Abstract:
On a flat panel display, a substrate has a first pixel region and a second pixel region defined by a first data line and a second data line extended vertically, and a first gate line and a second gate line extended horizontally. A first pixel electrode and a second pixel electrode are formed in the first pixel region and the second region respectively. The first data line has an opening, and a first broken point and a second broken point are formed between the opening in the second pixel region. A method of repairing the first data line comprises steps of: electrically connecting the first data line and the first pixel electrode within the first pixel region; electrically connecting the first pixel electrode and the second pixel electrode; and electrically connecting the second pixel electrode and the second broken point of the first data line within the second pixel region.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of repairing broken lines and, more particularly, to a method of repairing LCD data lines. 
     2. Description of the Related Art 
     Liquid crystal display(LCD) devices are a well-known form of flat panel displays with advantages of low power consumption, lightweight, thin profile, and low driving voltage. The liquid crystal molecules change their orientations when an electronic field is applied. In the display region of the LCD, an array of pixel regions is patterned by horizontally extended gate lines and vertically extended data lines. Each pixel region has a thin film transistor (TFT) and a pixel electrode. The TFT serves as a switching device. 
     As described above, the TFT array substrate has wiring patterns such as the gate lines and data lines, that supply image signals to drive the pixel electrodes. However, the wiring patterns may easily disconnect if the regions they pass are not smooth or during the heat treatments or etching processes, resulting in open or short circuits. As size and resolution of LCD device continue to increase, large numbers of data lines and gate lines with a narrower line width are required on the TFT array substrate. The fabricating difficulties are also increased, causing a greater possibility of broken wiring patterns. Accordingly, it is desirable to provide a repair method that allows the LCD to operate despite broken wiring. 
     FIG. 1 is a top view showing a conventional method of repairing the disconnected data lines. On a TFT array substrate  10  of an LCD, a display region  20  has a plurality of horizontally extended gate lines  12  and a plurality of vertically extended data lines  16  to form an array of rectangular pixel regions  22 . The TFT array substrate  10  also includes a plurality of gate pads  14  at an end of each gate line  12 , and a plurality of data pads  18  at an end of each data line  16 . In addition, a plurality of repair lines  24 A,  24 B and  24 C are formed to cross the data lines  16  outside the display region  20 . 
     For example, when a broken point A interrupts the image signals passing through the broken data line  16 A, laser fusing or other conventional techniques can be used to connect points  26   a  and  26   b  where the broken data line  16 A meet the repair line  24 A, and the repair line  24 A is cut off at positions  28   a  and  28   b.  Therefore, image signals can go through the repair line  24 A to reach the broken point A. However, a capacitor is existed between the repair line  24 A and the data line  16 A, the image signals will be distorted at the intersecting point  26   a  or  26   b  when passing through the repair line  24 A. Particularly, as the number of data lines  16  increases, the number of the intersecting points also increase, and thus the increased capacitors worsen the signal quality. Moreover, depending on the location of the broken data line, a large delay may be incurred due to the resistance and capacitance of the repair line between opposite ends of the broken data line. This increased delay may be unacceptable for large, high-resolution LCD devices. In addition, a single data line is generally repaired using a single repair line and the number of repair lines  24  is limited due to the size of the display region  20 . Therefore, a method of repairing the broken data lines without fabricating repair lines to solve the aforementioned problems is called for. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method of repairing broken data lines without fabricating extra wiring patterns outside the display region. The repairing method forms a repair line vertically across pixel regions. 
     On a flat display panel, a substrate has a first pixel region and a second pixel region formed by a first data line and a second data line extending vertically, and a first gate line and a second gate line extending horizontally. A first pixel electrode and a second pixel electrode are formed in the first pixel region and the second region respectively. An opening is formed between a first broken point and a second broken point of the first data line in the second pixel region. A method of repairing the first data line comprises steps of: electrically connecting the first data line and the first pixel electrode within the first pixel region; electrically connecting the first pixel electrode and the second pixel electrode; and electrically connecting the second pixel electrode and the second broken point of the first data line within the second pixel region. 
     Accordingly, it is a major object of the invention to use laser fusing to form an electrical connection across the first pixel electrode and the second pixel electrode. 
     It is another object of the invention to repair the line defect on the substrate without fabricating extra wiring patterns on the peripheral region of the pixel region. 
