Patent Publication Number: US-2006001823-A1

Title: ODF cell structure

Description:
RELATED APPLICATIONS  
      The present application is based on, and claims priority from, Taiwan Application Serial Number 93119919, filed on Jul. 1, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety.  
     FIELD OF THE INVENTION  
      The present invention relates to a panel structure, and more particularly, to a panel structure for using one drop fill (ODF) technology.  
     BACKGROUND OF THE INVENTION  
      Typical panel packaging comprises three main processes. The first process is a thin film transistor (TFT) array process that is similar to the semiconductor manufacturing process, except that transistors are fabricated on a glass substrate instead of a silicon wafer. The second process is to join the TFT array substrate and a front substrate that is fitted with a color filter. Then, the space between the two substrates is filled with liquid crystal. The third main process is a module assembly process for connecting additional components, such as driver integrated circuits and backlight units, to the fabricated glass panel. Typically, a vacuum filling technology is used to fill the liquid crystal molecules into the space between the color filter and the TFT array substrate. A frame seal  204  with a special opening  206  is arranged around the display region  202  in the TFT array substrate  200  as shown in the  FIG. 1 . This opening  206  is an injection opening for the liquid crystal molecules when the vacuum filling technology is processed.  
       FIG. 2  is a schematic diagram of the vacuum filling technology. When injecting liquid crystal molecules into the space between the two substrates, the panel  208  that finishes the joining of the TFT array substrate and the color filter substrate is firstly placed into a box  210  that is under vacuum. A base  212  is used to fix the panel  208 . A container  214  filled with liquid crystal molecules is placed under the panel  208  for providing liquid crystal molecules to the panel  208 . Since the box  210  is under vacuum, the liquid crystal molecules are drawn into the panel  208  through the injection opening  206 .  
      However, mass production is not feasible because using the vacuum filling technology to fill liquid crystal molecules is too slow. Therefore, another filling technology, one drop fill (ODF) technology, has been developed to resolve the foregoing problem. The ODF process is undergone after the frame seal is finished. The liquid crystal molecules are filled in the region surrounded by the frame seal. Then, the TFT array substrate and the front substrate that is fitted with a color filter are aligned to each other. After alignment of the two substrates, a UV light is used to heat the frame seal to join the two substrates.  
       FIG. 3A  is a top view of a panel that uses an ODF technology to fill liquid crystal molecules.  FIG. 3B  is a cross-sectional view from the AA′ line of the  FIG. 3A . Typically, a black matrix (BM)  302  is built around a display region  306  over the color filter substrate  300  to avoid light leaking from the backlight to influence the display region  306  over the TFT array substrate  312 . Additionally, a fixed width is required to form the black matrix  302  so as to block the light leaking from the non-display region. Therefore, partial overlapping between the black matrix  302  and the shell  308  is necessary. However, the black matrix  302  does not overlap the frame seal  304  so as to keep the black matrix from blocking the UV light when heating the frame seal  304 . These design requirements limit the possibility of further reducing the panel size. Therefore, engineers are pursuing how to reduce the panel size without increasing light leakage.  
     SUMMARY OF THE INVENTION  
      The main purpose of the present invention is to provide a panel structure to reduce the volume of the panel and light leakage.  
      Another purpose of the present invention is to provide a panel structure that can accommodate the ODF technology to fill liquid crystal molecules.  
      Yet another purpose of the present invention is to provide a panel structure with low light leakage whose black matrix extending from the display region is reduced so as to reduce the area of the panel.  
      According to the above purposes of the present invention, any metal layer that is used to fabricate the thin film transistor is formed around the display region of the TFT array substrate so as to avoid the light from the backlight module being scattered out from the non-display region. A black color anti-reflection layer, such as a black color resin, is formed over the metal layer to avoid reflecting environmental light. All masking layers and anti-reflection layers are formed in the TFT array substrate so as to reduce the size of the color filter substrate. Therefore, the whole area of the panel can be reduced.  
