Patent Abstract:
This disclosure provides an array substrate for use in an IPS-LCD device which includes substantially zigzag-shaped pixel and common electrodes. The pixel electrodes and the common electrodes are connected with a connecting line and the common line, respectively. However, if each pixel and common electrode forms an acute angle with each connecting and common lines, liquid crystal molecules are strangely rotated and produce extraordinary domains in the intersection when the voltage is turned ON. Moreover, disclination occurs around the intersection. In order to overcome these problems, substantially sawtooth-shaped bases are employed of where the pixel and common electrodes meet the connecting and common lines, respectively. So each electrode forms an obtuse angle with each respective line, and thus the rotational direction of the liquid crystal molecules are the same in regions of the pixel area when the voltage is supplied. Accordingly, disclination is prevented, and the aperture ratio and the response characteristic are improved.

Full Description:
This application claims the benefit of Korean Patent Application No. 2000-54081, filed on Sep. 14, 2000, which is hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device implementing in-plane switching (IPS) where an electric field to be applied to liquid crystal molecules is generated in a plane parallel to a substrate.  
           [0003]    2. Discussion of the Related Art  
           [0004]    A liquid crystal display device uses the optical anisotropy and polarization properties of liquid crystal molecules to produce an image. Liquid crystal molecules have a definite orientational alignment as a result of their long, thin shapes. That orientational alignment can be controlled by an applied electric field. In other words, as an applied electric field changes, so does the alignment of the liquid crystal molecules. Due to the optical anisotropy, the refraction of incident light depends on the orientational alignment of the liquid crystal molecules. Thus, by properly controlling an applied electric field a desired light image can be produced.  
           [0005]    While various types of liquid crystal display devices are known, active matrix LCDs having thin film transistors and pixel electrodes arranged in a matrix are probably the most common. This is because such active matrix LCDs can produce high quality images at reasonable cost.  
           [0006]    Recently, liquid crystal display (LCD) devices with light, thin, and low power consumption characteristics are used in office automation equipment and video units and the like. Driving methods for such LCDs typically include a twisted nematic (TN) mode and a super twisted nematic (STN) mode. Although TN-LCDs and STN-LCDs have been put to practical use, they have a drawback in that they have a very narrow viewing angle. In order to solve the problem of narrow viewing angle, in-plane switching liquid crystal display (IPS-LCD) devices have been proposed. The IPS-LCD devices typically include a lower substrate where a pixel electrode and a common electrode are disposed, an upper substrate having no electrode, and liquid crystals interposed between the upper and lower substrates.  
           [0007]    A detailed explanation about operation modes of a typical IPS-LCD panel will be provided referring to FIGS.  1  to  3 .  
           [0008]    As shown in FIG. 1, upper and lower substrates  1  and  2  are spaced apart from each other, and a liquid crystal layer  3  is interposed therebetween. The upper and lower substrates  1  and  2  are called color filter substrate and array substrate, respectively. Pixel and common electrodes  4  and  5  are disposed on the lower substrate  2 . The pixel and common electrodes  4  and  5  are parallel with and spaced apart from each other. The pixel and common electrodes  4  and  5  apply a horizontal electric field  6  to the liquid crystal layer  3 . The liquid crystal layer  3  has a negative or positive dielectric anisotropy, and thus it is aligned parallel with or perpendicular to the horizontal electric field  6 , respectively.  
           [0009]    [0009]FIGS. 2A and 2B conceptually illustrate operation modes of a conventional IPS-LCD device. When there is no electric field between the pixel and common electrodes  4  and  5 , as shown in FIG. 2A, the long axes of the liquid crystal molecules maintain an angle from a line perpendicular to the parallel pixel and common electrodes  4  and  5 . Herein, the angle is 45 degrees, for example.  
           [0010]    On the contrary, when there is an electric field between the pixel and common electrodes  4  and  5 , as shown FIG. 2B, there is an in-plane horizontal electric field  6  parallel with the surface of the lower substrate  2  between the pixel and common electrodes  4  and  5 . The in-plane horizontal electric field  6  is parallel with the surface of the lower substrate  2  because the pixel and common electrodes  4  and  5  are formed on the lower substrate  2 . Accordingly, the liquid crystal molecules are twisted so as to align, for example, the long axes thereof with the direction of the horizontal electric field  6 , thereby the liquid crystal molecules are aligned such that the long axes thereof are parallel with the line perpendicular to the pixel and common electrodes  4  and  5 .  
