Abstract:
A liquid crystal display includes a first substrate, a first field generating electrode formed on the first substrate, a second substrate facing the first substrate, a second field generating electrode formed on the second substrate, and a liquid crystal layer formed between the first field generating electrode and the second field generating electrode, wherein at least one of the first field generating electrode and the second field generating electrode includes zinc aluminum oxide (ZAO), and the driving voltage is in a range of about 3.7 volts to about 5.6 volts for a transmittance of 90% (T 90 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2008-0013322 filed in the Korean Intellectual Property Office on Feb. 14, 2008, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Technical Field 
         [0003]    The present invention relates to a liquid crystal display. 
         [0004]    (b) Discussion of the Related Art 
         [0005]    Liquid crystal displays (LCDs) are one of the most widely used flat panel displays. A liquid crystal display has two display panels on which field generating electrodes are formed, and a liquid crystal layer that is interposed between the panels. In the liquid crystal display, a voltage is applied to the field generating electrodes so as to generate an electric field, and then the alignment of liquid crystal molecules of the liquid crystal layer is determined by the electric field. Accordingly, the transmittance of light passing through the liquid crystal layer is controlled. 
         [0006]    In the liquid crystal display, liquid crystals rotate due to an electric field generated between the pair of field generating electrodes to change the light transmittance, and images are displayed in response to the change of light transmittance. The pair of field generating electrodes may be a pixel electrode and a common electrode, the electric field generated between the pixel electrode and the common electrode is controlled by the pixel electrode, and the voltage of the pixel electrode is controlled by a switching element such as a thin film transistor (TFT). 
         [0007]    Since the liquid crystal display is a non-emissive element, light from inside or outside of the liquid crystal display is provided. For this purpose, a light source such as a backlight unit is provided on a rear surface of the thin film transistor array panel, and the light provided from the light source passes through the pixel electrode, the liquid crystal layer, and the common electrode, and is then transmitted to the outside. 
         [0008]    The light provided from the light source passes through several thin films of the liquid crystal display such that the degree of transmittance is decreased and a small amount of the light provided from the light source is finally transmitted. 
         [0009]    The transmittance of the light relates to the transmittance of each thin film including the pixel electrode and the common electrode. When the transmittance of each thin film is high, higher luminance may be obtained with the same or lower driving voltages, than when the transmittance of each thin film is low. 
       SUMMARY OF THE INVENTION 
       [0010]    The embodiments of the present invention realize higher luminances using lower driving voltages by increasing the transmittance of a liquid crystal display. 
         [0011]    A liquid crystal display according to an exemplary embodiment of the present invention includes a first substrate, a first field generating electrode formed on the first substrate, a second substrate facing the first substrate, a second field generating electrode formed on the second substrate, and a liquid crystal layer formed between the first field generating electrode and the second field generating electrode, wherein at least one of the first field generating electrode and the second field generating electrode includes zinc aluminum oxide (ZAO), and the driving voltage is in a range of about 3.7 volts to about 5.6 volts for a transmittance of 90% (T 90 ). 
         [0012]    The liquid crystal display may further include an alignment layer including silicon oxide (SiOx) formed on at least one of the first field generating electrode and the second field generating electrode. 
         [0013]    The driving voltage V 10  of the liquid crystal display may be in a range of about 0.9 volts to about 2.5 volts for a transmittance of 10% (T 10 ). 
         [0014]    The liquid crystal layer may include liquid crystal molecules having different optical anisotropy according to the intensity of the electric field between the first field generating electrode and the second field generating electrode. 
         [0015]    The liquid crystal molecule may exhibit optical isotropy in the absence of the electric field between the first field generating electrode and the second field generating electrode, and exhibit optical anisotropy under the application of the electric field between the first field generating electrode and the second field generating electrode. 
