Patent Publication Number: US-2011051026-A1

Title: Photo-alignment agent and liquid crystal display device using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2009-0079469 filed in the Korean Intellectual Property Office on Aug. 26, 2009, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a photo-alignment agent and a liquid crystal display using the same. 
     (b) Description of the Related Art 
     One of the most widely used flat panel displays, a liquid crystal display (LCD) includes two display panels, each provided with field generating electrodes such as pixel electrodes and a common electrode, and a liquid crystal (LC) layer interposed therebetween. The LCD displays images by applying voltages to the field-generating electrodes on the display panel to generate an electric field across the LC layer. The electric field across the LC layer determines the orientation of LC molecules therein to adjust the polarization of incident light. 
     In the liquid crystal layer, an alignment layer is formed on the inner surfaces of the two display panels. The alignment layer aligns the liquid crystal molecules of the liquid crystal layer. If no voltage is applied to the field generating electrodes, the alignment layer aligns the liquid crystal molecules of the liquid crystal layer in a predetermined direction, while with the application of a voltage to the field generating electrodes, the liquid crystal molecules of the liquid crystal layer are rotated in the direction of the electric field. 
     In a conventional method for forming an alignment layer to align the liquid crystal, a rubbing method is used. In the rubbing method, a polymer layer, such as polyamide, is coated on a substrate such as glass, and the surface thereof is rubbed in a predetermined direction by using a fiber such as nylon or polyester. However, the rubbing method may generate minute dust and an electrostatic discharge (ESD), because of the friction between the fiber material and the polymer layer. The resulting dust and ESD may generate serious problems when manufacturing the liquid crystal panel. 
     To solve this problem, a light alignment method in which anisotropy is induced to the polymer layer, thus aligning the liquid crystal, has recently been researched. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY OF THE INVENTION 
     In one aspect, photo-reaction efficiency of a photo-alignment layer to improve transmittance is increased. 
     A photo-alignment agent according to the present invention includes a first alignment material without a photo-reactive group, a second alignment material including a photo-reactive group, and a photosensitizer mixed with the second alignment material. 
     The photosensitizer may be an additional material that does not chemically reacted with the second alignment material. 
     The photosensitizer may be one of compounds represented by Formula 1 to Formula 3. 
     
       
         
         
             
             
         
       
     
     The photosensitizer may be coupled to the second alignment material after baking the second alignment material. 
     The photosensitizer may include a functional group capable of reacting with the second alignment material. 
     The functional group may be one of an epoxy group, an amine group, a carboxylic acid group, and an alcohol group. 
     The photosensitizer may be one of compounds represented by Formula 4 and Formula 5. 
     
       
         
         
             
             
         
       
     
     Herein, X as a coupler may represent —O— or —S—, R may represent an alkyl having 1-15 carbon atoms, and Y may represent an oxirane, —OH, —NH 2 , or —COOH. 
     The photo-alignment layer may be formed by copolymerizing a first monomer including the photosensitizer and a second monomer including the photo-reactive group. 
     The first monomer may be one of compounds represented by Formula 6 and Formula 7. 
     
       
         
         
             
             
         
       
     
     Herein, X as a coupler may represent —O— or —S—, R may represent an alkyl having 1-15 carbon atoms, and Y may represent —O— or —COO—. 
     The photosensitizer may absorb a wavelength of 200-500 μm from a UV light source that is linearly polarized, thereby transmitting energy to the photo-reactive group. 
     The first alignment material and the second alignment material may form the alignment layer, and a ratio of a mol concentration of the second alignment material to a mol concentration of the first alignment material may be increased close to the surface of the alignment layer. 
     The first alignment material and the second alignment material may have a weight ratio of 5:95 to 50:50. 
     The second alignment material may include an imide group at a concentration of more than 75 mol %. 
     A photo-alignment agent according to the present invention includes a photo-alignment material that includes a main chain and a side chain having a photo-reactive group, and a photosensitizer, wherein the photo-reactive group includes a compound represented by Formula A. 
     
       
         
         
             
             
         
       
     
     Herein, A and B are independently one of cyclohexane, —CH 2 —, —C 2 H 4 —, dioxane, tetrahydropyran, benzene, naphthalene, and chromane, X and Y are independently single bonds or —C n H 2n —, where n is an integer of 1 to 12, and R is hydrogen or an alkyl group with 1 to 12 carbon atoms. 
     The C in the compound represented by Formula A may be one of compounds represented by Formula 10 to 13. 
     
       
         
         
             
             
         
       
     
     Herein, LP is a position connected to X. 
     The photosensitizer may be an additional material that does not react with the main chain or the photo-reactive group, and may be one of compounds represented by Formula 1 to Formula 3. 
     
       
         
         
             
             
         
       
     
     The photosensitizer may include a functional group coupled with the main chain after baking the second alignment material, and the functional group is one of an epoxy group, an amine group, a carboxylic acid group, and an alcohol group. 
     The photo-alignment layer may be formed by copolymerizing a first monomer including the photosensitizer and a second monomer including the photo-reactive group. 
     A liquid crystal display according to the present invention includes: a first substrate; a second substrate facing the first substrate; an alignment layer formed on at least one of the first substrate and the second substrate, the alignment layer including a first alignment material, a second alignment material including a photo-reactive group, and a photosensitizer mixed with the second alignment material; and a liquid crystal layer interposed between the first substrate and the second substrate. 
     The photosensitizer may absorb a wavelength of 200-500 μm from a UV light source that is linearly polarized, thereby transmitting energy to the photo-reactive group. 
     The photo-reactive group may include a compound represented by Formula A. 
     
       
         
         
             
             
         
       
     
     Herein, A and B are independently one of cyclohexane, —CH2-, —C2H4-, dioxane, tetrahydropyran, benzene, naphthalene, and chromane, X and Y are independently single bonds or —CnH2n-, and n is an integer of 1 to 12. 
     The photosensitizer may be an additional material that is not reacted with the second alignment material, and is one of compounds represented by Formula 1 to Formula 3. 
     
