Abstract:
A curved display device comprises: a first substrate and a second substrate facing each other and having a curvature; a liquid crystal layer between the first and second substrates; a first polarizing layer between the liquid crystal layer and a first surface of the first substrate that faces the liquid crystal layer, or positioned to face a second surface of the first substrate opposite to the first surface of the first substrate; and a second polarizing layer between the liquid crystal layer and a first surface of the second substrate that faces the liquid crystal layer, or positioned to face a second surface of the second substrate opposite to the first surface of the second substrate; wherein at least one of the first and second polarizing layers is either between the first substrate and the liquid crystal layer or between the second substrate and the liquid crystal layer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on, and claims priority from, Korean Patent Application No. 10-2014-0156212 filed on Nov. 11, 2014 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the present invention relate generally to flat panel displays. More specifically, embodiments of the present invention relate to curved display devices. 
         [0004]    2. Description of the Prior Art 
         [0005]    A liquid crystal display is one example of display devices that have seen wide acceptance. The liquid crystal display functions by controlling the quantity of light that penetrates a liquid crystal layer interposed between electrodes (i.e., a pixel electrode and a common electrode) formed on two substrates that face each other. This is accomplished by controlling orientations of liquid crystal molecules of the liquid crystal layer through applying of voltages to the electrodes. 
         [0006]    In a liquid crystal display, a liquid crystal panel is composed of elements that are not self-luminous, and thus a backlight unit for supplying light to the liquid crystal panel is required. Further, polarizing plates having permeation axes that are orthogonal to each other are attached to outsides of the substrates of the liquid crystal panel. 
       SUMMARY 
       [0007]    It is sometimes desirable to fabricate curved liquid crystal displays. For example, curved displays may provide a panoramic effect for the viewer, heightening the immersive experience. 
         [0008]    As an example, a curved display device may be manufactured through fastening of a flat liquid crystal panel to a backlight unit having a curvature. However, in the process of fastening the liquid crystal panel to the backlight unit, stress may occur in the liquid crystal panel. In particular, stress occurs in portions of substrates of the liquid crystal panel which are bent to conform to the curvature of the backlight unit, resulting in liquid crystal panel substrates that exhibit optical anisotropy. Due to this, unwanted light may permeate a polarizing plate to cause unwanted images to be displayed on the curved display device. In particular, in the case of displaying a black image on the curved display device, a light leakage phenomenon may occur, resulting in detrimental visual effects such as black blurring. 
         [0009]    Accordingly, one subject to be solved by the present invention is to provide a curved display device which can reduce a display of unwanted images resulting from stress induced in the display substrates. 
         [0010]    Additional advantages, subjects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. 
         [0011]    In one aspect of the present invention, there is provided a curved display device comprising: a first substrate and a second substrate facing each other and having a curvature; a liquid crystal layer arranged between the first substrate and the second substrate; a first polarizing layer arranged between the liquid crystal layer and a first surface of the first substrate that faces the liquid crystal layer, or positioned to face a second surface of the first substrate, the second surface of the first substrate being opposite to the first surface of the first substrate; and a second polarizing layer arranged between the liquid crystal layer and a first surface of the second substrate that faces the liquid crystal layer, or positioned to face a second surface of the second substrate, the second surface of the second substrate being opposite to the first surface of the second substrate. At least one of the first polarizing layer and the second polarizing layer is arranged either between the first substrate and the liquid crystal layer or between the second substrate and the liquid crystal layer. 
         [0012]    A thickness of the first substrate may be equal to a thickness of the second substrate. 
         [0013]    The first polarizing layer may be arranged between the first substrate and the liquid crystal layer, and the second polarizing layer may be arranged to face the second surface of the second substrate. 
         [0014]    The first polarizing layer may be positioned to face the second surface of the first substrate, and the second polarizing layer may be arranged between the second substrate and the liquid crystal layer. 
         [0015]    The first polarizing layer may be arranged between the first substrate and the liquid crystal layer, and the second polarizing layer may be arranged between the second substrate and the liquid crystal layer. 
         [0016]    A thickness of the first substrate may be thinner than a thickness of the second substrate. 
         [0017]    The first polarizing layer may be arranged to face the second surface of the first substrate, and the second polarizing layer may be arranged between the second substrate and the liquid crystal layer. 
         [0018]    A thickness of the second substrate may be thinner than a thickness of the first substrate. 
         [0019]    The first polarizing layer may be arranged between the first substrate and the liquid crystal layer, and the second polarizing layer may be arranged to face the second surface of the second substrate. 
         [0020]    The first polarizing layer may be arranged between the first substrate and the liquid crystal layer and may come in direct contact with the first substrate. 
         [0021]    The curved display may further comprise thin film transistors arranged between the first polarizing layer and the liquid crystal layer, wherein the first polarizing layer may be arranged between the first substrate and the thin film transistors. 
         [0022]    The second polarizing layer may be arranged between the second substrate and the liquid crystal layer and may come in direct contact with the second substrate. 
         [0023]    The first polarizing layer may be formed to have a first optical axis, and the second polarizing layer may be formed to have a second optical axis that is substantially perpendicular to the first optical axis. 
         [0024]    The curved display device may further comprise a backlight unit arranged on a lower portion of the first substrate to supply light. 
         [0025]    The first substrate may comprise a display area in which an image is to be displayed and in which a plurality of pixels are defined, as well as a non-display area positioned proximate to least one side of the display area. 
         [0026]    The first polarizing layer may be an absorption type polarizing layer, and the second polarizing layer may be an absorption type polarizing layer, and the first polarizing layer and the second polarizing layer may be arranged over substantially an entire surface of the first substrate or may be arranged to overlap at least the display area of the first substrate. 
         [0027]    The curved display device may further comprise a first electrode arranged in a pixel of the first substrate and arranged between the first polarizing layer and the liquid crystal layer, wherein the first polarizing layer is a reflection type polarizing layer, and the second polarizing layer is an absorption type polarizing layer, and the first polarizing layer may include a plurality of metal lines which are arranged over substantially the entire first substrate, arranged to overlap the display area of the first substrate, or arranged to overlap the first electrode of the first substrate. 
         [0028]    The curved display device may further comprise a first electrode arranged in a pixel of the first substrate and arranged between the first polarizing layer and the liquid crystal layer, wherein the first polarizing layer may be an absorption type polarizing layer, and the second polarizing layer may be a reflection type polarizing layer, and the second polarizing layer may include a plurality of metal lines which are arranged on the second substrate to overlap the first electrode. 
         [0029]    The curved display device may further comprise: thin film transistors arranged between the first polarizing layer and the first electrode; and a black matrix arranged on the second substrate so as to overlap the thin film transistors, wherein the first electrode may include a first sub-electrode and a second sub-electrode arranged so that the thin film transistors are interposed between the first sub-electrode and the second sub-electrode, and the second polarizing layer may be positioned at a same level as the level of the black matrix. 
         [0030]    The curved display device may further comprise a first electrode arranged in a pixel of the first substrate and arranged between the first polarizing layer and the liquid crystal layer, wherein the first polarizing layer may be a reflection type polarizing layer, and the second polarizing layer may be a reflection type polarizing layer, the first polarizing layer may include a plurality of metal lines which are arranged over substantially the entire first substrate, arranged to overlap the display area on the first substrate, or arranged to overlap the first electrode on the first substrate, and the second polarizing layer may include a plurality of metal lines arranged to overlap the first electrode. 
         [0031]    According to embodiments of the present invention, at least the following effects can be achieved. 
         [0032]    According to the curved display device according to an embodiment of the present invention, at least one of the first polarizing layer and the second polarizing layer is arranged inside the display panel, preventing undesired visual effects caused by optical anisotropy in the display substrates due to stress caused by their attachment to a curved display device. 
