Abstract:
A liquid crystal display panel comprise a first substrate, a second substrate and a electrode structure. The electrode structure is disposed on the first substrate and defining a pixel. The electrode structure further comprises a first sub-electrode having a first stem electrode with a first end edge and a first branch electrode nearest the first end edge, and a second sub-electrode having a second stem electrode with a second end edge and a second branch electrode nearest the second end edge. The first sub-electrode and the second sub-electrode are adjacent to each other, and the first end edge and the second end edge are adjacent to the same side of the pixel. A first distance between the first end edge and the first branch electrode is different from a second distance between the second end edge and the second branch electrode.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of application Ser. No. 13/889,724, filed May 8, 2013, which is a division of application Ser. No. 12/963,860, filed Dec. 9, 2010 (now U.S. Pat. No. 8,462,304, issued Jun. 11, 2013). This application claims the benefit of Taiwan application Serial No. 98145117, filed Dec. 25, 2009, the disclosures of these earlier applications are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates in general to a liquid crystal display panel, and more particularly to a multi-domain liquid crystal display panel. 
         [0004]    2. Description of the Related Art 
         [0005]    In recent years, display technology has gained significant progress, and the market demand for liquid crystal display is booming. The display quality of a liquid crystal display is essential in the display industry. Currently, wide angle technology has gradually become an important factor in the quality assessment of the liquid crystal display. In the wide angle technology, multi-domain vertical alignment (MVA) technology attracts more and more interest. 
         [0006]    In general, the liquid crystal display includes two polarizers, a liquid crystal display panel and a backlight module. The backlight module is used for providing a light source to the liquid crystal display panel, and the liquid crystal display panel is disposed between the two polarizers. The liquid crystal display panel includes two substrates and a liquid crystal layer which is disposed between the two substrates. Several pixel electrodes are disposed on one of the substrates. To provide multi domains, the pixel electrodes are patterned and divided into regions. Here, the pixel electrode includes two symmetric sub-electrode structures, for example. Each sub-electrode structure includes a stem electrode and several branch electrodes. The branch electrodes are symmetrically connected to the stem electrode. 
         [0007]    Referring to  FIG. 1 , a partial diagram of the liquid crystal pointing arrows corresponding to the liquid crystal layer of a pixel electrode is shown. When a voltage is applied to the pixel electrode, the electrical field changes the directions of the liquid crystal pointing arrows, as indicated in the region Al at the junction between two sub-electrode structures in  FIG. 1 . When the directions of the liquid crystal pointing arrows in the region Al are chaotic to form nodes, streaks will occur to the display frame of the liquid crystal display panel. Therefore, the brightness of the liquid crystal display panel will be decreased during display. Or, the brightness of the liquid crystal display panel may become inconsistent during the display of frames so as to deteriorate the display quality. Besides, the generation of streaks normally increases the time for the liquid crystal display panel to resume the stable state. As a result, how to provide a liquid crystal display with excellent display quality has become an imminent task for the industries. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention is directed to a liquid crystal display panel which reduce the occurrence of streaks, increase the brightness and shorten the time for resuming the stable state so as to improve the display quality and product competitiveness. 
         [0009]    A liquid crystal display panel comprise a first substrate, a second substrate, a liquid crystal layer and a electrode structure is provided. The liquid crystal layer is disposed between the first substrate and the second substrate. The electrode structure is disposed on the first substrate and defining a pixel. The electrode structure further comprises a first sub-electrode having a first stem electrode with a first end edge and a first branch electrode nearest the first end edge, and a second sub-electrode having a second stem electrode with a second end edge and a second branch electrode nearest the second end edge. The first sub-electrode and the second sub-electrode are adjacent to each other. The first end edge and the second end edge are adjacent to the same side of the pixel. A first distance between the first end edge and the first branch electrode is different from a second distance between the second end edge and the second branch electrode. 
