Abstract:
A tape carrier package (TCP) includes a film, a plurality of output leads and a plurality of input leads on the film, the plurality of output leads and the plurality of input leads being disposed on different sides, first and second TCP alignment marks arranged on opposing sides of the plurality of output leads, and a third TCP alignment mark at a central portion of the plurality of output leads.

Description:
[0001]    This application claims the benefit of the Korean Patent Application No. 2006-0050852 filed on Jun. 7, 2006, 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 (LCD) device, and more particularly to a driving circuit for driving the same. 
         [0004]      2 . Discussion of the Related Art 
         [0005]    A liquid crystal display (LCD) device includes an array substrate, a color filter substrate facing and spaced apart from the array substrate, and a liquid crystal layer disposed between the array substrate and the color filter substrate. The array substrate includes a gate line and a data line crossing each other. A thin film transistor (TFT) is connected to the gate line and the data line. The color filter substrate includes a color filter layer and a common electrode. 
         [0006]    The LCD device further includes a driving circuit. The driving circuit may be connected to the array substrate according to various attaching processes, such as a tape automated bonding (TAB) method and a chip on glass (COG) method. The structure of the LCD device according to the COG method is relatively simple since the driving circuit directly contacts the array substrate. However, as the size of the LCD device increases, it becomes more difficult to attach the driving circuit to the array substrate. In the TAB method, since the driving circuit is formed on a film of a tape carrier package (TCP), the bonding process is simple. However, an effective area of the array substrate is enlarged. Currently, the TAB method has been widely used as a bonding method of the driving circuit. 
         [0007]    In a TAB method, the driving circuit is formed as a driving integrated circuit (IC) and the TCP has input and output leads on the film. The driving IC is attached to inner portions of the input and output leads of the TCP film using a bump through an inner lead bonding (ILB) process. Outer portions of the output leads are attached to the array substrate using an anisotropic conductive film (ACF) through an output lead bonding (OLB) process. 
         [0008]      FIG. 1  is a perspective view showing an LCD device according to the related art.  FIG. 2  is a magnified view of portion “A” of  FIG. 1 . As shown in  FIGS. 1 and 2 , an LCD device includes a liquid crystal panel  10 . The liquid crystal panel  10  includes an array substrate  1  and a color filter substrate  3  facing and spaced apart from each other. A liquid crystal layer (not shown) is formed between the array substrate  1  and the color filter substrate  3 . A black matrix (not shown) and a color filter layer (not shown) are formed on the color filter substrate  3 . In addition, a gate line “GL” and a data line “DL” are formed on the array substrate  1 . The gate line GL crosses the data line DL to define a pixel region “P.” A thin film transistor (TFT) (not shown) is connected to the gate line GL and the data line DL at each pixel region P. 
         [0009]    The LCD device also includes a plurality of driving circuits  7  and  11 . Data pads (not shown) and gate pads (not shown) for connection with the driving circuits  7  and  11  are formed at a periphery of the array substrate  1 . Each gate pad is connected to a gate link line “GLK” extending from the gate line GL. Each data pad is connected to a data link line “DLK” extending from the data line DL. The driving circuit includes tape carrier packages (TCPs)  9  and printed circuit boards (PCBs)  5 . The TCPs  9  are connected to the corresponding gate and data pads. Each TCP  9  includes a film and one of a data driving circuit  7  and a gate driving circuit  11  as an integrated circuit (IC) on the film. The TCPs  9  are also connected to the printed circuit boards (PCBs)  5 . In addition, each TCP  9  includes a plurality of output leads  39   a  and a plurality of input leads  39   b  on the film. The plurality of output leads  39   a  correspond to one of the gate pads and the data pads on the array substrate  1 . Accordingly, the plurality of output leads  39   a  is disposed at an opposite side of the plurality of input leads  39   b . Even though not shown in  FIGS. 1 and 2 , the plurality of input leads  39   b  correspond to PCB pads on each PCB  5 . As a result, the PCBs  5  are electrically connected to the array substrate  1  through the TCPs  9  and supply signals to the liquid crystal panel  10 . 