     Yet another object of the invention is to prevent signal distortion caused by the repair line positioned across the adjacent data lines. 
     It is a further object of the invention to provide the electric connection vertically across more than two pixel electrodes if more than one opening is found on the same broken data line. 
     Still another object of the invention is to prevent the increase in RC delay time caused by resistance and capacitance of the repair line. 
     Another object of the invention is to provide an unlimited number of repair lines irrespective of the space and size of the flat display panel. 
     These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top view showing a conventional method of repairing the disconnected data lines. 
     FIG. 2 is a top view showing a method of repairing a data line according to the present invention. 
     FIG. 3 is a top view showing a repair structure according to the present invention. 
     FIGS. 4A to  4 B are sectional views along line IV—IV in FIG. 3 showing the repair process. 
     FIGS. 5A to  5 B are sectional views along line V—V in FIG. 3 showing the repair process. 
     FIG. 6 is a top view showing another repair structure according to the present invention. 
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2 is a top view showing a method of repairing a data line according to the present invention. On a TFT array substrate  30 , a plurality of transverse-extending gate lines  32  and a plurality of lengthwise-extending data lines  34  define an array of rectangular pixel regions  36 . Each pixel region  36  is covered by a pixel electrode  38  and has a TFT device  40 . 
     For example, when an opening  41  is found between the two points A and G on the broken data line  34 A, image signals transferred to the broken data line  34 A cannot pass through the two points A and G. In the method of repairing the broken data line  34 A, laser fusing technique is used on the points B, C, D, E and F respectively to form an electric connection between a first metal layer, a second metal layer and a conductive layer (shown in FIGS.  3  and  4 ). When the points B and C are electrically connected, the broken data line  34 A is electrically connected to the first pixel electrode  381  in the first pixel region  361 . When the points D and E are electrically connected, the first pixel electrode  381  of the first pixel region  361  is electrically connected to the second pixel electrode  382  of the second pixel region  362 . When the points F and G are electrically connected, the second pixel electrode  382  of the second pixel region  362  is electrically connected to the broken data line  34 A. Therefore, the electrically connecting path through the points B□C□D□E□F□G serves a repair line that goes around the opening  41  to repair the line defect between the points A and G on the broken data line  34 A. 
     Compared with the conventional repair method, the method of the present invention uses laser fusing to form an electrical connection vertically across the first pixel electrode  381  and the second pixel electrode  382 , thus the line defect is directly repaired on the substrate  30  without fabricating extra wiring patterns on the peripheral region of the pixel region  36 . Also, since the repair line does not transversely cross the adjacent data lines  34 , signal distortion is prevented. Moreover, if more than one opening is found on the same broken data line  34 A, the repair method can form the electric connection vertically across more than two pixel electrodes  38 . Thus, the number of the repair line is not limited by the space and size of the LCD, and the resistance and capacitance of the repair line will not be increased to cause a RC delay time. 
     FIG. 3 is a top view showing a repair structure according to the present invention. FIGS. 4A to  4 B are sectional views along line IV—IV in FIG. 3 showing the repair process. FIGS. 5A to  5 B are sectional views along line V—V in FIG. 3 showing the repair process. In fabricating the substrate  30 , a first metal layer is deposited and patterned to form the gate line  32 , a gate electrode  401  of the TFT device  40 , a bottom capacitor electrode, and the first electrical connecting layer  42 . Depending on the requirements of electrical performance and repairing locations, the first electrical connecting layer  42  can be formed between the data line  34  and the pixel electrode  38 , or between the pixel electrode  38  and the gate line  32 . 
     Then, an insulating layer  44 , at least a semiconductor layer and a second metal layer  46  are formed on the substrate  30 . Next, the second metal layer  46  is patterned to form a drain electrode  402 , a source electrode  403 , the data lines  34  and an upper capacitor electrode  46 ′. Thereafter, a protection layer  48  and a conductive layer are formed on the substrate  30 , and then the conductive layer is patterned to form the pixel electrode  38 . The first metal layer and the second metal layer  46  are made of metallic materials, and the conductive layer is indium tin oxide (ITO). 
