Description:FORMULATION OF OPTICALLY TRANSPARENT BONDING MEDIUM FOR RUGGEDIZATION OF LCD

BACKGROUND

TECHNICAL FIELD

[0001] The present disclosure relates to optically clear bonding materials for electronic displays and, more particularly, to a ratio-controlled optically transparent bonding medium formulation and a method for manufacturing ruggedized Liquid Crystal Display (LCD) assemblies.

DESCRIPTION OF THE RELATED ART

[0002] Liquid Crystal Displays (LCDs) are extensively employed in a wide range of electronic systems owing to their low power consumption, compact form factor, and cost-effectiveness. In many applications, particularly those involving defense platforms, aerospace systems, transportation infrastructure, and industrial equipment, Commercial Off-The-Shelf (COTS) LCDs are increasingly adopted to reduce development time and manufacturing cost. However, such COTS LCDs are primarily designed for operation under controlled and benign environmental conditions.
[0003] When deployed in rugged operating environments, LCD assemblies are routinely exposed to mechanical shock, continuous vibration, thermal cycling, humidity, and wide operating temperature variations. These conditions often induce mechanical and optical failures, including cracking of display glass, delamination between bonded layers, formation of air gaps, optical distortion, loss of contrast, and degradation of long-term structural integrity. Such failures adversely affect display reliability, readability, and service life.
[0004] To address these issues, various optical bonding and adhesive solutions have been proposed for reinforcing LCD assemblies. However, existing adhesive formulations generally emphasize either high mechanical strength or high optical transparency. Adhesives optimized for mechanical rigidity often lack sufficient elasticity to absorb shock and vibration, leading to stress concentration and glass fracture. Conversely, adhesives optimized for optical clarity frequently exhibit inadequate mechanical damping or long-term durability under harsh environmental conditions.
[0005] Further, conventional optically clear adhesive formulations are often sensitive to thermal cycling, resulting in changes in mechanical properties, loss of adhesion, or optical degradation over extended periods of operation. Inconsistent curing behavior and limited control over cured-state mechanical characteristics further restrict the applicability of such adhesives in ruggedized LCD assemblies. As a result, existing solutions fail to provide a balanced and controllable combination of optical clarity, mechanical reinforcement, and environmental resilience required for reliable LCD operation in demanding conditions.
[0006] Accordingly, there exists a need for an improved optically transparent bonding medium formulation that enables controlled mechanical characteristics while maintaining optical performance, and that is suitable for use in ruggedized LCD assemblies subjected to shock, vibration, and thermal stress.
[0007] The reference to any prior art in this specification is not an acknowledgment or suggestion that such prior art forms part of the common general knowledge in any jurisdiction or that a person skilled in art could reasonably expect such prior art to be understood, regarded as relevant, or combined with other aspects of prior art.

BRIEF SUMMARY

[0008] One or more embodiments relate to a specially designed optically transparent bonding medium used to optically couple, strengthen and protect Liquid Crystal Display (LCD) assemblies that are intended to operate in demanding environments. The optically transparent bonding medium is formed by mixing two components, referred to as Part A of optically transparent bonding medium and Part B of optically transparent bonding medium, in a defined weight ratio. Part A of optically transparent bonding medium includes a polymer-based material, and Part B of optically transparent bonding medium includes a curing agent that reacts with Part A to form a solidified, transparent optically transparent bonding medium. The ratio between these two parts is controlled within a specified range to ensure consistent formation of the optically transparent bonding medium and to achieve the desired mechanical characteristics.
[0009] The formulation is adaptable to different types of polymer materials, including silicone, polyurethane, acrylic, and epoxy-based systems. The curing agent may include various types of hardeners or catalysts suitable for these materials. By controlling the mixing ratio between the two parts, the mechanical properties of the cured optically transparent bonding medium, such as hardness and stiffness, can be regulated.
[0010] The cured optically transparent bonding medium exhibits defined mechanical characteristics, including a specified hardness range, making it suitable for reinforcing display assemblies subjected to vibration, shock, and environmental stress.