         [0010]    The plurality of output leads  39   a  are equally spaced apart from one another. Further, the gate pads and the data pads corresponding to the plurality of output leads  39   a  are also equally spaced apart from one another so that the gate pads and the data pads correspond one-to-one with the plurality of output leads  39   a . Similarly, the plurality of input leads  39   b  are equally spaced apart from one another, and the PCB pads are equally spaced apart from one another so that the plurality of input leads  39   b  and the PCB pads are in one-to-one correspondence. 
         [0011]    The gate pads, the data pads, and the PCB pads may be divided into groups corresponding to one TCP  9 . Two alignment marks are formed at both sides of the plurality of output leads  39   a , and two marks are formed at both sides of each group of the gate pads and the data pads. The alignment marks are used to align the plurality of output leads  39   a  of each TCP  9  and one of the gate pads and the data pads of the liquid crystal panel  10 . Similarly, two alignment marks are formed at both sides of the plurality of input leads  39   b , and two alignment marks are formed at both sides of each group of the PCB pads to align the plurality of input leads  39   b  of each TCP  9  and the PCB pads of the PCB  5 . For example, two TCP alignment marks  41   a  and  41   b  are formed at both sides of the plurality of output leads  39   a  of each TCP  9 . Similarly, two panel alignment marks  42   a  and  42   b  are formed at both sides of each group of the gate pads and the data pads of the liquid crystal panel  10 . 
         [0012]      FIG. 3A  is a plan view showing a portion of a TCP of an LCD device according to the related art.  FIG. 3B  is a plan view showing a portion of a liquid crystal panel of the LCD device according to the related art. Even though  FIGS. 3A and 3B  show a plurality of output leads of the TCP and a plurality of gate pads of the liquid crystal panel, respectively,  FIGS. 3A and 3B  may also represent a plurality of input leads of the TCP and a plurality of data pads of the liquid crystal panel, respectively. As shown in  FIGS. 3A and 3B , a plurality of output leads  39   a  are formed in a first portion  45   a  of a TCP and a plurality of gate (or data) pads  43  are formed in a second portion  45   b  of a liquid crystal panel. The plurality of output leads  39   a  correspond one-to-one with the plurality of gate (or data) pads  43 . In addition, the plurality of output leads  39   a  are equally spaced apart from one another. Similarly, the plurality of gate (or data) pads  43  are equally spaced apart from one another. First and second TCP alignment marks  41   a  and  41   b  are formed at both sides of the plurality of output leads  39   a  while first and second panel alignment marks  42   a  and  42   b  are formed at both sides of the plurality of gate (or data) pads  43 . The first and second TCP alignment marks  41   a  and  41   b  correspond to the first and second panel alignment marks  42   a  and  42   b , respectively. 
         [0013]    The process for attaching the TCP to the liquid crystal panel will be illustrated hereinafter. The TCP and the liquid crystal panel are disposed using the first and second TCP alignment marks  41   a ,  41   b  and the first and second panel alignment marks  42   a ,  42   b  such that the plurality of output leads  39   a  overlap the plurality of gate (or data) pads  43 . An anisotropic conductive film (ACF), for example, is interposed between the plurality of output leads  39   a  and the plurality of gate (or data) pads  43 . Next, the TCP is pressed on the liquid crystal panel with heat. However, the first and second TCP alignment marks  41   a  and  41   b  may not be properly aligned with the first and second panel alignment marks  42   a  and  42   b  due to an accumulated alignment error during the fabrication process. Moreover, since the TCP expands by the pressure and the heat during the attaching process, the mismatch between the TCP alignment marks  41   a ,  41   b  and the panel alignment marks  42   a ,  42   b  may become worse. As a result, when the TCP and the liquid crystal panel are aligned using the first and second TCP alignment marks  41   a ,  41   b  and the first and second panel alignment marks  42   a ,  42   b , the plurality of output leads  39   a  and the plurality of gate (or data) pads  43  may be misaligned. Similarly, the plurality of input leads  39   b  (of  FIG. 2 ) and the plurality of PCB pads may be misaligned. 