           [0011]    By the above-mentioned operation modes and with additional parts such as polarizers and alignment layers, the IPS-LCD device displays images. The IPS-LCD device has wide viewing angles since the pixel and common electrodes are together placed on the lower substrate. Moreover, the fabricating processes of this IPS-LCD device are simpler than those of other various LCD devices.  
           [0012]    However in the IPS-LCD device, a color-shift which depends on the viewing angle still remains. It is already known that this color-shift cannot be acceptable for full color-image display. This color-shift is related to a rotational direction of the liquid crystal molecules under application of electric field when the applied voltage is greater than the threshold voltage. Moreover, this color-shift is caused by increasing or decreasing of an optical retardation (Δn·d) of the liquid crystal layer with viewing angle.  
           [0013]    For the sake of discussing the above-mentioned problem of the IPS-LCD device, with reference to FIG. 3, the specific pixel structure of the IPS-LCD device is employed and will be described in detail.  
           [0014]    As shown in FIG. 3, the pixel and common electrodes  7  and  8  have bend angle α. These bend electrode&#39;s structure allows the liquid crystal molecules  9  to rotate in opposite direction in each pixel when the voltage is supplied to the bend electrodes. Therefore, the bend electrodes  7  and  8  and the oppositely directed liquid crystal molecules  9  divide the pixel into two different regions with different viewing angle characteristics. And thus, the color-shift can be effectively compensated by this multi domain structure.  
           [0015]    However, when the voltage is turned ON, extraordinary domains appear around the bottom edges of driving electrodes. These extraordinary domains degrade the picture quality and reliability of the IPS-LCD device having the bend electrodes. Namely, disclination appears at the edges of the pixel areas, and thus this disclination manifests as positional non-uniformities in the transmittance of light.  
           [0016]    [0016]FIGS. 4A and 4B are enlarged partial plan views of pixel and common electrodes. These figures illustrate arrangement of the liquid crystal molecules and the electric field when the voltage is turned ON. As shown, a common electrode  11  is extended from a common line  23 , and a pixel electrode  21  is disposed parallel with the common electrode  11 . The common electrode  11  forms an acute angle with the common line  23  as depicted in a portion “A” of FIG. 4A while the pixel electrode  21  forms an obtuse angle with the common line  23  as shown in a portion “D” of FIG. 4A. When the voltage is supplied to the common and pixel electrodes  11  and  21 , the electric field occurs between the common and pixel electrodes  11  and  21 . However at this time, a distortion of the electric field appears around the acute and obtuse angels, the portions “A” and “D”. Thereupon, reverse rotational deformation is caused by this distortion of the electric field around the portions “A” and “D”.  
           [0017]    Referring to FIG. 4B, when the voltage is applied to the pair of electrodes  11  and  21 , the liquid crystal molecule  41  located in the parallel electric field area turns clockwise while the liquid crystal molecule  51  located in the distorted electric field area turns counterclockwise. So the orientation direction of the liquid crystal is different between the parallel electric field area and the distorted electric field area, and thus the disclination occurs in the distorted electric field area. This disclination causes a decrease in the aperture ratio, and a change of the orientation direction causes traces of the extraordinary domains. These features also affect response characteristic of the liquid crystal layer, and an afterimage phenomenon occurs in the display area  
         SUMMARY OF THE INVENTION  
         [0018]    Accordingly, the present invention is directed to an IPS-LCD device that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.  
           [0019]    An object of the present invention is to provide an array substrate for use in the IPS-LCD device having an increased aperture ratio.  
           [0020]    Another object of the present invention is to provide the array substrate for use in the IPS-LCD device which suppresses the traces of extraordinary domains and afterimage phenomenon.  
           [0021]    Another object of the present invention is to provide the array substrate for use in the IPS-LCD device which improves the response characteristics of the liquid crystal layer.  
