Abstract:
A flexible printed circuit comprising a substrate, a plurality of function lines, and a plurality of first dummy lines. The substrate comprises at least two periphery areas and an intermediate area. Each periphery area comprises a first layout region, a second layout region and a first rough region disposed between the first and second layout regions. The intermediate area is disposed between the periphery areas. The function lines are disposed on the substrate and within the intermediate area. The first dummy lines are disposed on the substrate and within the first or second layout area.

Description:
This application claims the benefit of Taiwan Application Serial No. 94146099, filed Dec. 23, 2005, the subject matter of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a flexible printed circuit (FPC), and more particularly a FPC applied in a display device. 
   2. Description of the Related Art 
     FIG. 1   a  is a schematic diagram of a conventional FPC applied in a display device. FPCs  131 ˜ 13   n  are coupled between a display panel  11  and a printed circuit board (PCB)  12  for transmitting signals therebetween. Display panel  11  and PCB  12  respectively comprise a plurality of connection lines (not shown) for connecting FPCs  131 ˜ 13   n . FPCs  131 ˜ 13   n  respectively comprise metal lines L 1 ˜L 4 . One terminal of the metal lines L 1 ˜L 4  is coupled to connection lines of display panel  11  and the other terminal of metal lines L 1 ˜L 4  is coupled to connection lines of PCB  12 . 
     FIG. 1   b  shows a cross section along line A-A of  FIG. 1   a . Since the connection methods applied among FPCs  131 ˜ 13   n , display panel  11 , and PCB  12  are the same, a connection method applied among FPC  131 , display panel  11 , and PCB  12  is given as an example. 
   First, Anisotropic Conductive Film (ACF)  14  is disposed among display panel  11 , PCB  12 , and FPC  131 . Next, ACF  14  is heated to increase adhesion capability and pressure is than exerted on display panel  11 , PCB  12 , and FPC  131  to electrically connect connection line L 5  and metal line L 1 , and connection line L 6  and metal line L 1 . 
   Metal line L 1  and connection lines L 5 , L 6  are generally constituted by copper, however, the adhesion capability between copper and ACF  14  is poor. Thus, display panel  11  and PCB  12  are not firmly connected to FPC  13 . 
   To prevent the adhesion problem, the duration that pressure is exerted is increased to increase the adhesion capability between metal line L 1  and connection line L 5 , and metal line L 1  and connection line L 6 . When the pressure duration is increased, the manufacture timing of the display device increases. 
   BRIEF SUMMARY OF THE INVENTION 
   Flexible printed circuits are provided. An exemplary embodiment of a flexible printed circuit comprises a substrate, a plurality of function lines, and a plurality of first dummy lines. The substrate comprises at least two periphery areas and an intermediate area. Each periphery area comprises a first layout region, a second layout region and a first rough region disposed between the first and second layout regions. The intermediate area is disposed between the periphery areas. The function lines are disposed on the substrate and within the intermediate area. The first dummy lines are disposed on the substrate and within the first or second layout area. 
   Display devices are also provided. An exemplary embodiment of a display device comprises a display panel, a printed circuit board, and a flexible printed circuit. The flexible printed circuit electrically connects the display panel and the printed circuit and comprises a substrate, a plurality of function lines, and a plurality of first dummy lines. The substrate comprises at least two periphery areas and an intermediate area. Each periphery area comprises a first layout region, a second layout region and a first rough region disposed between the first and second layout regions. The intermediate area is disposed between the periphery areas. The function lines are disposed on the substrate and within the intermediate area. The first dummy lines are disposed on the substrate and within the first or second layout area. 
   A detailed description is given in the following embodiments with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
       FIG. 1   a  is a schematic diagram of a conventional FPC applied in a display device; 
       FIG. 1   b  shows a cross section along line A-A of  FIG. 1   a;    
       FIG. 2   a  is a schematic diagram of an exemplary embodiment of a FPC; 
       FIG. 2   b  shows a cross section along line B-B of  FIG. 2   a ; and 
       FIGS. 3˜5  are schematic diagrams of another exemplary embodiment of the FPC. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
     FIG. 2   a  is a schematic diagram of an exemplary embodiment of an FPC. A display device  20  comprises a display panel  21 , a PCB  22 , and FPCs  231 ˜ 23   n  electrically connecting display panel  21  and PCB  22  for transmitting control signals from PCB  22  to display panel  21 . Display panel  21  and PCB  22  respectively comprise connection lines (not shown) for connecting FPCs  231 ˜ 23   n . Since the structures of display panel  21  and PCB  22  are well known to those skilled in the art, thus, description thereof is omitted. 
   FPC  231  is given as an example. FPC  231  comprises a substrate  24 , function lines F 1 , F 2 , and dummy lines D 1 ˜D 8 . 
