Abstract:
An apparatus for fabricating a liquid crystal display device includes a controller for providing nitrogen (N 2 ) gas at a constant pressure, a plurality of dispensers receiving the nitrogen gas from the controller, each of the dispensers dotting a silver paste at two or more regions of a first substrate, and a plurality of flow control valves each introducing the nitrogen gas into each of the plurality of dispensers at the same pressure.

Description:
[0001]     The present invention claims the benefit of Korean Patent Application No. 63090/2003, filed in Korea on Sep. 9, 2003, 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 an apparatus for fabricating a liquid crystal display device and a method of fabricating a liquid crystal display device.  
         [0004]     2. Description of the Related Art  
         [0005]     In general, a process of fabricating a liquid crystal display (LCD) device includes a substrate fabrication process, a cell fabrication process, and a module process. During the substrate fabrication process, a plurality of thin film transistors (TFTs) are fabricated onto a cleaned glass substrate during TFT fabrication processes, and a color filter is fabricated onto a cleaned glass substrate during color filter fabrication processes. During the TFT fabrication processes, the plurality of TFTs and a plurality of pixel electrodes are fabricated on a first substrate. During the color filter fabrication processes, red, green, and blue color filter layers are formed using a dye or pigment, and a common electrode (ITO) is formed on a second substrate upon which a black matrix is formed.  
         [0006]     During the cell fabrication process, liquid crystal material is injected between a first substrate and a second substrate, thereby forming an LCD cell panel. Accordingly, the first substrate is provided with the TFTs and the pixel electrodes, and the second substrate is provided with the color filters and the common electrode. Thus, the first substrate and the second substrate are attached to each other with a space therebetween, and the liquid crystal material in injected into the space.  
         [0007]     During the module process, a circuit section for processing signals is fabricated, and a module is fabricated by connecting the LCD cell panel with the signal processing circuit section.  
         [0008]     The cell fabrication process requires processes for performing grounding to generate a voltage difference between the two substrates according to the electric signals, as well as processes for attaching the first substrate and the second substrate together. These processes are achieved by connecting the common electrode of the second substrate to the first substrate.  
         [0009]     The method of manufacturing an LCD according to related art will now be described.  
         [0010]      FIG. 1  is a plan view of an LCD panel according to the related art, and  FIG. 2  is a cross sectional view along I-I of  FIG. 1  according to the related art. In  FIG. 1 , an LCD device includes a first substrate  1 , a second substrate  2 , an active region  12 , a sealant  7 , and silver pastes  8 . The active region  12  includes a plurality of pixel regions  6 , which are defined by a plurality of gate lines  3  and a plurality of data lines  5  arranged in a matrix configuration on the first substrate  1 . In order to protect the liquid crystal material (not shown) within the active region  12  from damage, the sealant  7  surrounds edges of the active region  12 , thereby attaching the first substrate  1  to the second substrate  2 . In addition, the silver (Ag) pastes  8  are formed outside the sealant  7 . The silver pastes  8  are spaced from each other, and electrically ground the first substrate  1  and the second substrate  2  using silver particles in the silver pastes  8  as a conductive material. The silver pastes  8  include two or more silver pastes formed on the first and second substrates  1  and  2 . For example, when the first and second substrates  1  and  2  are small-sized, two silver pastes  8  may be formed at top and bottom corners of the first and second substrates  1  and  2 .  
         [0011]     In  FIG. 2 , the LCD device includes a first substrate  1 , gate lines (not shown), a gate insulating film  9 , a semiconductor layer  10 , thin film transistors (not shown), a passivation film  15 , pixel electrodes  16 , and a first alignment film  17   a . Each of the gate lines (not shown) include a gate electrode  4  extending therefrom, and are formed along an inner surface of the first substrate  1 . In addition, the gate lines (not shown) are arranged in rows along the inner surface of the first substrate  1 , and the gate insulating film  9  is formed along an entire surface of the first substrate  1 . The semiconductor layer  10  is formed having an island shape on the gate insulating film  9  at an upper side of the gate electrode  4 .  
