Patent Publication Number: US-2009225266-A1

Title: Multi-domain vertical alignment thin film transistor liquid crystal display

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of and claims the priority benefit of an application Ser. No. 11/548,973, filed on Oct. 12, 2006, which is a divisional of an application Ser. No. 10/708,297, filed on Feb. 23, 2004. The application Ser. No. 10/708,297 claims the priority benefit of Taiwan application serial no. 92120001, filed on Oct. 29, 2003. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a multi-domain vertical alignment thin film transistor liquid crystal display, and more particularly to a multi-domain vertical alignment thin film transistor liquid crystal display adapted to resolve issues of color shift and color washing out resulting from change of view angle. 
     2. Description of the Related Art 
     Because of the shrinkage of semiconductor device and displays, portable devices are more available to people. As to displays, cathode ray tubes (CRT) have dominated the market as their high quality and economy. However, because of space restriction, power consumption and concern of environmental protection, CRT still have some issues needed to be resolved. Therefore, because of its high quality, space utility, low power consumption and non-radiation, thin film transistor liquid crystal display (TFT LCD) has gradually replaced CRT. 
     To date, the liquid crystal displays with high contrast ratio, no gray scale inversion, little color shift, high luminance, full color, high brightness, high responsive speed and wide view angle are required. In order to achieve the purpose of wide view angle, some displays, such as TN complying with wide viewing film display, in-plane switching display (IPS), fringe field switching display and multi-domain vertical alignment display (MAV), are developed to perform the purpose. Following are the descriptions of the prior art multi-domain vertical alignment thin film transistor liquid crystal display. 
       FIG. 1  is a schematic cross-sectional view showing a prior art multi-domain vertical alignment thin film transistor liquid crystal display. Referring to  FIG. 1 , the multi-domain vertical alignment thin film transistor liquid crystal display comprises a multi-domain vertical alignment thin film transistor liquid crystal display panel  116 , a first wide viewing film  108 , a first polarizer film  110 , a second wide viewing film  112  and a second polarizer film  114 . The first wide viewing film  108  is on a first surface  116   a  of the thin film transistor liquid crystal display panel  116 . The first polarizer film  110  is on the first viewing film  108 . The second wide viewing film  112  is on a second surface  116   b  of the thin film transistor liquid crystal display panel  116 . The second polarizer film  114  is on the second wide viewing film  112 . The multi-domain vertical alignment thin film transistor liquid crystal display panel  116  comprises a color filter substrate  102 , a thin film transistor array substrate  100 , a liquid crystal layer  104  and protrusions  106 , wherein the protrusions  106  are used to arrange the directions of the liquid crystal molecules. Moreover, the protrusions  106  can be disposed on the color filter substrate  102  or the thin film transistor array substrate  100 , or on both of them. 
     As to the prior art multi-domain vertical alignment thin film transistor liquid crystal display, the transmittance-level curve varies with the change of view angle. In other word, the change of view angle will result in color shift and color washing out. If these issues can be resolved, the multi-domain vertical alignment thin film transistor liquid crystal display will be more competitive. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the present invention is to provide a multi-domain vertical alignment thin film transistor liquid crystal display (MVA TFT-LCD) for resolving the issues of color shift and color washing out resulting from the change of the viewing angle. 
     The present invention discloses a multi-domain vertical alignment thin film transistor liquid crystal display, which comprises a multi-domain vertical alignment thin film transistor liquid crystal display panel, a first wide viewing film, a first polarizer film, a second wide viewing film and a second polarizer film. The first wide viewing film is on a first surface of the thin film transistor liquid crystal display panel. The first polarizer film is on the first viewing film, wherein a surface of the first polarize film has a diffusive pattern. Additionally, the second wide viewing film is on a second surface of the thin film transistor liquid crystal display panel. The second polarizer film is on the second wide viewing film. 
     The present invention discloses another multi-domain vertical alignment thin film transistor liquid crystal display, which comprises a thin film transistor array substrate, a color filter substrate, a liquid crystal layer, a first wide viewing film, a first polarizer, a second wide viewing film and a second polarizer. The color filter substrate is over the thin film transistor array substrate, wherein the color filter substrate has diffusive particles. Additionally, the liquid crystal layer is between the thin film transistor array substrate and the color filter substrate. The first wide viewing film is on a surface of the color filter substrate. The first polarizer is on the first wide viewing film. The second wide viewing film is on a surface of the thin film transistor array substrate. The second polarizer is on the second wide viewing film. 
     The present invention discloses a method of fabricating a polarizer film applied to a multi-domain vertical alignment thin film transistor liquid crystal display. First, the method provides a substrate and forms an optical thin film thereon. Then, a diffusive pattern is formed on a surface of the optical thin film for forming a polarizer film having a diffusive pattern. The method of forming the diffusive pattern on the surface of the optical thin film comprises, for example, photolithographic and etching technologies for forming the diffusive pattern on the surface of the optical thin film, or the formation of a diffusive film on the surface of the optical thin film. 
