjacent pixel emitting structures, no is a refractive index the surrounding medium, and ni is the refractive index of the first glass substrate.

[0025] In some embodiments, the thickness of the first glass substrate and the horizontal spacing between adjacent pixel emitting structures are related by a ratio tf / p. Furthermore, in some embodiments, the ratio tf / p of the thickness of the first glass substrate to the horizontal spacing between adjacent pixel emitting structures is between 1.425 and 7.0.

[0026] In some embodiments, the one or more light-emitting components comprise micro-LEDs.

[0027] In some embodiments, the transparent display comprises an anti-reflective coating on the first side of the first glass substrate. The anti-reflective coating configured to reduce reflection of light at angles from 0 degrees to approximately 70 degrees relative to a viewing direction of the transparent display. Furthermore, the plurality of pixel emitting structures are configured to reduce light at angles from approximately 55 degrees to 90 degrees relative to the viewing direction of the transparent display.

[0028] In another example embodiment, a transparent display defining a front and a back is provided. The transparent display comprises a first glass substrate comprising a first side and a second side and a second glass substrate comprising a first side and a second side. The transparent display comprises a first layer between the second side of the first glass substrate and the first side of the second glass substrate. The first layer comprises a plurality of pixelSP24-281 emitting structures, each pixel emitting structure of the plurality of pixel emitting structures comprising one or more light-emitting components and a non-transmissive region. The non- transmissive region includes the one or more light-emitting components and an area surrounding the one or more light-emitting components. The plurality of pixel emitting structures are arranged with a horizontal spacing between adjacent pixel emitting structures. The horizontal spacing being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display. In addition, the transparent display comprises a second layer positioned on the second side of the second glass substrate. The second layer comprises a plurality of light-absorbing elements, each of the plurality of light-absorbing elements being aligned from the front to the back of the transparent display with a corresponding pixel emitting structure of the plurality of pixel emitting structures in the first layer. The plurality of light-absorbing elements are configured to absorb light reflected from the first glass substrate. Furthermore, a thickness of the first glass substrate and the horizontal spacing between adjacent pixel emitting structures are configured such that a portion of light emitted from the one or more light-emitting components of a first pixel emitting structure that is reflected off the first glass substrate is blocked by the non-transmissive region of an adjacent second pixel emitting structure. The second layer is further configured to absorb reflected light that passes around the non-transmissive region of the plurality of pixel emitting structures to further reduce an amount of light visible from the back of the transparent display.

[0029] In some embodiments, the plurality of light-absorbing elements are aligned with the non-transmissive regions of the plurality of pixel emitting structures.

[0030] In some embodiments, the thickness of the first glass substrate is configured to cause light emitted from the first pixel emitting structure at a first range of reflection angles to be reduced by the non-transmissive region of the adjacent second pixel emitting structure. The first range of reflection angles including angles extending from 55 degrees to 90 degrees relative to the back of the transparent display. Furthermore, in some embodiments, a thickness of the second glass substrate is selected to position the plurality of light-absorbing elements to absorb light at a second range angle. The second range of angles being from approximately 1 degrees to 90 degrees relative to the back of the transparent display. The positioning of the plurality of light-absorbing elements is determined relative to the horizontal spacing of the plurality of pixel emitting structures.SP24-281

[0031] In some embodiments, the first glass substrate comprises an anti-reflective coating on the first side of the first glass substrate. The anti-reflective coating on the first side of the first glass substrate configured to reduce reflection of light at a third range of reflection angles. The third range of reflection angles is from 0 degrees to approximately 70 degrees relative to the back of the transparent display.

[0032] In another example embodiment, a method of making a transparent display is provided. The method comprises providing a first glass substrate comprising a first side and a second side and providing a second glass substrate comprising a first side and as second side. The method also comprises positioning a first layer between the second side of the first glass substrate and the first side of the second glass substrate. The first layer comprises a plurality of pixel emitting structures, each pixel emitting structure of the plurality of pixel emitting structures comprising one or more light-emitting components and a non-transmissive region. The non-transmissive region includes the one or more light-emitting components and an area surrounding the one or more light-emitting components. The plurality of pixel emitting structures are arranged with a horizontal spacing between adjacent pixel emitting structures. The horizontal spacing being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display. The method further comprises positioning a second layer on the second side of the second glass substrate. The second layer comprises a plurality of light-absorbing elements. The method further comprises aligning the plurality of light-absorbing elements from the front to the back of the transparent display with a corresponding pixel emitting structure of the plurality of pixel emitting structure in the first layer. The method also comprises selecting a thickness of the first glass substrate based on the horizontal spacing between the adjacent pixel emitting structures of the plurality of pixel emitting structures, such that a portion of the light emitted from the one or more lightemitting components of a first pixel emitting structure that is reflected off the first glass substrate is blocked by the non-transmissive region of an adjacent second pixel emitting structure. The second layer is further configured to absorb reflected light that passes around the non-transmissive region of the plurality of pixel emitting structures to further reduce an amount of light visible from the back of the transparent display.BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:SP24-281

[0034] FIG. 1 A is a front view illustrating an example transparent display, in accordance with some embodiments discussed herein;

[0035] FIG. IB is a rear view illustrating the example transparent display of FIG. 1 A, in accordance with some embodiments discussed herein;

[0036] FIG. 2 is a schematic view illustrating a pixel arrangement and structure in a transparent display, in accordance with some embodiments discussed herein;

[0037] FIG. 3 is a cross-sectional view illustrating a transparent micro-LED display and light paths in the transparent display, in accordance with some embodiments discussed herein;

[0038] FIG. 4 is a line graph illustrating normalized intensity of backlight leakage versus viewing angle relative to a transparent display back surface with and without anti-reflective coating, in accordance with some embodiments discussed herein;

[0039] FIG. 5 is a scatter plot illustrating the angles at which backlight leakage is minimized for different ratios of front cover thickness to pixel spacing, in accordance with some embodiments discussed herein;

[0040] FIG. 6 is a line graph illustrating the relationship between front cover thickness and angle difference between adjacent minimums (valleys) in backlight leakage, in accordance with some embodiments discussed herein;

[0041] FIG. 7 is a line graph illustrating reflectance versus angle for various anti- reflective coating configurations, in accordance with some embodiments discussed herein;

[0042] FIG. 8 is a line graph illustrating normalized intensity versus viewing angle for various ratios of front cover thickness to pixel spacing without anti-reflective coating, in accordance with some embodiments discussed herein;

[0043] FIG. 9 is a line graph illustrating normalized intensity versus viewing angle for various ratios of front cover thickness to pixel spacing with a standard anti-reflective coating, in accordance with some embodiments discussed herein;

[0044] FIG. 10 is a line graph illustrating normalized intensity versus viewing angle for various ratios of front cover thickness to pixel spacing with an optimized anti-reflective coating, in accordance with some embodiments discussed herein;

[0045] FIG. 11A is a cross-sectional view illustrating light paths in a transparent display with a black matrix layer, in accordance with some embodiments discussed herein;

[0046] FIG. 1 IB is a cross-sectional view illustrating light paths in a transparent display with multiple black matrix layers, in accordance with some embodiments discussed herein;SP24-281

[0047] FIG. 11C is a cross-sectional view illustrating light paths in a transparent display with multiple black matrix layer at an increased spacing relative to the pixel spacing, in accordance with some embodiments discussed herein;

[0048] FIG. 12 is a line graph illustrating normalized intensity versus viewing angle for various configurations of anti-reflective coating and black matrix layers, in accordance with some embodiments discussed herein;

[0049] FIG. 13 is a cross-sectional view illustrating light paths in a transparent display with a wire mesh structure layer, in accordance with some embodiments discussed herein; and

[0050] FIG. 14 is a flow chart illustrating an example method for making a transparent display with reduced backlight leakage, in accordance with some embodiments discussed herein.DETAILED DESCRIPTION

[0051] Exemplary embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the present disclosure are shown. Indeed, the present disclosure may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout.

[0052] A front view illustrating an example transparent display 100 is provided in FIG. 1A. The transparent display 100 represents a broad category of visual output devices that allow viewers to see through the display while simultaneously presenting visual information. Such displays find applications in various fields, including but not limited to, augmented reality systems, smart windows, vehicular head-up displays, and public information systems. The transparent display 100 comprises a transparent or translucent display area 104 enclosed, in some embodiments, within a frame or housing 102. The display area 104 is the region where visual information is presented to the user and is configured to render images and virtual objects that may appear to be in a real -world space. The display area 104 is shown presenting a pie chart, exemplifying the type of information that can be displayed. However, it should be understood that the content displayed is not limited to this example and can include any form of visual information, including text, images, videos, or interactive elements. The transparent display 100 may also be configured to sense user input, such asSP24-281 movement of a user’s hand, to interact with the one or more of the virtual interactive elements and to generate input based on the movement.

[0053] A notable feature of the transparent display 100 is its ability to maintain transparency while displaying information. This is achieved through the use of advanced display technologies such as micro-LED or OLED, which allow for individual pixels to be selectively illuminated while maintaining transparency in non-illuminated areas. The transparency of the display is demonstrated by the visibility of a user 108 positioned behind the display, whose hand can be seen through the display area 104.

[0054] The ability to see the user 108 through the display area 104 while simultaneously presenting visual information (such as the pie chart) illustrates the dual functionality of the transparent display 100. This enables applications in, for example, augmented reality, smart windows, and other scenarios, where maintaining awareness of the environment behind the display may be important.

[0055] The frame or housing 102 may serve multiple purposes. The frame or housing 102 may provide structural support for the display components, and house necessary electronics and connections which may include but not limited to processor(s), and computer readable media such as memory media and storage media. The frame or housing 102 may also include user interface elements such as power buttons or touch-sensitive areas for controlling the display.

[0056] While FIG. 1 A shows a rectangular display, it should be understood that the principles of the present disclosure may be applied to displays of various shapes and sizes, including curved or non-planar displays. The specific dimensions and aspect ratio of the display can be tailored to suit particular applications or user requirements.

[0057] FIG. IB illustrates a rear view of the exemplary transparent display 100 shown in FIG. 1A, providing details into how the display appears from behind and demonstrating its privacy features.

[0058] From this perspective, unlike the front view in FIG. 1A, the rear view does not show the displayed content (such as the pie chart), illustrating how the display is configured to present information primarily to viewers on the front side. While the display enables see- through visibility from the front, it is configured to minimize the visibility of displayed content from the back, addressing privacy concerns and reducing backlight leakage.

[0059] One of the challenges that may be faced in transparent displays is of backlight leakage. Backlight leakage occurs when light from the display's illuminated pixels is reflectedSP24-281 or scatered within the display structure, becoming visible from the rear of the display. This phenomenon can compromise both the privacy of the displayed information and the clarity of the view through the display. To address this challenge, different features may be included such as specially designed covers, optimized anti-reflection coatings, and strategically placed light-absorbing elements. These elements may work in concert to minimize backlight leakage, particularly at large viewing angles, without compromising the display's transparency or resolution.

[0060] While not visible in this rear view, the display may incorporate several features to reduce backlight leakage. These include specially designed covers, optimized anti-reflection coatings, and strategically placed light-absorbing elements. These features work together to minimize the amount of light from the display's pixels that might otherwise be visible from the back, ensuring privacy and improving the overall viewing experience.

[0061] The back view also emphasizes the potential for the transparent display 100 to be seamlessly integrated into various environments. Whether used as a standalone unit or incorporated into existing structures like windows or partitions, the display's ability to maintain transparency from both the front and the back while providing privacy from the back ensures it doesn't obstruct or significantly alter the existing visual landscape when not actively displaying information.

[0062] The front view (FIG. 1A) and rear view (FIG. IB) of the transparent display 100 illustrate the dual objectives of maintaining clarity and visibility of displayed information from the front while minimizing backlight leakage and enhancing privacy from the back. This balance supports the implementation of transparent displays in various applications, from public information systems to smart windows. The display incorporates several features to achieve this balance, including profiled covers, anti-reflective coatings, and light-absorbing elements.

[0063] FIG. 2 illustrates a schematic view of a pixel arrangement and structure in a transparent display 150, providing a look at the components that enable the display's functionality while addressing backlight leakage challenges.

[0064] At the foundation of the display is the substrate 152. The substrate is the base material upon which the entire display is built. It plays a role in the display's performance, providing both structural support and influencing the optical properties of the overall device. Substrates for transparent displays balance several characteristics including transparency, refractive index, and thickness. The transparency determines how much light can passSP24-281 through the material, while the refractive index affects how light bends when passing through the substrate. The thickness of the substrate influences both the mechanical properties of the transparent display and the transparent display’s optical characteristics. In transparent displays, common substrate materials include various types of glass and transparent polymers. Each material offers different benefits in terms of optical properties, durability, flexibility, and manufacturing compatibility.