         [0016]    A total transmittance for a visible ray region of light may be in a range of about 89.5% to about 92.7%. 
         [0017]    A liquid crystal display according to an exemplary embodiment of the present invention includes a first substrate, a first field generating electrode formed on the first substrate, a second substrate facing the first substrate, a second field generating electrode formed on the second substrate, an alignment layer including silicon oxide (SiOx) formed on at least one of the first field generating electrode and the second field generating electrode, and a liquid crystal layer formed between the first field generating electrode and the second field generating electrode, wherein the driving voltage is in a range of about 3.7 volts to about 5.6 volts for a transmittance of 90% (T 90 ). 
         [0018]    The driving voltage V 10  of the liquid crystal display may be in a range of about 0.9 volts to about 2.5 volts for a transmittance of 10% (T 10 ). 
         [0019]    The liquid crystal layer may include liquid crystal molecules having different optical anisotropy according to the intensity of the electric field between the first field generating electrode and the second field generating electrode. 
         [0020]    The liquid crystal molecules may exhibit optical isotropy in the absence of the electric field between the first field generating electrode and the second field generating electrode, and exhibit optical anisotropy under the application of the electric field between the first field generating electrode and the second field generating electrode. 
         [0021]    A liquid crystal display according to an exemplary embodiment of the present invention includes a first substrate, a first field generating electrode formed on the first substrate, a second substrate facing the first substrate, a second field generating electrode formed on the second substrate, and a liquid crystal layer formed between the first field generating electrode and the second field generating electrode, wherein at least one of the first field generating electrode and the second field generating electrode includes zinc aluminum oxide, and the liquid crystal layer includes liquid crystal molecules having different optical anisotropy according to the intensity of the electric field between the first field generating electrode and the second field generating electrode. 
         [0022]    The driving voltage may be in a range of about 3.7 volts to about 5.6 volts with for a transmittance of 90% (T 90 ). 
         [0023]    The driving voltage V 10  of the liquid crystal display may be in a range of about 0.9 volts to about 2.5 volts for a transmittance of 10% (T 10 ). 
         [0024]    The liquid crystal molecules may represent optical isotropy in the absence of the electric field between the first field generating electrode and the second field generating electrode, and exhibit optical anisotropy under the application of the electric field between the first field generating electrode and the second field generating electrode. 
         [0025]    A total transmittance for a visible ray region of light may be in a range of about 89.5% to about 92.7%. 
         [0026]    According to an exemplary embodiment of the present invention, the transmittance may be increased, the driving voltage may be reduced to obtain the same luminance, and the luminance may be increased when using the same driving voltage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is an equivalent circuit diagram of a unit pixel in a liquid crystal display; 
           [0028]      FIG. 2  is a layout view of a liquid crystal display according to an exemplary embodiment of the present invention; 
           [0029]      FIG. 3  is a cross-sectional view of the liquid crystal display shown in  FIG. 2  taken along the lines III-III′-III″-III′″; 
           [0030]      FIG. 4  to  FIG. 6  are graphs showing the transmittances according to the kinds of the transparent electrodes and/or alignment layers for the visible ray region in the liquid crystal display according to exemplary embodiments of the present invention; 
           [0031]      FIG. 7  is a graph showing the relationship of driving voltage and transmittance according to kinds of transparent electrodes and alignment layers, according to exemplary embodiments of the present invention; and 
           [0032]      FIG. 8  is a graph showing the relationship of driving voltage and luminance according to kinds of transparent electrodes and alignment layers, according to embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0033]    The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways without departing from the spirit or scope of the present invention. 