[0011] In an embodiment, the invention also includes a method of manufacturing a ruggedized LCD assembly. In this method, a functional glass plate is positioned relative to the LCD panel to create a cavity. The two optically transparent bonding medium components are mixed in the specified ratio to form a optically transparent bonding medium, which is then introduced into the cavity. After curing, the optically transparent bonding medium forms a transparent bonding layer between the LCD panel and the functional glass plate. The assembly is then sealed to complete the ruggedized structure. Additional steps may include degassing the optically transparent bonding medium to remove air bubbles, controlling the dispensing process to ensure uniform filling, and performing curing in multiple stages. The method may also involve forming optically transparent bonding mediums on one or both sides of the LCD panel.
[0012] An embodiment of the present disclosure relates to an optically transparent bonding medium formulation for ruggedizing a Liquid Crystal Display (LCD) assembly and a method of manufacturing a ruggedized LCD assembly using the formulation. The disclosure addresses reinforcement of LCD assemblies through controlled formation of a cross-linked optically transparent bonding medium between an LCD panel and a functional glass plate.
[0013] In an embodiment, the formulation comprises a Part A of optically transparent bonding medium and a Part B of optically transparent bonding medium. The Part A of optically transparent bonding medium comprises a polymerizable base resin. The base resin includes at least one polymer selected from silicone polymers, polyurethane polymers, acrylic polymers, epoxy polymers, or combinations thereof. These polymer materials provide the foundational matrix of the optically transparent bonding medium before curing.
[0014] In an embodiment, the Part B of optically transparent bonding medium comprises a curing agent reactive with the base resin of the Part A of optically transparent bonding medium. The curing agent is selected from amine-based curing agents, polyamide curing agents, anhydride curing agents, isocyanate-based curing agents, peroxide initiators, photo initiators, platinum-based catalysts, tin-based catalysts, organometallic catalysts, or combinations thereof. Upon mixing, the curing agent reacts with the base resin to initiate cross-linking, thereby transforming the optically transparent bonding medium into a cured, cross-linked optically transparent bonding medium.
[0015] In an embodiment, the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium are mixed in a controlled weight ratio within a predefined range of 1:1 to 1:2. Adjustment of the weight ratio within this range enables control of cross-link density in the cured optically transparent bonding medium. The cured optically transparent bonding medium exhibits an elastic modulus within a predefined range expressed in MPa. By controlling the weight ratio between the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium, the mechanical properties of the cured optically transparent bonding medium, including hardness and stiffness characteristics, are regulated while maintaining optical clarity.
[0016] In an embodiment, the formulation is configured to form an optically transparent bonding medium layer between an LCD glass substrate and a functional glass plate. The functional glass plate may comprise thermally active transparent glass, optically coupled transparent glass, or glass incorporating electrically conductive transparent layer (ECTL) coating. The resulting cross-linked optically transparent bonding medium suitable for reinforcing LCD assemblies.
[0017] An embodiment of the disclosure relates to a method of manufacturing a ruggedized Liquid Crystal Display (RLCD) assembly using the optically transparent bonding medium formulation. The method comprises providing an LCD panel and positioning at least one functional glass plate relative to the LCD panel to define an interfacial cavity and at least one feed point. An optically transparent bonding medium mixture is prepared by mixing the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium in the controlled weight ratio within the predefined range of 1:1 to 1:2. The optically transparent bonding medium is then introduced into the interfacial cavity through the feed point to form an optically transparent bonding medium between the LCD panel and the functional glass plate. In certain embodiments, preparation of the optically transparent bonding medium may further include degassing before introduction into the interfacial cavity to reduce entrapped air. The introduced optically transparent bonding medium is subsequently cured to form the cross-linked optically transparent bonding medium within the interfacial cavity. Curing may comprise a first curing stage at room temperature, followed by a second curing stage at an elevated temperature. After curing, the feed point is sealed to complete the ruggedized LCD assembly.
[0018] In certain embodiments, positioning of the functional glass plate comprises bonding the functional glass plate to the LCD panel using a spacer element defining a predetermined cavity thickness. The method may further comprise pressure-controlled dispensing of the optically transparent bonding medium to achieve substantially void-free filling of the interfacial cavity. In some embodiments, the method includes forming a first optically transparent bonding medium between the LCD panel and a first functional glass plate and forming a second optically transparent bonding medium between the LCD panel and a second functional glass plate.
[0019] Accordingly, the disclosure provides a composition and a manufacturing method for forming a cross-linked optically transparent bonding medium layer between an LCD panel and a functional glass plate for ruggedized display assemblies.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
[0021] FIGURE 1 illustrates an exemplary optically transparent bonding medium arrangement in a Ruggedized Liquid Crystal Display (RLCD) assembly, in accordance with an embodiment of the present disclosure.
