Low alkali high transmission glass

Abstract

The present invention relates to low-alkali high-transmission glasses, compounds, compositions, articles, devices, and methods for making light guide plates, and back light units including glass-made light guide plates. In some embodiments, provided light guide plates (LGP) have optical properties similar to or better than PMMA-made light guide plates, and superior mechanical properties, such as rigidity, CTE, and dimensional stability under high humidity conditions, compared to PMMA light guide plates.

Description

[0001] This application is a divisional application of patent application No. 201980032509.5, filed on May 1, 2019, entitled "Low-alkali metal high-transmittance glass".

[0002] Cross-reference to related applications

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 665151, filed May 1, 2018, in accordance with patent laws and regulations. This application relies on the full contents of the provisional application, which are incorporated herein by reference. Technical Field

[0004] The target aspect relates to compounds, compositions, articles, apparatus and methods for manufacturing light guide plates, backlight units and other articles employing high-transmittance glass. Background Technology

[0005] Side-lit backlight units include a light guide plate (LGP), which is typically made of a high-transmittance plastic material, such as polymethyl methacrylate (PMMA). Although plastic materials exhibit excellent properties such as light transmission, they have rather poor mechanical properties, such as rigidity, coefficient of thermal expansion (CTE), and hygroscopicity.

[0006] Therefore, there is a desire to provide improved articles with enhanced optical performance in terms of light transmission, sunlight exposure, scattering, and optical coupling, as well as superior mechanical properties in terms of rigidity, CTE, and hygroscopicity. Other applications of such articles may include planar waveguides, automotive, and other display applications. Summary of the Invention

[0007] In some embodiments, the principles and embodiments of the present invention relate to a light guide plate for a backlight unit. In some embodiments, the glass article or light guide plate (in some instances) comprises a glass sheet having a front side having a width and a height, a back side facing the front side, and a thickness between the front and back sides, and forming four edges surrounding the front and back sides, wherein the glass sheet is substantially free of alkali metals and contains about 64 mol% to about 71 mol% of SiO2, about 9 mol% to about 12 mol% of Al2O3, about 7 mol% to about 12 mol% of B2O3, about 1 mol% to about 3 mol% of MgO, about 6 mol% to about 11.5 mol% of CaO, about 0 mol% to about 2 mol% of SrO, about 0 mol% to about 0.1 mol% of BaO, about 0.01 mol% to about 0.5 mol% of SnO2, less than 1 ppm (parts per million) each of Co (cobalt), Ni (nickel), and Cr (chromium) and less than about 50 ppm of Fe (iron).

[0008] In other embodiments, an exemplary glass article comprises a glass sheet having a front side having a width and a height, a back side facing the front side, and a thickness between the front side and the back side, and forming four edges surrounding the front side and the back side, wherein the glass sheet comprises about 64 mol% to about 71 mol% of SiO2, about 9 mol% to about 12 mol% of Al2O3, about 7 mol% to about 12 mol% of B2O3, about 1 mol% to about 3 mol% of MgO, about 6 mol% to about 11.5 mol% of CaO, about 0 mol% to about 2 mol% of SrO, about 0 mol% to about 0.1 mol% of BaO, about 0.01 mol% to about 0.5 mol% of SnO2, less than 0.5 mol% of any one or a combination of Na2O, K2O, and Li2O, less than 1 ppm of each of Co, Ni, and Cr, and less than about 50 ppm of Fe.

[0009] In other embodiments, an exemplary glass article may comprise a glass sheet having a front side having a width and a height, a back side facing the front side, and a thickness between the front and back sides, and forming four edges surrounding the front and back sides, wherein the glass sheet comprises about 64 mol% to about 71 mol% of SiO2, about 9 mol% to about 12 mol% of Al2O3, about 7 mol% to about 12 mol% of B2O3, about 1 mol% to about 3 mol% of MgO, about 6 mol% to about 11.5 mol% of CaO, about 0 mol% to about 2 mol% of SrO, about 0 mol% to about 0.1 mol% of BaO, about 0.01 mol% to about 0.5 mol% of SnO2, an alkali metal to Al2O3 ratio of less than or equal to 0.5, less than 1 ppm of Co, Ni and Cr, and less than about 50 ppm of Fe.

[0010] The advantages of such glasses and articles include that CTE and / or other properties are comparable to or close to other glass substrates commonly used in LCD display devices, improving compatibility with these substrates. Additionally, the exemplary glasses and articles do not require modification to prevent surface weathering.

[0011] Additional features and advantages of the present invention will be detailed below and will become clearer to some extent when those skilled in the art refer to or practice the methods described, including the following detailed description of embodiments, claims and drawings.

[0012] It should be understood that the foregoing summary and the following detailed description present different embodiments of the invention and are intended to provide an overview or framework to understand the nature and characteristics of the claims. The accompanying drawings provide a further understanding of the invention and are therefore incorporated into and constitute a part of the specification. The drawings depict different embodiments of the invention and, together with the description of implementation, serve to explain the principles and operation of the invention. Attached Figure Description

[0013] The detailed explanation below will be further understood after referring to the following diagrams.

[0014] Figure 1 This is a schematic diagram of an exemplary light guide plate embodiment;

[0015] Figure 2 It is a graph showing the percentage of optical coupling versus the edge spacing between the LED and the LGP;

[0016] Figure 3 This is a cross-sectional view of an exemplary LCD panel with an LGP according to one or more embodiments;

[0017] Figure 4 This is a cross-sectional view of an exemplary LCD panel with an LGP, according to another embodiment;

[0018] Figure 5 This is a schematic diagram of an LGP with an adhesive pad according to an additional embodiment; and

[0019] Figure 6 This is a graph showing the percentage of transmission over a 500-millimeter (mm) path, measured in some embodiments. Detailed Implementation

[0020] This document describes a light guide plate, a method for manufacturing a light guide plate, a backlight unit, and other articles of manufacture using a substrate according to embodiments of the present invention.

[0021] Currently, light guide plates used in LCD backlight applications are generally made of PMMA material because PMMA exhibits excellent light transmittance at visible light wavelengths. However, PMMA has mechanical problems, which pose challenges to the mechanical design of large-size displays (such as those with a diagonal of 50 inches and above), such as rigidity, moisture absorption, and coefficient of thermal expansion (CTE).

[0022] However, exemplary glass-based LGPs are superior to LGPs made of plastics such as PMMA due to the greater rigidity, better hygroscopicity, and lower CTE of glass. According to the present invention, exemplary LGPs can provide tunable color shifts that vary with the glass composition. For an exemplary glass light guide plate, the color shift Δy can be expressed as Δy = y(L2) - y(L1), where L2 and L1 are Z positions away from the source emission (e.g., LED or others) along the panel or substrate direction, where L2 - L1 = 0.5 meters, and a small difference between point 1 and point 2 will translate into a lower color shift for the corresponding LGP. To achieve a low color shift, the absorption curve of the exemplary LGP should have a certain shape; for example, the blue absorption at 450 nm should be less than the red absorption at 630 nm. Therefore, the greater the difference between the blue absorption and the red absorption, the lower the color shift of the LGP. In an exemplary embodiment, specifically, the optical absorption control of Cr and Ni can be achieved by manipulating the optical properties of the glass.

[0023] In terms of rigidity, traditional LCD panels are made of two thin glass sheets (a color filter substrate and a TFT substrate), PMMA photoconductors, and multiple thin plastic films (diffusing film, dual brightness enhancement film (DBEF), etc.). Due to the poor elastic modulus of PMMA, the overall structural rigidity of the LCD panel is insufficient, requiring additional mechanical structures to provide rigidity. It should be noted that the Young's modulus of PMMA is approximately 2 gigapascals (GPa), while some exemplary glasses have Young's moduli of approximately 60 GPa to 90 GPa or higher.