         [0033]    The effects according to the present invention are not limited to the contents as exemplified above, but further various effects are included in the description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0035]      FIG. 1  is a perspective view of a curved display device in an assembled state according to an embodiment of the present invention; 
           [0036]      FIG. 2  is a perspective view of the curve display device of  FIG. 1  in a separated state; 
           [0037]      FIG. 3  is a schematic layout diagram of a display panel of  FIG. 2 ; 
           [0038]      FIG. 4  is a plan view of three pixels explaining a display panel of  FIG. 2 ; 
           [0039]      FIG. 5  is a cross-sectional view of the display panel of  FIG. 4 , the cross-section taken along line I-I′ of  FIG. 4 ; 
           [0040]      FIG. 6  is a layout diagram illustrating an arrangement of a first polarizing layer on a first substrate of a display panel of  FIG. 2 ; 
           [0041]      FIG. 7  is a layout diagram illustrating an arrangement of a second polarizing layer on a second substrate of a display panel of  FIG. 2 ; 
           [0042]      FIG. 8  is a cross-sectional view of another embodiment of a display panel that corresponds to the display panel of  FIG. 5 ; 
           [0043]      FIG. 9  is a plan view of one pixel explaining the display panel of  FIG. 8 ; 
           [0044]      FIG. 10  is a layout diagram illustrating an arrangement of a first polarizing layer on a first substrate of the display panel of  FIG. 8 ; 
           [0045]      FIGS. 11 and 12  are layout diagrams illustrating various embodiments of the first polarizing layer of  FIG. 10 ; 
           [0046]      FIG. 13  is a cross-sectional view of still another embodiment of a display panel that corresponds to the display panel of  FIG. 5 ; 
           [0047]      FIG. 14  is a cross-sectional view of a still further embodiment of a display panel that corresponds to the display panel of  FIG. 5 ; 
           [0048]      FIG. 15  is a plan view of one pixel explaining the display panel of  FIG. 14 ; 
           [0049]      FIG. 16  is a cross-sectional view of still another embodiment of a display panel that corresponds to the display panel of  FIG. 5 ; 
           [0050]      FIG. 17  is a cross-sectional view of yet another embodiment of a display panel that corresponds to the display panel of  FIG. 5 ; and 
           [0051]      FIG. 18  is a cross-sectional view of a still further embodiment of a display panel that corresponds to the display panel of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0052]    Advantages and features of the present invention and methods of accomplishing the same may be understood more readily by reference to the following detailed description of preferred embodiments and the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art, and the present invention will only be defined by the appended claims. 
         [0053]    It will also be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. The same reference numbers indicate the same components throughout the specification. The various Figures are not to scale. 
         [0054]    It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. 
         [0055]    Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 
         [0056]      FIG. 1  is a perspective view of a curved display device in an assembled state according to an embodiment of the present invention.  FIG. 2  is a perspective view of the curve display device of  FIG. 1  in a separated state, and  FIG. 3  is a schematic layout diagram of a display panel of  FIG. 2 . 
         [0057]    Referring to  FIGS. 1 to 3 , at least part of a curved display device  50  may have a curvature. The device  50  may include a display panel  10 , a backlight unit  20 , a middle receptacle  30 , and an upper receptacle  40  which have a shape that corresponds to the curvature. 
         [0058]    The display panel  10  is to display an image, and may include a first display plate  100  and a second display plate  200  that face each other. The first display plate  100  and the second display plate  200  may be bonded together by a sealant (not illustrated) in known manner. A liquid crystal layer LC (in  FIG. 5 ) may be interposed between the first display plate  100  and the second display plate  200 . 
         [0059]    Each of the first display plate  100  and the second display plate  200  of the display panel  10  includes a display area DA in which an image is displayed, and a non-display area NDA that is positioned on at least one side of the display area DA. A plurality of pixels PX that are arranged in a matrix form may be defined in the display area DA. Each pixel PX may include a pixel area PA (in  FIG. 6 ) in which a first electrode PE (in  FIG. 6 ) is formed, and a non-pixel area NPA (in  FIG. 6 ) that is the area of pixel PX outside the pixel area PA (in  FIG. 6 ). A gate pad GP (in  FIG. 4 ) and a data pad DP (in  FIG. 4 ) may be formed in the non-display area NDA. Although  FIG. 3  illustrates that the non-display area NDA is formed to correspond to four sides of the display panel  10  in the form of the area surrounding the display area DA, the non-display area NDA may be formed to correspond to less than four sides. 
         [0060]    The backlight unit  20  provides light to the display panel  10 , and may include a lower receptacle  21 , one or more light source modules  22 , a reflective sheet  26 , an optical plate  27 , and an optical sheet  28 . 
         [0061]    The lower receptacle  21  accommodates the light source modules  22 , the reflective sheet  26 , the optical plate  27 , and the optical sheet  28 . The lower receptacle  21  may be a bottom chassis. The lower receptacle  21  may include a recessed portion (not illustrated) in which the light source modules  22  are arranged. 
         [0062]    Each light source module  22  may include a plurality of light sources  23 , for example LED (Light Emitting Diode) light sources, that generate light to be provided to the display panel  10 , a printed circuit board  24  that provides power for driving the plurality of light sources  23 , and optical lenses  25  that diffuse the light emitted from the plurality of light sources  23 . 
         [0063]    The reflective sheet  26  serves to reflect light that is directed downward, back upward toward the display panel  10 . The reflective sheet  26  may be a single unitary and continuous sheet, or may have holes or cutouts for each light source  23 . In particular, the reflective sheet  26  may include openings  26   a  corresponding in number to the number of light sources  23 . 
         [0064]    The optical plate  27  and the optical sheet  28  are optical modulation structures arranged on an upper portion of the light source module  22  to modulate the light from light sources  23 . In an exemplary embodiment, the optical plate  27  may be a diffusion plate. The optical sheet  28  may be, for example, a prism sheet, a diffusion sheet, a micro lens sheet, a lenticular sheet, a phase difference compensation sheet, a reflective polarizing sheet, or the like. Any number and combination of such sheets is contemplated. 
         [0065]    The middle receptacle  30  is arranged on an upper portion of the optical sheet  28 , and may be, for example, a mold frame or a middle mold. The middle receptacle  30  may be fixed to or fastened to the lower receptacle  21 . The middle receptacle  30  may accommodate the display panel  10 , the optical plate  27 , and the optical sheet  28 . 
         [0066]    The upper receptacle  40  is arranged on an upper portion of the display panel  10 , and may be a top chassis or a bezel. The upper receptacle includes an open or transparent window, and covers an edge of the display panel  10 . The upper receptacle  40  may be bonded to the lower receptacle  21 . 
         [0067]    Hereinafter, the display panel  10  will be described in more detail. The configuration of the display panel  10  will be described with reference to one pixel PX. 
         [0068]      FIG. 4  is a plan view of three pixels of a display panel of  FIG. 2 , and  FIG. 5  is a cross-sectional view of the display panel of  FIG. 4  taken along line I-I′ of  FIG. 4 .  FIG. 6  is a layout diagram illustrating an arrangement of a first polarizing layer on a first substrate of a display panel of  FIG. 2 , and  FIG. 7  is a layout diagram illustrating an arrangement of a second polarizing layer on a second substrate of a display panel of  FIG. 2 . 
         [0069]    Referring to  FIGS. 4 and 5 , the first display plate  100  of the display panel  10  includes a first substrate  110 , a first polarizing layer  120 , a first insulating layer  130 , a gate line GL, a data line DL, a storage line SL, a reference line RL, a gate insulating layer  140 , a first thin film transistor TFT 1 , a second thin film transistor TFT 2 , a third thin film transistor TFT 3 , a protection layer  150 , and a first electrode (which may in some embodiments be referred to as a pixel electrode) PE (the combination of PE 1  and PE 2 ). 
         [0070]    The first substrate  110  has a curvature at least partly conforming to the shape of the curved display device  50 , and may include a display area DA and a non-display area NDA. The first substrate  110  may include a material having superior permeability to light, heat resistance, and chemical resistance. For example, the first substrate  110  may include any one of glass, polyethylenenaphthalate, polyethyleneterephthalate, and polyacryl, which have superior light permeability. The first substrate  110  may have a first thickness t 1 . Since the flat display panel  10  is fastened to a backlight unit  20  that has a curvature, the first substrate  110  may be subjected to a first stress during the process of manufacturing the curved display device  50 . 
         [0071]    The first polarizing layer  120  is formed between the first substrate  110  and the liquid crystal layer LC. For example, the first polarizing layer  120  may be formed between the first substrate  110  and the thin film transistors TFT 1 , TFT 2 , and TFT 3 . That is, the first polarizing layer  120  is formed on the first substrate  110  prior to other structures including the thin film transistors TFT 1 , TFT 2 , and TFT 3 , and thus may not be affected by high temperature that is applied to form these other structures. Further, the first polarizing layer  120  may be arranged directly on the first substrate  110 , and may be easily deposited on and attached to the flat upper surface of the first substrate  110 .  FIG. 6  illustrates that the first polarizing layer  120  is arranged on, and covers, substantially the entire first substrate  110 , but the embodiments are not limited thereto. In some embodiments, the first polarizing layer  120  may be arranged to correspond only to the display area DA. 
