Abstract:
The upper polarizer of a flat display device is located on the upper transparent electrode of the touch panel that is combined with the flat display device. Therefore, the flat display device and the touch panel can share a glass or plastic substrate and a flexible printed circuit board substrate on the second electrode layer.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a flat display device with touch panel, more particularly to a liquid crystal display device with touch panel.  
           [0003]    2. Description of the Prior Art  
           [0004]    Liquid crystal display (LCD) device, which is a par flat display device, is a kind of household electric appliance in nowadays daily life, such as television or monitor of a computer, display device on a calculator, display screen of watch or mobile phone, display device of controlling system, or display panel of CD player. We often use a display screen with touch panel in our ordinary life, such as the introductions of famous scenery. Now it has been practically used in the industry that a touch panel is directly adhered on the upper transparent substrate when a flat display device with touch panel is needed. Such as Kaneda has disclosed the structure that a touch panel is directly adhered on the transmissive-type LCD device referred to the U.S. Pat. No. 6,411,344.  
           [0005]    A conventional transmissive-type LCD device  100 , as shown in FIG. 1, has a plane light guide plate  110  that is used to guide light rays from two light sources  112  at the two opposite ends of plane light guide plate  110  to light-emitting surface thereof and to LCD panel. There are many convex/concave dots on the bottom of plane light guide plate  110  in FIG. 1 to reflect light rays to the upper side. Another way for reflecting upward light rays is to utilize a plurality of slanted portions (V-cuts). A reflector  114  below the opposite surface of light-emitting surface of plane light guide plat  110  reflects all refracted downward light rays to the light-emitting surface thereof. A polarizer  116  and a lower substrate  118  are sequentially on the plane light guide plate  110 . The material of conventional lower substrate  118  uses transparent glass, which thin film transistors (TFTs)  120  are directly formed thereon. A passivation layer  122  and transparent electrodes  124  are formed sequentially on the lower substrate  118  to form a lower plate of the LCD panel. Next, a color filter  130  and transparent electrodes  128  are formed sequentially on another transparent glass, which is upper substrate  132  of the LCD panel, to form upper plate of the LCD panel. Then, upper plate and lower plate are sealed with transparent electrodes  124 ,  128  face to face and vacuumed, and liquid crystal  126  is injected into the space between the upper and lower plates to form the LCD panel. Finally, a polarizer  136  is placed on the upper substrate  132  to form a transmissive-type LCD device  100 .  
           [0006]    The touch panel  102  has a lower transparent substrate  140  in FIG. 1, and a lower transparent electrode layer  142  are directly formed on the lower substrate  140 . A upper transparent electrode layer  144  formed on a upper substrate  146  is combined with the lower transparent electrode layer  142  face to face. The method that presses the upper substrate  146  to contact the lower substrate  140  is used to detect the touch position. There is a polarizer  148  on the upper substrate  146 .  
           [0007]    However, Not only the thickness of whole display module are increased when a touch panel is directly adhered on the panel of LCD device, but also the transmission capacity of light rays is decreased. Besides, too many transparent glass substrates will cause the problems that the depth of focus is longer and the weight of display module is heavier.  
         SUMMARY OF THE INVENTION  
         [0008]    In the light of the state of the art described above, it is an object of the present invention to provide a transparent substrate used as the upper substrate of liquid crystal display (LCD) device and the lower substrate of touch panel is immune to the problems of the conventional flat display device with touch panel described above.  
           [0009]    It is also an object of this invention to make the whole display module lighter and thinner.  
           [0010]    It is another object of this invention to provide a flexible printed circuit board shared by LCD device and touch panel while the lower transparent electrode layer of touch panel is directly formed on the upper substrate of LCD device.  
           [0011]    It is a further object of this invention to solve the problems that the depth of focus is too longer and the transmission capacity of the light rays is decreased.  
           [0012]    It is still an object of this invention to decrease the energy loss of light rays that pass through the media of whole display module.  
           [0013]    In view of the above and other objects which will become apparent as the description proceeds, there is provided according to a general aspect of the present invention a flat display device with touch panel which comprises a flat display device having a plane light source and a display panel with a lower substrate and an upper transparent substrate; and a touch panel on said upper transparent substrate including a first transparent electrode layer on said upper transparent substrate; a second transparent electrode layer on said first transparent electrode layer; a transparent plate on said second transparent electrode layer and a polarizer on said transparent plate.  
           [0014]    Base on the idea described above, wherein said flat display device is a liquid crystal display device.  
           [0015]    Base on the aforementioned idea, wherein said polarizer is shared by said liquid crystal display device and said touch panel.  
           [0016]    Base on the idea described above, wherein said plane light source is a back light source.  