[0024] Regarding moisture absorption, humidity tests show that PMMA is very sensitive to humidity, with dimensional changes reaching approximately 0.5%. For a one-meter-long PMMA panel, a 0.5% change would increase the length by 5 mm, a significant impact that makes the mechanical design of the corresponding backlight unit extremely challenging. Traditional solutions to this problem include leaving an air gap between the light-emitting diode (LED) and the PMMA light guide plate (LGP) to allow the material to expand. The problem with this method is that light coupling is heavily affected by the distance between the LED and the LGP, causing the display brightness to vary with humidity. Figure 2 This is a graph showing the percentage of optical coupling versus the edge spacing between the LED and LGP. (Refer to...) Figure 2 The relationship shown illustrates the shortcomings of traditional methods for solving PMMA problems. More specifically, Figure 2 The figure shows a curve illustrating the effect of light coupling on the distance between the LED and the LGP, assuming that the height of both is 2 mm. It is observed that the greater the distance between the LED and the LGP, the worse the light coupling efficiency between them.

[0025] As for CTE, PMMA's CTE is approximately 75E-6℃. -1 It also has a relatively low thermal conductivity (0.2 W / m / K), and the CTE of some glasses is about 8E-6℃. -1 The thermal conductivity (CTE) is 0.8 W / m / K. Other glasses may have different CTEs, and this disclosure should not limit the scope of the appended claims. PMMA also has a transition temperature of approximately 105°C. When used as an LGP, PMMA LGP material becomes very hot, and the low thermal conductivity makes heat dissipation difficult. Therefore, using glass instead of PMMA as the light guide material offers advantages; however, conventional glass has poorer transmittance than PMMA, mainly due to iron and other impurities. Several other parameters play an important role in the performance of glass light guides, such as surface roughness, waviness, and edge polishing quality.

[0026] In an exemplary embodiment, the LGP is disposed between the front optical film layer (e.g., a diffuser film, DBEF, etc.) and the back reflective film or other reflective feature structure (e.g., a lens, quantum dot, etc.). The reflective film directs light from the vertical plane of the LGP to the LCD, while the optical film modulates the light of the LCD. When white light interacts with these two layers and the LGP, some light may be scattered and absorbed, resulting in loss. This loss will cause color shift and / or reduced brightness. The magnitude of the color shift of the LGP is limited by the shape of the absorption curve of the visible spectrum, and thus by the base glass matrix, the concentration of mixed metals, and the redox state of the mixed metals within the LGP.

[0027] The cost associated with manufacturing LGPs can vary depending on the glass composition. For example, while melting process parameters can be manipulated to create an optical absorption shift in a particular glass composition, it is impossible to completely remove the absorption of impurities in the visible spectrum. Furthermore, high-purity raw materials (processed to contain trace amounts of impurities) can cost up to eight times more than standard raw materials in some cases. Therefore, it is important to design the glass composition to minimize the use of the most expensive raw materials. Conventional glass LGPs use sodium aluminum silicate compositions. However, the cost of this composition somewhat hinders profitability; therefore, the exemplary compositions described include borosilicate glass to reduce the cost of LGPs.

[0028] Figure 1 This is a schematic diagram of an exemplary light guide plate embodiment. The light guide plate includes a glass sheet 100, which has a first working surface 110 (which may be the front side) and a second working surface (which may be the back side) facing the first working surface. The first and second working surfaces may have a height H and a width W. The roughness of the first and / or second working surfaces may be less than 0.6 nanometers (nm), less than 0.5 nm, less than 0.4 nm, less than 0.3 nm, less than 0.2 nm, less than 0.1 nm, or about 0.1 nm to about 0.6 nm.

[0029] The glass sheet has a thickness T between its front and back sides, where the thickness forms the four edges. The thickness of the glass sheet can be less than the height and width of the front and back sides. In various embodiments, the sheet thickness can be less than 1.5% of the height of the front and / or back sides. Alternatively, the thickness T can be less than about 3 mm, less than about 2 mm, less than about 1 mm, or from about 0.1 mm to about 3 mm. The height, width, and thickness of the light guide plate can be configured and adjusted for LCD backlight applications.

[0030] The first edge 130 may be a light injection edge to receive light provided by, for example, a light-emitting diode (LED). The light injection edge allows light to be scattered at a transmission full width at half maximum (FWHM) angle of less than 12.8 degrees. The light injection edge can be obtained by grinding the edge without polishing it. The glass sheet may further include a second edge 140 adjacent to the light injection edge and a third edge facing and adjacent to the second edge, wherein the second edge and / or the third edge allows light to be scattered at a reflection FWHM angle of less than 12.8 degrees. The reflection diffusion angle of the second edge 140 and / or the third edge may be less than 6.4 degrees. It should be noted that although... Figure 1 The illustrated embodiment shows light injected into a single edge 130, but the aim is not to limit this, as light can be injected into any or more edges of the exemplary embodiment 100. For example, in some embodiments, light can be injected into both the first edge 130 and its opposite edges. This exemplary embodiment can be used in display devices with a wide and / or curved width W. Additional embodiments may inject light into the second edge 140 and its opposite edges, rather than the first edge 130 and / or its opposite edges. The thickness of the exemplary display device may be less than about 10 mm, less than about 9 mm, less than about 8 mm, less than about 7 mm, less than about 6 mm, less than about 5 mm, less than about 4 mm, less than about 3 mm, or less than about 2 mm.

[0031] Generally, LGPs use white or blue LEDs. The presence of transition metals in the glass creates absorption bands in the visible light region. These absorption bands reduce the amount of light passing through the glass (which viewers perceive as a decrease in LCD screen brightness) and lead to increased color shift. Therefore, exemplary embodiments control the presence of transition metals, including iron, nickel, and chromium (especially those that impair glass transmission and increase color shift due to band location and absorption coefficients (intensities),) to maximize brightness and minimize color shift. However, these exemplary embodiments utilize appropriate glass mesh structures to minimize the effects of absorption bands, shifting some bands to higher wavelengths, such as increasing transmittance at 450 and 550 nm.

[0032] In various embodiments, the glass composition of the glass sheet may contain an iron (Fe) concentration of less than 50 ppm. In some embodiments, the Fe concentration is less than 25 ppm, or in some embodiments, the Fe concentration is about 20 ppm or less. In additional embodiments, the glass sheet may be formed using a polished float glass process, a fusion drawing process, a slot drawing process, a redrawing process, or another suitable forming process.

[0033] According to one or more embodiments, the LGP may be made of glass comprising a colorless oxide component selected from glass forming agents SiO2, Al2O3, and / or B2O3. Exemplary glasses may also include flux to obtain advantageous melting and forming properties. Fluxes include alkaline earth metal oxides (MgO, CaO, SrO, ZnO, and BaO). In one embodiment, the glass composition contains about 64 mol% to about 71 mol% of SiO2, about 9 mol% to about 12 mol% of Al2O3, about 7 mol% to about 12 mol% of B2O3, about 1 mol% to about 3 mol% of MgO, about 6 mol% to about 11.5 mol% of CaO, about 0 mol% to about 2 mol% of SrO, about 0 mol% to about 0.1 mol% of BaO, about 0.01 mol% to about 0.5 mol% of SnO2, and is substantially free of alkaline earth metal oxides (Na2O, K2O, Li2O, etc.). The term "substantially none" as used herein should be interpreted as meaning that the glass does not contain the stated components unless intentionally batched or added during the corresponding melting process, and therefore the mol% of the stated components is negligible or less than 0.01 mol%. Other glass compositions include glass sheets having a glass composition of about 64 mol% to about 71 mol% SiO2, about 9 mol% to about 12 mol% Al2O3, about 7 mol% to about 12 mol% B2O3, about 1 mol% to about 3 mol% MgO, about 6 mol% to about 11.5 mol% CaO, about 0 mol% to about 2 mol% SrO, about 0 mol% to about 0.1 mol% BaO, about 0.01 mol% to about 0.5 mol% SnO2, and any alkaline earth metal oxide (Na2O, K2O, Li2O, etc.) or combination thereof less than 0.5 mol%. Such glass compositions also have a color shift of <0.005.

[0034] In some of these glass compositions, SiO2 is used as a base glass forming agent. In some embodiments, the concentration of SiO2 is greater than 60 mol% to provide glass with density and chemical durability suitable for display glass or light guide glass, and a liquidus temperature (liquidus viscosity) that allows the glass to be formed by drawing processes (e.g., fusion processes). As for the upper limit, generally, the SiO2 concentration is less than or equal to about 80 mol%, allowing batches to be melted using conventional mass melting techniques, such as Joule melting in a refractory furnace. As the SiO2 concentration increases, the 200 poise temperature (melting temperature) generally increases. In various applications, the SiO2 concentration can be adjusted to make the melting temperature of the glass composition less than or equal to 1750°C. In various embodiments, the mol% of SiO2 can be about 64 mol% to about 71 mol%, about 66 mol% to about 71 mol%, about 68 mol% to about 71 mol%, or about 69 to about 71 mol% and all sub-ranges therebetween.

