Abstract:
An LCD panel and method for forming the same are proposed. The LCD panel includes a TFT substrate, an opposite substrate, and a liquid crystal LC layer sandwiched between the TFT substrate and the opposite substrate. The opposite substrate includes main spacers for sparing space between the TFT substrate and the opposite substrate and secondary spacers. The TFT substrate includes TFTs and color filters with recesses. The secondary spacers fit the recesses, and the secondary spacers do not touch the TFT substrate. Not only a thickness of the LCD panel is adjustable when the liquid crystal is injected between the TFT substrate and the opposite substrate, but also the optical characteristics of the LCD panel can not change to effect display quality when the LCD panel is squeezed by force.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a liquid crystal display (LCD) panel and a method of forming the same, and more particularly, to an LCD panel comprising a plurality of mixed hybrid spacers and a method of forming the same. 
         [0003]    2. Description of the Prior Art 
         [0004]    Nowadays, light and thin flat display panels are widely used in current consumer electronic products. Liquid crystal displays (LCDs) which are colorful monitors with high resolution are widely used in various electronic products such as monitors for mobile phones, personal digital assistants (PDAs), digital cameras, laptop computers, and notebook computers. 
         [0005]    A conventional LCD is formed by a color filter substrate, a thin film transistor array substrate, and a liquid crystal layer therebetween. Such LCD has less resolution, a lower aperture ratio, and a defect of misalignment between the color filter substrate and the thin film transistor array substrate. 
         [0006]    Referring to  FIG. 1 ,  FIG. 1  is a diagram showing the structure of a traditional LCD panel  10  comprising a color filter on array (COA) substrate  12 . The LCD panel  10  comprises the COA substrate  12  comprising a color filter  16  and a thin-film transistor (TFT)  14 , an opposite substrate  18 , a spacer  20 , and an LC layer  22 . The spacer  20  and the LC layer  22  are placed between the COA substrate  12  and the opposite substrate  18 . The spacer  20  is used for sparing space between the COA substrate  12  and the opposite substrate  18 . The color filter  16  is fabricated from at least one red color filter, one green color filter, and one blue color filter. The color filter  16  is directly formed on the TFT  14  so there are no alignment errors. Moreover, the capacitor between the COA substrate  12  and the opposite substrate  18  is small so a pixel electrode  24  can be extended outwards to increase the aperture ratio of the pixel. 
         [0007]    However, the thickness of the color filter  16  is 3 um, causing the COA substrate  12  comprising the color filter  16  and the TFT  14  to be flattened. As a result, the spacer  20  on the opposite substrate  18  touches the color filter  16 , making it difficult to control the thickness of the LC layer  22 . 
       SUMMARY OF THE INVENTION 
       [0008]    Therefore, an object of the present invention is to provide an LCD panel of controlling the thickness of the LC layer and a method of manufacturing the same for solving the problem occurring in the conventional technology. Because the thickness of the LC layer is controlled, the optical characteristics of the LCD panel do not change, which allows the LCD panel to show images normally. 
         [0009]    According to the present invention, a liquid crystal display (LCD) panel, comprising a thin-film transistor (TFT) substrate, an opposite substrate, and a liquid crystal (LC) layer, the 
         [0010]    LC layer disposed in the gap between the TFT substrate and the opposite substrate, the opposite substrate comprising a plurality of main spacers and a plurality of secondary spacers, the plurality of main spacers used for sparing space between the TFT substrate and the opposite substrate. The TFT substrate comprises a plurality of TFTs, a plurality of color filters, disposed on the plurality of TFTs and comprising a plurality of recesses, and a plurality of pixel electrodes covering the plurality of color filters. Each of the plurality of pixel electrodes is electrically connected to the corresponding TFT. The plurality of secondary spacers fit the plurality of recesses, and the plurality of recesses do not touch the TFT substrate. 
         [0011]    In one aspect of the present invention, the LCD panel further comprises a black matrix, and the plurality of main spacers and the plurality of secondary spacers are disposed on the black matrix. 
         [0012]    In another aspect of the present invention, the TFT substrate comprises: a glass substrate, a plurality of scan lines, and a plurality of data lines. The plurality of scan lines and the plurality of data lines are disposed on the glass substrate. Each of the plurality of scan lines and each of the plurality of data lines are electrically connected to the corresponding TFT. The TFT substrate further comprises a passivation layer between the plurality of TFTs and the plurality of color filters. 
         [0013]    In another aspect of the present invention, the pixel electrode comprises a a transparent electrode, a reflective electrode or a transflective electrode. 
