MANUFACTURE

[0001] This application claims the benefit of priority to U.S. Provisional Application 6/051665 filed September 17, 2014 the content of which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] High-performance display devices, such as liquid crystal displays (LCDs) and plasma displays, are commonly used in various electronics, such as cell phones, laptops, electronic tablets, televisions, and computer monitors. Currently marketed display devices can employ one or more high-precision glass sheets, for example as substrates for electronic circuit components, or as color filters, to name a few applications.

[0003] LCDs are one of the most common types of flat panel displays currently in use and typically include two flat display panels provided with field generating electrodes such as a pixel electrode and a common electrode, and an intermediate liquid crystal layer. The LCD generates an electric field extending through the liquid crystal layer by applying a corresponding voltage across the field generating electrodes. This determines the orientation direction of liquid crystal molecules of the liquid crystal layer and controls polarization of incident light passing through the liquid crystal, thus displaying a desired image. LCDs are often used as a display device in a television receiver, and as market trends have led to an increased display size, there is a growing problem in that a difference in views is experienced between the case where a viewer is disposed head-on with the center of a display and the case where the viewer is disposed to watch from a left or right sides of a display.

[0004] One solution is to use curved rather than flat panel LCDs. A curved display device may be formed by curving the display device in a concave or convex manner to compensate the difference between views. The display device may be a portrait type where a vertical height is larger than a horizontal width length and a monitor is bent about a vertical axis, or a landscape type where a vertical height is smaller than a horizontal width and a monitor is bent about a horizontal axis.

[0005] When display devices panels are bent or curved, however, light leakage may result in a visible artifact to a user. This bending may occur in various situations such as, but not limited to, a curved display where LCD panels are intentionally bent to form a curved surface, and where the bend results from polarizer lamination, e.g., panels are bent unintentionally due to tension imbalance between front and the rear polarizer assembly lamination. Whether intentionally or unintentionally, such a bend or curve can cause stress retardation in the LCD substrate glasses whose birefringence optically couples with the liquid crystal leading to light leakage in the display device. Thus, there is a need in the industry to solve light leakage problems in bent or curved display devices.

SUMMARY

[0006] Some embodiments of the disclosure provide a method for

manufacturing a liquid crystal display device. The method can include the steps of providing a first panel of glass and a second panel of glass with an intermediate liquid crystal layer, dispensing an adhesive on adjacent facing surfaces of the first and second panels along a periphery of said surfaces, curing the adhesive on a first portion of the periphery to form an assembly, curving the assembly about a predetermined axis, and curing the adhesive on a second portion of the periphery.

[0007] Other embodiments include a method for manufacturing a liquid crystal display device comprising the steps of providing a first panel of glass and a second panel of glass with an intermediate liquid crystal layer, dispensing an adhesive on adjacent facing surfaces of the first and second panels along a periphery of said surfaces, curing the adhesive on a first portion of the periphery to form an assembly, partially curing the adhesive on a second portion of the periphery, curving the assembly about a predetermined axis, and completely curing the adhesive on the second portion of the periphery.

[0008] Additional embodiments include a method for manufacturing a liquid crystal display device comprising the steps of providing a first panel of glass and a second panel of glass with an intermediate liquid crystal layer, dispensing a first adhesive on adjacent facing surfaces of the first and second panels along a first portion of a periphery of said surfaces, dispensing a second adhesive on the adjacent facing surfaces of the first and second panels along a second portion of a periphery of said surfaces, curing one or both the first and second adhesives to form an assembly, and curving the assembly about a predetermined axis.

[0009] Further embodiments include a method for manufacturing a liquid crystal display device comprising the steps of providing a first panel of glass and a second panel of glass with an intermediate liquid crystal layer, dispensing an adhesive on adjacent facing surfaces of the first and second panels along a periphery of said surfaces, curing the adhesive on a first portion of the periphery to form an assembly, curving the assembly about a predetermined axis; and curing the adhesive on a second portion of the periphery in a pattern determined as a function of stress on the second portion.

[0010] Some embodiments include a method for manufacturing a liquid crystal display device comprising the steps of providing a first panel of glass and a second panel of glass with an intermediate liquid crystal layer, dispensing an adhesive on adjacent facing surfaces of the first and second panels along a periphery of said surfaces, selectively curing the adhesive, and curving the assembly about a predetermined axis.