[0035] Al2O3 is another glass forming agent used in the manufacture of the glass. Higher molar percentages of Al2O3 can improve the annealing point and modulus of the glass, but increase melting and batch costs. In various embodiments, the molar percentage of Al2O3 can be from about 9% to about 12%, or from about 10% to about 12%, or from about 11% to about 12%, or from about 11% to about 11.5%, and all subranges therein.

[0036] B2O3 is a glass forming agent and flux to aid melting and lower the melting temperature. B2O3 affects the liquidus temperature and viscosity. Increasing B2O3 can increase the liquidus viscosity of the glass. To achieve this, the B2O3 concentration in one or more glass composition embodiments may be equal to or greater than 0.1 mol%; however, some compositions may contain trace amounts of B2O3. As mentioned earlier regarding SiO2, glass durability is crucial for display applications. Durability can be controlled by increasing the concentration of alkaline earth metal oxides and significantly reduced by increasing the B2O3 content. The annealing point decreases with increasing B2O3 content, so maintaining a low B2O3 content is beneficial. It has also been found that B2O3 can cause Fe to redox and transform into Fe2+. 3+ This affects blue light transmission. Therefore, in some embodiments, it has been found that reducing B2O3 can produce better optical properties. In different embodiments, the molar percentage of B2O3 can be from about 7% to about 12%, or from about 8% to about 11%, or from about 8% to about 10.5% and all subranges therein.

[0037] In addition to glass forming agents (SiO2, Al2O3, and B2O3), the glass also comprises alkaline earth metal oxides. In at least one embodiment, at least three alkaline earth metal oxides are part of the glass composition, such as MgO, CaO, BaO, and SrO. Alkaline earth metal oxides provide a variety of important properties for the glass in terms of melting, refining, forming, and end use. Therefore, to improve these aspects of glass properties, in at least one embodiment, the (MgO+CaO+SrO+BaO) / Al2O3 ratio is 1-1.25 or 1.03-1.12. As the ratio increases, the viscosity tends to drop more drastically than the liquidus temperature, making it more difficult to obtain a reasonably high T. 35k -T liq Value. In the essentially alumina-free examples, the (MgO+CaO+SrO+BaO) / Al2O3 ratio cannot be calculated (i.e., Al2O3 is zero or negligible).

[0038] In some embodiments of the invention, alkaline earth metal oxides can be considered as substantially monolithic components. This is because, compared to glass-forming oxides SiO2, Al2O3, and B2O3, alkaline earth metal oxides are qualitatively more similar to each other in their effects on viscoelasticity, liquidus temperature, and liquidus relationship. However, alkaline earth metal oxides CaO, SrO, and BaO form feldspar minerals, particularly anorthite (CaAl2Si2O8) and barium feldspar (BaAl2Si2O8), as well as strontium-containing solid solutions, but MgO does not significantly incorporate into the crystals. Therefore, when feldspar crystals are in the liquid phase, excess MgO can be used to stabilize the liquid relative to the crystals, thereby lowering the liquidus temperature. Simultaneously, the viscosity curve typically becomes steeper, the melting temperature decreases, and the effect on low-temperature viscosity is negligible.

[0039] The inventors discovered that adding a small amount of MgO can lower the melting temperature to facilitate melting, lower the liquidus temperature, and increase the liquidus viscosity to facilitate formation, while maintaining a high annealing point. In various embodiments, the glass composition comprises about 1 mol% to about 3 mol% of MgO, or about 1 mol% to about 2.5 mol%, or about 1 mol% to about 2 mol%, and all subranges therein.

[0040] Not limited to any particular operating theory, it is believed that the presence of calcium oxide in the glass composition can produce a low liquidus temperature (high liquidus viscosity), a high annealing point and modulus, and a CTE within the optimal range for display and light guide plate applications. Calcium oxide also contributes to chemical durability, and is cheaper as a batch material compared to other alkaline earth metal oxides. However, high concentrations of CaO will increase density and CTE. Additionally, at sufficiently low SiO2 concentrations, CaO can stabilize anorthite and reduce liquidus viscosity. Therefore, in one or more embodiments, the CaO concentration can be from 6 to 11.5 mol%. In different embodiments, the CaO concentration in the glass composition can be from about 7 mol% to about 11 mol%, or from about 7.4 mol% to about 10 mol%, and all sub-ranges therebetween.

[0041] Both SrO and BaO can contribute to low liquidus temperatures (high liquidus viscosities). The selection and concentration of oxides can be chosen to avoid increased CTE and density, and decreased modulus and annealing point. The relative proportions of SrO and BaO can be balanced to obtain an appropriate combination of physical properties and liquidus viscosities, allowing the glass to be formed using a downdraw process. In various embodiments, the glass contains about 0 to about 2.0 mol% SrO, or about 0 mol% to about 1.5 mol%, or about 0.1 to about 1.4 mol%, and all sub-ranges therebetween. In one or more embodiments, the glass contains about 0 to about 0.1 mol% BaO, or 0 to about 0.09 mol%, or 0 to about 0.08 mol%, and all sub-ranges therebetween. In other embodiments, the glass is substantially free of BaO.

[0042] In addition to the components described above, the glass composition may also include various other oxides to adjust the various physical, melting, clarifying, and formation properties of the glass. Examples of other oxides include, but are not limited to, TiO2, MnO, V2O3, Fe2O3, ZrO2, ZnO, Nb2O5, MoO3, Ta2O5, WO3, Y2O3, La2O3, and CeO2, as well as other rare earth metal oxides and phosphates. In some embodiments, the amount of each oxide is less than or equal to 2.0 mol%, and the total binding concentration is less than or equal to 5.0 mol%. In some embodiments, the glass composition comprises about 0 to about 4.0 mol% of ZnO, or about 0 mol% to about 3.5 mol%, or about 0 to about 3.01 mol%, or about 0 to about 2.0 mol%, and all subranges therebetween. In other embodiments, the glass composition comprises about 0.1 mol% to about 1.0 mol% of titanium oxide, about 0.1 mol% to about 1.0 mol% of vanadium oxide, about 0.1 mol% to about 1.0 mol% of niobium oxide, about 0.1 mol% to about 1.0 mol% of manganese oxide, about 0.1 mol% to about 1.0 mol% of zirconium oxide, about 0.1 mol% to about 1.0 mol% of tin oxide, about 0.1 mol% to about 1.0 mol% of molybdenum oxide, about 0.1 mol% to about 1.0 mol% of cerium oxide, and all sub-ranges of any of the above transition metal oxides. The glass composition may also include various batch-related contaminants and / or contaminants introduced into the glass by melting, refining, and / or forming equipment used in glassmaking. The glass may also contain SnO2, such as SnO2, SnO, SnCO3, SnC2O2, etc., generated by Joule melting using tin oxide electrodes and / or by tin-containing material batching.

[0043] In some embodiments, the glass composition is characterized as alkali-free glass. As used herein, "alkali-free glass" refers to glass with a total alkali metal concentration of less than or equal to 0.1 mol%, wherein the total alkali metal concentration is the sum of the concentrations of Na₂O, K₂O, and Li₂O.

[0044] In other embodiments, the ratio of alkali metal to alumina in the glass composition is less than or equal to 0.5.

[0045] In some embodiments, the glass composition has one or more of the following compositional characteristics: (i) an As2O3 concentration of up to 0.05 to 1.0 mol%; (ii) an Sb2O3 concentration of up to 0.05 to 1.0 mol%; and (iii) a SnO2 concentration of up to 0.25 to 3.0 mol%.

[0046] As₂O₃ is an effective high-temperature clarifying agent for display glass, and in some embodiments, As₂O₃ is used for clarification due to its superior clarifying properties. However, As₂O₃ is toxic and requires special handling during the glass manufacturing process. Therefore, in some embodiments, large amounts of As₂O₃ are not used for clarification, i.e., the finished glass has at most 0.05 mol% As₂O₃. In one embodiment, As₂O₃ is not intentionally used to clarify the glass. In this case, due to contaminants present in the batch and / or the equipment used to melt the batch, the finished glass typically has at most 0.005 mol% As₂O₃.