      An additional masking layer is formed over the surface and around the display region of the TFT array substrate facing the backlight module. This masking layer is used to block the light passing through the non-display region as leaked light to avoid influencing the display of the panel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      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:  
       FIG. 1  is a schematic top view of a conventional panel that uses a vacuum filling technology to fill liquid crystal molecules;  
       FIG. 2  is a schematic diagram of a machine for processing the vacuum filling technology;  
       FIG. 3A  is a top view of a panel that uses an ODF technology to fill liquid crystal molecules;  
       FIG. 3B  is a cross-sectional view along the AA′ line of  FIG. 3A ;  
       FIG. 4  is a schematic diagram of a panel structure according to the first embodiment of the present invention;  
       FIG. 5  is a schematic diagram of a panel structure according to the second embodiment of the present invention;  
       FIG. 6  is a schematic diagram of a panel structure according to the third embodiment of the present invention;  
       FIG. 7  is a schematic diagram of a panel structure according to the fourth embodiment of the present invention; and  
       FIG. 8  is a schematic diagram of a panel structure according to the fifth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     First Embodiment  
       FIG. 4  is a schematic diagram of a panel structure according to the first embodiment of the present invention. A plurality of color filter films  404  whose color includes red, green and blue are formed over a color filter substrate  400 . It is noticed that only three color filter films are represented in the  FIG. 4 . Black matrices  406  are formed between any two color filter films  404  to separate the color filter films and improve the contrast. A thin film transistor (TFT) array is formed over a substrate  402  to switch the corresponding liquid crystal molecule arrangement to determine whether or not the light can pass through the liquid crystal molecule layer. This thin film transistor array composes the display region of a liquid crystal display. A frame seal  420  is used to join the color filter substrate  400  and the TFT array substrate  402 . A shell  418  is used to package these substrates and expose the display region.  
      Any metal layer  410  that is used to fabricate the thin film transistor array is extended from the display region and formed around the display region of the TFT array substrate  402  so as to keep the light from the backlight module  408  being scattered from the non-display region. The scattered light is the main source of the light leakage. Although the metal layer  410  can block the light from the backlight module  408 , the metal layer  410  reflects the environmental light indicated by the arrow  412 . The reflected environmental light is another source of light leakage. Therefore, a black color anti-reflection layer  414 , such as a black color resin layer, is formed over the metal layer  410  to avoid the reflection of the environmental light. Any anti-reflection material can be used to form the anti-reflection layer  414 . It is noticed that the anti-reflection layer  414  and the black matrix  406  are formed by the same material. Therefore, the anti-reflection layer  414  and the black matrix  406  can be formed together.  
      An additional masking tape  416  can also be formed over the surface of the TFT array substrate  402  facing the backlight module  408  to block the light passing through the non-display region. This masking tape  416  is formed around the TFT array substrate  402 . In other words, an additional masking tape  416  is used in this embodiment to block the light leaking through the non-display region so as to avoid influencing the display of the panel. Other masking material can also be used to replace the masking tape  416 .  
      Therefore, in this embodiment, a masking layer composed of a metal layer  410  and an anti-reflection layer  414 , such as a black color resin layer, is formed over the TFT array substrate  402  to avoid light leakage. Additionally, a masking tape  416  is also formed over the surface of the TFT array substrate  402  facing the backlight module  408  to improve the capacity to avoid light leakage. All masking layers and masking tape are formed in the TFT array substrate  402  in the present invention. Therefore, it is not necessary to manage building the masking layer during fabricating the color filter substrate, hence can reducing the size of the panel.  
     Second Embodiment  
       FIG. 5  is a schematic diagram of a panel structure according to the second embodiment of the present invention. A plurality of color filter films  404  whose color includes red, green and blue is formed over a color filter substrate  400 . It is noticed that only three color filter films are represented in the  FIG. 5 . A thin film transistor (TFT) array is formed over a substrate  402  to switch the corresponding liquid crystal molecule arrangement to determine whether or not the light can pass through the liquid crystal molecule layer. This thin film transistor array composes the display region of a liquid crystal display. On the TFT array substrate  402 , black matrices  406  are formed in the corresponding positions between any two color filter films  404 . The main function of the black matrices  406  is to separate the color filter films  404  and improve the contrast. A frame seal  420  is used to join the color filter substrate  400  and the TFT array substrate  402 . A shell  418  is used to package these substrates and expose the display region. According to the second embodiment, the black matrices  406  are formed on the TFT array substrate  402 , which can simplify the manufacturing process of the color filter substrate  400 .  