           [0017]    Base on the aforementioned idea, wherein a flexible printed circuit board is shared by said liquid crystal display device and said touch panel.  
           [0018]    In view of the above and other objects which will become apparent as the description proceeds, there is provided according to a general aspect of the present invention a liquid crystal display device with touch panel which comprises a LCD device having an upper transparent substrate and a polarizer; and a touch panel between said upper transparent substrate and said polarizer, wherein said upper transparent substrate is a lower electrode layer substrate of said touch panel.  
           [0019]    Base on the idea described above, wherein said polarizer is on said upper transparent substrate of said touch panel.  
           [0020]    Base on the aforementioned idea, wherein said polarizer is shared by said liquid crystal display device and said touch panel.  
           [0021]    Base on the idea described above, wherein said liquid crystal display device comprises a back light source.  
           [0022]    Base on the aforementioned idea, wherein a flexible printed circuit board is shared by said liquid crystal display device and said touch panel.  
           [0023]    In view of the above and other objects which will become apparent as the description proceeds, there is provided according to a general aspect of the present invention a liquid crystal display device with touch panel which comprises a back light guide plate; a first polarizer on said back light guide plate; a first transparent substrate on said first polarizer; a plurality of thin film transistors on said first transparent substrate; a passivation layer on said first transparent substrate to cover said plurality of thin film transistors; a first transparent electrode layer on said passivation layer; a liquid crystal layer on said first transparent electrode layer; a second transparent electrode layer on said liquid crystal layer; a color filter on said second transparent electrode layer; a second transparent substrate on said color filter; a third transparent electrode layer on said second transparent substrate; a fourth transparent electrode layer on said third transparent electrode layer; a third transparent substrate on said fourth transparent electrode layer; and a second polarizer on said third transparent substrate.  
           [0024]    Base on the idea described above, wherein said second polarizer is shared by said liquid crystal display device and said touch panel.  
           [0025]    Base on the aforementioned idea, wherein a flexible printed circuit board is shared by said liquid crystal display device and said touch panel. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0027]    [0027]FIG. 1 illustrates a view of conventional LCD device with touch panel;  
         [0028]    [0028]FIG. 2 illustrates a view of LCD device with touch panel according to the first embodiment of this invention;  
         [0029]    [0029]FIG. 3 illustrates a view of LCD device with touch panel according to the second embodiment of this invention; and  
         [0030]    [0030]FIG. 4 illustrates a view of the flexible printed circuit board is shared by LCD device and touch panel according to the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]    Some sample embodiments of the present invention will now be described in greater detail. Nevertheless, it should be recognized that the present invention can be practiced in a wide range of other embodiments besides those explicitly described, and the scope of the present invention is expressly not limited except as specified in the accompanying claims.  
         [0032]    The first embodiment of this invention is illustrated in the top view of single pixel of FIG. 3 and in the cross-section view of the sub-pixel of FIG. 4. A single pixel  30  of the color LCD comprises three sub-pixels  31 ,  32 ,  33 . The color of each sub-pixel is respectively red, green and blue color. It means if the sub-pixel  31  is the red sub-pixel, the sub-pixel  32  will be the green sub-pixel and the sub-pixel  33  will be the blue sub-pixel. As for the transflective-type LCD, each sub-pixel  31 ,  32 ,  33  can be divided into the transmissive area  312 ,  322 ,  332  and the reflective area  311 ,  321 ,  331 .  
         [0033]    [0033]FIG. 4 illustrates the cross-section view of the sub-pixel  31  comprises the transmissive area  312  and the reflective area  311 . First, TFTs  401  are formed on the transparent substrate  41  and a transparent dielectric layer  402  is formed thereon subsequently. The transparent dielectric layer  402  can be a SiO 2  layer, a Si 3 N 4  layer or a compound layer comprised of the above two materials. Then a color filter  42  having the thickness t 1  is formed on each sub-pixel. The method for forming the color filter  42  is the same with the method of prior art. The color of color filter depends on the color of corresponding sub-pixel. For example, the sub-pixel  31  is red and the part of color filter  42  corresponding to the sub-pixel  31  is red. Equally, the sub-pixel  32  is green and the part of color filter  42  corresponding to the sub-pixel  32  is green. The sub-pixel  33  is blue and the part of color filter  42  corresponding to the sub-pixel  33  is blue. After the formation of the color filter  42 , the transmissive area and the reflective area will be defined. The elevated reflective layer  43  with the bumps is formed at the reflective area. The material of elevated reflective layer  43  can be photopolymer or other opaque dielectric materials of which the thickness is about 1˜3 μm. If photopolymer is used as the material of elevated reflective layer, it can be coated on the whole color filter  42  first and elevated reflective layer can be made by using the lithography and etching processes. After the formation of the patterns of the transmissive area and the reflective area, the transmissive electrode  44  and the reflective electrode  45  should be formed. The transmissive electrode  44  at the transmissive area  312  that comprises ITO (indium tin oxide) or IZO (indium zinc oxide) is coated by using the sputter method and the reflective electrode  45  at the reflective area  311  that comprises Al, Ag or AlNd alloy is coated by using the sputter method. The transmissive electrode  44 , the reflective electrode  45  and TFTs  401  are electrically connected each other.  