[0047] While less toxic than As₂O₃, Sb₂O₃ is still toxic and requires special handling. Furthermore, compared to glass using As₂O₃ or SnO₂ as a clarifier, Sb₂O₃ increases density, raises CTE, and lowers the annealing point. Therefore, in some embodiments, large amounts of Sb₂O₃ are not used for clarification, i.e., the finished glass contains at most 0.05 mol% Sb₂O₃. In another embodiment, Sb₂O₃ is not intentionally used to clarify the glass. In this case, due to the presence of contaminants in the batch and / or the equipment used to melt the batch, the finished glass typically contains at most 0.005 mol% Sb₂O₃.

[0048] Compared to As₂O₃ and Sb₂O₃ clarification, tin clarification (i.e., SnO₂ clarification) is less efficient, but SnO₂ is a widely used material without known harmful properties. Furthermore, SnO₂ has been a component of display glass for many years due to the use of tin oxide electrodes in Joule melting of glass batches. In the manufacture of liquid crystal displays using such glass, the presence of SnO₂ in the display glass has no known adverse effects. However, high SnO₂ concentrations are undesirable as they can create crystallization defects in the display glass. In one embodiment, the SnO₂ concentration of the finished glass is less than or equal to 0.5 mol%, from about 0.01 to about 0.5 mol%, from about 0.01 to about 0.11 mol%, from about 0.08 to about 0.15 mol%, and all sub-ranges therebetween.

[0049] Tin clarification can be used alone or in combination with other clarification techniques, depending on requirements. For example, tin clarification can be combined with halide clarification, such as bromine clarification. Other possible combinations include, but are not limited to, tin clarification combined with sulfate, sulfide, cerium oxide, mechanical bubbling, and / or vacuum clarification. It should be understood that other clarification techniques can be used alone. In some embodiments, maintaining the (MgO+CaO+SrO+BaO) / Al2O3 ratio and the concentration of individual alkaline earth metals within the above-mentioned ranges can make the clarification process easier and more effective.

[0050] In one or more embodiments, as described above, the exemplary glass may have low concentrations of elements that produce visible absorption in the glass matrix. Such absorbers include transition elements such as Ti (titanium), V (vanadium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), and Cu (copper) and rare earth elements with partially filled f-orbitals, including Ce (cerium), Pr (praseodymium), Nd (neodymium), Sm (samarium), Eu (europium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), and Tm (thulium). Fe, Cr, and Ni are the most abundant elements in conventional glass melting feedstocks. Iron is a common contaminant in sand (a SiO2 source) and a typical contaminant in aluminum, magnesium, and calcium feedstocks. Chromium and nickel are typically present in low concentrations in normal glass feedstocks, but are found in various placer deposits and must be controlled at low concentrations. In addition, chromium and nickel can be introduced through contact with stainless steel, for example, when the raw material or broken glass is crushed, the steel-lined mixer or screw feeder is corroded, or accidentally comes into contact with the structural steel of the melting unit itself. In some embodiments, the concentration of iron is specifically less than 50 ppm, more specifically less than 40 ppm or less than 25 ppm, and the concentrations of Ni and Cr are specifically less than 5 ppm, more specifically less than 2 ppm. In further embodiments, the concentrations of all other absorbents listed above are each less than 1 ppm. In various embodiments, the glass contains 1 ppm or less of Co, Ni, and Cr, or less than 1 ppm of Co, Ni, and Cr. In various embodiments, transition elements (V, Cr, Mn, Fe, Co, Ni, and Cu) may be present in the glass at 0.1% by weight or less. In some embodiments, the concentration of Fe may be <about 50 ppm, <about 40 ppm, <about 30 ppm, <about 20 ppm, or <about 10 ppm.

[0051] In other embodiments, it has been found that adding certain transition metal oxides that do not cause absorption in the 300 nm to 650 nm range and have an absorption band of <300 nm can prevent the formation of network defects and prevent color centers (e.g., 300 nm to 650 nm light absorption) after UV exposure during ink curing. This is because the transition metal oxide bonds in the glass network will absorb light without allowing light to break the base bonds of the glass network. Therefore, exemplary embodiments may include any of the following transition metal oxides or compositions to minimize UV ​​color center formation: about 0.1 mol% to about 3.0 mol% of zinc oxide, about 0.1 mol% to about 1.0 mol% of titanium oxide, about 0.1 mol% to about 1.0 mol% of vanadium oxide, about 0.1 mol% to about 1.0 mol% of niobium oxide, about 0.1 mol% to about 1.0 mol% of manganese oxide, about 0.1 mol% to about 2.0 mol% of zirconium oxide, about 0.1 mol% to about 1.0 mol% of arsenic oxide, about 0.1 mol% to about 1.0 mol% of tin oxide, about 0.1 mol% to about 1.0 mol% of molybdenum oxide, about 0.1 mol% to about 1.0 mol% of antimony oxide, about 0.1 mol% to about 1.0 mol% of cerium oxide, and all sub-ranges of any of the above transition metal oxides. In some embodiments, the exemplary glass may contain 0.1 mol% to less than or no more than about 3.0 mol% of any combination of zinc oxide, titanium oxide, vanadium oxide, niobium oxide, manganese oxide, zirconium oxide, arsenic oxide, tin oxide, molybdenum oxide, antimony oxide, and cerium oxide.

[0052] Even when the transition metal concentration is within the aforementioned range, inappropriate absorption may still occur due to matrix and redox reactions. For example, those skilled in the art know that iron in glass exists in two valence states: +3 (ferric) and +2 (ferrous). In glass, Fe... 3+ Absorption occurs at approximately 380, 420, and 435 nm, Fe 2+ Absorption occurs primarily at IR wavelengths. Therefore, according to one or more embodiments, the aim is to force as much iron as possible into the ferriferrous state to achieve high transmittance at visible wavelengths. A non-limiting method for achieving this is to add inherently reducing components to the glass batch. Such components include carbon, hydrocarbons, or certain reducing metals, such as silicon, boron, or aluminum. However, if the iron content is within the stated range, at least 10% ferriferrous iron, and more specifically greater than 20% ferriferrous iron, according to one or more embodiments, can produce improved transmittance at shorter wavelengths. Thus, in various embodiments, the iron concentration in the glass results in an attenuation of less than 1.1 dB / 500 mm in the glass sheet.

[0053] LCD panel rigidity

[0054] One property of an LCD panel is its total thickness. In traditional approaches attempting to create thin structures, insufficient rigidity has been a serious problem. However, rigidity can be improved using exemplary glass LGP, as glass has a much higher modulus of elasticity than PMMA. In some embodiments, from a rigidity perspective, for maximum benefit, all components of the panel can be joined together at the edges.

[0055] Figure 3 This is a cross-sectional view of an exemplary LCD panel with an LGP according to one or more embodiments. (Refer to...) Figure 3 An exemplary embodiment of a panel structure 500 is provided. The structure includes an LGP 100 mounted on a backplate 550, through which light can travel and be redirected toward an LCD or an observer. A structural assembly 555 attaches the LGP 100 to the backplate 550, forming a gap between the back surface of the LGP and the working surface of the backplate. A reflective and / or diffuser film 540 is disposed between the back surface of the LGP 100 and the backplate 550 to transmit regenerated light back through the LGP 100. A plurality of LEDs, organic light-emitting diodes (OLEDs), or cold cathode fluorescent lamps (CCFLs) are disposed adjacent to the light injection edge 130 of the LGP, wherein the width of the LEDs is the same as the thickness of the LGP 100 and at the same height as the LGP 100. In other embodiments, the LEDs have a width and / or height greater than the thickness of the LGP 100. Conventional LCDs may employ LEDs or CCFLs and package them with color-converting phosphors to produce white light. One or more backlight films 570 are disposed adjacent to the front surface of the LGP 100. LCD panel 580 can also be disposed above the front of LGP 100 using structural component 585, with backlight film 570 located in the gap between LGP 100 and LCD panel 580. Light from LGP 100 then passes through film 570, which can backscatter large-angle light and reflect small-angle light back to reflective film 540 for regeneration, and can concentrate the light in a forward direction (e.g., towards the user). Baffle 520 or other structural components can hold the components in place. Liquid crystal layer (not shown) can use and may contain electro-optic materials; when an electric field is applied, the liquid crystal layer structure rotates, causing any passing light to be polarized. Other optical components include, for example, prism films, polarizers, or TFT arrays. According to different embodiments, the angle filter can be coupled with a transparent light guide plate of a transparent display device. In some embodiments, LGP is bonded to a structure (using optically transparent adhesive OCA or pressure-sensitive adhesive PSA), where LGP provides some structural components of the optically contacting panel. In other words, some light may leak out of the light guide through the adhesive. Leaked light can be scattered or absorbed by structural components. As mentioned above, this problem can be avoided by properly fabricating the LED coupled to the first edge of the LGP and the two adjacent edges where the light requires TIR reflection.