       
         
         
             
             
         
       
     
     The photosensitizer may include a functional group coupled with the main chain after baking the photo-alignment material, and the functional group may be one of an epoxy group, an amine group, a carboxylic acid group, and an alcohol group. 
     The alignment layer may be formed by copolymerizing a first monomer including the photosensitizer and a second monomer including the photo-reactive group. 
     A ratio of a mol concentration of the second alignment material to a mol concentration of the first alignment material may be increased close to the surface of the alignment layer. 
     The liquid crystal display may further include: a first signal line and a second signal line intersecting each other on the first substrate; a thin film transistor connected to the first signal line and the second signal line; a pixel electrode connected to the thin film transistor; and a common electrode formed on the second substrate. 
     The pixel electrode may include a first sub-pixel electrode and a second sub-pixel electrode. 
     The second sub-pixel electrode may include a first electrode piece disposed, in a layout view, above the first sub-pixel electrode, a second electrode piece disposed, in a layout view, under the first sub-pixel electrode and connected to the first sub-pixel electrode, and a plurality of bridge sections connecting the first electrode piece and the second electrode on, in a layout view, right and left sides of the first sub-pixel electrode. 
     As described above, according to the present invention, the pre-tilt angle is increased such that the transmittance may be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an equivalent circuit diagram of a pixel in a liquid crystal display according to an exemplary embodiment. 
         FIG. 2  is a layout view of a pixel electrode in a liquid crystal display according to an exemplary embodiment. 
         FIG. 3  is a schematic cross-sectional view of a liquid crystal display with the pixel electrode shown in  FIG. 2  taken along the III-III line thereof. 
         FIG. 4  is a layout view of a liquid crystal display according to an exemplary embodiment. 
         FIG. 5  is a layout view of a storage electrode line of the liquid crystal display shown in  FIG. 4 . 
         FIG. 6  is a layout view of the liquid crystal display shown in  FIG. 4  illustrating the directions that the aligned liquid crystal molecules are oriented over different regions on a pixel electrode thereof. 
         FIG. 7  is a cross-sectional view of the liquid crystal display shown in  FIG. 4  taken along the VII-VII line thereof. 
         FIG. 8  is a conceptual view of an alignment layer according to an exemplary embodiment. 
         FIG. 9  is a conceptual view of an alignment layer according to another exemplary embodiment. 
         FIG. 10  is a conceptual view of an alignment layer according to another exemplary embodiment. 
         FIG. 11  is a graph illustrating results of an analysis of an alignment layer according to an exemplary embodiment using a TOF-SIMS technique. 
         FIG. 12  is a graph illustrating results of an analysis of an alignment layer according to an exemplary embodiment using a TOF-SIMS technique. 
         FIG. 13  is a graph illustrating spot and afterimage degrees of a liquid crystal display with an alignment layer according to an exemplary embodiment. 
         FIG. 14  is a graph illustrating the afterimage degree of a liquid crystal display with an alignment layer according to an exemplary embodiment. 
         FIG. 15  is a graph illustrating a pre-tilt degree according to addition of a photosensitizer according to an exemplary embodiment. 
         FIG. 16  is a pixel picture of a photo-aligned cell including 4-direction domains. 
         FIG. 17  is a graph showing transmittance according to a pre-tilt degree. 
         FIG. 18  is a graph showing voltage holding ratio and ion density for a content of a photosensitizer according to an exemplary embodiment. 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS INDICATING PRIMARY ELEMENTS IN THE DRAWINGS 
       
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 3 liquid crystal layer 
                 11, 21 alignment layer 
               
               
                   
                 16 photo-reactive group 
                 17, 18 main chain 
               
               
                   
                 40 photosensitizer 
                 110, 210 substrate 
               
               
                   
                 191 pixel electrode 
                 270 common electrode 
               
               
                   
                 X vertical photo-alignment material 
                 Y alignment material 
               
               
                   