[0011] Additional features and advantages of the disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the methods as described herein, including the detailed description which follows, the claims, as well as the appended drawings. [0012] It is to be understood that both the foregoing general description and the following detailed description present various embodiments of the disclosure, and are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to provide a further

understanding of the disclosure, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure and together with the description serve to explain the principles and operations of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The following detailed description can be best understood when read in conjunction with the following drawings, where like structures are indicated with like reference numerals where possible and in which:

[0014] FIG. 1 is a perspective view of a curved display device according to an exemplary embodiment;

[0015] FIG. 2 is a cross-sectional view of the curved display device of FIG. 1 ;

[0016] FIG. 3 is a schematic illustration showing the operation principles of an In-Plane Switching (IPS) mode;

[0017] FIG. 4 is a photographic illustration of light leakage in an IPS panel under three-point bending;

[0018] FIG. 5 is an illustration of the bending of an exemplary panel about an axis;

[0019] FIG. 6 is a simplified depiction of a lamination process of an exemplary polarizer;

[0020] FIG. 7 is a block diagram illustrating a process according to some embodiments;

[0021] FIG. 8 is a block diagram illustrating another process according to some embodiments; [0022] FIG. 9 is a block diagram illustrating a process according to further embodiments;

[0023] FIG. 10 is a block diagram illustrating a process according to additional embodiments;

[0024] FIGS. 1 1 and 12 are simplified depictions of some embodiments;

[0025] FIG. 13 is a light leakage map of an original panel under curve;

[0026] FIG. 14 is a light leakage map of an exemplary panel with left and right sides adhesive portions removed; and

[0027] FIG. 15 is a light leakage map of an exemplary panel with top and bottom sides adhesive portions removed.

DETAILED DESCRIPTION

[0028] Disclosed herein are methods and systems for manufacturing an exemplary LCD panel where stress responsible for light leakage can be eliminated by means of the panel bonding process. Exemplary embodiments can thus mitigate any necessity for glass composition alteration and can mitigate or eliminate any risk of loss in TFT and CFA glass registration.

[0029] FIG. 1 is a perspective view of a curved display device according to an exemplary embodiment. FIG. 2 is a cross-sectional view of the curved display device of FIG. 1 taken through line A-A. With reference to FIGS. 1 and 2, a curved display device according to some embodiments can include a display unit 100 including a first substrate 1 10 and a spaced apart second substrate 120 facing the first substrate 1 10 and a liquid crystal layer 130 positioned between the first and second substrates 1 10, 120. An edge ringing sealant 140 can be provided along the edges of the first substrate 1 10 and the second substrate 120 to seal the liquid crystal material in the interior of the display unit 100. The first substrate 1 10 and the second substrate 120 can be bonded to each other by the sealant 140 thereby forming a cavity containing the liquid crystal layer 130 between the substrates 1 10, 120. An exemplary curved display device may also include one or more fixing members (not shown) configured to fix the shapes of the substrates 1 10, 120 to have a predetermined curvature relative to a predetermined axis of curvature. In some embodiments the width of the cross section of the sealant 140 may be about 2.00 mm or less.

[0030] As shown in FIGS. 1 and 2, the first substrate 1 10 and second substrate 120 of the curved display device 100 can be bent or curved to have a predetermined circular curvature relative to a common central vertical or horizontal axis. It should be noted that the terms bent, curved and variations thereof are used interchangeably in this disclosure and such use should not limit the scope of the claims appended herewith. In some embodiments, a user of the display can face the portion concavely curving in a horizontal direction (left and right directions of the observer). More specifically, the user faces the display device from the side of the second substrate 120. The first substrate 1 10 and second substrate 120 can also be bent to have respective predetermined radii of curvature sharing a common center point or central axis. In the illustrated, non-limiting embodiment, the center of the curvature radius in the horizontal direction is positioned below the second substrate 120 in FIG. 2, that is, at the side at which the user is positioned to observe the image displayed on the display. An exemplary liquid crystal layer 130 injected between the first substrate 1 10 and the second substrate 120 may include any one of or all types of liquid crystal materials known in the art, such as a TN (twisted nematic) mode, a VA (vertical aligned) mode, an IPS (in plane switching) mode, a BP (blue phase) mode, a FFS (Fringe Field Switching) mode, and an ADS (Advanced Super Dimension Switch) mode, to name a few. Further, although not shown in the figures, an initial liquid crystal (LC) alignment layer may be included in at least one of the first substrate 1 10 and second substrate 120. Further, the alignment layer may be rubbed in a predetermined direction or optically aligned so that the LC molecules possess an initial alignment when an electric field is not present. Alternatively, at least one of the liquid crystal layer 130 and the alignment layer may include a photopolymerization material.

[0031] As noted above, when display devices panels are bent or curved light leakage from a display device may result in a visible artifact to a user. Whether such bending occurs intentionally or unintentionally, the curvature of the glass causes stress retardation in the LCD substrate glasses whose birefringence optically couples with the liquid crystal resulting in light leakage in many embodiments such as the IPS, FFS and ADS modes where the liquid crystal molecular axis is in a plane parallel to the substrate glass. For example, and with reference to FIG. 6, a simplified depiction of a lamination process, one or more polarizers or polarizing films 61, 63 can be laminated onto a glass substrate, sheet or panel 62 using conventional polarizing film laminating machines 64. If, however, the lamination tension differs between the top and the bottom polarizers 61 , 63, the panel 62 may unintentionally curve. It should be noted that the terms panel, sheet, substrate, device and derivations of these terms can be used interchangeably in this disclosure and such use should not limit the scope of the claims appended herewith.