     For example, in the first pixel region  361  and the second pixel region  362 , the first metal layer forms a first gate line  32 A, a second gate line  32 B, a first gate electrode  311 , a second gate electrode  312 , and a bottom capacitor electrode  32 A′ on a predetermined area of the first gate line  32 A. Preferably, a first electrical connecting layer  42  and a third electrical connecting layer  45  are formed near a first gate electrode  311  and a second gate electrode  312  respectively, and a second electrical connecting layer  43  is formed near the bottom capacitor electrode  32 A′. The insulating layer  44  covers the first metal layer. The second metal layer  46  is patterned to form a first data line  34 A, a second data line  34 B, a first drain/source electrode, a second drain/source electrode, and an upper capacitor electrode  46 ′. In the first pixel region  361 , the first data line  34 A has a first protruding portion  462 , the first drain electrode, and a first extending portion  461  of the first drain electrode, all of these parts are positioned above the first electrical connecting layer  42 . In the second pixel region  362 , the first data line  34 A has the second drain electrode, a second drain extending portion  463  of the second drain electrode above the third electrical connecting layer  45 , and a second protruding portion  464  of the first data line above the third electrical connecting layer  45 . The upper capacitor electrode  46 ′ is positioned above the bottom capacitor electrode  32 A′ and extends to cover the second electrical connecting layer  43 . The protection layer  48  is deposited on the second metal layer  46 . The conductive layer is positioned on the protection layer  48  and pattern to form the first pixel electrode  381  and the second pixel electrode  382 . In addition, the first pixel electrode  381  is electrically connected to the first drain electrode via a first contact hole  501 , and the second pixel electrode  381  is electrically connected to the upper capacitor electrode  46 ′ via a second contact hole  502 . 
     In order to ensure the property of the substrate  30 , the line defect can be determined by observing the brightness of each pixel region  36 . Hereinafter, the method of the present invention is provided to repair the data line  34 A having an opening in the second pixel region  362 , for example. First, as shown in FIGS. 4A and 4B, laser fusing is used on a first repair point  51  and a second repair point  52  to remove part of the insulating layer  44 , thus the second metal layer  46  is electrically connected to the first electrical connecting layer  42 . Also, since the second metal layer  46  is connected to the first pixel electrode  381  via the first contact hole  501 , this the electrical connection between the data line  34 A and the first pixel electrode  381  is completed. At this time, the electrical connection between point B and point D is completed. 
     Second, as shown in FIGS. 5A and 5B, laser fusing is used on the third repair point  53  and the fourth repair point  54  to remove part of the protection layer  48  and the insulating layer  44 . Then, the first pixel electrode  381  is electrically connected to the second electrical connecting layer  43 , and the second metal layer  46  is electrically connected to the upper capacitor electrode  46 ′, resulting in a connection between the first pixel electrode  381  and the upper capacitor electrode  46 ′. Also, since the upper capacitor electrode  46 ′ is electrically connected to the second pixel electrode  382  via the second contact hole  502 , the connection between the first pixel electrode  381  and the second pixel electrode  382  is completed. At this time, the connection from the point D to the point E is also completed. 
     Third, as shown in FIGS. 4A and 4B, laser fusing is used on a fifth repair point  55  and a sixth repair point  56  to remove part of the insulating layer  44 , thus the second metal layer  46  is electrically connected to the third electrical connecting layer  45 . Also, since the second metal layer  46  is connected to the second pixel electrode  382  via the third contact hole  503 , the electrical connection between the data line  34 A and the second pixel electrode  382  is finished. At this time, the connection from the point E to the point G shown in FIG. 2 is also completed. 
     According to the above-described method, the present invention uses laser fusing to form electrical connections between the electrical connecting layers  42 ,  43  and  45 , the second metal layer  46 , and the pixel electrodes  381  and  382 . Therefore, the repair line goes around the opening  41  to become an electrical loop. 
     In another preferred embodiment, the location of the electrical connecting layers and the repair points is modified according to the various patterns of the first metal layer  32 , the second metal layer  46  and the conductive layer. FIG. 6 is a top view showing another repair structure according to the present invention. A part of the second pixel electrode  382  covers the bottom capacitor electrode  32 ′ to serve as the upper capacitor electrode  382 ′, and the second metal layer  46  does not cover the bottom capacitor electrode  32 ′. Also, the part of the second pixel electrode  382  further extends to cover part of the second electrical connecting layer  43 . In connecting the point D and the point E shown in FIG. 2, laser fusing is used on the third repair point  53  and the fourth repair point  54  to make an electrical connection between the first pixel electrode  381  and the upper capacitor electrode  382 ′. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.