Abstract:
A liquid crystal display device ( 300 ) includes a first substrate ( 35 ), a color filter ( 38 ) having a black frame ( 39 ), a sealing member ( 34 ) and a second substrate ( 33 ). The first substrate combines with the second substrate to form a cavity. The color filter is attached on an inner surface of the first substrate. The black frame has a patterned design and is arranged along an outer periphery of the color filter. The sealing member is formed on an area of the black frame, located on the black frame. The sealing member attaches the first and the second substrates together.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention generally relates to a liquid crystal display (LCD) device and a method of manufacturing the same.  
           [0003]    2. The Related Art  
           [0004]    In general, an LCD device has the advantages of thinness, light weight, and low power consumption. For that reason, LCD devices are widely used in various types of electronic equipment, from pocket calculators to large-scale office automation equipment.  
           [0005]    The basic structure of an LCD device is shown in FIG. 8. The LCD device  100  comprises a thin layer of liquid crystal  12  retained between two substrates  13 ,  15  attached together by a sealing member  14 . A TFT (Thin Film Transistor) layer  11  is formed on an inner surface of the substrate  13 . The substrate  15  opposite to the substrate  13  has a color filter  18  matching with the TFT layer  11 . The color filter  18  includes a black matrix  181  for shielding light and color layers  182  alternately positioned within the black matrix  181 . A plurality of wires  17  extend from the TFT layer  11  and through the sealing member  14 , which are electrically connected with a driving circuit (not labeled).  
           [0006]    The black matrix has a wide black frame  19  integrally formed therewith, for improving brightness contrast. The black frame  19  surrounds the color layers  182  and is disposed between the color layers  182  and the sealing member  14 .  
           [0007]    In manufacture of an LCD device, the most generally used method of filling the liquid crystal into the cavity formed between the two substrates  13 ,  15  is the vacuum insertion method. However, the method has various disadvantages, such as the lengthy period of time required to complete the process of filling the cavity with the liquid crystal.  
           [0008]    For that reason, another method of filling the cavity, the so-called “One Drop Fill” (ODF) method was recently published. However, the problem with the LCD device  100  manufactured by this ODF method is that the sealing member  14  adhering to the substrate  15  and separated from the black frame  19  makes an area of the LCD device  100  unnecessarily large. The cause of the problem will be described in detail.  
           [0009]    In manufacture of the LCD device  100  using the ODF method, the liquid crystal is dropped onto either one of the two substrates  13 ,  15  within the bounds described by the sealing member  14 , which is formed on a peripheral region of the substrate. At this stage the sealing member  14  is not polymerized. The conventional heat-treatment method of hardening or polymerizing the sealing member  14  is generally not applicable since high temperatures would be detrimental to the liquid crystal between the two substrates  13 ,  15 . Instead of thermal curing, the sealing member  14  is polymerized and hardened by photo-curing using ultraviolet (UV) radiation irradiating through other of the two substrates  13 ,  15 .  
           [0010]    Experience has shown that any uncured or partially cured sealing member  14  can cause serious contamination of the liquid crystal and can lead to a long term degradation of the LCD device  100 . So, to fully harden the sealing member  14  using photo-curing, the sealing member  14  has to be separated from the black frame  19  on the inner surface of the substrate  15  to allow enough UV light radiation to transmit through the second substrate  15  to photo-cure the sealing member  14 . Thus, an area of the LCD device  100  is larger than it otherwise would be.  
           [0011]    Therefore, an LCD device with a more efficient area utilization is desired.  
         SUMMARY OF THE INVENTION  
         [0012]    An object of the present invention is to provide a liquid crystal display device having a high brightness contrast and a more efficient area utilization.  
           [0013]    Another object of the present invention is to provide a method of manufacturing the above-described liquid crystal display device.  
           [0014]    A liquid crystal display device includes a first substrate, a color filter having a black frame, a sealing member, and a second substrate. The first substrate combines with the second substrate to form a cavity. The color filter is attached on an inner surface of the first substrate. The black frame has a patterned design and is arranged along an outer periphery of the color filter. The sealing member is deposited on the area of the black frame, over the black frame, and the sealing member attaches the first and the second substrates together.  
           [0015]    A method of manufacturing a liquid crystal display device comprises the steps of preparing a first substrate and a second substrate; forming a black matrix on the first substrate, the black matrix having a patterned black frame around a periphery thereof; forming a sealing member with a closed periphery on the black frame; dropping liquid crystal on an area of the first substrate within the bounds of the sealing member; placing the second substrate on the sealing member and aligning the first substrate and the second substrate; and curing the sealing member using light shining through the first substrate to cure the sealing member.  
           [0016]    Other objects, advantages, and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a cross-sectional view of an LCD device according to the present invention;  
         [0018]    [0018]FIG. 2 is a cross-sectional view taken along the line of  2 - 2  in FIG. 1;  
         [0019]    [0019]FIG. 3 is a cross-sectional view taken along the line of  3 - 3  in FIG. 1;  
         [0020]    [0020]FIG. 4 is an essential optical paths diagram of light being blocked in the LCD device in FIG. 3;  
         [0021]    [0021]FIG. 5 is a flow chart of manufacturing the first embodiment of LCD device in FIG. 1 according to the present invention;  
         [0022]    [0022]FIG. 6 is an essential optical paths diagram of exposing a sealing member of the LCD device in FIG. 3;  
         [0023]    [0023]FIG. 7 is a second embodiment of an LCD device according to the present invention; and  
         [0024]    [0024]FIG. 8 is a cross-sectional view of a prior art LCD device. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    Referring to FIGS. 1-3, a first embodiment of an LCD device  300  includes a first substrate  35 , a sealing member  34 , and a second substrate  33 . The two substrates  33 ,  35  are positioned parallel and opposite to each other. A liquid crystal layer  32  is retained between the two substrates  33 ,  35 . A color filter  38  and a TFT layer  31  are located on the two inner surfaces of the two substrates  35 ,  33  respectively. The TFT layer  31  is opposite to and aligned with the color filter  38 .  