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. However, the present invention is not limited to exemplary embodiments described herein, and may be embodied in other forms. Rather, exemplary embodiments described herein are provided to describe the disclosed contents and to explain the ideas of the disclosure to a person of ordinary skill in the art. 
     In the drawings, the thicknesses of layers and regions are exaggerated for clarity. It is to be noted that when a layer is referred to as being “on” another layer or substrate, it can be directly formed on the other layer or substrate or it can be formed on the other layer or substrate with a third layer interposed therebetween. Like constituent elements are denoted by like reference numerals throughout the specification. 
       FIG. 1  is an equivalent circuit diagram of a pixel in a liquid crystal display according to an exemplary embodiment,  FIG. 2  is a layout view of a pixel electrode in a liquid crystal display according to an exemplary embodiment, and  FIG. 3  is a schematic cross-sectional view of a liquid crystal display with the pixel electrode shown in  FIG. 2  taken along the III-III line thereof. 
     Referring to  FIG. 1 , a liquid crystal display according to an exemplary embodiment includes a plurality of signal lines  121 ,  131 ,  171   a,  and  171   b,  and pixels PX connected thereto. 
     Referring to  FIG. 2  and  FIG. 3 , the liquid crystal display according to the present exemplary embodiment includes lower and upper display panels  100  and  200 , respectively, facing each other, and a liquid crystal layer  3  interposed between the two panels  100  and  200 . Pixel electrodes  191  (which includes  191   a,    191   b   1 , and  191   b   2 ) are formed on the lower display panel  100 , and a common electrode  270  is formed on the upper display panel  200 . 
     Alignment layers  11  and  21  are formed on the pixel and common electrodes  191  and  270 , respectively. A detailed description of the alignment layers  11  and  21  will be provided below. 
     The pixel electrode  191  includes first and second sub-pixel electrodes  191   a  and  191   b  that are separated from each other. 
     The signal lines  121 ,  131 ,  171   a,  and  171   b  are formed on the lower panel  100 , and include gate lines  121  for transmitting gate signals, a pair of data lines  171   a  and  171   b  for transmitting data voltages, and storage electrode lines  131 , to which storage voltages are applied. 
     The pixels PX each include a pair of sub-pixels PXa and PXb, each of which includes switching elements Qa and Qb, liquid crystal capacitors Clca and Clcb, and storage capacitors Csta and Cstb. 
     The switching elements Qa and Qb are three-terminal elements that include gate, source, and drain electrodes, and which are formed on the lower panel  100 . The gate electrode of the switching elements Qa and Qb is connected to the gate line  121 , the source electrode thereof is connected to the data lines  171   a  and  171   b,  and the drain electrode thereof is connected to the liquid crystal capacitors Clca and Clcb and the storage capacitors Csta and Cstb. 
     The liquid crystal capacitors Clca and Clcb are composed of the sub-pixel electrodes  191   a  and  191   b  of the lower display panel  100  and the common electrode  270  of the upper display panel  200 , which act as the two capacitor terminals, and the liquid crystal layer  3 , which acts as a dielectric, interposed between the two capacitor terminals,  191   a  and  191  band  270 . The sub-pixel electrodes  191   a  and  191   b  are connected to the switching elements Qa and Qb, and the common electrode  270  is formed on the entire surface of the upper display panel  200  so as to receive a common voltage Vcom. 
     The storage capacitors Csta and Cstb, which serve to assist the liquid crystal capacitors Clca and Clcb, are formed by interposing an insulator between the overlapped storage electrode line  131  and pixel electrodes  191   a  and  191   b.  The storage capacitors Csta and Cstb may be omitted as needed. 
     Referring to  FIG. 2 , the pixel electrode  191  is formed in the shape of a rectangle elongated in the vertical direction, and the first sub-pixel electrode  191   a  thereof is surrounded by the second sub-pixel electrode  191   b  thereof. 
     The first sub-pixel electrode  191   a  is shaped such that two identical rectangles, that are elongated in the vertical direction, are eccentrically (i.e., with offset centers) attached to each other in the horizontal direction along of the longer sides of each rectangle. Typically, the two identical rectangles are attached to each other so that their centers are offset by the amount required for the central, attached section of the rectangles, not including the protruding portions, to form a square. However, the length ratio of the horizontal side to the vertical side of the first sub-pixel electrode  191   a  may be altered in other ways. 
     The second sub-pixel electrode  191   b  surrounds the first sub-pixel electrode  191   a  with a gap  91 , which has an approximately uniform width. The sub-pixel electrode  191   b  includes an upper electrode portion  191   b   1  formed over the first sub-pixel electrode  191   a,  a lower electrode portion  191   b   2  formed below the first sub-pixel electrode  191   a,  and bridge portions  191   b   12  interconnecting the upper and lower electrode portions  191   b   1  and  191   b   2  on the left and right sides of the first sub-pixel electrode  191   a.    
     The second sub-pixel electrode  191   b  is greater in size than the first sub-pixel electrode  191   a,  and it is possible to control the length ratio of the vertical side of the first sub-pixel electrode  191   a  to the vertical side of the second sub-pixel electrode  191   b  to obtain a desired area ratio thereof. For example, the area of the second sub-pixel electrode  191   b  may be approximately two times the area of the first sub-pixel electrode  191   a.  In this case, the first sub-pixel electrode  191   a,  the upper electrode portion  191   b   1 , and the lower electrode portion  191   b   2  may all have the same area. 
     The liquid crystal layer  3  has negative dielectric anisotropy, and liquid crystal molecules thereof are vertically aligned. Polarizers (not shown) may be attached to the outer surfaces of substrates  110  and  210 , respectively. The polarization axes of the polarizers may be perpendicular to each other while being inclined with respect to the horizontal and vertical directions by about 45 degrees. 
     When there is no electric field generated at the liquid crystal layer  3 , that is, when there is no voltage difference between the pixel and common electrodes  191  and  270 , liquid crystal molecules  31  may be oriented perpendicular to the surface of the alignment layers  11  and  21 , or may be slightly inclined with respect thereto. 
     When a potential difference is applied between the pixel and common electrodes  191  and  270 , an electric field substantially perpendicular to the surface of the display panels  100  and  200  is generated across the liquid crystal layer  3 . Hereinafter, the pixel electrode  191  and the common electrode  270  will be collectively referred to as the “field generating electrodes.” The liquid crystal molecules  31  of the liquid crystal layer  3  rotate in response to the electric field such that the directors (i.e., the average orientation axes along the molecules, which is in the direction of the preferred orientation) thereof are oriented toward the direction perpendicular to the direction of the electric field. The degree of polarization of the light incident upon the liquid crystal layer  3  varies depending upon the degree of inclination of the liquid crystal molecules  31 . The variation in polarization is expressed by a variation in light transmittance through the polarizers so that the liquid crystal display can display images. 
     The direction that the liquid crystal molecules  31  are oriented depends upon the characteristics of the alignment layers  11  and  21 . For example, the direction the liquid crystal molecules  31  are oriented may be determined by, when forming the alignment layer, irradiating the alignment layers  11  and  21  with ultraviolet rays that differ in polarization direction to, or irradiating them in a slanted manner. 
     The liquid crystal molecules  31  of the liquid crystal layer  3  that are aligned over the pixel electrode  191  can have different orientation directions on different regions of the pixel electrode. The pixel electrode  191  may, for example, be partitioned into four regions: a left upper region D 1 ; a right upper region D 2 ; a right lower region D 3 ; and a left lower region D 4 . The partitioned regions D 1  to D 4  have substantially the same size and are adjacent to each other in the horizontal and vertical directions, with the horizontal and vertical center lines of the pixel electrode  191  forming the boundaries between regions. Typically, the orientation directions of the liquid crystal molecules placed in the regions D 1  to D 4  are angled with respect to each other by about 90 degrees, and the inclination directions of the liquid crystal molecules adjacent to each other are oriented in diagonally opposite directions. 