     The present invention discloses a method of fabricating a color filter substrate applied to a multi-domain vertical alignment thin film transistor liquid crystal display. First, the method provides a substrate and forms a black matrix and a color photoresist layer thereon, wherein the color photoresist layer has diffusive particles. The method of forming the color photoresist layer having the diffusive particles comprises, for example, spreading the diffusive particles within the color photoresist layer or forming a diffusive film thereon. 
     Because the multi-domain vertical alignment thin film transistor liquid crystal display of the present invention uses the polarizer film having the diffusive pattern or particles or the color filter substrate having the diffusive particles, light from the display has a specific diffusive angle for modifying the transmittance-level curve corresponding to different view angles. Therefore, the distribution of transmittance-level curve corresponding to different view angles is corrected and the issues of color shift and color washing out resulting from the change of the viewing angle are reduced. 
     In order to make the aforementioned and other objects, features and advantages of the present invention understandable, a preferred embodiment accompanied with figures is described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view showing a prior art multi-domain vertical alignment thin film transistor liquid crystal display. 
         FIG. 2  is a schematic cross-sectional view showing a preferred multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. 
         FIG. 3A  is a schematic cross-sectional view showing a preferred polarizer film applied to a multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. 
         FIG. 3B  is a schematic cross-sectional view showing another preferred polarizer film applied to a multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. 
         FIG. 4  is a schematic cross-sectional view showing another preferred multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. 
         FIG. 5A  is a schematic cross-sectional view showing a preferred color filter substrate applied to a multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. 
         FIG. 5B  is a schematic cross-sectional view showing another preferred color filter substrate applied to a multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. 
     
    
    
     DESCRIPTION OF SOME EMBODIMENTS 
       FIG. 2  is a schematic cross-sectional view showing a preferred multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. Referring to  FIG. 2 , the multi-domain vertical alignment thin film transistor liquid crystal display comprises a multi-domain vertical alignment thin film transistor liquid crystal display panel  216 , a first wide viewing film  208 , a first polarizer film  210   a , a second wide viewing film  212  and a second polarizer film  210   b . The multi-domain vertical alignment thin film transistor liquid crystal display panel  216  comprises a color filter substrate  202   a , a thin film transistor array substrate  200 , a liquid crystal layer  204  and protrusions  206 , wherein the protrusions  206  are used to arrange the directions of the liquid crystal molecules. 
     The first wide viewing film  208  is on a first surface  216   a  of the thin film transistor liquid crystal display panel  216 . The first polarizer film  210   a  is on the first viewing film  208 . The second wide viewing film  212  is on a second surface  216   b  of the thin film transistor liquid crystal display panel  216 . The second polarizer film  214  is on the second wide viewing film  212 . Generally, the polarizer film includes an iodine type polarizer and dye type polarizer, wherein the polarizer film applied to active array LCD is an iodine type polarizer. 
     In the embodiment, the method of reducing color shift resulting from the change of view angles comprises forming a diffusive pattern on the surface of the first polarizer film  210   a  for forming a polarizer film having a diffusive structure. In another embodiment, a diffusive film is formed on the first polarizer film  210   a . Both of them can make the first polarizer film have diffusive characteristic. Following are the detail descriptions for these two methods. 
       FIG. 3A  is a schematic cross-sectional view showing a preferred polarizer film applied to a multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. Referring to  FIG. 3A , a substrate  300  is provided and an optical thin film  302  is formed thereon. Then, a diffusive pattern  302   a  is formed on the optical thin film  302 . The method of forming the diffusive pattern  302   a  on the surface of the optical thin film  302  comprises, for example, photolithographic and etching technologies for patterning the surface of the optical thin film  302 . The polarizer film  210   a  formed therefrom is composed of the substrate  300 , the optical thin film  302  and the diffusive pattern  302   a , wherein the optical thin film  302  is on the substrate  300 . The diffusive pattern is on the optical thin film  302 . The other surface of the substrate  300  is attached to the first wide viewing film  208 . 
       FIG. 3B  is a schematic cross-sectional view showing another preferred polarizer film applied to a multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. Referring to  FIG. 3B , a substrate  300  is provided and an optical thin film  302  is formed thereon. Then, a diffusive film  304  is formed on the optical thin film  302 , wherein the diffusive film  304  is composed of, for example, a transparent film and diffusive particles  304   a  spared therein. The polarizer film formed therefrom is composed of the substrate  300 , the optical thin film  302  and the diffusive film  304 , wherein the optical thin film  302  is on the substrate  300 . Additionally, the diffusive film  304  is on the optical thin film  302  and has diffusive particles  304   a  therein. 