         [0010]    The above and other aspects of the invention will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment(s). The following description is made with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  shows a partial diagram of the liquid crystal pointing arrows corresponding to the liquid crystal layer of a pixel electrode; 
           [0012]      FIG. 2A  shows a liquid crystal display device according to a first embodiment of the invention; 
           [0013]      FIG. 2B  shows an electrode structure in  FIG. 2A ; 
           [0014]      FIG. 2C  shows liquid crystal pointing arrows of the liquid crystal layer in  FIG. 2A  corresponding to a region in  FIG. 2B ; 
           [0015]      FIG. 3  shows an electrode structure according to a second embodiment of the invention; 
           [0016]      FIG. 4  shows an electrode structure according to a third embodiment of the invention; 
           [0017]      FIG. 5  shows an electrode structure according to a fourth embodiment of the invention; and 
           [0018]      FIG. 6  shows an electrode structure according to a fifth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The liquid crystal display panel disclosed in the invention are elaboration in a number of embodiments below with accompanying drawings. However, anyone who is skilled in the art of the invention will understand that these drawings and disclosures are for elaboration purpose only, not for limiting the scope of protection of the invention. 
       First Embodiment 
       [0020]    Referring to  FIG. 2A , a liquid crystal display device according to a first embodiment of the invention is shown. The liquid crystal display device includes a liquid crystal display panel  100 , a backlight module  200  and polarizers  310  and  320 . The absorption axes of the polarizers  310  and  320  are perpendicular to each other. The liquid crystal display panel  100  is disposed between the polarizers  310  and  320 . The backlight module  200  is used for providing light for the liquid crystal display panel  100  to display an image. 
         [0021]    The liquid crystal display panel  100  includes a first substrate  110 , a second substrate  120 , an electrode structure  130  and a liquid crystal layer  140 . The second substrate  120  is substantially parallel to the first substrate  110 . The liquid crystal layer  140  is located between the first substrate  110  and the second substrate  120 . The electrode structure  130  is disposed on the first substrate  110 . 
         [0022]    Referring to  FIG. 2B , an electrode structure  130  in  FIG. 2A  is shown. The electrode structure  130  includes a first stem electrode  131   t,  a first branch portion  131   b,  a second stem electrode  132   t  and a second branch portion  132   b.  Let the first stem electrode  131   t  and the first branch portion  131   b  be viewed as a sub-electrode structure S 11 , and the second stem electrode  132   t  and the second branch portion  132   b  be viewed as a sub-electrode structure S 12 , the sub-electrode structures S 11  and S 12  are horizontally adjacent to each other and can respectively be viewed as a first bright region and a second bright region. When an image is displayed, the first bright region and the second bright region can be mixed and displayed in a pixel to produce low color shift effect. Thus, the display quality of the liquid crystal display panel  100  is even more dedicated. 
         [0023]    The first stem electrode  131   t  is, for example, cross-shaped, and the first branch portion  131   b  includes several first branch electrodes  131   b   1 . The first branch electrodes  131   b   1  are connected to the first stem electrode  131   t.  The two adjacent first branch electrodes  131   b   1  are substantially parallel to each other and separated apart by a first interval d 11 . Besides, the second stem electrode  132   t  is, for example, cross-shaped, and the second branch portion  132   b  includes several second branch electrodes  132   b   1 . The second branch electrodes  132   b   1  are connected to the second stem electrode  132   t.  The two adjacent second branch electrodes  132   b   1  are substantially parallel to each other and separated apart by a second interval d 12 . Any of the first branch electrodes  131   b   1  corresponds to at least part of one of the second intervals d 12 , and any of the second branch electrodes  132   b   1  corresponds to at least part of one of the first intervals d 11 . 
         [0024]    In the present embodiment of the invention, the end edge E 11  of each first branch electrode  131   b   1  is located on a first dummy line L 11 , and the end edge E 12  of each second branch electrode  132   b   1  is located on a second dummy line L 12 . The first dummy line L 11  is substantially parallel to the second dummy line L 12 . Let the length of one first interval d 11  and one first branch electrode  131   b   1  being on the first dummy line L 11  be a unit length U 1 , and the length of one second interval d 12  and one second branch electrodes  132   b   1  being on the second dummy line L 12  be the unit length U 1 , the first dummy line L 11  and the second dummy line L 12  are, for example, separated apart by a half of the unit length U 1 . That is, if the unit length U 1  is 10 μm, the first dummy line L 11  and the second dummy line L 12  are separated apart by 5 μm. Thus, the end edge E 11  of any of the first branch electrodes  131   b   1  exactly corresponds to one of the second intervals d 12 , and the end edge E 12  of any of the second branch electrodes  132   b   1  exactly corresponds to one of the first intervals d 11 . 
