Abstract:
An exemplary liquid crystal panel ( 10 ) includes an upper substrate ( 12 ), a lower substrate ( 14 ) located opposite to the upper substrate, a liquid crystal layer ( 15 ) located between the upper substrate and the lower substrate, and a plurality of spacers ( 16 ). The lower substrate includes a plurality of thin film transistors ( 145 ) formed thereat. The spacers adjoin top portions of the thin film transistors and extend to the upper substrate respectively. The spacers are configured for absorbing light beams passing through the thin film transistors.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a liquid crystal panel that includes a plurality of light absorbing spacers adjoining thin film transistors (TFTs), and a liquid crystal display (LCD) including the liquid crystal panel. 
       GENERAL BACKGROUND 
       [0002]    Liquid crystal displays are commonly used as display devices for compact electronic apparatuses, because they not only provide good quality images but are also very thin. A major component of a typical liquid crystal display is a liquid crystal panel. 
         [0003]    Referring to  FIG. 7 , a typical liquid crystal panel  70  includes an upper substrate  72 , a lower substrate  74  located opposite to the upper substrate  72 , a liquid crystal layer  75  located between the upper substrate  72  and the lower substrate  74 , and a plurality of spacers  76  (only one shown) spacing the upper substrate  72  and the lower substrate  74 . 
         [0004]    In the liquid crystal panel  70 , a plurality of TFTs  77  are formed on a top surface (not labeled) of the lower substrate  74 , and a plurality of black matrix units  78  are formed on a bottom surface (not labeled) of the upper substrate  72 . The black matrix units  78  respectively correspond to the TFTs  77 , and are separated from the TFTs  77 . 
         [0005]    Light beams passing through the TFTs  77  are liable to be scattered and thereby bypass the corresponding black matrix units  78 . This can make it difficult to accurately control the gradation levels of luminance of the liquid crystal panel  70 . In addition, due to inherent limitations in manufacturing of the liquid crystal panel  70 , it is problematic to accurately align the black matrix units  78  with their respective TFTs  77 . Therefore an area of each black matrix unit  78  generally needs to be greater than a desired minimum area, in order that the black matrix units  78  can absorb a sufficiently large amount of light beams propagating from the TFTs  77 . Thus an aperture ratio of the liquid crystal panel  70  is reduced, and the optical performance of the liquid crystal panel  70  is liable to be impaired. 
         [0006]    What is needed, therefore, is a liquid crystal panel that can overcome the above-described deficiencies. What is also needed is a liquid crystal display including the liquid crystal panel. 
       SUMMARY 
       [0007]    In one preferred embodiment, a liquid crystal panel includes an upper substrate, a lower substrate located opposite to the upper substrate, a liquid crystal layer located between the upper substrate and the lower substrate, and a plurality of first black matrix units. The lower substrate includes a plurality of thin film transistors formed thereat. The spacers adjoin top portions of the thin film transistors and extend to the upper substrate respectively. The spacers are configured for absorbing light beams passing through the thin film transistors. 
         [0008]    Other aspects, novel features and advantages will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of at least one embodiment of the present invention. In the drawings, like reference numerals designate corresponding parts throughout various views, and all the views are schematic. 
           [0010]      FIG. 1  is a simplified, side cross-sectional view of part of a liquid crystal panel according to a first embodiment of the present invention, the liquid crystal panel including a transparent upper substrate and a transparent lower substrate. 
           [0011]      FIG. 2  is an abbreviated, top-down, plan view of the lower substrate of the liquid crystal panel of  FIG. 1 . 
           [0012]      FIG. 3  is an abbreviated, top-down, plan view of the upper substrate of the liquid crystal panel of  FIG. 1 , showing color units and black matrix units located on an underside of the upper substrate and visible through the upper substrate. 
           [0013]      FIG. 4  is an abbreviated, top-down, plan view of a transparent upper substrate of a liquid crystal panel according to a second embodiment of the present invention, showing color units and black matrix units located on an underside of the upper substrate and visible through the upper substrate. 
           [0014]      FIG. 5  is a simplified, side cross-sectional view of part of a liquid crystal panel according to a third embodiment of the present invention. 
           [0015]      FIG. 6  is an exploded, side-on plan view of a liquid crystal display including the liquid crystal panel of  FIG. 1 . 
           [0016]      FIG. 7  is a side, cross-sectional view of part of a conventional liquid crystal panel. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0017]    Reference will now be made to the drawings to describe preferred embodiments of the present invention in detail. 
         [0018]    Referring to  FIG. 1 , a liquid crystal panel  10  according to a first embodiment of the present invention is shown. The liquid crystal panel  10  includes an upper substrate  12 , a lower substrate  14  located opposite to the upper substrate  12 , and a liquid crystal layer  15  located between the upper substrate  12  and the lower substrate  14 . The upper substrate  12  and the lower substrate  14  are both transparent, and are generally made from glass or quartz. 