         [0072]    The first polarizing layer  120  polarizes interior light, provided from the backlight unit  20 , in a specific direction. For example, the first polarizing layer  120  is formed to have an optical axis OA 1  (in  FIG. 6 ) of 0°, and thus polarizes the internal light along an axis oriented at 0°. The first polarizing layer  120  polarizes the internal light that has already passed through the first substrate  110 . Accordingly, even if phase retardation of the internal light occurs due to an optical anisotropy phenomenon that occurs on the first substrate  110 , the first polarizing layer  120  polarizes the internal light after any such phase retardation has already occurred, so that the light provided to the liquid crystal layer LC is polarized even if it is phase-retarded. Optical anisotropy may be generated by the stress induced in the first substrate  110  by the process of manufacturing a curved display device  50 , typically through fastening of the flat display panel  10  to the curved backlight unit  20 . That is, when the flat display panel  10  is fastened to a backlight unit  20  having curvature, the first stress occurs in portions of the first substrate  110  which are bent to conform to the curvature of the backlight unit  20  and portions of the first substrate  110  corresponding to the fastening points of the display panel  10  and the backlight unit  20 , resulting in the first substrate  110  that exhibits optical anisotropy. 
         [0073]    On the other hand, if the first polarizing layer  120  is arranged outside the first substrate  110 , the polarization characteristic of the light that is provided to the liquid crystal layer LC may differ from the polarization characteristic of the internal light that is polarized by the first polarizing layer  120 . This is because phase retardation may occur in internal light that is first polarized by the first polarizing layer  120  and then passes through an optically anisotropic first substrate  110 . 
         [0074]    The first polarizing layer  120  may be an absorption type polarizing layer that absorbs light that is not oriented in the specific direction, or a reflection type polarizing layer that reflects light that is nor oriented in the specific direction. The absorption type polarizing layer may be formed by, for example, dyeing iodine or dichroic dyes to a stretched polyvinyl alcohol film. The reflection type polarizing layer may be formed by, for example, patterning a conductive material, and may be formed as a wire grid polarization pattern.  FIGS. 5 and 6  illustrate a case where the first polarizing layer  120  is implemented as an absorption type polarizing layer. 
         [0075]    The first insulating layer  130  is arranged on the first polarizing layer  120 . The first insulating layer  130  may serve to planarize and protect the first polarizing layer  120 . The first insulating layer  130  may include, as an example, silicon oxide (SiOx). The first insulating layer  130  may be omitted. 
         [0076]    The gate line GL is formed on the first substrate  110 , and specifically is formed to extend generally in the first direction on the first insulating layer  130 , and acts to transfer a gate signal. A gate pad GP is connected to one end of the gate line GL, and a gate pad electrode GPE may be formed on the gate pad GP. The gate pad electrode GPE is a contact electrode for connecting an external wire for applying a signal to the first electrode PE. 
         [0077]    The data line DL is formed on the first substrate  110 , and specifically is formed to extend generally in a second direction that crosses the first direction on the gate insulating layer  140 . The data line DL is insulated from the gate line GL, and acts to transfer a data signal. A data pad DP is connected to one end of the data line DL. A data pad electrode DPE may be formed on the data pad DP. The data pad electrode DPE is another contact electrode for connecting an external wire for applying a signal to the first electrode PE. 
         [0078]    The storage line SL is formed on the first substrate  110 , and specifically is formed to extend generally in the first direction on the first insulating layer  130 . It further includes branch electrodes that branch out in the second direction to surround the first electrode PE (PE 1  and PE 2 ). The storage line SL may form a hold capacitor along with the first electrode PE, to strengthen the voltage hold capability of a liquid crystal capacitor that is formed between the first electrode PE and a second electrode CE. 
         [0079]    The gate insulating layer  140  covers the gate line GL, the storage line SL, and the gate pad GP that are formed on the first insulating layer  130 , and is formed of an insulating material. For example, the gate insulating layer  140  may include an inorganic material, such as silicon nitride (SiNx) or silicon oxide (SiOx). 
         [0080]    The first thin film transistor TFT 1  is arranged between the first polarizing layer  120  and the liquid crystal layer LC, is connected between the gate line GL and the data line DL, and includes a first gate electrode GE 1 , a first semiconductor layer SM 1 , a first source electrode SE 1 , and a first drain electrode DE 1 . 
         [0081]    The first gate electrode GE 1  may be formed to project from the gate line GL to underlie the first semiconductor layer SM 1 . The first gate electrode GE 1  may include, for example, any one of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO). Further, the first gate electrode GE 1  may have a two-layer structure that includes a first electrode layer that is composed of the above-described material, and a second electrode layer that may be made of a metal, such as copper (Cu), molybdenum (Mo), aluminum (Al), tungsten (W), chrome (Cr), or titanium (Ti), or an alloy including at least one of the above-described metals. 
         [0082]    The first semiconductor layer SM 1  is formed on the first gate electrode GE 1  so that the gate insulating layer  140  is interposed between the first semiconductor layer SM 1  and the first gate electrode GE 1 . The first semiconductor layer SM 1  may include an active layer provided on the gate insulating layer  140  and an ohmic contact layer provided on the active layer. Additionally, the first semiconductor layer SM 1  may be formed between the data line DL and the gate insulating layer  140 . Further, the first semiconductor layer SM 1  may be formed between the data pad DP and the gate insulating layer  140 . 
         [0083]    The first source electrode SE 1  is formed to project from the data line DL, and overlaps at least a part of the first gate electrode GE 1  in plan view (i.e. the view of  FIG. 4 ). The first drain electrode DE 1  is formed to be spaced apart from the first source electrode SE 1 , and overlaps at least a part of the first gate electrode GE 1  in plan view. The first drain electrode DE 1  is connected to a first sub-electrode PE 1  of the first electrode PE through a first contact hole CH 1  that is formed in the protection layer  150 . The first source electrode SE 1  and the first drain electrode DE 1  may be formed of, for example, a metal, such as copper, molybdenum, aluminum, tungsten, chrome, or titanium, or an alloy that includes at least one of the above-described metals. Here, the first source electrode SE 1  and the first drain electrode DE 1  both overlap parts of the first semiconductor layer SM 1  and are separated thereon by a gap distance. 
         [0084]    The second thin film transistor TFT 2  is arranged between the first polarizing layer  120  and the liquid crystal layer LC, is connected between the gate line GL and the data line DL, and includes a second gate electrode GE 2 , a second semiconductor layer SM 2 , a second source electrode SE 2 , and a second drain electrode DE 2 . 
         [0085]    The second gate electrode GE 2  is formed to project from the gate line GL to underlie the second semiconductor layer SM 2  in plan view, and is connected to the first gate electrode GE 1 . The second gate electrode GE 2  may be formed of the same material as the material of the first gate electrode GE 1 . As can be seen, gate electrodes GE 1  and GE 2  may be parts of a single continuous protrusion from gate line GL. 
         [0086]    The second semiconductor layer SM 2  is formed on the second gate electrode GE 2  so that the gate insulating layer  140  is interposed between the second semiconductor layer SM 2  and the second gate electrode GE 2 . The second semiconductor layer SM 2  may include an active layer provided on the gate insulating layer  140  and an ohmic contact layer provided on the active layer. Additionally, the second semiconductor layer SM 2  may be formed between the data line DL and the gate insulating layer  140 . Further, the second semiconductor layer SM 2  may also be formed between the data pad DP and the gate insulating layer  140 . 
         [0087]    The second source electrode SE 2  is connected to the first source electrode SE 1 , and overlaps at least a part of the second gate electrode GE 2  in plan view. The second drain electrode DE 2  is formed to be spaced apart from the second source electrode SE 2 , and overlaps at least a part of the second gate electrode GE 2  in plan view. The second drain electrode DE 2  is connected to a second sub-electrode PE 2  of the first electrode PE through a second contact hole CH 2  that is formed in the protection layer  150 . Here, the second source electrode SE 2  and the second drain electrode DE 2  overlap the second semiconductor layer SM 2  and are spaced apart from each other thereon by a gap. The second source electrode SE 2  and the second drain electrode DE 2  may be formed of the same material as the material of the first source electrode SE 1  and the first drain electrode DE 1 . 