[0032] FIG. 3 is a schematic illustration showing the operation principles of an In-Plane Switching (IPS) mode, and FIG.4 is a photographic illustration of light leakage in an IPS panel under three-point bending. With reference to FIG. 3, front and rear polarizing filters 32, 34 have their axes of transmission in orthogonal directions. To obtain a homogeneously aligned nematic structure of the LC layer 36 between the two glass sheets 35, 37 without an applied electric field (OFF state), the inner surfaces of the glass sheets are treated to align the bordering LC molecules at a parallel direction.

Because they are in the same plane and on a single glass sheet, they generate an electric field parallel to this sheet. The LC molecules have a positive dielectric anisotropy and align themselves with their long axis parallel to an applied electrical field. In the OFF state (shown on the left side of FIG. 3), entering light becomes linearly polarized by the rear polarizer, and the homogeneously aligned LC layer does not change the polarization state of the light, so that ideally no light passes through the front polarizer. In the ON state (shown on the right side of FIG. 3), a sufficient voltage can be applied between electrodes and a corresponding electrical field E generated that realigns the LC molecules 39 as shown. In this case, light can pass through the front polarizer. In practice, other schemes of implementation exist with a different structure of the LC molecules, e.g., with a twist in the OFF state. With reference to FIG. 4, actual light leakage pattern in a bent IPS panel under three point bending can be observed in the circled sections 40a-d of the panel. Such a visible light leakage can interfere with viewing experiences of a user.

[0033] FIG. 7 is a block diagram illustrating an exemplary process according to some embodiments. With reference to FIG. 7, one exemplary process of manufacturing an LCD panel and mitigating light leakage therefrom may include dispensing an identical adhesive at each of the sides of a panel at step 70 and curing the adhesive on the left and right sides of the panel, (e.g., between the thin film transistor and color filter array glass sheets, or the sides parallel to the bending axis of the panel as shown in FIG. 5) at step 72. After the panel is curved in step 74, the adhesive on the top and bottom sides of the panel can be cured in step 76. Through such a selective curing process, registration between the two glass panels can be obtained and light leakage substantially eliminated from an exemplary LCD device.

[0034] FIG. 8 is a block diagram illustrating another process according to some embodiments. With reference to FIG. 8, another exemplary process of manufacturing an LCD panel may include dispensing an identical adhesive at each of the sides of a panel at step 80 and curing the adhesives on the left and right sides of the panel, (e.g., the sides parallel to the bending axis of the panel as shown in FIG. 5) and partially curing the adhesives on the top and bottom sides of the panel at step 82. After the panel is curved in step 84, the curing of the adhesive on the top and bottom sides of the panel can be completed in step 86. Through such a selective curing process, registration between the two glass panels can be obtained and light leakage substantially eliminated from an exemplary LCD device. [0035] FIG. 9 is a block diagram illustrating a process according to further embodiments. With reference to FIG. 9, a further exemplary process of manufacturing an LCD panel may include dispensing an adhesive on the left and right sides of the panel with a high rigidity and dispensing an adhesive on the top and bottom sides of the panel with a lower rigidity at step 90. Each or one of these adhesives can be partially or completely cured before the panel is curved at step 92. After the panel is curved in step 94, the curing of the adhesives (high and/or low rigidity) can be completed if not already conducted during step 92. Through such a selective curing process, registration between the two glass panels can be obtained and light leakage substantially eliminated from an exemplary LCD device.

[0036] FIG. 10 is a block diagram illustrating a process according to additional embodiments. With reference to FIG. 10, another exemplary process of manufacturing an LCD panel may include dispensing an identical adhesive at each of the sides of a panel in step 91 and fully curing the adhesives on the left and right sides of the panel (e.g., the sides parallel to the bending axis of the panel as shown in FIG. 5) in step 93. After curving the panel in step 95, the curing process can then proceed from the least stress impacted portion of the panel (in this non-limiting example, the center of the top and bottom sides of the panel) to the higher stress impacted portions of the panel (e.g., outward from the center portions of the top and bottom sides) in step 97. Through such a selective curing process, registration between the two glass panels can be obtained and light leakage substantially eliminated from an exemplary LCD device.