         [0012]     Then, a source electrode  13   a  and a drain electrode  13   b  are formed on the semiconductor layer  10 , thereby completing the thin film transistor (not shown). Next, the passivation film  15  is formed along the entire surface of the first substrate  1  including the source electrode  13   a  and the drain electrode  13   b . Then, the pixel electrodes  16  are formed on the passivation film  15 , and are connected to the drain electrodes  13   b . Accordingly, the first alignment film  17   a  aligns liquid crystal molecules of a liquid crystal material (not shown) disposed between the first and second substrates  1  and  2 .  
         [0013]     In  FIG. 2 , the second substrate  2  includes a black matrix  18 , a color filter layer  19 , a common electrode  21 , and a second alignment film  17   b . The black matrix  18  is formed along an inner surface of the second substrate  2 , and blocks light corresponding to the gate lines  3 , the data lines  5 , and the thin film transistor (not shown). The color filter layer  19  produces colored light at portions corresponding to the pixel electrodes  16 . Then, the common electrode  21  is formed on the black matrix  18  and the color filter layer  19 , and generates a voltage difference between the common electrode  21  and the pixel electrode  16  of the first substrate  1 . Next, the second alignment film  17   b  is formed on the common electrode  21  and aligns the liquid crystal molecules of the liquid crystal material (not shown) disposed between the first and second substrates  1  and  2 .  
         [0014]     The LCD device further includes the liquid crystal material (not shown), spacers  22 , a sealant  7 , and silver pastes  8 . The liquid crystal molecules are aligned by the first and second alignment films  17   a  and  17   b  between the first substrate  1  and the second substrate  2 , and the spacers  22  are made of plastic material and maintain the space between the first substrate  1  and the second substrate  2 . In order to prevent moisture and foreign material from being introduced into the liquid crystal material, the sealant  7  is attached to the edges of the active region  12 , as shown in  FIG. 1 , of the first and second substrates  1  and  2 , thereby sealing the active region  12 . The silver pastes  8  electrically connect the common electrode to the first substrate at an exterior portion of the sealant  7 .  
         [0015]     A method of fabricating the above-described LCD panel includes performing a TFT array process on the first substrate  1  and performing a pixel electrode process on the second substrates  2 . Then, the spacers  22  are dispersed onto one of the first or second substrates  1  or  2  to maintain a uniform interval between the first substrate  1  and the second substrate  2 . Next, the sealant  7 , such as thermosetting resin or epoxy resin hardened by ultraviolet, is printed at edges of the active region  12  of the first and second substrates  1  and  2 . Then, the silver pastes  8  are formed to connect the common electrode of the second substrate  2 , wherein the silver pastes  8  can be formed using a print method including a screen mask or using a dotting method including a dispenser.  
         [0016]     During the print method, the screen mask is placed on the second substrate  2  and the silver pastes are printed onto the second substrate  2  including the screen mask. This method is disadvantageous since significant amounts of the silver pastes is wasted.  
         [0017]     During the dotting method, the silver pastes are individually formed one-by-one so that the silver pastes  8  may be formed at desired positions using proper amounts of silver.  
         [0018]      FIG. 3  is a plan view of a dotting method for fabricating an LCD device according to the related art. In  FIG. 3 , an LCD device includes a first substrate  1 , a plurality of LCD cells  25  formed on the first substrate  1 , a sealant  7  surrounding edges of an active region  12  within the LCD cell  25 , and silver pastes  8  dotted at an exterior portion of the sealant  7 .  
         [0019]     A dispenser  24  is used to dot the silver pastes  8  at the desired positions of the first substrate  1  using an extrusion process that includes application of a predetermined pneumatic pressure from a controller (not shown).  
         [0020]     During the cell fabrication process, the silver pastes  8  should be formed with a predetermined size and at predetermined interval distances between each of the silver pastes  8  around the sealant  7  of the LCD cell of the second substrate  2  to enhance productivity. However, during the process of dotting the silver pastes, since the controllers for providing pneumatic pressure correspond to the dispensers  24  in a one-to-one relationship, the dispenser  24  should move many times so as to dot the plurality of silver pastes  8  for each of the individual LCD cells. In other words, significant amounts of tacking time is required to manufacture the LCD device.  
       SUMMARY OF THE INVENTION  
       [0021]     Accordingly, the present invention is directed to an apparatus and a method of fabricating an LCD device that substantially obviate one or more problems due to limitations and disadvantages of the related art.  