           [0022]    In order to achieve the above object, the first preferred embodiment of the present invention provides an array substrate for use in an in-plane switching liquid crystal display device including a plurality of gate lines on a substrate; a plurality of data lines over the substrate, each data line being perpendicular to each gate line; a common line on the substrate, the common line being parallel with and spaced apart from the gate line; a plurality of common electrodes extended from the common line and elongated along the data line, wherein each common electrode has a plurality of bend portions, and wherein each common electrode has a sawtooth-shaped base in contacting part where each common electrode meets the common line in order to form an obtuse angle with the common line; a plurality of pixel electrodes spaced apart from and elongated along the common electrodes, wherein each pixel electrode has a plurality of bend portions and corresponds to each common electrode; a connecting line contacting one end of each pixel electrode, the connecting line electrically connecting pixel electrodes; a switching element electrically connected with the gate and data lines, the switching element supplying voltage to the pixel electrodes.  
           [0023]    Each pixel electrode has a sawtooth-shaped base in contacting part where each pixel electrode meets the connecting line, and makes an obtuse angle with the connecting line using the sawtooth-shaped base.  
           [0024]    The connecting line overlaps a portion of each gate line and comprises a storage capacitor with each gate line. One of the common electrodes elongates along the data line and electrically communicates with adjacent pixels.  
           [0025]    The common line crosses the one of bend portions of each common electrode, and electrically connects a plurality of common electrodes. Moreover, the common line elongates along the gate line and communicates with the other common lines that are located in the adjacent pixels.  
           [0026]    The present invention also provides, in another aspect, an array substrate for use in an in-plane switching liquid crystal display device including a gate line on a substrate; a data line over the substrate, the data line being perpendicular to the gate line; a common line being parallel with and spaced apart from the gate line; a plurality of common electrodes extended from the common line, wherein each common electrode has a zigzag shape and a sawtooth-shaped base, and wherein each common line forms an angle of greater than 90° with the sawtooth-shaped base; a connecting line being parallel with the gate line; a plurality of pixel electrodes extended from the connecting line, wherein each pixel electrode has a zigzag shape and a sawtooth-shaped base, and wherein each common line forms an angle of greater than 90° with the sawtooth-shaped base; and a switching element electrically connected with the gate and data lines, the switching element supplying voltage to the pixel electrodes.  
           [0027]    The aforementioned switching element is located in the crossing of the gate and data lines. This switching element includes a source electrode that is extended from the data line; a gate electrode that is extended from the gate line; a drain electrode that contacts one of the pixel electrodes through a drain contact hole; an active layer that is formed over the gate electrode and between the source and drain electrodes; and ohmic contact layers that are formed between the active layer and the source and drain electrodes.  
           [0028]    One of the pixel electrodes has a bend end portion over the drain electrode. This bend end portion overlaps one end of the drain electrode and contacts the drain electrode through the drain contact hole  
           [0029]    The connecting line overlaps a portion of the gate line, and the connecting line and the gate line comprise a storage capacitor. A plurality of the pixel electrodes and the connecting line can be made of a transparent conductive material. However, a plurality of the pixel electrodes and the connecting line can be made of an opaque metallic material.  
           [0030]    A plurality of the common electrodes and the common line can be made of a transparent conductive material. However, the plurality of the common electrodes and the common line can be made of an opaque metallic material.  
           [0031]    The present invention also provides, in another aspect, an array substrate for use in an in-plane switching liquid crystal display device including a gate line on a substrate; a data line over the substrate, the data line being perpendicular to the gate line, wherein each pair of gate and data lines defines a pixel area; a common line being parallel with and spaced apart from the gate line, wherein the common line is located in any region of the pixel area and elongates along the gate line; a plurality of common electrodes extended from the common line, wherein each common electrode has a zigzag shape and sawtooth-shaped base in the intersection where each common electrode crosses the common line, wherein each common line forms an angle of greater than 90° with the sawtooth-shaped base, and wherein one of the common electrodes elongates along the data line; a connecting line being parallel with the gate line; a plurality of pixel electrodes extended from the connecting line, wherein each pixel electrode has a zigzag shape and a sawtooth-shaped base, and wherein each common line forms an angle of greater than 90° with the sawtooth-shaped base; and a switching element electrically connected with the gate and data lines, the switching element supplying voltage to the pixel electrodes.  
           [0032]    One of the pixel electrodes has a sharply bent end portion over the switching element that is located in the crossing of the gate and data lines. This switching element includes a source electrode that is extended from the data line; a gate electrode that is extended from the gate line; a drain electrode that is the bent end portion of one pixel electrode; an active layer that is formed over the gate electrode and between the source and drain electrodes; and ohmic contact layers that are formed between the active layer and the source and drain electrodes.  