     The arrows in  FIG. 2  indicate the orientation directions of the liquid crystal molecules  31 , which are oriented at the left upper region D 1  to be in the right upper direction, at the right upper region D 2  to be in the right lower direction, at the right lower region D 3  to be in the left lower direction, and at the left lower region D 4  to be in the left upper direction. 
     However, the directions the liquid crystal molecules  31  are oriented in the four regions D 1  to D 4  are not limited to the above, and may be altered in various manners. Furthermore, the number of different directions the liquid crystal molecules  31  are oriented may be more or less than four. When the directions the liquid crystal molecules are oriented are diversified, the reference viewing angle of the liquid crystal display is increased. 
     Different voltages are applied to the first and second sub-pixel electrodes  191   a  and  191   b,  and based on the magnitude of the common voltage Vcom, the relative voltage of the first sub-pixel electrode  191   a  is generally higher than the relative voltage of the second sub-pixel electrode  191   b.  The inclination angle of the liquid crystal molecules is differentiated depending upon the intensity of the electric field. When the voltages of the first and second sub-pixel electrodes  191   a  and  191   b  are different from each other, the liquid crystal molecules  31  placed over the two sub-pixel electrodes  191   a  and  191   b  will have different inclination angles from each other. 
     Accordingly, the respective regions D 1  to D 4  of the liquid crystal layer  3  are divided into first sub-regions D 1   a,  D 2   a,  D 3   a,  and D 4   a  over the first sub-pixel electrode  191   a,  and second sub-regions D 1   b,  D 2   b,  D 3   b,  and D 4   b  over the second sub-pixel electrode  191   b.  As shown in  FIG. 3 , the voltage of the first sub-pixel electrode  191   a  is relatively high so that the liquid crystal molecules  31  of the first sub-regions D 1   a  to D 4   a  are inclined more than those of the second sub-regions D 1   b  to D 4   b.    
     Consequently, the two sub-pixels PXa and PXb have luminances which are different from each other, and the sum of luminance thereof becomes the luminance of the whole pixel PX. For this reason, the voltages applied to the two sub-pixel electrodes  191   a  and  191   b  should be established so as to make the luminance of the pixel PX have a target value. That is, the voltages applied to the two sub-pixel electrodes  191   a  and  191   b  are diverged from the image signal with respect to one pixel PX. 
     When the voltages of the first and second sub-pixel electrodes  191   a  and  191   b  are appropriately controlled, the image viewed from the lateral side approximates the image viewed from the frontal side as much as possible, thereby enhancing the lateral visibility. 
     A liquid crystal display according to another exemplary embodiment will now be described in detail with reference to  FIG. 4  to  FIG. 7 . 
       FIG. 4  is a layout view of a liquid crystal display according to an exemplary embodiment, and  FIG. 5  is a layout view of a storage electrode line of the liquid crystal display shown in  FIG. 4 .  FIG. 6  is a layout view illustrating the directions the aligned liquid crystal molecules are oriented over different regions of a pixel electrode of the liquid crystal display shown in  FIG. 4 , and  FIG. 7  is a cross-sectional view of the liquid crystal display shown in  FIG. 4  taken along the VII-VII line thereof. 
     Referring to  FIG. 4  to  FIG. 7 , the liquid crystal display according to the present exemplary embodiment includes a lower display panel or a thin film transistor array panel  100 , an upper display panel or a common electrode panel  200 , and a liquid crystal layer  3 . 
     First, the thin film transistor array panel  100  will be described in detail. 
     Gate conductors including gate lines  121  and storage electrode lines  131  are formed on an insulation substrate  110 . 
     The gate lines  121  proceed mainly in the horizontal direction, and each includes first and second gate electrodes  124   a  and  124   b,  which protrude upward from the gate line, and a wide end portion  129 . 
     The storage electrode lines  131  also proceed mainly in the horizontal direction, and each is interposed between two gate lines  121 . 
     Referring to  FIG. 5 , the storage electrode line  131  includes a storage electrode  137  formed in the shape of an opened quadrangular band, and connectors  136  connected thereto. The storage electrode  137  includes horizontal electrode portions  133 ,  134   a,  and  134   b  and vertical electrode portions  135 . The horizontal electrode portions  133 ,  134   a,  and  134   b  of the storage electrode  137  are larger in width than the vertical electrode portions  135  thereof. The horizontal electrode portions  133 ,  134   a,  and  134   b  include an upper electrode portion  133 , a right lower electrode portion  134   a,  and a left lower electrode portion  134   b.  One end of the upper electrode portion  133  and one end of the right lower electrode portion  134   a  are connected to each other via one of the vertical electrode portions  135 , and the opposite end of the upper electrode portion  133  and one end of the left lower electrode portion  134   b  are connected to each other via the other vertical electrode portion  135 . The opposite ends of the right lower electrode  134   a  and the left lower electrode  134   b  are spaced apart from each other by a distance so as to form the shape of an opened quadrangle. The connectors  136  are connected to approximately the centers of the vertical electrode portions  135 . 
     A gate insulating layer  140  is formed on the gate conductors  121  and  131 . 
     Referring to  FIG. 7 , first and second semiconductor stripes  151   a  and  151   b  are formed on the gate insulating layer  140  (second semiconductor stripe  151   b  is not shown in the drawings). The first and second semiconductor stripes  151   a  and  151   b  proceed mainly in the vertical direction, and include first and second protrusions  154   a  and  154   b  (shown in  FIG. 4 ) that protrude toward the first and second gate electrodes  124   a  and  124   b.    
     A first ohmic contact stripe  161   a  and a first ohmic contact island  165   a  are formed on the first semiconductor stripe  151   a.  The first ohmic contact stripe  161   a  has a protrusion  163   a,  and the protrusion  163   a  and the first ohmic contact island  165   a  face each other over the first protrusion  154   a  as a pair. 
     A second ohmic contact stripe (not shown) and a second ohmic contact island (not shown) are formed on the second semiconductor stripe  151   b.  The second ohmic contact stripe also has a protrusion (not shown), and the protrusion and the second ohmic contact island face each other over the second protrusion  154   b  as a pair. 
     A first data line  171   a  is formed on the first ohmic contact stripe  161   a,  and a first drain electrode  175   a  is formed on the first ohmic contact island  165   a.  A second data line  171   b  is formed on the second ohmic contact stripe, and a second drain electrode  175   b  is formed on the second ohmic contact island (shown in  FIG. 4 ). 
     Referring again to  FIG. 4 , the first and second data lines  171   a  and  171   b  proceed mainly in the vertical direction, and cross the gate lines  121  and the connectors  136  ( FIG. 5 ) of the storage electrode lines  131 . The first and second data lines  171   a  and  171   b  include first and second source electrodes  173   a  and  173   b,  which extend toward the first and second gate electrodes  124   a  and  124   b,  and wide end portions  179   a  and  179   b.    
     The first and second drain electrodes  175   a  and  175   b  each have one end placed over the first and second gate electrodes  124   a  and  124   b  while being partially surrounded by bent portions of the first and second source electrodes  173   a  and  173   b,  and extensions that extend upward from each one end thereof, respectively. The first ohmic contacts  161   a  and  165   a  exist only between the underlying first semiconductor  151   a  and the overlying first data line  171   a  and first drain electrode  175   a,  so as to lower the contact resistance therebetween. The second ohmic contact exists only between the underlying second semiconductor  151   b  and the overlying second data line  171   b  and second drain electrode  175   b,  so as to lower the contact resistance therebetween. The first semiconductor stripe  151   a  has substantially the same planar shape as the first data line  171   a,  the first drain electrode  175   a,  and the first ohmic contacts  161   a  and  165   a.  The second semiconductor stripe  151   b  has substantially the same planar shape as the second data line  171   b,  the second drain electrode  175   b,  and the second ohmic contact. However, the semiconductors  151   a  and  151   b  both have exposed portions that are not covered by the data lines  171   a  and  171   b  and the drain electrodes  175   a  and  175   b,  including exposed portions thereof which are between the source electrodes  173   a  and  173   b  and the drain electrodes  175   a  and  175   b.    