         [0034]    In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. Like reference numerals may designate like elements throughout the specification. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. A liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to  FIG. 1  to  FIG. 3 . 
         [0035]      FIG. 1  is an equivalent circuit diagram of an unit pixel in a liquid crystal display,  FIG. 2  is a layout view of a liquid crystal display according to an exemplary embodiment of the present invention, and  FIG. 3  is a cross-sectional view of the liquid crystal display shown in  FIG. 2  taken along the lines III-III′-III″-III′″. 
         [0036]    Referring to  FIG. 1 , the liquid crystal display includes a plurality of signal lines  121  and  171 , and a plurality of pixels connected thereto and arranged in an approximate matrix shape. The liquid crystal display includes a lower panel  100  and an upper panel  200 , which are positioned opposite to each other, and a liquid crystal layer  3  formed therebetween. 
         [0037]    The signal lines  121  and  171  include a plurality of gate lines  121  for transferring gate signals (also referred to as scan signals), and a plurality of data lines  171  for transferring data signals. The gate lines  121  extend substantially in a row direction and are substantially parallel to each other, and the data lines  171  extend substantially in a column direction and are substantially parallel to each other. 
         [0038]    Each pixel includes a switching element Qp connected to the signal lines  121  and  171 , and a liquid crystal capacitor Clc and a storage capacitor Cst. The storage capacitor Cst can be omitted if necessary. 
         [0039]    The switching element Qp is a three-terminal element such as a thin film transistor (TFT), and is provided on the lower panel  100 , which includes a control terminal connected with the gate lines  121 , an input terminal connected with the data lines  171 , and an output terminal connected with the liquid crystal capacitor Clc and the storage capacitor Cst. 
         [0040]    The liquid crystal capacitor Clc has a pixel electrode  191  of the lower panel  100  and a common electrode  270  of a upper panel  200  as its two terminals, and the liquid crystal layer  3  between the two electrodes  191  and  270  serves as a dielectric material. The pixel electrode  191  is connected with the switching element Qp, and the common electrode  270  receives a common voltage Vcom. 
         [0041]    Next, the structure of the liquid crystal display of  FIG. 1  will be described in further detail with the reference to  FIG. 2  and  FIG. 3 . 
         [0042]    In connection with the lower panel  100 , a plurality of gate lines  121  for transmitting gate signals is formed on an insulating substrate  110 . Each gate line  121  includes a plurality of gate electrodes  124  projecting upward and an end portion  129  having a large area for connection with an external circuit. 
         [0043]    A gate insulating layer  140  is formed on the gate lines  121 , and a plurality of semiconductor stripes  151 , for example, made of hydrogenated amorphous silicon (abbreviated to “a-Si”) or polysilicon, are formed in a vertical direction on the gate insulating layer  140 . The semiconductor stripes  151  include a plurality of protrusions  154  extending toward the gate electrodes  124 . 
         [0044]    A plurality of ohmic contact stripes  161  and a plurality of ohmic contact islands  165 , for example, made of silicide or n+ hydrogenated amorphous silicon (a-Si) heavily doped with an n-type impurity such as phosphorus (P), are formed on the semiconductor stripes  151 . The ohmic contact stripes  161  include a plurality of protrusions  163  extending toward the protrusions  154  of the semiconductor stripes  151 , and the protrusions  163  and the ohmic contact islands  165  are disposed in pairs on the protrusions  154  of the semiconductor stripes  151 . 
         [0045]    A plurality of data lines  171  and a plurality of drain electrodes  175  are formed on the ohmic contact stripes  161 , the ohmic contact islands  165 , and the gate insulating layer  140 . 
         [0046]    The data lines  171  extending substantially in the longitudinal direction intersect the gate lines  121  and the storage electrode lines  131 , and transmit data signals. Each of the data lines  171  includes a plurality of source electrodes  173  branched out toward the gate electrodes  124 , and a source electrode  173  and a drain electrode  175  forming a pair are positioned opposite to each other on the gate electrode  124 . 
         [0047]    The gate electrode  124 , the source electrode  173 , and the drain electrode  175  form a thin film transistor (TFT) along with the semiconductor stripe  151 . The channel of the thin film transistor is located on the protrusion  154  of the semiconductor stripe  151  between the source electrode  173  and the drain electrode  175 . 