     In addition to resolving the issues of color shift and color washing out resulting from the change of the viewing angle by the polarizer film and the diffusive pattern, the present invention can also uses a color filter substrate having the diffusive pattern to resolve the issues mentioned above. Following is the detail description. 
       FIG. 4  is a schematic cross-sectional view showing another preferred multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. Referring to  FIG. 4 , the liquid crystal display comprises a thin film transistor array substrate  200 , a color filter substrate  202   b , a liquid crystal layer  204 , a first wide viewing film  208 , a first polarizer  210   b , a second wide viewing film  212  and a second polarizer  214 . The color filter substrate  202   b  is over the thin film transistor array substrate  200 , wherein the color filter substrate  202   b  has diffusive particles. Additionally, the liquid crystal layer  204  is between the thin film transistor array substrate  200  and the color filter substrate  202   b . The first wide viewing film  208  is on a surface of the color filter substrate  202   b . The first polarizer  210   b  is on the first wide viewing film  208 . The second wide viewing film  212  is on a surface of the thin film transistor array substrate  200 . The second polarizer  214  is on the second wide viewing film  212 . 
     It should be noted that the method of fabricating the color filter substrate  202   b  having the diffusive particles can comprise, for example, spreading the diffusive particles (not shown) in a color photoresist layer (not shown) of the color filter substrate  202   b , or forming a diffusive film (not shown) on a color photoresist layer (not shown) of the color filter substrate  202   b . Following are the detail descriptions of these two methods. 
       FIG. 5A  is a schematic cross-sectional view showing a preferred color filter substrate applied to a multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. Referring to  FIG. 5A , a substrate  400  is provided and a black matrix  402  is formed thereon. If the material of the black matrix  402  is opaque resin, it can be formed by photolithographic processes; if the material of the black matrix  402  is Cr, it can be formed by photolithographic and etching processes. In addition, the substrate  400  can be glass, plastic or transparent material. A color photoresist layer  404  is then formed on the substrate  400  covering a portion of the black matrix  402 , wherein the color photoresist layer  404  is composed of pluralities of red-color photoresist blocks (not shown), green-color photoresist blocks (not shown) and blue-color photoresist blocks (not shown). The color photoresist layer  404  has diffusive particles  404   a  therein. The method of forming the color photoresist layer  404  on the substrate  400  can comprise, for example, performing a spin-coating process and a baking process for forming a red-color photoresist layer (not shown), wherein the red-color photoresist layer has diffusive particles spared therein. Then a lithographic process is performed for reserving a specific area of red-color photoresist layer (not shown). The processes described above are repeated for forming specific areas of green-color photoresist layer and blue-color photoresist layer (not shown). The color filter substrate formed thereform comprises the substrate  400 , the black matrix  402  and the color photoresist layer  404 , wherein the black matrix  402  is on the substrate  400 . Additionally, the color photoresist layer  404  is on the substrate  400  covering a portion of the black matrix  402 , wherein the color photoresist layer  404  has diffusive particles  404   a  spared therein. 
       FIG. 5B  is a schematic cross-sectional view showing another preferred color filter substrate applied to a multi-domain vertical alignment thin film transistor liquid crystal display of the present invention. Referring to  FIG. 5B , a substrate  400  is provided and a black matrix  402  is formed thereon. A color photoresist layer  406  is then formed on the substrate  400  covering a portion of the black matrix  402 . Finally, a diffusive film  408  is formed on the color photoresist layer  406 , wherein the diffusive film  408  is composed of, for example, a transparent film and diffusive particles  408   a  spared therein. The color filter substrate formed thereform comprises the substrate  400 , the black matrix  402 , the color photoresist layer  406  and the diffusive film  408 . The black matrix  402  is on the substrate  400 . The color photoresist layer  406  is on the substrate  400  covering a portion of the black matrix  402 . Additionally, the diffusive film  408  is on the color photoresist layer  406  and the black matrix  402 . The color filter substrate described above can further comprise an electrode film, a planarization film, an optical film, etc. 
     Because the multi-domain vertical alignment thin film transistor liquid crystal display of the present invention uses the polarizer film having the diffusive pattern or particles or the color filter substrate having the diffusive particles, light from the display has a specific diffusive angle for modifying the transmittance-level curve corresponding to different view angles. Therefore, the distribution of transmittance-level curve corresponding to different view angles is corrected and the issues of color shift and color washing out resulting from the change of the viewing angle are reduced. Accordingly, the multi-domain vertical alignment thin film transistor liquid crystal display of the present invention has following advantages: 
     1. The present invention can reduce the issues of color shift and color washing out resulting from the change of the viewing angle without changing pixel structures; and 
     2. The present invention can reduce the issues of color shift and color washing out resulting from the change of the viewing angle without changing the relationship between the transparency and gray level. 
     Although the present invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be constructed broadly to include other variants and embodiments of the invention which may be made by those skilled in the field of this art without departing from the scope and range of equivalents of the invention.