         [0014]    According to recent trends in reducing the cost of materials, the width of TCPs have decreased from about 48 mm to about 35 mm. Accordingly, a gap distance between two adjacent output leads  39   a  and between two adjacent gate (or data) pads  43  also decreased. As the gap distance decreases, misalignment during the attachment of the TCP and the liquid crystal panel increases. The misalignment causes deterioration in display quality of the LCD device. In addition, since the misaligned TCP and the liquid crystal panel need to be re-attached, fabrication yield is reduced and production cost increases. 
       SUMMARY OF THE INVENTION 
       [0015]    Accordingly, the present invention is directed to a driving circuit and liquid crystal display device including the same that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
         [0016]    An object of the present invention is to provide a liquid crystal display device with improved alignment between tape carrier packages and the liquid crystal panel. 
         [0017]    Another object of the present invention is to provide a liquid crystal display device with improved picture quality, increased fabrication yield, and reduced production cost. 
         [0018]    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. 
         [0019]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a tape carrier package (TCP) includes a film, a plurality of output leads and a plurality of input leads on the film, the plurality of output leads and the plurality of input leads being disposed on different sides, first and second TCP alignment marks arranged on opposing sides of the plurality of output leads, and a third TCP alignment mark at a central portion of the plurality of output leads. 
         [0020]    In another aspect, a liquid crystal display (LCD) device includes at least one tape carrier package (TCP), the TCP including a film, a plurality of output leads and a plurality of input leads on the film, the plurality of output leads disposed at different sides of the plurality of input leads, first and second TCP alignment marks at both sides of the plurality of output leads, and a third TCP alignment mark at a central portion of the plurality of output leads, and a liquid crystal panel including a plurality of gate pads and a plurality of data pads, the plurality of output leads of the TCP contacting corresponding ones of the plurality of gate pads and the plurality of data pads, first and second panel alignment marks corresponding to the first and second TCP alignment marks, and a third panel alignment mark corresponding to the third TCP alignment mark, and a printed circuit board (PCB) including a plurality of PCB pads contacting the plurality of input leads, wherein the liquid crystal panel and the printed circuit board are connected to each other through the at least one TCP. 
         [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  is a perspective view showing a liquid crystal display device according to the related art; 
           [0024]      FIG. 2  is a magnified view of portion “A” of  FIG. 1 ; 
           [0025]      FIG. 3A  is a plan view showing a portion of a TCP of a liquid crystal display device according to the related art; 
           [0026]      FIG. 3B  is a plan view showing a portion of a liquid crystal panel of a liquid crystal display device according to the related art; 
           [0027]      FIG. 4  is a schematic cross-sectional view showing a liquid crystal panel for a liquid crystal display device according to an embodiment of the present invention; 
           [0028]      FIG. 5  is a perspective view showing a liquid crystal display device according to an embodiment of the present invention; 
           [0029]      FIG. 6  is a magnified view of portion “B” of  FIG. 5 ; 
           [0030]      FIG. 7A  is a plan view showing a tape carrier package (TCP) of a liquid crystal display device according to an embodiment of the present invention; and 
           [0031]      FIG. 7B  is a plan view showing a liquid crystal panel for a liquid crystal display device according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
         [0033]      FIG. 4  is a schematic cross-sectional view showing a liquid crystal panel for a liquid crystal display (LCD) device according to an embodiment of the present invention. 