[0065] Built upon the substrate is the pixel array 154. The pixel array comprises the lightemitting elements that form the image on a transparent display. In transparent displays, the design of this array enables not only the image quality but also for maintaining transparency when the display. The pixel array's design may consider factors such as pixel density, to determine the resolution of the display; pixel size and spacing, where both the size and spacing may affect both image quality and the transparent display's transparency; and microLED or OLED arrangement, illustrating how the color components are arranged within each pixel and how it may impact color reproduction and overall display performance. These elements collectively determine the resolution, image quality, and transparency of the display.

[0066] Each pixel 160 in the array 154 may comprise multiple micro-LEDs functioning as light-emitting components. Pixel 160 may comprise: a red micro-LED 166, a green microLED 164, and a blue micro-LED 162. This RGB (Red, Green, Blue) configuration creates full-color images, as these three primary colors can be combined to produce a wide range of colors. The size, spacing, and arrangement of these micro-LED within each pixel may also impact both image quality and the display's transparency.

[0067] Various color models and micro-LED arrangements can be employed, each with its own advantages. However, an additional micro-LED may reduce the pixel density if the overall pixel size remains constant. The choice of color model and micro-LED arrangement in a transparent display would depend on various factors including the desired color gamut, energy efficiency, manufacturing complexity, and the specific transparency requirements of the application. Each arrangement would require optimization of the micro-LED sizes, spacing, and driving algorithms to balance color reproduction, resolution, and transparency.

[0068] The micro-LEDs are small light-emitting diodes, typically measuring less than 100 micrometers. Their small size allows for high-resolution displays while maintaining transparency in the non-emitting areas. The size, efficiency, and optical characteristics of these micro-LEDs also impact the display's performance.SP24-281

[0069] In some embodiments, the light-emitting components within each pixel may comprise micro-LEDs with quantum dot color converters (QDCC), where blue micro-LEDs are combined with quantum dot color converters to generate the desired colors. In some embodiments, the light-emitting components within each pixel may be an Organic Light Emitting Diodes (OLEDs), Quantum Dot Light Emitting Diodes (QLEDs), or Transparent Liquid Crystal Displays (LCDs). Each of these technologies require different considerations in terms of pixel structure, driving electronics, and overall display design. The choice between micro-LEDs, OLEDs, QLEDs, LCDs, QDCCs, or other emerging technologies depend on the specific requirements of the application, including factors such as brightness, power efficiency, lifetime, color reproduction, and manufacturing cost.

[0070] The overall structure of the pixel array 154, including the size and spacing of pixels and micro-LEDs, determines several characteristics of the display, for example, the pixel pitch 153 is the distance between the centers of adjacent pixels 160, which directly relates to the display's resolution. In some embodiments, the pixel pitch 153 may range from 100pm to 500pm. The RGB micro-LEDs may also be placed at a distance 163 between each other in a way that may affects color mixing and overall image quality. In some embodiments, this distance may be 25 micrometers from each micro-LED. The fdl factor, which is the ratio of the light-emitting area to the total pixel area, may also impact both display brightness and transparency.

[0071] The pixel array 154 may have a length 158 and a width 156. In some embodiments, the length 158 and the width 156 may range from 5mm to 400mm, with larger displays being created by tiling multiple arrays together. Additionally, each individual red, blue, and green micro-LEDs may have a height 167 and a width 165, where, in some embodiments, the height may range from 5 pm to 60 pm and the width may range from 5 pm to 60pm. This uniformity in size across red, green, and blue emitters simplifies manufacturing while still allowing for color-specific optimizations through other means, such as driving current or LED composition. The relatively small size of the micro-LEDs compared to the overall pixel size contributes to the display's transparency. These dimensions may help in the balance of image quality with the need for transparency in non-emitting areas.

[0072] While not visible in the schematic, the display structure may also include optical clear adhesive (OCA) layers. These layers may be configured to bond components together while maintaining optical clarity. In some embodiments, the OCA might have a refractiveSP24-281 index of 1.52 at 550nm, with a transmission of 99.27% over a 5mm thickness. The properties of these OCA layers help in maintaining optical performance across the entire display.

[0073] This pixel structure and arrangement form the basis for advanced optical modeling, including ray tracing simulations. These models allow designers to predict and optimize the display's performance, particularly in managing backlight leakage while maintaining high image quality and transparency. By adjusting parameters such as layer thicknesses, refractive indices, and micro-LED dimensions, designers can fine-tune the display's characteristics for specific applications.

[0074] Alternative embodiments explore additional / different configurations to address specific needs. For instance, in some embodiments, a high-resolution transparent display version might use a smaller pixel pitch, perhaps 100pm, with correspondingly smaller microLEDs and tighter micro-LED spacing. Conversely, a large-format display intended for viewing at a distance might use a larger pixel pitch, balancing resolution with transparency, manufacturing cost and power efficiency.

[0075] The combination of these various elements and potential configurations demonstrates the flexibility and potential of this transparent display design. By balancing and optimizing these components, the transparent display may be tailored to meet the specific requirements of diverse applications, from consumer electronics to specialized industrial or medical uses, all while addressing the challenge of backlight leakage in transparent displays.

[0076] Moving on, FIG. 3 illustrates a cross-sectional view of a transparent display 200, demonstrating how the inherent geometry of the display can be leveraged to control unwanted backlight emission at various angles by controlling the path of light within the display structure to minimize backlight leakage while also maintaining the display's primary functions. By configuring the relationship between specific components, it becomes possible to manipulate how light reflects within the transparent display 200, effectively reducing unwanted light emission from the back of the display.

[0077] The transparent display 200 is oriented in a three-dimensional space defined by an x-axis that runs horizontally across the width of the display, the y-axis that extends vertically along the height of the display, and the z-axis that runs perpendicular to the display surface from front of the display 208 to the back of the display 210. Where the front of the display 208 faces a viewer and the back of the display 210 is the side opposite to the viewer. This three-dimensional coordinate system is used consistently throughout this application unless explicitly stated otherwise.SP24-281

[0078] At the front of the display is the front cover 202 (e.g., a first glass substrate). This component may be configured to protect the internal elements of the display 200 and provide a smooth surface for potential touch interactions. The front cover 202 may also be configured to manage light paths within the display where the thickness of the front cover 202, denoted as tr, is a parameter in managing backlight leakage. This thickness, in relation to other display parameters, directly influences the path of reflected light within the display structure.

[0079] Behind the front cover 202 may also be a layer of optical clear adhesive (OCA) 206. The OCA 206 is configured to bond the various components of the display together while maintaining optical clarity. The refractive index and thickness of the OCA 206 may also contribute to the overall optical properties of the display stack.

[0080] The pixels 205 containing light-emitting elements of the display, e.g., microLEDs, may be positioned behind the OCA 206. Each pixel 205 is capable of emitting light to form a display for the transparent display 200. The pixels 205 may be positioned such that the pixels may be designated as 205ai through 205axwhere “x” represents the total number of pixels shown. For example, if there are eight pixels, they would be labeled as 205ai, 205a2, 205as and so on, up to 205as. The pixels 205 are arranged in a regular pattern, with a distance between the centers of adjacent pixels defined as the pixel pitch, denoted by p. The pixels 205 may be fabricated on or transferred to the surface of a second substrate 204. This substrate provides structural support for the pixels and may incorporate the necessary electrical connections to drive the light-emitting elements. The second substrate 204 may be made of similar materials to the front cover 202 (e.g., it may form a second glass substrate), and / or it may be a specialized substrate optimized for the fabrication or transfer of micro-LED elements. Each pixel 205 (205ai to 205ax) comprises both light-emitting areas and non- transmissive regions 230. The non-transmissive regions may include the micro-LED structures, associated electronics, and any opaque materials used in the pixel construction. These non-transmissive regions may be strategically used to the blocking of certain light paths.

[0081] Behind the pixels 205 is the second substrate 204 which may be configured as a back cover. The second substrate 204 may provide additional structural support and protection for the display components. Between the pixels 205 and the second substrate 204, another layer of OCA may be present, further contributing to the optical properties of the display stack. These optical properties influence the behavior of light as it travels through the display structure.SP24-281

[0082] When a pixel 205 emits light, represented by ray 250, it travels through the OCA layer 206 and enters the front cover 202. Upon reaching the interface between the front cover 202 and the air as shown at points 220 and 222, a portion of this light is transmitted, forming the useful display output visible to the viewer. However, due to the difference in refractive indices between the front cover material and air interface 220 and 222, a portion of the light is reflected back into the display structure. This reflected light, represented by rays 251, travels back through the front cover 202 towards the pixels 205.

[0083] Depending on the angle of reflection and the ratio of the front cover thickness (tr) to the pixel pitch (p), these reflected rays may intersect with neighboring pixels. If a ray intersects with the non-transmissive region of a neighboring pixel, it is blocked / absorbed, preventing it from contributing to backlight leakage.

[0084] The angle between a reflected ray and a line perpendicular to the display surface determines whether a reflected ray will be blocked by a neighboring pixel. This angle is related to the display geometry and can be described using a function of the view angle. The view angle, denoted as 0i, represents the angle at which light emerges from the display relative to a perpendicular direction of a viewing direction of the transparent display 200. The relationship between the view angle and the display geometry can be expressed using a sine function. This function describes the angles at which "valleys" (minima) occur in the backlight leakage intensity distribution. These valleys correspond to angles where the blocking effect of non-transmissive pixel areas is most effective. As such, the reduction in the amount of light leakage viewable from the back of the transparent display occurs at a function of a view angle, 0; wherein the function of view angle is determined by: 0; = sin-1[— sin ( 90° — tan-1(— ) lwhere tf is the thickness of the front cover, where p is the horizontal spacing between adjacent pixel comprising light-emitting structures, where no is a refractive index of the surrounding medium, and where ni is the refractive index of the front cover material.

[0085] By manipulating the tr / p ratio, the angles at which these valleys occur can be controlled, effectively shaping the angular distribution of backlight leakage. The refractive index of the front cover material plays a role in this equation as well. Typical materials used for the front cover, such as various types of glass or transparent polymers, have refractive indices ranging from about 1.45 to 1.9. The refractive index no of the surrounding medium is typically that of air, which is approximately 1.0. The substantial difference between and no is what causes the reflection at the front cover-air interface at 220 and 222.SP24-281

[0086] The front cover thickness tr is a design parameter that can be adjusted to optimize the backlight leakage management. Typical values may range from 0.1 to 1.0 millimeters, depending on the specific display requirements and manufacturing constraints. In some embodiments the values may range from .05 to 5 millimeter. The pixel pitch p is determined by the resolution requirements of the display. In micro-LED displays, this can range from tens to hundreds of micrometers. The choice of pixel pitch affects not only the display resolution but also the backlight leakage characteristics through its influence on the tr / p ratio.

[0087] By analyzing this equation, it can be seen that decreasing the tf / p ratio (i.e., increasing the front cover thickness relative to the pixel pitch) causes the increasing of the separation between the valleys. This is beneficial as it shifts the angles of high backlight leakage intensity to angle regions where they can be more effectively suppressed such as by anti -reflective coatings.

[0088] The sine and inverse sine functions in the equation account for the refraction of light as it passes between media with different refractive indices (the front cover material and air). This refraction is what enables manipulation of the light paths within the display structure. The tangent function in the equation relates to the geometry of the light path within the front cover. It describes how the light travels between reflections off the front and back surfaces of the cover. The 90° term in the equation represents the perpendicular angle to the display surface. The subtraction of the arctangent term from 90° gives the complement of the angle at which light reflects off the back surface of the front cover.

[0089] By adjusting the tr / p ratio, display designers can control the angular distribution of backlight leakage. The optimization of the tr / p ratio can potentially provide better suppression of backlight leakage across a wider range of viewing angles, and shifts the angles of high backlight leakage intensity to angle regions where they can be more effectively suppressed such as by anti-reflective coatings.

[0090] However, because the tr / p ratio is relative to the front cover thickness and the display resolution (or pixel pitch) the optimizing of a transparent display involves balancing the backlight leakage management with other factors such as display resolution, device rigidity, thickness and weight.

[0091] It's important to note that while this equation describes the angles of minimum backlight leakage (the valleys), the actual intensity of backlight leakage at these angles is not zero. Some light may still escape due to factors such as scattering, imperfections in the display structure, or light paths not accounted for by this simplified model.SP24-281

[0092] The overall transparency of the display is not significantly affected by this backlight leakage management. The transparency is primarily determined by the fill factor of the pixel array (the ratio of light-emitting area to total area) and the transmittance of the various layers in the display stack.

[0093] In addition to managing backlight leakage, this approach to managing backlight leakage may also help to reduce other optical artifacts in transparent displays, such as ghost images and internal reflections. By controlling the paths of reflected light within the display, it's possible to minimize these unwanted effects and improve overall image quality.

[0094] While this backlight management is particularly well-suited to micro-LED displays due to their small emitter size, it can also be applied to other types of transparent displays, such as those based on OLED or LCD technology. The specific implementation details may vary depending on the display technology, but the underlying principles remain the same.