      Any metal layer  410  that is used to fabricate the thin film transistor array is extended from the display region and formed around the display region of the TFT array substrate  402  so as to avoid light from the backlight module  408  being scattered from the non-display region. The scattered light is the main source of the light leakage. Although the metal layer  410  can block the light from the backlight module  408 , the metal layer  410  reflects the environmental light indicated by the arrow  412 . The reflected environmental light is another source of light leakage. Therefore, a black color anti-reflection layer  414 , such as a black color resin layer, is formed over the metal layer  410  to avoid the reflection of the environmental light. Any anti-reflection material can be used to form the anti-reflection layer  414 . It is noticed that the anti-reflection layer  414  and the black matrix  406  are formed by the same material. Therefore, the anti-reflection layer  414  and the black matrix  406  can be formed together.  
      An additional masking tape  416  can also be formed over the surface of the TFT array substrate  402  facing the backlight module  408  to block the light passing through the non-display region. This masking tape  416  is formed around the TFT array substrate  402 . In other words, an additional masking tape  416  is used in this embodiment to block the light leaking through the non-display region so as to avoid influencing the display of the panel. Other masking material can also be used to replace the masking tape  416 .  
      Therefore, in this embodiment, a masking layer composed of a metal layer  410  and an anti-reflection layer  414 , such as a black color resin layer, is formed over the TFT array substrate  402  to avoid light leakage. Additionally, a masking tape  416  is also formed over the surface of the TFT array substrate  402  facing the backlight module  408  to improve the capacity to avoid light leakage. All masking layers and masking tape are formed in the TFT array substrate  402  in the present invention. Therefore, it is not necessary to manage building the masking layer during fabricating the color filter substrate, thus reducing the size of the panel.  
     Third Embodiment  
       FIG. 6  is a schematic diagram of a panel structure according to the third embodiment of the present invention. A plurality of color filter films (not shown in this figure) whose color includes red, green and blue is formed over a color filter substrate  400 . A thin film transistor (TFT) array is formed over a substrate  402  to switch the corresponding liquid crystal molecule arrangement to determine whether or not the light can pass through the liquid crystal molecule layer. This thin film transistor array composes the display region of a liquid crystal display. On the TFT array substrate  402 , black matrices  406  are formed in the corresponding positions between any two color filter films. The main function of the black matrices  406  is to separate the color filter films and improve the contrast. Additionally, the black matrices  406  can serve as spacers between the TFT array substrate  402  and the color filter substrate  400 . A frame seal  420  is used to join the color filter substrate  400  and the TFT array substrate  402 . A shell  418  is used to package these substrates and expose the display region.  
      Any metal layer  410  that is used to fabricate the thin film transistor array is extended from the display region and formed around the display region of the TFT array substrate  402  so as to avoid the light from the backlight module  408  being scattered from the non-display region. The scattered light is the main source of light leakage. Although the metal layer  410  can block the light from the backlight module  408 , the metal layer  410  reflects the environmental light indicated by the arrow  412 . The reflected environmental light is another source of light leakage. Therefore, a black color anti-reflection layer  422 , such as a black color resin layer, is formed over the metal layer  410  to avoid the reflection of the environmental light. Moreover, this black color anti-reflection layer  422  can also be formed independently of the metal layer  410 . This black color anti-reflection layer  422  can serve as a spacer according to the embodiment. Any anti-reflection material can be used to form the anti-reflection layer  422 . The anti-reflection layer  422  and the black matrix  406  are formed by the same material. Therefore, the anti-reflection layer  422  and the black matrix  406  can be formed together. Both of them can serve as spacers between the TFT array substrate  402  and the color filter substrate  400 .  
      An additional masking tape  416  can also be formed over the surface of the TFT array substrate  402  facing the backlight module  408  to block the light leaking through the non-display region. This masking tape  416  is formed around the TFT array substrate  402 . In other words, an additional masking tape  416  is used in this embodiment to block the light leaking through the non-display region so as to avoid influencing the display of the panel. Other masking material can also be used to replace the masking tape  416 .  