         [0034]    As shown in  FIG. 4 , a liquid crystal panel  110  includes a first substrate  101 , a second substrate  103  facing the first substrate  101 , and a liquid crystal layer  220  between the first and second substrates  101  and  103 . The liquid crystal panel  110  includes a display area “AA” for displaying images and a non-display area “NA” at a periphery of the display area AA. A plurality of gate pads  125  and a plurality of data pads (not shown) are formed in a gate pad portion “GPA” and a data pad portion (not shown), respectively, in the non-display area NA on the first substrate  101 . In addition, a gate line “GL” and a gate electrode  105  are formed on the first substrate  101 , and a gate insulating layer  113  is formed on the gate line GL and the gate electrode  105 . An active layer  107  is formed on the gate insulating layer  113  over the gate electrode  105 , and an ohmic contact layer  109  is formed on the active layer  107 . Source and drain electrodes  111   a  and  111   b  spaced apart from each other are formed on the ohmic contact layer  109 . A data line “DL” is formed on the gate insulating layer  113 . Even though not shown in  FIG. 4 , the data line DL crosses the gate line GL to define a pixel region “P” in the display area AA. The gate electrode  105 , the active layer  107 , the source electrode  111   a , and the drain electrode  111   b  constitute a thin film transistor (TFT) “T.” A passivation layer  115  is formed on the source and drain electrodes  111   a  and  111   b , and a pixel electrode  117  contacting the drain electrode  111   b  is formed on the passivation layer  115 . The gate pad  125  and the data pad (not shown) in the non-display area NA are connected to the gate line GL and the data line DL, respectively. 
         [0035]    A black matrix  129  is formed on the second substrate  103 , and a color filter layer  123  including red (R), green (G), and blue (B) color filters is formed on the black matrix  29  and the second substrate  103 . A planarization layer  121  is formed on the color filter layer  123  and the black matrix  129  to reduce a step difference. A common electrode  119  is formed on the planarization layer  121 . A seal pattern  127  is formed in the non-display area NA between the first and second substrates  101  and  103 . The seal pattern  127  maintains a cell gap between the first and second substrates  101  and  103  and prevents leakage of liquid crystal materials. In addition, the first and second substrates  101  and  103  are attached to each other by the seal pattern  127 . 
         [0036]      FIG. 5  is a perspective view showing an LCD device according to an embodiment of the present invention.  FIG. 6  is a magnified view of portion “B” of  FIG. 5 . 
         [0037]    As shown in  FIGS. 5 and 6 , a liquid crystal panel  110  is connected to a driving circuit ( 135 ,  137 ) using a tape automated bonding (TAB) method. A plurality of gate pads (not shown) and a plurality of data pads (not shown) are formed in a non-display area NA on the first substrate  101 . Each of the plurality of gate pads is connected to a gate link line “GLK” extending from a gate line GL. Each of the plurality of data pads is connected to a data link line “DLK” extending from a data line DL. A plurality of tape carrier packages (TCPs)  133  are connected to a periphery of the liquid crystal panel  110 . Each TCP  133  includes a film and one of a gate driving circuit  135  and a data driving circuit  137  as an integrated circuit (IC) on the film. Each TCP  133  further includes a plurality of output leads  139   a  and a plurality of input leads  139   b  on the film. The plurality of output leads  139   a  is disposed at an opposite side of the plurality of input leads  139   b . In addition, a plurality of printed circuit boards (PCBs)  131  is connected to the plurality of TCPs  133 . Even though not shown in  FIGS. 5 and 6 , each PCB  131  includes a plurality of PCB pads. Each output lead  139   a  contacts one of a corresponding gate pad and data pad, and each input lead  139   b  contacts one of the plurality of PCB pads. Accordingly, the plurality of PCBs  131  is electrically connected to the liquid crystal panel  110  through the TCPs  133  and supply signals to the liquid crystal panel  110 . 
         [0038]    The plurality of output leads  139   a  are equally spaced apart from one another. Further, the plurality of gate pads and the plurality of data pads corresponding to the plurality of output leads  139   a  are also equally spaced apart from one another so that the plurality of gate pads and the plurality of data pads correspond one-to-one with the plurality of output leads  139   a . Similarly, the plurality of input leads  139   b  are equally spaced apart from one another, and the plurality of PCB pads are equally spaced apart from one another so that the plurality of input leads  139   b  and the plurality of PCB pads are in one-to-one correspondence. The plurality of gate pads, the plurality of data pads, and the plurality of PCB pads may be divided into groups corresponding to a single TCP  133 . 