[0095] Combining this geometric approach to backlight leakage management with other optical treatments, such as anti-reflective coatings and / or polarizers, may lead to further improvements in display performance. The geometric approach may be particularly effective at large angles where anti-reflective coatings are less effective, while anti-reflective coatings can provide additional suppression of backlight leakage at near-normal angles.

[0096] In some embodiments, the design of the non-transmissive regions 230 of the pixels 205 may be optimized to enhance the effectiveness of this approach. For example, the edges of these areas could be shaped or textured to further control the paths of reflected light. For tiled display applications, where multiple smaller displays are combined to form a larger display, this control of backlight leakage can help to minimize visible seams between tiles by reducing light leakage at the edges of each tile.

[0097] Temperature variations may also affect the refractive indices and dimensions of the display components, potentially altering the backlight leakage characteristics. In some embodiments, materials with low thermal expansion coefficients may be used for the front cover to minimize these effects. Additionally, active temperature compensation mechanisms may be implemented to adjust display parameters in response to temperature changes.

[0098] In some embodiments, gradient-index materials may be incorporated in the front cover to provide additional control over light paths. These materials, which have a refractive index that varies gradually across their thickness, may allow for even more precise management of backlight leakage.SP24-281

[0099] In some embodiments, this backlight leakage management approach may be adapted for use in curved or flexible transparent displays. For curved displays, the equation describing the angles of backlight leakage minima may be modified to account for the curvature of the display surface. In flexible displays, dynamic adjustment of display parameters may be implemented to maintain optimal backlight leakage management as the display flexes.

[0100] FIG. 4 illustrates a line graph depicting the normalized luminous intensity of light leaking from the back of the transparent display as a function of viewing angle. The graph presents data for two configurations of a transparent display: one without AR coating and one with AR coating applied to the front cover surface.

[0101] The horizontal axis represents the viewing angle, measured in degrees, relative to the transparent display's back surface. The range extends from 0 degrees, corresponding to a perpendicular view of our display, to 90 degrees, representing a view parallel to the display surface. On the vertical axis, the graph depicts the normalized luminous intensity of backlight leakage from the transparent display. This normalization allows for direct comparison between the two configurations, with a value of 1.1 indicating the maximum observed intensity within the measured range.

[0102] Both curves in the graph represent the transparent display configuration where the ratio of front cover thickness (tr) to the display pixel pitch (p) is 7.0. The solid line depicts the backlight leakage for the display without AR coating, while the dashed line represents the display with AR coating applied. The curve for the display without AR coating exhibits a periodic pattern. This periodicity is a direct result of the approach to backlight leakage management, where light leaking from the back side is repeatedly blocked by the non- transmissive regions of the pixels. The distance between these periodic features, labeled as Wp, corresponds to the angular separation between successive intensity peaks or valleys in the display.

[0103] Several prominent peaks, labeled as "issue peaks," are visible in the graph, particularly at higher viewing angles. These peaks represent angles where backlight leakage is most pronounced in the transparent display. This backlight leakage may be managed by shifting them to smaller angles where they can be more effectively mitigated.

[0104] The curve representing the display with AR coating demonstrates a reduction in backlight leakage intensity, especially at lower viewing angles. This reduction is most evidentSP24-281 for angles below approximately 55 degrees, where the AR coating effectively suppressing a large portion of the backlight leakage.

[0105] The graph also reveals the behavior of the AR coating at higher angles. For incident angles larger than about 55 degrees, the reflection from the AR coated surface increases. As a result, the suppression of backlight leakage at viewing angles exceeding 65 degrees is less pronounced compared to lower angles.

[0106] The periodic nature of the backlight leakage persists in both curves for the display, though it is less pronounced in the AR-coated configuration. This persistence demonstrates that while the AR coating reduces overall leakage, as it works in conjunction with the geometric placement of pixels to manage the backlight leakage to achieve optimal performance.

[0107] This graph illustrates the effectiveness of the combined approach to backlight leakage management. By integrating both geometric placement of pixels and carefully choosing a front cover thickness (as evidenced by the periodic pattern) and AR coating, the display achieves reduction in backlight leakage across a wide range of viewing angles.

[0108] FIG. 5 is a scatter plot illustrating the angles at which valleys occur in the backlight leakage intensity distribution for a transparent display. These valleys represent points of minimum backlight leakage intensity and are plotted as a function of their order for various ratios of front cover thickness to pixel pitch.

[0109] The horizontal axis of the plot represents the order of the backlight leakage valley, ranging from 1 to 12. Each point on this axis corresponds to a successive valley in the angular distribution of backlight leakage intensity. The vertical axis represents the angle, measured in degrees, at which each valley occurs. This angle is measured relative to the normal of the display surface, with 0 degrees corresponding to the direction perpendicular to the display and 90 degrees being parallel to the display surface.

[0110] The plot displays five data series corresponding to different ratios of front cover thickness to pixel pitch (tr / p): 7.000, 5.570, 4.250, 2.850, and 1 .425. For all data series, the refractive index of the surrounding medium (no) is 1.00, corresponding to air, and the refractive index of the front cover material (ni) is 1.51, typical of display glass. Each data series shows a trend: as the order of the valley increases, the angle at which valley occurs increases.

[0111] For the highest tr / p ratio of 7.000, the angles of the valleys span a wide range. The first valley occurs at approximately 5 degrees, while the 12th valley is found at about 80SP24-281 degrees. This series shows an increase gradually in valley angle with increasing order. In contrast, the lowest tr / p ratio of 1.425, shows a much smaller span of angles. The first valley for this ratio occurs at 30 degrees, while the second valley is found at approximately 60 degrees. The intermediate ratios (5.570, 4.250, and 2.850) fall between these two extremes, illustrating a continuous relationship between the tf / p ratio and the angular distribution of backlight leakage valleys.

[0112] This plot demonstrates how the ratio of front cover thickness to pixel pitch influences the angular distribution of backlight leakage in the transparent display. A higher ratio results in more numerous valleys spanning a wider range of angles, while a lower ratio produces fewer valleys at larger angles. The information may help in backlight leakage management of transparent display. By adjusting the tf / p ratio, the angles at which minimum backlight leakage occurs can be controlled, allowing for tailored performance in different viewing angle ranges.

[0113] The relationship between the tf / p ratio and the valley angles is governed by the equation discussed in relation to FIG. 3:= sin-1[~sin ^90° — tan-1( ^) Jwhere Oi is the angle of the zth valley, and no are the refractive indices of the front cover and surrounding medium respectively, tf is the front cover thickness, and p is the pixel pitch.

[0114] This plot provides a visual representation of how this equation manifests for different tf / p ratios, offering insights into the behavior of backlight leakage in the transparent display across a range of design parameters.

[0115] FIG. 6 is a line graph illustrating the relationship between a front cover thickness and an angle difference between adjacent valleys in the backlight leakage intensity distribution of a transparent display. Specifically, the graph shows how the angular separation between the valley occurring at approximately 60 degrees and its adjacent lower valley changes as a function of the front cover thickness.

[0116] The horizontal axis represents the thickness of the front cover, measured in micrometers (pm). The range extends from 200 pm to 1500 pm, covering a wide spectrum of possible front cover thicknesses fortransparent displays. The vertical axis represents the angle difference, measured in degrees, between the valley at approximately 60 degrees and its adjacent lower valley in the backlight leakage intensity distribution. This angle difference provides insight into the spacing of backlight leakage minima in the angular domain.

[0117] The graph depicts a single curve showing an inverse relationship between the front cover thickness and the angle difference between adjacent valleys. As the front coverSP24-281 thickness increases, the angle difference between these specific valleys decreases. For this graph, the refractive index of the surrounding medium (no) is 1.00, corresponding to air, and the refractive index of the front cover material (m) is 1.51, typical of display glass. These values are consistent with those used in FIG. 5.

[0118] The curve shows a rapid decrease in angle difference for front cover thicknesses between 200 pm and approximately 850 pm. In this range, the angle difference drops from about 30 degrees to approximately 10 degrees. For front cover thicknesses greater than 850 pm, the rate of decrease in angle difference slows considerably. The curve asymptotically approaches a minimum angle difference of about 6 degrees as the front cover thickness nears 1500 pm.

[0119] This graph illustrates how the front cover thickness influences the angular distribution of backlight leakage minima in the transparent display. By controlling the front cover thickness, the spacing between valleys in the backlight leakage intensity distribution can be adjusted. The relationship illustrated in this graph is closely tied to the ratio of front cover thickness (tr) to pixel pitch (p) discussed in relation to FIG. 5. Changing the front cover thickness while keeping the pixel pitch constant effectively alters this ratio, leading to the changes in valley spacing observed in the graph. By adjusting the front cover thickness, the angular separation between valleys can be controlled, allowing for optimization of backlight leakage suppression in specific angular ranges.

[0120] This graph, in conjunction with the data presented in FIG. 5, demonstrates how the geometric parameters of the transparent display can be tuned to modify the angular distribution of backlight leakage. By controlling the ratio of front cover thickness to pixel pitch, the locations of luminous intensity modulation in angular space can be adjusted.

[0121] The ability to move the "issue peaks" (high order peaks, particularly those at angles higher than approximately 60 degrees) to lower viewing angles helps in the backlight leakage management in the transparent display. This shift allows for greater suppression of these peaks by anti-reflective (AR) coatings, which are typically effective at smaller angles. Furthermore, this approach enables management of the intensity modulation period (Wp) to suppress backlight leakage at viewing angles larger than approximately 60 degrees, particularly in the angle range higher than 70 degrees, which is challenging to suppress using AR coatings alone.

[0122] In addition to these geometric considerations, the transparent display incorporates optimized AR coatings to further reduce backlight leakage. For a color transparent displaySP24-281 consisting of red, green, and blue emitters, the AR coating is optimized to minimize the effective reflectance across the emission peaks of these emitters.

[0123] The effective reflectance at a given incident angle a is defined as: 7? (AR, Ag, Ag, a) = CRRR (AR, a ) + CGRG(Ag, a )+ CBRB(Ag, a ) with CR + CG+ CB= 1

[0124] where R R (A R , a) is reflectance of AR coating at the red peak wavelength A R , for incident angle a, R (A , a) is reflectance of AR coating at the green peak wavelength A , for incident angle a, Rfi(A a) is reflectance of AR coating at the blue peak wavelength A , for incident angle a, C is the ratio of red emitter power to the total power of red, green, and blue emitters for generating white screen, C is the ratio of green emitter power to the total power of red, green, and blue emitters for generating white screen, CBis the ratio of blue emitter power to the total power of red, green, and blue emitters for generating white screen. Unlike conventional AR coatings, the optimization of the AR coating performance considers both the incident angle range around the normal and the angle range around approximately 60 degrees. The wavelengths of red, green, and blue peaks (XR, XG, XB) for the optimizations of AR coatings are approximately 630±20nm, 532±20nm, and 465±20nm, respectively.

[0125] The equation for effective reflectance represents a weighted sum of the reflectances for each color component of the display. This approach accounts for the fact that different wavelengths of light may interact differently with the AR coating, and that the relative intensities of red, green, and blue emitters may vary to produce a white screen.

[0126] In this equation, R (A a), R (A a), and R (A a) R R G G B B represent the reflectance of the AR coating for red, green, and blue light respectively, at a given incident angle a. These terms capture how the AR coating's performance varies with both wavelength and viewing angle. The coefficients CR, CG, and CB represent the relative power contributions of each color emitter when producing a white screen. These coefficients sum to 1, ensuring that the equation represents a properly weighted average of the reflectance. By minimizing this effective reflectance across a range of incident angles, particularly around normal incidence and around 60 degrees, the AR coating can be optimized to complement the geometric backlight leakage management approach.

[0127] The combination of the geometric approach illustrated in FIG. 6 and the optimized AR coating enables suppression of backlight leakage in the transparent emissive display across all viewing angles.SP24-281

[0128] Referring now to FIG. 7, a line graph illustrates the reflectance characteristics of the front surface of the front cover in a transparent display under various conditions. The graph demonstrates how different surface treatments affect light reflection across a range of incident angles.

[0129] The horizontal axis represents the incident angle of light, measured in degrees, ranging from 0 to 95 degrees. An incident angle of 0 degrees corresponds to light approaching the surface perpendicularly, while 90 degrees represents light almost traveling parallel to the surface. The vertical axis shows the reflectance as a percentage, ranging from 0% to 40%. Reflectance in this context refers to the proportion of incident light that is reflected from the front surface of the front cover.

[0130] Three curves are presented in the graph, each representing a different surface condition of the front cover. The first curve shows the reflectance of the front surface without any anti-reflective (AR) coating. This curve serves as a baseline, illustrating the natural reflective properties of the front cover material.

[0131] The second curve represents the reflectance when AR coating 1 is applied to the front surface. AR coating 1 may be a standard anti -reflective treatment designed to reduce reflections across a range of incident angles.