     A passivation layer  180  is formed on the first and second data lines  171   a  and  171   b,  the first and second drain electrodes  175   a  and  175   b,  and the exposed portions of the semiconductors  151   a  and  154   b.  The passivation layer  180 , which includes lower and upper layers  180   p  and  180   q,  is based on an inorganic insulating material, such as silicon nitride and silicon oxide. At least one of the lower and upper layers  180   p  and  180   q  may be omitted. 
     The passivation layer  180  has contact holes  182   a  and  182   b  exposing the end portions  179   a  and  179   b  of the data lines  171   a  and  171   b,  and contact holes  185   a  and  185   b  exposing the wide end portions of the drain electrodes  175   a  and  175   b.  The passivation layer  180  and the gate insulating layer  140  have a plurality of contact holes  181  in common that expose the end portions  129  of the gate lines  121 . 
     A color filter  230  is formed between the lower and upper layers  180   p  and  180   q.    
     The color filter  230  has through holes  235   a  and  235   b  corresponding to the contact holes  185   a  and  185   b  of the passivation layer  180 , and the through holes  235   a  and  235   b  are larger in size than the contact holes  185   a  and  185   b  of the passivation layer  180 . The color filter  230  further has a plurality of openings  233   a,    233   b,    234   a,  and  234   b  over the storage electrodes  137 . The openings  233   a  and  233   b  of the color filter  230  are formed over the upper electrode portion  133 , and the openings  234   a  and  234   b  of the color filter  230  are formed over the right lower electrode  134   a  and the left lower electrode  134   b,  respectively. 
     Pixel electrodes  191  and a plurality of contact assistants  81 ,  82   a,  and  82   b  are formed on the upper layer  180   q  of the passivation layer  180 . 
     As shown in  FIG. 4 , the pixel electrode  191  according to the present exemplary embodiment has substantially the same shape as that shown in  FIG. 2 . That is, the pixel electrode  191  includes first and second sub-pixel electrodes  191   a  and  191   b  spaced apart from each other with a gap  91  therebetween. 
     The gap  91  between the first and second sub-pixel electrodes  191   a  and  191   b  is overlapped with the storage electrode  137 . The storage electrode  137  prevents leakage of light between the first and second sub-pixel electrodes  191   a  and  191   b,  and simultaneously prevents texture that may be generated due to photo-alignment. In this case, the texture may exist on a portion the liquid crystal molecules meet each other between neighboring domains or in an edge of the pixel electrode. Also, the texture may be a portion displayed in black color when a voltage is applied. 
     The texture induced by photo-alignment is generated around the gap  91  in the orientation direction of the liquid crystal molecules. For example, as shown in  FIG. 6 , texture generation may occur at the left upper and right lower portions of the first sub-pixel electrode  191   a,  and the right upper and left upper portions of the second sub-pixel electrode  191   b.  Accordingly, when the left half of the first sub-pixel electrode  191   a  is oriented upward and the right half thereof is oriented downward, the texture-generating regions of the first sub-pixel electrode  191   a  linearly coincide with those of the second sub-pixel electrode  191   b.  Therefore, the texture-generating regions can be effectively covered only with a storage electrode  137  having a simplified and small-area structure. 
     The pixel electrode  191  is also overlapped with the storage electrode  137  so as to form a storage capacitor. That is, the first sub-pixel electrode  191   a  is overlapped with the upper electrode portion  133  and the right lower electrode portion  134   a  so as to form a storage capacitor Csta, and the second sub-pixel electrode  191   b  is overlapped with the upper electrode portion  133  and the left lower electrode  134   a  so as to form a storage capacitor Cstb. Because the pixel electrode  191  and the storage electrode  137  are overlapped with each other and have only the passivation layer  180  interposed between them, the capacitance of the storage capacitor is increased. 
     The first and second gate electrodes  124   a  and  124   b,  the first and second protrusions  154   a  and  154   b  of the first and second semiconductor stripes  151   a  and  151   b,  the first and second source electrodes  173   a  and  173   b,  and the first and second drain electrodes  175   a  and  175   b  form first and second thin film transistors Qa and Qb, and the first and second drain electrodes  175   a  and  175   b  are connected to the first and second sub-pixel electrodes  191   a  and  191   b  through the contact holes  185   a  and  185   b.    
     The contact assistants  81 ,  82   a,  and  82   b  are connected to the end portion  129  of the gate line  121  and the end portions  179   a  and  179   b  of the data lines  171   a  and  179   b  through the contact holes  181 ,  182   a,  and  182   b,  respectively. The contact assistants  81 ,  82   a,  and  82   b  serve to assist the adhesion of the end portion  129  of the gate line  121  and the end portions  179   a  and  179   b  of the data lines  171   a  and  171   b  to an external device such as a driver IC, and protect them. 
     The common electrode panel  200  will now be described in detail. 
     A plurality of light blocking members  220  are formed on an insulation substrate  210 , and a planarization layer  250  is formed on the light blocking members  220 . A common electrode  270  is formed on the planarization layer  250 . 
     Alignment layers  11  and  21  are formed on the surfaces of the thin film transistor array panel  100  and the common electrode panel  200  facing each other, respectively. 
     The alignment layers  11  and  21  according to an exemplary embodiment will now be described in detail with reference to  FIG. 7  to  FIG. 10 . 
       FIG. 8  is a conceptual view of an alignment layer according to an exemplary embodiment of the present invention, and  FIG. 11  is a graph illustrating results of an analysis of an alignment layer according to an exemplary embodiment by using the technique of time of flight secondary ion mass spectrometry (TOF-SIMS). 
     The alignment layers  11  and  21  are formed with a mixture of a vertical photo-alignment material X containing a vertical functional group in the side chain thereof, and a major alignment material Y generally used in the vertical alignment (VA) mode or the twisted nematic mode. The vertical photo-alignment material X and the major alignment material Y are put in a micro-phase separation (MPS) state. 
     The micro-phase separation of the alignment layers  11  and  21  is a structure generated when a mixture of the vertical photo-alignment material X and the major alignment material Y is applied to the pixel  191  and the common electrode  270 , and hardened. The alignment layers  11  and  21  with the micro-phase separation structure are irradiated with ultraviolet rays, and as a result, alignment layers  11  and  21  are formed by way of the reaction of a photo-reactive group. Irradiating the alignment layer  11  and  21  with ultraviolet rays generates very few side products in the alignment layers  11  and  21 , and the afterimages of the liquid crystal display are reduced. Furthermore, using ultraviolet irradiation to form the alignment layers  11  and  21  without performing a separate rubbing process reduces the production cost and increases the production speed. 
     The vertical photo-alignment material X is mainly formed on the side of the alignment layer surface that is closer to the liquid crystal layer  3 , and the major alignment material Y is mainly formed closer to the substrates  110  and  210 . Accordingly, the ratio of the molar concentrations of the vertical photo-alignment material X to the major alignment material Y is increased toward the surface of the alignment layers  11  and  21  that are closer to the liquid crystal layer  3 . The vertical functional group contained in the vertical photo-alignment material X may be present from the surface of the alignment layer to a depth of the alignment layer corresponding to roughly 20% of the entire thickness thereof, and in this case, the micro-phase separation structure that is formed may be relatively well-defined. 