           [0033]    The drain electrode and the pixel electrodes can be separately formed on a different layers. Moreover, a substance of which the drain electrode is made can be different from that of the pixel electrodes. However, the data line, the connecting line, the pixel electrodes, and the source and drain electrodes can be made of the same material.  
           [0034]    The connecting line overlaps a portion of the gate line, and the connecting line and the gate line comprise a storage capacitor. And the common line and each common electrode intersect in one bend portion of each common electrode. Moreover, the common line is connected with the other common lines that are located in the adjacent pixel areas in order to form a mesh shape.  
           [0035]    One of the common electrodes is connected with the other common electrodes that are positioned in the adjacent pixel areas in order to form the mesh shape.  
           [0036]    A plurality of the pixel electrodes and the connecting line can be made of a transparent conductive material. However, the plurality of the pixel electrodes and the connecting line can be made of an opaque metallic material.  
           [0037]    A plurality of the common electrodes and the common line are made of a transparent conductive material. However, the plurality of the common electrodes and the common line are made of an opaque metallic material.  
           [0038]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0039]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.  
         [0040]    In the drawings:  
         [0041]    [0041]FIG. 1 is a conceptual cross sectional view illustrating a typical IPS-LCD panel;  
         [0042]    [0042]FIGS. 2A and 2B are conceptual perspective views illustrating operation modes of a conventional IPS-LCD device;  
         [0043]    [0043]FIG. 3 is a partial plan view illustrating bend electrodes of the conventional IPS-LCD device;  
         [0044]    [0044]FIGS. 4A and 4B are enlarged partial plan views of pixel and common electrodes according to the conventional IPS-LCD device;  
         [0045]    [0045]FIG. 5A is a plan view illustrating a pixel of an array substrate for use in an IPS-LCD device according to a first preferred embodiment of the present invention;  
         [0046]    [0046]FIG. 5B is a cross-sectional view taken along line V-V of FIG. 5A;  
         [0047]    [0047]FIGS. 6A and 6B are enlarged plan views of a portion “B” of FIG. 5A when the voltage is turned ON;  
         [0048]    [0048]FIG. 7A is a plan view illustrating a pixel of an array substrate for use in an IPS-LCD device according to a second preferred embodiment;  
         [0049]    [0049]FIG. 7B is a cross-sectional view taken along line VII-VII of FIG. 7A; and  
         [0050]    [0050]FIG. 8 is an enlarged plan view of a portion “C” of FIG. 7A. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0051]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0052]    [0052]FIG. 5A is a plan view illustrating a pixel of an array substrate for use in an IPS-LCD device according to a first preferred embodiment of the present invention, and FIG. 5B is a cross-sectional view taken along line V-V of FIG. 5A.  
         [0053]    As shown in FIG. 5A, a plurality of gate lines  121  are transversely disposed on a substrate  110  (see FIG. 5B). A common line  123  is spaced apart from the gate lines  121  and disposed parallel with the gate lines  121 . A plurality of data lines  161  that are spaced apart from each other are disposed across and perpendicular to the gate and the common lines  121  and  123 . Each pair of gate and data lines  121  and  161  defines a pixel area.  
         [0054]    Near the crossing of the gate and data lines  121  and  161 , gate and source electrodes  122  and  162  are positioned and electrically connected with the gate and data lines  121  and  161 , respectively. A drain electrode  163  is spaced apart from the source electrode  162  and overlaps one end of the gate electrode  122 . The source electrode  162  overlaps the other end of the gate electrode  122 . An active layer  140  is located over the gate electrode  122  and between the source and drain electrodes  162  and  163  and the gate electrode  122 .  
         [0055]    A connecting line  181  is disposed parallel with the gate line  121  and overlaps a portion of the gate line  121 . And thus the connecting line  181  and the gate line  121  comprise a storage capacitor. First and second pixel electrodes  182  and  183 , which extend from the connecting line  181 , are disposed in substantially zigzag shapes roughly perpendicular to the connecting line  181 , and thus the first and second pixel electrodes  182  and  183  communicate with the connecting line  181 . One end of the second pixel electrode  183  bends over the drain electrode  163  and overlaps one end of the drain electrode  163 . This end of the second pixel electrode  183  electrically contacts the drain electrode  163  through a drain contact hole  171 .  
