Abstract:
A liquid crystal display (LCD) device includes: a first substrate opposite a second substrate and coupled to the second substrate by a first seal pattern; a liquid crystal layer interposed between the first and second substrates within the first seal pattern; a second seal pattern sealing an injection hole in the first seal pattern; and a common line disposed at a first surface of the first substrate and having a predetermined pattern that exposes the second seal pattern to a second surface of the first substrate.

Description:
This application claims the benefit of Korean Patent Application No. 10-2006-0121605, filed on Dec. 4, 2006 in Korea, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display (LCD) device and a method of fabricating the same. 
     2. Discussion of the Related Art 
     Until recently, display devices have typically used cathode-ray tubes (CRTs). Presently, many efforts and studies are being made to develop various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays, and electro-luminescence displays (ELDs), as a substitute for CRTs. Of these flat panel displays, LCD devices have many advantages, such as high resolution, light weight, thin profile, compact size, and low voltage power supply requirements. 
     In general, an LCD device includes two substrates that are spaced apart and face each other with a liquid crystal material interposed between the two substrates. The two substrates include electrodes that face each other such that a voltage applied between the electrodes induces an electric field across the liquid crystal material. Alignment of the liquid crystal molecules in the liquid crystal material changes in accordance with the intensity of the induced electric field into the direction of the induced electric field, thereby changing the light transmittance of the LCD device. Thus, the LCD device displays images by varying the intensity of the induced electric field. 
       FIG. 1  is a schematic perspective view illustrating an LCD device according to the related art. 
     In  FIG. 1 , the LCD device  51  includes an upper substrate  5 , a lower substrate  10  facing and spaced apart from the upper substrate  5 , and a liquid crystal layer “LC” between the upper and lower substrates  5  and  10 . 
     A gate line  14  and a data line  26  cross each other to define a pixel region “P” on an inner surface of the lower substrate  10 , a thin film transistor “T” is formed at crossing the gate line  14  and the data line  26 , and a pixel electrode  32  is connected to the thin film transistor “T” in the pixel region “P.” 
     Further, a black matrix  6  is formed on an inner surface of the upper substrate  5 , a color filter layer  7  is formed on the black matrix  6 , and a common electrode  9  is formed on the color filter layer  7 . Here, the color filter layer  7  includes red, green and blue sub-color filters  7   a ,  7   b  and  7   c . Each of the red, green and blue sub-color filters  7   a ,  7   b  and  7   c  is disposed in the pixel region “P,” and the black matrix  6  is disposed in a non-pixel region (not shown) in a periphery of the pixel region “P.” 
     The first and second substrates  5  and  10  are attached with a seal pattern (not shown). The LCD device  51  operates with signals from an external printed circuit board (not shown). The gate line  14  is supplied with a gate signal, the data line  26  is supplied with a data signal, and the common electrode  9  is supplied with a common signal. 
     The gate signal switches the thin film transistor “T” and the data signal is applied to the pixel electrode  32 . By applying the pixel and common electrodes  32  and  9  to the corresponding signals, an electric field is induced. Liquid crystal molecules of the liquid crystal layer “LC” are arranged by the induced electric field, and the light transmittance of the LCD device  51  is changed, thus images are displayed. 
     A gate pad and a data pad (not shown) are formed at one ends of the gate line  14  and the data line  26  to be supplied with the gate signal and the data signal, respectively. 
       FIG. 2  is a schematic plan view illustrating an array substrate for an LCD device according to the related art. 
     In  FIG. 2 , the gate line  14  and the data line  26  crosses each other to define the pixel region “P” on the upper substrate  10 . A gate pad “GP” is at one end of the gate line  14 , and a data pad “DP” is at one end of the data line  26 . A gate pad electrode “GPE” contacts and is on the gate pad “GP,” and a data pad electrode “DPE” contacts and is on the data pad “DP”. A thin film transistor “T” is located at a crossing of the gate and data lines  14  and  26 . The thin film transistor “T” includes a gate electrode  12 , a semiconductor layer  16  and source and drain electrodes  18  and  20 . A pixel electrode  32  is disposed in the pixel region “P” and connected to the drain electrode  20 . 
     A first capacitor electrode  15  extends from the gate line  14 , and a second capacitor electrode  24  overlaps with the first capacitor electrode  15  and is connected to the pixel electrode  32  via a contact hole  25 . The first and second capacitor electrodes  15  and  24  and an insulating layer (not shown) therebetween constitute a storage capacitor “Cst.” 