[0022] FIGURE 2 illustrates a flowchart for a method of manufacturing a RLCD assembly using a ratio-controlled optically transparent bonding medium formulation, in accordance with an embodiment of the present disclosure.
[0023] Additional features and aspects of the present disclosure will become apparent from the accompanying drawings and the detailed description set forth herein. The features and characteristics of the disclosed subject matter will be better understood with reference to the following description of exemplary embodiments as illustrated in the accompanying FIGURES. It will be appreciated that the disclosed subject matter is capable of various modifications and alternative implementations without departing from the scope of the appended claims. Accordingly, the drawings and the description are to be regarded as illustrative rather than limiting in nature.

DETAILED DESCRIPTION

[0024] Terminology
[0025] Brief definitions of terms used throughout this application are given below.
[0026] The terms “connected” or “coupled” and related terms are used in an operational sense and are not necessarily limited to a direct connection or coupling. Thus, for example, two devices may be coupled directly, or via one or more intermediary media or devices. As another example, devices may be coupled in such a way that information can be passed there between, while not sharing any physical connection with one another. Based on the disclosure provided herein, one of the ordinary skill in the art will appreciate a variety of ways in which connection or coupling exists in accordance with the aforementioned definition.
[0027] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0028] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context dictates otherwise.
[0029] The phrases “in an embodiment,” “according to one embodiment,” and the like generally mean the particular feature, structure, or characteristic following the phrase is included in at least one embodiment of the present disclosure and may be included in more than one embodiment of the present disclosure. Importantly, such phrases do not necessarily refer to the same embodiment.
[0030] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those of ordinary skill in the art. Moreover, all statements herein reciting embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure).
[0031] Certain exemplary embodiments of the present invention are described below and illustrated in the accompanying figures. The embodiments described are only for purposes of illustrating the present invention and should not be interpreted as limiting the scope of the invention, which, of course, is limited only by the claims below. Other embodiments of the invention and certain modifications and improvements of the described-embodiments will occur to those skilled in the art and all such alternate embodiments, modifications and improvements are within the scope of the present invention.
[0032] According to common practice, the various features of the drawings discussed below are not necessarily drawn to scale. Dimensions of various features and elements in the drawings may be expanded or reduced to more clearly illustrate the embodiments of the invention.
[0033] FIGURE 1 illustrates an exemplary optically transparent bonding medium 106 arrangement in a ruggedized Liquid Crystal Display (LCD) assembly, in accordance with an embodiment of the present disclosure. In an embodiment, the assembly includes an LCD panel 102 having a viewing screen, a functional glass plate 104 positioned relative to the LCD panel 102, and an optically transparent bonding medium 106 disposed between the LCD panel 102 and the functional glass plate 104. The optically transparent bonding medium 106 provides a transparent bonding interface between the LCD panel 102 and the functional glass plate 104.
[0034] In an embodiment, the LCD panel 102 may include a liquid crystal display module configured to present visual information to a user through a viewing screen. The LCD panel 102 may include a display glass substrate, a liquid crystal layer disposed between opposing glass substrates, and a backlight assembly positioned behind the liquid crystal layer. The display glass substrate may be formed from strengthened or tempered glass suitable for electronic display applications. The viewing screen of the LCD panel 102 represents the outward-facing surface through which image content is observed.
[0035] In an embodiment, the LCD panel 102 may be a Commercial Off-The-Shelf (COTS) display module adapted for integration into ruggedized systems. The LCD panel 102 may be designed for operation within a defined electrical input range and may include driver circuitry, control interfaces, and protective coatings. In alternate embodiments, the LCD panel 102 may be customized for specific environmental or operational requirements, including wide-temperature operation, sunlight readability, or high-brightness performance.
[0036] In an embodiment, the LCD panel 102 may include a peripheral frame or support structure surrounding the display glass substrate. The frame may provide mechanical support and facilitate mounting within an enclosure. In some embodiments, the LCD panel 102 may include pre-existing protective layers, cover glass, or touch-sensing layers, depending on application requirements.
[0037] In certain embodiments, the LCD panel 102 may be configured for operation in environments subject to mechanical shock, vibration, temperature variations, and humidity. The structural characteristics of the LCD panel 102 may influence its interaction with adjacent components within the ruggedized assembly. The physical dimensions, thickness, and material composition of the LCD panel 102 may vary depending on display size and application category.