         [0088]    The third thin film transistor TFT 3  is arranged between the first polarizing layer  120  and the liquid crystal layer LC, is connected between the gate line GL and the data line DL, and includes a third gate electrode GE 3 , a third semiconductor layer SM 3 , a third source electrode SE 3 , and a third drain electrode DE 3 . 
         [0089]    The third gate electrode GE 3  is formed to project from the gate line GL to underlie the third semiconductor layer SM 3  in plan view, and is spaced apart from the second gate electrode GE 2 . The third gate electrode GE 3  may be formed of the same material as the material of the first gate electrode GE 1 . 
         [0090]    The third semiconductor layer SM 3  is formed on the third gate electrode GE 3  so that the gate insulating layer  140  is interposed between the third semiconductor layer SM 3  and the third gate electrode GE 3 . The third semiconductor layer SM 3  may include an active layer provided on the gate insulating layer  140  and an ohmic contact layer provided on the active layer. Also, the third semiconductor layer SM 3  may be formed between the data line DL and the gate insulating layer  140 . Further, the third semiconductor layer SM 3  may be formed between the data pad DP and the gate insulating layer  140 . 
         [0091]    The third source electrode SE 3  is connected to the second drain electrode DE 2 , and overlaps at least a part of the third gate electrode GE 3  in plan view. The third drain electrode DE 3  is formed to be spaced apart from the third source electrode SE 3 , and overlaps at least a part of the third gate electrode GE 3  in plan view. The third drain electrode DE 2  is connected to the reference line RL (to be described later) through a third contact hole CH 3  that is formed in the protection layer  150 . Here, the third source electrode SE 3  and the third drain electrode DE 3  overlap a part of the third semiconductor layer SM 3  and are spaced apart from each other thereon by a gap. The third source electrode SE 3  and the third drain electrode DE 3  may be formed of the same material as the material of the first source electrode SE 1  and the first drain electrode DE 1 . 
         [0092]    The protection layer  150  is arranged on the first thin film transistor TFT 1 , the second thin film transistor TFT 2 , and the third thin film transistor TFT 3 . The protection layer  150  may be formed of an inorganic material, such as silicon nitride (SiNx) or silicon oxide (SiOx), or may be formed of a low-k organic insulating layer. Further, the protection layer  150  may have a dual-layer structure including an inorganic insulating layer and an organic insulating layer. The protection layer  150  has the first contact hole CH 1  for exposing a part of the first drain electrode DE 1 , the second contact hole CH 2  for exposing a part of the second drain electrode DE 2 , and the third contact hole CH 3  for exposing a part of the third drain electrode DE 3 . 
         [0093]    The first electrode PE is arranged between the first polarizing layer  120  and the liquid crystal layer LC, and specifically is arranged within pixel PX (in  FIG. 3 ) on the protection layer  150 , and may include first sub-electrode PE 1  and second sub-electrode PE 2  arranged so that the thin film transistors TFT 1 , TFT 2 , and TFT 3  are interposed between the first sub-electrode PE 1  and the second sub-electrode PE 2  in plan view. 
         [0094]    The first sub-electrode PE 1  contacts the first drain electrode DE 1  through the first contact hole CH 1 . The first sub-electrode PE 1  may include a slit pattern having a plurality of openings. For example, the first sub-electrode PE 1  may include a trunk portion PE 1   a , a plurality of branch portions PE 1   b  extending to project from the trunk portion PE 1   a , and a connection electrode PE 1   c  connecting the trunk portion PE 1   a  and the first drain electrode DE 1  to each other. The trunk portion PE 1   a  may be formed to include one horizontal line and three vertical lines. One vertical line may cross the one horizontal line, and the other two vertical lines may be connected to both sides of the one horizontal line. The branch portions PE 1   b  may be formed to extend toward the storage line SL at acute angles with respect to the trunk portion PE 1   a . The trunk portion PE 1   a  and the plurality of branch portions PE 1   b  are not limited to the arrangement as illustrated in  FIG. 4 , but may have various arrangements and shapes. The first sub-electrode PE 1  may include a transparent conductive material. For example, the first sub-electrode PE 1  may include indium tin oxide (ITO) or indium zinc oxide (IZO). The first sub-electrode PE 1  may partially overlap the storage line SL to form a storage capacitor. 
         [0095]    The second sub-electrode PE 2  comes in contact with the second drain electrode DE 2  through the second contact hole CH 2 . Similar to the first sub-electrode PE 1 , the second sub-electrode PE 2  may include a slit pattern having a plurality of openings. For example, the second sub-electrode PE 2  may include a trunk portion PE 2   a , a plurality of branch portions PE 2   b  extending to project from the trunk portion PE 2   a , and a connection electrode PE 2   c  connecting the trunk portion PE 2   a  and the second drain electrode DE 2  to each other. The trunk portion PE 2   a  may be formed to include one horizontal line and three vertical lines. The branch portions PE 2   b  may be formed to extend toward the storage line SL at acute angles with respect to the trunk portion PE 2   a . The trunk portion PE 2   a  and the plurality of branch portions PE 2   b  are not limited to the arrangement as illustrated in  FIG. 4 , but may have various arrangements and shapes. The second sub-electrode PE 2  may be formed of the same material as the material of the first sub-electrode PE 1 . The second sub-electrode PE 2  may partially overlap the storage line SL to form a storage capacitor. Also, the size of the first sub-pixel in which the first sub-electrode PE 1  is arranged may be different from the size of the second sub-pixel in which the second sub-electrode PE 2  is arranged. For example, the size of the second sub-pixel may be larger than the size of the first sub-pixel. 
         [0096]    The reference line RL is arranged on the protection layer  150 . The reference line RL is formed to include a projection portion which extends in the second direction, overlaps a part of the data line DL in plan view, and extends so as to overlap a part of the third thin film transistor TFT 3 . In particular, a projection portion, or extension, of the reference line RL comes in contact with the third drain electrode DE 3  of the third thin film transistor TFT 3 . Further, the reference line RL may be formed to extend into a gap area between the first sub-pixel PE 1  and the second sub-pixel PE 2 . The reference line RL may be formed of the same material as the material of the first sub-electrode PE 1  and the second sub-electrode PE 2 , and may be formed on the same layer as the layer of the first sub-electrode PE 1  and the second sub-electrode PE 2 . 
         [0097]    A reference voltage having the same level as the level of the voltage applied to storage line SL may be applied to the reference line RL. The reference line RL may make the voltage between the second sub-electrode PE 2  and the second electrode CE lower than the voltage between the first sub-electrode PE 1  and the second electrode CE, by lowering of the voltage that is applied to the second sub-electrode PE 2  through the third thin film transistor TFT 3 . Through this, liquid crystal molecules positioned in an area that corresponds to the first sub-pixel and first sub-electrode PE 1 , and liquid crystal molecules positioned in an area that corresponds to the second sub-pixel and second sub-electrode PE 2 , receive different electric field strengths and are thus inclined at different angles. Accordingly, the liquid crystal molecules positioned in the area that corresponds to the first sub-pixel and the liquid crystal molecules positioned in the area that corresponds to the second sub-pixel have different inclination angles, to make the luminance of the first sub-pixel differ from the luminance of the second sub-pixel. Accordingly, side visibility can be improved. Additionally, the reference line RL may act as a shielding electrode that prevents electromagnetic interference between the data line DL and the first electrode PE, and between the data line DL and the second electrode CE. 
         [0098]    The second display plate  200  includes a second substrate  210 , a black matrix BM, a color filter CF, an overcoat layer  220 , second electrode CE, and a second polarizing layer  230 . 
         [0099]    The second substrate  210  has a curvature at least partly corresponding to the shape of the curved display device  50 , and faces the first substrate  110 . The second substrate  210  may include a material having superior visible light permeability, heat resistance, and chemical resistance. For example, the second substrate  210  may include any one of glass, polyethylenenaphthalate, polyethyleneterephthalate, and polyacryl, which have superior light permeability. The second substrate  210  may have a second thickness t 2  that is equal to the first thickness t 1  of the first substrate  110 . In the process of manufacturing the curved display device  50  through fastening of the flat display panel  10  to curved backlight unit  20 , the second substrate  210  may receive a second stress that is approximately equal to the first stress of the first substrate  110 . 
