Abstract:
A liquid crystal display device includes a plurality of liquid crystal cells on a substrate, a plurality of drive lines extending along first and second directions and connected to the plurality of liquid crystal cells, a plurality of pad lines extending from each of the plurality of drive lines at a first angle from one of the first and second directions, and a plurality of pads extending at the first angle and connected to each of the plurality of pad lines for supplying external drive signals.

Description:
[0001]    The present invention claims the benefit of Korean Patent Application No. P2000-87050 filed in Korea on Dec. 30, 2000, which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device and a fabricating method thereof. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, a liquid crystal display (LCD) controls light transmissivity of a matrix array pattern of liquid crystal cells in response to video signals, thereby displaying image data (pictures) corresponding to the video signals on a liquid crystal display panel. Accordingly, the LCD includes a liquid crystal display panel having liquid crystal cells arranged in an active matrix type, and driving integrated circuits (IC&#39;s) for driving the liquid crystal cells. 
         [0006]    The driving IC&#39;s are usually manufactured in chip form. The driving IC&#39;s are mounted on a tape carrier package (TCP) in case of a tape automated bonding (TAB) system and on a surface of a liquid crystal display panel in case of a chips-on-glass (COG) system. The driving IC&#39;s are connected with the corresponding signal lines that are disposed in a pixel area through electrode pads provided within the TCP and the liquid crystal display panel to supply driving signals. The electrode pad is electrically connected with a corresponding signal line in the pixel area through a pad line. 
         [0007]    In the liquid crystal display, a number of pixels disposed between adjacent pad lines is increased, thereby achieving a high resolution picture. Accordingly, the pad line that is connected between the electrode pad and the corresponding signal line in the pixel area is set to have a length that is different from adjacent pad lines in accordance with the location, as shown in  FIG. 1 . 
         [0008]    In  FIG. 1 , a conventional liquid crystal display device includes a plurality of pixels  52  formed in a pixel area, a gate pad part  54  connected with a gate driving circuit  57  for supplying signals to the pixels  52 , and a gate pad line  58  formed at an angle for connecting the pixels  52  with the gate pad part  54 . The pixels  52  display image data (pictures) in accordance with a corresponding signal supplied from a corresponding gate pad line  58 . 
         [0009]    A plurality of gate electrode pads  59  are formed in the gate pad part  54  for supplying a gate signal to the plurality of gate lines GL in the pixel area. The gate electrode pads  59  are disposed at an edge of a lower substrate  51  and are formed in a direction perpendicular to a panel edge  56  of the lower substrate  51 . Accordingly, the gate pad part  54  is electrically connected with a gate TCP  55  through the gate electrode pads  59 . A plurality of signal pads (not shown) are formed in a direction corresponding to the gate electrode pads  59  and are electrically connected with the gate electrode pads  59  along one side of the gate TCP  55 . The gate pad line  58  electrically connects the gate electrode pads  59  with the corresponding pixels  52 . The gate pad line  58  is wired at an angle with a fixed gradient for connecting the corresponding pixels  52  with the gate electrode pads  59  disposed in a direction perpendicular to the panel edge  56  of the lower substrate  51 . Accordingly, the pixels  52  in the pixel area receive the gate signal that is supplied from the gate driving circuit  57 , through a signal pad (not shown), the gate electrode pads  59  and the gate pad line  58 . 
         [0010]    Since the gate pad part  54  of the liquid crystal display device is disposed in a group in a direction perpendicular to the panel edge  56  of the lower substrate  51 , line resistance between adjacent gate pad lines  58  is unequal. Accordingly, the gate signals applied to the gate lines GL in the pixel area are distorted, thereby deteriorating picture quality. The line resistance difference between the gate pad lines  58  occurs in the same way at a data pad line between the data line DL of the pixel area and the data electrode pad (not shown) connected to the data driving circuit. Accordingly, the data signals applied to the data lines DL in the pixel area are distorted due to differences in the line resistance difference between adjacent data pad lines, thereby deteriorating picture quality. 
         [0011]    Such conventional liquid crystal display devices, particularly in the case of a high precision/high resolution such as a UXGA (where the number of pixels is 1600×1200), require more space since more lines are disposed in the limited pad width upon the pad line. Accordingly, the panel size is inevitably increased. 
       SUMMARY OF THE INVENTION 
       [0012]    Accordingly, the present invention is directed to a liquid crystal display device and fabricating method thereof that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. 
         [0013]    An object of the present invention is to provide a liquid crystal display device and a fabricating method thereof having an increased number of conductive lines in a limited pad width. 
         [0014]    Another object of the present invention is to provide a liquid crystal display device and a fabricating method thereof having a uniform line resistance between adjacent gate lines and data lines. 
         [0015]    Another object of the present invention is to provide a liquid crystal display device and a fabricating method thereof for preventing deterioration of picture quality. 