[0132] The third curve illustrates the reflectance when AR coating 2 is applied. AR coating 2 may be an advanced anti -reflective treatment specifically optimized for the transparent display to manage backlight leakage effectively.

[0133] For all three curves, the incident light used for measurement consists of three wavelengths corresponding to red (XR = 630nm), green ( G = 550nm), and blue ( B = 465nm) light. These wavelengths are combined with equal power ratios and representing the typical color components in a display where red ( R = 630nm) shows the front surface without AR coating, green ( G = 550nm) with AR coating 1, and blue (XB = 465nm) with AR coating 2.

[0134] Without AR coating, the reflectance remains relatively constant at about 4% for incident angles up to approximately 50 degrees, after which it increases rapidly. AR coating 1 significantly reduces reflectance for near-normal incidence, keeping it at approximately 1% up to about 30 degrees. However, its effectiveness diminishes at higher angles, with reflectance increasing rapidly beyond 60 degrees. AR coating 2 demonstrates superior performance across a wider range of angles. It maintains low reflectance (below 0.5%) up to about 45 degrees and shows a more gradual increase in reflectance at higher angles compared to AR coating 1.SP24-281

[0135] While standard AR coatings (represented by AR coating 1) provide improvements over uncoated surfaces, they may not adequately address the unique requirements of transparent displays, particularly at high viewing angles. The optimized AR coating (AR coating 2) shown in this graph may complement the geometric backlight leakage management approach discussed in relation to previous section herein. By maintaining low reflectance across a wide range of incident angles, including those around 60 degrees where geometric management becomes challenging, AR coating 2 contributes to backlight leakage suppression in the transparent display.

[0136] FIGs. 8-10 are line graphs illustrating the normalized luminous intensity of back- leaking light as a function of viewing angle for a transparent display under various configurations. These figures demonstrate the combined effects of different front cover thickness to pixel pitch ratios (tf / p) and anti -reflective (AR) coatings on backlight leakage. The data presented in these figures is based on a series of modeling cases, the parameters of which are detailed in Table 1.

[0137] Table 1 presents the modeling parameters for nine cases, labeled Al through C3. These cases systematically explore the effects of varying front cover thickness, pixel pitch, and AR coating on backlight leakage in the transparent display.TABLE 1

[0138] In Table 1, the "Case #" column identifies each configuration. The cases are grouped into three sets (A, B, and C), each with three subcases (1, 2, and 3). The "Front cover thickness, tr (mm)" column specifies the thickness of the front cover for each case. Three thicknesses are considered: 1.4 mm for set A, 1.2 mm for set B, and 0.5 mm for set C. This variation in thickness allows for the exploration of how cover thickness affects backlight leakage. The "Pixel pitch, p (mm)" column indicates the distance between the centers ofSP24-281 adjacent pixels. In all cases, this value is held constant at 0.2 mm. Maintaining a consistent pixel pitch across all cases ensures that any observed differences in backlight leakage can be attributed to changes in other parameters. The "Ratio, tr / p" column presents the ratio of front cover thickness to pixel pitch. Three ratios are examined: 7.0 for set A, 6.0 for set B, and 2.5 for set C. These ratios are derived from the respective front cover thicknesses and the constant pixel pitch. The "Front surface of front cover plate" column specifies the type of surface treatment applied to the front cover. Three conditions are considered: No AR coating, AR coating 1, and AR coating 2. Within each set (A, B, C), these three conditions are systematically applied, allowing for the assessment of how different AR coatings interact with various tr / p ratios. The cases in Table 1 correspond directly to the curves presented in FIGs. 8-10.

[0139] FIG. 8 illustrates cases Al, Bl, and Cl, all without AR coating. This serves as a baseline, showing the inherent backlight leakage characteristics for each tr / p ratio without any additional surface treatment.

[0140] FIG. 9 presents cases A2, B2, and C2, all employing AR coating 1. This figure demonstrates the impact of a standard AR coating on backlight leakage for each tr / p ratio.

[0141] FIG. 10 displays cases A3, B3, and C3, all utilizing the improved AR coating 2. This figure showcases the enhanced backlight leakage suppression achieved with an optimized AR coating for each tf / p ratio.

[0142] In all three figures, the horizontal axis represents the viewing angle relative to the display back surface, ranging from 0 to 90 degrees. A viewing angle of 0 degrees corresponds to a line of sight perpendicular to the display surface, while 90 degrees represents a line of sight parallel to the display surface. The vertical axis in each graph shows the normalized luminous intensity of back-leaking light, with 1.0 representing the maximum intensity observed across all configurations and angles. This normalization allows for direct comparison between different cases and figures.

[0143] In FIG. 8, which presents cases without AR coating, all three curves exhibit a periodic pattern of peaks and valleys. This pattern is characteristic of the backlight leakage behavior in these displays. The distance between successive peaks, denoted as Wp, represents the periodic width of the backlight leakage intensity modulation. Notably, in FIG. 8, case Cl (tr / p = 2.5) shows a markedly different behavior compared to Al and Bl. One of the issue peaks is shifted to below 70 degrees, and the amplitude of the issue peak above 70 degrees isSP24-281 significantly reduced. This demonstrates how controlling the tf / p ratio can manipulate the periodic (Wp) and issue peak locations of the backlight leakage intensity modulation.

[0144] FIG. 9, presenting cases with AR coating 1, shows a general reduction in backlight leakage intensity across all viewing angles compared to FIG. 8. This reduction demonstrates the effectiveness of AR coating 1. In this figure, case C2 (tf / p = 2.5) provides the best suppression of backlight leakage, particularly in the large angle range. However, the suppression, while improved, may not yet be optimal.

[0145] FIG. 10, illustrating cases with the improved AR coating 2, shows further enhancement in backlight leakage suppression across all viewing angles compared to FIG. 9. Again, case C3 (tf / p = 2.5) provides the best suppression of backlight leakage, especially in the large angle range. The improvement from AR coating 1 to AR coating 2 is evident, with reduction in backlight leakage intensity across all angles.

[0146] Comparing the three figures reveals the cumulative benefits of combining optimal tf / p ratios with advanced AR coatings. The progression from no AR coating (FIG. 8) to AR coating 1 (FIG. 9) and finally to AR coating 2 (FIG. 10) shows a trend of improved backlight leakage suppression. It is noteworthy that in all three figures, the configuration with tf / p = 2.5 (cases Cl, C2, C3) consistently provides the best performance in terms of backlight leakage suppression, particularly at large viewing angles. This suggests that a lower tf / p ratio, combined with an optimized AR coating, may be an effective way in managing backlight leakage.

[0147] The modeling results presented in FIGs. 8-10 and Table 1 illustrate that the combination of engineering the ratio between front cover thickness and display pixel pitch, along with AR coating optimization, may effectively suppress backlight leakage in a transparent emissive display across all viewing angles.

[0148] The systematic exploration of different tf / p ratios and AR coatings, as presented in Table 1 and FIGs. 8-10, provides a comprehensive understanding of backlight leakage behavior in transparent displays. This understanding enables the displays to be configured with reduced unwanted light emission, thereby enhancing image quality and maintaining privacy across a wide range of viewing angles.

[0149] The preceding sections discussed geometric approaches combined with AR coatings in managing backlight leakage. FIG. 11A illustrates a cross-sectional view of a transparent display 300 that incorporates light-absorbing elements to manage backlight leakage. These light-absorbing elements may be implemented either alone or in combinationSP24-281 with the geometric approaches and AR coatings to provide additional control over unwanted light transmission while maintaining display transparency. The transparent display may comprise multiple layers, each serving a function in the overall operation and light management of the device.

[0150] The transparent display 300 may have a front side 310, which faces the viewer, and a back side 312, which is opposite to the viewer. The transparent display 300 is oriented in a three-dimensional space defined by an x-y-z plane. The x-axis extends horizontally across the width of the display, while the y-axis runs vertically along the height of the display. The z-axis projects perpendicular to the display surface, extending from the back side 312 through to the front side 310. This orientation framework provides a reference for understanding light propagation within the display structure. The viewing angle, measured relative to the z-axis, represents the observer's position deviation from a line normal to the display surface. As the viewing angle increases, moving away from the z-axis towards the x-y plane, the light paths through the display layers become more complex, influencing the effectiveness of the backlight leakage management system. For example, for angles ranging from 0 degrees (perpendicular to the display surface) to approximately 55 degrees, an anti- reflective coating applied to the first side of the first glass substrate may provide primary backlight leakage reduction. This coating may be optimized to minimize reflections in this angular range. However, as the viewing angle increases, moving away, the light paths through the display layers become more complex, those from approximately 60 degrees to 90 degrees relative to the display surface may need an effective backlight leakage management such as a light-absorbing element referred to as a black matrix as discussed further in this section.

[0151] Starting from the front side 310, the first layer illustrated is the front cover 302. This substrate may be typically made of a high-quality optical glass, chosen for its transparency and durability. The glass used for this substrate may be a borosilicate glass, aluminosilicate glass, or other specialized optical glass formulations. The front cover 302 may provide protection for the underlying display components, offers a smooth surface for touch interactions if required, and plays a role in the display's optical performance. The thickness of this front cover denoted as tr, is the parameter that influences the backlight leakage management capabilities of the display. The front cover 302 may also have a refractive index. The refractive index of the front cover 302 is denoted as m where the value may range from 1.45 to 1.55 for most optical glasses used in display applications. TheSP24-281 specific value of Vi is chosen to optimize light transmission while minimizing unwanted reflections.

[0152] Behind the front cover 302 is a layer of optical clear adhesive (OCA) 304. This OCA layer serves to bond the front cover to the subsequent layers while maintaining optical clarity. The OCA is typically a transparent, pressure-sensitive adhesive with a refractive index chosen to closely match that of the surrounding glass layers, minimizing internal reflections at the interfaces.

[0153] The next layer contains the pixels 305, which are the light-emitting elements of the display. Each pixel may contain one or more micro-LEDs or other suitable light-emitting components. The pixels 305 may be positioned such that the pixels may be designated as 305ai through 305axwhere “x” represents the total number of pixels shown. For example, if there are eight pixels, they would be labeled as 305ai, 305a2, 305as and so on, up to 305as. Each pixel 305 (305ai to 305ax) comprises both light-emitting areas and non-transmissive regions 330. The non-transmissive regions may include the micro-LED structures, associated electronics, and any opaque materials used in the pixel construction. These non-transmissive regions may be strategically placed block certain light paths. The pixels 305 are arranged in a regular pattern, with a distance between the centers of adjacent pixels defined as the pixel pitch, denoted by p. The pixels 305 may be fabricated on or transferred to the surface of a second substrate 306. This second substrate 306 provides structural support for the pixels and may incorporate the necessary electrical connections to drive the light-emitting elements. The second substrate 306 may be made of similar materials to the front cover 302, or it may be a specialized substrate optimized for the fabrication or transfer of micro-LED elements. The thickness of the second substrate 306 is denoted as tb.

[0154] Following the second substrate 306 is another layer of OCA 304. This layer serves a similar purpose to the first OCA layer, bonding the subsequent layers together while maintaining optical clarity.

[0155] The next layer is a layer 315 containing light-absorbing elements 307. The lightabsorbing elements also referred to as the “black matrix,” assists in managing backlight leakage and may be fabricated on the back surface of substrate 306 or the front surface of a back cover 308. The black matrix (e.g., light-absorbing elements 307) may be composed of a material with high light absorption properties across the visible spectrum. This could be a polymer with carbon black, a thin metal film, or a stack of dielectric materials designed to maximize light absorption. The black matrix (e.g., light-absorbing elements 307) are alignedSP24-281 with the center of a corresponding pixel 305 (305ai to 305ax) non-transmissive region 330 and may match the shape of that non-transmissive region 330. The size of the black matrix (e.g., light-absorbing elements 307) may be the same as or smaller than the non-transmissive region of the corresponding pixel. The width of the black matrix is denoted as Wbm, and the thickness as tum. These dimensions may be configured to provide maximum light absorption while minimizing impact on the overall transparency of the transparent display. A wider black matrix may provide better light absorption but may reduce the display's overall transparency and potentially impact its resolution. The thickness of the black matrix elements (tBm) also affects their light absorption capacity. Thicker black matrix elements generally absorb more light and block more light in a wider angle range but may introduce challenges in the manufacturing process and increase the overall thickness of the display. The placement of the black matrix layer 315 within the display stack may also influence its effectiveness. Positioning the black matrix layer 315 towards the back of the display allows the black matrix (e.g., light-absorbing elements 307) to absorb light that has already been reflected multiple times within the display structure. Alternative configurations might place the black matrix layer 315 closer to the pixels or even incorporate it into the pixel structure itself.

[0156] In some embodiments, each of the light-absorbing elements 307 referred to as the black matrix may have a surface area that is substantially equal to the surface area of the non- transmissive region 330 of a corresponding pixel 305 corresponding to a perpendicular direction of a viewing direction.