         [0022]     An object of the present invention is to provide an apparatus for supplying dispensers to reduce tacking time.  
         [0023]     Another object of the present invention is to provide a method for supplying dispensers to reduce tacking time.  
         [0024]     Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned from 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.  
         [0025]     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, an apparatus for fabricating a liquid crystal display device includes a controller for providing nitrogen (N 2 ) gas at a constant pressure, a plurality of dispensers receiving the nitrogen gas from the controller, each of the dispensers dotting a silver paste at two or more regions of a first substrate, and a plurality of flow control valves each introducing the nitrogen gas into each of the plurality of dispensers at the same pressure.  
         [0026]     In another aspect, a method of fabricating a liquid crystal display device includes preparing a first substrate and a second substrate, the first substrate having a plurality of liquid crystal display cells each comprising a thin film transistor and a pixel electrode, and the second substrate having a color filter layer and a common electrode, coating a plurality of sealants onto the first substrate, each sealant surrounding edges of an active region of each of the plurality of liquid crystal display cells, dispersing a plurality of spacers onto the first substrate, simultaneously dispensing a plurality of silver pastes spaced apart by a predetermined interval distance from each other at an exterior portion of the sealants coated onto the plurality of liquid crystal display cells, and attaching the first substrate to the second substrate.  
         [0027]     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]     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 principle of the invention. In the drawings:  
         [0029]      FIG. 1  is a plan view of an LCD panel according to the related art;  
         [0030]      FIG. 2  is a cross sectional view along I-I′ of  FIG. 1  according to the related art;  
         [0031]      FIG. 3  is a plan view of a dotting method for fabricating an LCD device according to the related art;  
         [0032]      FIG. 4  is a plan view of an exemplary apparatus for fabricating an LCD device according to the present invention;  
         [0033]      FIG. 5  is a cross sectional view of an exemplary LCD device according to the present invention; and  
         [0034]      FIG. 6  is a flowchart representing an exemplary method of fabricating an LCD device according the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0036]      FIG. 4  is a plan view of an exemplary apparatus for fabricating an LCD device according to the present invention. In  FIG. 4 , an LCD device may include a first substrate  31 , a plurality of LCD cells  35  formed on the first substrate  31 , a sealant  37  surrounding the edges of an active region  42  within the LCD cell  35 , and silver pastes  38  dotted on a plurality regions at an exterior portion of the sealant  37 . The plurality of LCD cells  35  may include TFTs and pixel electrodes, and the active region  42  may correspond to a region upon which the TFT and pixel electrode are formed for displaying images. Accordingly, the silver pastes  38  may be formed to electrically ground a common electrode (not shown) formed on a second substrate (not shown) that may oppose the first substrate  1 .  
         [0037]     In  FIG. 4 , an apparatus for manufacturing the LCD may include a controller  60 , a plurality of dispensers  62 , and a flow control valve  64 . The controller  60  may constantly supply the dispensers  62  with a predetermined pressure of nitrogen gas. Accordingly, the plurality of dispensers  62  may provide dots of silver paste on a plurality of regions of the first substrate  1 . The flow control valve  64  may control the flow rate of the nitrogen gas to introduce the nitrogen gas into the plurality of dispensers  62  at the same pressure. For example, the predetermined pressure may be pneumatic pressure within a range of about 0.1 MPa to about 1 MPa. Accordingly, the controller  60  may supply the nitrogen gas to a plurality of the dispensers  62 , the plurality of dispensers  62  may simultaneously dot a plurality of the silver pastes on a plurality of the LCD cells. As a result, tracking time of the dispensers  62  may be reduced.  
         [0038]     In addition, according to the present invention, the plurality of dispensers  62  connected to the same controller  60  for supplying the dispensers  62  with nitrogen gas may be positioned at a plurality of regions where the silver pastes should be dotted, and may be spaced from each other with a predetermined distance. Then, the plurality of dispensers  62  may simultaneously dot the silver pastes by extrusion due to pressure of nitrogen gas, thereby reducing the time to complete the dotting process.  
         [0039]     In  FIG. 4 , each of the dispensers  62  may be provided with a flow control valve  64  to constantly control the flow rate of the nitrogen gas introduced into each of the dispensers  62 . As a result, equal amounts of the silver pastes may be dotted.  