[0038] In an embodiment, the functional glass plate 104 may comprise a transparent glass substrate positioned relative to the LCD panel 102 within the ruggedized Liquid Crystal Display (RLCD) assembly. The functional glass plate 104 may be configured to provide one or more functional enhancements to the LCD assembly.
[0039] In an embodiment, the functional glass plate 104 may include a thermally active transparent glass. The thermally active transparent glass may include an integrated heating element configured to generate heat when electrically energized. The heating element may be formed as a transparent conductive layer or an embedded conductive structure within or on the surface of the glass substrate. The thermally active transparent glass may be configured to mitigate condensation, frost formation, or temperature-induced performance variations during operation in harsh environmental conditions.
[0040] In another embodiment, the functional glass plate 104 may comprise a glass substrate with an optically coupled layer coating formed on at least one surface. The optically coupled layer coating may be configured to reduce surface reflectivity and improve visibility of the LCD viewing screen under ambient lighting conditions.
[0041] In an alternate embodiment, the functional glass plate 104 may comprise a glass substrate incorporating an Electrically Conductive Transparent Layer (ECTL) coating. The ECTL coating may be configured to reduce or shield the ECTL, affecting the LCD assembly. The ECTL coating may be formed as a transparent conductive layer disposed on the glass substrate.
[0042] In certain embodiments, the RLCD assembly may include more than one functional glass plate 104. For example, a first functional glass plate may comprise thermally active transparent glass, while a second functional glass plate may comprise glass including an optically coupled layer and ECTL coatings. The functional glass plates 104 may be positioned on one or both sides of the LCD panel 102, depending on application requirements.
[0043] In an embodiment, the dimensions and thickness of the functional glass plate 104 may be selected based on the size of the LCD panel 102 and the structural requirements of the ruggedized assembly. The functional glass plate 104 may cooperate with adjacent bonding materials to form a mechanically reinforced display structure.
[0044] In an embodiment, the optically transparent bonding medium 106 comprises a two-part reactive optically transparent bonding medium formulation including a Part A of optically transparent bonding medium and a Part B of optically transparent bonding medium. The Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium are maintained separately before use and are mixed in a controlled weight ratio to form a curable optically transparent bonding medium capable of forming a cross-linked optically transparent bonding medium upon curing.
[0045] In an embodiment, the Part A of optically transparent bonding medium comprises a polymerizable base resin. The base resin comprises at least one polymer selected from the group consisting of silicone polymers, polyurethane polymers, acrylic polymers, epoxy polymers, and combinations thereof. The polymerizable base resin is optically transparent in an uncured state and is capable of forming a transparent cross-linked polymer network after reaction with a curing agent.
[0046] In one embodiment, the base resin comprises a silicone polymer configured for addition-cure or condensation-cure cross-linking. In another embodiment, the base resin comprises an epoxy polymer containing reactive epoxide groups. In another embodiment, the base resin comprises a polyurethane precursor containing hydroxyl or other reactive functional groups. In an alternate embodiment, the base resin comprises an acrylic polymerizable composition capable of free-radical or photo-initiated curing.
[0047] In certain embodiments, the Part A of optically transparent bonding medium may comprise a combination of two or more of the aforementioned polymers to tailor optical and mechanical properties. The viscosity of the Part A of optically transparent bonding medium may be selected to permit uniform mixing with the Part B of optically transparent bonding medium and controlled formation of a continuous transparent bonding layer.
[0048] In an embodiment, the Part B of optically transparent bonding medium comprises a curing agent reactive with the base resin of the Part A of optically transparent bonding medium to initiate cross-linking. The curing agent is selected from amine-based curing agents, polyamide curing agents, anhydride curing agents, isocyanate-based curing agents, peroxide initiators, photo-initiators, platinum-based catalysts, tin-based catalysts, organometallic catalysts, and combinations thereof.
[0049] In one embodiment, when the Part A of the optically transparent bonding medium comprises an epoxy polymer, the Part B of the optically transparent bonding medium may comprise an amine-based curing agent, polyamide curing agent, or anhydride curing agent. In another embodiment, when the Part A of the optically transparent bonding medium comprises a polyurethane precursor, the Part B of the optically transparent bonding medium may comprise an isocyanate-based curing agent. In another embodiment, when the Part A of the optically transparent bonding medium comprises an acrylic polymerizable composition, the Part B of the optically transparent bonding medium may comprise a peroxide initiator or a photo-initiator. In yet another embodiment, when the Part A of the optically transparent bonding medium comprises a silicone polymer, the Part B of the optically transparent bonding medium may comprise a platinum-based catalyst, tin-based catalyst, or organometallic catalyst.