     The vertical photo-alignment material X is a polymer material with a weight average molecular weight of roughly 1000 to 1,000,000, and is a compound having a main chain  17  ( FIG. 8 ) bonded with at least one side chain. The side chain includes (i) a flexible functional group, (ii) a thermoplastic functional group, (iii) a photo-reactive group  16 , and (iv) a vertical functional group, and may contain additional side chain groups. The main chain  17  may include at least one material including, but not limited to, polyimide, polyamic acid, polyamide, polyamicimide, polyester, polyethylene, polyurethane, polystyrene, etc. As the main chain  17  increasingly contains a cyclic structure, such as an imide group, the rigidity of the main chain becomes further reinforced. Accordingly, spots on the liquid crystal display that can be generated when the liquid crystal display is operated for a long period of time are reduced, and the stability with respect to the pre-tilt angle of the alignment layer is reinforced. Furthermore, if the main chain contains an imide group at a concentration of about 75 mol % or more, the spots are further reduced, and the stability with respect to the pre-tilt angle of the alignment layer is further reinforced. The pre-tilt angle is typically about 90 to 100 degrees. 
     The flexible functional group and/or the thermoplastic functional group can serve as functional groups that ease alignment of the side chains that are bonded to the main chain  17 . The flexible functional group and the thermoplastic functional group may contain a substituted or non-substituted alkyl or alkoxy group with a carbon number of roughly 3 to 20. 
     The photo-reactive group  16  is a functional group that directly causes a photo-dimerization reaction or a photo-isomerization reaction upon irradiation of the photo-alignment material X with ultraviolet rays. For example, the photo-reactive group  16  may contain, but is not limited to, at least one compound selected from an azo-based compound, a cinnamate-based compound, a chalcone-based compound, a coumarin-based compound, a maleimide-based compound, etc. 
     The vertical functional group is a functional group that moves the entire side chain in the vertical direction, i.e. approximately perpendicular to the direction of the main chain  17 , which is typically approximately parallel to the substrates  110  and  220 . The vertical functional group may contain an alkyl or alkoxy group-substituted aryl group with a carbon number of 3 to 10, or an alkyl or alkoxy group-substituted cyclohexyl group with a carbon number of 3 to 10. 
     The vertical photo-alignment material X may be prepared by polymerizing a monomer such as a diamine bonded with a side chain such as a flexible functional group, a photo-reactive group, and a vertical functional group with acid anhydride. Furthermore, the vertical photo-alignment material X may be prepared by adding a compound bonded with a thermoplastic functional group, a photo-reactive group, or a vertical functional group to a polyimide or polyamic acid. In this case, as the thermoplastic functional group is directly bonded to the polymer main chain, the side chain contains the thermoplastic functional group, photo-reactive group, vertical functional group, etc. 
     The major alignment material Y contains the main chain  18 , and has a weight average molecular weight thereof of about 10,000 to 1,000,000. Main chain  18  may include at least one material including, but not limited to, polyimide, polyamic acid, polyamide, polyamicimide, polyester, polyethylene, polyurethane, polystyrene, etc. When the major alignment material Y contains the imide group at a concentration of about 50 to 80 mol %, spots and afterimages of the liquid crystal display are further reduced. The major alignment material Y may contain a vertical functional group as a side chain bonded to the polymer main chain at a concentration of about 5 mol %. 
       FIG. 14  is a graph illustrating the degree of afterimages in a liquid crystal display as a function of the mol % of the vertical functional group contained in the major alignment material Y. As shown in  FIG. 14 , when the major alignment material Y contains the vertical functional group at a concentration of about 5 mol % or less, the afterimages of the liquid crystal display are reduced. Furthermore, when the major alignment material Y contains the vertical functional group at a concentration of about 2 mol % or less, the afterimages of the liquid crystal display are further reduced. 
     The weight ratio of the vertical photo-alignment material X to the major alignment material Y in the mixture may be in the range of about 5:95 to 50:50. If the content of the vertical photo-alignment material X in the mixture is about 50 wt % or less, the voltage holding rate (VHR) increases so that the afterimages of the liquid crystal display can be reduced. If the content of the vertical photo-alignment material X in the mixture is about 5 wt % or more, the pre-tilt angle uniformity is maintained so that spots on the liquid crystal display are reduced.  FIG. 13  is a graph illustrating the degree of afterimage and spots as a function of the weight percent (wt %) of the vertical photo-alignment material X, and the graph shows that when the content of the vertical photo-alignment material X in the mixture is about 10 to 30 wt %, the afterimage and spots on the liquid crystal display are further reduced. Furthermore, as the content of the vertical photo-alignment material X in the mixture becomes smaller, the amount of photo-reactive group is reduced, and thus even fewer unwanted byproducts are generated when the vertical photo-alignment material X is irradiated with ultraviolet rays. Consequently, the afterimages of the liquid crystal display are reduced and the reaction efficiency is heightened. As the content of the vertical photo-alignment material X in the mixture is reduced, the production cost is reduced. 
     The vertical photo-alignment material X and the major alignment material  18  each have surface tension of about 25-65 dyne/cm, respectively. The surface tension of the vertical photo-alignment material X is identical to, or smaller than, that of the major alignment material  18 , and in such case, the micro-phase separation structure becomes well-defined. 
     The graph shown in  FIG. 11  is produced based on the technique of TOF-SIMS, and the material composition of the target alignment layer is described below. 
     The vertical photo-alignment material X was formed by polymerizing a diamine where two side chains containing fluorine (F), an aryl group, and cinnamate are substituted, with acid dianhydride. In this instance, the content of the vertical photo-alignment material  17  was 20 wt %. The fluorine (F) content is used as an indicator for detecting the vertical photo-alignment material X. A polyimide that did not have a vertical functional group was used as the major alignment material Y at an amount of 80 wt %. An ITO thin film was formed on a substrate, and a mixture of the vertical photo-alignment material X and the major alignment material Y was printed on the ITO thin film. After the printed mixture was hardened, it was irradiated with linearly polarized ultraviolet rays to t form an alignment layer with a thickness of 1000 Å. 
     As illustrated in  FIG. 11 , the intensity of the fluorine (F) content in the vertical functional group was radically reduced over a very short period of time, and it turned out from the measurement that the fluorine content was no longer found above 91 Å of the total depth of the alignment layer from the surface thereof. Accordingly, it can be determined that as the vertical photo-alignment material X was formed up to a depth of 9% of the total depth of the layer from the surface of the alignment layer closest to the liquid crystal layer  3 , and the major alignment material Y was formed under the vertical photo-alignment material X, the micro-phase separation structure was well-defined. Furthermore, a liquid crystal display having the alignment layers was driven, and it was shown that few linear afterimages and surface afterimages were present in the liquid crystal display having the alignment layer. 
       FIG. 12  is a graph illustrating the results of an analysis of an alignment layer according to an exemplary embodiment by way of the technique of TOF-SIMS. The material composition of the target alignment layer was the same as that related to  FIG. 11  except that the content of the vertical photo-alignment material X was 10 wt % and the content of the major alignment material  18  was 90 wt %. In this case, the fluorine content was no longer present above 42 Å of total depth of the alignment layer from the surface thereof, and very few linear afterimages and surface afterimages were present. 
     Again referring to  FIG. 8 , a vertical photo-alignment material X according to an exemplary embodiment will be described. 
     The vertical photo-alignment material X according to the exemplary embodiment includes a photosensitizer  40 . The photosensitizer  40  may transmit absorbed energy when UV rays are used to irradiate the photo-reactive group  16 . In detail, the photosensitizer  40  may contain one of compounds having the below formulae, which can absorb a linearly polarized ultraviolet (LPUV) light source of a wavelength in the range of 200-500 μm, and then transmits the absorbed energy to the photo-reactive group  16 . 
     