         [0056]    First, second and third common electrodes  124 ,  125  and  126  that have substantially zigzag shapes are disposed parallel with the pixel electrodes  182  and  183 . And one end of each common electrode  124 ,  125  or  126  is electrically connected to the common line  123 . Each common electrode  124 ,  125  or  126  is spaced apart from the adjacent pixel electrodes  182  and  183 . Although FIG. 5A shows three common electrodes and two pixel electrodes, the number of the common and pixel electrodes depends on a space between electrodes and on an angle of the bend portions of each electrode.  
         [0057]    The common line  123 , the gate and data lines  121  and  161 , and the common electrodes  124 ,  125  and  126  are an opaque metal, while the pixel electrodes  182  and  183 , and the connecting line  181  are a transparent conductive material. Preferably, the opaque metal is selected from a group consisting of chromium (Cr), aluminum (Al), aluminum alloy (Al alloy), molybdenum (Mo), tantalum (Ta), tungsten (W), and antimony (Sb), and the like, while the transparent conductive material is indium tin oxide (ITO) or indium zinc oxide (IZO). However, the common line  123  and the common electrodes  124 ,  125  and  126  can be a transparent conductive material. Although not depicted in FIG. 5A, the gate line  121 , the gate electrode  122 , the common line  123 , and the common electrodes  124 ,  125  and  126  are covered by a gate insulation layer (see reference element  130  of FIG. 5) that is formed of silicon nitride (SiNx) or silicon oxide (SiO2).  
         [0058]    Still referring to FIG. 5A, portions of the pixel electrodes  182  and  183  contact the connecting line  181  and portions of the common electrodes  124 ,  125  and  126  also contact the common line  123 , and at least one of these portions has an obtuse angle between each line and each electrode. Such obtuse angle portions are shown, for example at the portion “B” of FIG. 6A, described by a dotted circle. Namely, each electrode makes the obtuse angle with each line by employing a sawtooth-shaped base of that driving electrode. That is, the pixel electrodes  182  and  183  intersect the connecting line  181  at an obtuse angle and the common electrodes  124 ,  125  and  126  intersect the common line  123  at an obtuse angle.  
         [0059]    Although not depicted in FIG. 5A, the data line  161  can have a substantially zigzag shape as if the abovementioned pixel and common electrodes do.  
         [0060]    Now referring to FIG. 5B, a fabricating process for the array substrate shown in FIG. 5A is provided. At first, the gate electrode  122  and the common electrodes  124  and  125  are formed on the substrate  110 . The gate line  121  of FIG. 5A is formed with the gate electrode  121  in the same layer, and thus the gate electrode  122  extends from the gate line  121 . If the gate electrode  122  and the common electrodes  124  and  125  are different materials, they are formed in different steps. Moreover, the common line  123  of FIG. 5A is formed with the common electrodes  124  and  125  in the same layer, and thus these common electrodes  124  and  125  that have substantially zigzag shapes extend from the common line  123 . After that, a gate insulation layer  130  is formed on the substrate  110  to cover the gate electrode  122  and common electrodes  124  and  125 . As mentioned before the gate insulation layer  130  is silicon nitride (SiNx) or silicon oxide (SiO2). Subsequently, an active layer  140  is formed on the gate insulation layer  130 , particularly over the gate electrode  122 . Ohmic contact layers  151  and  152  are formed on the active layer  140 , and thus the ohmic contact layers  151  and  152  are interposed between the active layer  140  and the source and drain electrodes that are formed in a later step. The active layer  140  includes an amorphous silicon layer (a-Si), while the ohmic contact layers  151  and  152  include a doped amorphous silicon layer (n+a-Si).  
         [0061]    The source and drain electrodes  162  and  163  are formed on the ohmic contact layers  151  and  152 , respectively, and on the gate insulation layer  130 . Those source and drain electrodes  162  and  163  are made of the same material as the gate electrode  122 . At this time, the data line  161  is formed together with the source electrode  162  such that the data line  161  is connected to the source electrode  162 . The source and drain electrodes  162  and  163  are spaced apart from each other and respectively overlap both ends of the gate electrode  122 .  