         [0019]    Referring also to  FIG. 2 , the lower substrate  14  includes a plurality of scanning lines  142  that are parallel to each other and that each extend along a first direction, and a plurality of signal lines  144  that are parallel to each other and that each extend along a second direction orthogonal to the first direction. The lower substrate  14  also includes a plurality of TFTs  145  that function as switching elements. The lower substrate  14  further includes a plurality of pixel electrodes  146  formed on a surface thereof facing toward the upper substrate  12 . Each TFT  145  is provided in the vicinity of a respective point of intersection of the scanning lines  142  and the signal lines  144 . 
         [0020]    Each TFT  145  includes a gate electrode  147 , a source electrode  148 , and a drain electrode  149 . The gate electrode  147  of the TFT  145  is connected to the corresponding scanning line  142 . The source electrode  148  of the TFT  145  is connected to the corresponding signal line  144 . The drain electrode  149  of the TFT  145  is connected to a corresponding pixel electrode  146 . 
         [0021]    A plurality of first black matrix units  16  respectively extend from top portions (not labeled) of the TFTs  145 , and reach an underside of the upper substrate  12 . Each first black matrix unit  16  adjoins and covers the top portion of the respective TFT  145 , and is fixed relative to the respective TFT  145 . Thus, the upper substrate  12  and the lower substrate  14  are spaced from each other by the first black matrix units  16 . In the illustrated embodiment, each first black matrix unit  16  has an essentially rectangular cross-sectional configuration. For example, each first black matrix unit  16  has an essentially cylindrical configuration. The first black matrix units  16  can be applied onto the respective TFTs  145  using a coating method. The first black matrix units  16  are generally made from light-sensitive black resin. 
         [0022]    Referring also to  FIG. 3 , the upper substrate  12  includes a plurality of color units  124  and a plurality of second black matrix units  126  located on a bottom portion thereof. For example, the color units  124  and second black matrix units  126  are arranged on an underside of the upper substrate  12 . The color units  124  are a plurality of red, green, and blue (RGB) color units arrayed in a predetermined pattern. The color units  124  respectively correspond to the pixel electrodes  146  of the lower substrate  14 , and are each spaced from their neighboring color units  124  by the second black matrix units  126  to avoid color mixing. The second black matrix units  126  respectively correspond to the scanning lines  142 , the signal lines  144  and the TFTs  145  on the lower substrate  14 . Portions of the second black matrix units  126  contact the respective first black matrix units  16 . When the liquid crystal panel  10  is manufactured, the first black matrix units  16  and the second black matrix units  126  are formed in separate processes. 
         [0023]    With the above-described configuration, light beams passing up through the TFTs  145  can be completely absorbed by the first black matrix units  16  even when the upper substrate  12  is not aligned with the lower substrate  14  very accurately. Thus, undesired variations in gradation levels of luminance of the liquid crystal panel  10  are avoided. In addition, the first black matrix units  16  cover the respective TFTs  145 , and are immobile relative to the respective TFTs  145 . Thus, there is no need to align the first black matrix units  16  with the respective TFTs  145  in manufacturing of the liquid crystal panel  10 . Furthermore, a distance between the upper substrate  12  and the lower substrate  14  is maintained at an essentially constant value, thus avoiding undesired optical errors in the liquid crystal panel  10 . 
         [0024]    Referring to  FIG. 4 , a liquid crystal panel  20  according to a second embodiment of the present invention is similar to the liquid crystal panel  10 . The liquid crystal panel  20  includes an upper substrate  22  having a plurality of color units  224  and a plurality of black matrix units  226  formed on an underside thereof. The black matrix units  226  space neighboring color units  224  apart from each other, in order to avoid color mixing. The black matrix units  226  respectively correspond to scanning lines (not shown) and signal lines (not shown) of a lower substrate (not shown) located opposite to the upper substrate  22  of the liquid crystal panel  20 . The liquid crystal panel  20  can achieve advantages similar to those of the liquid crystal panel  10 . 
         [0025]    Referring to  FIG. 5 , a liquid crystal panel  30  according to a third embodiment of the present invention is similar to the liquid crystal panel  10 . However, the liquid crystal panel  30  includes a plurality of first black matrix units  36  respectively adjoining a plurality of TFTs  345  formed on a lower substrate  34 . Each first black matrix unit  36  has an essentially trapezoidal cross-sectional configuration. In the illustrated embodiment, each first black matrix unit  36  has an essentially isosceles trapezoidal cross-sectional configuration. For example, the first black matrix unit  36  can be frusto-conical or frusto-pyramidal. The liquid crystal panel  30  can achieve advantages similar to those of the liquid crystal panel  10 . 
         [0026]    Referring to  FIG. 6 , a liquid crystal display  1  having the liquid crystal panel  10  is shown. The liquid crystal display  1  includes the liquid crystal panel  10  and a backlight module  100 . The backlight module  100  is located adjacent to the lower substrate  14  of the liquid crystal panel  10 . In alternative embodiments, the liquid crystal panel  10  can be replaced with either of the above-described liquid crystal panels  20 ,  30 . 
         [0027]    It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit or scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.