         [0048]    The semiconductor stripes  151  except for the channel regions between the source electrode  173  and the drain electrode  175  have substantially the same planar shape as the data lines  171  and the drain electrodes  175 . 
         [0049]    The ohmic contact stripes  161  are interposed between the semiconductor stripes  151  and the data lines  171 , and have substantially the same planar shape as the data lines  171 . The ohmic contact islands  165  are interposed between the semiconductor stripes  151  and the drain electrodes  175 , and have substantially the same planar shape as the drain electrode  175 . 
         [0050]    A passivation layer  180  is formed on the data lines  171  and the drain electrodes  175 . The passivation layer  180  may be made of an inorganic insulating material such as silicon nitride or silicon oxide, or an organic insulating material such as an acryl-based compound. 
         [0051]    The passivation layer  180  has a plurality of contact holes  185  and  182  respectively exposing the drain electrodes  175  and end portions  179  of the data lines  171 . The passivation layer  180  and the gate insulating layer  140  have a plurality of contact holes  181  respectively exposing the end portions  129  of the gate lines  121 . 
         [0052]    A plurality of pixel electrodes  191  and a plurality of contact assistants  81  and  82  are formed on the passivation layer  180 . 
         [0053]    The pixel electrodes  191  are physically and electrically connected to the drain electrodes  175  through the contact holes  185  and are supplied with data voltages from the drain electrodes  175 . 
         [0054]    The contact assistants  81  and  82  are connected through the contact holes  181  and  182  to the end portions  129  of the gate lines  121  and the end portions  179  of the data lines  171 , respectively. The contact assistants  81  and  82  enhance protection of and the adhesion of the exposed end portions  129  and  179  of the gate lines  121  and the data lines  171  to external apparatuses. 
         [0055]    The pixel electrodes  191  and the contact assistants  81  and  82  may be made of zinc aluminum oxide (ZAO). The zinc aluminum oxide is a transparent conductive oxide and may be in a form in which aluminum (Al) is coated on zinc oxide (ZnOx), for example in a ratio of zinc (Zn) to aluminum (Al) to oxygen (O) of 49:2:49. The zinc aluminum oxide has higher transmittance than indium tin oxide (ITO), the material used for conventional transparent electrodes. 
         [0056]    In connection with the the upper panel  200 , a plurality of light blocking members  220  that are separated from each other by a predetermined interval are formed on an insulating substrate  210 . The light blocking members  220  are also referred to as black matrixes and they prevent light leakage. 
         [0057]    A plurality of color filters  230 , an overcoat  250 , and a common electrode  270  are formed on the light blocking members  220 . 
         [0058]    The common electrode  270  also may be made of zinc aluminum oxide (zinc aluminum oxide, ZAO), like the pixel electrodes  191 . The zinc aluminum oxide is a transparent conductive oxide and may be in a form in which aluminum (Al) is coated on zinc oxide (ZnOx), for example in a ratio of zinc (Zn) to aluminum (Al) to oxygen (O) of 49:2:49. 
         [0059]    In the present exemplary embodiment, an example in which both of the pixel electrode  191  and the common electrode  270  are made of the zinc aluminum oxide (ZAO) will be described. Alternatively, only one of the pixel electrode  191  and the common electrode  270  may be made of zinc aluminum oxide (ZAO), and the other may be made of an indium oxide such as ITO or IZO. 
         [0060]    Alignment layers  11  and  21  are formed on the inner surfaces of the lower panels  100  and the upper panel  200 . 
         [0061]    The alignment layers  11  and  21  may be made of silicon oxide (SiOx). The silicon oxide has higher material stability and a higher transmittance than polyimide that is used as a material for conventional alignment layers. 
         [0062]    A liquid crystal layer  3  including a plurality of liquid crystal molecules  310  is formed between the lower panel  100  and the upper panel  200 . The liquid crystal layer  3  is in a state of negative dielectric anisotropy, and liquid crystal molecules  310  are aligned such that their long axes are substantially parallel to the surfaces of the panels  100  and  200  in the absence of an electric field, and are rearranged in a predetermined direction under the generation of an electric field between the common electrode  270  and the pixel electrode  191 . The liquid crystal molecules  310  may be subject to a Van der Waals interaction with alignment layers made of the silicon oxide to form a pretilt angle. 
         [0063]    As described above, according to an exemplary embodiment of the present invention, the pixel electrodes  191  and the common electrode  270  (referred to as “transparent electrodes”) are made of zinc aluminum oxide (ZAO). 