         [0016]    Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0017]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a liquid crystal display device includes a plurality of liquid crystal cells on a substrate, a plurality of drive lines extending along first and second directions and connected to the plurality of liquid crystal cells, a plurality of pad lines extending from each of the plurality of drive lines at a first angle from one of the first and second directions, and a plurality of pads extending at the first angle and connected to each of the plurality of pad lines for supplying external drive signals. 
         [0018]    In another aspect, a method of fabricating a liquid crystal display device having a matrix array of liquid crystal cells includes forming a drive line to extend along a first direction on a substrate, forming a pad line to extend from the drive line at a first angle from the first direction, forming a pad to extend at the first angle and connected to the pad line, forming an insulating film material on the substrate to cover the pad line and the pad, forming a contact hole in the insulating film to expose the pad, and forming an electrode pattern on the insulating film to connect to the pad through the contact hole. 
         [0019]    In another aspect, a liquid crystal display device includes a substrate, a plurality of orthogonal drive lines on the substrate, a plurality of pads extending at a first acute angle from an edge of the substrate, and a plurality of pad lines extending at the first angle and interconnected between each of the plurality of orthogonal drive lines and pads. 
         [0020]    In another aspect, a method of fabricating a liquid crystal display device includes forming a plurality of drive lines to extend along first and second directions on a substrate, forming a plurality of pad lines to extend from the plurality of drive lines at a first acute angle from an edge of the substrate, forming a plurality of pads to extend at the first acute angle and connect to the plurality of pad lines, forming an insulating film material on the substrate to cover the plurality of pad lines and the plurality of pads, forming a plurality of contact holes in the insulating film to expose the plurality of pads, and forming an electrode patterns on the insulating film to connect to the plurality of pads through the plurality of contact holes. 
         [0021]    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 DRAWINGS 
         [0022]    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. In the drawings: 
           [0023]      FIG. 1  shows a pad line of a conventional liquid crystal display device; 
           [0024]      FIGS. 2A to 2E  are cross sectional views showing an exemplary method of fabricating a liquid crystal display according to the present invention; and 
           [0025]      FIG. 3  shows an exemplary pad line of a liquid crystal display device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
         [0027]      FIGS. 2A to 2E  are cross sectional views representing steps of an exemplary method of fabricating a liquid crystal display according to the present invention. 
         [0028]    In  FIG. 2A , aluminum (Al) or copper (Cu), for example, may be deposited on a lower substrate  1  by a sputtering technique, for example, to form a metal thin film (not shown). The metal thin film may be patterned by photolithographic and wet etching processes, for example, to form a gate electrode  3  and a gate pad electrode  14  on the lower substrate  1 . The gate pad electrode  14  may be connected to a gate line GL (not shown) through a gate pad line (described below) and formed at an angle according to the location of the gate line GL. More specifically, the gate pad electrode  14  and the gate pad line (described below) may be formed with a large angle when a gate line is located at an upper or lower part of a panel, and may be formed with a small angle when a gate line is located at, or near a center part of the panel. 
         [0029]    In  FIG. 2B , a gate insulating film  9 , an active layer, and an ohmic contact layer may be sequentially formed on the lower substrate  1  by a chemical vapor deposition process, for example, to cover the gate pad electrode  14  and the gate electrode  3 . The gate insulating film  9  may be formed by depositing an insulating material of silicon nitride or silicon oxide, for example, and the active layer may be formed of undoped amorphous silicon or polycrystalline silicon, for example. In addition, the ohmic contact layer may be formed of amorphous silicon or polycrystalline silicon, for example, to which N-type or P-type impurities are introduced at high concentration. The ohmic contact layer and the active layer may be patterned by a photolithographic and anisotropic etching processes, for example, to form an ohmic contact layer  17  and an active layer  15  on a portion of the gate insulating film  9  corresponding to the gate electrode  3 . 
         [0030]    In  FIG. 2C , molybdenum (Mo) or a molybdenum alloy including MoW, MoTa, and MoNb, for example, may be deposited on the gate insulating film  9  to cover the ohmic contact layer  17  by chemical vapor deposition or sputtering processed, for example. The deposited metal or metal alloy makes an ohmic contact with the ohmic contact layer  17 . The metal or metal alloy may be patterned by a photolithographic process, thereby forming a source electrode  5  and a drain electrode  7 . In addition, a data pad electrode  24  may be connected to a data line DL (not shown) through a data pad line (described below), and formed at an angle in accordance with a location of the data line DL (not shown). While patterning the source and drain electrodes  5  and  7 , a portion of the ohmic contact layer  17  corresponding to the gate electrode  3  located between the source and drain electrodes  5  and  7  is also patterned, thereby exposing a portion of the active layer  15  that will become a channel. 