[0056] The exemplary width and height of the LGP depend largely on the size of each LCD panel. It should be noted that the target embodiments of the present invention can be applied to LCD panels of any size, whether small (diagonal < 40") or large (diagonal > 40") displays. Exemplary dimensions of the LGP include, but are not limited to, diagonal 20", 30", 40", 50", 60" or more.

[0057] Figure 4 This is a cross-sectional view of an exemplary LCD panel with an LGP according to another embodiment. (Refer to...) Figure 4 Additional embodiments employ a reflective layer. In some embodiments, losses can be reduced by using metallized glass, such as silver, or by printing with reflective inks to insert a reflective surface between the LGP and the epoxy resin. In other embodiments, a high-reflectivity film (e.g., an "Enhanced Specular Reflector" film (manufactured by 3M)) may be laminated with the LGP.

[0058] Figure 5 This is a schematic diagram of an LGP with an adhesive pad according to an additional embodiment. (Refer to...) Figure 5 An adhesive pad is used instead of continuous adhesive, with pad 600 shown as a series of black squares. Therefore, to limit the surface optical connection of the LGP to the structural components, the illustrated embodiment uses 5×5 mm pads per 50 mm. 2 The pad 600 is a square pad designed to provide sufficient adhesive strength, wherein light extraction is less than 4%. Of course, the pad 600 may be circular or another polygon, and may be provided in any array or at any interval; this description should not limit the scope of the appended claims.

[0059] Color shift compensation

[0060] In prior art glasses, while reducing iron concentration can decrease absorption and yellow shift, it is difficult to completely eliminate them. The Δx and Δy values ​​for PMMA measured at a propagation distance of approximately 700 mm are 0.0021 and 0.0063, respectively. In exemplary glasses with the stated composition range, the color shift Δy is <0.015, and in exemplary embodiments, it is less than 0.0021 and less than 0.0063. For example, in some embodiments, the color shift was measured as 0.007842, and in other embodiments, it was measured as 0.005827. In other embodiments, the exemplary glass sheet may contain a color shift Δy of less than 0.015, for example, from about 0.001 to about 0.015 (e.g., about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.011, 0.012, 0.013, 0.014, or 0.015). In other embodiments, the transparent substrate may contain a color shift of less than 0.008, less than about 0.005, or less than about 0.003. The color shift can be characterized using the CIE 1931 standard for color measurement, measuring the variation of the x and / or y color coordinates along a length L for a given light source illumination. For an exemplary glass light guide plate, the color shift Δy can be expressed as Δy = y(L2) - y(L1), where L2 and L1 are the Z positions away from the source emission (e.g., LED or others) along the panel or substrate direction, and L2 - L1 = 0.5 meters. The exemplary light guide plate has Δy < 0.015, Δy < 0.005, Δy < 0.003, or Δy < 0.001. The color shift of the light guide plate can be evaluated by measuring the optical absorption of the light guide plate, calculating the internal transmission of the LGP across 0.5 m using the optical absorption, and then multiplying the resulting transmission curve by a typical LED light source used for LCD backlighting, such as the Nichia NFSW157D-E. The (X, Y, Z) tri-values ​​of the spectrum are then calculated using the CIE color matching function. The values ​​are then normalized by a numerical sum to provide (x, y) color coordinates. The difference between the (x, y) value of the LED spectrum multiplied by the 0.5-meter LGP transmittance and the (x, y) value of the original LED spectrum is an estimate of the color shift contribution of the light guide material. Several exemplary solutions can be implemented to address residual color shift. In one embodiment, a blue paint is used on the light guide. By painting the light guide blue, red and green absorption can be artificially increased, and blue light extraction can be increased. Therefore, knowing how much difference in color absorption exists, the blue paint pattern can be calculated backward to compensate for the color shift. In one or more embodiments, a shallow surface scattering feature structure is used to extract light, where efficiency depends on wavelength. For example, a square grating has maximum efficiency when the optical path difference is equal to half the wavelength. Therefore, exemplary textures can be used to preferentially extract blue and incorporate a primary light extraction texture. In additional embodiments, image processing can also be employed. For example, an image filter can be applied to attenuate blue near the light injection edge.This requires shifting the color of the LED itself to maintain pure white. In a further embodiment, the pixel geometry can be used to adjust the RGB pixel surface area ratio of the panel and increase the surface area of ​​the blue pixels away from the light injection edge to resolve color shift.

[0061] The aforementioned exemplary composition can therefore be used to achieve strain points above or equal to about 650°C, about 650°C to about 700°C, or about 650°C to about 680°C and all sub-ranges therein. The density of the exemplary glass composition can be about 2.34 g / cc @ 20°C to about 2.56 g / cc @ 20°C, or about 2.35 g / cc @ 20°C to about 2.55 g / cc @ 20°C and all sub-ranges therein.

[0062] Certain embodiments and compositions provide internal transmittance greater than 90%, greater than 91%, greater than 92%, greater than 93%, greater than 94%, and even greater than 95% in the 400-700 nm range. Internal transmittance can be measured by comparing the light penetrating the sample with the light emitted from the light source. Broadband incoherent light can be cylindrically focused to the end of the test material. Far-side emitted light can be collected using the integrating sphere fiber of a coupled spectrometer to form sample data. Reference data is obtained by removing the test material from the system, translating the integrating sphere directly in front of the focusing optics, and collecting light passing through the same device as reference data. Absorbance at a given wavelength is expressed as:

[0063]

[0064] The internal transmittance when crossing 0.5 meters is expressed as:

[0065] .

[0066] Therefore, the internal transmittance of the exemplary embodiment at 450 nm and a length of 500 mm is greater than 85%, greater than 90%, greater than 91%, greater than 92%, greater than 93%, greater than 94%, and even greater than 95%. The internal transmittance of the exemplary embodiment at 550 nm and a length of 500 mm is also greater than 90%, greater than 91%, greater than 92%, greater than 93%, greater than 94%, and even greater than 96%. The further embodiment at 630 nm and a length of 500 mm has a transmittance greater than 85%, greater than 90%, greater than 91%, greater than 92%, greater than 93%, greater than 94%, and even greater than 95%.

[0067] In one or more embodiments, the LGP has a width of at least about 1270 mm and a thickness of about 0.5 mm to about 3.0 mm, wherein the LGP has a transmittance of at least 80% per 500 mm. In different embodiments, the LGP has a thickness of about 1 mm to about 8 mm and a plate width of about 1100 mm to about 1300 mm.

[0068] Example

[0069] The following examples illustrate the methods and results according to the objectives of the disclosed invention. These examples are not intended to include all embodiments of the objectives described herein, but rather to illustrate representative methods and results. The examples are not intended to exclude equivalents and variations of the invention, as will be apparent to those skilled in the art.

[0070] While efforts have been made to ensure the accuracy of figures (e.g., quantities, temperatures, etc.), some errors and biases should still be accounted for. Unless otherwise specified, temperature is in °C or ambient temperature, and pressure is in atmosphere or near-atmosphere. The composition itself is based on oxide molar percentages and normalized to 100%. Many variations and combinations of reaction conditions, such as component concentrations, temperature, pressure, and other reaction ranges and conditions, are possible to optimize the process for product purity and yield. Optimization of these process conditions requires only reasonable routine experiments.