         [0039]    Three alignment marks ( 141   a - 141   c ) are formed at both sides of the plurality of output leads  139   a  and at a central portion of the plurality of output pads  139   a . In addition, three alignment marks ( 142   a - 142   c ) are formed at both sides of each group of the plurality of gate (or data) pads and at a central portion. Accordingly, the plurality of output leads  139   a  of each TCP  133  are aligned with each group of the plurality of gate pads and the plurality of data pads of the liquid crystal panel  110  using the three alignment marks of each TCP  133  and the three alignment marks of the liquid crystal panel  110 . 
         [0040]    Similarly, three alignment marks (not shown) are formed at both sides of the plurality of input leads  139   b  and at a central portion of the plurality of input leads  139   b . In addition, three alignment marks (not shown) are formed at both sides of each group of the PCB pads and at a central portion. Accordingly, the plurality of input leads  139   b  of each TCP  133  are aligned with each group of the plurality of PCB pads of the PCB  131  using the three alignment marks of each TCP  133  and the three alignment marks of the PCB  131 . For example, first and second TCP alignment marks  141   a  and  141   b  may be formed at both sides of the plurality of output leads  139   a  and a third TCP alignment mark may be formed at a central portion of the plurality of output leads  139   a . Moreover, first and second panel alignment marks  142   a  and  142   b  may be formed at both sides of the gate (or data) pads, and a third panel alignment mark  142   c  may be formed at a central portion of the gate (or data) pads. 
         [0041]      FIG. 7A  is a plan view showing a portion of a TCP of an LCD device according to an embodiment of the present invention.  FIG. 7B  is a plan view showing a portion of a liquid crystal panel of an LCD device according to an embodiment of the present invention. Even though  FIGS. 7A and 7B  show a plurality of output leads of the TCP and a plurality of gate pads of the liquid crystal panel, respectively,  FIGS. 7A and 7B  may also represent a plurality of input leads of the TCP and a plurality of PCB pads of the PCB, respectively. 
         [0042]    As shown in  FIGS. 7A and 7B , a plurality of output leads  139   a  are formed in a first portion  145   a  of a TCP and a plurality of gate (or data) pads  143  are formed in a second portion  145   b  of a liquid crystal panel. The plurality of output leads  139   a  correspond one-to-one with the plurality of gate (or data) pads  143 . In addition, the plurality of output leads  139   a  are substantially equally spaced apart from one another, and the plurality of gate (or data) pads  143  are substantially equally spaced apart from one another. Further, first and second TCP alignment marks  141   a  and  141   b  are formed at both sides of the plurality of output leads  139   a  and a third TCP alignment mark  141   c  is formed at a central portion of the plurality of output leads  139   a . Moreover, first and second panel alignment marks  142   a  and  142   b  are formed at both sides of the plurality of gate (or data) pads  143  and a third panel alignment mark  142   c  is formed at a central portion of the plurality of gate (or data) pads  143 . The first, second, and third TCP alignment marks  141   a ,  141   b , and  141   c  correspond to the first, second, and third panel alignment marks  142   a ,  142   b , and  142   c , respectively. 
         [0043]    The plurality of output leads  139   a  may be classified into a first group  147   a  of output leads and a second group  147   b  of output leads. The first group  147   a  of output leads is disposed at the central portion of the plurality of output leads  139   a  and corresponds to the third TCP alignment mark  141   c . The second group  147   b  of output leads is disposed at both sides of the first group  147   a  of output leads. 