     The gate and data pads “GP and DP” are disposed in a non-display region (not shown). Other signals lines are also formed in the non-display region, for example, a common line (not shown) is formed in the non-display region. When a small-sized LCD device is fabricated, the first and second substrates  5  and  10  (of  FIG. 1 ) are attached with a conductive seal pattern (not shown). The common line (not shown) contacts the conductive seal pattern to supply a common signal to the common electrode  9  ( FIG. 1 ). 
       FIG. 3  is a schematic plan view illustrating an LCD device according to the related art. 
     In  FIG. 3 , the LCD device  50  includes first and second substrates  52  and  54  attached with a conductive seal pattern  56 . The LCD device  50  has a display region “DA” and a non-display region “NDA” in a periphery of the display region “DA.” 
     When the first substrate  52  is an array substrate and the second substrate  54  is a color filter substrate, the first substrate  52  protrudes beyond the second substrate  54 . 
     The conductive seal pattern  56  attaches the first and second substrates  52  and  54  and maintains a cell gap between the first and second substrates  52  and  54 . Further, the conductive seal pattern  56  has an injection hole  58  for injecting a liquid crystal layer “LC” between the first and second substrates  52  and  54 , and an adhesive pattern  60  seals the injection hole  58  after injecting the liquid crystal layer “LC.” Further, a common line  62  is formed at a boundary between the display region “DA” and the non-display region “NDA” to contact the conductive seal pattern  56 . Therefore, a portion of the common line  62  overlaps with the adhesive pattern  60  at the injection hole  58  in a plan view. Here, the common line  62  is formed with the same material and through the same process as the gate line  14  (of  FIG. 2 ). 
     During manufacturing, a plurality of liquid crystal panels are arranged with the injection holes  58  facing upward, and one side of the liquid crystal panels are rubbed with sealing material using a roller which has sealing material thereon. The sealing material permeates inside of the injection hole  58  by a capillary phenomenon. The sealing material of the adhesive pattern  60  is hardened by irradiating UV (ultra violet) light and thus able to seal the injection hole  58 . Generally, the UV light is irradiated from the first substrate  52  to the second substrate  54 , so a portion of the adhesive pattern  60  overlapping with the common line  62  is uncured. 
       FIGS. 4A and 4B  are schematic views illustrating a region of an injection hole for an LCD device according to the related art.  FIG. 4A  is an expanded view of an area “IVa” of  FIG. 3 , and  FIG. 4B  is a cross-sectional view taken along a line “IVb-IVb” of  FIG. 4A . 
     In  FIGS. 4A and 4B , the injection hole  58  of the conductive seal pattern  56  is sealed by the adhesive pattern  60 . That is, the liquid crystal layer “LC” can be shielded from outside by the adhesive pattern  60 . As explained above, the adhesive pattern  60  can properly act as a sealing means when the adhesive pattern  60  is completely hardened. However, the adhesive pattern  60  cannot be completely hardened because the adhesive pattern  60  overlaps with the common line  62  which is disposed at an irradiating direction of the UV light. Therefore, the adhesive pattern  60  is partially hardened due to the common line  62 , so the adhesive pattern  60  may mix with the liquid crystal layer “LC.” Even if the UV light is irradiated toward the second substrate  54 , a black matrix  66  on the second substrate  54  shields the adhesive pattern  60 . 
     Therefore, the adhesive pattern  60  is not completely hardened after hardening process, so the uncured portion of the adhesive pattern  60  may be mixed with a portion of the liquid crystal layer “LC” contacting the adhesive pattern  60 . Accordingly, the adhesive pattern  60  acts as impurities in the liquid crystal layer “LC,” so an image defect occurs such as light leakage or screen stain. 
     Specifically, as shown in  FIG. 4B , the common line  62  is formed on the first substrate  52 , the conductive seal pattern  56  including the injection hole  58  and the adhesive pattern  60  in the injection hole  58  are formed on the common line  62 . 
     A black matrix  66  is formed on the second substrate  54  and a common electrode  68  is formed on the black matrix  66 . That is, the conductive seal pattern  56  and the adhesive pattern  60  are disposed between the common line  62  and the common electrode  68 . As shown in  FIG. 4B , the UV light does not reach the adhesive pattern  60  because the common line  62  interrupts irradiation of the UV light onto the adhesive pattern  60 . 
     SUMMARY 
     In one embodiment, a liquid crystal display (LCD) device includes: a first substrate opposite a second substrate and coupled to the second substrate by a first seal pattern; a liquid crystal layer interposed between the first and second substrates within the first seal pattern; a second seal pattern sealing an injection hole in the first seal pattern; and a common line disposed at a first surface of the first substrate and having a predetermined pattern that exposes the second seal pattern to a second surface of the first substrate. 