[0050] In an embodiment, the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium are mixed in a controlled weight ratio within a predefined range of 1:1 to 1:2 to form an optically transparent bonding medium mixture. The controlled weight ratio governs the stoichiometric balance between reactive functional groups of the base resin and the curing agent.
[0051] In an embodiment, cross-link density of the cured optically transparent bonding medium is controlled by adjustment of the weight ratio between the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium within the predefined range. Increasing or decreasing the proportion of the curing agent relative to the base resin modifies the extent of cross-link formation and thereby regulates the mechanical characteristics of the cured optically transparent bonding medium.
[0052] In an embodiment, the cured optically transparent bonding medium further exhibits an elastic modulus within a predefined range of 0.3 - 6.0 MPa. The elastic modulus corresponds to the stiffness characteristics of the cured optically transparent bonding medium and is influenced by the cross-link density established during curing. The elastic modulus may be determined using tensile or dynamic mechanical testing methods.
[0053] In an embodiment, the formulation is configured to form the Optically transparent bonding medium 106 as an optically transparent optically transparent bonding medium between an LCD glass substrate and a functional glass plate 104. The cross-linked optically transparent bonding medium forms a continuous bonding interface while maintaining light transmission through the display assembly.
[0054] In an embodiment, the functional glass plate may comprise thermally active transparent glass, optically coupled transparent glass, or glass incorporating electrically conductive transparent layer (ECTL) coating, and the cured optically transparent bonding medium 106 is compatible with such functional glass structures.
[0055] FIGURE 2 illustrates a flowchart 200 for a method of manufacturing a ruggedized Liquid Crystal Display (RLCD) assembly using a ratio-controlled optically transparent bonding medium formulation, in accordance with an embodiment of the present disclosure. The method begins at step 202.
[0056] At step 204, the method includes providing an LCD panel. In an embodiment, the LCD panel comprises a liquid crystal display module including a viewing screen, a liquid crystal layer disposed between transparent substrates, and associated driving circuitry. The LCD panel may include a thin-film transistor (TFT) matrix, polarizing layers, and a backlight assembly configured to provide uniform illumination.
[0057] In an embodiment, the LCD panel may be a Commercial Off-The-Shelf (COTS) display module is selected based on size, resolution, brightness, and operating temperature characteristics. In another embodiment, the LCD panel may be a customized module designed for operation in extended temperature environments.
[0058] In certain embodiments, before bonding, the surface of the LCD panel may be cleaned to remove particulate matter, organic contaminants, or surface residues that could interfere with the formation of a uniform optically transparent bonding medium. Surface preparation may include solvent cleaning, air blowing, or plasma treatment, depending on application requirements.
[0059] At step 206, the method includes positioning at least one functional glass plate relative to the LCD panel to define an interfacial cavity and at least one feed point.
[0060] In an embodiment, the functional glass plate is aligned with the viewing surface of the LCD panel such that a defined gap is maintained between the two components. A spacer element may be applied along peripheral regions to establish a predetermined cavity thickness corresponding to a target thickness of the optically transparent bonding medium.
[0061] In one embodiment, the spacer element comprises a wide-temperature-range double-sided adhesive tape having a predefined thickness. The thickness of the spacer element determines the final thickness of the cured optically transparent bonding medium and may be selected based on display size and mechanical reinforcement requirements.
[0062] In an embodiment, the functional glass plate comprises thermally active transparent glass incorporating a transparent conductive heating element. In another embodiment, the functional glass plate comprises glass including an optically coupled transparent coating layer. In another embodiment, the functional glass plate comprises glass incorporating an electrically conductive transparent layer (ECTL) shielding layer. In alternate embodiments, multiple functional glass plates may be positioned on opposite sides of the LCD panel. At least one feed point is intentionally maintained in the spacer region to permit introduction of the optically transparent bonding medium mixture into the interfacial cavity at a later stage.
