Abstract:
A method of fabricating a display panel comprises the steps of: forming a controlling elements array substrate and a flexible color filter, respectively; forming a displaying medium on the controlling elements array substrate; and assembling the flexible color filter to the controlling elements array substrate for disposing it on the displaying medium layer. A method of fabricating a flexible color filter comprises the steps of: forming a flexible substrate on a rigidly substrate; forming a color filter film comprising a plurality of color filter patterns; and separating the flexible substrate from the rigidly substrate. Since the color filter film are formed before separating the flexible substrate from the rigid substrate, the flexible color filter may have good resolution and process yield.

Description:
This application claims priority to a Taiwan application No. 098100781 filed Jan. 9, 2009. 
     BACKGROUND 
     1. Field of the Invention 
     The invention relates to a method of fabricating display panel, and more particularly, to a method of fabricating display panel with flexible color filter. 
     2. Description of the Related Art 
     With progress of the flat display technique, more and more electrical products, especially portable electrical products such as mobile phones, e-books, digital cameras and personal digital assistants etc., are equipped with flat display apparatuses. The development trend of the portable electrical product is to achieve light weight and thin thickness, so the flat display apparatus for the portable electrical product should have these features. 
     It is well known that the flexible panel display not only has features of light weight and thin thickness, but also has features of flexibility and is not easy to be broken. Therefore, the development of the flexible panel display has become increasingly important. During the fabricating process of conventional flexible panel display, a controlling elements array and a color filter film are printed on plastic substrates respectively by roll-to-roll printing process first. Then, the substrates are assembled to each other. 
     However, the yield and the capacity of the roll-to-roll printing process are limited since the steadiness thereof is not good enough. Furthermore, the resolution of the controlling elements or the color filter film formed by the roll-to-roll printing process only achieve to about 30 micrometer. It is not corresponding to the tendency toward request the resolution of the nowadays display panel to 1 micrometer. 
     Besides, since the controlling elements array or the color filter film are printed on the plastic substrates by ink jet printing during the conventional roll-to-roll printing process, the accuracy of process is more difficult to control than the accuracy of the lithographic and etching process. Moreover, the controlling elements array or the color filter film may be not even because the quantity of ink jetted by the clogged jet head is not uniform. 
     BRIEF SUMMARY 
     Therefore, the invention is directed to a method of fabricating flexible color filter for increasing the process yield thereof. 
     The invention is further directed to a method of fabricating of display panel for increasing the accuracy of aligning the flexible color filter and the controlling elements array substrate. Accordingly, the process yield of the display panel may be improved. 
     The invention provides a method of fabricating a flexible color filter. First, a rigid substrate is provided and a flexible substrate is formed on the rigid substrate. Next, a color filter film is formed on the flexible substrate. Then, the flexible substrate is separated from the rigid substrate. 
     The invention also provides a method of fabricating a display panel. First, a flexible color filter is formed by the aforementioned steps and a controlling elements array substrate with a display region and a peripheral circuit region is formed and a display medium is disposed within the display region. Next, the flexible color filter is assembled to above the controlling elements array substrate and on the display medium layer. Then, a driving circuit is disposed on the controlling elements array substrate and located in the peripheral circuit region. 
     According an embodiment of the invention, the step of separating the flexible substrate from the rigid substrate comprises a laser releasing process. 
     According an embodiment of the invention, a light-shielding layer with a plurality of openings is formed before forming the color filter film on the flexible substrate, wherein the color filter patterns are formed in the openings. 
     According an embodiment of the invention, a second rigid substrate is provided before forming the controlling elements array substrate, and then the controlling elements array substrate is formed on the rigid substrate. The controlling elements array substrate is separated from the second rigid substrate by, for example, a laser releasing process after disposing the driving circuit thereon. 
     According an embodiment of the invention, the color filter film may comprise red, green and blue color filter patterns. Moreover, according to another embodiment, the color filter film further comprise white color filter patterns. 