         [0025]    Referring to  FIG. 2C , liquid crystal pointing arrows of the liquid crystal layer  140  in  FIG. 2A  corresponding to a region A 21  in  FIG. 2B  are shown. When pixels are switched between the bright state and the dark state, the fringe field at the junction between the first branch portion  131   b  and the second branch portion  132   b  guides the liquid crystal molecules to tilt to a consistent direction, as indicated in the region A 22 . Thus, fewer nodes are generated at the junction between the first branch portion  131   b  and the second branch portion  132   b,  so that the liquid crystal display panel  100  has fewer occurrences of streaks and brightness drop. According to the simulation results, if the liquid crystal molecules are distributed as indicated by the liquid crystal pointing arrows in  FIG. 1 , then the liquid crystal molecules spend about 130 ms to resume the stable state. For the liquid crystal display panel  100  of the present embodiment of the invention, the occurrence of streaks is reduced, and the time for resuming the stable state after the occurrence of streaks is effectively reduced to 20 ms. 
         [0026]    In the present embodiment of the invention, the sub-electrode structure S 11  and S 12  is, for example, disposed in a pixel. However, anyone who is skilled in the technology of the invention will understand that the sub-electrode structure S 11  and S 12  can also be disposed in two adjacent pixels so as to reduce the occurrence of streaks, increase brightness and shorten the time for resuming the stable state. 
       Second Embodiment 
       [0027]    Referring to  FIG. 3 , an electrode structure  230  according to a second embodiment of the invention is shown. A first branch portion  231   b  of an electrode structure  230  includes several first branch electrodes  231   b   1 . The two adjacent first branch electrodes  231   b   1  are substantially parallel to each other and separated apart by a first interval d 21 . A second branch portion  232   b  of the electrode structure  230  includes several second branch electrodes  232   b   1 . The two adjacent second branch electrodes  232   b   1  are substantially parallel to each other and separated apart by a second interval d 22 . In the present embodiment of the invention, any of the second branch electrodes  232   b   1  corresponds to at least part of one of the first intervals d 21 , and any of the first branch electrodes  231   b   1  corresponds to at least part of one of the second intervals d 22 , so the advantages of the liquid crystal display panel equipped with the electrode structure  230  are similar to that of the liquid crystal display panel  100  of the first embodiment. 
         [0028]    In the present embodiment of the invention, one end of each first branch electrode  231   b   1  is connected to the first stem electrode  231   t,  and the other end of each first branch electrode  231   b   1  has two corners formed by an end edge E 21  and two sides Si 21 . The two corners are, for example, 90°. Furthermore, one end of each second branch electrode  232   b   1  is connected to the second stem electrode  232   t,  and the other end of each second branch electrode  232   b   1  has two corners formed by an end edge E 22  and two sides Si 22 . The two corners are, for example, 90°. 
         [0029]    Thus, the end edge E 21  of any of the first branch electrodes  231   b   1  corresponds to the side Si 22  of one of the second branch electrodes  232   b   1 , and the end edge E 22  of any of the second branch electrodes  232   b   1  corresponds to the side Si 21  of one of the first branch electrodes  231   b   1 . Let the length of one first interval d 21  and a part of one first branch electrode  231   b   1  being on a first dummy line L 21  be a unit length U 2 , and the length of one second interval d 22  and a part of one second branch electrode  232   b   1  being on a second dummy line L 22  be the unit length U 2 , the end edge E 21  of the first branch electrode  231   b   1  and the side Si 22  of the adjacent second branch electrode  232   b   1  are separated apart by a half of the unit length U 2 , and the end edge E 22  of the second branch electrode  232   b   1  and the side Si 21  of the adjacent first branch electrode  231   b   1  are separated apart by a half of the unit length U 2 , for example. That is, if the unit length U 2  is 10 μm, then the end edge E 21  of the first branch electrode  231   b   1  and the side Si 22  of the adjacent second branch electrode  232   b   1  are separated apart by 5 μm, and the end edge E 22  of the second branch electrode  232   b   1  and the side Si 21  of the adjacent first branch electrode  231   b   1  are separated apart by 5 μm. Let the unit length U 2  of the present embodiment of the invention be equal to the unit length U 1  of the first embodiment. The interval de between a line Le 1  formed by several corners of the first branch electrodes  231   b   1  and a line Le 2  formed by several corners of the second branch electrodes  232   b   1  is smaller than the interval between the first branch electrode  131   b   1  and the second branch electrode  132   b   1  of the first embodiment. In other words, as the corners of each first branch electrode  231   b   1  and the corners of each second branch electrode  232   b   1  protrude inwardly, the interval de is reduced, so that the width of the corresponding streak is reduced and the display quality is increased. 