         [0064]    The zinc aluminum oxide (ZAO) has higher transmittance in the visible ray region such that the transmittance may be improved for the light provided from the light source such as a backlight, and accordingly higher luminance may be obtained with the application of the same driving voltage as in a conventional LCD and a lower driving voltage may result in the same luminance as when a higher driving voltage is applied in a conventional LCD. 
         [0065]    The transmittance and the driving voltage will be described in further detail with reference to  FIG. 4  to  FIG. 8 . 
         [0066]      FIG. 4  to  FIG. 6  are graphs showing the transmittances according to the kinds of the transparent electrodes and/or alignment layers for the visible ray region in the liquid crystal display according to embodiments of the present invention.  FIG. 7  is a graph showing the relationship of the driving voltage and the transmittance according to kinds of the transparent electrodes and the alignment layers, and  FIG. 8  is a graph showing the relationship of the driving voltage and the luminance according to kinds of the transparent electrodes and the alignment layers. 
         [0067]    Referring to  FIG. 4 , “A” indicates light transmittance of a liquid crystal display including a transparent electrode made of zinc aluminum oxide (ZAO), and “B” is light transmittance of a liquid crystal display including a transparent electrode made of ITO. 
         [0068]    As shown in the graph, the liquid crystal display A including the transparent electrode made of zinc aluminum oxide (ZAO) has higher transmittance than the liquid crystal display B including the transparent electrode made of ITO for the same wavelengths. In detail, the liquid crystal display B including the transparent electrode of ITO has total transmittance of about 87.4% in the visible ray region (about 400 to 700 nm), whereas the total transmittance is about 92.2% in the visible ray region in the case A of the zinc aluminum oxide (ZAO), which is higher. 
         [0069]    Referring to  FIG. 5 , “C” indicates transmittance according to wavelength of a liquid crystal display including a transparent electrode made of zinc aluminum oxide (ZAO) and an alignment layer made of polyimide, and “D” indicates transmittance according to wavelength of a liquid crystal display including a transparent electrode made of ITO and an alignment layer made of polyimide. 
         [0070]    As shown in the graphs, when the alignment layers made of polyimide are used, the liquid crystal display C including the transparent electrode of zinc aluminum oxide (ZAO) has higher transmittance than the liquid crystal display D including the transparent electrode of ITO for the same wavelengths In detail, the total transmittance is about 89.1% for the visible ray region in the case of the liquid crystal display D including the alignment layer of polyimide and the transparent electrode of ITO, whereas the total transmittance is about 92.7% for the visible ray region in the case of the liquid crystal display C including the alignment layer of polyimide and the transparent electrode of zinc aluminum oxide. 
         [0071]    Referring to  FIG. 6 , “E” indicates transmittance according to wavelength of a liquid crystal display including a transparent electrode made of zinc aluminum oxide (ZAO) and an alignment layer made of silicon oxide (SiOx), and “F” indicates transmittance according to wavelength of a liquid crystal display including a transparent electrode made of ITO and an alignment layer made of silicon oxide. 
         [0072]    As shown in the graph, the liquid crystal display E including the transparent electrode of zinc aluminum oxide (ZAO) and the alignment layer of silicon oxide has higher transmittance than the liquid crystal display F including the transparent electrode of ITO and the alignment layer of silicon oxide. In detail, the total transmittance is about 84.0% for the visible ray region in the case of the liquid crystal display F including the alignment layer of silicon oxide and the transparent electrode of ITO, whereas the total transmittance is about 89.5% for the visible ray region in the case of the liquid crystal display E including the alignment layer of silicon oxide and the transparent electrode of zinc aluminum oxide. 
         [0073]    The voltage characteristics of the above described liquid crystal displays with the transmittances “C”, “D”, “E”, and “F” will be described in further detail with reference to Table 1, and  FIG. 7  and  FIG. 8 . 
         [0074]    Table 1 shows the results of measuring the relationship of the driving voltage and the transmittance according to the kinds of transparent electrodes and alignment layers. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Driving voltage 
                 Driving voltage 
               