     In another embodiment, a method of fabricating a liquid crystal display device includes; forming a common line with a predetermined pattern on a first surface of a first substrate; coupling the first substrate with a second substrate using a first seal pattern; injecting a liquid crystal layer between the first and second substrates through an injection hole in the first seal pattern; sealing the injection hole with a second seal pattern; and hardening the second seal pattern; wherein the predetermined pattern exposes the second seal pattern to reduce a blocking of the second seal pattern by the common line. 
     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 
       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: 
         FIG. 1  is a schematic perspective view illustrating an LCD device according to the related art; 
         FIG. 2  is a schematic plan view illustrating an array substrate for an LCD device according to the related art; 
         FIG. 3  is a schematic plan view illustrating an LCD device according to the related art; 
         FIGS. 4A and 4B  are schematic views illustrating a region of an injection hole for an LCD device according to the related art; 
         FIG. 5  is a schematic plan view illustrating an LCD device according to an embodiment of the present invention; 
         FIG. 6  is an expanded view of an area “VI” of  FIG. 5  according to an embodiment of the present invention; 
         FIGS. 7 and 8  are schematic plan view illustrating a region of an injection hole of an LCD device according to embodiments of the present invention; 
         FIG. 9  is a schematic cross-sectional view taken along a line “IX-IX” of  FIG. 6  according to an embodiment of the present invention; and 
         FIGS. 10A and 10B  are cross-sectional views illustrating an LCD device according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the illustrated embodiment of the present invention, which is illustrated in the accompanying drawings. Wherever possible, similar reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIG. 5  is a schematic plan view illustrating an LCD device according to an embodiment of the present invention.  FIG. 6  is an expanded view of an area “VI” of  FIG. 5  according to an embodiment of the present invention. 
     In  FIGS. 5 and 6 , the LCD device  100  includes first and second substrates  102  and  104  attached with a first seal pattern  106 , and a liquid crystal layer  120  is interposed within the first seal pattern  106  between the first and second substrates  102  and  104 . Specifically, the first seal pattern  106  includes an injection hole  108 , and the injection hole  108  is sealed using a second seal pattern  110  after injecting the liquid crystal layer  120 . In particular, the first seal pattern  106  includes a conductive sealant that has a glass fiber and a conductive ball which includes gold (Au). 
     The LCD device  100  has a display region “DA” and a non-display region “NDA” in a periphery of the display region “DA.” 
     For example, when the first substrate  102  is an array substrate and the second substrate  104  is a color filter substrate, the first substrate  102  protrudes beyond from the second substrate  104 . In the protruded portion of the first substrate  102 , although not shown, a driving circuit is connected to the gate and data pads “GP and DP” ( FIG. 2 ) and a connector (not shown) is connected to a PCB (not shown). The connector is connected to the driving circuit to transfer signals from the PCB. However, although the protruded portion of the first substrate  102  is defined at two sides of the first substrate  102  as shown in  FIG. 5 , the protruded portion of the first substrate  102  may be defined at one side of the first substrate  102 . In other words, the driving circuits may be formed at one side of the first substrate  102  in the non-display region “NDA.” 
     The liquid crystal layer  120  can maintain its shape by the first seal pattern  106 . Further, a common line  112  surrounds a boundary between the display region “DA” and the non-display region “NDA” to contact the first seal pattern  106 . 
     In particular, the common line  112  has a convex pattern “CP 1 ” at the injection hole  108  to expose the second seal pattern  110  toward the first substrate  102 . Accordingly, the second seal pattern  110  can be completely hardened through the curing process because the UV light is directly passed onto the second seal pattern  110  without any metal pattern between the first substrate  102  and the second seal pattern  110 . That is, because the second seal pattern does not have an uncured portion, an image defect due to the uncured portion of the second seal pattern  110  does not occur. 
     In accordance with the illustrated embodiment, the common line  112  has a closed shape without an opening. If the common line  112  has an opening, static electricity between facing portions of the common line  112  at the opening may be generated. Therefore, the common line  112  that is electrically connected to a common electrode (not shown) using the first seal pattern of the conductive sealant should have a closed shape to prevent the image defect due to the static electricity. 
       FIGS. 7 and 8  are schematic plan views illustrating a region of an injection hole of an LCD device according to embodiments of the present invention. 
     In  FIG. 7 , a common line  218  includes a concave pattern “CP 2 ” that is bent toward the display region “DA” to expose a second seal pattern  280 . 
     Alternatively, as shown in  FIG. 8 , a common line  318  has a slit portion “SP” including a plurality of slits  320  at a portion of an injection hole  352  to partially expose a second seal pattern  380 . Specifically, the second seal pattern  380  can be completely hardened by diffraction exposing due to the plurality of slits  320  without an uncured portion. 
