Patent Publication Number: US-2006017868-A1

Title: Apparatus of liquid crystal display for compensating chromaticity of reflected light and the method of fabrication

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates generally to a liquid crystal display (LCD), and more particularly to an apparatus of a liquid crystal panel for compensating chromaticity of the reflected light and the method of fabrication.  
      2. Description of the Related Art  
      As shown in  FIG. 1 , a conventional color liquid crystal panel has an upper glass substrate  1  and a lower glass substrate  2  between which a liquid crystal layer  3 , a protective layer  4 , a filter layer  5  and reflective layer  6  are mounted. The reflective layer  6  has a plurality of total-reflection regions  6   a  and apertures  6   b . A backlight module  7  is mounted behind the lower glass substrate  2  to complete a transflecitve liquid crystal display. The panel can be respectively provided with a polarizing plate (not shown) on opposite sides thereof for various requirements.  
      While the transflective liquid crystal display shows an image under a reflective mode, lights will travel through the filter layer  5  twice. The conventional filter layer  5  is made of a color resin material with a lower color intensity to reduce the light resistance thereof and increase the penetrability thereof. But such filter layer provides a poor color intensity. On the contrary, the filter layer  5  can be made of a color resin material with a high color intensity, but the higher light resistance makes it having a poor illumination. Same situation happens to the light provided from the backlight module  7  traveling through the filter layer  5  once.  
      To fix the drawback, a six-color method is invited to fabricate a liquid crystal penal. As shown in  FIG. 2 , the penal has an upper glass substrate  1  and a lower glass substrate  2  between which a liquid crystal layer  3 , a protective layer  4 , a filter layer  8  and reflective layer  6  are mounted. The filter layer  8  has a first filter film  8   a , which is made of a color resin material with a lower color intensity and is provided on total-reflection regions  6   a  of the reflective layer  6  for reflection, and a second filter film  8   b , which is made of a color resin material with a lower color intensity and is provided in apertures  6   b  of the reflective layer  6  for passing light. The first and the second filter film  8   a  and  8   b  has different light resistances to make the panel having a well light penetrability while it shows an image under a light reflection condition and has a well color intensity while it shows an image under a light penetration condition.  
      However, the first and the second filter film  8   a  and  8   b  is arranged in parallel and alternate so that the widths thereof are only half of the original design. It also has drawbacks of hard to align because of the narrow widths thereof and a thickness of the first filter film  8   a  is restricted to keep the filter layer  8  having a flat surface. These drawbacks make the penal having a greater defective in fabrication and hard for mass production.  
     SUMMARY OF THE INVENTION  
      The primary objective of the present invention is to provide an apparatus and a method, which the filter layer has two stacked color filter films to make them easy to align and to reduce the defective of fabrication.  
      The secondary objective of the present invention is to provide an apparatus and a method, which the filter layer is capable of increasing the color intensity and luminance.  
      According to the objectives of the present invention, a liquid crystal penal has a lower color filter film, a reflective film, an upper color filter film, a lower transparent electrode and an upper glass substrate with an upper transparent electrode on a bottom thereof stacked on the on a lower glass substrate in sequence, and then a liquid crystal layer is provided in between the upper and the lower transparent electrode. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a sectional view of a conventional liquid crystal penal;  
       FIG. 2  is a sectional view of another conventional liquid crystal penal;  
       FIG. 3  is a flow chart of the method of a first preferred embodiment of the present invention;  
       FIG. 4A  to  FIG. 4L  are sectional views of the first preferred embodiment of the present invention, showing the steps of fabrication;  
       FIG. 5  is a sectional view of the first preferred embodiment of the present invention, showing the light paths;  
       FIG. 6A  to  FIG. 6L  are sectional views of a second preferred embodiment of the present invention, showing the steps of fabrication;  
       FIG. 7  is a sectional view of the second preferred embodiment of the present invention, showing the light paths;  
       FIG. 8  is a sectional view of the penal of the present invention, which there is no protective layer provided and the reflective layer has the apertures;  
       FIG. 9  is a sectional view of another penal of the present invention, which there is no protective layer provided and the reflective layer is total covered, and  
       FIG. 10  is a sectional view of a third preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      As shown in  FIG. 3  and  FIG. 4 , a method of making a liquid crystal panel  10 , which is capable of compensating the chromaticity of the reflected light, comprises the steps: 
          a) Provide a lower glass substrate  12 , as shown in  FIG. 4A .     b) Provide a lower color filter film  14 :        

      As shown in  FIGS. 4B, 4C  and  4 D, the photolithography method and curing are applied to provide red-light sensitive members  141 , green-light sensitive members  142  and blue-light sensitive members  143  on the lower glass substrate  12  to form the lower color filter film  14 . The lower color filter film  14  has a thickness between 300 nm and 3000 nm. The sensitive members are made of color resin materials with high color intensity. 
          c) Provide a reflective film  16  on the lower color filter film  14 :        

      As shown in  FIG. 4E , the reflective film  16  is made of a film with gold, silver, copper, aluminum, palladium or the alloy or is made of a multi-layer film of nonmetallic materials. The reflective film  16  is made from the photolithography method and has a thickness between 10 nm and 1000 nm. The reflective film  16  has a plurality of total-reflection regions  161  and apertures  162 . The reflective film  16  has an aperture ratio between 5% and 80%. 
          d) Provide an upper color filter film  18  on the reflective film  16 :        