[0157] In some embodiments, each of the light-absorbing elements 307 referred to as the black matrix may have a surface area that may be less than a surface area of the non- transmissive region 330 of a corresponding pixel 305 corresponding to a perpendicular direction of a viewing direction.

[0158] In some embodiments, each of the light-absorbing elements 307 referred to as the black matrix may have a surface area that may be greater than a surface area of the non- transmissive region 330 of a corresponding pixel 305 corresponding to a perpendicular direction of a viewing direction.

[0159] As mentioned, within each pixel 305 (305ai to 305ax), there may be the non- transmissive region 330. This area includes the opaque components of the pixel structure, such as electrodes, transistors, or other control circuitry necessary for the operation of the light-emitting elements. The non-transmissive region 330 and their associated electronics may form a grid-like pattern of opaque areas across the display due to their uniform spacingSP24-281 and interconnections. While this inherent grid of electronics provides some light blocking functionality, additional light-blocking structures such as the black matrix may be incorporated to enhance backlight leakage control. When a pixel emits light, represented by ray 350, it travels through the various layers towards the viewer at the front side 310 of the display. As this light encounters the interface 322 between the front cover 302 and the surrounding medium (typically air), a portion of it is reflected back into the display structure due to the difference in refractive indices. This reflected light is represented by rays 351. The angles at which this light is reflected is denoted by 5i and <Oi associated with rays 350 and 351. The specific angles depend on the initial angle of the emitted light and the refractive indices of the materials involved. Depending on the angle of reflection and the ratio of the front cover thickness (tr) to the pixel pitch (p), these reflected rays 351 may intersect with the neighboring pixel’s non-transmissive region 330 or the black matrix (e.g., light-absorbing elements 307). If a reflected ray does not intersect with the non-transmissive region 330 of a neighboring pixel, a black matrix element (e.g., light-absorbing elements 307) may block and / or absorb the reflected light ray, preventing it from contributing to backlight leakage. This blocking effect is illustrated by ray 324, which represents an expected path of the light ray exiting the back of the display indicating that the light ray is blocked by the black matrix.

[0160] The effectiveness of this blocking may depend on several factors, including the tr / p ratio, the separation (tb) between pixels 305 and black matrix (e.g., light-absorbing elements 307), the dimensions of the black matrix elements (Wbm and tBm), and the refractive indices of the various layers (m, , ns, etc.). By configuring these parameters, it becomes possible to control the angles at which backlight leakage is most effectively suppressed. This geometric approach to backlight leakage management allows for the creation of minimums in the angular distribution of leakage light, minimizing unwanted light emission across a wide range of viewing angles.

[0161] The ratio of the front cover thickness (tr) to the pixel pitch (p) also determines the angles at which reflected light is most likely to intersect with non-transmissive regions 330 and / or black matrix (e.g., light-absorbing elements 307). A larger tf / p ratio generally results in reflected light intersecting with non-transmissive regions 330 and / or black matrix (e.g., light-absorbing elements 307) at smaller angles relative to the display normal. This can be beneficial for suppressing backlight leakage at near-normal viewing angles but may be less effective at extreme angles. Conversely, a smaller tr / p ratio allows for more effective blocking of light at larger angles, potentially improving the display's privacy characteristicsSP24-281 when viewed from the side. However, this may come at the cost of increased leakage at nearnormal angles. The optimal tr / p ratio may depend on the specific requirements of the display application, balancing factors such as viewing angle range, privacy needs, and overall display thickness.

[0162] The separation (tb) between pixels 305 and black matrix (e.g., light-absorbing elements 307) also determines the angles at which reflected light is most likely to intersect with black matrix 307. A larger tb generally results in reflected light intersecting with black matrix (e.g., light-absorbing elements 307) at smaller angles relative to the display normal. This can be beneficial for suppressing backlight leakage at near-normal viewing angles and in a narrower-angle range but may be less effective at extreme angles. Conversely, a smaller tb allows for more effective blocking of light at larger angles and in a wider-angle range, potentially improving the display's privacy characteristics when viewed from the side. The optimal tb ratio may depend on the specific requirements of the display application, balancing factors such as viewing angle range, privacy needs, and overall display thickness.

[0163] The pixel pitch (p) in display refers to the distance between the centers of adjacent pixels. This parameter influences the display's resolution and affects its backlight leakage characteristics. The pixel pitch contributes to the backlight leakage management system by affecting the paths of reflected light within the display structure. The pixel pitch relates to the display's resolution, a smaller pitch results in a higher pixel density. Pixel pitch interacts with backlight leakage in several ways. A decrease in pixel pitch reduces the spacing between light-emitting elements, potentially increasing the opportunities for reflected light to encounter non-transmissive regions and / or black matrix. However, this reduced spacing also means light travels a shorter distance before meeting another pixel and / or black matrix, which may affect the angles at which blocking occurs.

[0164] The positioning and alignment of the black matrix (e.g., light-absorbing elements 307) corresponds to the pixel pitch (p), ensuring that the black matrix (e.g., light-absorbing elements 307) cover the gaps between adjacent pixels. The black matrix pattern may correspond with the non-transmissive region 330 of a pixel 305, this alignment is configured such that light reflected from one pixel has a high probability of being absorbed by the black matrix before it can escape through a neighboring area. The width of the black matrix elements (Wbm) relates directly to the pixel 305. The thickness of the black matrix elements (tBm) also factors into their alignment and effectiveness. While increased thickness can improve light absorption and block more light in a wider-angle range, it may also introduceSP24-281 challenges in maintaining proper alignment with the pixel structure, particularly for displays with smaller pixel pitches. In some embodiments, this thickness may range from 0.5 micrometers to 0.5 millimeters. The specific thickness is selected based on factors such as the desired level of light absorption, overall display thickness constraints, and manufacturing considerations.

[0165] In some embodiments, the black matrix might be patterned directly onto the substrate adjacent to the pixels, ensuring alignment.

[0166] The alignment tolerance for the black matrix becomes more exacting as the pixel pitch decreases. Displays with smaller pixel pitches require more precise alignment to maintain the intended light-blocking function without impacting the display's visual performance.

[0167] The refractive index of each layer may also play a role in determining the path of light through the display. The refractive index of the front cover ( ) determines the angle at which light is refracted when entering or leaving the display. The difference between ni and the refractive index of the surrounding medium (typically air, with n ~ 1) determines the amount of reflection at the front surface. A larger difference leads to more reflection, potentially increasing backlight leakage. The refractive index of the OCA layers may also be matched with the surrounding materials to minimize internal reflections and to maintain its optical properties over the lifetime of the display, resisting degradation due to factors such as heat and UV exposure. The refractive indices of the subsequent layers (n2, ns, etc.) may be chosen to minimize internal reflections at the interfaces between layers. This often involves selecting materials with similar refractive indices or using index-matching optical clear adhesives.

[0168] The final layer in the display stack is the back cover 308. While some transparent display applications may not include a back cover 308, incorporating aback cover 308 may contribute to improved backlight leakage reduction. This plate provides additional structural support and protection for the display components. It may be made of similar materials to the front cover 302, or it could be a different material chosen for specific optical or mechanical properties. The back cover 308 serves not only as a protective layer but also as part of the optical system. In some embodiments, the back cover may incorporate additional optical features such as diffusers or reflectors to further control the light distribution within the display.SP24-281

[0169] In addition to managing backlight leakage, the structure described in FIG. 11A may also help to reduce other optical artifacts in transparent displays, such as ghost images and internal reflections. By controlling the paths of reflected light within the display, it's possible to minimize these unwanted effects and improve overall image quality.

[0170] In some embodiments, the effectiveness of this backlight leakage management approach can be further enhanced by combining it with other optical treatments. For instance, anti-reflective coatings may be applied to the front and back surfaces of the display. These anti-reflective coatings may be particularly effective at reducing reflections at near-normal incidence, complementing the geometric blocking approach which is often more effective at larger angles. In some embodiments, the anti -reflective coatings may be optimized differently from conventional AR coatings, taking into account the specific angular distribution of light within the display structure.

[0171] The light-absorbing elements 307 or the black matrix and the overall display structure are configured to manage backlight leakage across a wide range of viewing angles. The effectiveness of backlight leakage reduction varies depending on the angle of light propagation relative to the display surface normal.

[0172] In some embodiments, the black matrix elements may be fabricated using materials with anisotropic absorption properties. This may allow for greater absorption of light traveling at oblique angles while maintaining transparency for light traveling normal to the display surface.

[0173] In some embodiments, gradient-index materials may be incorporated in one or more of the display layers. For example, the front cover might use a material with a refractive index that gradually changes from front to back. This can provide additional control over light paths within the display, potentially allowing for even more effective backlight leakage management.

[0174] In some embodiments, the black matrix elements may be structured at the microscale or nanoscale to enhance their light-absorbing properties. This could involve the use of photonic crystals, metamaterials, or other engineered structures designed to maximize light absorption across a wide range of wavelengths and incident angles.

[0175] In some embodiments, this backlight leakage management approach may be extended to non-planar display geometries. For curved or flexible displays, the relationships between layer thicknesses, pixel pitch, and black matrix dimensions may be adjusted to account for the curvature of the display surface.SP24-281

[0176] In some embodiments, the display may incorporate additional layers or structures specifically designed to manage light at extreme viewing angles. This could include elements such as micro-louvers or specialized diffusive layers that become active only at large angles from the display normal.

[0177] The combination of these various elements and potential configurations demonstrates the flexibility and potential of this transparent display. By balancing and optimizing these components, the display can be tailored to meet the specific requirements of diverse applications, from consumer electronics to specialized industrial or medical uses, all while addressing the challenge of backlight leakage in transparent displays.

[0178] FIG. 1 IB illustrates an embodiment of the transparent display, building upon the structure shown in FIG. 11A. This configuration, shown as transparent display 400, incorporates additional layers with light-absorbing elements to enhance backlight leakage management.

[0179] The display 400 is bounded by a front side 410, facing the viewer, and a back side 412, opposite to the viewer. The layered structure of the display begins with the front cover 402 a component which may be made from high-quality optical glass, chosen for its transparency and durability. Behind the front cover 402 is a layer of optical clear adhesive (OCA) 404, which bonds the front cover to the subsequent layers while maintaining optical clarity. The next layer contains pixels 405, which are the light-emitting components of the display. The pixels 405 may be positioned such that the pixels may be designated as 405ai through 405axwhere “x” represents the total number of pixels shown. For example, if there are eight pixels, they would be labeled as 405ai, 405a2, 405as and so on, up to 405as. Each pixel 405 (405ai to 405ax) comprises both light-emitting areas and non-transmissive regions 430. The non-transmissive regions may include the micro-LED structures, associated electronics, and any opaque materials used in the pixel construction. These non-transmissive regions may strategically be used to the blocking of certain light paths. The pixels 405 are arranged in a regular pattern, with a distance between the centers of adjacent pixels defined as the pixel pitch, denoted by p. The pixels 405 may be typically fabricated on or transferred to the surface of a second substrate 406. This substrate provides structural support for the pixels and may incorporate the necessary electrical connections to drive the light-emitting elements. The second substrate 406 may be made of similar materials to the front cover 402, or it may be a specialized substrate optimized for the fabrication or transfer of micro-LED elements.SP24-281The thickness of this substrate is denoted as tb. Following the second substrate 406 is another layer of OCA 404, serving a similar purpose to the first OCA layer.

[0180] The transparent display 400 may also comprise a layer 415 containing lightabsorbing elements 407. The light- absorbing elements also referred to as the “black matrix,” assists in managing backlight leakage. The black matrix (e.g., light-absorbing elements 407) may be composed of a material with high light absorption properties across the visible spectrum. This could be a polymer with carbon black, a thin metal film, or a stack of dielectric materials designed to maximize light absorption. The black matrix (e.g., lightabsorbing elements 407)is aligned with the center of a corresponding pixel 405 (405ai to 405ax) non-transmissive region 430 and may match the shape of that non-transmissive region 430. The size of the black matrix (e.g., light-absorbing elements 407) may be the same as or smaller than the non-transmissive region of the corresponding pixel. The width of the black matrix (e.g., light-absorbing elements 407) is denoted as Wbm, and has thickness denoted as tBm. These dimensions may be configured to provide maximum light absorption while minimizing their impact on the overall transparency of the display. A wider black matrix may provide better light absorption but may reduce the display's overall transparency and potentially impact its resolution. The thickness of the black matrix elements (tBm) affects their light absorption capacity. Thicker elements generally absorb more light but may introduce challenges in the manufacturing process and increase the overall thickness of the display. The placement of the black matrix layer 415 within the display stack may also influence its effectiveness. Positioning the black matrix (e.g., light-absorbing elements 407) towards the back of the display allows the black matrix to absorb light that has already been reflected multiple times within the display structure. Alternative configurations might place the black matrix closer to the pixel layer or even incorporate it into the pixel structure itself.