         [0026]    The color filter  38  includes a black matrix  381  for shielding light beams impinging thereon and three primarily color layers (R.B.G)  382  located in spaces of the black matrix  381 . Further more, the color filter  38  also includes a black frame  39  which is an outer periphery of the black matrix  381 . The black frame  39  has a comb-like construction including a plurality of teeth. A width of each tooth of the black frame  39  is wider than a width of each strip making up the majority of the black matrix  381 . The wide teeth improve the brightness contrast of the LCD device  300 . A plurality of wires  37  extends from the edges of the TFT layer  31  and covers a remainder of the inner surface of the second substrate  33 , and passes through the sealing member  34 . The wires  37  are arranged in a comb-like pattern complementary to the plurality of teeth. In other words, the teeth of the wires  37  are positioned in an alternating sequence with the teeth of the black frame  39 , between and juxtaposed with the teeth, but in a different parallel plane from the teeth of the black frame  39 .  
         [0027]    The sealing member  34  is located underneath the black frame  39  formed on an inner surface of the first substrate  35 . The sealing member  34  is made of a photosensitive resin or a mixture of photosensitive and thermosensitive resin.  
         [0028]    Other embodiments of the LCD device may feature the black frame  39  being made of a pattern of squares, or a cross-section of the teeth of the black frame  39  having a shape of a parallelogram (see FIG. 7).  
         [0029]    The advantage of the LCD device  300  is that it utilizes the area occupied more efficiently since the sealing member  34  is located underneath the black frame  39 .  
         [0030]    Referring to FIG. 4, when in use with a back light, light can not pass through the black frame  39  and the wires  37  since the wires  37  and teeth of the comb-like black frame  39  are in alternating masking relation to one another. So the LCD device  300  retains a good brightness contrast and performance.  
         [0031]    Referring also to FIG. 5, a first embodiment of a method of manufacturing the LCD device  300  includes: preparing a first substrate  35  and a second substrate  33 ; attaching a TFT layer  31  on the surface of the second substrate  33 ; forming a plurality of wires  37  electrically and mechanically connecting to edges of the TFT layer  31  and extending on the surface of the second substrate  33 ; forming the black matrix  381  on the first substrate  35 , the black matrix  381  having a patterned black frame  39  around a periphery thereof; filling the three primarily color layers (R.B.G)  382  into the spaces of the black matrix  381 ; forming a sealing member  34  with a closed periphery on the black frame  39 ; dropping liquid crystal on an area of the first substrate  35  within the bounds of the sealing member  34 ; placing the second substrate  33  on the sealing member  34  and aligning the first substrate  35  and the second substrate  33 ; and curing the sealing member  34  by shining a light through the first substrate  35  to cure the sealing member  34 . In the process of curing the sealing member  34 , the radiative light illuminates the sealing member  34  through spaces of the patterned black frame  39  in variable directions (see FIG. 6.)  
         [0032]    The black frame  39  of the black matrix  381  is fabricated by a photolithography process. The steps in manufacturing the black frame  39  according to a first embodiment include: forming a photosensitive layer on the surface of the first substrate  35 , curing the photosensitive layer, and developing it later to form the black matrix  381  with the black frame  39 .  
         [0033]    The steps in manufacturing the black frame  39  according to a second embodiment include: forming a photosensitive layer on the surface of the first substrate  35 ; exposing the center part of the photosensitive layer through the first substrate  35  to form the center part of the black matrix  381 ; aligning the first substrate  35  and the second substrate  33 ; exposing the remainder part of the photosensitive resin layer through the second substrate  33  using the wires  37  of the second substrate  33  as a photo mask to form the black frame  39  of the black matrix  381 ; developing the photosensitive layer to form the black frame  39 .  
         [0034]    Referring to FIG. 6, light beams can illuminate the first substrate  35  from perpendicular or oblique directions. When the light is from an oblique direction, it can illuminate parts of the sealing member  34  beneath the teeth of the black frame  39 . So that the sealing member  34  can be fully hardened, allowing the LCD device  300  to attain high performance.  
         [0035]    Since the exposing step for fabricating the black frame  39  according to the second embodiment utilizes the wires  37  on the second substrate  33  as a photo mask, the wires  37  and the black frame  39  are in alternating masking relation, thus attain a light blocking capability.  
         [0036]    A third embodiment replaces the photosensitive layer mentioned above with a metal shielding layer that can be etched. The steps in manufacturing the black frame  39  and black matrix  381  include forming a metal shielding layer on the surface of the first substrate  35 ; forming a photoresistive layer on the metal shielding layer; curing and developing the photoresistive layer; and etching the metal shielding layer; thus forming the black matrix  381  with the black frame  39 .  
         [0037]    Advantages of the described embodiments over the prior art include the following. First, the LCD device  300  can utilize the area occupied more efficiently, so can be made smaller. Second, the black frame  39  and the wires  37  can entirely shield the periphery of the back light, thus the LCD device  300  retains a high performance.  
         [0038]    It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.