Abstract:
A bank structure for a display panel is provided. The display panel comprises a substrate, and the bank structure is formed on the surface of the substrate. The bank structure comprises a periphery and a partition, wherein the periphery forms a receiving space with the substrate and the partition is disposed in the receiving space for separating the receiving space into two sub-spaces with fluid-communication. Therefore, the ink can be injected and uniformly distributed in the sub-spaces to overcome the disadvantages of poor injection precision and increasing the spray control of the ink.

Description:
[0001]    This application claims the benefit from the priority of Taiwan Patent Application No. 096136762, filed on Oct. 1, 2007, the contents of which are herein incorporated by reference in their entirety. 
       CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to a bank structure for a display panel. More particularly, the present invention relates to a bank structure capable of improving ink distribution for a display panel. 
         [0005]    2. Descriptions of the Related Art 
         [0006]    Conventionally, a widely adopted method for manufacturing a large color filter is the pigment dispersed method. According to this method, a black photo-resist containing carbon is applied onto a glass substrate using a photo process, and then subjected to a series of processes such as soft baking, exposure, development and hard baking, thereby, forming a black matrix on the substrate as a bank structure to shield light. When used in a color filter, the bank structure functions to shield light leaked due to the disorderly arrangement of the liquid crystal molecules in inactive regions. Generally, the regions that are shielded by the bank structure comprise lines, transistors and common electrodes on the substrate, among which the main light leakage occurs at the edge of the transistor lines. Therefore, the bank structure at such locations must have a larger width than the transistor lines. Because the bank structure helps to enhance the contrast of the liquid crystal display (LCD), it has been widely applied in current LCD products. 
         [0007]    Subsequent to the formation of the black matrix, the ink containing a pigment is applied using a similar photo process to yield the color filters of various colors. However, as the substrates become increasingly larger in size, the technologies of producing color filters by ink injection have also been developed. The ink injecting method is characterized by a large spray-coating area, a simple manufacturing process and a reduced material cost. In addition to being used for producing red, green and blue (R, G, and B) color filters, the method may also be used to form spacer balls and polyimide (PI). 
         [0008]    In producing a color filter by ink injection, a bank is first formed on the surface of a glass substrate, and then ink is injected by a precision ink injection apparatus into the receiving space formed by the bank. Unfortunately, when the ink is dropped into the receiving space formed by the bank, a small volume of the receiving space or discontinuous and asymmetric areas of the receiving space that are divided by common electrodes or other electrodes often lead to poor injection precision and poor injection dose accuracy. This tends to cause underfilling or an ink drop to protrude in the center portion thereof, thereby making the edges or corners of the receiving space devoid of ink. Also possibly, the incorrect injecting locations or ununiform injection dose may even cause ink to overflow and mix with the ink of other colors in the adjacent pixels, thus resulting in a decreased yield. 
         [0009]    It follows from the above description that because of the poor ink injection precision and poor injection dose accuracy in producing color filters by ink injection, there is still no bank structure that can prevent these problems. Accordingly, it is still highly desirable in the art to provide a bank structure complying with both the requirements described above. 
       SUMMARY OF THE INVENTION 
       [0010]    One objective of this invention is to provide a bank structure for a display panel, wherein the display panel comprises a substrate. The bank structure is formed on the surface of the substrate. The bank structure comprises a periphery and a partition. The periphery and the substrate both form a receiving space, into which the partition divides the receiving space into a first sub-space and a second sub-space in fluid communication with each other. When dropped into the receiving space, ink will fill into the first sub-space and the second sub-space. In this way, ink will be distributed uniformly in the receiving space, thus improving the ink injection precision and injection dose accuracy and prevent ink overflow and consequent color mixtures with the adjacent pixels. Furthermore, the extension of the receiving space may also mitigate the central protrusion of an ink drop in a limited space due to the surface tension and cohesion. 