[0071] The glass properties listed in Table 1 below were determined using conventional techniques in the glass industry. The values ​​are expressed as the linear coefficient of thermal expansion (CTE) over a temperature range of 25°C–300°C, expressed as ×10⁻¹⁰. -7 / ℃ is used to express the annealing point, which is expressed in ℃. These are determined by fiber elongation techniques (according to ASTM references E228-85 and C336, respectively). Density is expressed in grams per cubic centimeter and measured using the Archimedes method (ASTM C693). Melting temperature is expressed in ℃ (defined as the temperature at which the glass melt exhibits a viscosity of 200 poise) and calculated by fitting high-temperature viscosity data measured by a rotating cylindrical viscometer using the Fulcher equation (ASTM C965-81).

[0072] The liquidus temperature of the glass is expressed in °C and measured using the standard gradient boat liquidus method of ASTM C829-81. This involves placing shards of glass into a platinum boat, placing the boat in a furnace with a gradient temperature zone, heating the boat in the appropriate temperature zone for 24 hours, and using microscopy to determine the highest temperature at which crystals appear inside the glass. More specifically, the entire glass sample is removed from the Pt (platinum) boat and examined using a polarized light microscope to identify the location and nature of crystals formed at the Pt-air interface and inside the sample. Because the furnace gradient is well known, the temperature-to-position relationship can be reasonably estimated within 5-10 °C. The temperature at which crystals are observed inside the sample is measured to represent the liquidus of the glass (corresponding to the test time). To observe slow-growing phases, the test may sometimes be performed for a longer period (e.g., 72 hours). The liquidus viscosity (poise) is determined by the liquidus temperature and a coefficient of the Fulcher equation. If present, the Young's modulus is expressed in gigapascals (GPa) and determined using the general-purpose resonant ultrasonic spectroscopy technique described in ASTM E1875-00e1.

[0073] The exemplary glass in the table was prepared using commercially available sand as the silica source and ground to pass through a standard US 100 sieve at a weight of 90% by weight. Alumina was the alumina source, periclase was the MgO source, limestone was the CaO source, strontium carbonate, strontium nitrate, or a mixture thereof was the SrO source, barium carbonate was the BaO source, and tin(IV) oxide was the SnO source. 2 Source. The raw materials are thoroughly mixed, placed in a platinum container suspended in a furnace, and heated by a silicon carbide incandescent rod. Melting and stirring are carried out at 1600°C to 1650°C for several hours to ensure homogeneity, and the mixture is then conveyed through an orifice at the bottom of the platinum container. The resulting glass discs are annealed to their annealing point or near-annealing point, and then subjected to various experimental methods to determine their physical, viscosity, and liquid phase properties.

[0074] The glass in the table can be prepared using standard methods familiar to skilled technicians. These methods include continuous melting processes, such as continuous melting processes where the melter used is heated by gas, electricity, or a combination thereof.

[0075] Suitable raw materials for manufacturing exemplary glasses include commercially available sand as a source of SiO2; bauxite, aluminum hydroxide, hydrated alumina, and various aluminosilicates, nitrates, and halides as a source of Al2O3; boric acid, anhydrous boric acid, and boron oxide as a source of B2O3; periclase, dolomite (also a source of CaO), magnesium oxide, magnesium carbonate, magnesium hydroxide, and various forms of magnesium silicate, aluminosilicates, nitrates, and halides as a source of MgO; limestone, aragonite, dolomite (also a source of MgO), wollastonite, and various forms of calcium silicate, aluminosilicates, nitrates, and halides as a source of CaO; and oxides, carbonates, nitrates, and halides of strontium and barium. If a chemical clarifying agent is required, tin may be added from SnO2, a mixed oxide with another major glass component (e.g., CaSnO3), or under oxidizing conditions from SnO, tin oxalate, tin halides, or other tin compounds known to a skilled craftsman.

[0076] The glass in the table may contain SnO2 as a clarifying agent, but other chemical clarifying agents may also be used to obtain glass of sufficient quality for display applications. For example, exemplary glass may intentionally incorporate any or a combination of As2O3, Sb2O3, CeO2, Fe2O3, and halides to aid in clarification, and any of these may be used in conjunction with the SnO2 chemical clarifying agent described in the examples. Of course, As2O3 and Sb2O3 are generally considered hazardous materials and need to be controlled in waste streams generated during glass manufacturing or TFT panel processing. Therefore, the individual or combined concentration of As2O3 and Sb2O3 is limited to no more than 0.005 mol%.

[0077] Aside from elements intentionally incorporated into exemplary glasses, almost all stable elements in the periodic table can exist in glass to some extent, whether through minor contamination of raw materials, high-temperature corrosion of refractory materials and precious metals during manufacturing, or intentional introduction in small amounts to fine-tune the properties of the final glass. For example, zirconium can be introduced as a contaminant through interaction with zirconium-rich refractory materials. Platinum and rhodium, for instance, can be introduced through interaction with precious metals. Iron can be introduced into raw materials as an impurity or intentionally added to enhance control of gaseous inclusions. Manganese can be introduced to control color or enhance control of gaseous inclusions.

[0078] Hydrogen inevitably exists in the form of hydroxide anions (OH-), the presence of which can be determined by standard infrared spectroscopy. The dissolution of hydroxide ions has a significantly nonlinear effect on the annealing point of the exemplary glass; therefore, to obtain the desired annealing point, the concentration of the main oxide component must be adjusted to compensate. The hydroxide ion concentration can be controlled to some extent by selecting the raw materials or the melting system. For example, boric acid is a major source of hydroxide, and replacing boric acid with boron oxide is a useful means of controlling the hydroxide concentration in the final glass. The same argument applies to other feasible raw materials containing hydroxide ions, hydrates, or compounds containing physically or chemically adsorbed water molecules. If a burner is used in the melting process, hydroxide ions can also be introduced through combustion products from the combustion of natural gas and related hydrocarbons; therefore, it is desirable to transfer the energy used for melting from the burner to the electrodes to compensate. Alternatively, a process of iteratively adjusting the main oxide component can be used to compensate for the detrimental effects of hydroxide ion dissolution.

[0079] Sulfur is commonly found in natural gas and is also an influencing component of many carbonate, nitrate, halide, and oxide feedstocks. In its SO2 form, sulfur is a troublesome source of gaseous inclusions. The tendency to form SO2-rich defects can be effectively managed by controlling the sulfur content in the feedstock and incorporating small amounts of relatively reduced polyvalent cations into the glass matrix. Although not intended to be theoretically limited, SO2-rich gaseous inclusions are primarily generated by the reduction of sulfates (SO4=) dissolved in the glass. A high barium concentration in an exemplary glass would appear to increase sulfur retention in the glass during the early melting stages, but as mentioned above, achieving a low liquidus temperature and high To is preferable. 35k -T liq Barium is required for high liquid phase viscosity. Intentionally controlling the amount of sulfur in the raw materials is a useful means of reducing dissolved sulfur (presumably sulfate) in the glass. Specifically, the sulfur content in the batch is preferably less than 200 ppm by weight, and more preferably less than 100 ppm by weight.

[0080] The reduction of polyvalent elements can also be used to control the tendency of exemplary glasses to form SO2 bubbles. Although not intended to be limited to theory, the element acts as a potential electron donor, suppressing the electromotive force of sulfate reduction. Sulfate reduction can be represented by a half-reaction, for example, SO4⁻ → SO₂ + O₂ + 2e⁻, where e⁻ represents an electron. The “equilibrium constant” of the half-reaction is Keq = [SO₂][O₂][e⁻] 2 / [SO4=], where brackets indicate chemical reactivity. Ideally, a forced reaction is desired to produce sulfate from SO2, O2, and 2e-. Adding nitrates, peroxides, or other oxygen-rich feedstocks may be helpful, but they can also hinder sulfate reduction in the early melting stages, negating any initial benefits. SO2 has low solubility in most glasses, making its addition to the glass melting process impractical. Electrons can be "added" through the reduction of polyvalents. For example, ferrous (Fe) 2+ The appropriate electron-donating half-reaction of 2Fe can be represented as 2Fe2+ →2Fe 3+ +2e-.

[0081] The "reactivity" of electrons forces the sulfate reduction reaction to the left, making SO4= stable in the glass. This is suitable for reducing polyvalent sulfates, including but not limited to Fe. 2+ Mn 2+ Sn 2+ Sb 3+ As 3+ V 3+ Ti 3+ And other reduced polyvalents familiar to skilled technicians. In each case, it is important to minimize the concentration of these components to avoid adverse effects on the glass color, or in the case of As and Sb, it is advisable to avoid adding too much of these components, which would complicate waste management in the end-user's process.