         [0044]    Similarly, the plurality of gate (or data) pads  143  may be classified into a third group  149   a  of gate (or data) pads and a fourth group  149   b  of gate (or data) pads. The third group  149   a  of gate (or data) pads is disposed at the central portion of the plurality of gate (or data) pads  143  and corresponds to the third panel alignment mark  142   c . The fourth group  149   b  of gate (or data) pads is disposed at both sides of the third group  149   a  of gate (or data) pads. 
         [0045]    The output leads of the first group  147   a  contact the gate (or data) pads of the third group  149   a . The output leads of the first group  147   a  are shorter than the output leads of the second group  147   b . Similarly, the gate (or data) pads of the third group  149   a  are shorter than the gate (or data) pads of the fourth group  149   b . Since areas corresponding to the third TCP alignment mark  141   c  and the third panel alignment mark  142   c  are utilized for attaching the TCP to the liquid crystal panel, reliability of connection is improved. Moreover, an increase in margins for a pad width and a pad pitch are obtained even when a width of the TCP decreases. 
         [0046]    Further, the output leads of the first group  147   a  may have a narrower width than the output leads of the second group  147   b . As a result, even when a number of the output leads increases due to increase of a resolution of the liquid crystal panel and/or a width of the TCP decreases for reducing a material cost, a reliable connection between the TCP and the liquid crystal panel is achieved by the TAB method. In an alternative embodiment, the width of the plurality of output leads  139   a  may gradually decrease towards the central portion of the plurality of output leads  139   a.    
         [0047]    Process for attaching the TCP to the liquid crystal panel includes the steps of aligning the TCP and the liquid crystal panel using the first, second, and third TCP alignment marks  141   a ,  141   b , and  141   c  and the first, second, and third panel alignment marks  142   a ,  142   b , and  142   c . As a result, the TCP is positioned over the liquid crystal panel such that the plurality of output leads  139   a  overlap the plurality of gate (or data) pads  143 . An anisotropic conductive film (ACF) is interposed between the plurality of output leads  139   a  and the plurality of gate pads  143 . Next, the TCP is pressed on the liquid crystal panel with heat. 
         [0048]    According to the present invention, after the TCP and the liquid crystal panel are aligned using the third TCP alignment mark  141   c  and the third panel alignment mark  142   c , pressure and heat may be applied to the TCP and the liquid crystal panel from the central portion of the plurality of output leads  139   a  outwards to the outer sides of the plurality of output leads  139   a . Since additional third alignment marks  141   c  and  142   c  are used, the TCP is aligned more accurately with the liquid crystal panel and the PCB even when the TCP expands by accumulated errors, pressure, and heat. In addition, even though the output leads of the first group  147   a  have a narrower width than the output leads of the second group  147   b , the output leads of the first group  147   a  contact the gate (or data) pads of the third group  149   a  more accurately due to the third TCP alignment mark  141   c  and the third panel alignment mark  142   c . The plurality of output leads  139   a  may be re-aligned with the plurality of gate (or data) pads  143  during the attachment process. As a result, reliability of the attachment process is improved. Moreover, since the output leads of the second group  147   b  have a wider width than the output leads of the first group  147   a , the output leads of the second group  147   b  contact the gate (or data) pads of the fourth group  149   b  more accurately even when the TCP expands by accumulated errors, pressure, and heat. 
         [0049]    Consequently, in the LCD device according to the present invention, the TCP is attached to the PCB and the liquid crystal panel using a TAB method in accordance with first and second alignment marks at both sides of a plurality of pads and a third alignment mark at a central portion of the plurality of pads. Accordingly, the plurality of output leads of the TCP contact the plurality of gate pads and the plurality of data pads of the liquid crystal panel without misalignment, and the plurality of input leads of the TCP contact the plurality of PCB pads of the PCB without misalignment. Therefore, deterioration in display quality due to the misalignment is prevented. Further, reduction in production yield and increase in fabrication cost for re-attaching the TCP due to misalignment are prevented. 
         [0050]    It will be apparent to those skilled in the art that various modifications and variations can be made in the liquid crystal display device 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.