[0063] In an embodiment, after positioning the functional glass plate and defining the interfacial cavity, a sealing layer comprising an adhesive material is applied along the bonded peripheral edges of the LCD panel and the functional glass plate while maintaining the feed point open. The sealing layer serves to contain the optically transparent bonding medium mixture within the interfacial cavity during subsequent injection and enhances the structural integrity of the assembly.
[0064] At step 208, the method includes preparing an optically transparent bonding medium mixture by mixing a Part A of optically transparent bonding medium and a Part B of optically transparent bonding medium in the controlled weight ratio within the predefined range of 1:1 to 1:2. In an embodiment, the Part A of optically transparent bonding medium comprises a polymerizable base resin selected from silicone polymers, polyurethane polymers, acrylic polymers, epoxy polymers, or combinations thereof. In an embodiment, the Part B of optically transparent bonding medium comprises a curing agent reactive with the base resin of the Part A optically transparent bonding medium. The curing agent may be selected from amine-based curing agents, polyamide curing agents, anhydride curing agents, isocyanate-based curing agents, peroxide initiators, photo-initiators, platinum-based catalysts, tin-based catalysts, organometallic catalysts, or combinations thereof.
[0065] In an embodiment, the required amounts of the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium are measured using a weighing device to maintain the controlled weight ratio. The two components are mixed until a substantially homogeneous optically transparent bonding medium is obtained.
[0066] In certain embodiments, the mixed optically transparent bonding medium may be filtered through a mesh filter to remove particulate contaminants before degassing. In another embodiment, the optically transparent bonding medium is placed in a vacuum chamber for a predefined duration determined based on the volume of the optically transparent bonding medium to remove entrapped air bubbles. The air-bubble-free optically transparent bonding medium may then be transferred into a dispensing barrel or container configured for controlled injection into the interfacial cavity.
[0067] In an embodiment, adjustment of the weight ratio within the predefined range influences the cross-link density of the cured optically transparent bonding medium and thereby regulates mechanical characteristics, including hardness and elastic modulus.
[0068] At step 210, the method includes introducing the optically transparent bonding medium mixture into the interfacial cavity through the feed point to form an optically transparent bonding medium between the LCD panel and the functional glass plate. In an embodiment, the optically transparent bonding medium is dispensed through a dispensing barrel mounted above the feed point and connected to an air-pressure device. Controlled air pressure enables smooth and uniform filling of the cavity.
[0069] In certain embodiments, introduction of the optically transparent bonding medium may be visually monitored using an air-bubble detection or monitoring system positioned relative to the LCD panel to ensure proper progression of the optically transparent bonding medium without air trapping. The optically transparent bonding medium flows within the interfacial cavity and spreads across the bonding interface, displacing air and forming a continuous transparent layer.
[0070] In an embodiment, after optically transparent bonding medium filling is completed, the RLCD panel may be removed from a dispensing fixture and placed horizontally on a flat surface to allow the optically transparent bonding medium to settle at room temperature for a predefined duration to achieve uniform layer thickness.
[0071] At step 212, the method includes curing the optically transparent bonding medium to form a cross-linked optically transparent bonding medium. In an embodiment, curing comprises a first curing stage at room temperature to stabilize the optically transparent bonding medium and minimize internal stress, followed by a second curing stage at an elevated temperature in an oven for a predefined duration to complete cross-link formation and strengthen the bonding structure. Upon curing, the optically transparent bonding medium exhibits a an elastic modulus within a predefined range 0.3 - 6.0 MPa. These mechanical characteristics are influenced by the controlled mixing ratio between the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium.
[0072] At step 214, the feed point region may be cleaned, for example, using a solvent and lint-free material, to remove residual optically transparent bonding medium material. A sealing adhesive or encapsulant is then applied to close the feed point and prevent ingress of moisture, light leakage, dust accumulation, or environmental contamination.
[0073] In certain embodiments, the sealing material is allowed to cure at room temperature for a predefined duration to complete encapsulation of the ruggedized LCD assembly.
[0074] In an alternate embodiment, the method further comprises forming a first optically transparent bonding medium between the LCD panel and a first functional glass plate and forming a second optically transparent bonding medium between the LCD panel and a second functional glass plate, each layer being formed in accordance with steps 208 through 212.