     According an embodiment of the invention, the material of the flexible substrate may be polyimide, polyethylene terephathalate, polyether ether ketone, or polyethylene naphthalene, PMMA, PS, PAR, PC, TAC, ARTON. 
     According an embodiment of the invention, the display medium layer may be an electro-phoretic layer, an electro-wetting layer or a cholesteric liquid crystal layer. 
     In the invention, since the color filter film are formed on the flexible substrate formed on the rigid substrate before separating the flexible substrate from the rigid substrate, the process yield and the capacity of the flexible color filter and the display panel with the same may be improved. 
     In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, preferred embodiments accompanied with figures are described in detail below. It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of this invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which: 
         FIG. 1A  to  FIG. 1C  are schematic cross-section views illustrating the flexible color filter during the fabricating process thereof according to an embodiment of the invention. 
         FIG. 2  is a schematic cross-section view illustrating the color filter film formed on the flexible substrate according to another embodiment of the invention. 
         FIG. 3  is a schematic cross-section view illustrating the light-shielding layer and the color filter film formed on the flexible substrate according to another embodiment of the invention. 
         FIG. 4A  to  FIG. 4E  are schematic cross-section views illustrating a display panel during the fabricating process thereof according to an embodiment of the invention. 
         FIG. 5  is a schematic view illustrating a controlling elements array substrate according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  to  FIG. 1C  are schematic cross-section views illustrating the flexible color filter during the fabricating process thereof according to an embodiment of the invention. Referring to  FIG. 1A , a flexible substrate  120  is formed on a rigid substrate  110 . The material of the rigid substrate  110  is, for example, glass or stainless steel and the material of the flexible substrate  120  may be polyimide, polyethylene terephathalate, polyether ether ketone, polyethylene naphthalene, polymethyl methacrylate, polystyrene, polyarylate, polycarbonate, TAC or ARTON. 
     Referring to  FIG. 1B , a color filter film  130  is formed on the flexible substrate  120 . In this embodiment, the color filter film  130  comprises a plurality of color filter patterns such as red color filter patterns R, green color filter patterns G and blue color filter patterns B. In the other embodiment, the color filter film  130  may also comprise white color filter patterns W for increasing the display brightness, as shown in  FIG. 2 . It should be noted that the color filter film  130  may be formed by lithographic and etching process. Furthermore, the color filter patterns may not only comprise cyan color filter patterns, yellow color filter patterns and magenta color filter patterns, also black color filter patterns. The colors of the color filter patterns of the invention are not limited hereto. 
     Moreover, a light-shielding layer  140  with a plurality of openings  142  may be formed on the flexible substrate  120  for improving the contrast of the display images and preventing the light from mixing before forming the color filter film  130  in another embodiment, as shown in  FIG. 3 . Then, the color filter patterns are formed in the openings  142  and the material of the light-shielding layer  140  is, for example, resin or the other opaque materials. 
     Referring to  FIG. 1C , the flexible substrate  120  is separated from the rigid substrate  110  to form a flexible color filter  100 . For example, the flexible substrate  120  is separated from the rigid substrate  110  by the laser releasing process. 
     Since the flexible substrate  120  is separated from the rigid substrate  110  after forming the color filter film  130  on the flexible substrate  120  by lithographic and etching process, the yield and capacity of the flexible color display medium module  100  may be improved substantially. The application of the flexible color filter  100  would be described in the follow-up paragraphs, but the invention is not limited hereto. 
       FIG. 4A  to  FIG. 4E  are schematic cross-section views illustrating a display panel during the fabricating process thereof according to an embodiment of the invention. Referring to  FIG. 4A , a controlling elements array substrate  210  with a display region  210   a  and a peripheral circuit region  210   b  is formed first. In detail, the controlling elements array substrate  210  comprises a substrate  212  and a plurality of pixel units  214  formed thereon. The places where the pixel units  214  disposed is determined as the display region  210   a  of the controlling elements array substrate  210 . 