         [0062]    Thereafter, a passivation layer  170  is deposited over the entire surface of the substrate  110 , and then patterned to form the drain contact hole  171  that exposes a portion of the drain electrode  163 . The passivation layer  170  is made of silicon nitride (SiNx) or silicon oxide (SiO2). Next, the connecting line  181 , which overlaps the portion of the gate  15  line  121 , is formed on the passivation layer  170 . At this time, the first and second pixel electrodes  182  and  183  are simultaneously formed. And thus, one end of the second pixel electrode  183  contacts the drain electrode  163  through the drain contact hole  171 . These pixel electrodes  182  and  183  have substantially zigzag shapes and are parallel with the common electrodes  124  and  125 , as shown in FIG. 5A. Again, the pixel electrodes  182  and  183  are connected with the connecting line  181 . Although the connecting lines  181  and the pixel electrodes  182  and  183  are made of the transparent conductive material, such as ITO and IZO, as described above, they can be made of an opaque conductive material.  
         [0063]    Subsequently, although not shown in FIG. 5B, an orientation film of polyimide or photoalignment material is formed on the pixel electrodes and on the passivation layer, and rubbed by a fabric or patterned by light.  
         [0064]    [0064]FIGS. 6A and 6B are enlarged plan views of a portion “B” of FIG. 5A when the voltage is turned ON. These figures illustrate the structure of the electrodes and common lines according to the first embodiment. As shown in FIGS. 6A and 6B, the common electrode  124  has a sawtooth-shaped base in a contacting part between the common electrode  124  and the common line  123 . In other words, the common electrode  124  forms the angle of β, which is greater than 90°, with the sawtooth-shaped base that is a part of the common line  123 . Accordingly, the common electrode  124  has an obtuse angle (i.e., the angle of β) with the common electrode  123 . Here, when the voltage is applied to the common and pixel electrodes  124  and  182 , electric field  190  is then perpendicular to the common and pixel electrodes  124  and  182 . As shown FIG. 6B, not only liquid crystal molecules  211 , which are relatively far from the common line  123 , but also liquid crystal molecules  221 , which are relatively close to the common line  123 , turn clockwise, in contrast to the conventional art. Namely, the same rotational direction results in substantially the entire regions. Hence, the disclination does not appear, the traces of the extraordinary domains also do not appear, and the response characteristic of the liquid crystal layer is improved. Moreover, the afterimage phenomenon is not brought about in the display area.  
         [0065]    Now, the reference will be explained in detail to a second preferred embodiment referring to FIGS. 7A to  8 . According to the second embodiment, the common line also forms an obtuse angle with the common electrodes although these common line and common electrodes are formed in a mesh shape in order to decrease electrical resistance.  
         [0066]    [0066]FIG. 7A is a plan view illustrating a pixel of an array substrate for use in an IPS-LCD device according to the second preferred embodiment. As shown, a plurality of gate lines  121  are transversely disposed on a substrate  110  (see FIG. 7B). A plurality of data lines  161  that are spaced apart from each other are disposed across and perpendicular to the gate line  121 . Each pair of gate and data lines  121  and  161  defines a pixel area.  
         [0067]    Near the crossing of the gate and data lines  121  and  161 , gate and source electrodes  122  and  162  are positioned and electrically connected with the gate and data lines  121  and  161 , respectively. The source electrode  162  overlaps one end of the gate electrode  122 . A connecting line  181  is disposed parallel with the gate line  121  and overlaps a portion of the gate line  121 . And thus the connecting line  181  and the gate line  121  comprise a storage capacitor. First and second pixel electrodes  182  and  183 , which are extended from the connecting line  181 , are disposed in substantially zigzag shapes perpendicular to the connecting line  181 , and thus the first and second pixel electrodes  182  and  183  communicate with the connecting line  181 . One end of the second pixel electrode  183  bends over the gate electrode  122  and overlaps the other end of the gate electrode  122 . This end of the second pixel electrode  183  is spaced apart from the source electrode  162  and acts as a drain electrode  163 . However, the drain electrode  163  and the second pixel electrode  183  can be separately formed with different materials. When the drain electrode  163  is formed in a different fabricating step with different material, the pixel electrode can contact the drain electrode  163  through a drain contact hole (not shown). Moreover, an active layer  140  is located over the gate electrode  122  and between the source and drain electrodes  162  and  163 .  