[0082] In addition to the main oxide components and trace or mixed components of the exemplary glass described above, varying amounts of halides may be present, whether contaminants introduced through raw material selection or intentional components used to eliminate gaseous inclusions in the glass. As a clarifying agent, the amount of halide added may be about 0.4 mol% or less; however, it is generally advisable to use as little as possible to avoid corrosion of exhaust treatment equipment. In some embodiments, the concentration of individual halide elements is less than about 200 ppm by weight of each halide, or less than about 800 ppm by weight of all halide elements.

[0083] In addition to the main oxide component, trace and mixed components, and polyvalent and halide clarifying agents, it is beneficial to incorporate low concentrations of other colorless oxide components to achieve desired physical, solar, optical, or viscoelastic properties. Such oxides include, but are not limited to, TiO2, ZrO2, HfO2, Nb2O5, Ta2O5, MoO3, WO3, ZnO, In2O3, Ga2O3, Bi2O3, GeO2, PbO, SeO3, TeO2, Y2O3, La2O3, Gd2O3, and other oxides known to those skilled in the art. By adjusting the relative proportions of the main oxide components in the exemplary glass, the annealing point, T... 35k -T liqIn cases involving liquid phase viscosity, up to about 2 mol% to 3 mol% of a colorless oxide may be added. For example, some embodiments may include any or a combination of the following transition metal oxides to minimize UV ​​color center formation: about 0.1 mol% to about 3.0 mol% of zinc oxide, about 0.1 mol% to about 1.0 mol% of titanium oxide, about 0.1 mol% to about 1.0 mol% of vanadium oxide, about 0.1 mol% to about 1.0 mol% of niobium oxide, about 0.1 mol% to about 1.0 mol% of manganese oxide, about 0.1 mol% to about 2.0 mol% of zirconium oxide, about 0.1 mol% to about 1.0 mol% of arsenic oxide, about 0.1 mol% to about 1.0 mol% of tin oxide, about 0.1 mol% to about 1.0 mol% of molybdenum oxide, about 0.1 mol% to about 1.0 mol% of antimony oxide, about 0.1 mol% to about 1.0 mol% of cerium oxide, and all sub-ranges of any of the above transition metal oxides. In some embodiments, the exemplary glass may contain 0.1 mol% to less than or no more than about 3.0 mol% of any combination of zinc oxide, titanium oxide, vanadium oxide, niobium oxide, manganese oxide, zirconium oxide, arsenic oxide, tin oxide, molybdenum oxide, antimony oxide, and cerium oxide.

[0084] Table 1 lists examples of the highly transparent glass described above.

[0085] Table 1

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093] Figure 6 This is a graph showing the percentage of transmission at a wavelength (nm) over a 500 mm path, based on some embodiments in Table 1 above. (Refer to...) Figure 6Example 13 shows a composition with a transmittance of 90.32% at 450 nm, 94.70% at 550 nm, and 93.03% at 630 nm, with a color shift of 0.006156. Example 31 shows a composition with a transmittance of 89.55% at 450 nm, 94.25% at 550 nm, and 92.36% at 630 nm, with a color shift of 0.006646. Example 43 shows a composition with a transmittance of 90.00% at 450 nm, 94.34% at 550 nm, and 92.25% at 630 nm, with a color shift of 0.006027. Example 47 shows a composition with a transmittance of 89.74% at 450 nm, 94.43% at 550 nm, and 92.99% at 630 nm, with a color shift of 0.006737. Variation (43') of Example 43 exhibits a transmittance of 89.98% at 450 nm, 93.89% at 550 nm, and 90.66% at 630 nm, with a color shift of 0.005296. Variation (13') of Example 13 exhibits a transmittance of 88.82% at 450 nm, 93.47% at 550 nm, and 91.85% at 630 nm, with a color shift of 0.0064.

[0094] As shown in the table above, in some embodiments, an exemplary glass article comprises a glass sheet having a front side having a width and a height, a back side facing the front side, and a thickness between the front and back sides, and forming four edges surrounding the front and back sides, wherein the glass sheet is substantially free of alkali metals and contains about 64 mol% to about 71 mol% of SiO2, about 9 mol% to about 12 mol% of Al2O3, about 7 mol% to about 12 mol% of B2O3, about 1 mol% to about 3 mol% of MgO, about 6 mol% to about 11.5 mol% of CaO, about 0 mol% to about 2 mol% of SrO, about 0 mol% to about 0.1 mol% of BaO, about 0.01 mol% to about 0.5 mol% of SnO2, less than 1 ppm of each of Co, Ni and Cr, and less than about 50 ppm of Fe.

[0095] In other embodiments, an exemplary glass article comprises a glass sheet having a front side having a width and a height, a back side facing the front side, and a thickness between the front side and the back side, and forming four edges surrounding the front side and the back side, wherein the glass sheet comprises about 64 mol% to about 71 mol% of SiO2, about 9 mol% to about 12 mol% of Al2O3, about 7 mol% to about 12 mol% of B2O3, about 1 mol% to about 3 mol% of MgO, about 6 mol% to about 11.5 mol% of CaO, about 0 mol% to about 2 mol% of SrO, about 0 mol% to about 0.1 mol% of BaO, about 0.01 mol% to about 0.5 mol% of SnO2, less than 0.5 mol% of any one or a combination of Na2O, K2O, and Li2O, less than 1 ppm of each of Co, Ni, and Cr, and less than about 50 ppm of Fe.

[0096] In other embodiments, an exemplary glass article comprises a glass sheet having a front side having a width and a height, a back side facing the front side, and a thickness between the front and back sides, and forming four edges surrounding the front and back sides, wherein the glass sheet comprises about 64 mol% to about 71 mol% of SiO2, about 9 mol% to about 12 mol% of Al2O3, about 7 mol% to about 12 mol% of B2O3, about 1 mol% to about 3 mol% of MgO, about 6 mol% to about 11.5 mol% of CaO, about 0 mol% to about 2 mol% of SrO, about 0 mol% to about 0.1 mol% of BaO, about 0.01 mol% to about 0.5 mol% of SnO2, an alkali metal to Al2O3 ratio of less than or equal to 0.5, less than 1 ppm of Co, Ni and Cr, and less than about 50 ppm of Fe.

[0097] Any of the above embodiments may have a color shift of <0.008 or <0.005. In other embodiments, the Fe concentration is <about 20 ppm or <about 10 ppm. In some embodiments, the strain temperature of the glass is about 650°C to 750°C. In some embodiments, the CTE of the glass is about 29 to 36. In some embodiments, the density of the glass is about 2.34 g / cm³@20°C to about 2.56 g / cm³@20°C. In some embodiments, each glass article is a light guide plate with a thickness of about 0.2 mm to about 8 mm. The light guide plate may be manufactured by a fusion drawing process, a slot drawing process, or a float glass process. In some embodiments, the glass contains less than 1 ppm each of Co, Ni, and Cr. In some embodiments, the transmittance is greater than or equal to 85% at 450 nm and at least 500 mm in length, greater than or equal to 90% at 550 nm and at least 500 mm in length, greater than or equal to 85% at 630 nm and at least 500 mm in length, and the above-described compositions. In some embodiments, the glass comprises 0.1 mol% to no more than about 3.0 mol% of any one or a combination of ZnO, TiO2, V2O3, Nb2O5, MnO, ZrO2, As2O3, SnO2, MoO3, Sb2O3 and CeO2.

[0098] It should be understood that the different embodiments described may involve specific features, structures, components, or steps described in particular embodiments. It should also be understood that while specific features, structures, components, or steps are described in particular embodiments, they may be interchanged or combined with alternative embodiments in various unshown combinations or arrangements.

[0099] It should also be understood that, unless explicitly stated otherwise, the terms “the” or “a” as used herein mean “at least one” and should not be limited to “only one.” Thus, for example, unless explicitly stated otherwise, the designation “a ring” includes instances of two or more rings. Similarly, “multiple” or “array” is intended to mean “more than one.” Thus, “multiple droplets” includes two or more droplets, such as three or more droplets, and “an array of rings” includes two or more droplets, such as three or more rings.