       FIG. 9  is a schematic cross-sectional view taken along a line “IX-IX” of  FIG. 6  according to an embodiment of the present invention. 
     In  FIG. 9 , the common line  112  including the convex pattern “CP 1 ” is formed on an inner surface of the first substrate  102 , the first seal pattern  106  including the injection hole  108  is formed on the common line  112  and the first substrate  102 , and the second seal pattern  110  is formed at the injection hole  108 . A black matrix  410  is formed on an inner surface of the second substrate  104 , and a common electrode  412  is formed on the black matrix  410 . Although not shown, a color filter layer (not shown) is formed between the black matrix  410  and the common electrode  412  in the display region “DA” ( FIG. 5 ). 
     As shown in  FIG. 9 , the common line  112  does not shield the second seal pattern  110 , so UV light can be reached to the second seal pattern  110  without any metal line between the first substrate  102  and the second seal pattern  104 . Accordingly, the second seal pattern  110  can be completely hardened. 
       FIGS. 10A and 10B  are cross-sectional views illustrating an LCD device according to an embodiment of the present invention.  FIG. 10A  is a view taken along a line “X-X” of  FIG. 5 , and  FIG. 10B  is a view illustrating a display region of the LCD device. 
     In  FIG. 10A , the common line  112  is formed on the inner surface of the first substrate  102 , and the first seal pattern  106  contacts the common line  112 . Further, a black matrix  510  is formed on the inner surface of the second substrate  104 , a dummy color filter pattern  512  is formed on the black matrix  510 , and the common electrode  514  is formed on the dummy color filter pattern  512 . Although not shown, the first seal pattern  106  includes a glass fiber and a conductive ball  600  which includes gold (Au). That is, the first seal pattern  106  can electrically connect the common line  112  and the common electrode  514  using the conductive ball  600  therein. 
     In  FIG. 10B , a thin film transistor “T,” which includes a gate electrode  550 , a semiconductor layer  552 , source and drain electrodes  554  and  556 , is formed on an inner surface of the first substrate  102 , and a pixel electrode  558  is connected to the thin film transistor “T” in the pixel region “P.” Further, the black matrix  510  is formed on the inner surface of the second substrate  104 , a color filter layer  520  is formed on the black matrix  510  in the pixel region “P,” and the common electrode  514  is formed on the color filter layer  520 . Here, the dummy color filter pattern  512  (of  FIG. 10A ) does not act as the color filter layer  520 , but the dummy color filter pattern  512  is formed with the same material as the color filter layer  520 . However, the color filter layer  520  may be formed on the first substrate  102  and not on the second substrate  104 . Further, the dummy color filter pattern  512  may be omitted as shown in  FIG. 9 . 
     As illustrated in  FIG. 10B , a gate insulating layer  551  is formed between the gate electrode  550  and the semiconductor layer  552 , and a passivation layer  557  is formed between the thin film transistor “T” and the pixel electrode  558 . The gate insulating layer  551  and the passivation layer  557  are formed between the common line  112  and the first seal pattern  106  and have a contact hole  559  that exposes a portion of the common line  112  to connect the common line  112  and the first seal pattern  106  as shown in  FIG. 10A . 
     That is, the common line  112  and the gate electrode  550  are formed with the same material on the same layer as each other. However, the common line  112  may be formed with a different material on a different layer from the gate electrode  550 . 
     Although not shown, a gate line is connected to the gate electrode  550  along a first direction, and a gate pad is formed at an end portion of the gate line. Further, a data line is connected to the source electrode along a second direction crossing the first direction to define the pixel region “P,” and a data pad is formed at an end portion of the data line. For example, a portion of the gate line crossing the common line  112  is formed with the same material as the data line to prevent shorting between the common line  112  and the gate line. For example, the gate line and the gate pad are connected to a gate link line of the same material as the data line at an overlapped portion with the common line  112 . 
     Although not shown, a method for fabricating the LCD device may include forming the common line on the first substrate, forming the first seal pattern including the injection hole on the common line, forming a common electrode on a second substrate, attaching the first and second substrates with the first seal pattern, injecting a liquid crystal layer into the injection hole, sealing the injection hole using a second seal pattern, and curing the second seal pattern toward the first substrate, wherein the common line exposes the second seal pattern toward the first substrate. 
     According to the LCD device, since the common line does not overlap with the second seal pattern, the second seal pattern is completely hardened. Therefore, image defects such as light leakage or screen stain due to the uncured second seal pattern are not generated. Therefore, a high image quality can be obtained. 
     While the invention has been particularly shown and described with reference to an illustrated embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.