[0181] In some embodiments, each of the light-absorbing elements 407 referred to as the black matrix may have a surface area that is substantially equal to the surface area of the non- transmissive region 430 of a corresponding pixel 405 corresponding to a perpendicular direction of a viewing direction.

[0182] In some embodiments, each of the light-absorbing elements 407 referred to as the black matrix may have a surface area that may be less than a surface area of the non- transmissive region 430 of a corresponding pixel 405 corresponding to a perpendicular direction of a viewing direction.SP24-281

[0183] In some embodiments, each of the light-absorbing elements 407 referred to as the black matrix may have a surface area that may be greater than a surface area of the non- transmissive region 430 of a corresponding pixel 405 corresponding to a perpendicular direction of a viewing direction.

[0184] The transparent display 400 may also comprise of multiple layers containing the black matrix (e.g., light-absorbing elements 407). Layer 417 is shown as the second layer that contains the black matrix 407. The black matrix 407 are positioned behind the black matrix of layer 415. The alignment of these elements corresponds to those in layer 415, creating a multi-layer light absorption structure. The spacing between layers 415 and 417 is denoted as tb2. This spacing can be adjusted to optimize the light absorption characteristics of the multilayer structure.

[0185] Layer 419 may be a third layer of light-absorbing elements, or referred as black matrix (e.g., light-absorbing elements 407), positioned behind layer 417. It follows the same alignment principle as the previous two layers, with the black matrix of layer 419 corresponding to the black matrix of those in layer 417, creating a multi-layer light absorption structure.

[0186] The presence of these multiple layers (415, 417, 419) allows for enhanced light absorption compared to a single-layer configuration. Light that may pass through gaps in one layer has additional opportunities to be absorbed by the subsequent layers. The alignment of the black matrix (e.g., light-absorbing elements 407) across all three layers (415, 417, 419) are aligned with the center of a corresponding pixel’s non-transmissive region 430. This arrangement allows the black matrix to absorb light that has been reflected from the front cover 402 and is traveling back through the display structure. The positioning of these elements in relation to the pixel structure enhances the display's capacity to intercept and absorb light that would otherwise contribute to backlight leakage. The multiple layers of black matrix elements provide additional opportunities for absorption, potentially increasing the effectiveness of backlight leakage reduction compared to a single-layer configuration.

[0187] The thicknesses of the layers (tb2, tbs) may be varied to optimize light absorption across different angles and wavelengths. This multi-layer approach provides additional design flexibility in managing backlight leakage.

[0188] As mentioned earlier, within each pixel 405 (405ai to 405ax), there is the non- transmissive region 430. This area includes the opaque components of the pixel structure, such as electrodes, transistors, or other control circuitry necessary for the operation of theSP24-281 light-emitting elements. The light paths within this display structure a generated by the lightemitting components of a pixel are presented by ray 450. As this light encounters the interface 420 and 422 between the front cover 402 and the surrounding medium (typically air), a portion of it is reflected back into the display structure due to the difference in refractive indices. This reflected light is represented by rays 451. The angles at which this light is reflected is denoted by 5i and coi associated with rays 450 and 451. The specific angles depend on the initial angle of the emitted light and the refractive indices of the materials involved. Depending on the angle of reflection and the ratio of the front cover thickness (tr) to the pixel pitch (p), these reflected rays 451 may intersect with neighboring pixels non-transmissive region 430 or the black matrix (e.g., light-absorbing elements 407) of any of the multiple layers. If a reflected ray does not intersect with the non-transmissive region 430 of a neighboring pixel, a black matrix element 407 of the multiple black matrix layers (415, 417, and 419) may block or absorb the reflected light ray, preventing it from contributing to backlight leakage. Light ray 424 represents an expected path of the light ray exiting the back of the transparent display that is blocked by the black matrix (e.g., lightabsorbing elements 407) and the multiple black matrix layers. This illustrates how light that might contribute to backlight leakage is absorbed by one or more of the black matrix layers.

[0189] The effectiveness of this blocking depends on several factors, including the ratio of the front cover thickness (tr) to the pixel pitch (p), the dimensions of the black matrix (Wbm and tBm in each layer), the separation (tbi) between pixels 405 and black matrix (e.g., lightabsorbing elements 407), the spacing between black matrix layers (tb2, ta), and the refractive indices of the various layers (m, , ns, etc.). The ratio of the front cover thickness (tr) to the pixel pitch (p) determines the angles at which reflected light is most likely to intersect with non-transmissive regions or the black matrix. A larger tf / p ratio generally results in reflected light intersecting with non-transmissive regions at smaller angles relative to the display normal. This may be beneficial for suppressing backlight leakage at near-normal viewing angles but may be less effective at extreme angles. Conversely, a smaller tf / p ratio allows for more effective blocking of light at larger angles, potentially improving the display's privacy characteristics when viewed from the side. However, this may come at the cost of increased leakage at near-normal angles. The optimal tf / p ratio may depend on the specific requirements of the display application, balancing factors such as viewing angle range, privacy needs, and overall display thickness.SP24-281

[0190] The refractive index of each layer may also play a role in determining the path of light through the display. The refractive index of the front cover ( ) determines the angle at which light is refracted when entering or leaving the display. The difference between ni and the refractive index of the surrounding medium (typically air, with n ~ 1) determines the amount of reflection at the front surface. A larger difference leads to more reflection, potentially increasing backlight leakage. The refractive index of the OCA layers may also be matched with the surrounding materials to minimize internal reflections and to maintain its optical properties over the lifetime of the display, resisting degradation due to factors such as heat and UV exposure. The refractive indices of the subsequent layers (n2, ns, etc.) may be chosen to minimize internal reflections at the interfaces between layers. This often involves selecting materials with similar refractive indices or using index-matching optical clear adhesives.

[0191] The multi-layer black matrix structure provides comprehensive coverage of potential light leakage paths. Light that might escape absorption in one layer has a high probability of being absorbed in subsequent layers. This configuration allows for optimization of backlight leakage suppression across a wide range of viewing angles. The multiple layers may be configured to effectively absorb light traveling at various angles through the display structure. The black matrix (e.g., light-absorbing elements 407) in the different layers could potentially be optimized for different wavelengths of light. This could allow for more uniform suppression of backlight leakage across the visible spectrum.

[0192] While FIG. 1 IB shows three layers (415, 417, 419) of black matrix, other embodiments may incorporate more or fewer layers. The number of layers may be adjusted based on factors such as the desired level of backlight leakage suppression, manufacturing considerations, and overall display thickness constraints.

[0193] The multi-layer approach offers potential benefits in terms of manufacturing tolerances. Small misalignments or imperfections in one layer may be compensated for by subsequent layers, potentially improving the overall performance of the backlight leakage management system. The optical properties of the materials used in the multi-layer black matrix structure, including their refractive indices and absorption coefficients may be selected to achieve optimal performance across the visible spectrum and at various viewing angles. The multi-layer black matrix structure presented in FIG. 1 IB represents an approach to backlight leakage management in transparent displays that builds upon the single-layer configuration. By providing multiple opportunities for light absorption, this configurationSP24-281 may enhance the suppression of unwanted light emission across a wide range of viewing angles.

[0194] FIG. 11C illustrates another embodiment of the transparent display, building upon the structure shown in FIG. 1 IB. This embodiment illustrates a transparent display 500 incorporating the multilayer black matrix structure with a pitch configuration.

[0195] As with the previous embodiments, the display 500 is bounded by a front side 510, facing the viewer, and a back side 512, opposite to the viewer. The layered structure of the display begins with the front cover 502, followed by a layer of optical clear adhesive (OCA) 504. After this is a layer contain pixels 505 which contain the light-emitting components of the display, typically micro-LEDs or other suitable light-emitting elements. The pixels 505 may be positioned such that the pixels may be designated as 505ai through 505axwhere “x” represents the total number of pixels shown. For example, if there are eight pixels, they would be labeled as 505ai, 505a2, 505as and so on, up to 505as. Each pixel 505 (505ai to 505ax) comprises both light-emitting areas and non-transmissive regions 530. The non-transmissive regions may include the micro-LED structures, associated electronics, and any opaque materials used in the pixel construction. These non-transmissive regions may strategically be used in the blocking of certain light paths. The pixels 505 are arranged in a regular pattern, with a distance between the centers of adjacent pixels defined as the pixel pitch, denoted by p. The pixels 505 may be typically fabricated on or transferred to the surface of a second substrate 506. This substrate provides structural support for the pixels and may incorporate the necessary electrical connections to drive the light-emitting elements. The second substrate 506 may be made of similar materials to the front cover 502, or it may be a specialized substrate optimized for the fabrication or transfer of micro-LED elements. The thickness of this substrate is denoted as tbi. Following the second substrate 506 is another layer of OCA 504, serving to bond subsequent layers.

[0196] This embodiment illustrates a configuration of the multilayer black matrix structure, represented by layers 515, 517, and 519. Each of these layers contains a black matrix, which comprise light-absorbing elements 507 to absorb light that could contribute to backlight leakage. In this embodiment, the pitch of the black matrix (e.g., light-absorbing elements 507) is configured to be two or more times the pixel pitch of the display. This means that the distance between the centers of adjacent black matrix elements is larger than the distance between pixels. The increased pitch of the black matrix (e.g., light-absorbing elements 507) may affect how the display manages backlight leakage. With a larger spacingSP24-281 between each black matrix (e.g., light-absorbing elements 507), there are fewer absorption sites, but each site can potentially cover a larger area. This creates a pattern where a black matrix may align with every second, third, or fourth pixel, depending on the specific multiple chosen. This configuration may particularly be effective at absorbing light that has been reflected at high angles from the front cover 502. These high-angle reflections are often associated with instances of backlight leakage that are challenging to manage.

[0197] The multilayer structure of the black matrix, combined with the increased pitch, creates a pattern of absorption sites that can intercept light traveling through the display at various angles. Layer 515 is the first layer containing the black matrix (e.g., light-absorbing elements 507). The black matrix (e.g., light-absorbing elements 507) are aligned to with the center of a corresponding non-transmissive region 530. This arrangement allows the black matrix (e.g., light-absorbing elements 507) to absorb light that has been reflected from the front cover 502 and is traveling back through the display structure.

[0198] Layer 517, the second layer comprising the black matrix (e.g., light-absorbing elements 507), is positioned behind layer 515. The black matrix (e.g., light-absorbing elements 507) of the second layer 517 may be aligned to correspond with every second non- transmissive region 530 of pixel 505, depending on the exact multiple of the pixel pitch used for the black matrix pitch.

[0199] Layer 519, the third layer comprising a black matrix (e.g., light-absorbing elements 507), is positioned behind layer 517. The black matrix (e.g., light-absorbing elements 507) of layer 519 may be aligned to correspond with every third non-transmissive 530 area of pixel 505, depending on the exact multiple of the pixel pitch used for the black matrix pitch.

[0200] When a pixel emits light, represented by ray 550, it travels through the various layers towards the viewer at the front side 510 of the display. As this light encounters the interface 520 and 522 between the front cover 502 and the surrounding medium (typically air), a portion of it is reflected back into the display structure due to the difference in refractive indices. This reflected light is represented by rays 551. The angles at which this light is reflected is denoted by 5i and <Oi associated with rays 550 and 551. The specific angles depend on the initial angle of the emitted light and the refractive indices of the materials involved. Depending on the angle of reflection and the ratio of the front cover thickness (tr) to the pixel pitch (p), these reflected rays 551 may intersect with neighboring pixel’s non-transmissive region 530 or the black matrix (e.g., light-absorbing elements 507)SP24-281 of the multilayer black matrix structure. If a reflected ray does not intersect with the non- transmissive region 330 of a neighboring pixel, a black matrix (e.g., light-absorbing elements 507) may block or absorb the reflected light ray. If light escapes absorption in one layer, there is a high probability the light of being absorbed in subsequent layers, preventing it from contributing to backlight leakage. With the increased pitch of the black matrix (e.g., lightabsorbing elements 507), this blocking may occur at different points compared to a structure with a black matrix pitch matching the pixel pitch.

[0201] As mentioned in the previous sections, the effectiveness of the configuration may depend on several factors, including the ratio of the front cover thickness (tr) to the pixel pitch (p), the dimensions of the black matrix elements (Wbm and tum in each layer), the spacing between black matrix layers (tb2, tbs), and the refractive indices of the various layers (ni, n2, ns, etc.). The ratio of the front cover thickness (tr) to the pixel pitch (p) determines the angles at which reflected light is most likely to intersect with non-transmissive regions or black matrix elements. A larger tf / p ratio generally results in reflected light intersecting with non-transmissive regions at smaller angles relative to the display normal. This may be beneficial for suppressing backlight leakage at near-normal viewing angles but may be less effective at extreme angles. Conversely, a smaller tf / p ratio allows for more effective blocking of light at larger angles, potentially improving the display's privacy characteristics when viewed from the side. However, this may come at the cost of increased leakage at nearnormal angles. The optimal tf / p ratio may depend on the specific requirements of the display application, balancing factors such as viewing angle range, privacy needs, and overall display thickness.