         [0034]    Then the color filter  47  having the thickness t 2  is formed on another transparent substrate  46  having many sub-pixels and each sub-pixel comprises the transmissive area and the reflective area. The method for forming the color filter  47  is the same with the method of prior art. The color of color filter depends on the color of corresponding sub-pixel. A common electrode  48  is formed on the color filter  47 . Finally, the two transparent substrates are sealed with the color filters  42 ,  47  face to face and vacuumed, and liquid crystal is injected into the space between the two transparent substrates to form the liquid crystal layer  49 .  
         [0035]    The light rays in the reflective area  311  pass through the color filter  47  twice and the light rays in the transmissive area  312  pass through the color filter  42  and the color filter  47 . Therefore, we can adjust the thickness t 1  of color filter  42  and the thickness t 2  of color filter  47  to generate the similar or same color saturation in the reflective area and the transmissive area while the transflective-type color LCD uses both of the transmissive and reflective display modes at the same time.  
         [0036]    The second embodiment of this invention is illustrated in the top view of single pixel of FIG. 3 and in the cross-section view of the sub-pixel of FIG. 5, which illustrates the cross-section view of the sub-pixel  31  comprises the transmissive area  312  and the reflective area  311 . First, TFTs  501  are formed on the transparent substrate  51  and a transparent dielectric layer  502  is formed thereon subsequently. The transparent dielectric layer  502  can be a SiO 2  layer, a Si 3 N 4  layer or a compound layer comprised of the above two materials. Then a color filter  52  having the thickness t 3  is formed on each sub-pixel. The method for forming the color filter  52  is the same with the method of prior art. The color of color filter depends on the color of corresponding sub-pixel. For example, the sub-pixel  31  is red and the part of color filter  52  corresponding to the sub-pixel  31  is red. Equally, the sub-pixel  52  is green and the part of color filter  52  corresponding to the sub-pixel  32  is green. The sub-pixel  33  is blue and the part of color filter  52  corresponding to the sub-pixel  33  is blue. It is the only difference between this and the first embodiment of FIG. 4 that there is not any the color filter  52  in the reflective area. After the formation of the color filter  52 , the transmissive area and the reflective area will be defined. The elevated reflective layer  53  with the bumps is formed at the reflective area. The material of elevated reflective layer  53  can be photopolymer or other opaque dielectric materials of which the thickness is about 1˜3 μm. If photopolymer is used as the material of elevated reflective layer, it can be coated on the whole color filter  52  first and elevated reflective layer can be made by using the lithography and etching processes. After the formation of the patterns of the transmissive area and the reflective area, the transmissive electrode  54  and the reflective electrode  55  should be formed. The transmissive electrode  54  at the transmissive area  312  that comprises ITO (indium tin oxide) or IZO (indium zinc oxide) is coated by using the sputter method and the reflective electrode  55  at the reflective area  311  that comprises Al, Ag or AlNd alloy is coated by using the sputter method. The transmissive electrode  54 , the reflective electrode  55  and TFTs  501  are electrically connected each other.  
         [0037]    Then the color filter  57  having the thickness t 4  is formed on another transparent substrate  56  having many sub-pixels and each sub-pixel comprises the transmissive area and the reflective area. The method for forming the color filter  57  is the same with the method of prior art. The color of color filter depends on the color of corresponding sub-pixel. A common electrode  58  is formed on the color filter  57 . Finally, the two transparent substrates are sealed with the color filters  52 ,  57  face to face and vacuumed, and liquid crystal is injected into the space between the two transparent substrates to form the liquid crystal layer  59 .  
         [0038]    The light rays in the reflective area  311  pass through the color filter  57  twice and the light rays in the transmissive area  312  pass through the color filter  52  and the color filter  57 . Therefore, we can adjust the thickness t 3  of color filter  52  and the thickness t 4  of color filter  57  to generate the similar or same color saturation in the reflective area and the transmissive area while the transflective-type color LCD uses both of the transmissive and reflective display modes at the same time.  
         [0039]    Although the specific embodiment has been illustrated and described, it will be obvious to those skilled in the art that various modifications may be made without departing from what is intended to be limited solely by the appended claims.