         [0014]    In another aspect of the present invention, each color filter is a red color filter, a green color filter, or a blue color filter. 
         [0015]    According to the present invention, a method of manufacturing an LCD panel comprises 
         [0016]    providing a glass substrate; forming a TFT, a common electrode, a scan line, and a data line on the glass substrate; forming a passivation layer on the TFT; forming a color filter on the passivation layer; etching the color filter for forming a recess; forming a pixel electrode on the color filter and on the recess; forming an LC layer on the pixel electrode; covering an opposite substrate on the LC layer, the opposite substrate comprising a main spacer and a secondary spacer, the main spacer used for sparing space between the TFT substrate and the opposite substrate, the secondary spacer fitting the recess, and the secondary spacer not touching the TFT substrate. 
         [0017]    In one aspect of the present invention, the steps of forming a TFT, a common electrode, a scan line, and a data line on the glass substrate comprise: forming a first metallic layer on the glass substrate; etching the first metallic layer for forming a gate of the TFT, the common electrode, and the scan line; forming an insulating layer on the gate of the TFT, the common electrode, and the scan line; forming a passage of the TFT on the insulating layer; and forming and etching a second metallic layer for forming a source and a drain of the TFT and the data line. 
         [0018]    In one aspect of the present invention, before the step of forming a pixel electrode on the color filter and the recess, the method further comprises: etching the color filter and the passivation layer for forming a first via on the drain of the TFT and a second via on the common electrode. 
         [0019]    In one aspect of the present invention, the method of forming the main spacer and the secondary spacer comprises a photo etching process (PEP) and an inkjet printing process. 
         [0020]    In contrast to prior art, the LCD panel of the present invention comprising a plurality of mixed hybrid spacers has a better structural strength. The plurality of main spacers are used for sparing space between the COA substrate and the opposite substrate. The plurality of secondary spacers are used for sparing space between the COA substrate and the opposite substrate whenever the LCD panel is squeezed by force. In this way, the optical characteristics of the LCD panel will not change because of variations in the distance of the LC layer. Thus, the LCD panel can show images normally. In addition, the elasticity of the LC layer is increased when the LC layer is injected into the space between the opposite substrate and the COA substrate because a distance still exists between the plurality of secondary spacers and the COA substrate. 
         [0021]    These and other features, aspects and advantages of the present disclosure will become understood with reference to the following description, appended claims and accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a diagram showing the structure of a traditional LCD panel comprising a color filter on array (COA) substrate. 
           [0023]      FIG. 2  is a schematic diagram showing an LCD panel according to an embodiment of the present invention. 
           [0024]      FIG. 3  is a schematic diagram showing the structure of the LCD panel. 
           [0025]      FIGS. 4 and 5  show schematic diagrams of the opposite substrate as shown in  FIG. 3 . 
           [0026]      FIGS. 6 and 11  show schematic diagrams of the COA substrate as shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, electronic equipment manufacturers may refer to a component by different names. This documents does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ” Also, the term “electrically connect” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. 
         [0028]    Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. 
         [0029]    Referring to  FIG. 2 ,  FIG. 2  is a schematic diagram showing an LCD panel  100  according to an embodiment of the present invention. The LCD panel  100  comprises a glass substrate  210 , a plurality of scan lines  212 , a plurality of data lines  214 , a plurality of TFTs  220 , a plurality of common electrodes  280 , and a plurality of pixel electrodes  240 . The plurality of scan lines  212 , the plurality of data lines  214 , and the plurality of TFTs  220  are disposed on the glass substrate  210 . The plurality of scan lines  212  are arranged with the plurality of data lines  214  alternatively, which forms a plurality of pixels arranged complying with a matrix. Each of the plurality of TFTs  220  is electrically connected to a pixel electrode  240 , a scan line  212 , and a data line  214 . 