      As shown in  FIGS. 4F, 4G  and  4 H, the photolithography method is applied again to provide red-light sensitive members  181 , green-light sensitive members  182  and blue-light sensitive members  183  on the reflective film  16  to form the upper color filter film  18 . The upper color filter film  18  has a thickness between 300 nm and 3000 nm. The sensitive members  181 ,  182  and  183  are made of color resin materials with color intensities less than the color intensities of the sensitive members  141 ,  142  and  143  of the lower color filter film  14 . The upper and the lower filter films  14  and  18  complete a color filter layer  20 . 
          e) Provide a protective layer  22  on the upper color filter film  18 :        

      As shown in  FIG. 41 , a resin material is coated on the upper color filter film  18  to form the protective layer  22  with a flat surface. 
          f) Provide a lower transparent electrode  24  on the surface of the protective layer  22 , as shown in  FIG. 4J .     g) Provide an upper glass substrate  26  with an upper transparent electrode  28  on a bottom side thereof on the lower transparent electrode  24 , as shown in  FIG. 4K .     h) Provide a liquid crystal layer  30 :        

      As shown in  FIG. 4L , a liquid crystal is provide to where between the upper transparent electrode  28  and the lower transparent electrode  24  to form the liquid crystal layer  30 . A phase difference And of the liquid crystal layer  30  is in a range between 100 nm and 900 nm. For a STN-LCD, the phase difference And is preferred in a range between 700 nm and 900 nm.  
      After these steps, the liquid crystal penal  10  of the first preferred embodiment of the present invention is shown in  FIG. 5 . In the penal  10 , the filter layer  20  is consisted of the upper and the lower color filter films  18  and  14  stacked and the upper and the lower color filter films  18  and  14  is made of the materials with different color intensities. The red-light sensitive member  181  of the upper color filter film  18  aligns the red-light sensitive member  141  of the lower color filter film  14 . Same as the green-light and blue-light sensitive members  182  and  183  of the upper  18 , they align the green-light and blue-light sensitive members  142  and  143  of the lower color filter film  14 . In practice, the penal  10  is provided with a backlight module behind the lower glass substrate  12 . The penal  10  is laminated with two polarizing plates (not shown) on the upper and the lower glass substrates  26  and  12  respectively to meet various requirements.  
      As shown in  FIG. 5 , in the light reflection mode, a light in front of the upper glass substrate  26  traveling through the upper glass substrate  26  is reflected by the total-reflection regions  161  after it travels through the upper color filter film  18  and the reflected light travels through the upper color filter film  18  again. Because the upper color filter film  18  is made of the color resin material with lower color intensity, the reflected light has a well luminance. In the light penetration mode, a light provided from the backlight module  32  travels through the lower color filter film  14  and the apertures  162  of the reflective film  16 , and then traveling out of the penal  10 . Because the lower color filter film  14  is made of the color resin material with higher color intensity and the red-light, the green-light and the blue-light sensitive members  181 ,  182  and  183  of the upper color filter film  18  align the red-light, the green-light and the blue-light sensitive members  141 ,  142  and  143  of the lower color filter film  14  respectively, the light still has a well color intensity even through the light has to travel through the upper color filter film  18 .  
      If the penal  10  of the present invention is installed in the STN-LCD, the display provides a higher color intensity and a greater luminance under the interaction of the light reflection mode and the light penetration mode.  
      The advantages of the penal  10  of the present invention are:  
      1. The red-light, the green-light and the blue-light sensitive members  181 ,  182  and  183  of the upper color filter film  18  align the red-light, the green-light and the blue-light sensitive members  141 ,  142  and  143  of the lower color filter film  14  respectively. It fixes the drawback of the conventional color filter layer made from the six-color method, which the parallel filter films are hard to be aligned. The method of present invention, therefore, reduces the defective of fabrication.  
      2. The color filter layer  20  of the present invention has a flat surface and the sensitive members of the color filter films  14  and  18  are arranged in order, so that the penal  10  made of the method of the present invention provides a higher color intensity and a greater luminance.  
      3. The thickness of the upper color filter film  18  of the filter layer  20  is designated to increase the light reflection.  
       FIG. 6  and  FIG. 7  show a penal  40  of the second preferred embodiment of the present invention.  FIG. 6A  to  FIG. 6L  show the steps of a method making the penal  40 , which is similar to the method of the first preferred embodiment as described above, except that, in  FIG. 6E , a reflective film  42  with a thickness between 5 nm and 200 nm is totally covered on a top side of the lower color filter film  14 . The reflective film  42  serves both functions of passing light through and reflecting light.  FIG. 7  shows the penal  40  works under both of the light reflection mode and the light penetration mode, and it still provides a higher color intensity and a greater luminance as the penal  10  of the first preferred embodiment does.  
      In addition, in the process of making the penal of the present invention, the penal is provided with or without the protective layer for various products, such as TN type LCD. As shown in  FIG. 7 , a penal  50  is provided with an upper glass substrate  51 , an upper transparent electrode  52 , a liquid crystal layer  53 , a lower transparent electrode  54 , an upper color filter film  55 , a reflective layer  56  with a plurality of total-reflection regions  561  and apertures  562 , a lower color filter film  57  and a lower glass substrate  58  in sequence, but no protective layer.  FIG. 9  shows another penal  60 , which is similar to the penal  50 , except that a reflective layer  62  is provided to serve both function of passing light through and reflecting light.  
      The present invention is applied to TFT-LCD too. As shown in  FIG. 10 , a TFT liquid crystal penal  70  has an upper substrate  71 , an upper transparent electrode  72 , a liquid crystal layer  73 , a lower transparent electrode  74 , an upper color filter film  75 , a reflective layer  76 , a lower color filter film  77 , thin film transistors  78 , a lower substrate  79  and conductive portions  80 . The penal  70  still provides a higher color intensity and a greater luminance. The phase different And of the liquid crystal layer  73  is preferred in a range between 100 nm and 400 nm.