         [0100]    The black matrix BM is arranged on a lower portion of the second substrate  210 . Specifically, the black matrix BM is arranged to correspond to at least part of the non-pixel area NPA. For example, the black matrix BM may overlap the gate line GL and the thin film transistors TFT 1 , TFT 2 , and TFT 3 . That is, in the case where the display panel is curved around an axis corresponding to a direction that is in parallel to the data line to implement the curved display device, an area in which an image is actually displayed (i.e., a portion where the first electrode is formed) can be prevented from being decreased in size due to an invasion of the black matrix that overlaps the data line into the first electrode portion as the first display plate and the second display plate are misaligned. Further, the black matrix BM is arranged to correspond to the non-display area NDA. The black matrix BM as described above intercepts unnecessary light. In some embodiments, the black matrix BM may be formed on the first substrate  110 . In this case, the black matrix BM may overlap the gate line GL, the data line DL, and the thin film transistors TFT 1 , TFT 2 , and TFT 3 . In this case, even if the first display plate and the second display plate are misaligned in the case where the display panel is curved, both the black matrix and the first electrode are positioned on the first substrate, and thus the black matrix that overlaps the data line does not invade the portion where the first electrode is formed. Accordingly, the area in which the image is actually displayed can be prevented from being decreased in size. 
         [0101]    The color filter CF is arranged on a lower portion of the second substrate  210 . The color filter CF is to provide a color to the light that permeates the liquid crystal layer LC. The color filter CF may include a red color filter, a green color filter, a blue color filter, and/or any other desired color. The color filter CF may be provided to correspond to each pixel area PA, and may be arranged to have different colors between adjacent pixels PX. That is, different pixel areas PA may have differently-colored color filters CF. The color filters CF may partially overlap each other or may be spaced apart from each other at boundaries between adjacent pixels PX. In some embodiments, the color filter CF may be formed on the first substrate  110 . 
         [0102]    The overcoat layer  220  is formed on lower portions of the color filter CF and the black matrix BM. The overcoat layer  220  serves to perform planarization, protection, and insulation of the color filter CF, and may be formed, for example, using acrylic epoxy material. 
         [0103]    The second electrode CE may be arranged between the overcoat layer  220  and the liquid crystal layer LC, and may be formed over substantially the entire overcoat layer  220 , although this need not necessarily be the case. The second electrode CE is electrically connected to a common electrode (not illustrated). The second electrode CE may include a transparent conductive material. For example, the second electrode CE may include indium tin oxide (ITO) or indium zinc oxide (IZO). 
         [0104]    The second polarizing layer  230  is arranged outside the second substrate  210 , and may be formed over substantially the entire second substrate  210 . The second polarizing layer  230  polarizes the light that has passed through the liquid crystal layer LC in a direction that is perpendicular to the specific direction as described above. For example, as illustrated in  FIG. 7 , the second polarizing layer  230  is formed to have an optical axis OA 2  of 90°, which is orthogonal to the optical axis OA 1  (in  FIG. 6 ) of 0°, and thus polarizes the light that has passed through the liquid crystal layer LC by 90°. On the other hand, in the case where the alignment of liquid crystal molecules of the liquid crystal layer LC is controlled to display a black image, the light that has passed through the liquid crystal layer LC should not pass through the second polarizing layer  230 . However, if the light that has passed through the liquid crystal layer LC passes through a second substrate  210  having an optical anisotropy phenomenon, phase retardation may occur in the light that has passed through the liquid crystal layer LC. If phase-retarded light is provided to the second polarizing layer  230 , a part of the phase-retarded light may pass through the second polarizing layer  230  to cause a slight light leakage phenomenon to occur during black images. The slight light leakage phenomenon is not greatly recognized, i.e. is not prominently visible, typically. The optical anisotropy phenomenon of the second substrate  230  may occur due to second stress that is generated on the second substrate  230  in the process of manufacturing the curved display device  50  through fastening of the flat display panel  10  to the backlight unit  20  having a curvature. That is, when the flat display panel  10  is fastened to a curved backlight unit  20 , the second stress occurs in portions of the second substrate  230  which are bent to conform to the curvature of the backlight unit  20  and portions of the second substrate  230  corresponding to the fastening points of the display panel  10  and the backlight unit  20 , resulting in the second substrate  230  that exhibits optical anisotropy. 
         [0105]    The second polarizing layer  230  may be an absorption type polarizing layer that absorbs light that is not polarized in the direction that is perpendicular to the specific direction, or a reflection type polarizing layer that reflects light that is not polarized in the direction that is perpendicular to the specific direction. In  FIGS. 5 and 7 , it is illustrated that the second polarizing layer  230  is formed as an absorption type polarizing layer. In the case where the second polarizing layer  230  is formed as a reflection type polarizing layer, the second polarizing layer  230  may absorb an external light that is incident to the second polarizing layer  230 . Thus, a glare phenomenon occurring due to external light that is incident to the second polarizing layer  230  and then is reflected from the second polarizing layer  230  can be decreased.  FIG. 7  illustrates that the second polarizing layer  230  is arranged over substantially the entire second substrate  210 , but embodiments of the invention are not limited thereto. In some embodiments, the second polarizing layer  230  may be arranged to correspond only to the display area DA, for example. 
         [0106]    The liquid crystal layer LC of the display panel  10  includes liquid crystal molecules having a dielectric anisotropy. The long axes of the liquid crystal molecules may be arranged vertically or horizontally with respect to the surfaces of the two display plates  100  and  200 . 
         [0107]    In the curved display device  50  having the above-described structure, the first thin film transistor TFT 1  and the second thin film transistor TFT 2  receive a gate signal that is provided through the gate line GL and a data signal that is provided through the data line DL. Accordingly, the first thin film transistor TFT 1  and the second thin film transistor TFT 2  are turned on, and voltages that correspond to the data signal are provided to the first sub-electrode PE 1  and the second sub-electrode PE 2 , respectively. In this case, the voltage that is applied to the second sub-electrode PE 2  may be divided by turning on the third thin film transistor TFT 3  that is connected to the reference line RL to which the reference voltage is applied, and thus may be lower than the voltage that is applied to the first sub-electrode PE 1 . Electric fields having different levels are thereby formed between the first and second sub-electrodes PE 1  and PE 2 , to which different voltages are supplied, and the second electrode CE, to which the common voltage is applied. In accordance with the different electric fields, the liquid crystal molecules positioned between the first sub-electrode PE 1  and the second electrode CE, and the liquid crystal molecules positioned between the second sub-electrode PE 2  and the second electrode CE, are driven by differing voltages, and as a result, an image is displayed in accordance with the quantity of light that penetrates the liquid crystal layer LC. 
         [0108]    As described above, according to the curved display device  50  according to an embodiment of the present invention, the first polarizing layer  120  is formed between the first substrate  110  and the liquid crystal layer LC, and thus the light provided to the liquid crystal layer LC is polarized even when the first substrate  110  exhibits optical anisotropy. 
         [0109]    Accordingly, in the curved display device  50  according to an embodiment of the present invention, in the case where the first polarizing layer is arranged outside the first substrate, the display of an unwanted image, for example the occurrence of a light leakage phenomenon in a black image, can be prevented. In particular, detrimental effects caused by light having polarization characteristics different from the polarization characteristic of the first polarizing layer can be reduced. 
         [0110]    Next, a curved display device according to another embodiment of the present invention will be described. 
         [0111]      FIG. 8  is a cross-sectional view of a different embodiment of a display panel constructed according to  FIG. 5 .  FIG. 9  is a plan view of one pixel further explaining the display panel of  FIG. 8 , and  FIG. 10  is a layout diagram illustrating an arrangement of a first polarizing layer on a first substrate of the display panel of  FIG. 8 .  FIGS. 11 and 12  are layout diagrams illustrating various embodiments of the first polarizing layer of  FIG. 10 .  FIG. 9  illustrates that the first sub-electrode PE 1  and the second sub-electrode PE 2  are formed in a rectangular area indicated as a dotted line, but the detailed shapes of the first sub-electrode PE 1  and the second sub-electrode PE 2  are omitted. 
         [0112]    Referring to  FIG. 8 , a curved display device according to another embodiment of the present invention has largely the same configuration as the configuration of the curved display device  50  of  FIG. 2 , but display panel  11  is different from the display panel  10  of the curved display device  50 . Accordingly, explanation of the curved display device of the present embodiment will focus on the display panel  11 . 
         [0113]    The display panel  11  may include a first display plate  100   a  and a second display plate  200  that face each other. The first display plate  100   a  and the second display plate  200  may be bonded together by a sealant (not illustrated), as is known. A liquid crystal layer LC may be interposed between the first display plate  100   a  and the second display plate  200 . 