       
         
         
             
             
         
       
     
     In this instance, the photosensitizer  40  does not chemically react with the main chain  17  of the vertical photo-alignment material X or the side chain including the photo-reactive group  16 , and is mixed with the vertical photo-alignment material X as an additional material. 
     The above-described photo-reactive group  16  contains, but it not limited to, at least one compound selected from an azo-based compound, a cinnamate-based compound, a chalcone-based compound, a coumarin-based compound, a maleimide-based compound, etc. The photo-reactive group  16  according to another exemplary embodiment may contain a compound represented by Formula A below. 
     
       
         
         
             
             
         
       
     
     Here, A and B are independently one of cyclohexane, —CH 2 —, —C 2 H 4 —, dioxane, tetrahydropyran, benzene, naphthalene, and chromane, X and Y are independently single bonds or —C n H 2n —, where n is an integer of 1 to 12. At least one —CH 2 — among —C n H 2n — may be substituted with —O—, benzene, cyclohexane, or —C═O—. However, it is preferable that —CH 2 — directly at the side of the benzene ring is not substituted with —C═O—. R may be hydrogen or an alkyl group of 1 to 12 carbon atoms, or an alkenyl group of 2 to 12 carbon atoms. Here, at least one of —CH 2 — may be substituted with —O—. 
     C may be one of compounds represented by Formula 10 to 13 below. 
     
       
         
         
             
             
         
       
     
     Here, the squiggly line “LP” designated in above Formula 10 is a position connected to X of Formula A. The squiggly lines in Formula 11-13 are also a position connected to X of Formula A. 
       FIG. 9  is a conceptual view of an alignment layer according to another exemplary embodiment. 
     Referring to  FIG. 9 , the photosensitizer  40  is a functional group  42  that is capable of reaction with the main chain  17  of the vertical photo-alignment material X. The functional group  42  may be connected to the photosensitizer  40  by a connector  41 . The functional group  42  may be one of an epoxy group, an amine group, a carboxylic acid group, and an alcohol group. For example, the photosensitizer  40  may be one of compounds represented by Formula 4 and Formula 5 below. 
     
       
         
         
             
             
         
       
     
     Here, X as a coupler may represent —O— or —S—, R may represent an alkyl having 1-15 carbon atoms, and Y may represent an oxirane, —OH, —NH 2 , or —COOH. 
     The photosensitizer  40  includes the functional group  42  such that if the vertical photo-alignment material is baked, the photosensitizer  40  may be coupled to the main chain  17  or the side chain of the vertical photo-alignment material X. Here, the photosensitizer  40  may be connected to the main chain  17  through the bridge L that is separated from the connector  41 . Consequently, the deterioration in which the photosensitizer  40  is lost due to a cleaning process or a baking process may be minimized. Also, the photosensitizer  40  that remains on the alignment layer, and then is eluted into to the liquid crystal layer after the manufacturing of the panel thereby functioning as the impurity, may be minimized. 
     The photo-reactive group  16  described through  FIG. 8  may be applied to the present exemplary embodiment. 
       FIG. 10  is a conceptual view of an alignment layer according to another exemplary embodiment. 
     Referring to  FIG. 10 , the photosensitizer  40  is connected to the main chain  17  through the connector  41 .  FIG. 10  is similar to the exemplary embodiment described with reference to with  FIG. 9 , however there is a method difference. According to the present exemplary embodiment, a first monomer including the photosensitizer  40  and a second monomer including the photo-reactive group  16  are copolymerized, thereby forming the vertical photo-alignment material X. 
     For example, the first monomer may be one of compounds represented by Formula 6 and Formula 7 below. 
     
       
         
         
             
             
         
       
     
