Abstract:
A liquid crystal display (LCD) of reduced reflection phenomenon is provided. The data lines and gate lines of the LCD have an anti-reflection layer thereon. The anti-reflection layer decreases ambient light reflection. Thus, the CONTRAST of the LCD is improved.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims priority of Taiwan Patent Application Serial No. 092100646 filed on Jan. 13, 2003.  
         FIELD OF INVENTION  
         [0002]    The present invention relates to a liquid crystal display (LCD) of reduced reflection phenomenon.  
         BACKGROUND OF THE INVENTION  
         [0003]    The reflection of ambient light from an LCD panel would reduce CONTRAST of the liquid crystal display. To increase the CONTRAST, a black matrix layer is disposed inside the liquid crystal display to block the ambient light. The black matrix layer may also cover the area where the liquid crystal is not ordered enough to elevate image quality.  
           [0004]    [0004]FIG. 1 shows a cross-sectional diagram of a liquid crystal display according to the prior art. A polysilicon layer  128  and an insulator layer  106  are disposed on a first substrate  102 . A gate  126  is formed by an extension of a gate line (not shown). An interlayer dielectric layer  108  is formed on the gate  126  and the insulator layer  106 . Source/drains  122 ,  124  are selectively formed by an extension of a data line (not shown). The source/drains  122 ,  124  are disposed on the interlayer dielectric layer  108  and contact the polysilicon layer  128 . The source/drains  122 ,  124  and the gate  126  form a transistor. A planarization layer  110  is formed on the interlayer dielectric layer  108  and the source/drains  122 ,  124 . A pixel electrode  112  is formed on the planarization layer  110 , and electrically connected to the source/drain  124 . Color filters  114  are disposed on a second substrate  104 . A black matrix layer  120  is located on the second substrate  104  and lies between the color filters  114 . A liquid crystal layer  118  is located between the pixel electrode  112  and color filters  114 .  
           [0005]    The source/drains  122 ,  124  and the gate  126  are typically formed by metal, which generally has high reflectivity. The first substrate  102  has to be aligned with the second substrate  104  to ensure that the source/drains  122 ,  124  and the gate  126  are covered by the black matrix layer  120 , so that reflection phenomenon is reduced. To cover the source/drains  122 ,  124  and the gate  126  effectively, typically, the area of the black matrix layer  120  is large. However, larger black matrix area would result in smaller aperture ratio.  
         SUMMARY OF THE INVENTION  
         [0006]    One aspect of the present invention provides a liquid crystal display having anti-reflection layer for reducing reflection phenomenon of the liquid crystal display.  
           [0007]    A liquid crystal display of reduced reflection phenomenon, including a first substrate and a second substrate, is provided. A switch is disposed on the first substrate to control brightness of the liquid crystal display. A data line has an extension to selectively form source/drains of the switch. A first electrode is electrically connected to the data line. An anti-reflection layer of an anti-reflection material is disposed on the data line to reduce reflection phenomenon of the liquid crystal display. A second electrode is disposed on the second substrate. And a liquid crystal layer is disposed between the second electrode and the switch.  
           [0008]    A liquid crystal display of reduced reflection phenomenon, including a first substrate and a second substrate, is provided. A switch is disposed on the first substrate to control brightness of the liquid crystal display. A gate line has an extension to form a gate of the switch. A first electrode is electrically connected to the data line. An anti-reflection layer of an anti-reflection material is disposed on the gate line to reduce reflection phenomenon of the liquid crystal display. A second electrode is disposed on the second substrate. And a liquid crystal layer is disposed between the second electrode and the switch. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    For a more complete understanding of the present invention, and the advantage thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:  
         [0010]    [0010]FIG. 1 is a cross-sectional diagram of a liquid crystal display according to the prior art, which has a black matrix layer and a data line;  
         [0011]    [0011]FIG. 2 is a schematic diagram showing a relative position of a data line and a gate line of an exemplary embodiment;  
         [0012]    [0012]FIG. 3 is a cross-sectional diagram of a first exemplary embodiment, in which a data line has an anti-reflection layer and a color filter is disposed on a second substrate;  
         [0013]    [0013]FIG. 4 is a cross-sectional diagram of a second exemplary embodiment, in which a data line has an anti-reflection layer and a color filter is disposed on a first substrate;  
         [0014]    [0014]FIG. 5 is a cross-sectional diagram of a third exemplary embodiment, in which a data line has an anti-reflection layer and a color filter is disposed on a first substrate;  
         [0015]    [0015]FIG. 6 is a cross-sectional diagram of a fourth exemplary embodiment, in which a gate line has an anti-reflection layer; and  
         [0016]    [0016]FIG. 7 is a cross-sectional diagram of a fifth exemplary embodiment, in which both a data line and a gate line have an anti-reflection layer. 
     
    
     DETAILED DESCRIPTION  
       [0017]    A liquid crystal display having an anti-reflection layer is provided. The anti-reflection layer is disposed on a data line or a gate line to reduce reflection phenomenon and elevate CONTRAST.  