         [0114]    The first display plate  100   a  of the display panel  11  is similar to the first display plate  100  of  FIG. 5 , and includes a first substrate  110 , a first polarizing layer  120   a , a first insulating layer  130   a , a gate line GL, a data line DL, a storage line SL, a reference line RL, a gate insulating layer  140 , a first thin film transistor TFT 1 , a second thin film transistor TFT 2 , a third thin film transistor TFT 3 , a protection layer  150 , and a first electrode PE. 
         [0115]    In this embodiment, the first polarizing layer  120   a  is formed as a reflection type polarizing layer. In this case, the first polarizing layer  120   a  is not a continuous layer, but is instead composed of a plurality of metal lines. The plurality of metal lines  121  are formed to extend in one direction on the first substrate  110  through a patterning method and to be spaced apart from each other at a predetermined interval in a direction that is perpendicular to the one direction. The predetermined interval may be in the range of several tens or several hundreds of nanometers (nm). The one direction may be a direction in which the first polarizing layer  120   a  is to have an optical axis OA 1  of 0°. The first polarizing layer  120   a  may include a conductive material, for example, at least one of Al, Au, Cu, Cr, Fe, and Ni. 
         [0116]    If the first polarizing layer  120   a  is formed as a reflection type polarizing layer as described above, the first polarizing layer  120   a  can be directly formed on the first substrate  110  through a patterning process without any separate attachment process for attaching the first polarizing layer  120   a  to the first substrate  110 . Accordingly, the first polarizing layer  120   a  can be relatively easily formed.  FIG. 10  illustrates that the plurality of metal lines that constitute the first polarizing layer  120   a  are formed over substantially the entire first substrate  110 . That is, the plurality of metal lines is arranged in not only the display area DA but also the non-display area NDA. In this case, some of the light that is reflected from the plurality of metal lines arranged in the display area DA and some of the light that is reflected from the plurality of metal lines arranged in the non-display area NDA are re-incident to the first polarizing layer  120   a , and thus light use efficiency can be improved. On the other hand, the pattern of the first polarizing layer  120   a  is not limited to the pattern illustrated in  FIG. 10 . For example, a first polarizing layer  120   b  of  FIG. 11  or a first polarizing layer  120   c  of  FIG. 12  may be arranged on the first substrate  110  instead of the first polarizing layer  120   a . Hereinafter, this will be described in further detail. 
         [0117]    The first insulating layer  130   a  is similar to the first insulating layer  130  of  FIG. 5 . However, the first insulating layer  130   a  is formed to cover the first polarizing layer  130   a  on the first substrate  110 . 
         [0118]      FIG. 11  exemplifies that a first polarizing layer  120   b  includes a plurality of metal lines  121   b  arranged in the display area DA and metal pieces  122   b  arranged in the non-display area NDA. The plurality of metal lines  121   b  is the same as the plurality of metal lines that constitutes the first polarizing layer  120   a  of  FIG. 10 . The metal pieces  122   b  may be formed together with the plurality of metal lines  121   b , and may have the same height as the height of the plurality of metal lines  121   b . Since the first polarizing layer  120   b  is provided with metal pieces  122   b  having relatively large surface areas in the non-display area NDA, the light that is reflected from the plurality of metal lines  121   b  in the display area DA and the light that is reflected from the metal pieces  122   b  in the non-display area NDA can fall re-incident to the first polarizing layer  120   b , and thus the light use efficiency can be greatly improved. 
         [0119]      FIG. 12  exemplifies that a first polarizing layer  120   c  includes a plurality of metal lines  121   c  arranged on the first electrode PE, specifically on the first sub-electrode PE 1  and the second sub-electrode PE 2 , and metal pieces  122   c  arranged in the area outside that of the first electrode PE, including the non-display area NDA. The metal pieces  122   c  may be formed together with the plurality of metal lines  121   c , and may have the same height as the height of the plurality of metal lines  121   c . Since the first polarizing layer  120   c  has metal pieces  122   c  with relatively large surface areas outside the first electrodes PE, the light that is reflected from the plurality of metal lines  121   c  in the display area DA and the light that is reflected from the metal pieces  122   c  in the non-display area NDA can eventually fall re-incident to the first polarizing layer  120   c , and thus the light use efficiency can be greatly improved. 
         [0120]    Since the second display plate  200  of the display panel  11  has been described in detail with reference to  FIG. 5 , duplicate explanation thereof will be omitted. 
         [0121]    As described above, in the curved display device according to another embodiment of the present invention, since the first polarizing layer  120  is composed of the plurality of metal lines formed between the first substrate  110  and the liquid crystal layer LC, the first polarizing layer  120   a  can be more easily formed on the first substrate  110 , and light use efficiency can be heightened. Further, the light that maintains the polarization characteristic of the first polarizing layer  120   a  can be provided to the liquid crystal layer LC even if the first substrate  110  exhibits optical anisotropy. 
         [0122]    Accordingly, in the curved display device according to another embodiment of the present invention, in the case where the first polarizing layer is arranged outside the first substrate, the display of an unwanted image, for example the occurrence of a light leakage phenomenon in a black image, can be prevented. In particular, detrimental effects caused by light having polarization characteristics different from the polarization characteristic of the first polarizing layer, can be reduced. 
         [0123]    Next, a curved display device according to still another embodiment of the present invention will be described. 
         [0124]      FIG. 13  is a cross-sectional view of a different embodiment of a display panel constructed according to  FIG. 5 . 
         [0125]    Referring to  FIG. 13 , a curved display device according to this embodiment of the present invention has largely the same configuration as the configuration of the curved display device  50  of  FIG. 2 , except that display panel  12  is different from the display panel  10  of the curved display device  50 . Accordingly, explanation of the curved display device according to the present embodiment of the present invention will focus on the display panel  12 . 
         [0126]    The display panel  12  may include a first display plate  100   d  and a second display plate  200   a  that face each other. The first display plate  100   d  and the second display plate  200   a  may be bonded together by a sealant (not illustrated), as is known. A liquid crystal layer LC may be interposed between the first display plate  100   d  and the second display plate  200   a.    
         [0127]    The first display plate  100   d  of the display panel  12  is similar to the first display plate  100  of  FIG. 5 , and includes a first substrate  110 , a first polarizing layer  120   d , a first insulating layer  130   d , a gate line GL, a data line DL, a storage line SL, a reference line RL, a gate insulating layer  140 , a first thin film transistor TFT 1 , a second thin film transistor TFT 2 , a third thin film transistor TFT 3 , a protection layer  150 , and a first electrode PE. 
         [0128]    However, the first polarizing layer  120   d  is arranged outside the first substrate  110 . Accordingly, the first polarizing layer  120   d  polarizes light that is provided from the backlight unit  20  in a specific direction, and provides the polarized light to the first substrate  110 . Accordingly, if the first substrate  110  exhibits optical anisotropy, phase retardation may occur in the light that is polarized by the first polarizing layer  120   d  when the polarized light subsequently passes through the first substrate  110 . The phase-retarded light is then provided to the liquid crystal layer LC, and the polarization characteristic of the light that is provided to the liquid crystal layer LC may become different from the polarization characteristic of the light that is first polarized by the first polarizing layer  120   d . This may cause unwanted light to be included in the light that is polarized by the second polarizing layer  230   a . For example, in the case where the alignment of the liquid crystal molecules of the liquid crystal layer LC is controlled so that the curved display device displays a black image, a slight light leakage phenomenon may occur on the black image. The slight light leakage phenomenon may not be significant, but is still undesirable. 
         [0129]    The first polarizing layer  120   d  may be an absorption type polarizing layer or a reflection type polarizing layer like the first polarizing layer  120 .  FIG. 13  exemplifies a case where the first polarizing layer  120   d  is formed as an absorption type polarizing layer having an optical axis OA 1  (in  FIG. 6 ) of 0°. The first polarizing layer  120   d  may be arranged over substantially the entire first substrate  110 , but is not limited thereto. In some embodiments, the first polarizing layer  120   d  may be arranged to correspond only to the display area DA. 
         [0130]    The first insulating layer  130   d  is similar to the first insulating layer  130  of  FIG. 5 . However, the first insulating layer  130   d  is directly formed on the first substrate  110 . In some embodiments, the first insulating layer  130   a  may be omitted. 