      Similarly, in this embodiment, a masking layer that is composed of a metal layer  410  and an anti-reflection layer  422 , such as a black color resin layer, is formed over the TFT array substrate  402  to avoid light leakage. Additionally, a masking tape  422  is also formed over the surface of the TFT array substrate  402  facing the backlight module  408  to improve the capacity to avoid light leakage. All masking layers and masking tape are formed in the TFT array substrate  402  in the present invention. Therefore, it is not necessary to manage building the masking layer during fabricating the color filter substrate, hence reducing the size of the panel.  
     Fourth Embodiment  
       FIG. 7  is a schematic diagram of a panel structure according to the fourth embodiment of the present invention. A plurality of color filter films (not shown in this figure) whose color includes red, green and blue are formed over a color filter substrate  400 . A thin film transistor (TFT) array is formed over a substrate  402  to switch the corresponding liquid crystal molecule arrangement to determine whether or not the light can pass through the liquid crystal molecule layer. This thin film transistor array composes the display region of a liquid crystal display. Black matrices  406  are formed between the color resins  426  over the color filter substrate  400  and the layer  428  over the TFT array substrate  402 , wherein the layer  428  is the metal layer, the insulation layer or the amorphous silicon layer of the TFT array. The main function of the black matrices  406  is to separate the color filter films and improve the contrast. Additionally, the black matrices  406  can serve as spacers between the TFT array substrate  402  and the color filter substrate  400 . A frame seal  420  is used to join the color filter substrate  400  and the TFT array substrate  402 . A shell  418  is used to package these substrates and expose the display region.  
      Any metal layer  410  that is used to fabricate the thin film transistor array is extended from the display region and formed around the display region of the TFT array substrate  402  so as to avoid the light from the backlight module  408  being scattered from the non-display region. The scattered light is the main source of light leakage. Although the metal layer  410  can block the light from the backlight module  408 , the metal layer  410  reflects the environmental light indicated by the arrow  412 . The reflected environmental light is another source of light leakage. Therefore, a black color anti-reflection layer  424 , such as a black color resin layer, is formed over or independent of the metal layer  410  to avoid the reflection of the environmental light. The position of the black color anti-reflection layer  424  is related to the thickness of the black color anti-reflection layer  424 . Any anti-reflection material can be used to form the anti-reflection layer  424 . The anti-reflection layer  424  and the black matrix  406  are formed by the same material. Therefore, the anti-reflection layer  424  and the black matrix  406  can be formed together.  
      The main difference between the fourth and third embodiments is the height between the anti-reflection layer  424  and the black matrix  406 . The main purpose of the height difference is to control the cell gap during joining the color filter substrate  400  and the TFT array substrate  402 . The height difference can serve as a buffer when applying pressure to the two substrates for joining. In other words, if there is no height difference, it is easy to break the substrate because of the arrangement density difference between the anti-reflection layer  424  and the black matrix  406 .  
      An additional masking tape  416  can also be formed over the surface of the TFT array substrate  402  facing the backlight module  408  to block the light passing through the non-display region. This masking tape  416  is formed around the TFT array substrate  402 . In other words, an additional masking tape  416  is used in this embodiment to block the light leaking through the non-display region in order to avoid influencing the display of the panel. Other masking material can also be used to replace the masking tape  416 .  
      Similarly, in this embodiment, a masking layer that is composed of a metal layer  410  and an anti-reflection layer  422 , such as a black color resin layer, is formed over the TFT array substrate  402  to avoid light leakage. Additionally, a masking tape  422  is also formed over the surface of the TFT array substrate  402  facing the backlight module  408  to improve the capacity to avoid light leakage. All masking layers and masking tape are formed in the TFT array substrate  402  in the present invention. Therefore, it is not necessary to manage building the masking layer during fabricating the color filter substrate, hence reducing the size of the panel.  