         [0068]    A common line  127  is spaced apart from the gate lines  121  and transversely disposed parallel with the gate lines  121 . The common line  127  can be located in any region of the pixel area, and this common line  127  extends to the next pixels areas and is transversely connected with the other adjacent common lines, which are positioned in the next pixel areas, in order to form a mesh shape with one of common electrodes  124 .  
         [0069]    Still referring to FIG. 7A, first, second and third common electrodes  124 ,  125  and  126  that have substantially zigzag shapes are disposed roughly parallel with the pixel electrodes  182  and  183 , and extend from the common line  127 . Again, each common electrode  124 ,  125  or  126  is electrically connected to the common line  127  in a respective bend portion of each common electrode. Each common electrode  124 ,  125  or  126  is spaced apart from the adjacent pixel electrodes  182  and  183 . One of the common electrodes  124 ,  125  or  126 , for example the first common electrode  124 , extends along the data line  161  such that this common electrode is electrically connected to the other common electrodes that are located in adjacent upper and lower pixel areas. Thus, one of common electrodes  124  forms a mesh shape with the common line  127 . Although FIG. 7A shows three common electrodes and two pixel electrodes, the number of the common and pixel electrodes depends on a space between electrodes and on an angle of the bend portions of each electrode.  
         [0070]    In this second embodiment of the present invention, the common line  127 , the gate and data lines  121  and  161 , and the common electrodes  124 ,  125  and  126  can be an opaque metal. The pixel electrodes  182  and  183 , and the connecting line  181  can be a transparent conductive material if they are formed separately from the drain electrode  163 . Preferably, the opaque metal is selected from a group consisting of chromium (Cr), aluminum (Al), aluminum alloy (Al alloy), molybdenum (Mo), tantalum (Ta), tungsten (W), and antimony (Sb), and the like, while the transparent conductive material is indium tin oxide (ITO) or indium zinc oxide (IZO). However, the common line  127  and the common electrodes  124 ,  125  and  126  can be the transparent conductive material so as to provide a high aperture ratio. Although not depicted in FIG. 7A, the gate line  121 , the gate electrode  122 , the common line  127 , and the common electrodes  124 ,  125  and  126  are covered up with a gate insulation layer (see reference element  130  of FIG. 5) that is formed of silicon nitride (SiNx) or silicon oxide (SiO2).  
         [0071]    Still referring to FIG. 7A, portions at which the pixel electrodes  182  and  183  contact the connecting line  181  have obtuse angles between the connecting line  181  and each electrode  182  or  183 , as described in the first embodiment. Further, the intersections in which the common electrodes  125  and  126  cross the common line  127  also have obtuse angles, i.e., the portion “C” which is described by a dotted ellipse. Namely, each common electrode  125  or  126  forms an obtuse angle with the common line  127  by employing sawtooth-shaped bases of those driving electrodes.  
         [0072]    Although not depicted in FIG. 7A, the data line  161  can have a substantially zigzag shape as if the abovementioned pixel and common electrodes do.  
         [0073]    [0073]FIG. 7B is a cross-sectional view taken along line VII-VII of FIG. 7A. As shown, a fabricating process for the array substrate shown in FIG. 7A is provided. At first, the gate electrode  122  and the gate line  121  of FIG. 7A are formed on the substrate  110  in the same layer. And thus, the gate electrode  122  extends from the gate line  121 . After that, a gate insulation layer  130  is formed on the substrate  110  to cover the gate electrode  122  and the gate line  121  (see FIG. 7A). As mentioned before the gate insulation layer  130  is silicon nitride (SiNx) or silicon oxide (SiO2). Subsequently, an active layer  140  is formed on the gate insulation layer  130 , particularly over the gate electrode  122 . Ohmic contact layers  151  and  152  are formed on the active layer  140 , and thus the ohmic contact layers  151  and  152  are interposed between the active layer  140  and the source and drain electrodes that are formed in a later step. The active layer  140  includes an amorphous silicon layer (a-Si), while the ohmic contact layers  151  and  152  include a doped amorphous silicon layer (n+a-Si).  