[0037] FIG. 13 is a light leakage map of an LCD panel under curve. With reference to FIG. 13, a mapping showing light leakage of the LCD panel in IPS mode is provided upon implementation of a uniaxial bend illustrated in FIG. 5. Light leakage can be observed on the four positions close to the display corners 200a-d. After removing the left and right adhesive portions of the panel (see e.g., FIG. 1 1), light leakage persists with a different and more extended area pattern from the display corners 210a-d as illustrated in FIG. 14. It was unexpectedly discovered, however, that a panel having the top and bottom adhesive portions removed (see, e.g., FIG. 12) did not exhibit light leakage upon a uniaxial bend as illustrated in the light leakage map of FIG. 15. Thus, through this experiment and through additional experimentation described above, Applicant demonstrated the control of light leakage in an LCD panel through consideration of the order of the bonding of polarizing films in combination with the curving or bending of the panel. In further embodiments, it was also determined that the adhesives on sides with small or no impact to the light leakage can substantially guarantee TFT CFA glass positional registration.

[0038] While embodiments heretofore have described methods of

manufacturing to mitigate and eliminate light leakage from LCDs, the claims should not be so limited. For example, additional methods may include using one or more sheets or panels of glass in a display unit having differing or low stress optical coefficients alone or in combination with embodiments described herein.

[0039] The glass panels, sheets or substrates described herein may comprise any glass known in the art for use in a backlit display, such as an LCD, including, but not limited to, soda-lime silicate, aluminosilicate, alkali-aluminosilicate, borosilicate, alkali- borosilicate, aluminoborosilicate, alkali-aluminoborosilicate, and other suitable glasses. The glass substrate may, in various embodiments, be chemically strengthened and/or thermally tempered. Non-limiting examples of suitable commercially available substrates include EAGLE XG ^® , Lotus™, Willow ^® , and Gorilla ^® glasses from Corning Incorporated, to name a few. Such chemically strengthened glass, for example, may be provided in accordance with U.S. Patent Nos. 7,666,51 1, 4,483,700, and 5,674,790, which are incorporated herein by reference in their entireties.

[0040] In non-limiting embodiments, the glass sheets, panels or substrates can have a thickness of less than or equal to about 3 mm, for example, ranging from about 0.1 mm to about 2 mm, from about 0.3 mm to about 1.5 mm, from about 0.5 mm to about 1.1 mm, or from about 0.7 mm to about 1 mm, including all ranges and subranges

therebetween. According to various embodiments, the glass substrate can have a thickness of less than or equal to 0.3 mm, such as 0.2 mm, or 0.1 mm, including all ranges and subranges therebetween. In certain non-limiting embodiments, the glass substrate can have a thickness ranging from about 0.3 mm to about 1.5 mm, such as from about 0.5 to about 1 mm, including all ranges and subranges therebetween.

[0041] The glass sheets, panels or substrates can have any shape and/or size suitable for use in an LCD. For example, the glass substrate can be a glass sheet in the shape of a rectangle, square, circle, or any other suitable shape. The glass substrate can, in various embodiments, be transparent or substantially transparent. As used herein, the term "transparent" is intended to denote that the glass substrate, at a thickness of approximately 1mm, has a transmission of greater than about 80% in the visible region of the spectrum (420-700nm). For instance, an exemplary transparent glass substrate may have greater than about 85% transmittance in the visible light range, such as greater than about 90%, or greater than about 95%, including all ranges and subranges therebetween. In certain embodiments, an exemplary glass substrate may have a transmittance of greater than about 50% in the ultraviolet (UV) region (200-4 lOnm), such as greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, greater than about 80%, greater than about 85%, greater than about 90%, greater than about 95%, or greater than about 99% transmittance, including all ranges and subranges therebetween

[0042] It will be appreciated that the various disclosed embodiments may involve particular features, elements or steps that are described in connection with that particular embodiment. It will also be appreciated that a particular feature, element or step, although described in relation to one particular embodiment, may be interchanged or combined with alternate embodiments in various non-illustrated combinations or permutations.

[0043] It is also to be understood that, as used herein the terms "the," "a," or "an," mean "at least one," and should not be limited to "only one" unless explicitly indicated to the contrary. Thus, for example, reference to "a condenser" includes examples having two or more such condensers unless the context clearly indicates otherwise.

[0044] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, examples include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0045] The terms "substantial," "substantially," and variations thereof as used herein are intended to note that a described feature is equal or approximately equal to a value or description. Moreover, "substantially similar" is intended to denote that two values are equal or approximately equal. In some embodiments, "substantially similar" may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0046] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.

[0047] While various features, elements or steps of particular embodiments may be disclosed using the transitional phrase "comprising," it is to be understood that alternative embodiments, including those that may be described using the transitional phrases "consisting" or "consisting essentially of," are implied. Thus, for example, implied alternative embodiments to a system that comprises A+B+C include

embodiments where a system consists of A+B+C and embodiments where a system consists essentially of A+B+C. [0048] It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit and scope of the disclosure. Since modifications combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the disclosure may occur to persons skilled in the art, the disclosure should be construed to include everything within the scope of the appended claims and their equivalents.