         [0011]    To this end, the periphery has a first vertical dimension, and the partition has a second vertical dimension smaller than the first vertical dimension. As a result, a fluid communication is established between the first sub-space and the second sub-space, so that when the ink is dropped therein, the ink will be allowed to flow between the two sub-spaces over the partition. 
         [0012]    Another objective of this invention is to provide a method of manufacturing a bank structure for a display panel, in which a bank is formed with different vertical dimensions by a patterning process to obtain the aforesaid bank structure. 
         [0013]    Yet a further objective of this invention is to provide a method of manufacturing a bank structure for a display panel, in which the smaller vertical dimension is formed at the borders where the peripheries of the adjacent receiving spaces of the same color adjoin with each other, to establish a fluid communication between the different receiving spaces of the same color. 
         [0014]    The detailed technology and preferred embodiments implemented for the subject invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1   a  illustrates a bank structure of this invention; 
           [0016]      FIG. 1   b  is a cross-sectional view taken along line A-A′ in  FIG. 1   a;    
           [0017]      FIG. 1   c  is a cross-sectional view taken along line B-B′ in  FIG. 1   a;    
           [0018]      FIGS. 2   a  to  2   c  are schematic views of a manufacturing method of this invention; 
           [0019]      FIG. 3   a  illustrates another embodiment of this invention; 
           [0020]      FIG. 3   b  is a schematic cross-sectional view taken along line C-C′ in  FIG. 3   a;    
           [0021]      FIG. 4   a  is a schematic view of yet a further embodiment of this embodiment; and 
           [0022]      FIG. 4   b  is a schematic cross-sectional view taken along line D-D′ in  FIG. 4   a.    
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    The following embodiments and attached drawings are intended to illustrate rather than to limit this invention. It should be noted that the elements unrelated to this invention have been omitted from depiction in the following embodiments and attached drawings. 
         [0024]      FIG. 1   a  illustrates a bank structure  11  of this invention when applied in a display panel, while  FIG. 1   b  and  FIG. 1   c  illustrate a cross-sectional view of a portion of the bank structure  11  respectively. More specifically,  FIG. 1   b  is a cross-sectional view taken along line A-A′ in  FIG. 1   a , while  FIG. 1   b  is a cross-sectional view taken along line B-B′ in  FIG. 1   a.    
         [0025]    The bank structure  11  depicted in  FIG. 1   a  is formed on a substrate  10 , and comprises a periphery  101  and a partition  102 . The periphery  101  forms a receiving space  12 , into which the partition  102  is disposed. In  FIG. 1   a , identical depictions represent identical structures. In other words,  FIG. 1   a  depicts a plurality of receiving spaces, each of which has a similar structure to that of the receiving space  12 . 
         [0026]    In reference to both  FIGS. 1   b  and  1   c , the periphery  101  has a first vertical dimension H 1 , and the partition  102  has a second vertical dimension H 2  smaller than the first vertical dimension H 1 . Consequently, the periphery  101  can define a receiving space  12  for receiving ink. The receiving space  12  uses the periphery  101  as a peripheral wall thereof and has a first vertical dimension H 1 . The partition  102  is disposed in the receiving space  12  and is connected integrally with the periphery  101  to divide the receiving space  12  into a first sub-space  121  and a second sub-space  122 . Because the partition  102  has a vertical dimension H 2  smaller than H 1 , a fluid communication crossing over the partition  102  is established between the first sub-space  121  and the second sub-space  122 . That is, when dropped into the receiving space  12 , ink may fill into both the first sub-space  121  and the second sub-space  12 . As a result, the ink will be distributed uniformly in the receiving space  12  to result in a better ink injection precision and injection dose accuracy. The receiving space  12  corresponds to one of the pixel structures in the display panel, while the partition  102  corresponds to one of the common electrodes (not shown) of this pixel structure to shield the common electrode from leaking light. 