[0100] A range here is expressed as from “about” a specific value and / or to “about” another specific value. When a range is expressed in this way, instances will include from one specific value and / or to another specific value. Similarly, when a numerical value is expressed as an approximation with the antecedent “about”, it is understood that the specific value constitutes another aspect. It should also be understood that the endpoints of each range are valid relative to and independent of the other endpoint.

[0101] As used herein, the terms "basically," "essentially," and variants are intended to mean that the described feature is equal to or nearly equal to a certain value or description. For example, the term "basically planar" refers to a planar or nearly planar surface. Furthermore, as defined above, "basically similar" refers to two values ​​being equal to or nearly equal. In some embodiments, "basically similar" means that the values ​​differ from each other by less than about 10%, for example, less than about 5% or less than about 2%.

[0102] Unless explicitly stated otherwise, any method mentioned herein is not intended to be construed as requiring the steps to be performed in a particular order. Therefore, no particular order is to be inferred when the method claim does not actually describe a sequence of steps, or when the claims or embodiments do not specifically indicate that the steps are limited to a particular order.

[0103] Although various features, structures, components, or steps of a particular embodiment are described using the term "comprising," it should be understood that alternative embodiments described using terms such as "consisting of" or "essentially composed of" are also included. Thus, for example, an alternative device embodiment comprising A+B+C implies both an embodiment in which the device is composed of A+B+C and an embodiment in which the device is essentially composed of A+B+C.

[0104] Those skilled in the art will understand that various modifications and refinements can be made to the invention without departing from its spirit and scope. Since those skilled in the art can incorporate the spirit and essence of the invention to obtain modifications, combinations, sub-combinations, and variations of the described embodiments, the invention should be construed as including all contents and equivalents falling within the appended claims.

Claims

1. A glass article comprising: A glass sheet having a front side with width and height, a back side facing the front side, and a thickness between the front side and the back side, and having four edge faces surrounding the front side and the back side. The glass slide is substantially free of alkali metals and contains: 64 mol% to 71 mol% SiO2; 9 mol% to 12 mol% of Al2O3; 9.74 mol% to 12 mol% of B2O3; 1 mol% to 3 mol% MgO; 6 mol% to 11.5 mol% CaO; 0 mol% to 2 mol% SrO; 0 mol% to 0.1 mol% BaO; 0.01 mol% to 0.5 mol% SnO2; Co, Ni and Cr, each less than 1 ppm; and Fe less than 50 ppm, At least 10% of the Fe is in the ferrous state. The glass plate described therein has a color shift of less than 0.

008.

2. A glass article comprising: A glass sheet having a front side with width and height, a back side facing the front side, and a thickness between the front side and the back side, and having four edge faces surrounding the front side and the back side. The glass sheet comprises: 64 mol% to 71 mol% SiO2; 9 mol% to 12 mol% of Al2O3; 9.74 mol% to 12 mol% of B2O3; 1 mol% to 3 mol% MgO; 6 mol% to 11.5 mol% CaO; 0 mol% to 2 mol% SrO; 0 mol% to 0.1 mol% BaO; 0.01 mol% to 0.5 mol% SnO2; Less than 0.5 mol% of any one or a combination of Na₂O, K₂O, and Li₂O; Co, Ni and Cr, each less than 1 ppm; and Fe less than 50 ppm, At least 10% of the Fe is in the ferrous state. The glass plate described therein has a color shift of less than 0.

008.

3. A glass article comprising: A glass sheet having a front side with width and height, a back side facing the front side, and a thickness between the front side and the back side, and having four edge faces surrounding the front side and the back side. The glass sheet comprises: 64 mol% to 71 mol% SiO2; 9 mol% to 12 mol% of Al2O3; 9.74 mol% to 12 mol% of B2O3; 1 mol% to 3 mol% MgO; 6 mol% to 11.5 mol% CaO; 0 mol% to 2 mol% SrO; 0 mol% to 0.1 mol% BaO; 0.01 mol% to 0.5 mol% SnO2; The ratio of alkali metal to Al2O3 is less than or equal to 0.5; Co, Ni and Cr, each less than 1 ppm; and Fe less than 50 ppm, At least 10% of the Fe is in the ferrous state. The glass plate described therein has a color shift of less than 0.

008.

4. The glass article according to any one of claims 1 to 3, wherein the glass has a color shift of less than 0.

005.

5. The glass article according to any one of claims 1 to 3, wherein the concentration of Fe is less than 20 ppm.

6. The glass article according to any one of claims 1 to 3, wherein the glass has a strain temperature of 650°C to 750°C.

7. The glass article according to any one of claims 1 to 3, wherein the glass has a coefficient of thermal expansion (CTE) of 29-36.

8. The glass article according to any one of claims 1 to 3, wherein the glass has a density of 2.34 g / cm³ to 2.56 g / cm³ at 20°C.

9. The glass article according to any one of claims 1 to 3, wherein the glass article is a light guide plate.

10. The glass article according to claim 9, wherein the thickness of the plate is in the range of 0.2 mm to 8 mm.

11. The glass article according to claim 9, wherein the light guide plate is manufactured by a fusion drawing process, a slot drawing process, or a float glass process.

12. The glass article according to any one of claims 1 to 3, wherein the light transmittance at 450 nm and a transmission length of at least 500 mm is greater than or equal to 85%, the light transmittance at 550 nm and a transmission length of at least 500 mm is greater than or equal to 90%, the light transmittance at 630 nm and a transmission length of at least 500 mm is greater than or equal to 85%, and combinations thereof.

13. The glass article according to any one of claims 1 to 3, wherein the glass comprises 0.1 mol% to 3.0 mol% of any one or a combination of ZnO, TiO2, V2O3, Nb2O5, MnO, ZrO2, As2O3, MoO3, Sb2O3 and CeO2.

14. The glass article according to any one of claims 1 to 3, wherein the concentration of Fe is less than 10 ppm.

15. The glass article according to any one of claims 1 to 3, wherein at least 20% of the Fe is in the ferrous state.

16. A backlight unit, comprising: A light guide plate, the light guide plate including a front side and a back side facing the front side, the light guide plate comprising a glass sheet, the glass sheet having a composition comprising the following: 64 mol% to 71 mol% SiO2; 9 mol% to 12 mol% of Al2O3; 9.74 mol% to 12 mol% of B2O3; 1 mol% to 3 mol% MgO; 6 mol% to 11.5 mol% CaO; 0 mol% to 2 mol% SrO; 0 mol% to 0.1 mol% BaO; SnO2, ranging from 0.01 mol% to 0.5 mol%, Less than 0.5 mol% of any one or a combination of Na₂O, K₂O, and Li₂O. Co, Ni and Cr, each less than 1 ppm; and Fe less than 50 ppm, A light source, facing the glass sheet, is configured to emit light toward the glass sheet. At least 10% of the Fe is in the ferrous state. The glass plate described therein has a color shift of less than 0.

008.

17. The backlight unit of claim 16, wherein the light source comprises a plurality of LEDs, OLEDs or cold cathode fluorescent lamps disposed adjacent to the light injection edge of the light guide plate and located between the front and the back.

18. The backlight unit according to claim 17, further comprising: A reflective film facing the back side of the light guide plate; and One or more optical films, The light guide plate is disposed between the one or more optical films and the reflective film.

19. A method for manufacturing a glass slide, comprising: Melt the batch to form a glass melt; and A glass sheet is formed from the molten glass using a fusion drawing process, the glass sheet having a thickness of 0.2 mm to 8 mm between its front side and the back side facing the front side. The glass sheet is composed of: 64 mol% to 71 mol% SiO2; 9 mol% to 12 mol% of Al2O3; 9.74 mol% to 12 mol% of B2O3; 1 mol% to 3 mol% MgO; 6 mol% to 11.5 mol% CaO; 0 mol% to 2 mol% SrO; 0 mol% to 0.1 mol% BaO; SnO2, ranging from 0.01 mol% to 0.5 mol%, Less than 0.5 mol% of any one or a combination of Na₂O, K₂O, and Li₂O. Co, Ni and Cr, each less than 1 ppm; and Fe less than 50 ppm, At least 10% of the Fe is in the ferrous state. The glass plate described therein has a color shift of less than 0.

008.

20. The method of claim 19, wherein the batch comprises an inherently reducing component.

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