[0075] In an embodiment, the ruggedized Liquid Crystal Display (RLCD) panel includes at least one optically transparent bonding medium layer formed between the LCD panel glass and one or more functional glass plates. In certain embodiments, the first optically transparent bonding medium is formed between the LCD panel glass and the thermally active transparent glass, and the second optically transparent bonding medium is formed between the LCD panel glass and the functional glass plate incorporating optically coupled layer and electrically conductive transparent layer (ECTL) coatings.
[0076] The optically transparent bonding mediums are formed from a two-part optically transparent bonding medium including a Part-A of optically transparent bonding medium and a Part-B of optically transparent bonding medium mixed in a controlled weight ratio within a range of 1:1 to 1:2. The controlled ratio enables proper cross-linking and uniform encapsulation, resulting in structural reinforcement and improved resistance to impact and vibration while maintaining optical clarity.
[0077] A wide-temperature-range double-sided adhesive tape is used as a spacer to define an interfacial cavity of predetermined thickness between the LCD panel and the functional glass plate. A designated feed point is intentionally maintained to enable controlled optically transparent bonding medium injection. Peripheral edge sealing is applied prior to optically transparent bonding medium filling while maintaining the feed point open.
[0078] The optically transparent bonding medium is prepared under controlled conditions by accurately weighing and mixing the two components, followed by filtration and vacuum degassing to eliminate contaminants and entrapped air. The degassed optically transparent bonding medium is introduced into the interfacial cavity through the feed point using a pressure-controlled dispensing system, optionally monitored to prevent air trapping and void formation.
[0079] Following injection, the assembly undergoes a curing process including a room-temperature phase to allow uniform settling and a subsequent elevated-temperature phase to complete cross-linking. After curing, the feed point is cleaned and sealed using a contamination-resistant adhesive. The resulting optically transparent bonding mediums provide uniform thickness, enhanced structural integrity, improved optical performance, and environmental durability suitable for rugged applications.
[0080] In an embodiment, the completed RLCD assembly may be placed in a protective storage enclosure to prevent contamination or mechanical damage before deployment. The method ends at step 216.
[0081] The present disclosure provides a ratio-controlled optically transparent bonding medium formulation and associated manufacturing method for ruggedizing Liquid Crystal Display (LCD) assemblies, offering several technical and operational advantages over conventional adhesive bonding approaches.
[0082] An advantage of the present disclosure is the provision of controlled mechanical reinforcement of the LCD assembly. By maintaining a defined weight ratio between the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium within a predefined range of 1:1 to 1:2, the cross-link density of the cured optically transparent bonding medium is regulated. This enables tuning of hardness and elastic modulus within predefined ranges, thereby achieving a balanced combination of structural rigidity and controlled compliance suitable for ruggedized applications.
[0083] Another advantage of the present disclosure is enhanced resistance to mechanical shock and vibration. The cross-linked optically transparent bonding medium formed between the LCD panel and the functional glass plate distributes mechanical stresses across the bonding interface, thereby reducing the likelihood of localized stress concentration, glass cracking, and delamination during high-impact or high-vibration operation.
[0084] A further advantage lies in improved durability under thermal cycling conditions. The controlled curing process, including a room-temperature stage followed by an elevated-temperature stage, facilitates uniform cross-link formation and stable adhesion. The resulting bonded structure maintains mechanical integrity across wide operating temperature ranges typically encountered in defence, aerospace, railway, and industrial environments. An additional advantage is long-term optical stability. The optically transparent bonding medium forms a transparent bonding interface between the LCD glass substrate and the functional glass plate without introducing visible distortion, haze, or bubble formation when prepared and injected under controlled conditions, including degassing and pressure-controlled dispensing. Uniform optically transparent bonding medium distribution and void-free filling improve image clarity and viewing performance.
[0085] The present disclosure further enables ruggedization of Commercial Off-The-Shelf (COTS) LCD modules without requiring structural redesign of the LCD panel itself. This allows cost-effective adaptation of standard display modules for deployment in demanding mechanical and environmental conditions.
[0086] Accordingly, the disclosed formulation and method provide a balanced combination of mechanical reinforcement, optical clarity, thermal stability, and environmental robustness not simultaneously achieved by conventional adhesive bonding solutions.
[0087] While embodiments of the present disclosure have been illustrated and described, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the disclosure, as described in the claims.