         [0027]      FIGS. 2   a  to  2   c  depict a flow diagram of the process for manufacturing the bank structure  11  in  FIG. 1   a , in which a halftone mask process is used as an example. Initially, as shown in  FIG. 2   a , a material layer  22  is formed across the substrate  21  of a display panel. The material layer  22  may be formed from an opaque and photosensitive organic material, for example, a deep colored photosensitive resin to adapt to a subsequent halftone mask process.  FIG. 2   b  depicts an exposure process used on the material  22  through a halftone mask  23 . In this embodiment, the material layer  22  is formed from deep colored photosensitive resin of negative photo-resistive nature. The halftone mask  23  may include full-exposure areas  231 , half-exposure areas  232  and non-exposure areas  233 . Portions of the material layer  22  corresponding to the full-exposure areas  231  are cured subsequently to an exposure process; portions of the material layer  22  corresponding to the half-exposure areas  232  are half cured subsequently to the exposure process and are partially removed in a subsequent development process; and portions of the material layer  22  corresponding to the non-exposure areas  233  remain unchanged without subsequent curing and are removed completely in the subsequent development process. The patterned material layer  22  resulted from the exposure process is illustrated in  FIG. 2   c . At this point, the patterned material layer  22  forms the bank structure  11  comprising a periphery  101  and a partition  102  as depicted in  FIG. 1C . In the invention, the material layer  22  could also be formed from deep colored photosensitive resin of positive photo-resist which takes a mask with reversed full-exposure and non-exposure area. 
         [0028]      FIG. 3   a  illustrates a schematic view of another bank structure  31  of this invention, and  FIG. 3   b  is a cross-sectional view of a portion of the bank structure  31  taken along line C-C′ in  FIG. 3   a . The bank structure  31  is formed on a substrate  30 , and comprises a periphery  301  and a partition  302 . Unlike the bank structure shown in  FIG. 1   a , the periphery  301  has a portion  3031  formed with a third vertical dimension H 3  smaller than the first vertical dimension H 1 , as shown in  FIG. 3   b . Consequently, a fluid communication may be established between the receiving space  32  and another receiving space  33 . That is, ink dropped into the receiving space  32  will also fill in the receiving space  33 . Conceivably, in this embodiment, the fluid communication design will only apply to the receiving spaces that will be filled with ink of the same color. 
         [0029]      FIG. 4   a  illustrates a bank structure  41  in accordance with another embodiment of this invention, while  FIG. 4   b  is a cross-sectional view of a portion of the bank structure  41  taken along line D-D′ in  FIG. 4   a . The bank structure  41  is formed on a substrate  40 , and comprises a first periphery  401 , a plurality of partitions  402  and a second periphery  403 . The first periphery  401  has a first vertical dimension H 1  and defines a first receiving space  42 . The second periphery  403 , which also has the first vertical dimension H 1 , adjoins the first periphery  401  and defines a second receiving space  43 . On the other hand, the partition  402  has a second vertical dimension H 2  smaller than the first vertical dimension H 1 . Unlike what is shown in  FIG. 1   a  and  FIG. 3   a , a portion of the bank structure  404  where the periphery  401  of the first receiving space  42  adjoins the periphery  403  of the second receiving space  43  is formed with the second vertical dimension H 2 , so that the ink dropped into these receiving spaces will flow over the partitions  42 . Similarly, the first receiving space  42  and the second receiving space  43  shall be filled with ink of the same color. 
         [0030]    It should be noted that the bank structures shown in  FIG. 3   a  and  FIG. 4   a  can both be formed by the manufacturing process illustrated in  FIG. 2   a  to  FIG. 2C . Furthermore, all the above bank structures may also be formed by other appropriate mask processes, for example, a gray-scale mask process, a spacer mask process, or a dual-mask process with different exposing energy. These mask processes are characterized in that subsequent to the development process, a bank with different vertical dimensions will be formed, thus obtaining a bank structure of this invention. Such a process may be readily substituted by those of ordinary skill in the art, and is not just limited thereto. 
         [0031]    The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in this field may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.