         [0031]    In  FIG. 2D , an inorganic insulating material such as silicon nitride (SiNx) and silicon oxide, for example, or an organic insulating material, having a small dielectric constant, such as an acrylic organic compound, Teflon7, benzocyclobutene (BCB), Cytop7, and perfluorocyclobutane (PFCB), for example, may be deposited on the gate insulating layer  9  to cover the gate pad electrode  14 , the data pad electrode  24 , and the source and drain electrodes  5  and  7 , thereby forming a protective layer  21 . The protective layer  21  may be patterned by a photolithographic process, for example, to expose portions of the drain electrode  7 , the gate pad electrode  14 , and the data pad electrode  24 , thereby forming first to third contact holes  19   a ,  19   b , and  19   c.    
         [0032]    In  FIG. 2E , transparent conductive material such as indium-tin-oxide (ITO), indium-zinc-oxide (IZO), and indium-tin-zinc-oxide (ITZO), for example, may be deposited on the protective layer  21  to form a pixel electrode  23  on the protective layer  21 . The pixel electrode  23  may electrically contact the data pad electrode  24  through the first contact hole  19   a , the drain electrode  7  through the second contact hole  19   b , and the gate pad electrode  14  through the third contact hole  19   c . The data pad electrode  24  may be connected to a data line (not shown) of a pixel area through a data pad line (not shown) contacting the first contact hole  19   a . The gate pad electrode  14  may be connected to the gate line (not shown) of the pixel area through a gate pad line (not shown) contacting the third contact hole  19   c.    
         [0033]      FIG. 3  shows an exemplary pad line of a liquid crystal display device according to the present invention for connecting the gate line GL with the gate pad electrode  14  (in  FIG. 2E ) and the data line DL with the data pad electrode  24  (in  FIG. 2E ) in the pixel area. 
         [0034]    In  FIG. 3 , a liquid crystal display device may include pixels  32  formed in a pixel area  31 , an angled gate pad part  34  connected with a gate driving circuit  37  for supplying gate signals to the pixels  32 , and an angled gate pad line  38  for connecting the gate pad part  34  to the pixels  32 . The pixels  32  display image data (a picture) in response to gate signals supplied from corresponding gate pad lines  38 . 
         [0035]    A plurality of gate electrode pads  39  may be formed in the gate pad part  34  for supplying the gate signals to a plurality of gate lines GL of the pixel area  31 . The gate electrode pads  39  may be disposed at an edge of the lower substrate  1  corresponding to a location of the gate line GL of the pixel area  31 . Specifically, the gate pad electrode  14  and the gate pad line (not shown) may be formed at a relatively large angle in a case where a gate line GL is located at an upper or lower part of a display panel, and may be formed at a relatively small angle in a case wherein a gate line GL is located at, or near a center portion of the display panel. Consequently, the gate pad part  34  may be connected to a gate TCP  35  through the gate electrode pads  39 . 
         [0036]    A plurality of gate signal pads (not shown) may be formed along a direction corresponding to the gate electrode pads  39  and may electrically contact the gate electrode pads  39 . In other words, the gate signal pads (not shown) may be formed at an angle equal to the angle of the gate electrode pads  39  for preventing a short circuit between adjacent gate electrode pads  39 . The gate pad lines  38  connect the gate electrode pads  39  to corresponding pixels  32  for supplying the gate signals through the gate electrode pads  39  of the gate pad part  34 . The gate pad lines  38  may be formed parallel to the direction of the gate electrode pads  39 . Thus, the pixels  32  receive the gate signals from the gate driving circuit  37 . 
         [0037]    In  FIG. 3 , the liquid crystal display device may include a data pad part  44  connected to a data driving circuit  47  for supplying data signals to the pixels  32 , and an angled data pad line  48  for connecting the data pad part  44  to the pixels  32 . 
         [0038]    A plurality of data electrode pads  49  may be formed for supplying the data signals to the data lines DL that are connected to the pixels  32 . The data electrode pads  49  may be formed having different angles according to a location of the data lines DL within the pixel area  31 . Specifically, the data electrode pads  49  and the data pad lines  48  may be formed at a relatively large angle in a case where the data lines DL are located at side parts of the display panel, and may be formed at a relatively small angle in a case where the data line DL are located at, or near a center portion of the display panel. Accordingly, the data pad part  44  may be connected with a data TCP  45  through the data electrode pads  49 . 
         [0039]    A plurality of data signal pads (not shown) may be formed along a direction corresponding to the data electrode pads  49  at one side of the data TCP  45  and electrically contact the data electrode pads  49 . That is, the data signal pads (not shown) may be formed at an angle equal to the angle of the data electrode pads  49  for preventing a short circuit between adjacent data electrode pads  49 . The plurality of data pad lines  48  connect the data electrode pads  49  to corresponding pixels  32  for supplying data signals through the data electrode pads  49  of the data pad part  44 . The data pad lines  48  may be formed parallel to the direction of the data electrode pads  49 . Thus, the pixels  32  receive the data signals from the data driving circuit  47 . 
         [0040]    It will be apparent to those skilled in the art that various modifications and variations can be made in the liquid crystal display device and a fabricating method thereof 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.