     It is worth to say that the controlling elements array substrate  210  of this embodiment may be flexible. During the process of fabricating the flexible controlling elements array substrate  210 , the substrate  212  with flexibility is formed on a rigid substrate  201  first. The material of the substrate  212  is similar to or the same with the material of the aforementioned flexible substrate  120 , it is unnecessary to say herein. Then, the pixel units  214  are formed on the substrate  212 . That is, the controlling elements array substrate  210  is formed on the rigid substrate  201  first in the invention. 
       FIG. 5  is a schematic view illustrating a controlling elements array substrate according to an embodiment of the invention. Referring to  FIG. 5 , each pixel unit  214  comprises a scan line  215 , a data line  216 , a thin film transistor  217  and a pixel electrode  218 . The thin film transistor  217  is electrically connected to the corresponding scan line  215  and the corresponding data line  216 , each pixel electrode  218  is electrically connected to the data line  216  through the thin film transistor  217 . That is, a thin film transistor array is used as controlling elements in this embodiment. 
     It should be noted that although the active controlling elements are used in this embodiment, the invention is not limited hereto. Those skilled in the art should know that the display panel of the invention also can be controlled by passive controlling elements array. 
     Referring to  FIG. 4B , a display medium layer  220  is formed on the controlling elements array. In detail, the display medium layer  220  is disposed on the pixel units  214  located in the display region  210   a  of the controlling elements array substrate  210 . In this embodiment, the display medium layer  220  is, for example, an electro-phoretic layer, an electro-wetting layer or a cholesteric liquid crystal layer. 
     Referring to  FIG. 4C , the flexible color filter  100  may be formed by the aforementioned steps. Then, the flexible color filter  100  and the controlling elements array substrate  210  are assembled to each other for locating the flexible color filter  100  on the display medium layer  220 . 
     Referring to  FIG. 4D , after assembling the flexible color display medium module  100  on the controlling elements array substrate  210 , a driving circuit  230  is disposed in the peripheral circuit region  210   b  of the controlling elements array substrate  210 . In detail, the driving circuit  230  comprises an IC circuit  232  and a flexible printed circuit  234 . The IC circuit  232  is used for driving the pixel units  214  disposed in the peripheral circuit region  210   b  and the flexible printed circuit  234  is used for electrically connecting the IC circuit  232  to the external circuit (not shown in  FIG. 4C ). In this embodiment, the IC circuit  232  may disposed on the controlling elements array substrate  210  by chip on class process, chip on film process or tape automatic bonding process and electrically connected to the pixel units  214  disposed in the display region  210   a.    
     Specially, the controlling elements array substrate  210  is separated from the rigid substrate  201  after disposing the driving circuit  230  thereon to form the display panel  200  shown in  FIG. 4E . In this embodiment, the substrate  212  may also separated from the rigid substrate  201  by a laser releasing process. 
     Since the flexible substrate is formed on the rigid substrate first, and then the color filter film are formed on the flexible substrate before separating the flexible substrate from the rigid substrate during the fabricating process of the flexible color filter of the invention, the flexible color filter of the invention comparing to the conventional color filter fabricated by roll-to-roll process has improved elements resolution, process yield and capacity. 
     Besides, the display panel of the invention may comprise the aforementioned flexible color display medium module and a flexible controlling elements array substrate. The controlling elements array substrate is formed on a rigid substrate first and separated therefrom after disposing the driving circuit on the flexible controlling elements array substrate. Accordingly, the pixel units of the invention may be formed by the multi-mask process to achieve the best resolution of 1 micrometer, and the flexible substrate may be prevented from deforming as disposing the driving circuit thereon. Therefore, the yield of the driving circuit may avoid decreasing. 
     In summary, the flexible color filter may be produced in mass production scale by the fabricating process of the invention. Moreover, the yield of the flexible color filter and the display panel with the same may be increased and the resolutions of the flexible color filter and the display panel may be improved. 
     The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including configurations ways of the recessed portions and materials and/or designs of the attaching structures. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.