         [0131]    The second display plate  200   a  of the display panel  12  is similar to the second display plate  200  of  FIG. 5 , and includes a second substrate  210 , a black matrix BM, a color filter CF, an overcoat layer  220 , a second electrode CE, and a second polarizing layer  230   a.    
         [0132]    The second polarizing layer  230   a  is formed between the second substrate  210  and the liquid crystal layer LC. For example, the second polarizing layer  230   a  may be formed between the second substrate  210  and the color filter CF. That is, the second polarizing layer  230   a  is formed on the second substrate  210  prior to other structures including the color filter CF, and may therefore not be affected by high temperature that is applied to form the other structures. Further, the second polarizing layer  230   a  may be arranged directly on the second substrate  210 , and may thus be relatively easily attached to the flat surface of the second substrate  210  or may be relatively easily manufactured on the flat surface of the second substrate  210 . 
         [0133]    The second polarizing layer  230   a  plays a similar role to the role of the polarizing layer  230  of  FIG. 5 . However, the second polarizing layer  230   a  is arranged between the second substrate  210  and the liquid crystal layer LC, and thus polarizes light that has passed through the liquid crystal layer LC, to provide polarized light to the second substrate  210 . Accordingly, the second polarizing layer  230   a  can polarize the light that is provided from the liquid crystal layer LC regardless of the phase retardation of the light that occurs due to the optical anisotropy of the second substrate  210 . Thus, in the case where the second polarizing layer is arranged outside the second substrate and polarizes the phase-retarded light, inclusion of unwanted light in the polarized light can be reduced. However, as described above, since the light that is polarized by the first polarizing layer  120   d  is provided to the liquid crystal layer LC in a state where the polarization characteristic of the polarized light is changed, some unwanted light may be included in the light that is polarized by the second polarizing layer  230   a , but not to a significant degree. 
         [0134]    The second polarizing layer  230   a  may be an absorption type polarizing layer or a reflection type polarizing layer.  FIG. 13  exemplifies a case where the second polarizing layer  230   a  is formed as an absorption type polarizing layer having an optical axis OA 2  (in  FIG. 7 ) of 90°. The second polarizing layer  230   a  may be arranged to cover substantially the entire surface of second substrate  210 , but is not limited thereto. In some embodiments, the second polarizing layer  230   a  may be arranged to correspond only to the display area DA. 
         [0135]    As described above, according to the current embodiment of the present invention, second polarizing layer  230   a  is formed between the second substrate  210  and the liquid crystal layer LC, and thus even if the optical anisotropy phenomenon occurs on the second substrate  210 , the second polarizing layer  230   a  can polarize light that is provided from the liquid crystal layer LC regardless of whether the second substrate  210  exhibits optical anisotropy. 
         [0136]    Accordingly, in the curved display device of this embodiment, when the second polarizing layer is arranged outside the second substrate, the display of an unwanted image, for example the occurrence of a light leakage phenomenon in a black image, which is caused by phase retardation due to the optical anisotropy of the second substrate, can be reduced. 
         [0137]    Next, a curved display device according to still another embodiment of the present invention will be described. 
         [0138]      FIG. 14  is a cross-sectional view of a different embodiment of a display panel constructed according to  FIG. 5 , and  FIG. 15  is a plan view of one pixel in the display panel of  FIG. 14 . 
         [0139]    Referring to  FIG. 14 , a curved display device according to still another embodiment of the present invention has the same configuration as that of the curved display device  50  of FIG.  2 , except that display panel  13  is different from the display panel  10  of the curved display device  50 . Accordingly, explanation of the curved display device according to this embodiment of the present invention will focus on the display panel  13 . 
         [0140]    The display panel  13  may include a first display plate  100   d  and a second display plate  200   b  that face each other. The first display plate  100   d  and the second display plate  200   b  may be bonded together by a sealant (not illustrated) in known manner. A liquid crystal layer LC may be interposed between the first display plate  100   d  and the second display plate  200   b.    
         [0141]    Since the first display plate  100   d  of the display panel  13  has been described in detail, duplicate explanation thereof will be omitted. 
         [0142]    The second display plate  200   b  of the display panel  13  is similar to the second display plate  200  of  FIG. 5 , and includes a second substrate  210 , a black matrix BM, a color filter CF, an overcoat layer  220 , a second electrode CE, and a second polarizing layer  230   b.    
         [0143]    Here, the second polarizing layer  230   b  is formed between the second substrate  210  and the liquid crystal layer LC. For example, the second polarizing layer  230   b  may be formed between the second substrate  210  and the color filter CF. That is, the second polarizing layer  230   b  is formed on the second substrate  210  prior to other structures including the color filter CF, and thus may not be affected by high temperature that is applied to form the other structures. Further, the second polarizing layer  230   b  may be arranged directly on the second substrate  210 , and may thus be relatively easily attached to the flat surface of the second substrate  210  or may be relatively easily manufactured on the flat surface of the second substrate  210 . 
         [0144]    The second polarizing layer  230   b  plays a similar role to the role of the polarizing layer  230  of  FIG. 5 . However, the second polarizing layer  230   b  is arranged between the second substrate  210  and the liquid crystal layer LC, and polarizes light that has passed through the liquid crystal layer LC so as to provide polarized light to the second substrate  210 . Accordingly, the second polarizing layer  230   b  can polarize light that is provided from the liquid crystal layer LC regardless of the phase retardation of the light that occurs due to the optical anisotropy of the second substrate  210 . Thus, relative to the case where the second polarizing layer is arranged outside the second substrate and polarizes the phase-retarded light, inclusion of unwanted light in the polarized light can be reduced. However, as described above, since the light that is polarized by the first polarizing layer  120   d  is provided to the liquid crystal layer LC in a state where the polarization characteristic of the polarized light is changed, some unwanted light may be included in the light that is polarized by the second polarizing layer  230   b , but not to a significant degree. 
         [0145]    The second polarizing layer  230   b  may be an absorption type polarizing layer which absorbs light that is not polarized in the direction that is perpendicular to the specific direction, or a reflection type polarizing layer which reflects light that is not polarized in the direction that is perpendicular to the specific direction.  FIGS. 14 and 15  exemplify a case where the second polarizing layer  230   b  is formed as a reflection type polarizing layer having an optical axis OA 2  of 90°. In this case, the second polarizing layer  230   b  may be arranged on the first electrode PE, specifically, on the first sub-electrode PE 1  and the second sub-electrode PE 2  only, and may include a plurality of metal lines that are perpendicular to the plurality of metal lines of  FIG. 9 . Accordingly, in the case where the second polarizing layer  230   b  is formed as a reflection type polarizing layer, a glare phenomenon caused by external light incident to the second polarizing layer  230   b  reflecting from the second polarizing layer  230   b  can be minimized. On the other hand, in the case where the plurality of metal lines that constitute the second polarizing layer  230   b  is arranged on the first electrode PE, specifically, on the first sub-electrode PE 1  and the second sub-electrode PE 2  only, the second polarizing layer  230   b  may be at the same level as the level of the black matrix BM. 
         [0146]    As described above, according to the curved display device of this embodiment of the present invention, since the second polarizing layer  230   b  is formed between the second substrate  210  and the liquid crystal layer LC, the occurrence of the glare phenomenon can be minimized, and even if the second substrate  210  exhibits optical anisotropy, the second polarizing layer  230   b  can polarize the light that is provided from the liquid crystal layer LC regardless of any resulting phase retardation from the second substrate  210 . 
         [0147]    Accordingly, in the curved display device of this embodiment of the present invention, in the case where the second polarizing layer is arranged outside the second substrate, the display of undesired image effects caused by phase retardation due to optical anisotropy of the second substrate, can be reduced. 
         [0148]    Next, a curved display device according to still another embodiment of the present invention will be described. 
         [0149]      FIG. 16  is a cross-sectional view of a different embodiment of a display panel constructed according to  FIG. 5 . 
         [0150]    Referring to  FIG. 16 , a curved display device according to this embodiment of the present invention has largely the same configuration as the configuration of the curved display device  50  of  FIG. 2 , except that display panel  14  is different from the display panel  10  of the curved display device  50 . Accordingly, explanation of the curved display device of this embodiment of the present invention will focus on the display panel  14 . 
         [0151]    The display panel  14  may include a first display plate  100   a  and a second display plate  200   b  that face each other. The first display plate  100   a  and the second display plate  200   b  may be bonded together by a sealant (not illustrated) in known manner. A liquid crystal layer LC may be interposed between the first display plate  100   a  and the second display plate  200   b.    