     Fifth Embodiment  
       FIG. 8  is a schematic diagram of a panel structure according to the fifth embodiment of the present invention. A plurality of color filter films (not shown in this figure) whose color includes red, green and blue is formed over a color filter substrate  400 . A thin film transistor (TFT) array is formed over a substrate  402  to switch the corresponding liquid crystal molecule arrangement to determine whether or not the light can pass through the liquid crystal molecule layer. This thin film transistor array composes the display region of a liquid crystal display. Black matrices  406  are formed between the color resins  426  over the color filter substrate  400  and the layer  428  over the TFT array substrate  402 , wherein the layer  428  is the metal layer, the insulation layer or the amorphous silicon layer of the TFT array. The main function of the black matrices  406  is to separate the color filter films and improve the contrast. Additionally, the black matrices  406  can serve as spacers between the TFT array substrate  402  and the color filter substrate  400 . A frame seal  420  is used to join the color filter substrate  400  and the TFT array substrate  402 . A shell  418  is used to package these substrates and expose the display region.  
      Any metal layer  410  that is used to fabricate the thin film transistor array is extended from the display region and formed around the display region of the TFT array substrate  402  so as to avoid the light from the backlight module  408  being scattered from the non-display region. The scattered light is the main source of light leakage. Although the metal layer  410  can block the light from the backlight module  408 , the metal layer  410  reflects the environmental light indicated by the arrow  412 . The reflected environmental light is another source of light leakage. Therefore, a black color anti-reflection layer  432 , such as a black color resin layer, is formed over or independent of the metal layer  410  to avoid the reflection of the environmental light. The position of the black color anti-reflection layer  432  is related to the thickness of the black color anti-reflection layer  432 . Any anti-reflection material can be used to form the anti-reflection layer  432 . The anti-reflection layer  432  and the black matrix  406  are formed by the same material. Therefore, the anti-reflection layer  432  and the black matrix  406  can be formed together.  
      The main difference between the fifth and third embodiment is the height between the anti-reflection layer  432  and the black matrix  406 . The main purpose of the height difference is to control the cell gap during joining the color filter substrate  400  and the TFT array substrate  402 . The height difference can serve as a buffer when applying pressure to the two substrates for joining. In other words, if there is no height difference, it is easy to break the substrate because of the arrangement density difference between the anti-reflection layer  432  and the black matrix  406 .  
      Moreover, a metal layer  410  is exposed in the region  430  that is between the anti-reflection layer  432  and display region. The main purpose is to avoid a sharp change in height to influence the rubbing orientation process for the liquid crystal molecules. Since the region  430  is adjacent to the display region, the height change will influence the rubbing orientation process in the region adjacent to the region  430 . Therefore, a anti-reflection layer  432  is not formed in the region  430  according to this embodiment so as to release the change in height in the region  430 . However, an additional masking layer  434  is formed in a corresponding position in the color filter substrate  400  to keep the environmental light from being reflected by the metal layer  410  located in the region  430 . The material for making the color filter films on the color filter substrate  400  can be used to form the masking layer  434 . Therefore, the masking layer  434  and the color filter film can be formed together, which can simplify the whole process.  
      An additional masking tape  416  can also be formed over the surface of the TFT array substrate  402  facing the backlight module  408  to block the light passing through the non-display region. This masking tape  416  is formed around the TFT array substrate  402 . In other words, an additional masking tape  416  is used in this embodiment to block the light leaking through the non-display region so as to avoid influencing the display of the panel. Other masking material can also be used to replace the masking tape  416 .  
      Similarly, in this embodiment, a masking layer that is composed of a metal layer  410  and an anti-reflection layer  422 , such as a black color resin layer, is formed over the TFT array substrate  402  to avoid light leakage. Additionally, a masking tape  422  is also formed over the surface of the TFT array substrate  402  facing the backlight module  408  to improve the capacity to avoid light leakage. All masking layers and masking tape are formed in the TFT array substrate  402  in the present invention. Therefore, it is not necessary to manage building the masking layer during fabricating the color filter substrate, thereby reducing the size of the panel.  
      According to the embodiments described above, the main masking layers and masking tape are formed in the TFT array substrate. Therefore, there are no masking layers or masking tape in the color filter substrate, which can reduce the whole area of the liquid crystal display.  
      As is understood by a person skilled in the art, the foregoing preferred embodiments of the present invention are illustrative of the present invention rather than limiting of the present invention. It is intended that this description cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structure.