[0088] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C,…, and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
[0089] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions, or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art. , Claims:CLAIMS

We Claim:
1. A ratio-controlled optically transparent bonding medium formulation for ruggedizing a Liquid Crystal Display (LCD) assembly, the formulation comprising:
a Part A of optically transparent bonding medium comprising a polymerizable base resin, wherein the base resin comprises at least one polymer selected from the group consisting of silicone polymers, polyurethane polymers, acrylic polymers, epoxy polymers, and combinations thereof;
a Part B of optically transparent bonding medium comprising a curing agent reactive with the base resin of the Part A to form a cross-linked optically transparent bonding medium;
wherein the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium are mixed in a controlled weight ratio within a predefined range of 1:1 to 1:2 to form the optically transparent bonding medium.
2. The formulation as claimed in claim 1, wherein the curing agent of the Part B of optically transparent bonding medium is selected from the group consisting of amine-based curing agents, polyamide curing agents, anhydride curing agents, isocyanate-based curing agents, peroxide initiators, photo-initiators, platinum-based catalysts, tin-based catalysts, organometallic catalysts, and combinations thereof.
3. The formulation as claimed in claim 1, wherein cross-link density of the optically transparent bonding medium is controlled by adjustment of the weight ratio between the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium.
4. The formulation as claimed in claim 1, wherein the cured optically transparent bonding medium exhibits an elastic modulus in a predefined range 0.3 - 6.0 MPa.
5. The formulation as claimed in claim 1, wherein the formulation is configured to form an optically transparent bonding medium between an LCD glass substrate and a functional glass plate.
6. The formulation as claimed in claim 5, wherein the functional glass plate comprises at least one of: thermally active transparent glass, optically coupled transparent glass, and Electrically Conductive Transparent Layer (ECTL) coated glass.
7. A method of manufacturing a ruggedized Liquid Crystal Display (RLCD) assembly using a ratio-controlled optically transparent bonding medium, the method comprising:
providing an LCD panel;
positioning at least one functional glass plate relative to the LCD panel to define an interfacial cavity and at least one feed point;
preparing an optically transparent bonding medium mixture by mixing a Part A of optically transparent bonding medium and a Part B of optically transparent bonding medium in the controlled weight ratio within the predefined range of 1:1 to 1:2;
wherein the Part A of optically transparent bonding medium comprises a polymerizable base resin, wherein the base resin comprises at least one polymer selected from the group consisting of silicone polymers, polyurethane polymers, acrylic polymers, epoxy polymers, and combinations thereof;
wherein the Part B of optically transparent bonding medium comprises a curing agent reactive with the base resin of the Part A optically transparent bonding medium, wherein the curing agent is selected from the group consisting of amine-based curing agents, polyamide curing agents, anhydride curing agents, isocyanate-based curing agents, peroxide initiators, photo-initiators, platinum-based catalysts, tin-based catalysts, organometallic catalysts, and combinations thereof;
introducing the optically transparent bonding medium mixture into the interfacial cavity through the feed point to form an optically transparent bonding medium between the LCD panel and the functional glass plate;
curing the optically transparent bonding medium to form a cross-linked optically transparent bonding medium; and
sealing the feed point after curing to complete the ruggedized LCD assembly.
8. The method as claimed in claim 7, wherein positioning the functional glass plate comprises bonding the functional glass plate to the LCD panel using a spacer element defining a predetermined cavity thickness.
9. The method as claimed in claim 7, wherein preparing the optically transparent bonding medium further comprises degassing the optically transparent bonding medium prior to introduction into the interfacial cavity.
10. The method as claimed in claim 7,
wherein introducing the optically transparent bonding medium comprises pressure-controlled dispensing to achieve substantially void-free filling of the interfacial cavity;
wherein curing comprises a first curing stage at room temperature, followed by a second curing stage at an elevated temperature; and
wherein forming the optically transparent bonding medium comprises forming a first optically transparent bonding medium between the LCD panel and a first functional glass plate, and forming a second optically transparent bonding medium between the LCD panel and a second functional glass plate.
11. The method as claimed in claim 7, wherein the functional glass plate comprises at least one of: thermally active transparent glass, optically coupled transparent glass, and Electrically Conductive Transparent Layer (ECTL) coated glass.
12. The method as claimed in claim 7, wherein cross-link density of the optically transparent bonding medium is controlled by adjustment of the weight ratio between the Part A of optically transparent bonding medium and the Part B of optically transparent bonding medium.
13. The method as claimed in claim 7, wherein the cured optically transparent bonding medium exhibits an elastic modulus in a predefined range 0.3 - 6.0 MPa.