   Substrate  24  comprises periphery areas  241 ,  243  and an intermediate area  242 . Intermediate area  242  is disposed between periphery areas  241  and  243  and comprises function lines F 1  and F 2 . Signals are transmitted between display panel  21  and PCB  22  through function lines F 1  and F 2 . 
   Periphery area  241  comprises layout region  251  and  252 , and a rough region  253 . Rough region  253  is roughed for increasing an adhesion capability between rough region  253  and the ACF, and is disposed between layout regions  251  and  252 . The width of rough region  253  is between 2 cm and 4 cm. In this embodiment, the width of rough region  253  is between 2.3 cm and 4 cm or between 2 cm and 2.3 cm. 
   Layout region  251  comprises dummy lines D 1  and D 2 . Layout region  252  comprises dummy lines D 3  and D 4 . Dummy lines D 1 ˜D 4  cannot transmit signals. In this embodiment, the lengths of dummy lines D 1  and D 2  are equal to that of dummy lines D 3  and D 4 . The number of dummy lines within layout region  251  is equal to that of the dummy lines within layout region  252 , but the disclosure is not limited thereto. 
   Periphery area  243  comprises layout region  261  and  262 , and a rough region  263 . Rough region  263  is roughed and disposed between layout region  261  and  262 . The width of rough region  263  is between 2 cm to 4 cm. In this embodiment, the width of rough region  263  is between 2.3 cm to 4 cm or between 2 cm to 2.3 cm. 
   Layout region  261  comprises dummy lines D 5  and D 6 . Layout region  262  comprises dummy lines D 7  and D 8 . Dummy lines D 5 ˜D 8  cannot transmit signals. In this embodiment, the lengths of dummy lines D 5  and D 6  are equal to that of dummy lines D 7  and D 8 . The number of dummy lines within layout region  261  is equal to that of dummy lines within layout region  262 , but the disclosure is not limited thereto. 
   In some embodiments, dummy lines are disposed within layout regions  251  and  261  or within layout regions  252  and  262 . Additionally, the lengths of dummy lines D 1 ˜D 4  are shorter than that of dummy lines D 5 ˜D 8 . In this embodiment, the lengths of dummy lines D 1 ˜D 4  are equal to that of dummy lines D 5 ˜D 8   
     FIG. 2   b  shows a cross section along line B-B of  FIG. 2   a . ACF  27  is disposed among display panel  21 , PCB  22 , and FPC  231 . When ACF  27  is heated, pressure is exerted on display panel  21 , PCB  22 , and FPC  231  such that dummy line D 1  of FPC  231  is connected to connection line C 1  of display panel  21  and dummy line D 3  of FPC  231  is connected to connection line C 2  of PCB  22 . Since rough region  253  is roughed, an adhesion capability between ACF  27  and FPC  231  is increased for firmly connecting display panel  21 , PCB  22 , and FPC  231 . 
     FIG. 3  is a schematic diagram of another exemplary embodiment of the FPC. FPC  30  comprises a substrate  31  comprising periphery areas  311  and  313 , and an intermediate area  312 . Intermediate area  312  is disposed between periphery areas  311  and  313  and comprises function lines F 31  and F 32 . 
   Since structures of periphery areas  311  and  313  are the same, periphery area  311  is given as an example. Periphery area  311  comprises layout regions  321 ˜ 323  and rough regions  324  and  325 . Rough region  324  is disposed between layout regions  321  and  323  and roughed. Rough region  325  is disposed between layout regions  323  and  322  and roughed. 
   Layout region  321  comprises dummy lines D 31  and D 32 . Layout region  322  comprises dummy lines D 33  and D 34 . Layout region  323  comprises dummy lines D 35  and D 36 . The length, shape, and number of dummy lines D 31 ˜D 34  are not limited. In this embodiment, the lengths of dummy lines D 31 ˜D 34  are the same and shorter than the lengths of dummy lines D 35  and D 36 . 
     FIG. 4  is a schematic diagram of another exemplary embodiment of the FPC.  FIG. 4  is similar to the  FIG. 2  except that a layout region  421  is disposed on the left side of a rough region  424 , a layout region  422  is disposed on the right side of a rough region  424 , and an intermediate area  412  is disposed between periphery areas  411  and  413 . 
     FIG. 5  is a schematic diagram of another exemplary embodiment of the FPC. The  FIG. 5  is similar to the  FIG. 3  except that a layout region  521  is disposed on the left side of a rough region  524 , a layout region  522  is disposed on the right side of a rough region  524 , a layout region  523  is disposed on the left side of a rough region  525 , a layout region  522  is disposed on the right side of a rough region  524 , and an intermediate area  512  is disposed between periphery areas  511  and  513 . 
   As described, because the rough region is roughed, the adhesion capability between ACF and FPC is increased. 
   While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.