             
          
           
               
                 Transparent 
                 Alignment 
                   
                 Relative 
                   
                 Relative 
               
               
                 electrode 
                 layer 
                 V10 
                 fraction (%) 
                 V90 
                 fraction (%) 
               
               
                   
               
             
          
           
               
                 ITO 
                 Polyimide 
                 2.95 
                 100 
                 6.74 
                 100 
               
               
                   
                 (PI) 
               
               
                   
                 Silicon oxide 
                 2.42 
                 82 
                 5.56 
                 82.5 
               
               
                   
                 (SiO x ) 
               
               
                 ZAO 
                 Polyimide 
                 1.00 
                 33.9 
                 4.42 
                 65.6 
               
               
                   
                 (PI) 
               
               
                   
                 Silicon oxide 
                 0.93 
                 31.5 
                 3.79 
                 56.2 
               
               
                   
                 (SiO x ) 
               
               
                   
               
             
          
         
       
     
         [0075]    In Table 1, V 10  and V 90  are values of driving voltages respectively corresponding to the transmittances of 10% and 90% in the graph of  FIG. 7 , and a lower value indicates a lower driving voltage. The transmittance of 10% represents a black characteristic, and the transmittance of 90% represents a white characteristic. 
         [0076]    Referring to Table 1 and  FIG. 7 , when using alignment layers of the same material, the driving voltage of the liquid crystal display including the transparent electrode of zinc aluminum oxide (ZAO) required to achieve a certain transmittance or luminance is lower than that of the liquid crystal display including the transparent electrode of ITO. Also, when using transparent electrodes of the same material, the driving voltage of the liquid crystal display including the alignment layer of silicon oxide (SiOx) required to achieve a certain transmittance or luminance is lower than that of the liquid crystal display including the alignment layer of polyimide. 
         [0077]    The range of the driving voltage V 90  corresponding to the transmittance of 90% in the liquid crystal display including the transparent electrode of zinc aluminum oxide (ZAO) or the alignment layer of silicon oxide (SiOx), or the liquid crystal display including both, is about 3.7V to about 5.6V, thereby obtaining a lower driving voltage than when ZAO and/or SiOx is not used. Also, the range of the driving voltage V 10  corresponding to the transmittance of 10% in this liquid crystal display is about 0.9V to about 2.5V, thereby obtaining a lower driving voltage than when ZAO and/or SiOx is not used. 
         [0078]      FIG. 8  is a graph converting the transmittance of  FIG. 7  into luminance, and when using alignment layers of the same material, the driving voltage of the liquid crystal display including the transparent electrode of zinc aluminum oxide (ZAO) becomes lower to represent the same luminance, compared with the liquid crystal display including the transparent electrode of ITO. Also, when using the transparent electrodes of the same material, the liquid crystal display including the alignment layer made of silicon oxide (SiOx) has a lower driving voltage to represent the same luminance compared with the liquid crystal display including the alignment layer made of polyimide. 
         [0079]    Likewise, when using the alignment layers of the same material, the liquid crystal display including the transparent electrode of zinc aluminum oxide (ZAO) exhibits a higher luminance than that of the liquid crystal display including the transparent electrode of ITO when using the same driving voltage. Also, when using the transparent electrode of the same material, the liquid crystal display including the alignment layer of silicon oxide (SiOx) exhibits higher luminance than that of the liquid crystal display including the alignment layer of polyimide when using the same driving voltage. 
         [0080]    Accordingly, the transmittance may be increased, the driving voltage may be reduced to exhibit the same luminance, and the luminance may be increased for the driving voltage by using the transparent electrode of zinc aluminum oxide (ZAO) and/or the alignment layer of silicon oxide. 
         [0081]    A liquid crystal display according to an exemplary embodiment of the present invention will be described. 
         [0082]    The present exemplary embodiment includes substantially the same structure as the previous exemplary embodiment, however it includes different liquid crystal molecules  310  in the liquid crystal layer  3  compared with the embodiment described above. 
         [0083]    In the embodiment described above, the liquid crystal display including the liquid crystal molecules  310  having dielectric anisotropy was described. Alternatively, the liquid crystal display according to the present exemplary embodiment includes liquid crystal molecules  310  of which the optical characteristics are changed according to the electric field between the pixel electrode  191  and the common electrode  270 . 
         [0084]    The liquid crystal molecules  310  applied to the present exemplary embodiment exhibit optical isotropy in the absence of an electric field, and the optical anisotropy is exhibited under the application of an electric field between the pixel electrode  191  and the common electrode  270 , wherein the magnitude of the optical anisotropy is changed according to the intensity of the electric field. 
         [0085]    Accordingly, the liquid crystal molecules  310  are arranged between the two display panels  100  and  200  in a disorderly fashion without a specific direction in the absence of the electric field between the pixel electrode  191  and the common electrode  270 . During application of the electric field between the pixel electrode  191  and the common electrode  270 , the liquid crystal molecules  310  are arranged perpendicularly to the generation direction of the electric field. 
         [0086]    The liquid crystal molecules having the optical anisotropy change the alignment by rotation of the liquid crystal molecules according to the application of the electric field to display images, and the response speed is determined by the original viscosity of the liquid crystal molecules. In contrast, the optical anisotropic characteristics of the liquid crystal molecules according to an exemplary embodiment of the present invention is determined according to the application of the electric field, and the magnitude of the optical anisotropy is also changed according to the intensity of the electric field to display the images such that the original viscosity of the liquid crystal molecules is irrelevant. Accordingly, high response speed may be realized regardless of the original viscosity of the liquid crystal molecules. 
         [0087]    These liquid crystal molecules  310  may include a material having a liquid crystal phase that is referred to as a blue phase. The blue phase has a narrow temperature range between an isotropic phase and a cholesteric phase such that the optical isotropy is represented in the absence of the electric field and the optical anisotropy is represented under the application of the electric field. 
         [0088]    Like the above described exemplary embodiments, when the transparent electrode made of zinc aluminum oxide (ZAO) and/or the alignment layer made of silicon oxide are included when using the liquid crystal material of this blue phase, the transmittance may be increased, and simultaneously the high speed response characteristics may be realized. Furthermore, the driving voltage to represent the same luminance may be reduced and a higher luminance may be represented through the same driving voltage when compared with an LCD not using the ZAO and/or SiOx. 
         [0089]    While this invention has been described in connection with exemplary embodiments, it will be apparent to those skilled in the art that various modifications and changes may be made thereto without departing from the scope and spirit of the invention. Accordingly, it is to be understood that the invention is not limited to the disclosed embodiments, and is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.