         [0030]    Referring to  FIG. 2  and  FIG. 3 ,  FIG. 3  is a schematic diagram showing the structure of the LCD panel  100 . The LCD panel  100  further comprises a COA substrate  200 , an opposite substrate  300 , and an LC layer  400  between the COA substrate  200  and the opposite substrate  300 . The COA substrate  200  further comprises a glass substrate  210  and a plurality of pixel electrodes  240 . Each of the plurality of TFTs  220  comprises a gate  221 , a source  222 , a drain  223 , and a semiconductor layer  224 . The gate  221  is electrically to a scan line  212 ; the source  222  is electrically connected to a data line  214 ; the drain  223  is electrically connected to the pixel electrode  240 . The semiconductor layer  224  comprises an a-Si layer  224   a  used as a passage of the TFT  220  and an ohmic contact layer  224   b  used for reducing resistance. When the gate  221  of the TFT  220  receives a scan signal transmitted through the scan line  212 , the TFT  220  is turned on. A data signal transmitted through the data line  214  is sent to the pixel electrode  240  through the source  222  and the drain  223 . The alignment of LC molecules in the LC layer  400  (not shown) is controlled depending on the voltage difference between voltage applied to the data signal and common voltage applied to the common electrode  280 . Images having different grayscales are shown on the pixel elextrode  240 . A color filter  260  is formed on a passivation layer  270  covering the TFT  220 . The color filter  260  in each of the plurality of pixels is fabricated from at least one red color filter, one green color filter, and one blue color filter. The color filter  260  covers the TFT  220 . A plurality of recesses  233  are randomly disposed on the color filter  260 . Moreover, a first via  231  is formed on the drain  223  of the TFT  220 , and a second via  232  is formed on the common electrode  280 . The pixel electrode  240  is positioned on the color filter  260 . In this way, the pixel electrode  240  is also electrically connected to the drain  223  of the TFT  220 . A storage capacitor is formed in the overlapping area formed by the common electrode  280  and the pixel electrode  240 . The capacitance of the storage capacitor is in inverse proportion to the distance between the common electrode  280  and the pixel electrode  240  and is affected by a dielectric constant of a media between the common electrode  280  and the pixel electrode  240 . That&#39;s why the second via  232  is formed. The formation of the second via  232 , on one hand, is used for shortening the distance between the common electrode  280  and the pixel electrode  240 , and on the other hand, is used for reducing the influence of the dielectric constant of the color filter  260  on the capacitance of the storage capacitor. 
         [0031]    The pixel electrode  240 , such as a transparent electrode, is disposed on the color filter  260  and electrically connected to the corresponding TFT  220 . The pixel electrode  240  can also be a reflective electrode or a transflective electrode in other preferred embodiments of the present invention. 
         [0032]    The opposite substrate  300  comprises a substrate  310 , a black matrix  320 , a plurality of main spacers  360 , and a plurality of secondary spacers  370 . The plurality of main spacers  360  and the plurality of secondary spacers  370  are disposed on the black matrix  320 . The black matrix  320  can be optionally formed on the TFT  220 , the scan line  212 , and on the data line  214  to minimize light leakage from the surroundings of the pixel. 
         [0033]    The plurality of main spacers  360  are used for sparing space between the COA substrate  200  and the opposite substrate  300 . The distribution of the plurality of main spacers  360  on the opposite substrate  300  is determined depending upon practical demands. For example, each of the plurality of pixels is equipped with a main spacer  360 , or every few pixels are equipped with a main spacer  360 . In addition, the plurality of secondary spacers  370  are placed besides the plurality of main spacers  360 . The plurality of secondary spacers  370  are arbitrarily arranged in areas except areas where the base  330  of each of the plurality of main spacers  360  is located. Or, the plurality of secondary spacers  370  are disposed near the plurality of main spacers  360 . Or, the plurality of secondary spacers  370  replace some of the plurality of main spacers  360  and are arranged alternatively with the plurality of main spacers  360 . The plurality of secondary spacers  370  are used for sparing space between the COA substrate  200  and the opposite substrate  300  whenever the LCD panel  100  is squeezed by force. The LCD panel  100  comprising the plurality of main spacers and the plurality of secondary spacers forms the LCD panel  100  comprising a plurality of mixed hybrid spacers. The plurality of mixed hybrid spacers are used for enhancing the pressure resistance of the 
         [0034]    LCD panel  100  and the stability in the assembly process, increasing the elasticity of the LC layer  400  when the LC layer  400  is injected into the space between the COA substrate  200  and the opposite substrate  300 . Preferably, the plurality of secondary spacers  370  fit the plurality of recesses  233  while the plurality of secondary spacers  370  do not touch the COA substrate  200 . In other words, a distance still exists between the plurality of secondary spacers  370  and the COA substrate  200 . 
         [0035]    Referring to  FIGS. 4 to 11 ,  FIGS. 4 to 11  are schematic diagrams showing the LCD panel  100  of the present invention.  FIGS. 4 and 5  show schematic diagrams of the opposite substrate  300  as shown in  FIG. 3 .  FIGS. 6 and 11  show schematic diagrams of the COA substrate  200  as shown in  FIG. 3 . 
         [0036]    Referring to  FIG. 4 , a substrate  310  is provided. The substrate  310  is a transparent substrate which may be a glass substrate, a plastic substrate, etc. Next, a black matrix  320  is formed on the substrate  310 . The black matrix  320  is made of black resin. 