         [0040]      FIG. 5  is a cross sectional view of an exemplary LCD device according to the present invention, and  FIG. 6  is a flowchart representing an exemplary method of fabricating an LCD device according the present invention. In  FIGS. 5 and 6 , a method of fabricating an LCD device may include preparing a first substrate  31  and a second substrate  32  (ST 61 ), wherein the first substrate  31  may be provided with a plurality of LCD cells each including a thin film transistors and a pixel electrode and the second substrate  32  may be positioned to face the first substrate  31 , and may include a color filter layer and a common electrode.  
         [0041]     In  FIG. 5 , the plurality of LCD cells may be formed on the first substrate  31 , and  1  plurality of gate lines (not shown) each including a gate electrode  34  may be formed on the LCD cell. Then, a gate insulating film  39  may be formed to insulate the gate line and the gate electrode  34 , and a semiconductor layer  40  may be formed on the gate insulating film  39  corresponding to the gate electrode  34 . Next, a source electrode  43   a  and a drain electrode  43   b  may be formed at both sides of the semiconductor layer  40  to form a thin film transistor structure.  
         [0042]     Then, in order to insulate and planarize a data line (not shown), which may be concurrently formed with the source electrode  43   a  and the drain electrode  43   b , a passivation film  45  may be formed along an entire surface of a resultant structure of the first substrate  31 . Then, a pixel electrode (ITO)  46  may be formed on the passivation film  45 , and may be connected to the drain electrode  43   b . Next, a first alignment film  47   a  may be formed on the pixel electrode  64 .  
         [0043]     In  FIG. 5 , a black matrix  48  for blocking a light from being leaked may be formed at portions corresponding to the gate line, the data line, and the thin film transistor on the second substrate  32 . Then, a color filter layer  49  including red, green, and blue unit cells may be formed on a portion corresponding to the pixel electrode  46  between the black matrixes  48 . Next, an Indium Tin Oxide (ITO) electrode may be formed as a common electrode  51  on the color filter layer  49  and the black matrix  48  to induce a voltage difference between the common electrode  51  and the pixel electrode  46  driven by the thin film transistor of the first substrate  31 . Then, a second alignment film  47   b  may be formed on an outer surface of the second substrate to provide an orientation of liquid crystal  53 .  
         [0044]     After the first and second substrates  31  and  32  are prepared, a sealant  37  may be coated on the first substrate  31  so as to surround edges of an active region of each of the plurality of LCD cells  35  (ST 62 ). Then, spacers  52  may be dispersed onto the first substrate  31  to maintain a uniform cell gap between the first substrate  31  and the second substrate  32  (ST 63 ). In addition, the coating the sealant  37  and the dispersing the spacers  52  may be simultaneously performed.  
         [0045]     Then, silver pastes  38  may be simultaneously formed that are spaced by a predetermined interval distance from each other at an exterior portion of the sealant  37  coated on the plurality of LCD cells (ST 64 ).  
         [0046]     As shown in  FIG. 4 , the silver pastes  38  may be simultaneously formed using a flow control valve  64  and a plurality of dispensers  62  connected to one controller  60 . In other words, the dispensers  62  may be positioned and spaced from each other with a predetermined distance on a plurality of regions where the silver pastes  38  should be dotted, and simultaneously dot equal, amounts of silver pastes  38 . Consequently, the silver pastes  38  may be dotted by the apparatus for fabricating an LCD device according to the present invention.  
         [0047]     In  FIGS. 5 and 6 , after the sealant  37 , the spacers  52 , and silver pastes  38  are formed on the first substrate  31 , the first substrate  31  may be attached to the second substrate  32  (ST 65 ). Accordigly, before the first substrate  31  is attached to the second substrate  32 , liquid crystal material (not shown) may be drop-filled onto the first substrate  31 . Alternatively, after the first substrate  31  is attached to the second substrate  32 , the liquid crystal material may be injected into the cell gap formed between the first substrate  31  and the second substrate  32 .  
         [0048]     According to the present invention, tracking time required to fabricate the LCD device may reduced and the silver dots may be of equal amounts.  
         [0049]     It will be apparent to those skilled in the art that various modifications and variations can be made in the apparatus and method for fabricating a 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.