       Third Embodiment 
       [0030]    Referring to  FIG. 4 , an electrode structure  330  according to a third embodiment of the invention is shown. The electrode structure  330  includes a sub-electrode structure S 31  including a first stem electrode  331   t  and a first branch portion  331   b,  and a sub-electrode structure S 32  including a second stem electrode  332   t  and a second branch portion  332   b.  The sub-electrode structures S 31  and S 32  are vertically adjacent to each other. 
         [0031]    Since any of second branch electrodes  332   b   1  of the second branch portion  332   b  corresponds to at least part of one first interval d 31 , and any of first branch electrodes  331   b   1  of the first branch portion  331   b  corresponds to at least part of one second interval d 32 , the liquid crystal display panel equipped with the electrode structure  330  has similar advantages like the liquid crystal display panel  100  of the first embodiment. 
       Fourth Embodiment 
       [0032]    Referring to  FIG. 5 , an electrode structure  430  according to a fourth embodiment of the invention is shown. The electrode structure  430  includes a stem electrode  430   t,  a first branch portion  431   b  and a second branch portion  432   b.  The stem electrode  430   t  is, for example, cross-shaped, and the first branch portion  431   b  and the second branch portion  432   b  are respectively connected to two opposite sides of the stem electrode  430   t.    
         [0033]    Since any of second branch electrodes  432   b   1  of the second branch portion  432   b  corresponds to at least part of one first interval d 41 , and any of first branch electrodes  431   b   1  of the first branch portion  431   b  corresponds to at least part of one second interval d 42 , the liquid crystal display panel equipped with the electrode structure  430  has similar advantages like the liquid crystal display panel  100  of the first embodiment. 
       Fifth Embodiment 
       [0034]    Referring to  FIG. 6 , an electrode structure  530  according to a fifth embodiment of the invention is shown. The electrode structure  530  includes a main electrode  530   m,  a first branch portion  531   b  and a second branch portion  532   b.  The main electrode  530   m  has a first inclined side R 1  and a second inclined side R 2 . The first inclined side R 1  and the second inclined side R 2  form an indent. Each first branch electrode  531   b   1  of the first branch portion  531   b  is connected to the first inclined side R 1  to be located inside the indent. Each second branch electrode  532   b   1  of the second branch portion  532   b  is connected to the second inclined side R 2  to be located inside the indent. 
         [0035]    Since any of the second branch electrodes  532   b   1  corresponds to at least part of one of the first intervals d 51 , and any of the first branch electrodes  531   b   1  corresponds to at least part of one of the second intervals d 52 , the liquid crystal display panel equipped with the electrode structure  530  has similar advantages like the liquid crystal display panel  100  of the first embodiment. 
         [0036]    According to the liquid crystal display panel and the liquid crystal display device using the same disclosed in the above embodiments of the invention, through the disposition of the first branch portion and the second branch portion adjacent to each other, the occurrence of nodes at the junction between the first branch portion and the second branch portion can be reduced so as to increase the overall display brightness. Moreover, since the time for resuming the stable state after the occurrence of streaks is shortened, the display quality can be further improved. 
         [0037]    While the invention has been described by way of example and in terms of the preferred embodiment(s), it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.