     Here, X as a coupler may represent —O— or —S—, R may represent an alkyl having 1-15 carbon atoms, and Y may represent —O— or —COO—. 
     The first monomer including the photosensitizer  40  during the copolymerization may have a concentration ratio of 0.01 to 50.0 mol % with respect to the second monomer. 
     The photo-reactive group  16  described with reference to  FIG. 8  may be applied to the present exemplary embodiment. 
     Compared with the alignment layer that includes the vertical photo-alignment material as described with reference to  FIG. 9 , the photosensitizer  40  in the present exemplary embodiment has a uniform concentration in the alignment layer, and is positioned close to the photo-reactive group  16  such that the energy transmitting effect into the photo-reactive group  16  may be increased. Accordingly, the photo-reaction efficiency may be increased. 
       FIG. 15  is a graph illustrating a pre-tilt angle as a function of the addition of a photosensitizer according to an exemplary embodiment. 
     Referring to  FIG. 15 , a sample A is a test cell manufactured with an alignment layer that does not include the photosensitizer, and samples B and C are test cells manufactured with an alignment layer including the photosensitizer. The sample B and the sample C respectively use 5-nitroacenaphthene and 4-nitroaniline as the photosensitizer. The sample B and the sample C respectively use a photo-alignment layer to which the photosensitizer is added with the content of 0.2 wt % compared with the content of the vertical photo-alignment material X and the major alignment material Y. The concentration ratio of the vertical photo-alignment material X to he major alignment material Y is 20:80. For each sample, a thin film transistor substrate and a color filter substrate were printed with an alignment layer and then were obliquely irradiated with UV light. Then, the test cells were manufactured, including inserting the liquid crystal. The UV irradiation used to irradiate the alignment layer had conditions of an inclination angle of 40 degrees and 50 mJ, and 50 degrees and 50 mJ, as noted in  FIG. 15 . 
     The results of measuring the pre-tilt angle of the test cell manufactured through each condition, confirms that the pre-tilt angle of the sample added with the photosensitizer is increased by about 0.8 degrees to 1.0 degree in both conditions compared with the sample that does not have the photosensitizer added. 
       FIG. 16  is a pixel picture of a photo-aligned cell including 4-direction domains and  FIG. 17  is a graph showing transmittance according to a pre-tilt angle. 
     Referring to  FIG. 16 , textures in the liquid crystal of a crossed shape are present on the domain boundaries of 4-direction domains. As the textures are increased, the transmittance is decreased. Here, as the pre-tilt angle is low, the director of the liquid crystal may be aligned in the desired direction such that the width of the textures is reduced. Accordingly, as shown in  FIG. 17 , as the pre-tilt angle decreases, the transmittance increases. In the liquid crystal display according to an exemplary embodiment, the pre-tilt angle is additionally formed by adding the photosensitizer described with reference to  FIG. 15 , as the result, the transmittance may be increased. 
       FIG. 18  is a graph showing a voltage holding ratio and ion density as a function of the content of a photosensitizer according to an exemplary embodiment. 
     The photosensitizer may be added with the content of 0.001 to 10 wt % compared with the content of the vertical photo-alignment material X and the major alignment material Y. Referring to  FIG. 18 , when the content of the photosensitizer is about 0.2 wt %, the influence on the voltage holding ratio and the ion density is small, and when the content of the photosensitizer is about 0.8 wt %, the voltage holding ratio is largely reduced and the ion density is increased. Accordingly, considering the pre-tilt angle and the electrical characteristics, the photosensitizer with the content of 0.001 to 2 wt % may be added. 
     Table 1 represents an estimation of a surface afterimage of a test cell of which the content of the photosensitizer is variably 0 wt %, 0.2 wt %, and 0.8 wt %. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Voltage at which a surface 
               
               
                   
                 UV exposure 
                 afterimage does not appear 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Photosensitizer 0 
                 40 degrees/ 
                 2.8 
               
               
                 wt % 
                 50 mJ 
                 2.8 
               
               
                 Photosensitizer 0.2 
                 40 degrees/ 
                 2.7 
               
               
                 wt % 
                 50 mJ 
                 2.8 
               
               
                 Photosensitizer 0.8 
                 40 degrees/ 
                 2.8 
               
               
                 wt % 
                 50 mJ 
                 2.9 
               
               
                   
               
            
           
         
       
     
     After an electric field is applied 336 times at 50° C. to the test cell divided into four regions in the diagonal direction, and including a black region and a white region, the degree of surface afterimage is measured through the voltage at which the luminance difference between the black and white regions is not generated. The black afterimage is measured by relatively comparing the degree of luminance difference between the black and white regions. 
     The degree of surface afterimage in the case in which the content of the photosensitizer is increased to 0.8 wt % is also almost the same as before the addition, and it appears that the afterimage is slightly improved according to the addition of the photosensitizer in the case of the black afterimage. Accordingly, it is determined that the addition of the photosensitizer positively influences the black afterimages of the panel. 
     The above described photo-alignment of the alignment layer of the liquid crystal display was achieved using materials described according to an exemplary embodiment, however, the disclosure is not limited thereto. 
     A method of manufacturing a liquid crystal display according to an exemplary embodiment will now be described. However, overlapping descriptions will be omitted. 
     Thin film transistors including gate electrodes  124   a  and  124   b,  source electrodes  173   a  and  173   b,  drain electrodes  175   a  and  175   b,  and semiconductors  154   a  and  154   b  are formed on a substrate  110 . Lower and upper layers  180   p  and  180   q  are formed on the thin film transistors. A color filter  230  is formed between the lower and upper layers  180   p  and  180   q.  Pixel electrodes  191   a  and  191   b  and contact assistants  81 ,  82   a,  and  82   b  are formed on the upper layer  180   q.    
     A mixture of a vertical photo-alignment material X and a major alignment material Y is printed onto the pixel electrodes  191   a  and  191   b  and the contact assistants  81 ,  82   a,  and  82   b  by way of inkjet printing, and is hardened. The hardening may be performed in two steps. The mixture is pre-baked at about 70-80° C. for about 2 to 3 minutes to thereby remove a solvent therefrom, and is hardened at about 210° C. or more for about 10 to 20 minutes to thereby form a micro-phase separation structure. At this time, the vertical photo-alignment material X is formed at the upper side area, and the major alignment material Y is formed at the lower side area. 
     Thereafter, the substrate  110  is irradiated with ultraviolet rays that strike the surface in a vertical or inclined direction thereto. In this instance, as a rubbing process in a separate manner does not need to be conducted to form the alignment layer  11 , the production speed is increased and the production cost is reduced. Furthermore, the direction of irradiating ultraviolet rays may be altered using a mask so that multi-domains that are differentiated in the orientation of the pre-tilt angle direction may be formed. The ultraviolet rays may be partially polarized ultraviolet rays or linearly polarized ultraviolet rays. The wavelength of the ultraviolet rays may be about 270 to 360 nm, and the energy thereof may be about 10 to 5000 mJ. 
     Then, a liquid crystal layer  3  is formed on the alignment layer  11 . 
     Meanwhile, a light blocking member  220 , an overcoat  250 , and a common electrode  270  are sequentially formed on a substrate  210 . An alignment layer  21  is formed on the common electrode  270  in the same way as that used for forming the alignment layer  11  thereon. 
     The substrate  210  is disposed such that the alignment layer  21  formed on the substrate  210  contacts the liquid crystal layer  3 , and the two substrates  110  and  210  are combined with each other. 
     However, if the liquid crystal layer  3  is formed on the alignment layer  21  of the substrate  210 , the substrate  210  is disposed such that the alignment layer  11  formed on the substrate  110  contacts the liquid crystal layer  3 , and the two substrates  110  and  210  are combined with each other. 
     A common thin film deposition or photolithography-based patterning method may be used in order to form thin film transistors and electrodes. 
     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.