         [0074]    Next, the source and drain electrodes  162  and  163  are formed on the ohmic contact layers  151  and  152 , respectively, and on the gate insulation layer  130 . Those source and drain electrodes  162  and  163  can be made of the same material as the gate electrode  122 . The source and drain electrodes  162  and  163  are then spaced apart from each other and respectively overlap the gate electrode  122 . At this time, the data line  161  is formed together with the source electrode  162  such that the data line  161  is connected to the source electrode  162 . Moreover, the first and second pixel electrodes  182  and  183 , which have substantially zigzag shapes, are formed on the gate insulation layer  130  when the source and drain electrodes  162  and  163  are formed. Thus, they can be made of the same materal. Simultaneously, the connecting line  181  is formed in the same layer such that the first and second pixel electrodes  182  and  183  contact the connecting line  181 . The connecting line  181  on the gate insulation layer  130  overlaps a portion of the gate line  121 , and thus these gate and connecting lines  121  and  181  comprise the storage capacitor, with the gate insulation layer  130  as a dielectric layer.  
         [0075]    At this point, since the drain electrode  163  is one end of the second pixel electrode  183  as described before, the drain contact hole (not shown) is not required. However, in case that the drain electrode  163  is formed separately from the pixel electrode and made of the different material from the pixel electrode, the step of fabrication needs additional steps and a drain contact hole is also required through a passivation layer that is formed in a later step.  
         [0076]    Thereafter, a passivation layer  170  is deposited over the entire surface of the substrate  110 . The passivation layer  170  is made of silicon nitride (SiNx) or silicon oxide (SiO2). As shown in FIG. 7B, the drain contact hole is not depicted, contrary to the first embodiment. Next, the common electrodes  124  and  125 , which have substantially zigzag shapes and are roughly parallel with the pixel electrodes  182  and  183 , are formed on the passivation layer  130 . Moreover, the common line  127  of FIG. 7A is formed with the common electrodes  124  and  125  in the same layer, and thus these common electrodes  124  and  125  extend from the common line  127 . The common line  127  and the common electrodes  124  and  125  can be formed of the transparent conductive material, such as ITO and IZO, or an opaque conductive material.  
         [0077]    Subsequently, although not shown in FIG. 7B, an orientation film of polyimide or photoalignment material is formed on the common electrodes and on the passivation layer, and rubbed by a fabric or patterned by light.  
         [0078]    [0078]FIG. 8 is an enlarged plan view of a portion “C” of FIG. 7A and illustrates the structure of the pixel electrodes and the common line according to the second embodiment. As shown, the common electrodes  125  and  126  have sawtooth-shaped bases at the intersections of the common electrodes  125  and  126  and the common line  127 . In other words, the common electrodes  125  and  126  form obtuse angles, which are greater than 90°, with the sawtooth-shaped bases, which are part of the common line  127 . Accordingly, as shown FIG. 6B, when the voltage is applied to the pixel and common electrodes, electric field is then perpendicular to the common and pixel electrodes. The rotational direction of the liquid crystal molecules should be the substantially same even regions near the intersection of the common electrodes  125  and  126  ad the common line  127 .  
         [0079]    Hence, as aforementioned, disclination does not appear in the intersection of the common electrodes and the common lines, traces of the extraordinary domains also do not appear, and the response characteristic of the liquid crystal layer is improved. Moreover, afterimage phenomenon is not brought about in the display area.  
         [0080]    Further, preferred embodiments of the present invention include the following advantages.  
         [0081]    First, since the in-plane switching liquid crystal display device (IPS-LCD) includes the substantially zigzag-shaped pixel and common electrodes, the IPS-LCD can have the wide viewing angle and can compensate color-shift.  
         [0082]    Second, since the pixel and common electrodes form obtuse angles with the connecting and common lines, the same rotational direction of the liquid crystal molecules under application of electric field, when the applied voltage is applied, should result near the intersection of the pixel electrodes and the connecting line and near the intersection of the common electrodes and the common line. Therefore, disclination does not occur, traces of the extraordinary domains also do not appear, and the response characteristic of the liquid crystal layer is improved. Moreover, the afterimage phenomenon is not brought about in the display area.  
         [0083]    It will be apparent to those skilled in the art that various modifications and variation can be made in the method of manufacturing a thin film transistor of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Technology Classification (CPC): 6