         [0152]    Since the first display plate  100   a  of the display panel  14  has been described in detail with reference to  FIG. 8 , duplicate explanation thereof will be omitted. 
         [0153]    Also, as the second display plate  200   b  of the display panel  14  has been described in detail with reference to  FIG. 14 , duplicate explanation thereof will be omitted. 
         [0154]    However, according to the display panel  14 , since the polarization characteristic of the light that is provided to the liquid crystal layer LC is the polarization characteristic of the light that is polarized by the first polarizing layer  120   a , and light that has passed through the liquid crystal layer LC is provided to the second polarizing layer  230   b  before being provided to the second substrate  210 , the light that has passed through the liquid crystal layer LC can be polarized by the second polarizing layer  230   b  without being affected by the optical anisotropy of the second substrate  210 . 
         [0155]    Accordingly, in the case where alignment of the liquid crystal molecules of the liquid crystal layer LC is controlled so that the curved display device displays a desired image, for example, a black image, the light that has passed through the liquid crystal layer LC does not pass through the second polarizing layer  230   b , and thus a black image can be displayed without light leakage. 
         [0156]    As described above, according to the curved display device of this embodiment of the present invention, since the first polarizing layer  120   a  is formed between the first substrate  110  and the liquid crystal layer LC and the second polarizing layer  230   b  is formed between the second substrate  210  and the liquid crystal layer LC, the light provided to the liquid crystal layer LC maintains the polarization characteristic imparted by first polarizing layer  120   a  even if the first substrate  110  exhibits optical anisotropy. Further, light that is provided from the liquid crystal layer LC can be polarized regardless of the optical anisotropy of the second substrate  210 . 
         [0157]    Accordingly, in the curved display device according to this embodiment of the present invention, the display of undesired image effects due to optical anisotropy of the second substrate  230 , can be minimized. 
         [0158]    Next, a curved display device according to still another embodiment of the present invention will be described. 
         [0159]      FIG. 17  is a cross-sectional view of a different embodiment of a display panel constructed according to  FIG. 5 . 
         [0160]    Referring to  FIG. 17 , a curved display device according to this embodiment of the present invention has largely the same configuration as the configuration of the curved display device  50  of  FIG. 2 , except that display panel  15  is different from the display panel  10  of the curved display device  50 . Accordingly, explanation of the curved display device according to this embodiment of the present invention will focus on the display panel  15 . 
         [0161]    The display panel  15  may include a first display plate  100   e  and a second display plate  200   b  that face each other. The first display plate  100   e  and the second display plate  200   b  may be bonded together by a sealant (not illustrated) as is known. A liquid crystal layer LC may be interposed between the first display plate  100   e  and the second display plate  200   b.    
         [0162]    The display panel  15  is similar to the first display plate  100   d  of  FIG. 14 , and includes a first substrate  110   e , a first polarizing layer  120   d , a first insulating layer  130   d , a gate line GL, a data line DL, a storage line SL, a reference line RL, a gate insulating layer  140 , a first thin film transistor TFT 1 , a second thin film transistor TFT 2 , a third thin film transistor TFT 3 , a protection layer  150 , and a first electrode PE. 
         [0163]    However, the first substrate  110   e  has a first thickness t 11  that is thinner than the first thickness t 1  of the first substrate  110   e  of  FIG. 14 . That is, the first thickness t 11  of the first substrate  110   e  may be thinner than the second thickness t 2  of the second substrate  210 . In this case, the first stress that occurs on the first substrate  110   e  due to fastening of the flat display panel  15  to the curved backlight unit  20  may be lower than the second stress that occurs on the second substrate  210 . 
         [0164]    Due to this, the amount of optical anisotropy of the first substrate  110   e  can be reduced. Accordingly, even if the first polarizing layer  120   d  is arranged outside the first substrate  110   e , phase retardation in the light that is polarized by the first polarizing plate  120   d  may not be significant even though the light subsequently passes through optically anisotropic substrate  110   e.    
         [0165]    Since the second display plate  200   b  of the display panel  15  has been described in detail, duplicate explanation thereof will be omitted. 
         [0166]    As described above, according to the curved display device of this embodiment of the present invention, the first stress that is generated in the first substrate  110   e  may be lower than the second stress in the second substrate  210  by making the first thickness t 11  of the first substrate  110   e  thinner than the second thickness t 2  of the second substrate  210 . 
         [0167]    Accordingly, in the curved display device according to this embodiment of the present invention, light provided to the liquid crystal layer has reduced phase retardation, due to the reduced optical anisotropy of the first substrate  110   e , allowing for a slim curved display device to be more effectively implemented. 
         [0168]    Next, a curved display device according to still another embodiment of the present invention will be described. 
         [0169]      FIG. 18  is a cross-sectional view of a different embodiment of a display panel constructed according to  FIG. 5 . 
         [0170]    Referring to  FIG. 18 , a curved display device according to this embodiment of the present invention has largely the same configuration as the configuration of the curved display device  50  of  FIG. 2 , except that display panel  16  is different from the display panel  10  of the curved display device  50 . Accordingly, explanation of the curved display device of this embodiment of the present invention will focus on the display panel  16 . 
         [0171]    The display panel  16  may include a first display plate  100   f  and a second display plate  200   c  that face each other. The first display plate  100   f  and the second display plate  200   c  may be bonded together by a sealant (not illustrated) in known manner. A liquid crystal layer LC may be interposed between the first display plate  100   f  and the second display plate  200   c.    
         [0172]    The display panel  16  is similar to the first display plate  100   a  of  FIG. 8 , and includes a first substrate  100 , a first polarizing layer  120   a , a first insulating layer  130   a , a gate line GL, a data line DL, a storage line SL, a reference line RL, a gate insulating layer  140 , a first thin film transistor TFT 1 , a second thin film transistor TFT 2 , a third thin film transistor TFT 3 , a second insulating layer  160   f , a black matrix BM, a color filter CF, a planarization layer  170   f , and a first electrode PE. 
         [0173]    In this embodiment, the second insulating layer  160   f  is formed on the first thin film transistor TFT 1 , the second thin film transistor TFT 2 , and the third thin film transistor TFT 3 . The black matrix BM and the color filter CF included in the second display plate  200  of  FIG. 8  are instead formed on the second insulating layer  160   f  of the first display plate  100   f . The planarization layer  170   f  is also formed on the first display plate  100   f  for planarization of the black matrix BM and the color filter CF. In this case, the black matrix BM may overlap the gate line GL, the data line DL, and the thin film transistors TFT 1 , TFT 2 , and TFT 3 . 
         [0174]    The second display plate  200   c  of the display panel  16  is similar to the second display plate  200  of  FIG. 8 , and includes a second substrate  210   c , a second polarizing layer  230 , and a second electrode CE. 
         [0175]    The second display plate  200   c  is thinner than the second display plate  200  of  FIG. 8 , as the second substrate  210   c  may be formed with a second thickness t 22  that is thinner than the first thickness t 1 . In this case, the second stress that occurs in the second substrate  210   c  due to fastening of the flat display panel  16  to the curved backlight unit  20  may be lower than the first stress that occurs on the first substrate  110 . 
         [0176]    Due to this, the amount of optical anisotropy occurring in the second substrate  210   c  can be reduced. Accordingly, even if the second polarizing layer  230  is arranged outside the second substrate  210   c , phase retardation in the light that passes through the second substrate  210   c  may not be significant. 
         [0177]    As described above, according to the curved display device according to this embodiment of the present invention, the second stress that is generated in the second substrate  210   c  can be made to be lower than the first stress in the first substrate  110  by making the second thickness t 22  of the second substrate  210   c  thinner than the first thickness t 1  of the first substrate  110 . 
         [0178]    Accordingly, in the curved display device according to this embodiment of the present invention, the light provided to the second polarizing layer  230  has reduced phase retardation due to the reduced optical anisotropy of the second substrate  210   c . Thus, a slim curved display device can be more advantageously implemented. 
         [0179]    Those skilled in the art will appreciate that many variations and modifications can be made to the preferred embodiments without substantially departing from the principles of the present invention. Therefore, the disclosed preferred embodiments of the invention are used in a generic and descriptive sense only and not for purposes of limitation. Any and all features of the various embodiments, disclosed or otherwise, may be mixed and matched in any manner, so as to create further embodiments also encompassed by the invention.