         [0018]    [0018]FIG. 2 is a schematic diagram showing a relative position of a data line and a gate line of an exemplary embodiment. The data line  202  and the gate line  204  are staggered to each other. The data line  202  has an extension to selectively form source/drains  206 ,  208 . The gate line  204  has an extension to form a gate  210 . A pixel electrode  212  is electrically connected to the source/drain  208 . The anti-reflection layer of the present invention may be formed on one of or both the data line  206  and the gate line  208 .  
         [0019]    [0019]FIG. 3 is a cross-sectional diagram of a first exemplary embodiment. The first substrate  302  and the second substrate  304  may be glass substrates or similar. A semiconductor layer  328 , preferably being a polysilicon layer or an amorphous silicon layer, is disposed on the first substrate  302 . An insulator layer  306  is located on the semiconductor layer  328 . A gate  326  formed by an extension of a gate line is disposed on the insulator layer  306 . An interlayer dielectric layer  308  is formed on the gate  326  and the first substrate  302 . Source/drains  322 ,  324  selectively formed by an extension of the data line, are disposed on the interlayer dielectric layer  308  and contact the semiconductor layer  328 . The gate  326 , the source/drains  322 ,  324  form a switch, e.g. thin film transistor. A planarization layer  310  is formed on the interlayer dielectric layer  308  and the source/drains  322 ,  324 . A first electrode  312 , namely pixel electrode, is formed on the planarization layer  310  and electrically connected to the source/drain  324 . The first electrode  312  is preferably composed of Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), or similar.  
         [0020]    With continued reference to FIG. 3, an anti-reflection layer  320  is disposed on the source/drain  322 . The anti-reflection layer  320  has the same pattern as the data line and the source/drain  322 . Therefore, no additional optical mask is needed to fabricate the anti-reflection layer  320 . The anti-reflection layer  320  is composed of anti-reflection material, which may reduce reflection inside the liquid crystal display. The anti-reflection material may preferably be chromium oxide, silicon nitride, or other appropriate reflection-reducing material. Color filters  314  may be formed on the second substrate  304  to form color display. A second electrode  316  is formed on the color filters  314 . The second electrode  316 , also known as common electrode, is preferably composed of ITO or similar. A liquid crystal layer  318  is located between the second electrode  316  and the planarization layer  310 . In the first exemplary embodiment, the anti-reflection layer  320  is formed directly on the source/drain  322 . Therefore, no excess area of the anti-reflection layer  320  is needed to cover the source/drain  322 , and the aperture ratio may be effectively raised.  
         [0021]    [0021]FIG. 4 is a cross-sectional diagram of a second exemplary embodiment. The main difference between the first and second exemplary embodiments is that the color filter  414  is formed directly on the first electrode  312 . As shown in FIG. 4, the first electrode  312  is located between the color filter  414  and the planarization layer  310 . And the second electrode  416  is formed directly on the second substrate  304 . In the second exemplary embodiment, the color filter  414  is formed directly on the first electrode  312 . Therefore, it would not be necessary to align the color filter  414  with the first substrate  302 , which is required for the first exemplary embodiment.  
         [0022]    [0022]FIG. 5 is a cross-sectional diagram of a third exemplary embodiment. The main differences between the second and third exemplary embodiments are that the color filter  414  is formed directly on the planarization layer  310  and the first electrode  412  is formed on the color filter  414 .  
         [0023]    [0023]FIG. 6 is a cross-sectional diagram of a fourth exemplary embodiment. The main difference between the first and fourth exemplary embodiments is that the anti-reflection layer  420  is formed on the gate  326 . The anti-reflection layer  420  is composed of anti-reflection material, which may reduce reflection inside the liquid crystal display. The anti-reflection material may preferably be chromium oxide, silicon nitride, or other appropriate reflection-reducing material. The anti-reflection layer  420  has the same pattern as the gate line and the gate  326 . Therefore, no additional optical mask is needed to fabricate the anti-reflection layer  420 . For the fourth exemplary embodiment, the color filter  314  may also locate directly on the first electrode  312  or the planarization layer  310 , as shown in FIG. 4 and FIG. 5.  
         [0024]    [0024]FIG. 7 is a cross-sectional diagram of a fifth exemplary embodiment. Being different from the first and fourth exemplary embodiments, both anti-reflection layers  320  and  420  are formed. Then the reflection inside the liquid crystal display is effectively reduced and the CONTRAST is elevated. For the fifth exemplary embodiment, the color filter  314  may also locate directly on the first electrode  312  or the planarization layer  310 , as shown in FIG. 4 and FIG. 5.  
         [0025]    Though the embodiments described herein adopt the top-gate structure, other structures, such as the bottom-gate structure, may still be suitable for this invention.  
         [0026]    While this invention has been described with reference to the illustrative embodiments, these descriptions should not be construed in a limiting sense. Various modifications of the illustrative embodiment, as well as other embodiments of the invention, will be apparent upon reference to these descriptions. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as falling within the true scope of the invention and its legal equivalents.