         [0037]    Referring to  FIG. 5 , a photo etching process (PEP) or an inkjet printing process is performed on the substrate  310  to form the plurality of main spacers  360  and the plurality of secondary spacers  370  on the black matrix  320 . The plurality of secondary spacers  370  are close to the plurality of main spacers  360 . Or, the plurality of secondary spacers  370  replace some of the plurality of main spacers  360  and are arranged with the plurality of main spacers  360  alternatively. So far, the opposite substrate  300  is almost completed. 
         [0038]      FIGS. 6 and 11  are schematic diagrams showing the processes of forming the COA substrate  200  as shown in  FIG. 3 . 
         [0039]    Referring to  FIG. 6 , a glass substrate  210  is provided. A metallic thin-film deposition process is conducted so that a first metallic layer (not shown) is formed on the surface of the glass substrate  210 . Meanwhile, a first PEP is conducted using a first mask to form the gate  221  of the TFT  220  and the common electrode  280 . 
         [0040]    Referring to  FIG. 7 , an insulating layer  230  made of silicon nitride (SiNx) is deposited and covers the gate  221  and the commin electrode  280 . A plurality of amorphous Si (a-Si) layers are successively deposited on the insulating layer  230 . An N+a-Si layer at high dopant doping concentrations is deposited on the insulating layer  230  as well. The semiconductor layer  224  is formed after a second PEP is conducted using a second mask. The semiconductor layer  224  comprises the a-Si layer  224   a  used as a passage of the TFT  220  and the ohmic contact layer  224   b  used for reducing resistance. 
         [0041]    Referring to  FIG. 8 , a second metallic layer (not shown) is formed on the insulating layer  230  and covers the insulating layer  230  completely. Both of the source  222  and the drain  223  of the TFT  220  are defined after a third PEP is conducted using a third mask. The data line  214  is directly connected to the source  222 . 
         [0042]    Referring to  FIG. 9 , the passivation layer  270  made of SiNx is deposited, covering the source  222  and the drain  223 . Afterwards, a fourth PEP is conducted using a fourth mask to remove part of the passivation layer  270  on the drain  223  until the surface of the drain  223  is exposed. The first via  231  is formed on the drain  223 . Also, part of the passivation layer  270  on the common electrode  280  is etched with the fourth PEP until the surface of the insulating layer  230  is exposed. The second via  232  is formed on the common electrode  280 . 
         [0043]    Referring to  FIG. 10 , the color filter  260  is formed on the passivation layer  270 . Afterwards, a fifth PEP is conducted using a fifth mask to etch the color filter  260 . The color filter  260  in each of the plurality of pixels is fabricated from at least one red color filter, one green color filter, and one blue color filter. It is notified that the plurality of recesses  233  can be randomly formed on the color filter  260  using the fifth PEP. 
         [0044]    Referring to  FIG. 11 , a transparent conducting layer made of indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on the color filter  260 . Next, a sixth PEP is conducted using a sixth mask to etch the transparent conducting layer to form the pixel electrode  240 . The pixel electrode  240  is electrically connected to the drain  223  of the TFT  220  through the first via  231  formed beforehand. Besides, the distance between the common electrode  280  and the pixel electrode  240  is the smallest near the second via  232 . Since the common electrode  280  is separated from the pixel electrode  240  by the passivation layer  270  (not including the color filter  260 ), the capacitance of the storage capacitor formed by the common electrode  280  and the pixel electrode  240  is higher. Until now, the COA substrate  200  is almost completed. 
         [0045]    Referring to  FIG. 3 , the opposite substrate  300  is disposed on the COA substrate  200 , and the LC layer  400  is injected into the space between the opposite substrate  300  and the COA substrate  200 . The plurality of secondary spacers  370  fit the plurality of recesses  233 . The plurality of main spacers  360  are used for sparing space between the COA substrate  200  and the opposite substrate  300 . The plurality of secondary spacers  370  are used for sparing space between the COA substrate  200  comprising the color filter and the opposite substrate  300  whenever the LCD panel  100  is squeezed by force. Between the plurality of secondary spacers  370  and the COA substrate  200  still exists a distance. The LCD panel  100  comprising the plurality of main spacers  360  and the plurality of secondary spacers  370  forms the LCD panel  100  comprising a plurality of mixed hybrid spacers. The plurality of mixed hybrid spacers are used for enhancing the pressure resistance of the LCD panel  100  and the stability in the assembly process, increasing the elasticity of the LC layer  400  when the LC layer  400  is injected into the space between the opposite substrate  300  and the COA substrate  200 . 
         [0046]    While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.