[0202] The increased pitch of the black matrix (e.g., light-absorbing elements 507) may allow for larger dimensions of the black matrix, potentially increasing the absorption capability of each black matrix (e.g., light-absorbing elements 507). This could be beneficial for absorbing high-angle reflections that might otherwise escape a more closely spaced black matrix structure. However, the larger spacing between each black matrix also means that there are more opportunities for light to pass through the structure without encountering an absorption site.

[0203] In some embodiments, this structure of the black matrix elements might explore different multiples of the pixel pitch for the black matrix pitch. For example, a structure where the black matrix pitch is three or four times the pixel pitch could be considered.SP24-281

[0204] The multilayer nature of the black matrix structure in this embodiment provides multiple opportunities for light absorption, potentially compensating for the increased spacing between elements in each individual layer. The multilayer black matrix structure with increased pitch represents an approach to backlight leakage management that explores a different balance between absorption site density and coverage area. This configuration may address high-angle backlight leakage while potentially offering manufacturing advantages.

[0205] Moving on, FIG. 12 illustrates a graph depicting the normalized intensity of backlight leakage as a function of viewing angle for various configurations of a transparent display. The graph presents data for four cases, each representing a different combination of anti-reflective (AR) coating and black matrix (BM) layer implementations.

[0206] Table 2 presents the modeling cases and their relevant parameters:TABLE 2

[0207] Table 2 details the relative paraments as follows: Front cover thickness, tr (mm): This is the thickness of the display's front cover; Front OCA layer thickness (mm): This refers to the thickness of the optical clear adhesive layer on the front of the display; Pixel pitch, p (mm): This is the distance between the centers of adjacent pixels in the display; Ratio, tr / p: This represents the ratio of front cover thickness to pixel pitch, a parameter that influences backlight leakage behavior; Front surface of front cover: This indicates whether an anti-reflective (AR) coating is applied to the front surface of the display; Substrate thickness, tb (mm): This is the thickness of the substrate on which the pixels are fabricated; Back OCA layer thickness (pm): This refers to the thickness of the optical clear adhesive layer on the back of the display; Black Matrix (BM) parameters: These include the width (WBM), length (WBM), and thickness (IBM) of the black matrix elements, as well as their surface reflectance and transmittance percentages.

[0208] The graph in FIG. 12 presents data for four cases from Table 2: Bl, B3, DI, and D2. These cases represent different combinations of AR coating and black matrix implementations.

[0209] The horizontal axis of the graph represents the viewing angle, measured in degrees, relative to the display back surface. The range extends from 0 to 90 degrees, where 0 degreesSP24-281 corresponds to a direction perpendicular to the display surface, and 90 degrees represents a direction parallel to the display surface. The vertical axis shows the normalized intensity of backlight leakage, with values ranging from 0 to 1.2. This normalization allows for direct comparison between different configurations, with higher values indicating greater backlight leakage.

[0210] To quantify the effectiveness of each configuration, Table 3 summarizes the results:TABLE 3

[0211] Table 3 presents: Case number (#) corresponding to the configurations in Table 2; Maximum normalized intensity of backlight leakage: The peak intensity of backlight leakage for each case; and Reduction of maximum normalized intensity compared with case Bl (%): The percentage reduction in peak backlight leakage intensity compared to the baseline case (Bl).

[0212] With these parameters and results in mind, the graph in FIG. 12 can be interpreted as follows: The graph contains four curves, each corresponding to a case as detailed in Table 2. These cases are Case B 1 : This configuration has neither AR coating nor a black matrix layer. Case Bl serves as a baseline for comparison, represented by the red curve in the graph. Case B3: This configuration incorporates AR coating 2 but no black matrix layer. Case DI: This configuration includes both AR coating 2 and an 8 pm thick black matrix layer. Case D2: This configuration features AR coating 2 and a 100 pm thick black matrix layer.

[0213] The curves demonstrate how the different configurations affect the intensity of backlight leakage across various viewing angles. Case Bl, without any light management features, shows the highest overall intensity of backlight leakage. Case B3, with AR coating 2, shows a reduction in backlight leakage intensity compared to Case B 1, particularly at lower viewing angles. Cases DI and D2, which combine AR coating 2 with black matrix layers of different thicknesses, demonstrate further reductions in backlight leakage intensity across all viewing angles. Table 3 summarizes the maximum normalized intensities of backlight leakage for each case and quantifies the reduction in maximum normalized intensity compared to the baseline Case B 1.

[0214] The addition of AR coating 2 (Case B3) reduces the maximum normalized intensity of backlight leakage by 50.54% compared to the baseline case. The introduction ofSP24-281 an 8 pm thick black matrix layer in addition to AR coating 2 (Case DI) further improves the reduction to 66.67% compared to the baseline. The use of a 100 pm thick black matrix layer with AR coating 2 (Case D2) provides the most reduction, decreasing the maximum normalized intensity by 68.82% compared to the baseline.

[0215] These results demonstrate that while AR coating alone provides reduction in backlight leakage, the addition of a black matrix layer may further enhance this effect. The thickness of the black matrix layer appears to have an impact on its effectiveness, with the thicker 100 pm layer providing slightly better performance than the 8 pm layer. The graph also reveals that the different configurations have varying effects on backlight leakage at different viewing angles. The AR coating appears particularly effective at reducing leakage at lower angles, while the black matrix layers provide additional suppression across the entire range of viewing angles.

[0216] This data suggests that combining AR coating with a black matrix layer in a transparent display may effectively reduce backlight leakage across all viewing angles, potentially improving both image quality and privacy characteristics of the display.

[0217] Moving on, FIG. 13, illustrates a cross-sectional view of a transparent display 700, incorporating a wire mesh structure for managing backlight leakage. This embodiment builds upon the concepts introduced in FIGs. 11A-11C, replacing the black matrix elements with a wire mesh.

[0218] As introduced in the previous sections, The display 700 is bounded by a front side 710, facing the viewer, and a back side 712, opposite to the viewer. The layered structure of the display begins with the front cover 702, a substrate composed of a transparent material with a refractive index m, which may be made from high-quality optical glass, chosen for its transparency and durability. Behind the front cover 702 is a layer of optical clear adhesive (OCA) 704, which bonds the front cover to the subsequent layers while maintaining optical clarity. The next layer contains the pixels 705. The pixels 705 may be positioned such that the pixels may be designated as 705ai through 705axwhere “x” represents the total number of pixels shown. For example, if there are eight pixels, they would be labeled as 705ai, 705a2, 705as and so on, up to 705as. Each pixel 705 (705ai to 705ax) comprises both light-emitting areas and non-transmissive regions 730. The non-transmissive regions may include microLED structures, associated electronics, and any opaque materials used in the pixel construction. These non-transmissive regions 730 may strategically be used in the blocking of certain light paths. The pixels 705 are arranged in a regular pattern, with a distance betweenSP24-281 the centers of adjacent pixels defined as the pixel pitch, denoted by p. The pixels 705 may be typically fabricated on or transferred to the surface of a second substrate 706. The second substrate 706 may be made of similar materials to the front cover 702, or it may be a specialized substrate optimized for the fabrication or transfer of micro-LED elements. This substrate provides structural support for the pixels and may incorporate necessary electrical connections, where substrate 706 may have a thickness tb. Substrate 706 may also have a different refractive index, denoted as n2. Following the second substrate 706 is another layer of OCA 704, serving a similar purpose to the first OCA layer.

[0219] The next layer is layer 715 comprises a network of thin, interconnected wires. These wires may be arranged in a grid pattern to create a wire mesh structure, where a series of openings are found throughout the structure. The wire mesh 707 represent the crosssections of the wires where they intersect the plane of the diagram, where the x-axis extends horizontally across the width of the display 700, The y-axis extends vertically along the height of the display 700, and the z-axis extends from the front side 710 to the back side 712 of the display 700. The plane depicted in FIG. 13 is parallel to the x-z plane of the display. In this view, the wire mesh 707 extends along the y-axis, perpendicular to the plane of the diagram. In a complete three-dimensional structure of the display, the wire mesh includes wires extending along the x-axis, and wires extending along the y-axis to create a mesh pattern where the spacing between adjacent wires matches the pixel pitch. This grid-like arrangement creates an opening formed by the intersecting wires which corresponds to a pixel location (705ai to 705ax). The wire mesh forms a network of wires that can intercept light traveling at various angles within the display structure. The positioning of the wire elements relative to other components of the display, such as the pixels 705 and the front cover 702, contributes to the management of backlight leakage.

[0220] In some embodiments, the wire mesh structure may be a woven wire mesh, where wires are interlaced in an over-under pattern. This weaving creates a grid-like structure with uniform openings between the wires. The size of these openings can be adjusted by altering the weave pattern and wire spacing.

[0221] In some embodiments, the wire mesh structure may be a welded wire mesh where the wires are arranged in a grid pattern and welded at their intersection points. This method provides stability to the structure and ensures consistent spacing between the wires.SP24-281

[0222] In some embodiments, the wire mesh structure may be formed by slitting and stretching a sheet of metal, resulting in a pattern of diamond-shaped openings. This configuration can offer a balance between structural integrity and light-blocking capabilities.

[0223] In some embodiments, the wire mesh structure may be formed using the black matrix (e.g., light-absorbing element) described in previous sections, or other materials capable of blocking or absorbing light.

[0224] In some embodiments, an extruded columnar structure, such as a square or honeycomb pattern, can be used in place of a wire mesh structure, which may offer greater thicknesses. This configuration can offer a balance between structural integrity and lightblocking capabilities.

[0225] The wire mesh 707 may be configured to control the path of light within the display structure. This may be achieved by physically obstructing light rays that would otherwise contribute to backlight leakage. When a pixel emits light, represented by ray 750, it travels through the various layers towards the viewer at the front side 710 of the display. As this light encounters the interface 720 and 722 between the front cover 702 and the surrounding medium (typically air), a portion of it is reflected back into the display structure due to the difference in refractive indices. This reflected light is represented by rays 751. The angles at which this light is reflected is denoted by 8i and co; associated with rays 750 and 751. The specific angles depend on the initial angle of the emitted light and the refractive indices of the materials involved. Depending on the angle of reflection and the ratio of the front cover thickness (tr) to the pixel pitch (p), these reflected rays 751 may intersect with neighboring pixel’s non-transmissive region 730 or the wire mesh 707. The wire mesh structure is configured to intercept these reflected rays, particularly those traveling at high angles relative to the display normal. Ray 724 represents an expected light path that is blocked by the wire mesh 707. This demonstrates how the wire mesh structure may prevent light from exiting the back of the display at certain angles. The effectiveness of the wire mesh in blocking light depends on several factors, the angle at which light is traveling (represented by angles epi and co;), the ratio of front cover thickness to pixel pitch (tf / p), and the dimensions and spacing of the wires in the wire mesh structure.

[0226] When light rays 751 encounter the wire mesh 707, several interactions may occur:- Reflection: If the wire material is reflective, incoming light may be redirected.This may potentially guide light back towards the front of the display, enhancing brightness.SP24-281- Absorption: If the wire material has light-absorbing properties, the wire may absorb the intercepted light, effectively removing light from the optical system.Scattering: Depending on the surface properties of the wires, light may be scattered in various directions upon contact.

[0227] The wire mesh’s ability to block light may be determined by its physical structure and placement within the display. The wires of the wire mesh may create obstruction zones that prevent light from traveling along certain paths, particularly at high angles relative to a viewing direction that is perpendicular to the surface of the display.

[0228] The effectiveness of the wire mesh in managing backlight leakage depends on several parameters. Similar to the black matrix discussed in previous sections, these parameters may rely on Twm, or the thickness of the wire mesh, which may influence the depth of the obstruction zone created by each wire. A greater thickness may block light over a wider range of angles but may impact the overall transparency of the display. Wwm, the width of the wire, may affect both the blocking effectiveness and the transparency of the mesh. Wider wires create larger obstruction zones but reduce the open area of the mesh. The spacing between each wire, which is related to the pixel pitch p, may determine the density of the wire mesh. Closer spacing provides more frequent light blocking, but this must be balanced against the transparency requirements. The placement of the wire mesh layer 715 within the display stack is another consideration. In this configuration, it is positioned behind the pixels 705, allowing it to intercept light that has already been reflected from the front cover interface, however alternative arrangements may be explored such as placing it closer to the pixel.

[0229] The wire mesh structure could potentially be combined with other light management approaches, such as anti-reflective coatings on the front cover surface, to further enhance backlight leakage control, or to add additional layers of wire mesh to further block light that may not have been block by the previous wire mesh layer. By modifying the mesh dimensions and spacing, specific angles for light blocking can be targeted while maintaining transparency at other angles. This allows for fine-tuning of the display's optical properties to meet specific requirements.

[0230] The material choice for the wire mesh may be of metals with high reflectivity, such as aluminum or silver, could be used to maximize light redirection. Alternatively, darker materials could be used if light absorption is preferred over reflection. The wire meshSP24-281 structure could be fabricated using various techniques, such as photolithography, electroplating, or advanced printing methods. The choice of fabrication method would depend on the desired mesh dimensions and material.

[0231] The wire mesh structure allows for adjustment of the display's optical properties. By modifying the mesh dimensions and spacing, specific angles for light blocking may be targeted while maintaining transparency at other angles.

[0232] Methods of making transparent displays with backlight leakage control are also contemplated. A flow chart illustrating an example method 900 for making a transparent display with backlight leakage control is provided in FIG. 14. At operation 910, a first glass substrate with a first side and a second side is positioned. The first side of the first glass substrate faces the viewer / user, while the second sides face the interior of the display. At operation 920, a second glass substrate comprising a first side and second side is positioned.

[0233] At operation 930, a layer comprising pixel emitting structures is positioned between the second side of the first glass substrate and the first side of the second glass substrate. The pixel emitting structures may comprise micro-LEDs, OLEDs, or other suitable light-emitting elements.

[0234] At operation 940, a layer comprising light-absorbing elements is positioned on the second side of the second glass substrate. The light-absorbing elements are configured to intercept and absorb light that might otherwise contribute backlight leakage.

[0235] At operation 950, the light-absorbing elements are aligned with a corresponding pixel emitting structure. This alignment is configured to position the light-absorbing elements to effectively capture light from pixel emitting structure to maximize reducing backlight leakage.

[0236] At operation 960, a thickness of the first glass substrate is selected, where the selection is based on a horizontal spacing between adjacent pixel emitting structures. The thickness of the first glass substrate may influence the path of light within the display and may affect the angles at which light may escape or be redirected.

[0237] At operation 970, an anti -reflective (AR) coating is applied to the first side of the first glass substrate to reduce reflection at the interface between the display and the surrounding environment to further contribute to the management of light within the transparent display.

[0238] In other embodiments, method 900 may be modified. For example, certain operations may be omitted from the methods and / or additional operations may be added toSP24-281 the methods. For example, where an AR coating is being applied, operations 970 may be omitted. Additionally, the operations provided in the methods may generally be performed in any order and may be performed simultaneously with each other in some instances.CONCLUSION

[0239] Many modifications and other embodiments set forth herein will come to mind to one skilled in the art to which these embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the embodiments are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the invention. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and / or functions, it should be appreciated that different combinations of elements and / or functions may be provided by alternative embodiments without departing from the scope of the invention. In this regard, for example, different combinations of elements and / or functions than those explicitly described above are also contemplated within the scope of the invention. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

SP24-281THAT WHICH IS CLAIMED:1 . A transparent display defining a front and a back, the transparent display comprising: a first glass substrate comprising a first side and a second side; a second glass substrate comprising a first side and a second side; a first layer between the second side of the first glass substrate and the first side of the second glass substrate, wherein the first layer comprises a plurality of pixel emitting structures, each of the plurality of pixel emitting structures comprising one or more light-emitting components; and a second layer positioned on the second side of the second glass substrate, wherein the second layer comprises a plurality of light-absorbing elements, each of the plurality of light-absorbing elements being aligned from the front to the back of the transparent display with a corresponding pixel emitting structure in the first layer, the light-absorbing elements being configured to absorb light reflected from the first glass substrate to reduce an amount of light visible from the back of the transparent display.

2. The transparent display of claim 1, wherein the first glass substrate comprises an anti- reflective coating on the first side of the first glass substrate.

3. The transparent display of any of claims 1-2, further comprising: a third glass substrate comprising a first side and a second side, wherein the third glass substrate is positioned adjacent the second layer on the second side of the second glass substrate; and a third layer comprising a plurality of light-absorbing elements, wherein the third layer is positioned on the second side of the third glass substrate.

4. The transparent display of claim 3, wherein the third glass substrate is configured as a back cover.

5. The transparent display of any of claims 1-2, wherein each pixel emitting structure of the plurality of pixel emitting structures comprises a non-transmissive region, the non-SP24-281 transmissive region including the one or more light-emitting components and an area surrounding the one or more light-emitting components.

6. The transparent display of claim 5, wherein a surface area of each of the plurality of light-absorbing elements is substantially equal to a surface area of the non-transmissive region of the corresponding pixel emitting structure, the surface area being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display.

7. The transparent display of claim 5, wherein a surface area of each of the plurality of light-absorbing elements is less than a surface area of the non-transmissive region of the corresponding pixel emitting structure, the surface area being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display.

8. The transparent display of claim 5, wherein a surface area of each of the plurality of light-absorbing elements is greater than a surface area of the non-transmissive region of the corresponding pixel emitting structure, the surface area being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display.

9. The transparent display of any of claims 1-8, wherein the one or more light-emitting components comprise micro-LEDs.

10. The transparent display of any of claims 1-8, wherein the one or more light-emitting components comprise OLEDs.11 . The transparent display of any of claims 1-10, wherein a thickness of the first glass substrate is selected relative to a horizontal spacing of the plurality of pixel emitting structures relative to each other, the horizontal spacing being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display, wherein the thickness is configured to cause light emitted from a first pixel emitting structure at a first range of reflection angles off the first glass substrate to be reduced by a non-transmissive region of one or more pixel emitting structures of the plurality of pixel emitting structures.SP24-28112. The transparent display of claim 11, wherein the first range of reflection angles includes angles extending from 55 degrees to 90 degrees relative to a viewing direction of the transparent display.

13. The transparent display of any of claims 11-12, wherein a thickness of the second glass substrate is selected to position the plurality of light-absorbing elements to absorb light at a second range of angles, the second range of angles being from approximately 1 degrees to 90 degrees relative a viewing direction of the transparent display, wherein the positioning of the plurality of light-absorbing elements is determined relative to the horizontal spacing of the plurality of pixel emitting structures relative to each other.

14. The transparent display of any of claims 11-13, wherein the first glass substrate comprises an anti-reflective coating on the first side of the first glass substrate, the anti- reflective coating on the first side of the first glass substrate being configured to reduce reflection of light at a third range of reflection angles, wherein the third range of reflection angles is from 0 degrees to approximately 70 degrees relative to the viewing direction of the transparent display.

15. The transparent display of any of claims 1-14, wherein the second layer has a thickness ranging from 0.5 micrometers to 0.5 millimeters.

16. The transparent display of claim 1, wherein the light-absorbing elements comprise a wire mesh structure that comprises a plurality of interconnected wires arranged in a grid pattern, wherein intersections of the grid pattern align from the front to the back of the transparent display with the corresponding pixel emitting structure.

17. A transparent display defining a front and back, the transparent display comprising: a first glass substrate comprising a first side and a second side; a second glass substrate comprising a first side and a second side; and a first layer between the second side of the first glass substrate and the first side of the second glass substrate, wherein the first layer comprises a plurality of pixel emitting structures, each pixel emitting structure of the plurality of pixel emitting structures comprising one or more light-emitting components and a non-SP24-281 transmissive region, the non-transmissive region including the one or more lightemitting components and an area surrounding the one or more light-emitting components, the plurality of pixel emitting structures being arranged with a horizontal spacing between adjacent pixel emitting structures, the horizontal spacing being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display; and wherein a thickness of the first glass substrate and the horizontal spacing between adjacent pixel emitting structures are each configured such that a portion of light emitted from the one or more light-emitting components of a first pixel emitting structure that reflects off the first glass substrate is blocked by the non- transmissive region of an adjacent second pixel emitting structure, reducing an amount of light leakage viewable from the back of the transparent display.

18. The transparent display of Claim 17, wherein the reduction in the amount of light leakage viewable from the back of the transparent display occurs at a function of a view angle, 0; wherein the function of view angle is determined by: 0; =wherein tf is the thickness of the first glass substrate, wherein p is the horizontal spacing between adjacent pixel emitting structures, wherein no is a refractive index the surrounding medium, and wherein ni is the refractive index of the first glass substrate.

19. The transparent display of claim 17, wherein the thickness of the first glass substrate and the horizontal spacing between adjacent pixel emitting structures are related by a ratio tf / p.

20. The transparent display of claim 19, wherein the ratio tf / p of the thickness of the first glass substrate to the horizontal spacing between adjacent pixel emitting structures is between 1.425 and 7.0.

21. The transparent display of claim 17, wherein the one or more light-emitting components comprise micro-LEDs.SP24-28122. The transparent display of any of claims 17-20, further comprising an anti -reflective coating on the first side of the first glass substrate, the anti-reflective coating being configured to reduce reflection of light at angles from 0 degrees to approximately 70 degrees relative to a viewing direction of the transparent display, and wherein the plurality of pixel emitting structures are configured to reduce light at angles from approximately 55 degrees to 90 degrees relative to the viewing direction of the transparent display.

23. A transparent display defining a front and a back, the transparent display comprising: a first glass substrate comprising a first side and a second side; a second glass substrate comprising a first side and a second side; a first layer between the second side of the first glass substrate and the first side of the second glass substrate, wherein the first layer comprises a plurality of pixel emitting structures, each pixel emitting structure of the plurality of pixel emitting structures comprising one or more lightemitting components and a non-transmissive region, the non- transmissive region including the one or more light-emitting components and an area surrounding the one or more light-emitting components, the plurality of pixel emitting structures being arranged with a horizontal spacing between adjacent pixel emitting structures, the horizontal spacing being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display; and a second layer positioned on the second side of the second glass substrate, wherein the second layer comprises a plurality of light-absorbing elements, each of the plurality of light-absorbing elements being aligned from the front to the back of the transparent display with a corresponding pixel emitting structure of the plurality of pixel emitting structures in the first layer, wherein the plurality of light-absorbing elements are configured to absorb light reflected from the first glass substrate; and wherein a thickness of the first glass substrate and the horizontal spacing between adjacent pixel emitting structures are configured such that a portion of light emitted from the one or more light-emittingSP24-281 components of a first pixel emitting structure that is reflected off the first glass substrate is blocked by the non-transmissive region of an adjacent second pixel emitting structure; wherein the second layer is further configured to absorb reflected light that passes around the non-transmissive region of the plurality of pixel emitting structures to further reduce an amount of light visible from the back of the transparent display.

24. The transparent display of claim 23, wherein the plurality of light-absorbing elements are aligned with the non-transmissive regions of the plurality of pixel emitting structures.

25. The transparent display of claim 23, wherein the thickness of the first glass substrate is configured to cause light emitted from the first pixel emitting structure at a first range of reflection angles to be reduced by the non-transmissive region of the adjacent second pixel emitting structure, the first range of reflection angles including angles extending from 55 degrees to 90 degrees relative to the back of the transparent display.

26. The transparent display of claim 25, wherein a thickness of the second glass substrate is selected to position the plurality of light-absorbing elements to absorb light at a second range angle, the second range of angles being from approximately 1 degrees to 90 degrees relative to the back of the transparent display wherein the positioning of the plurality of lightabsorbing elements is determined relative to the horizontal spacing of the plurality of pixel emitting structures.

27. The transparent display of any of claims 23-26, wherein the first glass substrate comprises an anti-reflective coating on the first side of the first glass substrate, the anti- reflective coating on the first side of the first glass substrate being configured to reduce reflection of light at a third range of reflection angles, wherein the third range of reflection angles is from 0 degrees to approximately 70 degrees relative to the back of the transparent display.

28. A method of creating a transparent display, wherein the transparent display defines a front and back, the method comprising:SP24-281 providing a first glass substrate comprising a first side and a second side; providing a second glass substrate comprising a first side and as second side; positioning a first layer between the second side of the first glass substrate and the first side of the second glass substrate, wherein the first layer comprises a plurality of pixel emitting structures, each pixel emitting structure of the plurality of pixel emitting structures comprising one or more light-emitting components and a non-transmissive region, the non-transmissive region including the one or more light-emitting components and an area surrounding the one or more light-emitting components, the plurality of pixel emitting structures being arranged with a horizontal spacing between adjacent pixel emitting structures, the horizontal spacing being in a plane corresponding to a perpendicular direction of a viewing direction of the transparent display; positioning a second layer on the second side of the second glass substrate, wherein the second layer comprises a plurality of light-absorbing elements, aligning the plurality of light-absorbing elements from the front to the back of the transparent display with a corresponding pixel emitting structure of the plurality of pixel emitting structure in the first layer; and selecting a thickness of the first glass substrate based on the horizontal spacing between the adjacent pixel emitting structures of the plurality of pixel emitting structures, such that a portion of the light emitted from the one or more light-emitting components of a first pixel emitting structure that is reflected off the first glass substrate is blocked by the non-transmissive region of an adjacent second pixel emitting structure, wherein the second layer is further configured to absorb reflected light that passes around the non-transmissive region of the plurality of pixel emitting structures to further reduce an amount of light visible from the back of the transparent display.

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